diff options
| -rw-r--r-- | .gitattributes | 3 | ||||
| -rw-r--r-- | 37759-0.txt | 11466 | ||||
| -rw-r--r-- | 37759-0.zip | bin | 0 -> 215072 bytes | |||
| -rw-r--r-- | 37759-8.txt | 11467 | ||||
| -rw-r--r-- | 37759-8.zip | bin | 0 -> 214945 bytes | |||
| -rw-r--r-- | 37759-h.zip | bin | 0 -> 528148 bytes | |||
| -rw-r--r-- | 37759-h/37759-h.htm | 13856 | ||||
| -rw-r--r-- | 37759-h/images/illus_002.jpg | bin | 0 -> 74254 bytes | |||
| -rw-r--r-- | 37759-h/images/illus_055.png | bin | 0 -> 39749 bytes | |||
| -rw-r--r-- | 37759-h/images/illus_130.jpg | bin | 0 -> 73518 bytes | |||
| -rw-r--r-- | 37759-h/images/illus_200.jpg | bin | 0 -> 39299 bytes | |||
| -rw-r--r-- | 37759-h/images/illus_204.jpg | bin | 0 -> 45619 bytes | |||
| -rw-r--r-- | 37759-h/images/illus_279.jpg | bin | 0 -> 16441 bytes | |||
| -rw-r--r-- | 37759.txt | 11467 | ||||
| -rw-r--r-- | 37759.zip | bin | 0 -> 214838 bytes | |||
| -rw-r--r-- | LICENSE.txt | 11 | ||||
| -rw-r--r-- | README.md | 2 |
17 files changed, 48272 insertions, 0 deletions
diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/37759-0.txt b/37759-0.txt new file mode 100644 index 0000000..e41be1e --- /dev/null +++ b/37759-0.txt @@ -0,0 +1,11466 @@ +The Project Gutenberg eBook, Darwin, and After Darwin, Volume II (of 3), +by George John Romanes + + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + + + + +Title: Darwin, and After Darwin, Volume II (of 3) + Post-Darwinian Questions: Heredity and Utility + + +Author: George John Romanes + + + +Release Date: October 15, 2011 [eBook #37759] + +Language: English + +Character set encoding: UTF-8 + + +***START OF THE PROJECT GUTENBERG EBOOK DARWIN, AND AFTER DARWIN, VOLUME +II (OF 3)*** + + +E-text prepared by Marilynda Fraser-Cunliffe, L. N. Yaddanapudi, and the +Online Distributed Proofreading Team (http://www.pgdp.net) + + + +Note: Project Gutenberg also has an HTML version of this + file which includes the original illustrations. + See 37759-h.htm or 37759-h.zip: + (http://www.gutenberg.org/files/37759/37759-h/37759-h.htm) + or + (http://www.gutenberg.org/files/37759/37759-h.zip) + + + + + +DARWIN, AND AFTER DARWIN + +II + +Post-Darwinian Questions + +Heredity and Utility + + * * * * * + + +BY THE SAME AUTHOR. + + + DARWIN AND AFTER DARWIN. An Exposition of the Darwinian Theory and a + Discussion of Post-Darwinian Questions. + 1. THE DARWINIAN THEORY. 460 pages. 125 illustrations. Cloth, + $2.00. + 2. POST-DARWINIAN QUESTIONS. Edited by Prof. C. Lloyd Morgan. + 338 pages. Cloth, $1.50. Both volumes together, $3.00 net. + + AN EXAMINATION OF WEISMANNISM. 236 pages. Cloth, $1.00. + + THOUGHTS ON RELIGION. Edited by Charles Gore, M.A., Canon of + Westminster. Second Edition. 184 pages. Cloth, gilt top, $1.25. + + +THE OPEN COURT PUBLISHING COMPANY, +324 DEARBORN STREET, CHICAGO. + + * * * * * + + +[Illustration: Frontispiece] + + +DARWIN, AND AFTER DARWIN + +AN EXPOSITION OF THE DARWINIAN THEORY +AND A DISCUSSION OF POST-DARWINIAN QUESTIONS + +by the Late + +GEORGE JOHN ROMANES, M.A., LL.D., F.R.S. +Honorary Fellow of Gonville and Caius College, Cambridge + +II + +Post-Darwinian Questions +Heredity and Utility + +FOURTH EDITION + + + + + + + +Chicago London +The Open Court Publishing Company +1916 + +Chapter 1 Copyrighted by +The Open Court Publishing Co. +Chicago, Ill., 1895 + +Printed in the +United States of America + + + + +PREFACE + + +As its sub-title announces, the present volume is mainly devoted to a +consideration of those Post-Darwinian Theories which involve fundamental +questions of Heredity and Utility. + +As regards Heredity, I have restricted the discussion almost exclusively +to Professor Weismann's views, partly because he is at present by far +the most important writer upon this subject, and partly because his +views with regard to it raise with most distinctness the issue which +lies at the base of all Post-Darwinian speculation touching this +subject--the issue as to the inheritance or non-inheritance of acquired +characters. + +My examination of the Utility question may well seem to the general +reader needlessly elaborate; for to such a reader it can scarcely fail +to appear that the doctrine which I am assailing has been broken to +fragments long before the criticism has drawn to a close. But from my +previous experience of the hardness with which this fallacious doctrine +dies, I do not deem it safe to allow even one fragment of it to remain, +lest, hydra-like, it should re-develop into its former proportions. And +I can scarcely think that naturalists who know the growing prevalence of +the doctrine, and who may have followed the issues of previous +discussions with regard to it, will accuse me of being more over-zealous +in my attempt to make a full end thereof. + +One more remark. It is a misfortune attending the aim and scope of Part +II that they bring me into frequent discord with one or other of the +most eminent of Post-Darwinian writers--especially with Mr. Wallace. But +such is the case only because the subject-matter of this volume is +avowedly restricted to debateable topics, and because I choose those +naturalists who are deservedly held in most esteem to act spokesmen on +behalf of such Post-Darwinian views as appear to me doubtful or +erroneous. Obviously, however, differences of opinion on particular +points ought not to be taken as implying any failure on my part to +recognize the general scientific authority of these men, or any +inability to appreciate their labours in the varied fields of Biology. + +G. J. R. +CHRIST CHURCH, OXFORD. + + + + +NOTE + +Some time before his death Mr. Romanes decided to publish those sections +of his work which deal with Heredity and Utility, as a separate volume, +leaving Isolation and Physiological Selection for the third and +concluding part of _Darwin, and after Darwin_. + +Most of the matter contained in this part was already in type, but was +not finally corrected for the press. The alterations made therein are +for the most part verbal. + +Chapter IV was type-written; in it, too, no alterations of any moment +have been made. + +For Chapters V and VI there were notes and isolated paragraphs not yet +arranged. I had promised during his life to write for Mr. Romanes +Chapter V on the basis of these notes, extending it in such ways as +seemed to be desirable. In that case it would have been revised and +amended by the author and received his final sanction. Death annulled +this friendly compact; and since, had I written the chapter myself, it +could not receive that imprimatur which would have given its chief +value, I have decided to arrange the material that passed into my hands +without adding anything of importance thereto. The substance of Chapters +V and VI is therefore entirely the author's: even the phraseology is +his; the arrangement only is by another hand. + +Such parts of the Preface as more particularly refer to Isolation and +Physiological Selection are reserved for publication in Part III. A year +or more must elapse before that part will be ready for publication. + +Mr. F. Howard Collins has, as a kindly tribute to the memory of the +author, read through the proofs. Messrs. F. Darwin, F. Galton, H. +Seebohm, and others, have rendered incidental assistance. After much +search I am unable to give the references to one or two passages. + +I have allowed a too flattering reference to myself to stand, in +accordance with a particular injunction of Mr. Romanes given shortly +before that sad day on which he died, leaving many to mourn the loss of +a personal friend most bright, lovable, and generous-hearted, and +thousands to regret that the hand which had written so much for them +would write for them no more. + +C. LL. M. + +UNIVERSITY COLLEGE, BRISTOL, +_April, 1894_. + + + + +CONTENTS + + PAGE +CHAPTER I. +INTRODUCTORY: THE DARWINISM OF DARWIN AND OF THE +POST-DARWINIAN SCHOOLS 1 + +CHAPTER II. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Preliminary_) 39 + +CHAPTER III. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + A. _Indirect evidence in favour of the Inheritance of Acquired + Characters_ 60 + B. _Inherited effects of Use and of Disuse_ 95 + +CHAPTER IV. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + C. _Experimental evidence in favour of the Inheritance of Acquired + Characters_ 103 + +CHAPTER V. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + A. and B. _Direct and Indirect Evidence in favour of the + Non-inheritance of Acquired Characters_ 133 + + C. _Experimental Evidence as to the Non-inheritance of Acquired + Characters_ 142 + +CHAPTER VI. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Conclusion_) 150 + +CHAPTER VII. +CHARACTERS AS ADAPTIVE AND SPECIFIC 159 + +CHAPTER VIII. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Continued_) + I. _Climate_ 200 + II. _Food_ 217 + III. _Sexual Selection_ 219 + IV. _Isolation_ 223 + V. _Laws of Growth_ 226 + +CHAPTER IX. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Continued_) 228 + +CHAPTER X. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Concluded_) 251 + SUMMARY 274 + +APPENDIX I. ON PANMIXIA 291 + +APPENDIX II. ON CHARACTERS AS ADAPTIVE AND SPECIFIC 307 + +NOTE A TO PAGE 57 333 + +NOTE B TO PAGE 89 337 + + + + +LIST OF ILLUSTRATIONS + + PAGE + +Portrait of George John Romanes _Frontispiece_ + +Diagram of Prof. Weismann's Theories 43 + +FIG. 1. Guinea pigs, showing gangrene of ears due to injury of + restiform bodies 118 + +FIG. 2. Old Irish Pig (after Richardson) 188 + +FIG. 3. Skulls of Niata Ox and of Wild White Ox 192 + +FIG. 4. Lower teeth of Orang (after Tomes) 261 + + + + +CHAPTER I. + +INTRODUCTORY: THE DARWINISM OF DARWIN, AND OF THE POST-DARWINIAN +SCHOOLS. + + +It is desirable to open this volume of the treatise on _Darwin and after +Darwin_ by taking a brief survey of the general theory of descent, +first, as this was held by Darwin himself, and next, as it is now held +by the several divergent schools of thought which have arisen since +Darwin's death. + +The most important of the questions in debate is one which I have +already had occasion to mention, while dealing, in historical order, +with the objections that were brought against the theory of natural +selection during the life-time of Darwin[1]. Here, however, we must +consider it somewhat more in detail, and justify by quotation what was +previously said regarding the very definite nature of his utterances +upon the matter. This question is whether natural selection has been the +sole, or but the main, cause of organic evolution. + + [1] Part I, pp. 253-256. + +Must we regard survival of the fittest as the one and only principle +which has been concerned in the progressive modification of living +forms, or are we to suppose that this great and leading principle has +been assisted by other and subordinate principles, without the +co-operation of which the results, as presented in the animal and +vegetable kingdoms, could not have been effected? Now Darwin's answer to +this question was distinct and unequivocal. He stoutly resisted the +doctrine that natural selection was to be regarded as the only cause of +organic evolution. On the other hand, this opinion was--and still +continues to be--persistently maintained by Mr. Wallace; and it +constitutes the source of all the differences between his views and +those of Darwin. Moreover, up to the time of Darwin's death, Mr. Wallace +was absolutely alone in maintaining this opinion: the whole body of +scientific thought throughout the world being against him; for it was +deemed improbable that, in the enormously complex and endlessly varied +processes of organic evolution, only a single principle should be +everywhere and exclusively concerned[2]. But since Darwin's death there +has been a great revolution of biological thought in favour of Mr. +Wallace's opinion. And the reason for this revolution has been, that his +doctrine of natural selection as the sole cause of organic evolution has +received the corroborative support of Professor Weismann's theory of +heredity--which has been more or less cordially embraced by a certain +section of evolutionists, and which appears to carry the doctrine in +question as a logical corollary, so far, at all events, as adaptive +structures are concerned. + + [2] _Contributions to the Theory of Natural Selection_, p. 47. + +Now in this opening chapter we shall have to do merely with a setting +forth of Darwin's opinion: we are not considering how far that opinion +ought to be regarded as having been in any measure displaced by the +results of more recent progress. Such, then, being the only matter which +here concerns us, I will supply a few brief quotations, to show how +unequivocally Darwin has stated his views. First, we may take what he +says upon the "Lamarckian factors[3];" and next we may consider what he +says with regard to other factors, or, in general, upon natural +selection not being the sole cause of organic evolution. + + [3] So far as we shall be concerned with them throughout this + treatise, the "Lamarckian factors" consist in the supposed + transmission of acquired characters, whether the latter be due + to the direct influence of external conditions of life on the + one hand, or to the inherited effects of use and disuse on the + other. For the phrase "inherited effects of use and disuse," I + shall frequently employ the term "use-inheritance," which has + been coined by Mr. Platt Ball as a more convenient expression. + + "Changed habits produce an inherited effect, as in the period of + the flowering of plants when transported from one climate to + another. With animals the increased use or disuse of parts has had + a more marked influence[4]." + + [4] _Origin of Species_, 6th ed. p. 8. + + "There can be no doubt, from the facts given in this chapter, that + extremely slight changes in the conditions of life sometimes, + probably often, act in a definite manner on our domesticated + productions; and, as the action of changed conditions in causing + indefinite variability is accumulative, so it may be with their + definite action. Hence considerable and definite modifications of + structure probably follow from altered conditions acting during + long series of generations[5]." + + [5] _Variation_ &c. 2nd ed. ii. p. 280. + + "How, again, can we explain the inherited effects of the use and + disuse of particular organs? The domesticated duck flies less and + walks more than the wild duck, and its limb bones have become + diminished and increased in a corresponding manner in comparison + with those of the wild duck. A horse is trained to certain paces, + and the colt inherits similar consensual movements. The + domesticated rabbit becomes tame from close confinement; the dog, + intelligent from associating with man; the retriever is taught to + fetch and carry; and these mental endowments and bodily powers are + all inherited. Nothing in the whole circuit of physiology is more + wonderful. How can the use or disuse of a particular limb or of the + brain affect a small aggregate of reproductive cells, seated in a + distant part of the body, in such a manner that the being developed + from these cells inherits the characters of either one or both + parents?... In the chapters devoted to inheritance, it was shown + that a multitude of newly acquired characters, whether injurious or + beneficial, whether of the lowest or highest vital importance, are + often faithfully transmitted[6]." + + [6] _Variation_ &c. ii. p. 367. + + "When discussing special cases, Mr. Mivart passes over the effects + of the increased use and disuse of parts, which I have always + maintained to be highly important, and have treated in my + 'Variation under Domestication' at greater length than, as I + believe, any other writer[7]." + + [7] _Origin of Species_, p. 176. + +So much for the matured opinion of Darwin touching the validity of the +theory of use-inheritance. Turning now to his opinion on the question +whether or not there are yet any further factors concerned in the +process of organic evolution, I think it will be sufficient to quote a +single passage from the _Origin of Species_. The first paragraph of the +"Conclusion" is devoted to a _résumé_ of his views upon this matter, and +consists of the following most emphatic words. + + "I have now recapitulated the facts and considerations which have + thoroughly convinced me that species have been modified, during a + long course of descent. This has been effected chiefly through the + natural selection of numerous successive, slight, favourable + variations; aided in an important manner by the inherited effects + of the use and disuse of parts; and in an unimportant manner, that + is in relation to adaptive structures, whether past or present, by + the direct action of external conditions, and by variations which + seem to us in our ignorance to arise spontaneously. It appears that + I formerly underrated the frequency and value of these latter forms + of variation, as leading to permanent modifications of structure + independently of natural selection. But as my conclusions have + lately been much misrepresented, and it has been stated that I + attribute the modification of species exclusively to natural + selection, I may be permitted to remark that in the first edition + of this work, and subsequently, I placed in a most conspicuous + position--namely, at the close of the Introduction--the following + words: 'I am convinced that natural selection has been the main, + but not the exclusive means of modification.' This has been of no + avail. Great is the power of steady misrepresentation; but the + history of science shows that fortunately this power does not long + endure." + +In the whole range of Darwin's writings there cannot be found a passage +so strongly worded as this: it presents the only note of bitterness in +all the thousands of pages which he has published. Therefore I do not +think it is necessary to supply any further quotations for the purpose +of proving the state of his opinion upon the point in question. But, be +it carefully noted, from this great or radical difference of opinion +between the joint originators of the theory of natural selection, all +their other differences of opinion arise; and seeing that since the +death of Darwin a large number of naturalists have gone over to the side +of Wallace, it seems desirable here to state categorically what these +other or sequent points of difference are. Without at present discussing +them, therefore, I will merely set them out in a tabular form, in order +that a clear perception may be gained of their logical connexion with +this primary point of difference. + + |_The Theory of Natural |_The theory of Natural | + |Selection according to |Selection according to | + |Darwin._ |Wallace._ | + | | | + |Natural Selection has been |Natural Selection has been | + |the main means of |the sole means of | + |modification, not excepting |modification, excepting in | + |the case of Man. |the case of Man. | + | | | + |(_a_) Therefore it is a |(_a_) Therefore it is | + |question of evidence |antecedently impossible | + |whether the Lamarckian |that the Lamarckian factors | + |factors have co-operated. |can have co-operated. | + | | | + |(_b_) Neither all species, |(_b_) Not only all species, | + |nor, _a fortiori_, all |but all specific | + |specific characters, have |characters, must | + |been due to natural |necessarily have been due | + |selection. |to natural selection. | + | | | + |(_c_) Thus the principle of |(_c_) Thus the principle of | + |Utility is not of universal |Utility must necessarily be | + |application, even where |of universal application, | + |species are concerned. |where species are | + | |concerned. | + | | | + |(_d_) Thus, also, the |(_d_) Thus, also, the | + |suggestion as to Sexual |suggestion as to Sexual | + |Selection, or any other |Selection, or of any other | + |supplementary cause of |supplementary cause of | + |modification, may be |modification, must be ruled | + |entertained; and, as in the |out; and, as in the case of | + |case of the Lamarckian |the Lamarckian factors, | + |factors, it is a question |their co-operation deemed | + |of evidence whether, or how |impossible. | + |far, they have co-operated. | | + | | | + |(_e_) No detriment arises |(_e_) The possibility--and, | + |to the theory of natural |_a fortiori_ the | + |selection as a theory of |probability--of any | + |the origin of species by |supplementary factors | + |entertaining the |cannot be entertained | + |possibility, or the |without serious detriment | + |probability, of |to the theory of natural | + |supplementary factors. |selection, as a theory of | + | |the origin of species. | + | | | + |(_f_) Cross-sterility in |(_f_) Cross-sterility in | + |species cannot possibly be |species is probably due to | + |due to natural selection. |natural selection[8]. | + + [8] This, to the best of my judgement, is the fairest extract that I + can give of Mr. Wallace's most recently published opinions on + the points in question. [In particular as regards (_a_) see + _Darwinism_ pp. 435-6.] But with regard to some of them, his + expression of opinion is not always consistent, as we shall find + in detail later on. Besides, I am here taking Mr. Wallace as + representative of the Neo-Darwinian school, one or other + prominent member of which has given emphatic expression to each + of the above propositions. + +As it will be my endeavour in the ensuing chapters to consider the +rights and the wrongs of these antithetical propositions, I may reserve +further quotations from Darwin's works, which will show that the above +is a correct epitome of his views as contrasted with those of Wallace +and the Neo-Darwinian school of Weismann. But here, where the object is +merely a statement of Darwin's theory touching the points in which it +differs from those of Wallace and Weismann, it will be sufficient to set +forth these points of difference in another and somewhat fuller form. So +far then as we are at present concerned, the following are the matters +of doctrine which have been clearly, emphatically, repeatedly, and +uniformly expressed throughout the whole range of Darwin's writings. + +1. That natural selection has been the main means of modification. + +2. That, nevertheless, it has not been the only means; but has been +supplemented or assisted by the co-operation of other causes. + +3. That the most "important" of these other causes has been the +inheritance of functionally-produced modifications (use-inheritance); +but this only because the transmission of such modifications to progeny +must always have had immediate reference to _adaptive_ ends, as +distinguished from merely useless change. + +4. That there are sundry other causes which lead to merely useless +change--in particular, "the direct action of external conditions, and +variations which seem to us in our ignorance to arise spontaneously." + +5. Hence, that the "principle of utility," far from being of universal +occurrence in the sphere of animate nature, is only of what may be +termed highly general occurrence; and, therefore, that certain other +advocates of the theory of natural selection were mistaken in +representing the universality of this principle as following by way of +necessary consequence from that theory. + +6. Cross-sterility in species cannot possibly be due to natural +selection; but everywhere arises as a result of some physiological +change having exclusive reference to the sexual system--a change which +is probably everywhere due to the same cause, although what this cause +could be Darwin was confessedly unable to suggest. + +Such, then, was the theory of evolution as held by Darwin, so far as the +points at present before us are concerned. And, it may now be added, +that the longer he lived, and the more he pondered these points, the +less exclusive was the _rôle_ which he assigned to natural selection, +and the more importance did he attribute to the supplementary factors +above named. This admits of being easily demonstrated by comparing +successive editions of his works; a method adopted by Mr. Herbert +Spencer in his essay on the _Factors of Organic Evolution_. + +My object in thus clearly defining Darwin's attitude regarding these +sundry points is twofold. + +In the first place, with regard to merely historical accuracy, it +appears to me undesirable that naturalists should endeavour to hide +certain parts of Darwin's teaching, and give undue prominence to others. +In the second place, it appears to me still more undesirable that this +should be done--as it usually is done--for the purpose of making it +appear that Darwin's teaching did not really differ very much from that +of Wallace and Weismann on the important points in question. I myself +believe that Darwin's judgement with regard to all these points will +eventually prove more sound and accurate than that of any of the recent +would-be improvers upon his system; but even apart from this opinion of +my own it is undesirable that Darwin's views should be misrepresented, +whether the misrepresentation be due to any unfavourable bias against +one side of his teaching, or to sheer carelessness in the reading of his +books. Yet the new school of evolutionists, to which allusion has now so +frequently been made, speak of their own modifications of Darwin's +teaching as "pure Darwinism," in contradistinction to what they call +"Lamarckism." In other words, they represent the principles of +"Darwinism" as standing in some kind of opposition to those of +"Lamarckism": the Darwinian principle of natural selection, they think, +is in itself enough to account for all the facts of adaptation in +organic nature. Therefore they are eager to dispense with the Lamarckian +principle of the inherited effects of use and disuse, together with the +direct influence of external conditions of life, and all or any other +causes of modification which either have been, or in the future may +possibly be, suggested. Now, of course, there is no reason why any one +should not hold these or any other opinions to which his own +independent study of natural science may lead him; but it appears to me +that there is the very strongest reason why any one who deviates from +the carefully formed opinions of such a man as Darwin, should above all +things be careful to be absolutely fair in his representations of them; +he should be scrupulously jealous, so to speak, of not letting it appear +that he is unjustifiably throwing over his own opinions the authority of +Darwin's name. + +But in the present case, as we have seen, not only do the Neo-Darwinians +strain the teachings of Darwin; they positively reverse those +teachings--representing as anti-Darwinian the whole of one side of +Darwin's system, and calling those who continue to accept that system in +its entirety by the name "Lamarckians." I know it is sometimes said by +members of this school, that in his utilization of Lamarckian principles +as accessory to his own, Darwin was actuated by motives of "generosity." +But a more preposterous suggestion could not well be made. We may +fearlessly challenge any one who speaks or writes in such a way, to show +any other instance where Darwin's great generosity of disposition had +the effect of influencing by one hair's breadth his still greater +loyalty to truth. Moreover, and with special regard to this particular +case, I would point out that in no one of his many allusions to, and +often lengthy discussions of, these so-called Lamarckian principles, +does he ever once introduce the name of Lamarck; while, on the other +hand, in the only places where he does so--whether in his books or in +his now published letters--he does so in order to express an almost +contemptuous dissatisfaction, and a total absence of obligation. Hence, +having regard to the "generosity" with which he always acknowledged +obligations, there can be no reasonable doubt that Darwin was not in the +smallest degree influenced by the speculative writings of Lamarck; or +that, even if Lamarck had never lived, the _Origin of Species_ would +have differed in any single particular from the form in which it now +stands. Finally, it must not be forgotten that Darwin's acceptance of +the theory of use-inheritance was vitally essential to his theory of +Pangenesis--that "beloved child" over which he had "thought so much as +to have lost all power of judging it[9]." + + [9] _Life and Letters_, vol. iii. pp. 72 and 75. + +What has just been said touching the relations between Darwin's theory +and that of Lamarck, applies with equal force to the relations between +Darwin's theory and any other theory appertaining to evolution which has +already been, or may hereafter be propounded. Yet so greatly have some +of the Neo-Darwinians misunderstood the teachings of Darwin, that they +represent as "Darwinian heresy" any suggestions in the way of factors +"supplementary to," or "co-operative with" natural selection. Of course, +if these naturalists were to avow themselves followers of Wallace, +instead of followers of Darwin, they would be perfectly justified in +repudiating any such suggestions as, _ipso facto_ heretical. But, as we +have now seen, through all his life Darwin differed from Wallace with +regard to this very point; and therefore, unlike Wallace, he was always +ready to entertain "additional suggestions" regarding the causes of +organic evolution--several of which, indeed, he himself supplied. Hence +we arrive at this curious state of matters. Those biologists who of late +years have been led by Weismann to adopt the opinions of Wallace, +represent as anti-Darwinian the opinions of other biologists who still +adhere to the unadulterated doctrines of Darwin. Weismann's _Essays on +Heredity_ (which argue that natural selection is the only possible cause +of adaptive modification) and Wallace's work on _Darwinism_ (which in +all the respects where any charge of "heresy" is concerned directly +contradicts the doctrine of Darwin)--these are the writings which are +now habitually represented by the Neo-Darwinians as setting forth the +views of Darwin in their "pure" form. The result is that, both in +conversation and in the press, we habitually meet with complete +inversions of the truth, which show the state of confusion into which a +very simple matter has been wrought by the eagerness of certain +naturalists to identify the views of Darwin with those of Wallace and +Weismann. But we may easily escape this confusion, if we remember that +wherever in the writings of these naturalists there occur such phrases +as "pure Darwinism" we are to understand pure _Wallaceism_, or the pure +theory of natural selection to the exclusion of any supplementary +theory. Therefore it is that for the sake of clearness I coined, several +years ago, the terms "Neo-Darwinian" and "Ultra-Darwinian" whereby to +designate the school in question. + + * * * * * + +So much, then, for the Darwinism of Darwin, as contrasted with the +Darwinism of Wallace, or, what is the same thing, of the Neo-Darwinian +school of Weismann. Next we may turn, by way of antithesis, to the +so-called "Neo-Lamarckian" school of the United States. For, by a +curious irony of fate, while the Neo-Darwinian school is in Europe +seeking to out-Darwin Darwin by assigning an exclusive prerogative to +natural selection in both kingdoms of animate nature, the Neo-Lamarckian +school is in America endeavouring to reform Darwinism in precisely the +opposite direction--viz. by transferring the sovereignty from natural +selection to the principles of Lamarck. Without denying to natural +selection a more or less important part in the process of organic +evolution, members of this school believe that much greater importance +ought to be assigned to the inherited effects of use and disuse than was +assigned to these agencies by Darwin. Perhaps this noteworthy state of +affairs, within a decade of Darwin's death, may lead us to anticipate +that his judgement--standing, as it does, between these two +extremes--will eventually prove the most accurate of all, with respect +to the relative importance of these factors of evolution. But, be this +as it may, I must now offer a few remarks upon the present position of +the matter. + +In the first place, to any one who (with Darwin and against Weismann) +admits not only the abstract possibility, but an actual working, of the +Lamarckian factors, it becomes difficult to determine, even +approximately, the degrees of value which ought to be ascribed to them +and to natural selection respectively. For, since the results are in +both cases identical in kind (as, adaptive changes of organic types), +where both sets of causes are supposed to be in operation together, we +have no means of estimating the relative shares which they have had in +bringing about these results. Of course there are large numbers of cases +where it cannot possibly be supposed that the Lamarckian factors have +taken any part at all in producing the observed effects; and therefore +in such cases there is almost full agreement among evolutionists in +theoretically ascribing such effects to the exclusive agency of natural +selection. Of such, for instance, are the facts of protective colouring, +of mimicry, of the growth of parts which, although _useful_, are never +_active_ (e.g. shells of mollusks, hard coverings of seeds), and so on. +But in the majority of cases where adaptive structures are concerned, +there is no means of discriminating between the influences of the +Lamarckian and the Darwinian factors. Consequently, if by the +Neo-Lamarckian school we understand all those naturalists who assign any +higher importance to the Lamarckian factors than was assigned to them by +Darwin, we may observe that members of this school differ very greatly +among themselves as to the degree of importance that ought to be +assigned. On the one hand we have, in Europe, Giard, Perrier, and Eimer, +who stand nearer to Darwin than do a number of the American +representatives--of whom the most prominent are Cope, Osborn, Packard, +Hyatt, Brooks, Ryder, and Dall. The most extreme of these is Professor +Cope, whose collection of essays entitled _The Origin of the Fittest_, +as well as his more recent and elaborate monograph on _The Development +of the Hard Parts of the Mammalia_, represent what appears even to some +other members of his school an extravagant estimate of the importance +of Lamarckian principles. + +But the most novel, and in many respects the most remarkable school of +what may be termed Anti-selectionists is one which is now (1894) rapidly +increasing both in numbers and in weight, not only in the New World, but +also in Germany, and to a lesser extent, in Great Britain. + +This school, without being either Lamarckian or Darwinian (for its +individual members differ widely from one another in these respects) +maintains a principle which it deems of more importance than either +use-inheritance or natural selection. This principle it calls +Self-adaptation. It is chiefly botanists who constitute this school, and +its principal representatives, in regard to authority, are Sachs, +Pfeffer and Henslow. + +Apart from topics which are to be dealt with in subsequent chapters, the +only matters of much importance which have been raised in the +Post-Darwinian period are those presented by the theories of Geddes, +Cope, Hyatt, and others, and certain more or less novel ideas set forth +in Wallace's _Darwinism_. + +Mr. Geddes has propounded a new theory of the origin of species, which +in his judgement supersedes to a large extent the theory of natural +selection. He has also, in conjunction with Mr. Thomson, propounded a +theory of the origin of sex. For my own part, I cannot see that these +views embody any principles or suggestions of a sufficiently definite +kind to constitute them theories at all. In this respect the views of +Mr. Geddes resemble those of Professors Cope, Hyatt, and others, on what +they term "the law of acceleration and retardation." In all these +cases, so far as I can see, the so-called explanations are not in fact +any explanations; but either a mere re-statement of the facts, or else +an enunciation of more or less meaningless propositions. Thus, when it +is said that the evolution of any given type has been due to the +"acceleration of growth-force" with respect to some structures, and the +"retardation of growth-force" with respect to others, it appears evident +that we have not any real explanation in terms of causality; we have +only the form of an explanation in the terms of a proposition. All that +has been done is to express the fact of evolution in somewhat obscure +phraseology, since the very thing we want to know about this fact +is--What are the causes of it as a fact, or the reasons which have led +to the increase of some of the parts of any given type, and the +concomitant decrease of others? It is merely the facts themselves that +are again presented by saying that the development has been in the one +case accelerated, while in the other it has been retarded[10]. + + [10] Take, for example, the following, which is a fair epitome of + the whole:--"I believe that this is the simplest mode of + stating and explaining the law of variation; that some forms + acquire something which their parents did not possess; and that + those which acquire something additional have to pass through + more numerous stages than their ancestors; and those which lose + something pass through fewer stages than their ancestors; and + these processes are expressed by the terms 'acceleration' and + 'retardation'" (_Origin of the Fittest_, pp. 125, 226, and + 297). Even if this be "the simplest mode of _stating_ the law + of variation," it obviously does nothing in the way of + _explaining_ the law. + +So much for what may be termed this New World theory of the origin of +species: it is a mere re-statement of the facts. Mr. Geddes' theory, on +the other hand, although more than a mere re-statement of the facts, +appears to me too vague to be of any explanatory service. His view is +that organic evolution has everywhere depended upon an antagonism, +within the limits of the same organism, between the processes of +nutrition and those of reproduction. But although he is thus able +hypothetically to explain certain facts--such as the shortening of a +flower-spike into a composite flower--the suggestion is obviously +inadequate to meet, even hypothetically, most of the facts of organic +evolution, and especially the development of _adaptive_ structures. +Therefore, it seems to me, we may dismiss it even as regards the +comparatively few facts which it might conceivably explain--seeing that +these same facts may be equally well explained by the causes which are +already known to operate in other cases. For it is the business of +natural selection to ensure that there shall nowhere be any needless +expenditure of vital energy, and, consequently, that everywhere the +balance between nutrition and reproduction shall be most profitably +adjusted. + +Similarly with respect to the theory of the _Origin of Sex_, I am unable +to perceive even this much of scientific relevancy. As stated by its +authors the theory is, that the female is everywhere "anabolic," as +compared with the male, which is "katabolic." By anabolic is meant +comparative inactivity of protoplasmic change due to a nutritive winding +up of molecular constitution, while by katabolic is meant the opposite +condition of comparative activity due to a dynamic running down of +molecular constitution. How, then, can the _origin_ of sex be explained, +or the _causes_ which led to the differentiation of the sexes be shown +by saying that the one sex is anabolic and the other katabolic? In so +far as these verbal statements serve to express what is said to be a +general fact--namely, that the female sexual elements are less mobile +than the male--they merely serve to re-state this general fact in +terminology which, as the authors themselves observe, is "unquestionably +ugly." But in so far as any question of _origin_ or _causality_ is +concerned, it appears to me that there is absolutely no meaning in such +statements. They belong to the order of merely formal explanations, as +when it is said that the toxic qualities of morphia are due to this drug +possessing a soporific character. + +Much the same, in my opinion, has to be said of the Rev. G. Henslow's +theory of the origin of species by what he terms "self-adaptation." +Stated briefly his view is that there is no sufficient evidence of +natural selection as a _vera causa_, while there is very abundant +evidence of adjustments occurring without it, first in individual +organisms, and next, by inheritance of acquired characters, in species. +Now, much that he says in criticism of the selection theory is of +considerable interest as such; but when we pass from the critical to the +constructive portions of his books and papers, we again meet with the +want of clearness in thought between a statement of facts in terms of a +proposition, and an explanation of them in those of causality. Indeed, I +understand from private correspondence, that Mr. Henslow himself admits +the validity of this criticism; for in answer to my questions,--"How +does Self-adaptation work in each case, and why should protoplasm be +able to _adapt itself_ into the millions of diverse mechanisms in +nature?"--he writes. "Self-adaptation does not profess to be a _vera +causa_ at all; for the true causes of variation can only be found in the +answer to your [above] questions, and I must say at once, _these +questions cannot be answered_." That is, they cannot be answered on the +hypothesis of self-adaptation, which is therefore a statement of the +facts of adaptation as distinguished from an explanation of them. +Nevertheless, two things have here to be noted. In the first place, the +statement of facts which Mr. Henslow has collected is of considerable +theoretical importance as tending to show that there are probably causes +of an internal kind (i. e. other than natural selection) which have been +largely concerned in the adaptive modification of plants. And, in the +second place, it is not quite true that the theory of self-adaptation +is, as its author says in the sentences above quoted, a mere statement +of the facts of adaptation, without any attempt at explaining their +causes. For in his published words he does attempt to do so[11]. And, +although I think his attempt is a conspicuous failure, I ought in +fairness to give examples of it. His books are almost exclusively +concerned in an application of his theory to the mechanisms of flowers +for securing their own fertilization. These mechanisms he ascribes, in +the case of entomophylous flowers, to the "thrusts," "strains," and +other "irritations" supplied to the flowers by their insect visitors, +and consequent "reactions" of the vegetable "protoplasm." But no attempt +is made to show why these "reactions" should be of an _adaptive_ kind, +so as to build up the millions of diverse and often elaborate mechanisms +in question--including not only forms and movements, but also colours, +odours, and secretions. For my own part I confess that, even granting to +an ultra-Lamarckian extent the inheritance of acquired characters, I +could conceive of "self-adaptation" alone producing all such innumerable +and diversified adjustments only after seeing, with Cardinal Newman, an +angel in every flower. Yet Mr. Henslow somewhat vehemently repudiates +any association between his theory and that of teleology. + + [11] _Floral Structures_ (Internat. Sc. Ser. lxiv. 1888): _The + Making of Flowers_ (Romance of Science Ser. 1891); and Linn. + Soc. Papers 1893-4. + +On the whole, then, I regard all the works which are here classed +together (those by Cope, Geddes, and Henslow), as resembling one another +both in their merits and defects. Their common merits lie in their +erudition and much of their criticism, while their common defects +consist on the one hand in not sufficiently distinguishing between mere +statements and real explanations of facts, and, on the other, in not +perceiving that the theories severally suggested as substitutes for that +of natural selection, even if they be granted true, could be accepted +only as co-operative factors, and by no stretch of logic as substitutes. + + * * * * * + +Turning now to Mr. Wallace's work on _Darwinism_, we have to notice, in +the first place, that its doctrine differs from "Darwinism" in regard to +the important dogma which it is the leading purpose of that work to +sustain--namely, that "the law of utility" is, to all intents and +purposes, universal, with the result that natural selection is virtually +the only cause of organic evolution. I say "to all intents and +purposes," or "virtually," because Mr. Wallace does not expressly +maintain the abstract impossibility of laws and causes other than those +of utility and natural selection; indeed, at the end of his treatise, he +quotes with approval Darwin's judgement, that "natural selection has +been the most important, but not the exclusive means of modification." +Nevertheless, as he nowhere recognizes any other law or cause of +adaptive evolution[12], he practically concludes that, on inductive or +empirical grounds, there _is_ no such other law or cause to be +entertained--until we come to the particular case of the human mind. But +even in making this one particular exception--or in representing that +some other law than that of utility, and some other cause than that of +natural selection, must have been concerned in evolving the mind of +man--he is not approximating his system to that of Darwin. On the +contrary, he is but increasing the divergence, for, of course, it was +Darwin's view that no such exception could be legitimately drawn with +respect to this particular instance. And if, as I understand must be the +case, his expressed agreement with Darwin touching natural selection not +being the only cause of adaptive evolution has reference to this point, +the quotation is singularly inapt. + + [12] "The law of correlation," and the "laws of growth," he does + recognize; and shows that they furnish an explanation of the + origin of many characters, which cannot be brought under "the + law of utility." + +Looking, then, to these serious differences between his own doctrine of +evolution--both organic and mental--and that of Darwin, I cannot think +that Mr. Wallace has chosen a suitable title for his book; because, in +view of the points just mentioned, it is unquestionable that _Darwinism_ +differs more widely from the _Origin of Species_ than does the _Origin +of Species_ from the writings of the Neo-Lamarckians. But, passing over +this merely nominal matter, a few words ought to be added on the very +material question regarding the human mind. In subsequent chapters the +more general question, or that which relates to the range of utility and +natural selection elsewhere will be fully considered. + +Mr. Wallace says,-- + + "The immense interest that attaches to the origin of the human + race, and the amount of misconception which prevails regarding the + essential teachings of Darwin's theory on the question, as well as + regarding my own special views upon it, induce me to devote a final + chapter to its discussion." + +Now I am not aware that there is any misconception in any quarter as to +the essential teachings of Darwin's theory on this question. Surely it +is rather the case that there is a very general and very complete +understanding on this point, both by the friends and the foes of +Darwin's theory--so much so, indeed, that it is about the only point of +similar import in all Darwin's writings of which this can be said. Mr. +Wallace's "special views" on the other hand are, briefly stated, that +certain features, both of the morphology and the psychology of man, are +inexplicable by natural selection--or indeed by any other cause of the +kind ordinarily understood by the term natural: they can be explained +only by supposing "the intervention of some distinct individual +intelligence," which, however, need not necessarily be "one Supreme +Intelligence," but some other order of Personality standing anywhere in +"an infinite chasm between man and the Great Mind of the universe[13]." +Let us consider separately the corporeal and the mental peculiarities +which are given as justifying this important conclusion. + + [13] _Natural Selection and Tropical Nature_, p. 205; 1891. + +The bodily peculiarities are the feet, the hands, the brain, the voice, +and the naked skin. + +As regards the feet Mr. Wallace writes, "It is difficult to see why the +prehensile power [of the great toe] should have been taken away," +because, although "it may not be compatible with perfectly easy erect +locomotion," "how can we conceive that early man, _as an animal_, gained +anything by purely erect locomotion[14]?" But surely it is not difficult +to conceive this. In the proportion that our simian progenitors ceased +to be arboreal in their habits (and there may well have been very good +utilitarian reasons for such a change of habitat, analogous to those +which are known to have occurred in the phylogenesis of countless other +animals), it would clearly have been of advantage to them that their +already semi-erect attitude should have been rendered more and more +erect. To name one among several probabilities, the more erect the +attitude, and the more habitually it was assumed, the more would the +hands have been liberated for all the important purposes of +manipulation. The principle of the physiological division of labour +would thus have come more and more into play: natural selection would +therefore have rendered the upper extremities more and more suited to +the execution of these purposes, while at the same time it would have +more and more adapted the lower ones to discharging the sole function of +locomotion. For my own part, I cannot perceive any difficulty about +this: in fact, there is an admirable repetition of the process in the +ontogeny of our own children[15]. + + [14] _Ibid._ pp. 197-8. + + [15] For an excellent discussion on the ontogeny of the child in + this connexion, see _Some Laws of Heredity_, by Mr. S. S. + Buckman, pp. 290, _et seq._ (Proc. Cotteswold Nat. Field Club, + vol. x. p. 3, 1892). + +Next, with regard to the hand, Mr. Wallace says, that it "contains +latent capacities which are unused by savages, and must have been even +less used by palaeolithic man and his still ruder predecessors." Thus, +"it has all the appearance of an organ prepared for the use of civilized +man[16]." Even if this be true, however, it would surely be a dangerous +argument to rely upon, seeing that we cannot say of how much importance +it may have been for early man--or even apes--to have had their power of +manipulation progressively improved. But is the statement true? It +appears to me that if Mr. Wallace had endeavoured to imitate the +manufactures that were practised by "palaeolithic man," he would have +found the very best of reasons for cancelling his statement. For it is +an extremely difficult thing to chip a flint into the form of an +arrow-head: when made, the suitable attachment of it to a previously +prepared arrow is no easy matter: neither a bow nor a bow-string could +have been constructed by hands of much less perfection than our own: and +the slaying of game with the whole apparatus, when it has been +constructed, requires a manual dexterity which we may be perfectly +certain that Mr. Wallace--unless he has practised the art from +boyhood--does not possess. + + [16] _loc. cit._ p. 198. + +So it is with his similar argument that the human voice is more +"powerful," more "flexible," and presents a greater "range" and +"sweetness" than the needs of savage life can be held to require. The +futility of this argument is self-evident as regards "power." And +although its weakness is not so obvious with respect to the other three +qualities which are named, need we go further than the closely analogous +case of certain birds to show the precariousness of arguing from such +facts of organic nature to the special operation of "a superior +intelligence"? I can hardly suppose that Mr. Wallace will invoke any +such agency for the purpose of explaining the "latent capacities" of the +voice of a parrot. Yet, in many respects, these are even more wonderful +than those of the human voice, albeit in a wild state they are "never +required or used[17]." + + [17] For a discussion of this remarkable case, see _Mental Evolution + in Animals_, pp. 222-3. It appears to me that if Mr. Wallace's + argument from the "latent capacities of the voice of Man" is + good for anything, _a fortiori_ it must be taken to prove that, + in the case of the Parrot, "the organ has been prepared in + anticipation" of the amusement which the cultivation of its + latent capacities arouses in "civilized man." + +Once more, with regard to the naked skin, it seems sufficient to quote +the following passage from the first edition of the _Descent of Man_. + + "The Rev. T. R. Stebbing, in commenting on this view, remarks, that + had Mr. Wallace 'employed his usual ingenuity on the question of + man's hairless skin, he might have seen the possibility of its + selection through its superior beauty, or the health attaching to + superior cleanliness. At any rate it is surprising that he should + picture to himself a superior intelligence plucking the hair from + the backs of savage men (to whom, according to his own account, it + would have been useful and beneficial), in order that the + descendants of the poor shorn wretches might, after many deaths + from cold and damp in the course of many generations,' have been + forced to raise themselves in the scale of civilization through the + practice of various arts, in the manner indicated by Mr. + Wallace[18]." + + [18] _Descent of Man_, 1st Ed. ch. xx. (Trans. Dev. Assoc. for + Science, 1890). + +To this it may be added that the Chimpanzee "Sally" was largely denuded +of hair, especially on the back, or the part of "man's organization" on +which Mr. Wallace lays special stress, as being in this respect out of +analogy with other mammalia[19]. + + [19] The late Prof. Moseley informed me that, during his voyage on + the _Challenger_, he had seen many men whose backs were well + covered with hair.--For an excellent discussion of the whole + question, chiefly in the light of embryology, see the paper by + Buckman already alluded to, pp. 280-289. Also, for an account + of an extraordinary hairy race of men, see _Alone with the + Hairy Ainu_, by A. H. Savage Landor, 1893. + +Lastly, touching his statement that the brain of savage man is both +quantitatively and qualitatively in advance of his requirements, it is +here also sufficient to refer to Darwin's answer, as given in the +_Descent of Man_. Mr. Wallace, indeed, ignores this answer in his recent +re-publication of the argument; but it is impossible to understand why +he should have done so. To me, at all events, it seems that one out of +several considerations which Darwin advances is alone sufficient to show +the futility of this argument. I allude to the consideration that the +power of forming abstract ideas with the complex machinery of language +as the vehicle of their expression, is probably of itself enough to +account for both the mass and the structure of a savage's brain. But +this leads us to the second division of Mr. Wallace's argument, or that +derived from the mental endowments of mankind. + +Here the peculiarities called into evidence are, "the Mathematical +Faculty," "the Artistic Faculties," and "the Moral Sense." With regard +to the latter, he avows himself a member of the intuitional school of +ethics; but does not prove a very powerful advocate as against the +utilitarian[20]. + + [20] E.g. "The special faculties we have been discussing clearly + point to the existence in man of something which he has not + derived from his animal progenitors--something which we may + best refer to as being of a spiritual essence or nature, + capable of progressive development under favourable conditions. + On the hypothesis of this spiritual nature, superadded to the + animal nature of man, we are able to understand much that is + otherwise mysterious or unintelligible in regard to him, + especially the enormous influence of ideas, principles, and + beliefs over his whole life and action. Thus alone can we + understand the constancy of the martyr, the unselfishness of + the philanthropist, the devotion of the patriot, the enthusiasm + of the artist, and the resolute and persevering search of the + scientific worker after nature's secrets. Thus we may perceive + that the love of truth, the delight in beauty, the passion for + justice, and the thrill of exultation with which we hear of any + act of courageous self-sacrifice, are the workings within us of + a higher nature which has not been developed by means of the + struggle for material existence." (_Darwinism_, p. 474.) I have + quoted this whole paragraph, because it is so inconsistent with + the rest of Mr. Wallace's system that a mere epitome of it + might well have been suspected of error. Given an intellectual + being, howsoever produced, and what is there "mysterious or + unintelligible" in "the enormous influence of ideas, + principles, and beliefs over his whole life and action"? Or + again, if he be also a social being, what is the relevancy of + adducing "the constancy of the martyr," "the unselfishness of + the philanthropist," "the devotion of the patriot," "the love + of truth," "the passion for justice," "the thrill of exultation + when we hear of any act of courageous self-sacrifice," in + evidence _against_ the law of _utility_, or in order to prove + that a "nature" thus endowed has "_not_ been developed by means + of the struggle for existence," when once this struggle has + been transferred from individuals to communities? The whole + passage reads like an ironical satire in favour of "Darwinism," + rather than a serious argument against it. + +It comes, then, to this. According to Mr. Wallace's eventual +conclusion, man is to be separated from the rest of organic nature, and +the steady progress of evolution by natural causes is to be regarded as +stopped at its final stage, because the human mind presents the +faculties of mathematical calculation and aesthetic perception. Surely, +on antecedent grounds alone, it must be apparent that there is here no +kind of proportion between the conclusion and the _data_ from which it +is drawn. That we are not confined to any such grounds, I will now try +to show. + +Let it be remembered, however, that in the following brief criticism I +am not concerned with the issue as to whether, or how far, the +"faculties" in question have owed their origin or their development to +_natural selection_. I am concerned only with the doctrine that in order +to account for such and such particular "faculty" of the human mind, +some order of causation must be supposed other than what we call +natural. I am not a Neo-Darwinist, and so have no desire to make +"natural selection" synonymous with "natural causation" throughout the +whole domain of life and of mind. And I quite agree with Mr. Wallace +that, at any rate, the "aesthetic faculty" cannot conceivably have been +produced by natural selection--seeing that it is of no conceivable +life-serving value in any of the stages of its growth. Moreover, it +appears to me that the same thing has to be said of the play instincts, +sense of the ludicrous, and sundry other "faculties" of mind among the +lower animals. It being thus understood that I am not differing from Mr. +Wallace where he imposes "limits" on the powers of natural selection, +but only where he seems to take for granted that this is the same thing +as imposing limits on the powers of natural causation, my criticism is +as follows. + +In the first place, it is a psychological fallacy to regard the +so-called "faculties" of mind as analogous to "organs" of the body. To +classify the latter with reference to the functions which they severally +perform is to follow a natural method of classification. But it is an +artificial method which seeks to partition mental _faculty_ into this, +that, and the other mental _faculties_. Like all other purely artificial +classifications, this one has its practical uses; but, also like them, +it is destitute of philosophical meaning. This statement is so well +recognized by psychologists, that there is no occasion to justify it. +But I must remark that any cogency which Mr. Wallace's argument may +appear to present, arises from his not having recognized the fact which +the statement conveys. For, had he considered the mind as a whole, +instead of having contemplated it under the artificial categories of +constituent "faculties," he would probably not have laid any such +special stress upon some of the latter. In other words, he would have +seen that the general development of the human mind as a whole has +presumably involved the growth of those conventionally abstracted parts, +which he regards as really separate endowments. Or, if he should find it +easier to retain the terms of his metaphor, we may answer him by saying +that the "faculties" of mind are "correlated," like "organs" of the +body; and, therefore, that any general development of the various other +"faculties" have presumably entailed a collateral development of the two +in question. + +Again, in the second place, it would seem that Mr. Wallace has not +sufficiently considered the co-operation of either well-known natural +causes, which must have materially assisted the survival of the fittest +where these two "faculties" are concerned. For, even if we disregard the +inherited effects of use--which, however, if entertained as possible in +any degree at all, must have here constituted an important +factor,--there remain on the one hand, the unquestionable influences of +individual education and, on the other hand, of the selection principle +operating in the mind itself. + +Taking these two points separately, it is surely sufficiently well known +that individual education--or special training, whether of mind or +body--usually raises congenital powers of any kind to a more or less +considerable level above those of the normal type. In other words, +whatever doubt there may be touching the _inherited_ effects of use, +there can be no question touching the immense _developmental_ effects +thereof in the individual life-time. Now, the conditions of savage life +are not such as lead to any deliberate cultivation of the "faculties" +either of the mathematical or aesthetic order. Consequently, as might be +expected, we find both of them in what Mr. Wallace regards as but a +"latent" stage of development. But in just the same way do we find that +the marvellous powers of an acrobat when specially trained from +childhood--say to curve his spine backwards until his teeth can bite his +heels--are "latent" in all men. Or, more correctly, they are _potential +in every child_. So it is with the prodigious muscular development of a +trained athlete, and with any number of other cases where either the +body or the mind is concerned. Why then should Mr. Wallace select the +particular instances of the mathematical and aesthetic powers in savages +as in any special sense "prophetic" of future development in trained +members of civilized races? Although it is true that these "latent +capacities and powers are unused by savages," is it not equally true +that savages fail to use their latent capacities and powers as tumblers +and athletes? Moreover, is it not likewise true that _as_ used by +savages, or as occurring normally in man, such capacities and powers are +no less poorly developed than are those of the "faculties" on which Mr. +Wallace lays so much stress? In other words, are not "latent capacities +and powers" of all kinds more or less equally in excess of anything that +is ever required of them by man in a state of nature? Therefore, if we +say that where mathematics and the fine arts are concerned the potential +capacities of savage man are in some mystical sense "prophetic" of a +Newton or a Beethoven, so in consistency ought we to say that in these +same capacities we discern a similar prophecy of those other uses of +civilized life which we have in a rope-dancer or a clown. + +Again, and in addition to this, it should be remembered that, even if we +do suppose any prophecy of this kind where the particular capacities in +question are concerned, we must clearly extend the reference to the +lower animals. Not a few birds display aesthetic feelings in a measure +fairly comparable with those of savages; while we know that some animals +present the germs of a "faculty" of computation[21]. But, it is +needless to add, this fact is fatal to Mr. Wallace's argument as I +understand it--viz. that the "faculties" in question have been in some +special manner communicated by some superior intelligence to _man_. + + [21] See _Proc. Zool. Soc._ June 4, 1889, for an account of the + performances in this respect of the Chimpanzee "Sally." Also, + for some remarks on the psychology of the subject, in _Mental + Evolution in Man_, p. 215. I should like to take this + opportunity of stating that, after the two publications above + referred to, this animal's instruction was continued, and that, + before her death, her "counting" extended as far as ten. That + is to say, any number of straws asked for from one to ten would + always be correctly given. + +Once more, it is obviously unfair to select such men as a "Newton, a La +Place, a Gauss, or a Cayley" for the purpose of estimating the +difference between savages and civilized man in regard to the latter +"faculty." These men are the picked mathematicians of centuries. +Therefore they are men who not only enjoyed all the highest possible +benefits of individual culture, but likewise those who have been most +endowed with mathematical power congenitally. So to speak, they are the +best variations in this particular direction which our race is known to +have produced. But had such variations arisen among savages it is +sufficiently obvious that they could have come to nothing. Therefore, it +is the _normal average_ of "mathematical faculty" in civilized man that +should be contrasted with that of savage man; and, when due regard is +paid to the all-important consideration which immediately follows, I +cannot feel that the contrast presents any difficulty to the theory of +human evolution by natural causation. + +Lastly, the consideration just alluded to is, that civilized man enjoys +an advantage over savage man far in advance even of those which arise +from a settled state of society, incentives to intellectual training, +and so on. This inestimable advantage consists in the art of writing, +_and the consequent transmission of the effects of culture from +generation to generation_. Quite apart from any question as to the +hereditary transmission of acquired characters, we have in this +_intellectual_ transmission of acquired _experience_ a means of +accumulative cultivation quite beyond our powers to estimate. For, +unlike all other cases where we recognize the great influence of +individual use or practice in augmenting congenital "faculties" (such as +in the athlete, pianist, &c.), in this case the effects of special +cultivation do not end with the individual life, but are carried on and +on through successive generations _ad infinitum_. Hence, a civilized man +inherits mentally, if not physically, the effects of culture for ages +past, and this in whatever direction he may choose to profit therefrom. +Moreover--and I deem this an immensely important addition--in this +unique department of purely intellectual transmission, a kind of +non-physical natural selection is perpetually engaged in producing the +best results. For here a struggle for existence is constantly taking +place among "ideas," "methods," and so forth, in what may be termed a +psychological environment. The less fit are superseded by the more fit, +and this not only in the mind of the individual, but, through language +and literature, still more in the mind of the race. "A Newton, a La +Place, a Gauss, or a Cayley," would all alike have been impossible, but +for a previously prolonged course of mental evolution due to the +selection principle operating in the region of mathematics, by means of +continuous survivals of the best products in successive generations. +And, of course, the same remark applies to art in all its branches[22]. + + [22] In Prof. Lloyd Morgan's _Animal Life and Intelligence_ there is + an admirable discussion on this subject, which has been + published since the above was written. The same has to be said + of Weismann's Essay on Music, where much that I have here said + is anticipated. With the views and arguments which Mr. Mivart + has forcibly set forth I have already dealt to the best of my + ability in a work on _Mental Evolution in Man_. + +Quitting then the last, and in my opinion the weakest chapter of +_Darwinism_, the most important points presented by other portions of +this work are--to quote its author's own enumeration of them--an +attempted "proof that all specific characters are (or once have been) +either useful in themselves or correlated with useful characters": an +attempted "proof that natural selection can, in certain cases, increase +the sterility of crosses": an attempted "proof that the effects of use +and disuse, even if inherited, must be overpowered by natural +selection": an attempted proof that the facts of variation in nature are +in themselves sufficient to meet the difficulty which arises against the +theory of natural selection, as held by him, from the swamping effects +of free intercrossing: and, lastly, "a fuller discussion on the colour +relations of animals, with additional facts and arguments on the origin +of sexual differences of colour." As I intend to deal with all these +points hereafter, excepting the last, it will be sufficient in this +opening chapter to remark, that in as far as I disagree with Mr. Wallace +(and agree with Darwin), on the subject of "sexual differences of +colour," my reasons for doing so have been already sufficiently stated +in Part I. But there is much else in his treatment of this subject which +appears to me highly valuable, and therefore presenting an admirable +contribution to the literature of Darwinism. In particular, it appears +to me that the most important of his views in this connexion probably +represents the truth--namely, that, among the higher animals, more or +less conspicuous peculiarities of colour have often been acquired for +the purpose of enabling members of the same species quickly and +certainly to recognize one another. This theory was first published by +Mr. J. E. Todd, in 1888, and therefore but a short time before its +re-publication by Mr. Wallace. As his part in the matter has not been +sufficiently recognized, I should like to conclude this introductory +chapter by drawing prominent attention to the merits of Mr. Todd's +paper. For not only has it the merit of priority, but it deals with the +whole subject of "recognition colours"--or, as he calls them, "directive +colours"--in a more comprehensive manner than has been done by any of +his successors. In particular, he shows that the principle of +recognition-marking is not restricted to facilitating sexual +intercourse, but extends also to several other matters of importance in +the economy of animal life[23]. + + [23] _American Naturalist_, xxii. pp. 201-207. + + * * * * * + +Having thus briefly sketched the doctrines of the sundry Post-Darwinian +Schools from a general point of view, I shall endeavour throughout the +rest of this treatise to discuss in appropriate detail the questions +which have more specially come to the front in the post-Darwinian +period. It can scarcely be said that any one of these questions has +arisen altogether _de novo_ during this period; for glimmerings, more or +less conspicuous, of all are to be met with in the writings of Darwin +himself. Nevertheless it is no less true that only after his death have +they been lighted up to the full blaze of active discussion[24]. By far +the most important of them are those to which the rest of this treatise +will be confined. They are four in number, and it is noteworthy that +they are all intimately connected with the great question which Darwin +spent the best years of his life in contemplating, and which has +therefore, in one form or another, occupied the whole of the present +chapter--the question as to whether natural selection has been the sole +cause, or but the chief cause of modification. + + [24] It is almost needless to say that besides the works mentioned + in this chapter, many others have been added to the literature + of Darwinism since Darwin's death. But as none of these profess + to contain much that is original, I have not thought it + necessary to consider any of them in this merely general review + of the period in question. In subsequent chapters, however, + allusions will be made to those among them which I deem of most + importance. + + [Since this note was written and printed the following works + have been published to which it does not apply: _Animal Life + and Intelligence_, by Professor Lloyd Morgan; _The Colours of + Animals_, by Professor Poulton; and _Materials for the Study of + Variation_, by Mr. Bateson. All these works are of high value + and importance. Special reference should also be made to + Professor Weismann's Essays.] + +The four questions above alluded to appertain respectively to Heredity, +Utility, Isolation, and Physiological Selection. Of these the first two +will form the subject-matter of the present volume, while the last two +will be dealt with in the final instalment of _Darwin, and after +Darwin_. + + + + +SECTION I + +_HEREDITY_ + + + + +CHAPTER II. + +CHARACTERS AS HEREDITARY AND ACQUIRED (PRELIMINARY). + + +We will proceed to consider, throughout Section I of the present work, +the most important among those sundry questions which have come to the +front since the death of Darwin. For it was in the year after this event +that Weismann published the first of his numerous essays on the subject +of Heredity, and, unquestionably, it has been these essays which have +given such prominence to this subject during the last decade. + +At the outset it is desirable to be clear upon certain points touching +the history of the subject; the limits within which our discussion is to +be confined; the relation in which the present essay stands to the one +that I published last year under the title _An Examination of +Weismannism_; and several other matters of a preliminary kind. + +The problems presented by the phenomena of heredity are manifold; but +chief among them is the hitherto unanswered question as to the +transmission or non-transmission of acquired characters. This is the +question to which the present Section will be confined. + +Although it is usually supposed that this question was first raised by +Weismann, such was not the case. Any attentive reader of the successive +editions of Darwin's works may perceive that at least from the year 1859 +he had the question clearly before his mind; and that during the rest of +his life his opinion with regard to it underwent considerable +modifications--becoming more and more Lamarckian the longer that he +pondered it. But it was not till 1875 that the question was clearly +presented to the general public by the independent thought of Mr. +Galton, who was led to challenge the Lamarckian factors _in toto_ by way +of deduction from his theory of Stirp--the close resemblance of which to +Professor Weismann's theory of Germ-plasm has been shown in my +_Examination of Weismannism_. Lastly, I was myself led to doubt the +Lamarckian factors still further back in the seventies, by having found +a reason for questioning the main evidence which Mr. Darwin had adduced +in their favour. This doubt was greatly strengthened on reading, in the +following year, Mr. Galton's _Theory of Heredity_ just alluded to; and +thereupon I commenced a prolonged course of experiments upon the +subject, the general nature of which will be stated in future chapters. +Presumably many other persons must have entertained similar misgivings +touching the inheritance of acquired characters long before the +publication of Weismann's first essay upon the subject in 1883. The +question as to the inheritance of acquired characters was therefore +certainly not first raised by Weismann--although, of course, there is no +doubt that it was conceived by him independently, and that he had the +great merit of calling general attention to its existence and +importance. On the other hand, it cannot be said that he has succeeded +in doing very much towards its solution. It is for these reasons that +any attempt at dealing with Weismann's fundamental postulate--i.e. that +of the non-inheritance of acquired characters--was excluded from my +_Examination of Weismannism_. As there stated, he is justified in +assuming, for the purposes of his discussion, a negative answer to the +question of such inheritance; but evidently the question itself ought +not to be included within what we may properly understand by +"Weismannism." Weismannism, properly so called, is an elaborate system +of theories based on the fundamental postulate just mentioned--theories +having reference to the mechanism of heredity on the one hand, and to +the course of organic evolution on the other. Now it was the object of +the foregoing _Examination_ to deal with this system of theories _per +se_; and therefore we have here to take a new point of departure and to +consider separately the question of fact as to the inheritance or +non-inheritance of acquired characters. At first sight, no doubt, it +will appear that in adopting this method I am putting the cart before +the horse. For it may well appear that I ought first to have dealt with +the validity of Weismann's postulate, and not till then to have +considered the system of theories which he has raised upon it. But this +criticism is not likely to be urged by any one who is well acquainted +with the questions at issue. For, in the first place, it is notorious +that the question of fact is still open to question; and therefore it +ought to be considered separately, or apart from any theories which may +have been formed with regard to it. In the second place, our judgement +upon this question of fact must be largely influenced by the validity of +general reasonings, such as those put forward in the interests of rival +theories of heredity; and, as the theory of germ-plasm has been so +thoughtfully elaborated by Professor Weismann, I have sought to give it +the attention which it deserves as preliminary to our discussion of the +question of fact which now lies before us. Thirdly and lastly, even if +this question could be definitely answered by proving either that +acquired characters are inherited or that they are not, it would by no +means follow that Weismann's theory of heredity would be proved wholly +false in the one case, or wholly true in the other. That it need not be +wholly true, even were its fundamental postulate to be proved so, is +evident, because, although the fact might be taken to prove the theory +of Continuity, the theory of Germ-plasm is, as above stated, very much +more than this. That the theory of Germ-plasm need not be wholly false, +even if acquired characters should ever be proved heritable, a little +thought may easily show, because, in this event, the further question +would immediately arise as to the degrees and the comparative frequency +of such inheritance. For my own part, as stated in the _Examination_, I +have always been disposed to accept Mr. Galton's theory of Stirp in +preference to that of Germ-plasm on this very ground--i. e. that it does +not dogmatically exclude the possibility of an occasional inheritance of +acquired characters in faint though cumulative degrees. And whatever our +individual opinions may be touching the admissibility of such a _via +media_ between the theories of Pangenesis and Germ-plasm, at least we +may all agree on the desirability of fully considering the matter as a +preliminary to the discussion of the question of fact. + +As it is not to be expected that even those who may have read my +previous essay can now carry all these points in their memories, I will +here re-state them in a somewhat fuller form. + +The following diagram will serve to give a clearer view of the sundry +parts of Professor Weismann's system of theories, as well as of their +relations to one another. + +[Illustration: Postulate as to the absolute non-inheritance of acquired +characters.] + +Now, as just explained, the parts of this system which may be properly +and distinctively called "Weismannism" are those which go to form the +Y-like structure of deductions from the fundamental postulate. +Therefore, it was the Y-like system of deductions which were dealt with +in the _Examination of Weismannism_, while it is only his basal +postulate which has to be dealt with in the following chapters. + +So much, then, for the relations of Weismann's system of theories to one +another. It is, however, of even more importance that we should gain a +clear view of the relations between his theory of _heredity_ to those of +Darwin and of Galton, as preliminary to considering the fundamental +question of fact. + +As we have already seen, the theory of germ-plasm is not only a theory +of heredity: it is also, and more distinctively, a theory of evolution, +&c. As a theory of heredity it is grounded on its author's fundamental +postulate--the _continuity_ of germ-plasm. But as a theory of evolution, +it requires for its support this additional postulate, that the +continuity of germ-plasm has been _absolute_ "since the first origin of +life." It is clear that this additional postulate is not needed for his +theory of heredity, but only for his additional theory of evolution, &c. +There have been one or two other theories of heredity, prior to this +one, which, like it, have been founded on the postulate of Continuity of +the substance of heredity; but it has not been needful for any of these +theories to postulate further that this substance has been _always_ thus +isolated, or even that it is now _invariably_ so. For even though the +isolation be frequently invaded by influences of body-changes on the +congenital characters of this substance, it does not follow that this +principle of Continuity may not still be true _in the main_, even +although it is supplemented in some degree by that of use-inheritance. +Indeed, so far as the phenomena of heredity are concerned, it is +conceivable that all congenital characters were originally acquired, +and afterwards became congenital on account of their long inheritance. I +do not myself advocate this view as biologically probable, but merely +state it as logically possible, and in order to show that, so far as the +phenomena of heredity are concerned, there appears to be no reason for +Weismann's deduction that the principle of Continuity, if true at all, +must be _absolute_. And it would further appear, the only reason why he +makes this deduction (stem of the Y) is in order to provide a foundation +for his further theories of evolution, &c. (arms of the Y). It is indeed +necessary for these further theories that body-changes should never +exercise any hereditary influence on the hereditary endowments of +germ-plasm, and therefore it is that he posits the substance of heredity +as, not only continuous, but uninterruptably so "since the first origin +of life." + +Now, this may be made more clear by briefly comparing Weismann's theory +with those of Darwin and of Galton. Weismann's theory of heredity, then, +agrees with its predecessors which we are considering in all the +following respects. The substance of heredity is particulate; is mainly +lodged in highly specialized cells; is nevertheless also distributed +throughout the general cellular tissues, where it is concerned in all +processes of regeneration, repair, and a-sexual reproduction; presents +an enormously complex structure, in that every constituent part of a +potentially future organism is represented in a fertilized ovum by +corresponding particles; is everywhere capable of virtually unlimited +multiplication, without ever losing its hereditary endowments; is often +capable of carrying these endowments in a dormant state through a long +series of generations until at last they reappear in what we recognize +as recursions. Thus far all three theories are in agreement. In fact, +the only matter of any great importance wherein they disagree has +reference to the doctrine of Continuity[25]. For while Darwin's theory +supposes the substance of heredity to be mainly formed anew in each +ontogeny, and therefore that the continuity of this substance is for the +most part interrupted in every generation[26], Weismann's theory +supposes this substance to be formed only during the phylogeny of each +species, and therefore to have been absolutely uninterrupted since the +first origin of life. + + [25] Originally, Weismann's further assumption as to the perpetual + stability of germ-plasm, "since the first origin of sexual + reproduction," was another very important point of difference, + but this has now been withdrawn. + + [26] I say "_mainly_ formed anew," and "_for the most part_ + interrupted," because even Darwin's theory does not, as is + generally supposed, exclude the doctrine of Continuity _in + toto_. + +But now, Galton's theory of heredity stands much nearer to Weismann's in +this matter of Continuity; for it is, as he says, a theory of "modified +pangenesis," and the modification consists in allowing very much more +for the principle of Continuity than is allowed by Darwin's theory; in +fact he expresses himself as quite willing to adopt (on adequate grounds +being shown) the doctrine of Continuity as absolute, and therefore +propounded, as logically possible, the identical theory which was +afterwards and independently announced by Weismann. Or, to quote his own +words-- + + "We might almost reserve our belief that the structural [i. e. + somatic] cells can react on the sexual elements at all, and we may + be confident that at most they do so in a very faint degree; in + other words, that acquired modifications are barely, if at all, + _inherited_, in the correct sense of that word[27]." + + [27] _Theory of Heredity_ (Journ. Anthrop. Inst. 1875, p. 346). + +So far Mr. Galton; but for Weismann's further theory of evolution, &c., +it is necessary to postulate the additional doctrine in question; and it +makes a literally immeasurable difference to any theory of evolution +whether or not we entertain this additional postulate. For no matter how +faintly or how fitfully the substance of heredity may be modified by +somatic tissues, the Lamarckian principles are hypothetically allowed +some degree of play. And although this is a lower degree than Darwin +supposed, their influence in determining the course of organic evolution +may still have been enormous; seeing that their action in any degree +must always have been _directive_ of variation on the one hand, and +_cumulative_ on the other. + +Thus, by merely laying this theory side by side with Weismann's we can +perceive at a glance how a _pure_ theory of _heredity_ admits of being +based on the postulate of Continuity alone, without cumbering itself by +any further postulate as to this Continuity being _absolute_. And this, +in my opinion is the truly scientific attitude of mind for us to adopt +as preliminary to the following investigation. For the whole +investigation will be concerned--and concerned only--with this question +of Continuity as absolute, or as admitting of degrees. There is, without +any question, abundant evidence to prove that the substance of heredity +is at least partly continuous (Gemmules). It may be that there is also +abundant evidence to prove this substance much more _largely_ +continuous than Darwin supposed (Stirp); but be this as it may, it is +certain that any such question as to the _degree_ of continuity differs, +_toto caelo_, from that as to whether there can ever be any continuity +at all. + +How, then, we may well ask, is it that so able a naturalist and so clear +a thinker as Weismann can have so far departed from the inductive +methods as to have not merely propounded the question touching +Continuity and its degrees, or even of Continuity as absolute; but to +have straightway assumed the latter possibility as a basis on which to +run a system of branching and ever-changing speculations concerning +evolution, variation, the ultimate structure of living material, the +intimate mechanism of heredity, or, in short, such a system of deductive +conjectures as has never been approached in the history of science? The +answer to this question is surely not far to seek. Must it not be the +answer already given? Must it not have been for the sake of rearing this +enormous structure of speculation that Weismann has adopted the +assumption of Continuity as absolute? As we have just seen, Galton had +well shown how a theory of heredity could be founded on the general +doctrine of Continuity, without anywhere departing from the inductive +methods--even while fully recognizing the possibility of such continuity +as absolute. But Galton's theory was a "_Theory of Heredity_," and +nothing more. Therefore, while clearly perceiving that the Continuity in +question _may_ be absolute, he saw no reason, either in fact or in +theory, for concluding that it _must_ be. On the contrary, he saw that +this question is, for the present, necessarily unripe for profitable +discussion--and, _a fortiori_, for the shedding of clouds of seed in all +the directions of "Weismannism." + +Hence, what I desire to be borne in mind throughout the following +discussion is, that it will have exclusive reference to the question of +fact already stated, without regard to any superjacent theories; and, +still more, that there is a vast distinction between any question +touching the degrees in which acquired characters are transmitted to +progeny, and the question as to whether they are ever transmitted in any +degree at all. Now, the latter question, being of much greater +importance than the former, is the one which will mainly occupy our +attention throughout the rest of this Section. + +We have already seen that before the subject was taken up by Weismann +the difference between acquired and congenital characters in respect to +transmissibility was generally taken to be one of degree; not one of +kind. It was usually supposed that acquired characters, although not so +fully and not so certainly inherited as congenital characters, +nevertheless were inherited in some lesser degree; so that if the same +acquired character continued to be successively acquired in a number of +sequent generations, what was at first only a slight tendency to be +inherited would become by summation a more and more pronounced tendency, +till eventually the acquired character might become as strongly +inherited as a congenital one. Or, more precisely, it was supposed that +an acquired character, in virtue of such a summation of hereditary +influence, would in time become congenital. Now, if this supposition be +true, it is evident that more or less assistance must be lent to +natural selection in its work of evolving adaptive modifications[28]. +And inasmuch as we know to what a wonderful extent adaptive +modifications are secured during individual life-times--by the direct +action of the environment on the one hand, and by increased or +diminished use of special organs and mental faculties on the other--it +becomes obvious of what importance even a small measure of +transmissibility on their part would be in furnishing to natural +selection ready-made variations in required directions, as distinguished +from promiscuous variations in all directions. Contrariwise, if +functionally-produced adaptations and adaptations produced by the direct +action of the environment are never transmitted in any degree, not only +would there be an incalculable waste, so to speak, of adaptive +modifications--these being all laboriously and often most delicately +built up during life-times of individuals only to be thrown down again +as regards the interest of species--but so large an additional burden +would be thrown upon the shoulders of natural selection that it becomes +difficult to conceive how even this gigantic principle could sustain it, +as I shall endeavour to show more fully in future chapters. On the other +hand, however, Weismann and his followers not only feel no difficulty in +throwing overboard all this ready-made machinery for turning out +adaptive modifications when and as required; but they even represent +that by so doing they are following the logical maxim, _Entia non sunt +multiplicanda praeter necessitatem_--which means, in its relation to +causality, that we must not needlessly multiply hypothetical principles +to explain given results. But when appeal is here made to this logical +principle--the so-called Law of Parsimony--two things are forgotten. + + [28] Mr. Platt Ball has, indeed, argued that "use-inheritance would + often be an evil," since, for example, "the condyle of the + human jaw would become larger than the body of the jaw, because + as the fulcrum of the lever it receives more pressure"; and + similarly as regards many other hypothetical cases which he + mentions. (_The Effects of Use and Disuse_, pp. 128-9 _et + seq._) But it is evident that this argument proves too much. + For if the effects of use and disuse as transmitted to progeny + would be an evil, it could only be because these effects as + they occur in the parents are an evil--and this they most + certainly are not, being, on the contrary and as a general + rule, of a high order of adaptive value. Moreover, in the race, + there is a superadded agency always at work, which must + effectually prevent any undue accumulation of these + effects--namely, natural selection, which every Darwinist + accepts as a controlling principle of all or any other + principles of change. Therefore, if, as first produced in the + life-time of individuals, the effects of use and disuse are not + injurious, much less can they become so if transmitted through + the life-time of species. Again, Mr. Wallace argues that, even + supposing use-inheritance to occur, its adapting work in the + individual can never extend to the race, seeing that the + natural selection of fortuitous variations in the directions + required must always produce the adaptations _more quickly_ + than would be possible by use-inheritance. This argument, being + one of more weight, will be dealt with in a future chapter. + +In the first place, it is forgotten that the very question in debate is +whether causes of the Lamarckian order _are_ unnecessary to explain all +the phenomena of organic nature. Of course if it could be proved that +the theory of natural selection alone is competent to explain all these +phenomena, appeal to the logical principle in question would be +justifiable. But this is precisely the point which the followers of +Darwin refuse to accept; and so long as it remains the very point at +issue, it is a mere begging the question to represent that a class of +causes which have hitherto been regarded as necessary are, in fact, +unnecessary. Or, in other words, when Darwin himself so decidedly held +that these causes are necessary as supplements to natural selection, the +burden of proof is quite as much on the side of Weismann and his +followers to show that Darwin's opinion was wrong, as it is on the side +of Darwin's followers to show that it was right. Yet, notwithstanding +the elaborate structure of theory which Weismann has raised, there is +nowhere one single fact or one single consideration of much importance +to the question in debate which was not perfectly well known to Darwin. +Therefore I say that all this challenging of Darwinists to justify their +"Lamarckian assumptions" really amounts to nothing more than a pitting +of opinion against opinion, where there is at least as much call for +justification on the one side as on the other. + +Again, when these challenges are thrown down by Weismann and his +followers, it appears to be forgotten that the conditions of their own +theory are such as to render acceptance of the gauge a matter of great +difficulty. The case is very much like that of a doughty knight pitching +his glove into the sea, and then defying any antagonist to take it up. +That this is the case a very little explanation will suffice to show. + +The question to be settled is whether acquired characters are ever +transmitted by heredity. Now suppose, for the sake of argument, that +acquired characters are transmitted by heredity--though not so fully and +not so certainly as congenital characters--how is this fact to be proved +to the satisfaction of Weismann and his followers? First of all they +answer,--Assuredly by adducing experimental proof of the inheritance of +injuries, or mutilations. But in making this answer they appear to +forget that Darwin has already shown its inefficiency. That the +self-styled Neo-Lamarckians have been much more unguarded in this +respect, I fully admit; but it is obviously unfair to identify Darwin's +views with those of a small section of evolutionists, who are really as +much opposed to Darwin's teaching on one side as is the school of +Weismann on the other. Yet, on reading the essays of Weismann +himself--and still more those of his followers--one would almost be led +to gather that it is claimed by him to have enunciated the distinction +between congenital and acquired characters in respect of +transmissibility; and therefore also to have first raised the objection +which lies against the theory of Pangenesis in respect of the +non-transmissibility of mutilations. In point of fact, however, Darwin +is as clear and decided on these points as Weismann. And his answer to +the obvious difficulty touching the non-transmissibility of mutilations +is, to quote his own words, "the long-continued inheritance of a part +which has been removed during many generations is no real anomaly, for +gemmules formerly derived from the part are multiplied and transmitted +from generation to generation[29]." Therefore, so far as Darwin's theory +is concerned, the challenge to produce evidence of the transmission of +injuries is irrelevant: it is no more a part of Darwin's theory than it +is of Weismann's to maintain that injuries _are_ transmitted. + + [29] _Variation under Domestication_, ii. 392. + +There is, however, one point in this connexion to which allusion must +here be made. Although Darwin did not believe in the transmissibility +of mutilations when these consist merely in the amputation of parts of +an organism, he did believe in a probable tendency to transmission when +removal of the part is followed by gangrene. For, as he says, in that +case, all the gemmules of the mutilated or amputated part, as they are +gradually attracted to that part (in accordance with the law of affinity +which the theory assumes), will be successively destroyed by the morbid +process. Now it is of importance to note that Darwin made this exception +to the general rule of the non-transmissibility of mutilations, not +because his theory of pangenesis required it, but because there appeared +to be certain very definite observations and experiments--which will be +mentioned later on--proving that when mutilations are followed by +gangrene they are apt to be inherited: his object, therefore, was to +reconcile these alleged facts with his theory, quite as much as to +sustain his theory by such facts. + +So much, then, for the challenge to produce direct evidence of the +transmissibility of acquired characters, so far as mutilations are +concerned: believers in Darwin's theory, as distinguished from +Weismann's, are under no obligation to take up such a challenge. But the +challenge does not end here. Show us, say the school of Weismann, a +single instance where an acquired character _of any kind_ (be it a +mutilation or otherwise) has been inherited: this is all that we +require: this is all that we wait for: and surely, unless it be +acknowledged that the Lamarckian doctrine reposes on mere assumption, at +least one such case ought to be forthcoming. Well, nothing can sound +more reasonable than this in the first instance; but as soon as we +begin to cast about for cases which will satisfy the Neo-Darwinians, we +find that the structure of their theory is such as to preclude, in +almost every conceivable instance, the possibility of meeting their +demand. For their theory begins by assuming that natural selection is +the one and only cause of organic evolution. Consequently, what their +demand amounts to is throwing upon the other side the burden of +disproving this assumption--or, in other words, of proving the negative +that in any given case of transmitted adaptation natural selection has +_not_ been the sole agent at work. Now, it must obviously be in almost +all cases impossible to prove this negative among species in a state of +nature. For, even supposing that among such species Lamarckian +principles have had a large share in the formation of hereditary and +adaptive characters, how would Weismann himself propose that we should +set about the proof of such a fact, where the proof demanded by his +assumption is, that the _abstract possibility_ of natural selection +having had anything to do with the matter must be excluded? Obviously +this is impossible in the case of inherited characters which are also +_adaptive_ characters. How then does it fare with the case of inherited +characters which are not also adaptive? Merely that this case is met by +another and sequent assumption, which constitutes an integral part of +the Neo-Darwinian creed--namely, that in nature there _can be no such +characters_. Seeing that natural selection is taken to be the only +possible cause of change in species, it follows that all changes +occurring in species must necessarily be adaptive, whether or not we are +able to perceive the adaptations. In this way apparently useless +characters, as well as obviously useful ones, are ruled out of the +question: that is to say, _all_ hereditary characters of species in a +state of nature are _assumed_ to be due to natural selection, and then +it is demanded that the validity of this assumption should be disproved +by anybody who doubts it. Yet Weismann himself would be unable to +suggest any conceivable method by which it can be disproved among +species in a state of nature--and this even supposing that the +assumption is entirely false[30]. + + [30] In subsequent chapters, especially devoted to the question + (i.e. Section II), the validity of this assumption will be + considered on its own merits. + +Consequently, the only way in which these speciously-sounding challenges +can be adequately met is by removing some individuals of a species from +a state of nature, and so from all known influences of natural +selection; then, while carefully avoiding artificial selection, causing +these individuals and their progeny through many generations unduly to +exercise some parts of their bodies, or unduly to fail in the exercise +of others. But, clearly, such an experiment is one that must take years +to perform, and therefore it is now too early in the day to reproach the +followers of Darwin with not having met the challenges which are thrown +down by the followers of Weismann[31]. + + [31] I say "the followers of Weismann," because Weismann himself, + with his clear perception of the requirements of experimental + research, expressly states the above considerations, with the + conclusions to which they lead. Nevertheless, he is not + consistent in his utterances upon this matter; for he + frequently expresses himself to the effect, "that the _onus + probandi_ rests with my opponents, and therefore they ought to + bring forward actual proofs" (_Essays_, i. p. 390). But, as + above shown, the _onus_ rests as much with him as with his + opponents; while, even if his opponents are right, he elsewhere + recognizes that they can bring "actual proofs" of the fact only + as a result of experiments which must take many years to + perform. + +Probably enough has now been said to show that the Neo-Darwinian +assumption precludes the possibility of its own disproof from any of the +facts of nature (as distinguished from domestication)--and this even +supposing that the assumption be false. On the other hand, of course, it +equally precludes the possibility of its own proof; and therefore it is +as idle in Darwinists to challenge Weismann for proof of his negative +(i. e. that acquired characters are not transmitted), as it is in +Weismann to challenge Darwinists for proof of the opposite negative (i. +e. that all seeming cases of such transmission are not due to natural +selection). This dead-lock arises from the fact that in nature it is +beyond the power of the followers of Darwin to exclude the abstract +possibility of natural selection in any given case, while it is equally +beyond the power of the followers of Weismann to exclude the abstract +possibility of Lamarckian principles. Therefore at present the question +must remain for the most part a matter of opinion, based upon general +reasoning as distinguished from special facts or crucial experiments. +The evidence available on either side is presumptive, not +demonstrative[32]. But it is to be hoped that in the future, when time +shall have been allowed for the performance of definite experiments on a +number of generations of domesticated plants or animals, intentionally +shielded from the influences of natural selection while exposed to those +of the Lamarckian principles, results will be gained which will finally +settle the question one way or the other. + + [32] Note A. + +Meanwhile, however, we must be content with the evidence as it stands; +and this will lead us to the second division of our subject. That is to +say, having now dealt with the antecedent, or merely logical, state of +the question, we have next to consider what actual, or biological, +evidence there is at present available on either side of it. Thus far, +neither side in the debate has any advantage over the other. On grounds +of general reasoning alone they both have to rely on more or less +dogmatic assumptions. For it is equally an unreasoned statement of +opinion whether we allege that all the phenomena of organic evolution +can be, or can not be, explained by the theory of natural selection +alone. We are at present much too ignorant touching the causes of +organic evolution to indulge in dogmatism of this kind; and if the +question is to be referred for its answer to authority, it would appear +that, both in respect of number and weight, opinions on the side of +having provisionally to retain the Lamarckian factors are more +authoritative than those _per contra_[33]. + + [33] For a fair and careful statement of the present balance of + authoritative opinion upon the question, see H. F. Osborn, + _American Naturalist_, 1892, pp. 537-67. + + * * * * * + +Turning then to the question of fact, with which the following chapters +are concerned, I will conclude this preliminary one with a few words on +the method of discussion to be adopted. + +First I will give the evidence in favour of Lamarckianism; this will +occupy the next two chapters. Then, in Chapter V, I will similarly give +the evidence _per contra_, or in favour of Continuity as absolute. +Lastly, I will sum up the evidence on both sides, and give my own +judgement on the whole case. But on whichever side I am thus acting as +special pleader for the time being, I will adduce only such arguments as +seem to me valid--excluding alike from both the many irrelevant or +otherwise invalid reasonings which have been but too abundantly +published. Moreover, I think it will be convenient to consider all that +has been said--or may be said--in the way of criticism to each argument +by the opposite side while such argument is under discussion--i. e. not +to wait till all the special pleading on one side shall have been +exhausted before considering the exceptions which have been (or admit of +being) taken to the arguments adduced, but to deal with such exceptions +at the time when each of these arguments shall have been severally +stated. Again, and lastly, I will arrange the evidence in each case--i. +e. on both sides--under three headings, viz. (A) Indirect, (B) Direct, +and (C) Experimental[34]. + + [34] [The above paragraph is allowed to remain exactly as Mr. + Romanes left it. Chapters V and VI were however not completed. + _See_ note appended to Preface. C. Ll. M.] + + + + +CHAPTER III. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(A.) +_Indirect Evidence in favour of the Inheritance of Acquired Characters._ + + +Starting with the evidence in favour of the so-called Lamarckian +factors, we have to begin with the Indirect--and this without any +special reference to the theories, either of Weismann or of others. + +It has already been shown, while setting forth in the preceding chapter +the antecedent standing of the issue, that in this respect the _prima +facie_ presumption is wholly on the side of the transmission, in greater +degree or less, of acquired characters. Even Weismann allows that all +"_appearances_" point in this direction, while there is no inductive +evidence of the action of natural selection in any one case, either as +regards germs or somas, and therefore, _a fortiori_, of the +"all-sufficiency" of this cause[35]. It is true that in some of his +earlier essays he has argued that there is no small weight of _prima +facie_ evidence in favour of his own views as to the non-inheritance of +acquired characters. This, however, will have to be considered in its +proper place further on. Meanwhile I shall say merely in general terms +that it arises almost entirely from a confusion of the doctrine of +Continuity as absolute with that of Continuity as partial, and +therefore, as admitting of degrees in different cases--which, as already +explained, are doctrines wide as the poles asunder. But, leaving aside +for the present such _prima facie_ evidence as Weismann has adduced on +his side of the issue, I may quote him as a hostile witness to the +weight of this kind of evidence _per contra_, in so far as it has +already been presented in the foregoing chapter. Indeed, Weismann is +much too logical a thinker not to perceive the cogency of the +"appearances" which lie against his view of Continuity as +absolute--although he has not been sufficiently careful in +distinguishing between such Continuity and that which admits of degrees. + + [35] See, especially, his excellent remarks on this point, _Contemp. + Rev._ Sept. 1893. + +We may take it, then, as agreed on all hands that whatever weight merely +_prima facie_ evidence may in this matter be entitled to, is on the side +of what I have termed moderated Lamarckianism: first sight "appearances" +are against the Neo-Darwinian doctrine of the absolute non-inheritance +of acquired characters. + + * * * * * + +Let us now turn to another and much more important line of indirect +evidence in favour of moderated Lamarckianism. + +The difficulty of _excluding the possibility_ of natural selection +having been at work in the case of wild plants and animals has already +been noticed. Therefore we may now appreciate the importance of all +facts or arguments which _attenuate the probability_ of natural +selection having been at work. This may be done by searching for cases +in nature where a congenital structure, although unquestionably +adaptive, nevertheless presents so small an amount of adaptation, that +we can scarcely suppose it to have been arrived at by natural selection +in the struggle for existence, as distinguished from the inheritance of +functionally-produced modifications. For if functionally-produced +modifications are ever transmitted at all, there is no limit to the +minuteness of adaptive values which may thus become congenital; whereas, +in order that any adaptive structure or instinct should be seized upon +and accumulated by natural selection, it must from the very first have +had an adaptive value sufficiently great to have constituted its +presence a matter of life and death in the struggle for existence. Such +structures or instincts must not only have always presented some measure +of adaptive value, but this must always have been sufficiently great to +reach what I have elsewhere called a selection-value. Hence, if we meet +with cases in nature where adaptive structures or instincts present so +low a degree of adaptive value that it is difficult to conceive how they +could ever have exercised any appreciable influence in the battle for +life, such cases may fairly be adduced in favour of the Lamarckian +theory. For example, the Neo-Lamarckian school of the United States is +chiefly composed of palaeontologists; and the reason of this seems to be +that the study of fossil forms--or of species in process of +formation--reveals so many instances of adaptations which in their +nascent condition present such exceedingly minute degrees of adaptive +value, that it seems unreasonable to attribute their development to a +survival of the fittest in the complex struggle for existence. But as +this argument is in my opinion of greatest force when it is applied to +certain facts of physiology with which I am about to deal, I will not +occupy space by considering any of the numberless cases to which the +Neo-Lamarckians apply it within the region of palaeontology[36]. + + [36] There is now an extensive literature within this region. The + principal writers are Cope, Scott and Osborn. Unfortunately, + however, the facts adduced are not crucial as test-cases + between the rival theories--nearly all of them, in fact, being + equally susceptible of explanation by either. + +Turning then to inherited actions, it is here that we might antecedently +expect to find our best evidence of the Lamarckian principles, if these +principles have really had any share in the process of adaptive +evolution. For we know that in the life-time of individuals it is +action, and the cessation of action, which produce nearly all the +phenomena of acquired adaptation--use and disuse in animals being merely +other names for action and the cessation of action. Again, we know that +it is where neuro-muscular machinery is concerned that we meet with the +most conclusive evidence of the remarkable extent to which action is +capable of co-ordinating structures for the ready performance of +particular functions; so that even during the years of childhood +"practice makes perfect" to the extent of organizing neuro-muscular +adjustments, so elaborate and complete as to be indistinguishable from +those which in natural species we recognized as reflex actions on the +one hand, and instinctive actions on the other. Hence, if there be any +such thing as "use-inheritance" at all, it is in the domain of reflex +actions and instinctive actions that we may expect to find our best +evidence of the fact. Therefore I will restrict the present line of +evidence--(A)--to these two classes of phenomena, as together yielding +the best evidence obtainable within this line of argument. + + * * * * * + +The evidence in favour of the Lamarckian factors which may be derived +from the phenomena of reflex action has never, I believe, been pointed +out before; but it appears to me of a more cogent nature than perhaps +any other. In order to do it justice, I will begin by re-stating an +argument in favour of these factors which has already been adduced by +previous writers, and discussed by myself in published correspondence +with several leaders of the ultra-Darwinian school. + +Long ago Professor Broca and Mr. Herbert Spencer pointed to the facts of +co-adaptation, or co-ordination within the limits of the same organism, +as presenting good evidence of Lamarckian principles, working in +association with natural selection. Thus, taking one of Lamarck's own +illustrations, Mr. Spencer argued that there must be numberless +changes--extending to all the organs, and even to all the tissues, of +the animal--which in the course of many generations have conspired to +convert an antelope into a giraffe. Now the point is, that throughout +the entire history of these changes their utility must always have been +dependent on their association. It would be useless that an incipient +giraffe should present the peculiar form of the hind-quarters which we +now perceive, unless at the same time it presented the correspondingly +peculiar form of the fore-quarters; and as each of these great +modifications entails innumerable subordinate modifications throughout +both halves of the creature concerned, the chances must have been +infinitely great against the required association of so many changes +happening to have arisen congenitally in the same individuals by way of +merely fortuitous variation. Yet, if we exclude the Lamarckian +interpretation, which gives an intelligible _cause_ of co-ordination, we +are required to suppose that such a happy concurrence of innumerable +independent variations must have occurred by mere accident--and this on +innumerable different occasions in the bodies of as many successive +ancestors of the existing species. For at each successive stage of the +improvement natural selection (if working alone) must have needed all, +or at any rate most, of the co-ordinated parts to occur in the same +individual organisms[37]. + + [37] For another and better illustration more recently published by + Mr. Spencer, see _The Inadequacy of Natural Selection_, p. 22. + +In alluding to what I have already published upon the difficulty which +thus appears to be presented to his theory, Weismann says, "At no +distant time I hope to be able to consider this objection, and to show +that the apparent support given to the old idea [i. e. of the +transmission of functionally-produced modifications] is really insecure, +and breaks down as soon as it is critically examined[38]." + + [38] _Essays on Heredity_, vol. i. p. 389. + + [For further treatment of the subject under discussion _see_ + Weismann, _The All-sufficiency of Natural Selection_ (Contemp. + Rev. Sept. and Oct. 1893), and _The Effect of External + Influences upon Development_. "Romanes Lecture" 1894, and + Spencer, _Weismannism once more_ (Cont. Rev. Oct. 1894). C. Ll. + M.] + +So much for what Weismann has said touching this matter. But the matter +has also been dealt with both by Darwin and by Wallace. Darwin very +properly distinguishes between the fallacy that "with animals such as +the giraffe, of which the whole structure is admirably co-ordinated for +certain purposes, it has been supposed that all the parts must have been +simultaneously modified[39]," and the sound argument that the +co-ordination itself cannot have been due to natural selection alone. +This important distinction may be rendered more clear as follows. + + [39] _Variation_, &c., vol. ii. p. 206. + +The facts of artificial selection prove that immense modifications of +structure may be caused by a cumulative blending in the same individuals +of characters which were originally distributed among different +individuals. Now, in the parallel case of natural selection the +characters thus blended will usually--if not invariably--be of an +adaptive kind; and their eventual blending together in the same +individuals will be due to free intercrossing of the most fit. But this +_blending of adaptations_ is quite a different matter from the +_occurrence of co-ordination_. For it belongs to the essence of +co-ordination that each of the co-ordinated parts should be destitute of +adaptive value _per se_: the adaptation only begins to arise if all the +parts in question occur associated together in the same individuals +_from the very first_. In this case it is obvious that the analogy of +artificial selection can be of no avail in explaining the facts, since +the difficulty presented has nothing to do with the blending in single +individuals of adaptations previously distributed among different +individuals; it has to do with the simultaneous appearance in single +individuals of a co-adaptation of parts, none of which could ever have +been of any adaptive value had it been previously distributed among +different individuals. Consequently, where Darwin comes to consider this +particular case (or the case of co-adaptation as distinguished from the +blending of adaptations), he freely invokes the aid of the Lamarckian +principles[40]. + + [40] E. g. _Origin of Species_, p. 178. + +Wallace, on the other hand, refuses to do this, and says that "the best +answer to the difficulty" of supposing natural selection to have been +the only cause of co-adaptation may be "found in the fact that the very +thing said to be impossible by variation and natural selection, has been +again and again affected by variation and artificial selection[41]." +This analogy (which Darwin had already and very properly adduced with +regard to the _blending of adaptations_) he enforces by special +illustrations; but he does not appear to perceive that it misses the +whole and only point of the "difficulty" against which it is brought. +For the case which his analogy sustains is not that which Darwin, +Spencer, Broca and others, mean by _co-adaptation_: it is the case of a +blending of _adaptations_. It is not the case where adaptation is _first +initiated in spite of intercrossing_, by a fortuitous concurrence of +variations each in itself being without adaptive value: it is the case +where adaptation is _afterwards increased by means of intercrossing_, +through the blending of variations each of which has always been in +itself of adaptive value. + + [41] _Darwinism_, p. 418. + +From this I hope it will be apparent that the only way in which the +"difficulty" from co-adaptation can be logically met by the +ultra-Darwinian school, is by denying that the phenomenon of +co-adaptation (as distinguished from the blending of adaptations) is +ever to be really met with in organic nature. It may be argued that in +all cases where co-adaptation _appears_ to occur, closer examination +will show that the facts are really due to a blending of adaptations. +The characters A + B + C + D, which are now found united in the same +organism, and, as thus united, all conspiring to a common end, may +originally have been distributed among different organisms, where they +_severally_ subserved some other ends--or possibly the same end, though +in a less efficient manner. Obviously, however, in this case their +subsequent combination in the same organism would not be an instance of +co-adaptation, but merely of an advantageous blending together of +already existing adaptations. This argument, or rejoinder, has in point +of fact been adopted by Professor Meldola, he believes that all cases of +seeming co-adaptation are thus due to a mere blending of +adaptations[42]. Of course, if this position can be maintained, the +whole difficulty from co-adaptation would lapse. But even then it would +lapse on the ground of _fact_. It would not have been overturned, or in +any way affected, by Wallace's _argument_ from artificial selection. +For, in that event, no such argument would be required, and, if adduced, +would be irrelevant, since no one has ever alleged that there is any +difficulty in understanding the mere confluence of adaptations by +free-intercrossing of the best adapted. + + [42] _Nature_, vol. xliii. pp. 410, 557; vol. xliv. pp. 7, 29. I say + "adopted," because I had objected to his quoting the analogy of + artificial selection, and stated, as above, that the only way + to meet Mr. Spencer's "difficulty" was to deny the fact of + co-adaptation as ever occurring in any case. It then appeared + that Professor Meldola agreed with me as to this. But I do not + yet understand why, if such were his view, he began by + endorsing Mr. Wallace's analogy from artificial selection--i. + e. confusing the case of co-adaptation with that of the + blending of adaptations. If any one denies the fact of + co-adaptation, he cannot assist his denial by arguing the + totally different fact that adaptations may be blended by free + intercrossing; for this latter fact has never been questioned, + and has nothing to do with the one which he engaged in + disputing. + +Now, if we are agreed that the only question in debate is the question +of fact whether or not co-adaptation ever occurs in nature, it appears +to me that the best field for debating the question is furnished by the +phenomena of reflex action. I can well perceive that the instances +adduced by Broca and Spencer in support of their common argument--such +as the giraffe, the elk, &c.--are equivocal. But I think that many +instances which may be adduced of reflex action are much more to the +point. _For it belongs to the very nature of reflex action that it +cannot work unless all parts of the machinery concerned are already +present, and already co-ordinated, in the same organism._ It would be +useless, in so far as such action is concerned if the afferent and +efferent nerves, the nerve-centre, and the muscles organically grouped +together, were not all present from the very first in the same +individuals, and from the very first were not co-ordinated as a definite +piece of organic machinery. + +With respect to reflex actions, therefore, it is desirable to begin by +pointing out how widely the adaptations which they involve differ from +those where no manufacture, so to speak, of special machinery is +required. Thus, it is easy to understand how natural selection alone is +capable of gradually accumulating congenital variations in the direction +of protective colouring; of mimicry; of general size, form, mutual +correlation of parts as connected with superior strength, fleetness, +agility, &c.; of greater or less development of particular parts, such +as legs, wings, tails, &c. For in all such cases the adaptation which is +in process of accumulation is from its very commencement and throughout +each of its subsequent stages, of _use_ in the struggle for existence. +And inasmuch as all the individuals of each successive generation vary +round the specific mean which characterized the preceding generation, +there will always be a sufficient number of individuals which present +congenital variations of the kind required for natural selection to +seize upon, without danger of their being swamped by free +intercrossing--as Mr. Wallace has very ably shown in his _Darwinism_. +But this law of averages can apply only to cases where single +structures--or a single group of correlated structures--are already +present, and already varying round a specific mean. The case is quite +different where a _co-ordination_ of structures is required for the +performance of a _previously non-existent_ reflex action. For some, at +least, of these structures must be _new_, as must also be the function +which all of them first conspire to perform. Therefore, neither the new +elements of structure, nor the new combination of structures, can have +been previously given as varying round a specific mean. On the contrary, +a very definite piece of machinery, consisting of many co-ordinated +parts, must somehow or other be originated in a high degree of working +efficiency, before it can be capable of answering its purpose in the +prompt performance of a particular action under particular circumstances +of stimulation. Lastly, such pieces of machinery are always of a highly +delicate character, and usually involve so immensely complex a +co-ordination of mutually dependent parts, that it is only a +physiologist who can fully appreciate the magnitude of the distinction +between "adaptations" of this kind, and "adaptations" of the kind which +arise through natural selection seizing upon congenital variations as +these oscillate round a specific mean. + +Or the whole argument may be presented in another form, under three +different headings, thus:-- + +In the first place, it will be evident from what has just been said, +that such a piece of machinery as is concerned in even the simplest +reflex action cannot have occurred in any considerable number of +individuals of a species, _when it first began to be constructed_. On +the contrary, if its _origin_ were dependent on congenital variations +alone, the needful co-adaptation of parts which it requires can scarcely +have happened to occur in more than a very small percentage of +cases--even if it be held conceivable that by such means alone it should +ever have occurred at all. Hence, instead of preservation and subsequent +improvement having taken place _in consequence of_ free intercrossing +among all individuals of the species (as in the cases of protective +colouring, &c., where adaptation has no reference to any mechanical +co-adaptation of parts), they must have taken place _in spite of_ such +intercrossing. + +In the second place, adaptations due to organic machineries of this kind +differ in another all-important respect from those due to a summation of +adaptive characters which are already present and already varying round +a specific mean. The latter depend for their summation upon the +fact--not merely, as just stated, that they are already present, already +varying round a specific mean, and therefore owe their progressive +evolution to free intercrossing, but also--_that they admit of very +different degrees of adaptation_. It is only because the degree of +adaptation in generation B is superior to that in generation A that +_gradual improvement_ in respect of adaptation is here possible. In the +case of protective resemblance, for example, a very imperfect and merely +accidental resemblance to a leaf, to another insect, &c., may at the +first start have conferred a sufficient degree of adaptive imitation to +count for something in the struggle for life; and, if so, the basis +would be given for a progressive building up by natural selection of +structures and colours in ever-advancing degrees of adaptive +resemblance. There is here no necessity to suppose--nor in point of fact +is it ever supposed, since the supposition would involve nothing short +of a miracle--that such extreme perfection in this respect as we now so +frequently admire has originated suddenly in a single generation, as a +collective variation of a congenital kind affecting simultaneously a +large proportional number of individuals. But in the case of a reflex +mechanism--which may involve even greater marvels of adaptive +adjustment, and _all_ the parts of which must occur in the same +_individuals_ to be of any use--it _is_ necessary to suppose some such +sudden and collective origin in some very high degree of efficiency, if +natural selection has been the only principle concerned in afterwards +perfecting the mechanism. For it is self-evident that a reflex action, +from its very nature, cannot admit of any great differences in its +degrees of adaptation: if it is to work at all, so as to count for +anything in the struggle for life, it must already be given in a state +of working efficiency. So that, unless we invoke either the doctrine of +"prophetic types" or the theory of sudden creations, I confess I do not +see how we are to explain either the origin, or the development, of a +reflex mechanism by means of natural selection alone. + +Lastly, in the third place, _even when reflex mechanisms have been fully +formed_, it is often beyond the power of sober credence to believe that +they now are, or ever can have been, of selective value in the struggle +for existence, as I will show further on. And such cases go to fortify +the preceding argument. For if not conceivably of selective value even +when completely evolved, much less can they conceivably have been so +through all the stages of their complex evolution back to their very +origin. Therefore, supposing for the present that there are such cases +of reflex action in nature, neither their origin nor their development +can conceivably have been due to natural selection alone. The Lamarckian +factors, however, have no reference to degrees of adaptation, any more +than they have to degrees of complexity. No question of value, as +selective or otherwise, can obtain in their case: neither in their case +does any difficulty obtain as regards the co-adaptation of severally +useless parts. + +Now, if all these distinctions between the Darwinian and Lamarckian +principles are valid--and I cannot see any possibility of doubt upon +this point--strong evidence in favour of the latter would be furnished +by cases (if any occur) where structures, actions, instincts, &c., +although of some adaptive value, are nevertheless plainly not of +selective value. According to the ultra-Darwinian theory, no such cases +ought ever to occur: according to the theory of Darwin himself, they +ought frequently to occur. Therefore a good test, or criterion, as +between these different theories of organic evolution is furnished by +putting the simple question of fact--Can we, or can we not, show that +there are cases of adaptation where the degree of adaptation is so small +as to be incompatible with the supposition of its presenting a selective +value? And if we put the wider question--Are there any cases where the +co-adaptation of severally useless parts has been brought about, when +even the resulting whole does not present a selective value?--then, of +course, we impose a still more rigid test. + +Well, notwithstanding the difficulty of proving such a negative as the +absence of natural selection where adaptive development is concerned, I +believe that there are cases which conform to both these tests +simultaneously; and, moreover, that they are to be found in most +abundance where the theory of use-inheritance would most expect them to +occur--namely, in the province of reflex action. For the very essence of +this theory is the doctrine, that constantly associated use of the same +parts for the performance of the same action will progressively organize +those parts into a reflex mechanism--no matter how high a degree of +co-adaptation may thus be reached on the one hand, or how low a degree +of utilitarian value on the other. + +Having now stated the general or abstract principles which I regard as +constituting a defence of the Lamarckian factors, so far as this admits +of being raised on grounds of physiology, we will now consider a few +concrete cases by way of illustration. It is needless to multiply such +cases for the mere purpose of illustration. For, on reading those here +given, every physiologist will at once perceive that they might be added +to indefinitely. The point to observe is, the relation in which these +samples of reflex action stand to the general principles in question; +for there is nothing unusual in the samples themselves. On the contrary, +they are chosen because they are fairly typical of the phenomena of +reflex action in general. + +In our own organization there is a reflex mechanism which ensures the +prompt withdrawal of the legs from any source of irritation supplied to +the feet. For instance, even after a man has broken his spine in such a +manner as totally to interrupt the functional continuity of his spinal +cord and brain, the reflex mechanism in question will continue to +retract his legs when his feet are stimulated by a touch, a burn, &c. +This responsive action is clearly an adaptive action, and, as the man +neither feels the stimulation nor the resulting movement, it is as +clearly a reflex action. The question now is as to the mode of its +origin and development. + +I will not here dwell upon the argument from co-adaptation, because this +may be done more effectually in the case of more complicated reflex +actions, but will ask whether we can reasonably hold that this +particular reflex action--comparatively simple though it is--has ever +been of selective value to the human species, or to the ancestors +thereof? Even in its present fully-formed condition it is fairly +questionable whether it is of any adaptive _value_ at all. The movement +performed is no doubt an adaptive _movement_; but is there any occasion +upon which the reflex mechanism concerned therein can ever have been of +adaptive _use_? Until a man's legs have been paralyzed as to their +voluntary motion, he will always promptly withdraw his feet from any +injurious source of irritation by means of his conscious intelligence. +True, the reflex mechanism secures an almost inappreciable saving in the +time of response to a stimulus, as compared with the time required for +response by an act of will; but the difference is so exceedingly small, +that we can hardly suppose the saving of it in this particular case to +be a matter of any adaptive--much less selective--importance. Nor is it +more easy to suppose that the reflex mechanism has been developed by +natural selection for the purpose of replacing voluntary action when the +latter has been destroyed or suspended by grave spinal injury, +paralysis, coma, or even ordinary sleep. In short, even if for the sake +of argument we allow it to be conceivable that any single human being, +ape, or still more distant ancestor, has ever owed its life to the +possession of this mechanism, we may still be certain that not one in a +million can have done so. And, if this is the case with regard to the +mechanism as now fully constructed, still more must it have been the +case with regard to all the previous stages of construction. For here, +without elaborating the point, it would appear that a process of +construction by survival of the fittest alone is incomprehensible. + +On the other hand, of course, the theory of use-inheritance furnishes a +fully intelligible--whether or not a true--explanation. For those +nerve-centres in the spinal cord which co-ordinate the muscles required +for retracting the feet are the centres used by the will for this +purpose. And, by hypothesis, the frequent use of them for this purpose +under circumstances of stimulation which render the muscular response +appropriate, will eventually establish an organic connexion between such +response and the kind of stimulation to which it is appropriate--even +though there be no utilitarian reason for its establishment[43]. To +invert a phrase of Aristotle, we do not frequently use this mechanism +because we have it (seeing that in our normal condition there is no +necessity for such use); but, by hypothesis, we have it because we have +frequently used its several elements in appropriate combination. + + [43] It may be said, with regard to this particular reflex, that it + may perhaps be, so to speak, a mechanical accident, arising + from the contiguity of the sensory and motor roots in the cord. + But as this suggestion cannot apply to other reflexes presently + to be adduced, it need not be considered. + +I will adduce but one further example in illustration of these general +principles--passing at once from the foregoing case of comparative +simplicity to one of extreme complexity. + +There is a well-known experiment on a brainless frog, which reveals a +beautiful reflex mechanism in the animal, whereby the whole body is +enabled continually to readjust its balance on a book (or any other +plane surface), as this is slowly rotated on a horizontal axis. So long +as the book is lying flat, the frog remains motionless; but as soon as +the book is tilted a little, so that the frog is in danger of slipping +off, all the four feet begin to crawl up the hill; and the steeper the +hill becomes, the faster they crawl. When the book is vertical, the frog +has reached the now horizontal back, and so on. Such being the facts, +the question is--How can the complicated piece of machinery thus implied +have been developed by natural selection? Obviously it cannot have been +so by any of the parts concerned having been originally distributed +among different individuals, and afterwards united in single individuals +by survival (i.e. free intercrossing) of the fittest. In other words, +the case is obviously one of co-adaptation, and not one of the blending +of adaptations. Again, and no less obviously, it is impossible that the +co-adaptation can have been _gradually developed_ by natural selection, +because, in order to have been so, it must by hypothesis have been of +some degree of use in every one of its stages; yet it plainly cannot +have been until it had been fully perfected in all its astonishing +complexity[44]. + + [44] Of course it will be observed that the question is not with + regard to the development of all the nerves and muscles + concerned in this particular process. It is as to the + development of the co-ordinating centres, which thus so + delicately respond to the special stimuli furnished by + variations of angle to the horizon. And it is as inconceivable + in this case of reflex action, as it is in almost every other + case of reflex action, that the highly specialized machinery + required for performing the adaptive function can ever have had + its origin in the performance of any other function. Indeed, a + noticeable peculiarity of reflex mechanisms as a class is the + highly specialized character of the functions which their + highly organized structures subserve. + +Lastly, not only does it thus appear impossible that during all stages +of its development--or while as yet incapable of performing its +intricate function--this nascent mechanism can have had any adaptive +value; but even as now fully developed, who will venture to maintain +that it presents any selective value? As long as the animal preserves +its brain, it will likewise preserve its balance, by the exercise of its +intelligent volition. And, if the brain were in some way destroyed, the +animal would be unable to breed, or even to feed; so that natural +selection can never have had any _opportunity_, so to speak, of +developing this reflex mechanism in brainless frogs. On the other hand, +as we have just seen, we cannot perceive how there can ever have been +any _raison d'être_ for its development in normal frogs--even if its +development were conceivably possible by means of this agency. But if +practice makes perfect in the race, as it does in the individual, we can +immediately perceive that the constant habit of correctly adjusting its +balance may have gradually developed, in the batrachian organization, +this non-necessary reflex[45]. + + [45] We meet with a closely analogous reflex mechanism in brainless + vertebrata of other kinds; but these do not furnish such good + test cases, because the possibility of natural selection cannot + be so efficiently attenuated. The perching of brainless birds, + for instance, at once refers us to the roosting of sleeping + birds, where the reflex mechanism concerned is clearly of high + adaptive value. Therefore such a case is not available as a + test, although the probability is that birds have inherited + their balancing mechanisms from their sauropsidian ancestors, + where it would have been of no such adaptive importance. + +And, of course, this example--like that of withdrawing the feet from a +source of stimulation, which a frog will do as well as a man--does not +stand alone. Without going further a-field than this same animal, any +one who reads, from our present point of view, Goltz's work on the +reflex actions of the frog, will find that the great majority of +them--complex and refined though most of them are--cannot conceivably +have ever been of any use to any frog that was in undisturbed possession +of its brain. + +Hence, not to occupy space with a reiteration of facts all more or less +of the same general kind, and therefore all presenting identical +difficulties to ultra-Darwinian theory, I shall proceed to give two +others which appear to me of particular interest in the present +connexion, because they furnish illustrations of reflex actions in a +state of only partial development, and are therefore at the present +moment demonstrably useless to the animal which displays them. + +Many of our domesticated dogs, when we gently scratch their sides and +certain other parts of the body, will themselves perform scratching +movements with the hind leg of the same side as that upon which the +irritation is being supplied. According to Goltz[46], this action is a +true reflex; for he found that it is performed equally well in a dog +which has been deprived of its cerebral hemispheres, and therefore of +its normal volition. Again, according to Haycraft[47], this reflex is +congenital, or not acquired during the life-time of each individual dog. +Now, although the action of scratching is doubtless adaptive, it appears +to me incredible that it could ever have become organized into a +congenital reflex by natural selection. For, in order that it should, +the scratching away fleas would require to have been a function of +selective value. Yet, even if the irritation caused by fleas were +supposed to be so far fatal in the struggle for existence, it is certain +that they would always be scratched away by the conscious intelligence +of each individual dog; and, therefore, that no advantage could be +gained by organizing the action into a reflex. On the other hand, if +acquired characters are ever in any degree transmitted, it is easy to +understand how so frequently repeated an action should have become, in +numberless generations of dogs, congenitally automatic. + + [46] _Pflüger's Archiv_, Bd. xx. s. 23 (1879). + + [47] _Brain_, part xlviii, pp. 516-19 (1889).--There is still better + proof of this in the case of certain rodents. For instance, + observing that rats and mice are under the necessity of very + frequently scratching themselves with their hind-feet, I tried + the experiment of removing the latter from newly-born + individuals--i.e. before the animals were able to co-ordinate + their movements, and therefore before they had ever even + attempted to scratch themselves. Notwithstanding that they were + thus destitute of individual experience with regard to the + benefit of scratching, they began their scratching movements + with their stumps as soon as they were capable of executing + co-ordinated movements, and afterwards continued to do so till + the end of their lives with as much vigour and frequency as + unmutilated animals. Although the stumps could not reach the + seats of irritation which were bent towards them, they used to + move rapidly in the air for a time sufficient to have given the + itching part a good scratch, had the feet been present--after + which the animals would resume their sundry other avocations + with apparent satisfaction. These facts showed the hereditary + response to irritation by parasites to be so strong, that even + a whole life-time's experience of its futility made no + difference in the frequency or the vigour thereof. + +So much for the general principle of selective value as applied to this +particular case. And similarly, of course, we might here repeat the +application of all the other general principles, which have just been +applied in the two preceding cases. But it is only one of these other +general principles which I desire in the present case specially to +consider, for the purpose of considering more closely than hitherto the +difficulty which this principle presents to ultra-Darwinian theory. + +The difficulty to which I allude is that of understanding how all the +stages in the _development_ of a reflex action can have been due to +natural selection, seeing that, before the reflex mechanism has been +sufficiently elaborated to perform its function, it cannot have +presented any degree of utility. Now the particular force of the present +example, the action of scratching--as also of the one to +follow--consists in the fact that it is a case where a reflex action is +not yet completely organized. It appears to be only in course of +construction, so that it is neither invariably present, nor, when it is +present, is it ever fully adapted to the performance of its function. + +That it is not invariably present (when the brain is so) may be proved +by trying the simple experiment on a number of puppies--and also of +full-grown dogs. Again, that even when it is present it is far from +being fully adapted to the performance of its function, may be proved by +observing that only in rare instances does the scratching leg succeed in +scratching the place which is being irritated. The movements are made +more or less at random, and as often as not the foot fails to touch the +body at any place at all. Hence, although we have a "prophecy" of a +reflex action well designed for the discharge of a particular function, +at present the machinery is not sufficiently perfected for the adequate +discharge of that function. In this important respect it differs from +the otherwise closely analogous reflex action of the frog, whereby the +foot of the hind leg is enabled to localize with precision a seat of +irritation on the side of the body. But this beautiful mechanism in the +frog cannot have sprung into existence ready formed at any historical +moment in the past history of the phyla. It must have been the subject +of a more or less prolonged evolution, in some stage of which it must +presumably have resembled the now nascent scratching reflex of the dog, +in making merely abortive attempts at localizing the seat of +irritation--supposing, of course, that some physiologist had been there +to try the experiment by first removing the brain. Now, even if one +could imagine it to be, either in the frog or in the dog, a matter of +selective importance that so exceedingly refined a mechanism should have +been developed for the sole purpose of inhibiting the bites of +parasites--which in every normal animal would certainly be discharged by +an _intentional_ performance of the movements in question,--even if, in +order to save an hypothesis at all costs, we make so violent a +supposition as this, still we should do so in vain. For it would still +remain undeniably certain that the reflex mechanism is _not_ of any +selective value. Even now the mechanism in the dog is not sufficiently +precise to subserve the only function which occasionally and abortively +it attempts to perform. Thus it has all the appearance of being but an +imitating shadow of certain neuro-muscular adjustments, which have been +habitually performed in the canine phyla by a volitional response to +cutaneous irritation. Were it necessary, this argument might be +strengthened by observing that the reflex action is positively +_improved_ by removal of the brain. + +The second example of a nascent reflex in dogs which I have to mention +is as follows. + +Goltz found that his brainless dogs, when wetted with water, would shake +themselves as dry as possible, in just the same way as normal dogs will +do under similar circumstances. This, of course, proves that the shaking +movements may be performed by a reflex mechanism, which can have no +other function to perform in the organization of a dog, and which, +besides being of a highly elaborate character, will respond only to a +very special kind of stimulation. Now, here also I find that the +mechanism is congenital, or not acquired by individual experience. For +the puppies on which I experimented were kept indoors from the time of +their birth--so as never to have had any experience of being wetted by +rain, &c.--till they were old enough to run about with a full power of +co-ordinating their general movements. If these young animals were +suddenly plunged into water, the shock proved too great: they would +merely lie and shiver. But if their feet alone were wetted, by being +dipped in a basin of water, the puppies would soon afterwards shake +their heads in the peculiar manner which is required for shaking water +off the ears, and which in adult dogs constitutes the first phase of a +general shaking of the whole body. + +Here, then, we seem to have good evidence of all the same facts which +were presented in the case of the scratching reflex. In the first +place, co-adaptation is present in a very high degree, because this +shaking reflex in the dog, unlike the skin-twitching reflex in the +horse, does not involve only a single muscle, or even a single group of +muscles; it involves more or less the co-ordinated activity of many +voluntary muscles all over the body. Such, at any rate, is the case when +the action is performed by the intelligent volition of an adult dog; and +if a brainless dog, or a young puppy, does not perform it so extensively +or so vigorously, this only goes to prove that the reflex has not yet +been sufficiently developed to serve as a substitute for intelligent +volition--i.e. that it is _useless_, or a mere organic shadow of the +really adaptive substance. Again, even if this nascent reflex had been +so far developed as to have been capable of superseding voluntary +action, still we may fairly doubt whether it could have proved of +selective value. For it is questionable whether the immediate riddance +of water after a wetting is a matter of life and death to dogs in a +state of nature. Moreover, even if it were, every individual dog would +always have got rid of the irritation, and so of the danger, by means of +a _voluntary_ shake--with the double result that natural selection has +never had any opportunity of gradually building up a special reflex +mechanism for the purpose of securing a shake, and that the canine race +have not had to wait for any such unnecessary process. Lastly, such a +process, besides being unnecessary, must surely have been, under any +circumstances, impossible. For even if we were to suppose--again for the +sake of saving an hypothesis at any cost--that the presence of a +fully-formed shaking reflex is of selective value in the struggle for +existence, it is perfectly certain that all the stages through which the +construction of so elaborate a mechanism must have passed could not have +been, under any circumstances, of any such value. + +But, it is needless to repeat, according to the hypothesis of +use-inheritance, there is no necessity to suppose that these incipient +reflex mechanisms _are_ of any value. If function produces structure in +the race as it does in the individual, the voluntary and frequently +repeated actions of scratching and shaking may very well have led to an +organic integration of the neuro-muscular mechanisms concerned. Their +various parts having been always co-ordinated for the performance of +these actions by the intelligence of innumerable dogs in the past, their +co-adapted activity in their now automatic responses to appropriate +stimuli presents no difficulty. And the consideration that neither in +their prospectively more fully developed condition, nor, _a fortiori_, +in their present and all previous stages of evolution, can these reflex +mechanisms be regarded as presenting any selective--or even so much as +any adaptive--value, is neither more nor less than the theory of +use-inheritance would expect. + +Thus, with regard to the phenomena of reflex action in general, all the +facts are such as this theory requires, while many of the facts are such +as the theory of natural selection alone cannot conceivably explain. +Indeed, it is scarcely too much to say, that most of the facts are such +as directly contradict the latter theory in its application to them. +But, be this as it may, at present there are only two hypotheses in the +field whereby to account for the facts of adaptive evolution. One of +these hypotheses is universally accepted, and the only question is +whether we are to regard it as _alone_ sufficient to explain _all_ the +facts. The other hypothesis having been questioned, we can test its +validity only by finding cases which it is fully capable of explaining, +and which do not admit of being explained by its companion hypothesis. I +have endeavoured to show that we have a large class of such cases in the +domain of reflex action, and shall next endeavour to show that there is +another large class in the domain of instinct. + + * * * * * + +If instinct be, as Professor Hering, Mr. Samuel Butler, and others have +argued, "hereditary habit"--i. e. if it comprises an element of +transmitted experience--we at once find a complete explanation of many +cases of the display of instinct which otherwise remain inexplicable. +For although a large number--or even, as I believe, a large majority--of +instincts are explicable by the theory of natural selection alone, or by +supposing that they were gradually developed by the survival of +fortuitous variations in the way of advantageous psychological +peculiarities, this only applies to comparatively simple instincts, such +as that of a protectively coloured animal exhibiting a preference for +the surroundings which it resembles, or even adopting attitudes in +imitation of objects which occur in such surroundings. But in all cases +where instincts become complex and refined, we seem almost compelled to +accept Darwin's view that their origin is to be sought in consciously +intelligent adjustments on the part of ancestors. + +Thus, to give only one example, a species of Sphex preys upon +caterpillars, which it stings in their nerve-centres for the purpose of +paralyzing, without killing them. The victims, when thus rendered +motionless, are then buried with the eggs of the Sphex, in order to +serve as food for her larvae which subsequently develop from these eggs. +Now, in order thus to paralyze a caterpillar, the Sphex has to sting it +successively in nine minute and particular points along the ventral +surface of the animal--and this the Sphex unerringly does, to the +exclusion of all other points of the caterpillar's anatomy. Well, such +being the facts--according to M. Fabre, who appears to have observed +them carefully--it is conceivable enough, as Darwin supposed[48], that +the ancestors of the Sphex, being like many other hymenopterous insects +highly intelligent, should have observed that on stinging caterpillars +in these particular spots a greater amount of effect was produced than +could be produced by stinging them anywhere else; and, therefore, that +they habitually stung the caterpillars in these places only, till, in +course of time, this originally intelligent habit became by heredity +instinctive. But now, on the other hand, if we exclude the possibility +of this explanation, it appears to me incredible that such an instinct +should ever have been evolved at all; for it appears to me incredible +that natural selection, unaided by originally intelligent action, could +ever have developed such an instinct out of merely fortuitous +variations--there being, by hypothesis, nothing to _determine_ +variations of an insect's mind in the direction of stinging caterpillars +only in these nine intensely localized spots[49]. + + [48] For details of his explanation of this particular case, for + which I particularly inquired, see _Mental Evolution in + Animals_, pp. 301-2. + + [49] Note B. + +Again, there are not a few instincts which appear to be wholly useless +to their possessors, and others again which appear to be even +deleterious. The dusting over of their excrement by certain +freely-roaming carnivora; the choice by certain herbivora of particular +places on which to void their urine, or in which to die; the howling of +wolves at the moon; purring of cats, &c., under pleasurable emotion; and +sundry other hereditary actions of the same apparently unmeaning kind, +all admit of being readily accounted for as useless habits originally +acquired in various ways, and afterwards perpetuated by heredity, +because not sufficiently deleterious to have been stamped out by natural +selection[50]. But it does not seem possible to explain them by survival +of the fittest in the struggle for existence. + + [50] For fuller treatment see _Mental Evolution in Animals_, pp. + 274-285, 378-379, 381-383. + +Finally, in the case of our own species, it is self-evident that the +aesthetic, moral, and religious instincts admit of a natural and easy +explanation on the hypothesis of use-inheritance, while such is by no +means the case if that hypothesis is rejected. Our emotions of the +ludicrous, of the beautiful, and of the sublime, appear to be of the +nature of hereditary instincts; and be this as it may, it would further +appear that, whatever else they may be, they are certainly not of a +life-preserving character. And although this cannot be said of the +moral sense when the theory of natural selection is extended from the +individual to the tribe, still, when we remember the extraordinary +complexity and refinement to which they have attained in civilized man, +we may well doubt whether they can have been due to natural selection +alone. But space forbids discussion of this large and important question +on the present occasion. Suffice it therefore to say, that I doubt not +Weismann himself would be the first to allow that his theory of heredity +encounters greater difficulties in the domain of ethics than in any +other--unless, indeed, it be that of religion[51]. + + [51] For an excellent essay on the deleterious character of early + forms of religion from a biological point of view, see the Hon. + Lady Welby, _An Apparent Paradox in Mental Evolution_ (Journ. + Anthrop. Inst. May 1891). + + * * * * * + +I have now given a brief sketch of the indirect evidence in favour of +the so-called Lamarckian factors, in so far as this appears fairly +deducible from the facts of reflex action and of instinct. It will now +be my endeavour to present as briefly what has to be said against this +evidence. + +As previously observed, the facts of reflex action have not been +hitherto adduced in the present connexion. This has led me to occupy +considerably more space in the treatment of them than those of instinct. +On this account, also, there is here nothing to quote, or to consider, +_per contra_. On the other hand, however, Weismann has himself dealt +with the phenomena of instinct in animals, though not, I think, in +man--if we except his brilliant essay on music. Therefore let us now +begin this division of our subject by briefly stating, and considering, +what he has said upon the subject. + +The answer of Weismann to difficulties which arise against the +ultra-Darwinian theory in the domain of instinct, is as follows:-- + + "The necessity for extreme caution in appealing to the supposed + hereditary effects of use, is well shown in the case of those + numerous instincts which only come into play once in a life-time, + and which do not therefore admit of improvement by practice. The + queen-bee takes her nuptial flight only once, and yet how many and + complex are the instincts and the reflex mechanisms which come into + play on that occasion. Again, in many insects the deposition of + eggs occurs but once in a life-time, and yet such insects always + fulfil the necessary conditions with unfailing accuracy[52]." + + [52] _Essays_, i. p. 93. + +But in this rejoinder the possibility is forgotten, that although such +actions are _now_ performed only once in the individual life-time, +_originally_--i.e. when the instincts were being developed in a remote +ancestry--they may have been performed on many frequent and successive +occasions during the individual life-time. In all the cases quoted by +Weismann, instincts of the kind in question bear independent evidence of +high antiquity, by occurring in whole genera (or even families), by +being associated with peculiar and often highly evolved structures +required for their performance, and so on. Consequently, in these cases +ample time has been allowed for subsequent changes of habit, and of +seasonal alterations with respect to propagation--both these things +being of frequent and facile occurrence among animals of all kinds, even +within periods which fall under actual observation. Nevertheless, I do +not question that there are instinctive activities which, as far as we +are able to see, can never have been performed more than once in each +individual life-time[53]. The fact, however, only goes to show what is +fully admitted--that some instincts (and even highly complex instincts) +have apparently been developed by natural selection alone. Which, of +course, is not equivalent to showing that all instincts must have been +developed by natural selection alone. The issue is not to be debated on +general grounds like this, but on those of particular cases. Even if it +were satisfactorily proved that the instincts of a queen-bee have been +developed by natural selection, it would not thereby be proved that such +has been the case with the instincts of a Sphex wasp. One can very well +understand how the nuptial flight of the former, with all its associated +actions, may have been brought about by natural selection alone; but +this does not help us to understand how the peculiar instincts of the +latter can have been thus caused. + + [53] See _Mental Evolution in Animals_, pp. 377-8. + +Strong evidence in favour of Weismann's views does, however, at first +sight seem to be furnished by social hymenoptera in other respects. For +not only does the queen present highly specialized and altogether +remarkable instincts; but the neuters present totally different and even +still more remarkable instincts--which, moreover, are often divided into +two or more classes, corresponding with the different "castes." Yet the +neuters, being barren females, never have an opportunity of bequeathing +their instincts to progeny. Thus it appears necessary to suppose that +the instincts of all the different castes of neuters are latent in the +queen and drones, together with the other instincts which are patent in +both. Lastly, it seems necessary to suppose that all this wonderful +organization of complex and segregated instincts must have been built up +by natural selection acting exclusively on the queens and drones--seeing +that these exercise their own instincts only once in a life-time, while, +as just observed, the neuters cannot possibly bequeath their individual +experience to progeny. Obviously, however, natural selection must here +be supposed to be operating at an immense disadvantage; for it must have +built up the often diverse and always complex instincts of neuters, not +directly, but indirectly through the queens and drones, which never +manifest any of these instincts themselves. + +Now Darwin fully acknowledged the difficulty of attributing these +results to the unaided influence of natural selection; but the fact of +neuter insects being unable to propagate seemed to him to leave no +alternative. And so it seems to Weismann, who accordingly quotes these +instincts in support of his views. And so it seemed to me, until my work +on _Animal Intelligence_ was translated into French, and an able Preface +was supplied to that translation by M. Perrier. In this Preface it is +argued that we are not necessarily obliged to exclude the possibility of +Lamarckian principles having operated in the original formation of these +instincts. On the contrary, if such principles ever operate at all, +Perrier shows that here we have a case where it is virtually certain +that they must have operated. For although neuter insects are now unable +to propagate, their organization indicates--if it does not actually +prove--that they are descended from working insects which were able to +propagate. Thus, in all probability, what we now call a "hive" was +originally a society of sexually mature insects, all presenting the same +instincts, both as to propagation and to co-operation. When these +instincts, thus common to all individuals composing the hive, had been +highly perfected, it became of advantage in the struggle for existence +(between different hives or communities) that the functions of +reproduction should devolve more upon some individuals, while those of +co-operation should devolve more upon others. Consequently, this +division of labour began, and gradually became complete, as we now find +it in bees and ants. Perrier sustains the hypothesis thus briefly +sketched by pointing to certain species of social hymenoptera where we +may actually observe different stages of the process--from cases where +all the females of the hive are at the same time workers and breeders, +up to the cases where the severance between these functions has become +complete. Therefore, it seems to me, it is no longer necessary to +suppose that in these latter cases all the instincts of the (now) barren +females can only have been due to the unaided influence of natural +selection. + +Nevertheless, although I think that Perrier has made good his position +thus far, that his hypothesis fails to account for some of the instincts +which are manifested by neuter insects, such as those which, so far as I +can see, must necessarily be supposed to have originated after the +breeding and working functions had become separated--seeing that they +appear to have exclusive reference to this peculiar state of matters. +Possibly, however, Perrier might be able to meet each of these +particular instincts, by showing how they could have arisen out of +simpler beginnings, prior to the separation of the two functions in +question. There is no space to consider such possibilities in detail; +but, until this shall have been done, I do not think we are entitled to +conclude that the phenomena of instinct as presented by neuter insects +are demonstrably incompatible with the doctrines of Lamarck--or, that +these phenomena are available as a logical proof of the unassisted +agency of natural selection in the case of instincts in general[54]. + + [54] [See H. Spencer, _The Inadequacy of Natural Selection, A + Rejoinder to Professor Weismann_, Contemp. Rev. 1893; and + _Weismannism once more_, Ibid. Oct. 1894; Weismann, _The + All-sufficiency of Natural Selection_, Ibid. 1893; and _The + Effect of External Influences upon Development_, "Romanes + Lecture" 1894: also _Neuter Insects and Lamarckism_, W. Platt + Ball, Natural Science, Feb. 1894, and _Neuter Insects and + Darwinism_, J. T. Cunningham, Ibid. April 1894. C. Ll. M.] + + +(B.) +_Inherited Effects of Use and of Disuse._ + +There is no doubt that Darwin everywhere attaches great weight to this +line of evidence. Nevertheless, in my opinion, there is equally little +doubt that, taken by itself, it is of immeasurably less weight than +Darwin supposed. Indeed, I quite agree with Weismann that the whole of +this line of evidence is practically worthless; and for the following +reasons. + +The evidence on which Darwin relied to prove the inherited effects of +use and disuse was derived from his careful measurements of the increase +or decrease which certain bones of our domesticated animals have +undergone, as compared with the corresponding bones of ancestral stocks +in a state of nature. He chose domesticated animals for these +investigations, because, while yielding unquestionable cases of +increased or diminished use of certain organs over a large number of +sequent generations, the results were not complicated by the possible +interference of natural selection on the one hand, or by that of the +economy of nutrition on the other. For "with highly-fed domesticated +animals there seems to be no economy of growth, or any tendency to the +elimination of superfluous details[55];" seeing that, among other +considerations pointing in the same direction, "structures which are +rudimentary in the parent species, sometimes become partially +re-developed in our domesticated productions[56]." + + [55] _Variation of Plants and Animals_, vol. ii. p. 289. + + [56] _Ibid._ p. 346. + +The method of Darwin's researches in this connexion was as follows. +Taking, for example, the case of ducks, he carefully weighed and +measured the wing-bones and leg-bones of wild and tame ducks; and he +found that the wing-bones were smaller, while the leg-bones were larger, +in the tame than in the wild specimens. These facts he attributed to +many generations of tame ducks using their wings less, and their legs +more, than was the case with their wild ancestry. Similarly he compared +the leg-bones of wild rabbits with those of tame ones, and so forth--in +all cases finding that where domestication had led to increased use of a +part, that part was larger than in the wild parent stock; while the +reverse was the case with parts less used. Now, although at first sight +these facts certainly do seem to yield good evidence of the inherited +effects of use and disuse, they are really open to the following very +weighty objections. + +First of all, there is no means of knowing how far the observed effects +may have been due to increased or diminished use during only the +individual life-time of each domesticated animal. Again, and this is a +more important point, in all Darwin's investigations the increase or +decrease of a part was estimated, not by directly comparing, say the +wing-bones of a domesticated duck with the wing-bones of a wild duck, +but by comparing the _ratio_ between the wing and leg bones of a tame +duck with the _ratio_ between the wing and leg bones of a wild duck. +Consequently, if there be any reason to doubt the supposition that a +really inherited decrease in the size of a part thus estimated is due to +the inherited effects of disuse, such a doubt will also extend to the +evidence of increased size being due to the inherited effects of use. +Now there is the gravest possible doubt lying against the supposition +that any really inherited decrease in the size of a part is due to the +inherited effects of disuse. For it may be--and, at any rate to some +extent, must be--due to another principle, which it is strange that +Darwin should have overlooked. This is the principle which Weismann has +called Panmixia, and which cannot be better expressed than in his own +words:-- + + "A goose or a duck must possess strong powers of flight in the + natural state, but such powers are no longer necessary for + obtaining food when it is brought into the poultry-yard; so that a + rigid selection of individuals with well-developed wings at once + ceases among its descendants. Hence, in the course of generations, + a deterioration of the organs of flight must necessarily + ensue[57]." + + [57] _Essays_, i. p. 90. + +Or, to state the case in another way: if any structure which was +originally built up by natural selection on account of its use, ceases +any longer to be of so much use, in whatever degree it ceases to be of +use, in that degree will the premium before set upon it by natural +selection be withdrawn. And the consequence of this withdrawal of +selection as regards that particular part will be to allow the part to +degenerate in successive generations. Such is the principle which +Weismann calls Panmixia, because, by the withdrawal of selection from +any particular part, promiscuous breeding ensues with regard to that +part. And it is easy to see that this principle must be one of very +great importance in nature; because it must necessarily come into +operation in all cases where any structure or any instinct has, through +any change in the environment or in the habits of a species, ceased to +be useful. It is likewise easy to see that its effect must be the same +as that which was attributed by Darwin to the inherited effect of +disuse; and, therefore, that the evidence on which he relied in proof of +the inherited effects both of use and of disuse is vitiated by the fact +that the idea of Panmixia did not occur to him. + +Here, however, it may be said that the idea first occurred to me[58] +just after the publication of the last edition of the _Origin of +Species_. I called the principle the Cessation of Selection--which I +still think a better, because a more descriptive, term than Panmixia; +and at that time it appeared to me, as it now appears to Weismann, +entirely to supersede the necessity of supposing that the effect of +disuse is ever inherited in any degree at all. Thus it raised the whole +question as to the admissibility of Lamarckian principles in general; or +the question on which we are now engaged touching the possible +inheritance of acquired, as distinguished from congenital, characters. +But on discussing the matter with Mr. Darwin, he satisfied me that the +larger question was not to be so easily closed. That is to say, although +he fully accepted the principle of the Cessation of Selection, and as +fully acknowledged its obvious importance, he convinced me that there +was independent evidence for the transmission of acquired characters, +sufficient in amount to leave the general structure of his previous +theory unaffected by what he nevertheless recognized as a factor which +must necessarily be added. All this I now mention in order to show that +the issue which Weismann has raised since Darwin's death was expressly +contemplated during the later years of Darwin's life. For if the idea of +Panmixia--in the absence of which Weismann's entire system would be +impossible--had never been present to Darwin's mind, we should have been +left in uncertainty how he would have regarded this subsequent revolt +against what are generally called the Lamarckian principles[59]. + + [58] _Nature_, vol. ix. pp. 361-2, 440-1; and vol. x. p. 164. + + [59] Appendix I. + +Moreover, in this connexion we must take particular notice that the +year after I had published these articles on the Cessation of Selection, +and discussed with Mr. Darwin the bearing of this principle on the +question of the transmission of acquired characters, Mr. Galton followed +with his highly important essay on Heredity. For in this essay Mr. +Galton fully adopted the principle of the Cessation of Selection, and +was in consequence the first publicly to challenge the Lamarckian +principles--pointing out that, if it were thus possible to deny the +transmission of acquired characters _in toto_, "we should be relieved +from all further trouble"; but that, if such characters are transmitted +"in however faint a degree, a complete theory of heredity must account +for them." Thus the question which, in its revived condition, is now +attracting so much attention, was propounded in all its parts some +fifteen or sixteen years ago; and no additional facts or new +considerations of any great importance bearing upon the subject have +been adduced since that time. In other words, about a year after my own +conversations with Mr. Darwin, the whole matter was still more +effectively brought before his notice by his own cousin. And the result +was that he still retained his belief in the Lamarckian factors of +organic evolution, even more strongly than it was retained either by Mr. +Galton or myself[60]. + + [60] For a fuller statement of Mr. Galton's theory of Heredity, and + its relation to Weismann's, see _An Examination of + Weismannism_. + +We have now considered the line of evidence on which Darwin chiefly +relied in proof of the transmissibility of acquired characters; and it +must be allowed that this line of evidence is practically worthless. +What he regarded as the inherited effects of use and of disuse may be +entirely due to the cessation of selection in the case of our +domesticated animals, combined with an active _reversal_ of selection in +the case of natural species. And in accordance with this view is the +fact that the degeneration of disused parts proceeds much further in the +case of wild species than it does in that of domesticated varieties. For +although it may be said that in the case of wild species more time has +been allowed for a greater accumulation of the inherited effects of +disuse than can have been the case with domesticated varieties, the +alternative explanation is at least as probable--that in the case of +wild species the merely negative, or passive, influence of the +_cessation_ of selection has been continuously and powerfully assisted +by the positive, or active, influence of the _reversal_ of selection, +through economy of growth and the general advantage to be derived from +the abolition of useless parts[61]. + + [61] For a fuller explanation of the important difference between + the mere cessation and the actual reversal of selection, see + Appendix I. + +The absence of any good evidence of this direct kind in favour of +use-inheritance will be rendered strikingly apparent to any one who +reads a learned and interesting work by Professor Semper[62]. His object +was to show the large part which he believed to have been played by +external conditions of life in directly modifying organic types--or, in +other words, of proving that side of Lamarckianism which refers to the +immediate action of the environment, whether with or without the +co-operation of use-inheritance and natural selection. Although Semper +gathered together a great array of facts, the more carefully one reads +his book the more apparent does it become that no single one of the +facts is in itself conclusive evidence of the transmission to progeny of +characters which are acquired through use-inheritance or through direct +action of the environment. Every one of the facts is susceptible of +explanation on the hypothesis that the principle of natural selection +has been the only principle concerned. This, however, it must be +observed, is by no means equivalent to proving that characters thus +acquired are not transmitted. As already pointed out, it is +impracticable with species in a state of nature to dissociate the +distinctively Darwinian from the possibly Lamarckian factors; so that +even if the latter are largely operative, we can only hope for direct +evidence of the fact from direct experiments on varieties in a state of +domestication. To this branch of our subject, therefore, we will now +proceed. + + [62] _Animal Life_, International Scientific Series, vol. xxxi. + + + + +CHAPTER IV. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(C.) +_Experimental Evidence in favour of the Inheritance of Acquired +Characters._ + + +Notwithstanding the fact already noticed, that no experiments have +hitherto been published with reference to the question of the +transmission of acquired characters[63], there are several researches +which, with other objects in view, have incidentally yielded seemingly +good evidence of such transmission. The best-known of these +researches--and therefore the one with which I shall begin--is that of +Brown-Séquard touching the effects of certain injuries of the nervous +system in guinea-pigs. + + [63] The experiments of Galton and Weismann upon this subject are + nugatory, as will be shown later on. But since the above was + written an important research has been published by Mr. + Cunningham, of the Marine Biological Association. For a full + account I must refer the reader to his forthcoming paper in the + _Philosophical Transactions_. The following is his own + statement of the principal results:-- + + "A case which I have myself recently investigated + experimentally seems to me to support very strongly the theory + of the inheritance of acquired characters, I have shown that in + normal flat-fishes, if the lower side be artificially exposed + to light for a long time, pigmentation is developed on that + side; but when the exposure is commenced while the specimens + are still in process of metamorphosis, when pigment-cells are + still present on the lower side, the action of light does not + prevent the disappearance of these pigment-cells. They + disappear as in individuals living under normal conditions, but + after prolonged exposure pigment-cells reappear. The first fact + proves that the disappearance of the pigment-cells from the + lower side in the metamorphosis is an hereditary character, and + not a change produced in each individual by the withdrawal of + the lower side from the action of light. On the other hand, the + experiments show that the absence of pigment-cells from the + lower side throughout life is due to the fact that light does + not act upon that side, for, when it is allowed to act, + pigment-cells appear. It seems to me the only reasonable + conclusion from these facts is, that the disappearance of + pigment-cells was originally due to the absence of light, and + that this change has now become hereditary. The pigment-cells + produced by the action of light on the lower side are in all + respects similar to those normally present on the upper side of + the fish. If the disappearance of the pigment-cells were due + entirely to a variation of the germ-plasm, no external + influence could cause them to reappear, and, on the other hand, + if there were no hereditary tendency, the colouration of the + lower side of the flat-fish when exposed would be rapid and + complete."--_Natural Science_, Oct. 1893. + +During a period of thirty years Brown-Séquard bred many thousands of +guinea-pigs as material for his various researches; and in those whose +parents had not been operated upon in the ways to be immediately +mentioned, he never saw any of the peculiarities which are about to be +described. Therefore the hypothesis of coincidence, at all events, must +be excluded. The following is his own summary of the results with which +we are concerned:-- + + 1st. Appearance of epilepsy in animals born of parents which had + been rendered epileptic by an injury to the spinal cord. + + 2nd. Appearance of epilepsy also in animals born of parents which + had been rendered epileptic by section of the sciatic nerve. + + 3rd. A change in the shape of the ear in animals born of parents in + which such a change was the effect of a division of the cervical + sympathetic nerve. + + 4th. Partial closure of the eyelids in animals born of parents in + which that state of the eyelids had been caused either by section + of the cervical sympathetic nerve, or the removal of the superior + cervical ganglion. + + 5th. Exophthalmia in animals born of parents in which an injury to + the restiform body had produced that protrusion of the eyeball. + This interesting fact I have witnessed a good many times, and seen + the transmission of the morbid state of the eye continue through + four generations. In these animals, modified by heredity, the two + eyes generally protruded, although in the parents usually only one + showed exophthalmia, the lesion having been made in most cases only + on one of the corpora restiformia. + + 6th. Haematoma and dry gangrene of the ears in animals born of + parents in which these ear-alterations had been caused by an injury + to the restiform body near the nib of the calamus. + + 7th. Absence of two toes out of the three of the hind leg, and + sometimes of the three, in animals whose parents had eaten up their + hind-leg toes which had become anaesthetic from a section of the + sciatic nerve alone, or of that nerve and also of the crural. + Sometimes, instead of complete absence of the toes, only a part of + one or two or three was missing in the young, although in the + parent not only the toes but the whole foot were absent (partly + eaten off, partly destroyed by inflammation, ulceration, or + gangrene.) + + 8th. Appearance of various morbid states of the skin and hair of + the neck and face in animals born of parents having had similar + alterations in the same parts, as effects of an injury to the + sciatic nerve. + +These results[64] have been independently vouched for by two of +Brown-Séquard's former assistants--Dr. Dupuy, and the late Professor +Westphal. Moreover, his results with regard to epilepsy have been +corroborated also by Obersteiner[65]. I may observe, in passing, that +this labour of testing Brown-Séquard's statements is one which, in my +opinion, ought rather to have been undertaken, if not by Weismann +himself, at all events by some of his followers. Both he and they are +incessant in their demand for evidence of the transmission of acquired +characters; yet they have virtually ignored the foregoing very +remarkable statements. However, be this as it may, all that we have now +to do is to consider what the school of Weismann has had to say with +regard to these experiments on the grounds of general reasoning which +they have thus far been satisfied to occupy. + + [64] For Professor Weismann's statement of and discussion of these + results see _Essays_, vol. i. p. 313. + + [65] _Oesterreichische medicinische Jahrbücher_, 1875, 179. + +In view of Obersteiner's corroboration of Brown-Séquard's results +touching the artificial production and subsequent transmission of +epilepsy, Weismann accepts the facts, but, in order to save his theory +of heredity, he argues that the transmission may be due to a traumatic +introduction of "some unknown microbe" which causes the epilepsy in the +parent, and, by invading the ova or spermatozoa as the case may be, also +produces epilepsy in the offspring. Here, of course, there would be +transmission of epilepsy, but it would not be, technically speaking, an +hereditary transmission. The case would resemble that of syphilis, where +the sexual elements remain unaffected as to their congenital endowments, +although they have been made the vehicles for conveying an organic +poison to the next generation. + +Now it would seem that this suggestion is not, on the face of it, a +probable one. For "some unknown microbe" it indeed must be, which is +always on hand to enter a guinea-pig when certain operations are being +performed on certain parts of the nervous system, but yet will never +enter when operations of any kind are being effected elsewhere. +Moreover, Westphal has produced the epilepsy _without any incision_, by +striking the heads of the animals with a hammer[66]. This latter fact, +it appears to me, entirely abolishes the intrinsically improbable +suggestion touching an unknown--and strangely eclectic--microbe. +However, it is but fair to state what Weismann himself has made of this +fact. The following is what he says:-- + + [66] _Loc. cit._ + + "It is obvious that the presence of microbes can have nothing to do + with such an attack, but the shock alone must have caused + morphological and functional changes in the centre of the pons and + medulla oblongata, identical with those produced by microbes in the + other cases.... Various stimuli might cause the nervous centres + concerned to develop the convulsive attack which, together with its + after-effects, we call epilepsy. In Westphal's case, such a + stimulus would be given by a powerful mechanical shock (viz. blows + on the head with a hammer); in Brown-Séquard's experiments, by the + penetration of microbes[67]." + + [67] _Essays_, vol. i. p. 315. + +But from this passage it would seem that Weismann has failed to notice +that in "Westphal's case," as in "Brown-Séquard's experiments," the +epilepsy was _transmitted to progeny_. That epilepsy may be produced in +guinea-pigs by a method which does not involve any cutting (i.e. +possibility of inoculation) would no doubt tend to corroborate the +suggestion of microbes being concerned in its transmission when it is +produced by cutting, _if in the former case there were no such +transmission_. But as there _is_ transmission in _both_ cases, the +facts, so far as I can see, entirely abolish the suggestion. For they +prove that even when epilepsy is produced in the parents under +circumstances which render "it obvious that the presence of microbes can +have nothing to do with such an attack," the epileptiform condition is +notwithstanding transmitted to the progeny. What, then, is gained by +retaining the intrinsically improbable hypothesis of microbes to explain +the fact of transmission "in Brown-Séquard's experiments," when this +very same fact is proved to occur without the possibility of microbes +"in Westphal's case"? + +The only other objection with regard to the seeming transmission of +traumatic epilepsy which Weismann has advanced is, that such epilepsy +may be produced by two or three very different operations--viz. division +of the sciatic nerves (one or both), an injury to the spinal cord, and a +stroke on the head. Does not this show, it is asked, that the epileptic +condition of guinea-pigs is due to a generally unstable condition of the +whole nervous system and is not associated with any particular part +thereof? Well, supposing that such is the case, what would it amount to? +I cannot see that it would in any way affect the only question in +debate--viz. What is the significance of the fact that epilepsy is +_transmitted_? Even if it be but "a tendency," "a disposition," or "a +diathesis" that is transmitted, it is none the less a case of +transmission, in fact quite as much so as if the pathological state were +dependent on the impaired condition of any particular nerve-centre. For, +it must be observed, there can be no question that it is always produced +by an operation of _some_ kind. If it were ever to originate in +guinea-pigs spontaneously, there might be some room for supposing that +its transmission is due to a congenital tendency running through the +whole species--although even then it would remain unaccountable, on the +ultra-Darwinian view, why this tendency should be congenitally +_increased_ by means of an operation. But epilepsy does not originate +spontaneously in guinea-pigs; and therefore the criticism in question +appears to me irrelevant. + +Again, it may be worth while to remark that Brown-Séquard's experiments +do not disprove the possibility of its being some one nerve-centre which +is concerned in all cases of traumatic epilepsy. And this possibility +becomes, I think, a probability in view of Luciani's recent experiments +on the dog. These show that the epileptic condition can be produced in +this animal by injury to the cortical substance of the hemispheres, and +is then transmitted to progeny[68]. These experiments, therefore, are of +great interest--first, as showing that traumatic and transmissible +epilepsy is not confined to guinea-pigs; and next, as indicating that +the pathological state in question is associated with the highest +nerve-centres, which may therefore well be affected by injury to the +lower centres, or even by section of a large nerve trunk. + + [68] _Les fonctions du Cerveau_, p. 102. + +So much, then, with regard to the case of transmitted epilepsy. But now +it must be noted that, even if Weismann's suggestion touching microbes +were fully adequate to meet this case, it would still leave unaffected +those of transmitted protrusion of the eye, drooping of the eyelid, +gangrene of the ear, absence of toes, &c. In all these cases the facts, +as stated by Brown-Séquard, are plainly unamenable to any explanation +which would suppose them due to microbes, or even to any general +neurotic condition induced by the operation. They are much too definite, +peculiar, and localized. Doubtless it is on this account that the school +of Weismann has not seriously attempted to deal with them, but merely +recommends their repetition by other physiologists[69]. Certain +criticisms, however, have been urged by Weismann against the +_interpretation_ of Brown-Séquard's facts as evidence in favour of the +transmission of acquired characters. It does not appear to me that these +criticisms present much weight; but it is only fair that we should here +briefly consider them[70]. + + [69] _Essays_, vol. i. p. 82. + + [70] As Weismann gives an excellent abstract of all the alleged + facts up to date (_Essays_, vol. i. pp. 319-324), it is + needless for me to supply another, further than that which I + have already made from Brown-Séquard. + +First, with regard to Brown-Séquard's results other than the production +of transmitted epilepsy, Weismann allows that the hypothesis of microbes +can scarcely apply. In order to meet these results, therefore, he +furnishes another suggestion--viz. that where the nervous system has +sustained "a great shock," the animals are very likely to bear "weak +descendants, and such as are readily affected by disease." Then, in +answer to the obvious consideration, "that this does not explain why the +offspring should suffer from the same disease" as that which has been +produced in the parents, he adds--"But this does not appear to have been +by any means invariably the case. For 'Brown-Séquard himself says, the +changes in the eye of the offspring were of a very variable nature, and +were only occasionally exactly similar to those observed in the +parents.'" + +Now, this does not appear to me a good commentary. In the first place, +it does not apply to the other cases (such as the ears and the toes), +where the changes in the offspring, when they occurred at all, _were_ +exactly similar to those observed in the parents, save that some of them +occasionally occurred on the _opposite_ side, and frequently also on +_both_ sides of the offspring. These subordinate facts, however, will +not be regarded by any physiologist as making against the more ready +interpretation of the results as due to heredity. For a physiologist +well knows that homologous parts are apt to exhibit correlated +variability--and this especially where variations of a congenital kind +are concerned, and also where there is any reason to suppose that the +nervous system is involved. Moreover, even in the case of the eye, it +was always protrusion that was caused in the parent and transmitted to +the offspring as a result of injuring the restiform bodies of the +former; while it was always partial closure of the eyelids that was +caused and transmitted by section of the sympathetic nerve, or removal +of the cervical ganglia. Therefore, if we call such effects "diseases," +surely it _was_ "the same disease" which in each case appeared in the +parents and reappeared in their offspring. Again, the "diseases" were so +peculiar, definite, and localized, that I cannot see how they can be +reasonably ascribed to a general nervous "shock." Why, for instance, if +this were the case, should a protruding eye never result from removal +of the cervical ganglia, a drooping eyelid from a puncture of the +restiform body, a toeless foot from either or both of these operations, +and so on? In view of such considerations I cannot deem these +suggestions touching "microbes" and "diseases" as worthy of the +distinguished biologist from whom they emanate. + +Secondly, Weismann asks--How can we suppose these results to be +instances of the transmission of acquired characters, when from +Brown-Séquard's own statement of them it appears that the mutilation +itself was not inherited, but only its effects? Neither in the case of +the sciatic nerve, the sympathetic nerve, the cervical ganglion, nor the +restiform bodies, was there ever any trace of transmitted injury in the +corresponding parts of the offspring; so that, if the "diseases" from +which they suffered be regarded as hereditary, we have to suppose that a +consequence was in each case transmitted without the transmission of its +cause, which is absurd. But I do not think that this criticism can be +deemed of much weight by a physiologist as distinguished from a +naturalist. For nothing is more certain to a student of physiology, in +any of its branches, than that negative evidence, if yielded by the +microscope alone, is most precarious. Therefore it does not need a +_visible_ change in the nervous system to be present, in order that the +part affected should be functionally weak or incapable: pathology can +show numberless cases of nerve-disorder the "structural" causes of which +neither the scalpel nor the microscope can detect. So that, if any +peculiar form of nerve-disorder is transmitted to progeny, and if it be +certain that it has been caused by injury to some particular part of +the nervous system, I cannot see that there is any reason to doubt the +transmission of a nervous lesion merely on the ground that it is not +visibly discernible. Of course there may be other grounds for doubting +it; but I am satisfied that this ground is untenable. Besides, it must +be remembered, as regards the particular cases in question, that no one +has thus far investigated the histology of the matter by the greatly +improved methods which are now at our disposal. + + * * * * * + +I have now considered all the criticisms which have been advanced +against what may be called the Lamarckian interpretation of +Brown-Séquard's results; and I think it will be seen that they present +very little force--even if it can be seen that they present any force at +all. But it must be remembered that this is a different thing from +saying that the Lamarckian interpretation is the true one. The facts +alleged are, without question, highly peculiar; and, on this account +alone, Brown-Séquard's interpretation of them ought to be deemed +provisional. Hence, although as yet they have not encountered any valid +criticism from the side of ultra-Darwinian theory, I do not agree with +Darwin that, on the supposition of their truth as facts, they furnish +positive proof of the transmission of acquired characters. Rather do I +agree with Weismann that further investigation is needed in order to +establish such an important conclusion on the basis of so unusual a +class of facts. This further investigation, therefore, I have +undertaken, and will now state the results. + +Although this work was begun over twenty years ago, and then yielded +negative results, it was only within the last decade that I resumed it +more systematically, and under the tutelage of Brown-Séquard himself. +During the last two years, however, the experiments have been so much +interrupted by illness that even now the research is far from complete. +Therefore I will here confine myself to a tabular statement of the +results as far as they have hitherto gone, on the understanding that, in +so far as they are negative or doubtful, I am not yet prepared to +announce them as final. + +We may take Brown-Séquard's propositions in his own order, as already +given on page 104. + + 1st. Appearance of epilepsy in animals born of parents which had + been rendered epileptic by an injury to the spinal cord. + + 2nd. Appearance of epilepsy also in animals born of parents which + had been rendered epileptic by section of the sciatic nerve. + +I did not repeat these experiments with a view to producing epilepsy, +because, as above stated, they had been already and sufficiently +corroborated in this respect. But I repeated many times the experiments +of dividing the sciatic nerve for the purpose of testing the statements +made later on in paragraphs 7 and 8, and observed that it almost always +had the effect of producing epilepsy in the animal thus operated +upon--and this of a peculiar kind, the chief characteristics of which +may here be summarized. The epileptiform habit does not supervene until +some considerable time after the operation; it is then transitory, +lasting only for some weeks or months. While the habit endures the fits +never occur spontaneously, but only as a result of irritating a small +area of skin behind the ear on the same side of the body as that on +which the sciatic nerve had been divided. Effectual irritation may be +either mechanical (such as gentle pinching), electrical, or, though less +certainly, thermal. The area of skin in question, soon after the +epileptiform habit supervenes, and during all the time that it lasts, +swarms with lice of the kind which infest guinea-pigs--i.e. the lice +congregate in this area, on account, I think, of the animal being there +insensitive, and therefore not disturbing its parasites in that +particular spot; otherwise it would presumably throw itself into fits by +scratching that spot. On removing the skin from the area in question, no +kind or degree of irritation supplied to the subjacent tissue has any +effect in producing a fit. A fit never lasts for more than a very few +minutes, during which the animal is unconscious and convulsed, though +not with any great violence. The epileptiform habit is but rarely +transmitted to progeny. Most of these observations are in accordance +with those previously made by Brown-Séquard, and also by others who have +repeated his experiments under this heading. I can have no doubt that +the injury of the sciatic nerve or spinal cord produces a change in some +of the cerebral centres, and that it is this change--whatever it is and +in whatever part of the brain it takes place--which causes the +remarkable phenomena in question. + + 3rd. A change in the shape of the ear in animals born of parents in + which such a change was the effect of a division of the cervical + sympathetic nerve. + + 4th. Partial closure of the eyelids in animals born of parents in + which that state of the eyelids had been caused either by section + of the cervical sympathetic nerve, or the removal of the superior + cervical ganglion. + +I have not succeeded in corroborating these results. It must be added, +however, that up to the time of going to press my experiments on this, +the easiest branch of the research, have been too few fairly to prove a +negative. + + 5th. Exophthalmia in animals born of parents in which an injury to + the restiform body had produced that protrusion of the eyeball.... + In these animals, modified by heredity, the two eyes generally + protruded, although in the parents usually only one showed + exophthalmia, the lesion having been made in most cases only on one + of the corpora restiformia. + +I have fully corroborated the statement that injury to a particular spot +of the restiform body is quickly followed by a marked protrusion of the +eyeball on the same side. I have also had many cases in which some of +the progeny of parents thus affected have shown considerable protrusion +of the eyeballs on both sides, and this seemingly abnormal protrusion +has been occasionally transmitted to the next generation. Nevertheless, +I am far from satisfied that this latter fact is anything more than an +accidental coincidence. For I have never seen the so-called exophthalmia +of progeny exhibited in so high a degree as it occurs in the parents as +an immediate result of the operation, while, on examining any large +stock of normal guinea-pigs, there is found a considerable amount of +individual variation in regard to prominence of eyeballs. Therefore, +while not denying that the obviously abnormal amount of protrusion due +to the operation may be inherited in lesser degrees, and thus may be the +cause of the unusual degree of prominence which is sometimes seen in the +eyeballs of progeny born of exophthalmic parents, I am unable to affirm +so important a conclusion on the basis supplied by these experiments. + + 6th. Haematoma and dry gangrene of the ears in animals born of + parents in which these ear-alterations had been caused by an injury + to the restiform body. + +As regards the animals operated upon (i. e. the parents), I find that +the haematoma and dry gangrene may supervene either several weeks after +the operation, or at any subsequent time up to many months. When it does +supervene it usually affects the upper parts of both ears, and may then +eat its way down until, in extreme cases, it has entirely consumed +two-thirds of the tissue of both ears. As regards the progeny of animals +thus affected, in some cases, but by no means in all, a similarly morbid +state of the ears may arise apparently at any time in the life-history +of the individual. But I have observed that in cases where two or more +individuals _of the same litter_ develop this diseased condition, they +usually do so at about the same time--even though this be many months +after birth, and therefore after the animals are fully grown. But in +progeny the morbid process never goes so far as in the parents which +have been operated upon, and it almost always affects the _middle_ +thirds of the ears. In order to illustrate these points, reproductions +of two of my photographs are appended. They represent the consequences +of the operation on a male and a female guinea-pig. Among the progeny of +both these animals there were several in which a portion of each ear was +consumed by apparently the same process, where, of course, there had +been no operation. + +[Illustration: FIG. 1.--Reproduction of photographs from life of a male +and female guinea-pig, whose left restiform bodies had been injured by a +scalpel six months previously. The loss of tissue in both ears was due +to haematoma and dry gangrene, which, however, had ceased when the +photograph was taken.] + +It should be observed that not only is a different _part_ of the ear +affected in the progeny, but also a very much less _quantity_ thereof. +Naturally, therefore, the hypothesis of heredity seems less probable +than that of mere coincidence on the one hand, or of transmitted +microbes on the other. But I hope to have fairly excluded both these +alternative explanations. For, as regards merely accidental coincidence, +I have never seen this very peculiar morbid process in the ears, or in +any other parts, of guinea-pigs which have neither themselves had their +restiform bodies injured, nor been born of parents thus mutilated. As +regards the hypothesis of microbes, I have tried to inoculate the +corresponding parts of the ears of normal guinea-pigs, by first +scarifying those parts and then rubbing them with the diseased surfaces +of the ears of mutilated guinea-pigs; but have not been able in this way +to communicate the disease. + +It will be seen that the above results in large measure corroborate the +statements of Brown-Séquard; and it is only fair to add that he told me +they are the results which he had himself obtained most frequently, but +that he had also met with many cases where the diseased condition of the +ears in parents affected the same parts in their progeny, and also +occurred in more equal degrees. Lastly, I should like to remark, with +regard to these experiments on restiform bodies, and for the benefit of +any one else who may hereafter repeat them, that it will be necessary +for him to obtain precise information touching the _modus operandi_. For +it is only one very localized spot in each restiform body which has to +be injured in order to produce any of the results in question. I myself +lost two years of work on account of not knowing this exact spot before +going to Paris for the purpose of seeing Brown-Séquard himself perform +the operation. I had in the preceding year seen one of his assistants do +so, but this gentleman had a much more careless method, and one which in +my hands yielded uniformly negative results. The exact spot in question +in the restiform body is as far forwards as it is possible to reach, and +as far down in depth as is compatible with not producing rotatory +movements. + + 7th. Absence of two toes out of the three of the hind leg, and + sometimes of the three, in animals whose parents had eaten up their + hind-leg toes which had become anaesthetic from a section of the + sciatic nerve alone, or of that nerve and also of the crural. + Sometimes, instead of complete absence of the toes, only a part of + one or two or three was missing in the young, although in the + parent not only the toes but the whole foot were absent. + +As I found that the results here described were usually given by +division of the sciatic nerve alone--or, more correctly, by excision of +a considerable portion of the nerve, in order to prevent regeneration--I +did not also divide the crural. But, although I have bred numerous +litters from parents thus injured, there has been no case of any +inherited deficiency of toes. My experiments in this connexion were +carried on through a series of six successive generations, so as to +produce, if possible, a cumulative effect. Nevertheless, no effect of +any kind was produced. On the other hand, Brown-Séquard informed me that +he had observed this inherited absence of toes only in about one or two +per cent. of cases. Hence it is possible enough, that my experiments +have not been sufficiently numerous to furnish a case. It may be added +that there is here no measurable possibility of accidental coincidence +(seeing that normal guinea-pigs do not seem ever to produce young with +any deficiency of toes), while the only possibility of mal-observation +consists in some error with regard to the isolation (or the tabulation) +of parents and progeny. Such an error, however, may easily arise. For +gangrene of the toes does not set in till some considerable time after +division of the sciatic nerve. Hence, if the wound be healed before the +gangrene begins, and if any mistake has been made with regard to the +isolation (or tabulation) of the animal, it becomes possible that the +latter should be recorded as an uninjured, instead of an injured, +individual. On this account one would like to be assured that +Brown-Séquard took the precaution of examining the state of the sciatic +nerve in those comparatively few specimens which he alleges to have +displayed such exceedingly definite proof of the inheritance of a +mutilation. For it is needless to remark, after what has been said in +the preceding chapter on the analogous case of epilepsy, that the proof +would not be regarded by any physiologist as displaced by the fact that +there is no observable deficiency in the sciatic nerve of the toeless +young. + + 8th. Appearance of various morbid states of the skin and hair of + the neck and face in animals born of parents having had similar + alterations in the same parts, as effects of an injury to the + sciatic nerve. + +I have not paid any attention to this paragraph, because the facts which +it alleges did not seem of a sufficiently definite character to serve as +a guide to further experiment. + +On the whole, then, as regards Brown-Séquard's experiments, it will be +seen that I have not been able to furnish any approach to a full +corroboration. But I must repeat that my own experiments have not as yet +been sufficiently numerous to justify me in repudiating those of his +statements which I have not been able to verify. + +The only other experimental results, where animals are concerned, which +seemed to tell on the side of Lamarckianism, are those of Mr. +Cunningham, already alluded to. But, as the research is still in +progress, the school of Weismann may fairly say that it would be +premature to discuss its theoretical bearings. + + * * * * * + +Passing now from experiments on animals to experiments on plants, I must +again ask it to be borne in mind, that here also no researches have been +published, which have had for their object the testing of the question +on which we are engaged. As in the case of animals, therefore, so in +that of plants, we are dependent for any experimental results bearing +upon the subject to such as have been gained incidentally during the +course of investigations in quite other directions. + +Allusion has already been made, in my previous essay, to De Vries' +observations on the chromatophores of algae passing from the ovum of the +mother to the daughter organism; and we have seen that even Weismann +admits, "It appears possible that a transmission of somatogenetic +variation has here occurred[71]." It will now be my object to show that +such variations appear to be sometimes transmitted in the case of +higher plants, and this under circumstances which carry much less +equivocal evidence of the inheritance of acquired characters, than can +be rendered by the much more simple organization of an alga. + + [71] _Examination of Weismannism_, p. 83. + +I have previously mentioned Hoffmann's experiments on transplantation, +the result of which was to show that variations, directly induced by +changed conditions of life, were reproduced by seed[72]. Weismann, +however, as we have seen, questions the _somatogenetic_ origin of these +variations--attributing the facts to a _blastogenetic_ change produced +in the plants by a direct action of the changed conditions upon the +germ-plasm itself[73]. And he points out that whether he is right or +wrong in this interpretation can only be settled by ascertaining whether +the observable somatic changes occur in the generation which is first +exposed to the changed conditions of life. If they do occur in the first +generation, they are somatogenetic changes, which afterwards react on +the substance of heredity, so as to transmit the acquired peculiarities +to progeny. But if they do not occur till the second (or any later) +generation, they are presumably blastogenetic. Unfortunately Hoffmann +does not appear to have attended to this point with sufficient care, but +there are other experiments of the same kind where the point has been +specially observed. + + [72] _Examination of Wiesmannism_, p. 93. + + [73] _Ibid._ p. 153. + +For instance, M. L. A. Carrière[74] gathered seed from the wild radish +(_Raphanus Raphanistrum_) in France, and sowed one lot in the light dry +soil near the Museum of Natural History in Paris, while another lot was +sown by him at the same time in heavy soil elsewhere. His object was to +ascertain whether he could produce a good cultivated radish by +methodical selection; and this he did; in a wonderfully rapid manner, +during the course of a very few generations. But the point for us is, +that _from the first_ the plants grown in the light soil of Paris +presented sundry marked differences from those grown in the heavy soil +of the country; and that these points of difference had nothing to do +with the variations on which his artificial selection was brought to +bear. For while his artificial selection was directed to increasing the +_size_ of the "root," the differences in question had reference to its +_form_ and _colour_. In Paris an elongated form prevailed, which +presented either a white or a rose colour: in the country the form was +more rounded, and the colour violet, dark brown, or "almost black." Now, +as these differences were strongly apparent in the first generation, and +were not afterwards made the subject of selection, both in origin and +development they must have been due to "climatic" influences acting on +the somatic tissues. And although the author does not appear to have +tested their hereditary characters by afterwards sowing the seed from +the Paris variety in the country, or _vice versa_, we may fairly +conclude that these changes must have been hereditary--1st, from the +fact of their intensification in the course of the five sequent +generations over which the experiment extended, and, 2nd, from the very +analogous results which were similarly obtained in the following case +with another genus, where both the somatogenetic and the hereditary +characters of the change were carefully and specially observed. This +case is as follows. + + [74] _Origine des Plantes Domestiques, démontrée par la culture du + Radis Sauvage_ (Paris, 1869). + +The late Professor James Buckman, F.R.S., saved some seed from wild +parsnips (_P. sativa_) in the summer of 1847, and sowed under changed +conditions of life in the spring of 1848. The plants grown from these +wild seeds were for the most part like wild plants; but some of them had +"already (i.e. in the autumn of 1848) the light green and smooth aspect +devoid of hairs which is peculiar to the cultivated plant; and among the +latter there were a few with longer leaves and broader divisions of +leaf-lobes than the rest--the leaves, too, all growing systematically +round one central bud. The roots of the plant when taken up were +observed to be for the most part more fleshy than those of wild +examples[75]." + + [75] _Journl. Agric. Soc._ 1848. + +Professor Buckman then proceeds to describe how he selected the best +samples for cultivation in succeeding generations, till eventually the +variety which he called "The Student" was produced, and which Messrs. +Sutton still regard as the best variety in their catalogue. That is to +say, it has come true to seed for the last forty years; and although +such great excellence and stability are doubtless in chief part due to +the subsequent process of selection by Professor Buckman in the years +1848-1850, this does not affect the point with which we are here +concerned--namely, that the somatogenetic changes of the plants in the +first generation were transmitted by seed to the second generation, and +thus furnished Professor Buckman with the material for his subsequent +process of selection. And the changes in question were not merely of a +very definite character, but also of what may be termed a very _local_ +character--affecting only particular tissues of the soma, and therefore +expressive of a high degree of _representation_ on the part of the +subsequently developed seed, by which they were faithfully reproduced in +the next generation. + +Here is another case. M. Lesage examined the tissues of a large number +of plants growing both near to, and remote from, the sea. He suspected +that the characteristic fleshiness, &c. of seaside plants was due to the +influence of sea-salt; and proved that such was the case by causing the +characters to occur in inland plants as a result of watering them with +salt-water. Then he adds:-- + + "J'ai réussi surtout pour le _Lepidium sativum_ cultivé en 1888; + j'ai obtenu pour la même plante des résultats plus nets encore dans + la culture de 1889, entreprise en semant les graines récoltées avec + soin des pots de l'année précédente et traitées exactement de la + même façon[76]." + + [76] _Rev. Gén. de Bot._ tom. ii. p. 64. + +Here, it will be observed, there was no selection; and therefore the +increased hereditary effect in the second generation must apparently be +ascribed to a continuance of influence exercised by somatic tissues on +germinal elements; for at the time when the changes were produced no +seed had been formed. In other words, the accumulated change, like the +initial change, would seem to have been exclusively of somatogenetic +origin; and yet it so influenced the qualities of the seed (as this was +afterwards formed), that the augmented changes were transmitted to the +next generation, part for part, as the lesser changes had occurred in +the preceding generation. "This experiment, therefore, like Professor +Buckman's, shows that the alteration of the tissues was carried on in +the second generation from the point gained in the first. In both cases +no germ-plasm (in the germ-cells) existed at the time during which the +alterations arose, as they were confined to the vegetative system; and +in the case of the parsnips and carrots, being biennials no germ-cells +are produced till the second year has arrived[77]." + + [77] I am indebted to the Rev. G. Henslow for the references to + these cases. This and the passages which follow are quoted from + his letters to me. + +Once more, Professor Bailey remarks:-- + + "Squashes often show remarkable differences when grown upon + different soils; and these differences can sometimes be perpetuated + for a time by seeds. The writer has produced, from the same parent, + squashes so dissimilar, through the simple agency of a change of + soil in one season, that they might readily be taken for distinct + varieties. Peas are known to vary in the same manner. The seeds of + a row of peas of the same kind, last year gave the writer marked + variations due to differences of soil.... Pea-growers characterize + soils as 'good' and 'viney.' Upon the latter sort the plants run to + vine at the expense of the fruit, and their offspring for two or + three generations have the same tendency[78]." + + [78] _Gardener's Chronicle_, May 31, 1890, p. 677. + +I think these several cases are enough to show that, while the +Weismannian assumption as to the seeming transmission of somatogenetic +characters being restricted to the lowest kinds of plants is purely +gratuitous, there is no small amount of evidence to the contrary--or +evidence which seems to prove that a similar transmission occurs +likewise in the higher plants. And no doubt many additional cases might +be advanced by any one who is well read in the literature of economic +botany. + +It appears to me that the only answer to such cases would be furnished +by supposing that the hereditary changes are due to an alteration of the +residual "germ-plasm" in the wild seed, when this is first exposed to +the changed conditions of life, due to its growth in a strange kind of +soil--e.g. while germinating in an unusual kind of earth for producing +the first generation. But this would be going a long way to save an +hypothesis. In case, however, it should now be suggested, I may remark +that it would be negatived by the following facts.[79] + + [79] Since the above was written Professor Weismann has advanced, in + _The Germ-plasm_, a suggestion very similar to this. It is + sufficient here to remark, that nearly all the facts and + considerations which ensue in the present chapter are + applicable to his suggestion, the essence of which is + anticipated in the above paragraph. + +In the first place, an endless number of cases might be quoted where +somatogenetic changes thus produced by changed conditions of life are +not hereditary. Therefore, in all these cases it is certainly not the +"germ-plasm" that is affected. In other words, there can be no question +that somatogenetic changes of the kinds above mentioned do very readily +admit of being produced in the first generation by changes of soil, +altitude, &c. And that somatogenetic changes thus produced should not +always--or even generally--prove themselves to be hereditary from the +first moment of their occurrence, is no more than any theory of +heredity would expect. Indeed, looking to the known potency of +reversion, the wonder is that in any case such changes should become +hereditary in a single generation. On the other hand, there is no reason +to imagine that the hypothetical germ-plasm--howsoever _unstable_ we may +suppose it to be--can admit of being directly affected by a change of +soil in a single generation. For, on this view, it must presumably be +chiefly affected during the short time that the seed is germinating; and +during that time the changed conditions can scarcely be conceived as +having any points of attack, so to speak, upon the residual germ-plasm. +There are no roots on which the change of _soil_ can make itself +perceptible, nor any stem and leaves on which the change of _atmosphere_ +can operate. Yet the changed condition's may produce hereditary +modifications in any parts of the plant, which are not only precisely +analogous to non-hereditary changes similarly produced in the somatic +tissues of innumerable other plants, but are always of precisely the +same kind in the same lot of plants that are affected. When all the +radishes grown from wild seed in Paris, for instance, varied in the +direction of rotundity and dark colour, while those grown in the country +presented the opposite characters, we can well understand the facts as +due to an entire season's action upon the whole of the growing plant, +with the result that all the changes produced in each set of plants were +similar--just as in the cases where similarly "climatic" modifications +are not hereditary, and therefore unquestionably due to changed +conditions acting on roots, stems, leaves, or flowers, as the case may +be. On the other hand, it is not thus intelligible that during the +short time of germination the changed conditions should effect a +re-shuffling (or any other modification) of the "germ-plasm" in the +seeds--and this in such a manner that the effect on the residual +germ-plasm reserved for future generations is precisely similar to that +produced on the somatic tissues of the developing embryo. + +In the second place, as we have seen, in some of the foregoing cases the +changes were produced months--and even years--before the seeds of the +first germination were formed. Therefore the hereditary effect, if +subsequent to the period of embryonic germination, must have been +produced on germ-plasm as this occurs diffused through the somatic +tissues. But, if so, we shall have to suppose that such germ-plasm is +afterwards gathered in the seeds when these are subsequently formed. +This supposition, however, would be radically opposed to Weismann's +theory of heredity: nor do I know of any other theory with which it +would be reconcilable, save such as entertain the possibility of the +Lamarckian factors. + +Lastly, in the third place, I deem the following considerations of the +highest importance:-- + + "As other instances in which peculiar structures are now hereditary + may be mentioned aquatic plants and those producing subterraneous + stems. Whether they be dicotyledons or monocotyledons, there is a + fundamental agreement in the anatomy of the roots and stem of + aquatic plants, and, in many cases, of the leaves as well. Such has + hitherto been attributed to the aquatic habit. The inference or + deduction was, of course, based upon innumerable coincidences; the + water being supposed to be the direct cause of the degenerate + structures, which are hereditary and characteristic of such plants + in the wild state. M. Costantin has, however, verified this + deduction, by making terrestrial and aerial stems to grow + underground and in water: the structures _at once_ began to assume + the subterranean or aquatic type, as the case might be; and, + conversely, aquatic plants made to grow upon land _at once_ began + to assume the terrestrial type of structure, while analogous + results followed changes from a subterranean to an aerial position, + and _vice versa_." + +This is also quoted from the Rev. Prof. Henslow's letters to me, and the +important point in it is, that the great changes in question are proved +to be of a purely "somatogenetic" kind; for they occurred "at once" _in +the ready-grown plant_, when the organs concerned were exposed to the +change from aquatic to terrestrial life, or _vice versa_--and also from +a subterranean to an aerial position, or _vice versa_. Consequently, +even the abstract possibility of the changed conditions of life having +operated on the _seed_ is here excluded. Yet the changes are of +precisely the same kind as are now _hereditary_ in the wild species. It +thus appears undeniable that all these remarkable and uniform changes +must originally have been somatogenetic changes; yet they have now +become blastogenetic. This much, I say, seems undeniable; and therefore +it goes a long way to prove that the non-blastogenetic character of the +changes has been due to their originally somatogenetic character. For, +if not, how did natural selection ever get an opportunity of making any +of them blastogenetic, when every individual plant has always presented +them as already given somatogenetically? This last consideration appears +in no small measure to justify the opinion of Mr. Henslow, who +concludes--"These experiments prove, not only that the influence of the +environment is _at once_ felt by the organ; but that it is indubitably +the _cause_ of the now specific and hereditary traits peculiar to +normally aquatic, subterranean, and aerial stems, or roots[80]." + + [80] It also serves to show that Weismann's newer doctrine of + similar "determinants" occurring both in the germ and in the + somatic tissues is a doctrine which cannot be applied to rebut + this evidence of the transmission of acquired characters in + plants. Therefore even its hypothetical validity as applied by + him to explain the seasonal variation of butterflies is + rendered in a high degree dubious. + +He continues to furnish other instances in the same line of proof--such +as the distinctive "habits" of insectivorous, parasitic, and climbing +plants; the difference in structure between the upper and under sides of +horizontal leaves, &c. "For here, as in all organs, we discover by +experiment how easily the anatomy of plants can be affected by their +environment; and that, as long as the latter is constant, so are the +characters of the plants constant and hereditary." + + [The following letter, contributed by Dr. Hill to _Nature_, vol. I. + p. 617, may here be quoted. C. Ll. M. + + "It may be of interest to your readers to know that two guinea-pigs + were born at Oxford a day or two before the death Dr. Romanes, both + of which exhibited a well-marked droop of the left upper eyelid. + These guinea-pigs were the offspring of a male and a female + guinea-pig in both of which I had produced for Dr. Romanes, some + months earlier, a droop of the left upper eyelid by division of the + left cervical sympathetic nerve. This result is a corroboration of + the series of Brown-Séquard's experiments on the inheritance of + acquired characteristics. A very large series of such experiments + are of course needed to eliminate all sources of error, but this I + unfortunately cannot carry out at present, owing to the need of a + special farm in the country, for the proper care and breeding of + the animals.--LEONARD HILL. + + "Physiological Laboratory, Univ. Coll. London, Oct. 18, 1894."] + + + + +CHAPTER V. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(A. and B.) + + +_Direct and Indirect Evidence in favour of the Non-inheritance of +Acquired Characters_[81]. + + [81] [_See_ note appended to Preface. C. LI. M.] + +The strongest argument in favour of "continuity" is that based upon the +immense difference between congenital and acquired characters in respect +of heritability. For that there is a great difference in this respect is +a matter of undeniable fact. And it is obvious that this difference, the +importance of which must be allowed its full weight, is just what we +should expect on the theory of the continuity of the germ-plasm, as +opposed to that of pangenesis. Indeed it may be said that the difference +in question, while it constitutes important _evidence_ in favour of the +former theory, is a _difficulty_ in the way of the latter. But here two +or three considerations must be borne in mind. + +In the first place, this fact has long been one which has met with wide +recognition and now constitutes the main ground on which the theory of +continuity stands. That is to say, it was the previous knowledge of +this contrast between congenital and acquired characters which led to +the formulation of a theory of continuity by Mr. Galton, and to its +subsequent development by Prof Weismann. + +But, in the second place, there is a wide difference between the +certainty of this fact and that of the theory based upon it. The certain +fact is, that a great distinction in respect of heritability is +observable between congenital and acquired characters. The theory, as +formulated by Weismann, is that the distinction is not only great but +absolute, or, in other words, that in no case and in no degree can any +acquired character be ever inherited. This hypothesis, it will be +observed, goes far beyond the observed fact, for it is obviously +possible that, notwithstanding this great difference in regard to +heritability between congenital and acquired characters, the latter may +nevertheless, sometimes and in some degree, be inherited, however much +difficulty we may experience in observing these lesser phenomena in +presence of the greater. The Weismannian hypothesis of _absolute_ +continuity is one thing, while the observed fact of at least a _high +relative degree_ of continuity is quite another thing. And it is +necessary to be emphatic on this point, since some of the reviewers of +my _Examination of Weismannism_ confound these two things. Being +apparently under the impression that it was reserved for Weismann to +perceive the fact of there being a great difference between the +heritability of congenital and acquired characters, they deem it +inconsistent in me to acknowledge this fact while at the same time +questioning the hypothetical basis of his fundamental postulate touching +the absolute continuity of germ-plasm. It is one merit of Galton's +theory, as against Weismann's, that it does not dogmatically exclude the +possible interruption of continuity on some occasions and in some +degree. Herein, indeed, would seem to lie the central core of the whole +question in dispute. For it is certain and has long been known that +individually acquired characters are at all events much less heritable +than are long-inherited or congenital ones. But Lamarckian theory +supposes that congenital characters were in some cases originally +acquired, and that what are now blastogenetic characters were in some +cases at first somatogenetic and have become blastogenetic only in +virtue of sufficiently long inheritance. Since Darwin's time, however, +evolutionists (even of the so-called Lamarckian type) have supposed that +natural selection greatly assists this process of determining which +somatogenetic characters shall become congenital or blastogenetic. Hence +all schools of evolutionists are, and have long been, agreed in +regarding the continuity principle as true in the main. No evolutionist +would at any time have propounded the view that one generation depends +for _all_ its characters on those acquired by its _immediate_ ancestors, +for this would merely be to unsay the theory of Evolution itself, as +well as to deny the patent facts of heredity as shown, for example, in +atavism. At most only some fraction of a _per cent._ could be supposed +to do so. But Weismann's contention is that this principle is not only +true in the main, but _absolutely_ true; so that natural selection +becomes all in all or not at all. Unless Weismannism be regarded as +this doctrine of absolutism it permits no basis for his attempted theory +of evolution. + +And, whatever may be said to the contrary by the more enthusiastic +followers of Prof. Weismann, I must insist that there is the widest +possible difference between the truly scientific question of fact which +is assumed by Weismann as answered (the base-line of the diagram on p. +43), and the elaborate structure of deductive reasoning which he has +reared on this assumption (the Y-like structure). Even if the assumption +should ever admit of inductive proof, the almost bewildering edifice of +deductive reasoning which he has built upon it would still appear to me +to present extremely little value of a scientific kind. Interesting +though it may be as a monument of ingenious speculation hitherto unique +in the history of science, the mere flimsiness of its material must +always prevent its far-reaching conclusions from being worthy of serious +attention from a biological point of view. But having already attempted +to show fully in my _Examination_ this great distinction between the +scientific importance of the question which lies at the base of +"Weismannism," and that of the system which he has constructed on his +assumed answer thereto, I need not now say anything further with regard +to it. + +Again, on the present occasion and in this connexion I should like to +dissipate a misunderstanding into which some of the reviewers of the +work just mentioned have fallen. They appear to have concluded that +because I have criticized unfavourably a considerable number of +Weismann's theories, I have shown myself hostile to his entire system. +Such, however, is by no means the case; and the misunderstanding can +only be accounted for by supposing that the strongly partisan spirit +which these critics display on the side of neo-Darwinism has rendered +them incapable of appreciating any attempt at impartial--or even so much +as independent--criticism. At all events, it is a matter of fact that +throughout the work in question I have been particularly careful to +avoid this misunderstanding as to my own position. Over and over again +it is there stated that, far from having any objection to the principle +of "Continuity" as represented in the base-line of the above diagram, I +have been convinced of its truth ever since reading Mr. Galton's _Theory +of Heredity_ in 1875. All the "hard words" which I have written against +Weismann's system of theories have reference to those parts of it which +go to constitute the Y-like structure of the diagram. + +It is, however, desirable to recur to another point, and one which I +hope will be borne in mind throughout the following discussion. It has +already been stated, a few pages back, that the doctrine of continuity +admits of being held in two very different significations. It may be +held as absolute, or as relative. In the former case we have the +Weismannian doctrine of germ-plasm: the substance of heredity is taken +to be a substance _per se_, which has always occupied a separate +"sphere" of its own, without any contact with that of somatoplasm +further than is required for its lodgement and nutrition; hence it can +never have been in any degree modified as to its hereditary qualities by +use-inheritance or any other kind of somatogenetic change; it has been +_absolutely_ continuous "since the first origin of life." On the other +hand, the doctrine of continuity may be held in the widely different +sense in which it has been presented by Galton's theory of Stirp. Here +the doctrine is, that while for the most part the phenomena of heredity +are due to the continuity of the substance of heredity through +numberless generations, this substance ("Stirp") is nevertheless not +absolutely continuous, but may admit, in small though cumulative +degrees, of modification by use-inheritance and other factors of the +Lamarckian kind. Now this all-important distinction between these two +theories of continuity has been fully explained and thoroughly discussed +in my _Examination_; therefore I will not here repeat myself further +than to make the following remarks. + +The Weismannian doctrine of continuity as absolute (base-line of the +diagram) is necessary for the vast edifice of theories which he has +raised upon it (the Y), first as to the minute nature and exact +composition of the substance of heredity itself ("Germ-plasm"), next as +to the precise mechanism of its action in producing the visible +phenomena of heredity, variation, and all allied phenomena, and, lastly, +the elaborate and ever-changing theory of organic evolution which is +either founded on or interwoven with this vast system of hypothetic +speculation. Galton's doctrine of continuity, on the other hand, is a +"Theory of Heredity," and a theory of heredity alone. It does not meddle +with any other matters whatsoever, and rigidly avoids all speculation +further than is necessary for the bare statement and inductive support +of the doctrine in question. Hence, it would appear that this, the only +important respect wherein the doctrine of continuity as held by Galton +differs from the doctrine as held by Weismann, arisen from the necessity +under which the latter finds himself of postulating _absolute_ +continuity as a logical basis for his deductive theory of the precise +mechanism of heredity on the one hand, and of his similarly deductive +theory of evolution on the other. So far as the doctrine of continuity +is itself concerned (i.e. the question of the inheritance of acquired +characters), there is certainly no more inductive reason for supposing +the continuity absolute "since the first origin of life," than there is +for supposing it to be more or less susceptible of interruption by the +Lamarckian factors. In other words, but for the sake of constructing a +speculative foundation for the support of his further theories as to +"the architecture of germ-plasm" and the factors of organic evolution, +there is no reason why Weismann should maintain the absolute separation +of the "sphere" of germ-plasm from that of somatoplasm. On the contrary, +he has no reason for concluding against even a considerable and a +frequent amount of cutting, or overlapping, on the part of these two +spheres. + +But although this seems to me sufficiently obvious, as I have shown at +greater length in the _Examination of Weismannism_, it must not be +understood that I hold that there is room for any large amount of such +overlapping. On the contrary, it appears to me as certain as anything +can well be that the amount of such overlapping from one generation to +another, if it ever occur at all, must be exceedingly small, so that, +if we have regard to only a few sequent generations, the effects of +use-inheritance, and Lamarckian factors are, at all events as a rule, +demonstrably imperceptible. But this fact does not constitute any +evidence--as Weismann and his followers seem to suppose--against a +possibly important influence being exercised by the Lamarckian factors, +in the way of gradual increments through a long series of generations. +It has long been well known that acquired characters are at best far +less fully and far less certainly inherited than are congenital ones. +And this fact is of itself sufficient to prove the doctrine of +continuity to the extent that even the Lamarckian is rationally bound to +concede. But the fact yields no proof--scarcely indeed so much as a +presumption--in favour of the doctrine of continuity as absolute. For it +is sufficiently obvious that the adaptive work of heredity could not be +carried on at all if there had to be a discontinuity in the substance of +heredity at every generation, or even after any very large number of +generations. + +Little more need be said concerning the arguments which fall under the +headings A and B. The Indirect evidence is considered in Appendix I of +the _Examination of Weismannism_; while the Direct evidence is +considered in the text of that work in treating of Professor Weismann's +researches on the _Hydromedusae_ (pp. 71-76). + +The facts of karyokinesis are generally claimed by the school of +Weismann as making exclusively in favour of continuity as absolute. But +this is a partisan view to take. In any impartial survey it should be +seen that while the facts are fairly interpretable on Weismann's theory, +they are by no means proof thereof. For any other theory of Heredity +must suppose the material of heredity to be of a kind more or less +specialized, and the mechanism of heredity extremely precise and well +ordered. And this is all that the facts of karyokinesis prove. Granting +that they prove continuity, they cannot be held to prove that continuity +to be absolute. In other words, the facts are by no means incompatible +with even a large amount of commerce between germ-plasm and +somato-plasm, or a frequent transmission of acquired characters. + +Again, Weismann's theory, that the somatic and the germ-plasm +determinants may be similarly and simultaneously modified by external +conditions may be extended much further than he has used it himself, so +as to exclude, or at any rate invalidate, _all_ evidence in favour of +Lamarckianism, other than the inheritance of the effects of use and +disuse. All evidence from apparently inherited effects produced by +change of external conditions is thus virtually put out of court, +leaving only evidence from the apparently inherited effects of +functionally produced modifications. And this line of evidence is +invalidated by Panmixia. Hence there remain only the arguments from +selective value and co-adaptation. Weismann meets these by adducing the +case of neuter insects, which have been already considered at sufficient +length. + + +(C.) +_Experimental Evidence as to the Non-inheritance of Acquired +Characters._ + + +Let us now proceed to the experimental evidence which has been adduced +on the side of Weismannism. + +Taking this evidence in order of date, we have first to mention that on +which the school of Weismann has hitherto been satisfied almost +exclusively to rely. This is the line of negative evidence, or the +seeming absence of any experimental demonstration of the inheritance of +acquired characters. This kind of evidence, however, presents much less +cogency than is usually supposed. And it has been shown in the last +chapter that the amount of experimental evidence in favour of the +transmission of acquired characters is more considerable than the school +of Weismann seems to be aware--especially in the vegetable kingdom. I do +not think that this negative line of evidence presents much weight; and, +to show that I am not biassed in forming this judgement, I may here +state that few have more reason than myself for appreciating the weight +of such evidence. For, as already stated, when first led to doubt the +Lamarckian factors, now more than twenty years ago, I undertook a +research upon the whole question--only a part of which was devoted to +testing the particular case of Brown-Séquard's statements, with the +result recorded in the preceding chapter. As this research yielded +negative results in all its divisions--and, not only in the matter of +Brown-Séquard's statements--I have not hitherto published a word upon +the subject. But it now seems worth while to do so, and for the +following reasons. + +First, as just observed, a brief account of my old experiences in this +field will serve to show what good reason I have for feeling the weight +of such negative evidence in favour of Continuity as arises from failure +to produce any good experimental evidence to the contrary. In the second +place, now that the question has become one of world-wide interest, it +would seem that even negative results deserve to be published for +whatever they may be worth on the side of Neo-Darwinism. Lastly, in the +third place, although the research yielded negative results in my hands, +it is perhaps not undesirable to state the nature of it, if only to +furnish suggestions to other physiologists, in whose hands the +experiments--especially in these days of antiseptics--may lead to a +different termination. Altogether I made thousands of experiments in +graft-hydridization (comprising bines, bulbs of various kinds, buds, and +tubers); but with uniformly negative results. With animals I tried a +number of experiments in grafting characteristic congenital tissues from +one variety on another--such as the combs of Spanish cocks upon the +heads of Hamburgs; also, in mice and rats, the grafting together of +different varieties; and, in rabbits and bitches, the transplantation of +ovaries of newly-born individuals belonging to different well-marked +breeds. This latter experiment seems to be one which, if successfully +performed (so that the transplanted ovaries would form their attachment +in a young bitch puppy and subsequently yield progeny to a dog of the +same breed as herself) would furnish a crucial test as to the +inheritance or non-inheritance of acquired characters. Therefore I +devoted to it a large share of my attention, and tried the experiment in +several different ways. But I was never able to get the foreign +ovary--or even any portion thereof--to graft. Eventually the passing of +the Vivisection Act caused me to abandon the whole research as far as +animals were concerned--a research, indeed, of which I had become +heartily tired, since in no one instance did I obtain any adhesion. +During the last few years, however, I have returned to these experiments +under a licence, and with antiseptic precautions, but with a similar +want of success. Perhaps this prolonged and uniformly fruitless +experience may now have the effect of saving the time of other +physiologists, by warning them off the roads where there seems to be no +thoroughfare. On the other hand, it may possibly lead some one else to +try some variation in the method, or in the material, which has not +occurred to me. In particular, I am not without hope that the +transplantation of ovaries in very young animals may eventually prove to +be physiologically possible; and, if so, that the whole issue as between +the rival theories of heredity will be settled by the result of a single +experiment. Possibly some of the invertebrata will be found to furnish +the suitable material, although I have been unable to think of any of +these which present sufficiently well-marked varieties for the purpose. +But, pending the successful accomplishment of this particular experiment +in the grafting of any animal tissue, I think it would be clearly +unjustifiable to conclude against the Lamarckian factors on the ground +of any other experiments yielding negative results in but one generation +or even in a large number of sequent generations. + +For instance, the latter consideration applies to the negative results +of Mr. Francis Galton's celebrated _Experiments in Pangenesis_.[82]. +These consisted in transfusing the blood of one variety of rabbit into +the veins of both sexes of another, and then allowing the latter to +breed together: in no case was there any appearance in the progeny of +characters distinctive of the variety from which the transfused blood +was derived. But, as Mr. Galton himself subsequently allowed, this +negative result constitutes no disproof of pangenesis, seeing that only +a portion of the parents' blood was replaced; that this portion, even if +charged with "gemmules," would contain but a very small number of these +hypothetical bodies, compared with those contained in all the tissues of +the parents; and that even this small proportional number would +presumably be soon overwhelmed by those contained in blood newly-made by +the parents. Nevertheless the experiment was unquestionably worth +trying, on the chance of its yielding a positive result; for, in this +event, the question at issue would have been closed. Accordingly I +repeated these experiments (with the kind help of Professor Schäfer), +but with slight differences in the method, designed to give pangenesis a +better chance, so to speak. + + [82] _Proc. R. S. 1871._ + +Thus I chose wild rabbits to supply the blood, and Himalayan to receive +it--the former being the ancestral type (and therefore giving reversion +an opportunity of coming into play), while the latter, although a +product of domestication, is a remarkably constant variety, and one +which differs very much in size and colour from the parent species. +Again, instead of a single transfusion, there were several transfusions +performed at different times. Moreover, we did not merely allow the +blood of one rabbit to flow into the veins of the other (whereby little +more than half the blood could be substituted); but sacrificed three +wild rabbits for refilling the vascular system of each tame one on each +occasion. Even as thus improved, however, the experiment yielded only +negative results, which, therefore, we never published. + +Subsequently I found that all this labour, both on Mr. Galton's part and +our own, was simply thrown away--not because it yielded only negative +results, but because it did not serve as a crucial experiment at all. +The material chosen was unserviceable for the purpose, inasmuch as +rabbits, even when crossed in the ordinary way, never throw intermediate +characters. Needless to say, had I been aware of this fact before, I +should never have repeated Mr. Galton's experiments--nor, indeed, would +he have originally performed them had he been aware of it. So all this +work goes for nothing. The research must begin all over again with some +other animals, the varieties of which when crossed do throw intermediate +characters. + +Therefore I have this year made arrangements for again repeating the +experiments in question--only, instead of rabbits, using well-marked +varieties of dogs. A renewed attack of illness, however, has +necessitated the surrender of this research to other hands, with a +consequent delay in its commencement. + +My ignorance of the unfortunate peculiarity displayed by rabbits in not +throwing intermediate characters has led to a further waste of time in +another line of experiment. On finding that mammalian ovaries did not +admit of being grafted, it seemed to me that the next best thing to try +would be the transplantation of fertilized ova from one variety to +another, for the purpose of ascertaining whether, if a parturition +should take place under such circumstances, gestation by the uterine +mother would affect the characters of the ovum derived from the ovarian +mother--she, of course, having been fertilized by a male of her own +variety. Of course it was necessary that both the mothers should be in +season at about the same time, and therefore I again chose rabbits, +seeing that in the breeding season they are virtually in a chronic state +of "heat." I selected Himalayans and Belgian hares, because they are +well-marked varieties, breed true, and in respect of colour are very +different from one another. It so happened that while I was at work upon +this experiment, it was also being tried, unknown to me, by Messrs. +Heape and Buckley who, curiously enough, employed exactly the same +material. They were the first to obtain a successful result. Two +fertilized ova of the Angora breed having been introduced into the +fallopian tube of a Belgian hare, developed there in due course, and +gave rise to two Angora rabbits in no way modified by their Belgian hare +gestation[83]. + + [83] _Proc. R. S. 1890_, vol. xlviii. p. 457. It should be stated + that the authors do not here concern themselves with any theory + of heredity. + +But, interesting and suggestive as this experiment is in other +connexions, it is clearly without significance in the present one, for +the reason already stated. It will have to be tried on well-marked +varieties of other species of animals, which are known to throw +intermediate characters. Even, however, if it should then yield a +similarly negative result, the fact would not tell against the +inheritance of acquired characters; seeing that an ovum by the time it +is ripe is a finished product, and therefore not to be expected, on any +theory of heredity, to be influenced as to its hereditary potentialities +by the mere process of gestation. On the other hand, if it should prove +that it does admit of being thus affected, so that against all +reasonable expectation the young animal presents any of the hereditary +characters of its uterine mother, the fact would terminate the question +of the transmission of acquired characters--and this quite as +effectually as would a similarly positive result in the case of progeny +from an ingrafted ovary of a different variety. In point of fact, the +only difference between the two cases would be, that in the former it +_might_ prove possible to close the question on the side of +Lamarckianism, in the latter it would _certainly_ close the question, +either on this side or on the opposite as the event would determine. + +The only additional fact that has hitherto been published by the school +of Weismann is the result of Weismann's own experiment in cutting off +the tails of mice through successive generations. But this experiment +does not bear upon any question that is in debate; for no one who is +acquainted with the literature of the subject would have expected any +positive result to follow from such a line of inquiry. As shown further +back in the text, Darwin had carefully considered the case of +mutilations, and explained that their non-transmissibility constitutes +no valid objection to his theory of pangenesis. Furthermore, it may now +be added, he expressly alluded in this connexion to the cutting off of +tails, as practised by horse-breeders and dog-fanciers, "through a +number of generations, without any inherited effect." He also alluded to +the still better evidence which is furnished by the practice of +circumcision. Therefore it is difficult to understand the object of +Weismann's experiment. Yet, other than the result of this experiment, no +new fact bearing on the question at issue has been even so much as +alleged. + + + + +CHAPTER VI. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_conclusion_[84]). + + [84] _See_ note appended to Preface. C. Ll. M. + +In the foregoing chapters I have endeavoured to be, before all things, +impartial; and if it seems that I have been arguing chiefly in favour of +the Lamarckian principles, this has been because the only way of +examining the question is to consider what has to be said on the +affirmative side, and then to see what the negative side can say in +reply. Before we are entitled to discard the Lamarckian factors _in +toto_, we must be able to destroy all evidence of their action. This, +indeed, is what the ultra-Darwinians profess to have done. But is not +their profession premature? Is it not evident that they have not +sufficiently considered certain general facts of nature, or certain +particular results of experiment, which at all events appear +inexplicable by the theory of natural selection alone? In any case the +present discussion has been devoted mainly to indicating such general +facts and particular results. If I have fallen into errors, either of +statement or of reasoning, it is for the ultra-Darwinians to correct +them; but it may be well to remark beforehand, that any criticism of a +merely general kind touching the comparative paucity of the facts thus +adduced in favour of Lamarckian doctrine, will not stand as a valid +criticism. For, as we have seen in the opening part of the discussion, +even if use-inheritance and direct action of the environment have been +of high importance as factors of organic evolution, it must be in almost +all cases impossible to dissociate their influence from that of natural +selection--at any rate where plants and animals in a state of nature are +concerned. On the other hand, experiments expressly devised to test the +question have not hitherto been carried out. Besides, the facts and +arguments here adduced are but _comparatively_ few. For, unless it can +be shown that what has been said of reflex action, instinct, so-called +"self-adaptation" in plants, &c., is wrong in principle, the facts which +tell in favour of Lamarckian theory are _absolutely_ very numerous. Only +when considered in relation to cases where we are unable to exclude the +conceivable possibility of natural selection having been at work, can it +be said that the facts in question are not numerous. + +Comparatively few, then, though the facts may be of which I have given +some examples, in my opinion they are amply sufficient for the purpose +in hand. This purpose is to show that the question which we are now +considering is very far from being a closed question; and, therefore, +that the school of Weismann is much too precipitate in alleging that +there is neither any necessity for, nor evidence of, the so-called +Lamarckian factors[85]. And this opinion, whatever it may be worth, is +at all events both deliberate and impartial. As one of the first to +doubt the transmission of acquired characters, and as one who has spent +many years in experimental inquiries upon the subject, any bias that I +may have is assuredly against the Lamarckian principles--seeing that +nearly all my experiments have yielded negative results. It was Darwin +himself who checked this bias. But if the ultra-Darwinians of the last +ten years had succeeded in showing that Darwin was mistaken, I should be +extremely glad to fall into line with them. As already shown, however, +they have in no way affected this question as it was left by Galton in +1875. And if it be supposed a matter of but little importance whether we +agree with Galton in largely diminishing the comparative potency of the +Lamarckian principles, or whether we agree with Weismann in abolishing +them together, it cannot be too often repeated that such is an entirely +erroneous view. No matter how faintly or how fitfully acquired +characters may be transmitted, in so far as they are likewise adaptive +characters, their transmission (and therefore their development) must be +cumulative. Hence, the only effect of attenuating our estimate of their +_intensity_, is that of increasing our estimate of their +_duration_--i.e. of the time over which they have to operate in order to +produce important results. And, even so, it is to be remembered that +the importance of such results is not to be estimated by the magnitude +of modification. Far more is it to be estimated by the character of +modification as adaptive. For if functionally produced changes, and +changes produced in adaptive response to the environment, are ever +transmitted in a cumulative manner, a time must sooner or later arrive +when they will reach a selective value in the struggle for +existence--when, of course, they will be rapidly augmented by natural +selection. Thus, if in any degree operative at all, the great function +of these principles must be that of supplying to natural selection those +incipient stages of adaptive modifications in all cases where, but for +their agency, there would have been nothing of the kind to select. +Themselves in no way dependent on adaptive modifications having already +attained a selective value, these Lamarckian principles are (under the +Darwinian theory) direct causes of determinate variation in adaptive +lines; and variation in those lines being cumulative, the result is that +natural selection is in large part presented with the raw material of +its manufacture--special material of the particular kinds required, as +distinguished from promiscuous material of all kinds. And the more +complex the manufacture the more important will be the work of this +subordinate factory. We can well imagine how the shell of a nut, for +instance, or even the protective colouring of an insect, may have been +gradually built up by natural selection alone. But just in proportion as +structures or organs are not merely thus of passive _use_ (where, of +course, the Lamarckian principles cannot obtain), but require to be +actively _used_, in that proportion does it become difficult to +understand the _incipient_ construction of them by natural selection +alone. Therefore, in many such cases, if the incipient construction is +not to be explained by the Lamarckian principles, it is difficult to see +how it is to be explained at all. + + [85] E.g. "The supposed transmission of this artificially produced + disease (epilepsy) is the only definite instance which has been + brought forward in support of the transmission of acquired + characters."--_Essays_, p. 328. + +Furthermore, since the question as to the transmission of acquired +characters stands now exactly as it did after the publication of Mr. +Galton's _Theory of Heredity_ twenty years ago, it would seem that our +judgement with regard to it should remain exactly what it was then. +Although we must "out-Darwin Darwin" to the extent of holding that he +assigned too large a measure of intensity to the Lamarckian factors, no +sufficient reason has been shown for denying the existence of these +factors _in toto_; while, on the other hand, there are certain general +considerations, and certain particular facts, which appear to render it +probable that they have played a highly important part in the process of +organic evolution as a whole. At the same time, and in the present state +of our information, this judgement must be deemed provisional, or liable +eventually to be overturned by experimental proof of the non-inheritance +of acquired characters. But, even if this should ever be finally +accomplished, the question would still remain whether the principle of +natural selection alone is capable of explaining all the facts of +adaptation; and, for my own part, I should then be disposed to believe +that there must be some other, though hitherto undiscovered, principle +at work, which co-operates with natural selection, by playing the +subordinate role which was assigned by Darwin to the principles of +Lamarck. + +Finally, let it be noted that no part of the foregoing argument is to be +regarded as directed against the _principle_ of what Professor Weismann +calls "continuity." On the contrary, it appears to be self-evident that +this principle must be accepted in some degree or another by every one, +whether Darwinians, Neo-Darwinians, Lamarckians, Neo-Lamarckians, or +even the advocates of special creation. Yet, to hear or to read some of +the followers of Weismann, one can only conclude that, prior to his +publications on the subject, they had never thought about it at all. +These naturalists appear to suppose that until then the belief of +Darwinians was, that there could be no hereditary "continuity" between +any one organic type and another (such, for instance, as between Ape and +Man), but that the whole structure of any given generation must be due +to "gemmules" or "somato-plasm," derived exclusively from the preceding +generation. Nothing can show more ignorance, or more thoughtlessness, +with regard to the whole subject. The very basis of the general theory +of evolution is that there must always have been a continuity in the +material substance of heredity since the time when the process of +evolution began; and it was not reserved for our generation, or even for +our century, to perceive the special nature of this material substance +in the case of sexual organisms. No, the real and the sole question, +where Weismann's theory of heredity is concerned, is simply this--Are we +to hold that this material substance has been _absolutely_ continuous +"since the first origin of sexual propagation," always occupying a +separate "sphere" of its own, at all events to the extent of never +having been modified by the body substance in which it resides +(Lamarckian factors); _or_, are we to hold that this "germ-plasm," +"stirp," or "formative-material," has been but _relatively_ continuous, +so as to admit of some amount of commerce with body-substance, and +therefore to admit of acquired characters, when sufficiently long +continued as such, eventually becoming congenital? If this question be +answered in the latter sense, of course the further question arises as +to the _degree_ of such commerce, or the _time_ during which acquired +characters must continue to be acquired in successive generations before +they can sufficiently impress themselves on the substance of heredity to +become congenital. But this is a subordinate question, and one which, in +the present state of our information, it seems to me almost useless to +speculate upon. My own opinion has always been the same as that of Mr. +Galton; and my belief is that eventually both Weismann and his followers +will gravitate into it. It was in order to precipitate this result as +far as possible that I wrote the _Examination_. If it ever should be +accomplished, Professor Weismann's elaborate theory of evolution will +have had its bases removed. + + + + +SECTION II + +_UTILITY_ + + + + +CHAPTER VII. + +CHARACTERS AS ADAPTIVE AND SPECIFIC. + + +One of the great changes which has been wrought in biological science by +the Darwinian theory of natural selection, consists in its having +furnished an intelligible explanation of the phenomena of _adaptation_. +Indeed, in my opinion, this is the most important function which this +theory has had to perform; and although we still find systematic +zoologists and systematic botanists who hold that the chief merit of +Darwin's work consists in its having furnished an explanation of the +origin of _species_, a very little consideration is enough to show that +such an idea is but a survival, or a vestige, of an archaic system of +thought. So long as species were regarded as due to separate acts of +creation, any theory which could explain their production by a process +of natural evolution became of such commanding importance in this +respect, that we cannot wonder if in those days the principal function +of Darwin's work was held to be what the title of that work--_The Origin +of Species by means of Natural Selection_--itself serves to convey. And, +indeed, in those days this actually was the principal function of +Darwin's work, seeing that in those days the _fact_ of evolution +itself, as distinguished from its _method_, had to be proved; and that +the whole proof had to stand or fall with the evidence which could be +adduced touching the mutability of species. Therefore, without question, +Darwin was right in placing this issue as to the stability or +instability of species in the forefront of his generalizations, and +hence in constituting it the title of his epoch-making book. But +nowadays, when the fact of evolution has been sufficiently established, +one would suppose it self-evident that the theory of natural selection +should be recognized as covering a very much larger field than that of +explaining the origin of _species_--that it should be recognized as +embracing the whole area of organic nature in respect of _adaptations_, +whether these happen to be distinctive of species only, or of genera, +families, orders, classes, and sub-kingdoms. For it follows from the +general fact of evolution that species are merely arbitrary divisions, +which present no deeper significance from a philosophical point of view +than is presented by well-marked varieties, out of which they are in all +cases believed to have arisen, and from which it is often a matter of +mere individual taste whether they shall be separated by receiving the +baptism of a specific name. Yet, although naturalists are now +unanimously agreed that what they classify as species are nothing +more than pronounced--and in some greater or less degree +permanent--varieties, so forcible is the influence of traditional modes +of thought, that many zoologists and botanists still continue to regard +the origin of species as a matter of more importance than the origin of +adaptations. Consequently, they continue to represent the theory of +natural selection as concerned, primarily, with explaining the origin of +species, and denounce as a "heretic" any one who regards the theory as +primarily a theory of the origin and cumulative development of +adaptations--whether structural or instinctive, and whether the +adaptations are severally characteristic of species only or of any of +the higher taxonomic divisions. Indeed, these naturalists appear to deem +it in some way a disparagement of the theory to state that it is, +primarily, a theory of adaptations, and only becomes secondarily a +theory of species in those comparatively insignificant cases where the +adaptations happen to be distinctive of the lowest order of taxonomic +division--a view of the matter which may fitly be compared to that of an +astronomer who should define the nebular hypothesis as a theory of the +origin of Saturn's rings. It is indeed a theory of the origin of +Saturn's rings; but only because it is a theory of the origin of the +entire solar system, of which Saturn's rings form a part. Similarly, the +theory of natural selection is a theory of the entire system of organic +nature in respect of adaptations, whether these happen to be distinctive +of particular species only, or are common to any number of species. + +Now the outcry which has been raised over this definition of the theory +of natural selection is a curious proof of the opposition which may be +furnished by habitual modes of thought to an exceedingly plain matter of +definition. For, I submit, that no one can deny any of the following +propositions; nor can it be denied that from these propositions the +foregoing definition of the theory in question follows by way of +necessity. The propositions are, first, that natural selection is taken +to be the agency which is mainly, if not exclusively, concerned in the +evolution of adaptive characters: secondly, that these characters, when +evolved, are in some cases peculiar to single species only, while in +other cases, and in process of time, they become the common property of +many species: thirdly, that in cases where they are peculiar to single +species only, they constitute at all events one of the reasons (or even, +as the ultra-Darwinians believe, the only reason) why the particular +species presenting them have come to be species at all. Now, these being +the propositions on which we are all agreed, it obviously follows, of +logical necessity, that the theory in question is primarily one which +explains the existence of adaptive characters wherever these occur; and, +therefore, whether they happen to be restricted to single species, or +are common to a whole group of species. Of course in cases where they +are restricted to single species, the theory which explains the origin +of these particular adaptations becomes also a theory which explains the +origin of these particular species; seeing that, as we are all agreed, +it is in virtue of such particular adaptations that such particular +species exist. Yet even in these cases the theory is, primarily, a +theory of the adaptations in virtue of which the particular species +exists; for, _ex hypothesi_, it is the adaptations which condition the +species, not the species the adaptations. But, as just observed, +adaptations may be the common property of whole groups of species; and +thus the theory of natural selection becomes a theory of the origin of +genera, of families, of orders, and of classes, quite as much as it is a +theory of the origin of species. In other words, it is everywhere a +theory of adaptations; and it is only where the adaptations happen to be +restricted to single species that the theory therefore and incidentally +becomes also a theory of the particular species which presents them. +Hence it is by no means the same proposition to affirm that the theory +of natural selection is a theory of the origin of species, and that it +is a theory of the origin of adaptations, as some of my critics have +represented it to be; for these two things are by no means conterminous. +And in as far as the two propositions differ, it is perfectly obvious +that the latter is the true one. + +Possibly, however, it may be said--Assuredly natural selection is a +theory of the origin (i.e. cumulative development) of adaptations; and, +no less assuredly, although species owe their origin to such +adaptations, there is now no common measure between these two things, +seeing that in numberless cases the same adaptations are the common +property of numberless species. But, allowing all this, we must still +remember that in their _first beginnings_ all these adaptations must +have been distinctive of, or peculiar to, some one particular species, +which afterwards gave rise to a whole genus, family, order, or class of +species, all of which inherited the particular adaptations derived from +this common ancestor, while progressively gaining additional adaptive +characters severally distinctive of their subsequently diverging lines +of descent. So that really all adaptive characters must originally have +been specific characters; and therefore there is no real distinction to +draw between natural selection as a theory of species and as a theory of +adaptations. + +Well, if this objection were to be advanced, the answer would be +obvious. Although it is true that every adaptive character which is now +common to a group of species must originally have been distinctive of a +single parent species, it by no means follows that in its first +beginning as a specific character it appeared in the fully developed +form which it now presents as a generic, family, ordinal, or yet higher +character. On the contrary, it is perfectly certain that in the great +majority of instances such cannot possibly have been the case; and the +larger the group of species over which any particular adaptive character +now extends, the more evidently do we perceive that this character must +itself have been the product of a gradual evolution by natural selection +through an innumerable succession of species in branching lines. The +wing of a bird, for example, is an adaptive structure which cannot +possibly have ever appeared suddenly as a merely specific character: it +must have been slowly elaborated through an incalculable number of +successive species, as these branched into genera, families, and orders +of the existing class. So it is with other class distinctions of an +adaptive kind; and so, in progressively lessening degrees, is it with +adaptive characters of an ordinal, a family, or a generic value. That is +to say, in _all_ cases where an adaptive structure is common to any +considerable group of species, we meet with clear evidence that the +structure has been the product of evolution through the ancestry of +those species; and this evidence becomes increasingly cogent the higher +the taxonomic value of the structure. Indeed, it may be laid down as a +general rule, that the greater the _degree_ of adaptation the greater is +its _diffusion_--both as regards the number of species which present it +now, and the number of extinct species through which it has been handed +down, in an ever ramifying extension and in an ever improving form. +Species, therefore, may be likened to leaves: successive and transient +crops are necessary for the gradual building up of adaptations, which, +like the woody and permanent branches, grow continuously in importance +and efficiency through all the tree of life. Now, in my view, it is the +great office of natural selection to see to the growth of these +permanent branches; and although natural selection has likewise had an +enormously large share in the origination of each successive crop of +leaves--nay, let it be granted to the ultra-Darwinians for the sake of +argument, an exclusive prerogative in this respect--still, in my view, +this is really the least important part of its work. Not as an +explanation of those merely permanent varieties which we call species, +but as an explanation of the adaptive machinery of organic nature, which +has led to the construction both of the animal and vegetable kingdoms in +all their divisions do I regard the Darwinian theory as one of the +greatest generalizations in the history of science. + + * * * * * + +I have dwelt thus at some length upon a mere matter of definition +because, as we shall now find, although it is but a matter of +definition, it is fraught with consequences of no small importance to +the general theory of descent. Starting from an erroneous definition of +the theory of natural selection as primarily a theory of the origin of +species, both friends and foes of the theory have concluded that the +principle of utility must by hypothesis be of universal occurrence so +far as species are concerned; whereas, if once these naturalists were to +perceive that their definition of the theory is erroneous, they would +likewise perceive that their conclusion cannot follow deductively from +the theory itself. If such a conclusion is to be established at all, it +can only be by other and independent evidence of the inductive kind--to +wit, by actual observation. + +Hence we see the importance of starting with an accurate definition of +the theory before proceeding to examine the doctrine of utility as of +universal application to species--a doctrine which, as just stated, has +been habitually and expressly deduced from the theory. This doctrine +occurs in two forms; or, more correctly, there are with reference to +this subject two distinct doctrines, which partly coincide and partly +exclude one another. First, it is held by some naturalists that all +species must necessarily owe their origin to natural selection. And +secondly, it is held by other naturalists, that not only all species, +but likewise all specific characters must necessarily do the same. Let +us consider these two doctrines separately. + +The first, and less extensive doctrine, rests on the deduction that +every species must owe its differentiation as a species to the evolution +of at least one adaptive character, which is peculiar to that species. +Although, when thus originated, a species may come to present any +number of other peculiar characters of a non-adaptive kind, these merely +indifferent peculiarities are supposed to hang, as it were, on the peg +supplied by the one adaptive peculiarity; it is the latter which +conditions the species, and so furnishes an opportunity for any number +of the former to supervene. But without the evolution of at least one +adaptive character there could have been no distinct species, and +therefore no merely adventitious characters as belonging to that +species. I will call this the Huxleyan doctrine, because Professor +Huxley is its most express and most authoritative supporter. + +The second and more extensive doctrine I will call, for the same reason, +the Wallacean doctrine. This is, as already stated, that it follows +deductively from the theory of natural selection, that not only all +species, but even all the distinctive characters of every species, must +necessarily be due to natural selection; and, therefore, can never be +other than themselves useful, or, at the least, correlated with some +other distinctive characters which are so. + +Here, however, I should like to remark parenthetically, that in choosing +Professor Huxley and Mr. Wallace as severally representative of the +doctrines in question, I earnestly desire to avoid any appearance of +discourtesy towards such high authorities. + +I am persuaded--as I shall hereafter seek to show Darwin was +persuaded--that the doctrine of utility as universal where species are +concerned, is, in both the above forms, unsound. But it is less +detrimental in its Huxleyan than in its Wallacean form, because it does +not carry the erroneous deduction to so extreme a point. Therefore let +us first consider the doctrine in its more restricted form, and then +proceed, at considerably greater length, to deal with it in its more +extended form. + + * * * * * + +The doctrine that all _species_ must necessarily be due to natural +selection, and therefore must severally present at least one adaptive +character, appears to me doubly erroneous. + +In the first place, it is drawn from what I have just shown to be a +false premiss; and, in the second place, the conclusion does not follow +even from this premiss. That the premiss--or definition of the theory as +primarily a theory of the origin of species--is false, I need not wait +again to argue. That the conclusion does not follow even from this +erroneous premiss, a very few words will suffice to prove. For, even if +it were true that natural selection is primarily a theory of the origin +of species, it would not follow that it must therefore be a theory of +the origin of _all_ species. This would only follow if it were first +shown that the theory is not merely _a_ theory of the origin of species, +but _the_ theory of the origin of species--i.e. that there can be no +further theory upon this subject, or any cause other than natural +selection which is capable of transforming any single specific type. + +Needless to say, this cannot be shown by way of deduction from the +theory of natural selection itself--which, nevertheless, is the only way +whereby it is alleged that the doctrine is arrived at[86]. + + [86] For a full treatment of Professor Huxley's views upon this + subject, see Appendix II. + + * * * * * + +From the doctrine of utility as advocated by Professor Huxley, we may +now pass on to consider it in the much more comprehensive form advocated +by Mr. Wallace. Of course it is obvious that if the doctrine is +erroneous in its Huxleyan form, much more must it be so in its +Wallacean; and, therefore, that having shown its erroneousness in its +less extended application, there is little need to consider it further +in its more extended form. Looking, however, to its importance in this +more extended application, I think we ought to examine it independently +as thus presented by Mr. Wallace and his school. Let us therefore +consider, on its own merits, the following statement:--It follows +directly from the theory of natural selection that not only all species, +but likewise all specific characters, must be due to natural selection, +and, therefore, must all be of use to the species which present them, or +else correlated with other characters which are so. + +It seems worth while to observe, _in limine_, that this doctrine is +contradicted by that of Professor Huxley. For supposing natural +selection to be the only principle concerned in the origin of all +species, it by no means follows that it is the sole agency concerned in +the origin of all specific characters. It is enough for the former +proposition if only some of the characters distinctive of any given +species--nay, as he very properly expresses it, if only one such +character--has been due to natural selection; for it is clear that, as +he adds, "any number of indifferent [specific] characters" may thus have +been furnished with an opportunity, so to speak, of being produced by +causes other than natural selection. Hence, as previously remarked, the +Huxleyan doctrine, although coinciding with the Wallacean up to the +point of maintaining utility as the only principle which can be +concerned in the origin of species, designedly excludes the Wallacean +doctrine where this proceeds to extend any similar deduction to the case +of specific characters[87]. + + [87] Professor Huxley's views upon this matter are quoted _in + extenso_ in Appendix II. + +In the next place, and with special reference to the Wallacean doctrine, +it is of importance to observe that, up to a certain point there is +complete agreement between Darwinists of all schools. We all accept +natural selection as a true cause of the origin of species (though we +may not all subscribe to the Huxleyan deduction that it is necessarily a +cause of the origin of _all_ species). Moreover, we agree that specific +characters are often what is called rudimentary or vestigial; and, once +more, that our inability to detect the use of any given structure or +instinct is no proof that such a structure or instinct is actually +useless, seeing that it may very probably possess some function hitherto +undetected, or possibly undetectable. Lastly, we all agree that a +structure which is of use may incidentally entail the existence of some +other structure which is not of use; for, in virtue of the so-called +principle of correlation, the useless structure may be an indirect +consequence of natural selection, since its development may be due to +that of the useful structure, with the growth of which the useless one +is correlated. + +Nevertheless, while fully conceding all these facts and principles to +the Wallacean party, those who think with Professor Huxley--and still +more, of course, those few naturalists who think as I do--are unable +to perceive that they constitute any grounds for holding the doctrine +that all specific _characters_ are, or formerly have been, directly or +indirectly due to natural selection. My own reasons for dissenting from +this Wallacean doctrine are as follows. + + * * * * * + +From what has just been said, it will be apparent that the question in +debate is not merely a question of fact which can be settled by a direct +appeal to observation. If this were the case, systematic naturalists +could soon settle the question by their detailed knowledge of the +structures which are severally distinctive of any given group of +species. But so far is this from being the case, that systematic +naturalists are really no better qualified to adjudicate upon the matter +than are naturalists who have not devoted so much of their time to +purely diagnostic work. The question is one of general principles, and +as such cannot be settled by appeals to special cases. For example, +suppose that the rest of this chapter were devoted to a mere enumeration +of cases where it appears impossible to suggest the utility of certain +specific characters, although such cases could be adduced by the +thousand, how should I be met at the end of it all? Not by any one +attempting to suggest the utility, past or present, of the characters +named; but by being told that they must all present some _hidden_ use, +must be _vestigial_, or else must be due to _correlation_. By appealing +to one or other of these assumptions, our opponents are always able to +escape the necessity of justifying their doctrine in the presence of +otherwise inexplicable facts. No matter how many seemingly "indifferent +characters" we may thus accumulate, Mr. Wallace and his followers will +always throw upon us the impossible burden of proving the negative, that +these apparently useless characters do _not_ present some hidden or +former use, are _not_ due to correlation, and therefore have _not_ been +produced by natural selection. It is in vain to retort that the burden +of proof really lies the other way, or on the side of those who affirm +that there is utility where no man can see it, or that there is +correlation where no one can detect it. Thus, so far as any appeal to +particular facts is concerned, it does not appear that there is any +_modus vivendi_. Our opinions upon the question are really determined by +the views which we severally take on matters of general principle. The +issue, though it has a biological bearing, is a logical issue, not a +biological one: it turns exclusively on those questions of definition +and deduction with which we have just been dealing. + +But although it thus follows that we cannot determine in fact what +proportion of apparently useless characters are or are not really +useful, we may very easily determine in fact what proportion of specific +characters _fail to present any observable evidences of utility_. Yet, +even upon this question of observable fact, it is surprising to note the +divergent statements which have of late years been made by competent +writers; statements in fact so divergent that they can only be explained +by some want of sufficient thought on the part of those naturalists who +are antecedently persuaded that all specific characters must be either +directly or indirectly due to natural selection. Hence they fail to give +to apparently useless specific characters the attention which, apart +from any such antecedent persuasion, they deserve. For example, a few +years ago I incidentally stated in a paper before the Linnaean Society, +that "a large proportional number of specific characters" are of a +trivial and apparently unmeaning kind, to which no function admits of +being assigned, and also stated that Darwin himself had expressly given +utterance to the same opinion. When these statements were made, I did +not anticipate that they would be challenged by anybody, except perhaps, +by Mr. Wallace. And, in order now to show that my innocence at that time +was not due to ignorance of contemporary thought on such matters, a +sentence may here be quoted from a paper which was read at the meeting +of the British Association of the same year, by a highly competent +systematic naturalist, Mr. Henry Seebohm, and soon afterwards +extensively republished. Criticizing adversely my then recently +published paper, he said:-- + + "I fully admit the truth of this statement; and I presume that few + naturalists would be prepared to deny that 'distinctions of + specific value frequently have reference to structures which are + without any utilitarian significance[88].'" + + [88] _Geographical Distribution of the Family Charadriidae_, p. 19. + +But since that time the course of Darwinian speculation has been greatly +influenced by the writings of Weismann, who, among other respects in +which he out-darwins Darwin, maintains the doctrine of utility as +universal. In consequence of the influence which these writings have +exercised, I have been more recently and extensively accused of "heresy" +to Darwinian principles, for having stated that "a large proportional +number of specific characters" do not admit of being proved useful, or +correlated with other characters that are useful. Now, observe, we have +here a simple question of fact. We are not at present concerned with the +question how far the argument from ignorance may be held to apply in +mitigation of such cases; but we are concerned only with the question of +fact, as to what proportional number of cases actually occur where we +are _unable to suggest_ the use of specific characters, or the useful +characters with which these apparently useless ones are correlated. I +maintain, as a matter of fact, that the cases in question embrace "a +large proportional number of specific characters." On the other hand, I +am accused of betraying ignorance of species, and of the work of +"species-makers," in advancing this statement; and have been told by Mr. +Wallace, and others of his school, that there is absolutely no evidence +to be derived from nature in support of my views. Well, in the first +place, if this be the case, it is somewhat remarkable that a large body +of competent naturalists, such as Bronn, Broca, Nägeli, Kerner, Sachs, +De Vries, Focke, Henslow, Haeckel, Kölliker, Eimer, Giard, Pascoe, +Mivart, Seebohm, Lloyd Morgan, Dixon, Beddard, Geddes Gulick, and also, +as we shall presently see, Darwin himself, should have fallen into the +same error. And it is further remarkable that the more a man devotes +himself to systematic work in any particular department--whether as an +ornithologist, a conchologist, an entomologist, and so forth--the less +is he disposed to accept the dogma of specific characters as universally +adaptive characters. But, in the second place, and quitting +considerations of mere authority, I appeal to the facts of nature +themselves; and will now proceed, as briefly as possible, to indicate +the result of such an appeal. + +For the following reasons, that birds and mammals seem to furnish the +best field for testing the question by direct observation. First, these +classes present many genera which have been more carefully worked out +than is usually the case with genera of invertebrates, or even of +cold-blooded vertebrates. Secondly, they comprise many genera each +including a large number of species, whose habits and conditions of life +are better known than is the case with species belonging to large genera +of other classes. Thirdly, as birds and mammals represent the highest +products of evolution in respect of organization, a more severe test is +imposed than could be imposed elsewhere, when the question is as to the +utility of specific characters; for if these highest products of +organization fail to reveal, in a large proportional number of cases, +the utility of their specific characters, much more is this likely to be +the case among organic beings which stand lower in the scale of +organization, and therefore, _ex hypothesi_, are less elaborate products +of natural selection. Fourthly, and lastly, birds and mammals are the +classes which Mr. Wallace has expressly chosen to constitute his ground +of argument with regard to the issue on which we are now engaged. + +It would take far too long to show, even in epitome, the results of this +inquiry. Therefore I will only state the general upshot. Choosing genera +of birds and mammals which contain a large number of species whose +diagnostic characters have been worked out with most completeness, I +restricted the inquiry to specific distinctions of colour, not only for +the sake of having a uniform basis for comparisons, but still more +because it seemed that the argument from our ignorance of possibly +unknown uses could be more successfully met in the case of slight +differences of colour or of shading, than in that of any differences of +structure or of form. Finally, after tabulating all the differences of +colour which are given as diagnostic of each species in a genus, and +placing in one column those which may conceivably be useful, while +placing in another column those of which it appeared inconceivable that +any use could be suggested, I added up the figures in the two columns, +and thus obtained a grand total of all the specific characters of the +genus in respect of colours, separated into the two classes of +conceivably useful and apparently useless. Now, in all cases the +apparently useless characters largely preponderated over the conceivably +useful ones; and therefore I abundantly satisfied myself regarding the +accuracy of my previous statement, that a large proportional number--if +not an actual majority--of specific characters belong to the latter +category. + +The following is a brief abstract of these results. + +With respect to Birds, a large number of cases were collected wherein +the characters of allied species differ from one another in such minute +respects of colour or shading, that it seemed unreasonable to suppose +them due to any selective value to the birds in question. It is +needless--even if it were practicable on the present occasion--to +adduce this evidence in detail, since an exceedingly good sample of it +may be found in a small book which is specially devoted to considering +the question in its relation to birds. I allude to an essay by Mr. +Charles Dixon, entitled _Evolution without Natural Selection_ (1885). In +this work Mr. Dixon embodies the results of five years' "careful working +at the geographical distribution and variations of plumage of +Palaearctic birds and their allies in various other parts of the world"; +and shows, by a large accumulation of facts, not only that there is no +utility to be suggested in reference to the minute or trivial +differences of colouration which he describes; but also that these +differences are usually correlated with isolation on the one hand, or +with slight differences of climate on the other. Now it will be shown +later on that both these agents can be proved, by independent evidence, +capable of inducing changes of specific type without reference to +utility: therefore the correlation which Mr. Dixon unquestionably +establishes between apparently useless (because utterly trivial) +specific distinctions on the one hand, and isolation or climatic change +on the other, constitutes additional evidence to show that the +uselessness is not only apparent, but real. Moreover I have collected a +number of cases where such minute differences of colour between allied +species of birds happen to affect parts of the plumage which are +_concealed_--as for instance, the breast and abdomen of creepers. In +such cases it seems impossible to suggest how natural selection can have +operated, seeing that the parts affected are not exposed to the view +either of enemies or of prey. + +Analogous illustrations to any amount may be drawn from Mammals. For +instance, I have worked through the Marsupials with the aid of Mr. +Oldfield Thomas' diagnostic description of their numerous species. Now, +let us take any one of the genera, such as the kangaroos. This comprises +23 species living on an island continent of high antiquity, and not +exposed to the depredations of any existing carnivorous enemies; so that +there is here no present need to vary colour for purposes of protection. +Moreover, in all cases the diagnostic distinctions of colour are so +exceedingly trivial, that even if large carnivora were recently abundant +in Australia, no one could reasonably suggest that the differences in +question would then have been protective. On an average, each of the 23 +species presents rather more than 20 peculiarities of shading, which are +quoted as specifically diagnostic. Altogether there are 474 of these +peculiarities distributed pretty evenly among the 23 species; and in no +case can I conceive that utility can be suggested. + + * * * * * + +Hitherto we have been considering the question of fact, as to whether "a +large proportional number of specific characters" do or do not admit of +having their utility demonstrated, or even so much as plausibly +suggested. In the result, I can only conclude that this question of fact +is really not an open one, seeing that it admits of an abundantly +conclusive answer by any naturalist who will take the trouble to work +through the species of any considerable number of genera in the way +above indicated. But although the question of fact is thus really +closed, there remains a more ultimate question as to its theoretical +interpretation. For, as already pointed out, no matter how great an +accumulation of such facts may be collected, our opponents are always +able to brush them aside by their _a priori_ appeal to the argument from +ignorance. In effect they say--We do not care for any number of +thousands of such facts; it makes no difference to us what "proportional +number" of specific characters fail to show evidence of utility; you are +merely beating the air by adducing them, for we are already persuaded, +on antecedent grounds, that _all_ specific characters _must_ be either +themselves useful, or correlated with others that are, whether or not we +can perceive the utility, or suggest the correlation. + +To this question of theoretical interpretation, therefore, we must next +address ourselves. And here, first of all, I should like to point out +how sturdy must be the antecedent conviction of our opponents, if they +are to maintain it in the face of such facts as have just been adduced. +It must be remembered that this antecedent conviction is of a most +uncompromising kind. By its own premisses it is committed to the +doctrine that _all_ specific characters, without a single exception, +_must_ be either useful, vestigial, or correlated. Well, if such be the +case, is it not somewhat astonishing that out of 474 differences of +colour which are distinctive of the 23 species of the genus Macropus, no +single one appears capable of having any utility demonstrated, or indeed +so much as suggested? For even the recent theory that slight differences +of colour, which cannot be conceived as serving any other purpose, may +enable the sexes of the same species quickly to recognize each other, is +not here available. The species of the genus Macropus are more +conspicuously distinguished by differences of size and form than by +these minute differences of colour; and therefore no such use can be +attributed to the latter. And, as previously stated, even within the +order Marsupialia the genus Macropus is not at all exceptional in this +respect; so that by including other genera of the order it would be easy +to gather such apparently indifferent specific characters by the +hundred, without any one of them presenting evidence--or even +suggestion--of utility. How robust therefore is the faith of an _a +priori_ conviction which can stand against such facts as these! What, +then, are the _a priori_ grounds on which it stands? Mr. Wallace, the +great leader of this school of thought, says:-- + + "It is a necessary deduction from the theory of natural selection, + that none of the definite facts of organic nature, no special + organ, no characteristic form or marking, no peculiarities of + instinct or of habit, no relations between species or between + groups of species, can exist, but which must now be, or once have + been, _useful_ to the individuals or the races which possess + them[89]." + + [89] _Contributions to the Theory of Natural Selection_, p. 47 + (1870); republished in 1892. + +Here, then, we have in brief compass the whole essence of our opponents' +argument. It is confessedly an argument _a priori_, a deduction from the +theory of natural selection, a supposed consequence of that theory which +is alleged to be so necessary that to dispute the consequence is +tantamount to denying the theory from which it is derived. In short, as +before stated, it is a question of theory, not a question of fact: our +difference of opinion is logical, not biological: it depends on our +interpretation of principles, not on our observation of species. It will +therefore be my endeavour to show that the reasoning in question is +fallacious: that it is _not_ a necessary deduction from the theory of +natural selection that no characteristic form or marking, no +peculiarities of instinct or of habit, can exist, but which must now be, +or once have been, useful, or correlated with some other peculiarity +that is useful. + +"The tuft of hair on the breast of a wild turkey-cock _cannot be of any +use_, and it is doubtful whether it can be ornamental in the eyes of the +female bird;--indeed, had the tuft appeared under domestication, it +would have been called a monstrosity[90]." + + [90] _Origin of Species_, p. 70: italics mine. + +As a matter of common sense, unprejudiced by dogma, this appears to be a +perfectly sound judgement; but if Wallace had asked Darwin to prove such +a negative, Darwin could only have replied that it was for Wallace to +prove the affirmative--and thus the issue would have been thrown back +upon a discussion of general principles. Then Wallace would have +said--"The assertion of inutility in the case of any organ or +peculiarity which is not a rudiment or a correlation _is not, and can +never be_, the statement of a fact, but _merely an expression of our +ignorance of its purpose or origin_[91]." Darwin, however, would have +replied:--"Our ignorance of the laws of variation is profound"; and +while, on this account, we ought "to be extremely cautious in +_pretending to decide what structures are now, or have formerly been, of +use to each species_," in point of fact "there can be little doubt that +the tendency to vary in the same manner has _often_ been so strong, that +_all_ individuals of the same _species_ have been similarly modified +_without the aid of any form of selection_[92]." + + [91] _Darwinism_, p. 137: italics mine. + + [92] _Origin of Species_, p. 72: Mr. Wallace himself quotes this + passage (_Darwinism_, p. 141); but says with regard to it "the + important word 'all' is probably an oversight." In the Appendix + (II), on Darwin's views touching the doctrine of utility I + adduce a number of precisely equivalent passages, derived from + all his different works on evolution, and _every one of them_ + presenting "the important word 'all.'" + +It will be my endeavour in the following discussion to show that Darwin +would have had an immeasurable advantage in this imaginary debate. + +To begin with, Wallace's deductive argument is a clear case of circular +reasoning. We set out by inferring that natural selection is a cause +from numberless cases of observed utility as an effect: yet, when "in a +large proportional number" of cases we fail to perceive any imaginable +utility, it is argued that nevertheless utility must be there, since +otherwise natural selection could not have been the cause. + +Be it observed, in any given case we may properly anticipate utility as +_probable_, even where it is not perceived; because there are already so +enormous a number of cases where it is perceived, that, if the principle +of natural selection be accepted at all, we must conclude with Darwin +that it is "the _main_ means of modification." Therefore, in particular +cases of unperceived utility we may take this antecedent probability as +a guide in our biological researches--as has been done with such +brilliant success both by Darwin and Wallace, as well as by many of +their followers. But this is a very different thing from laying down the +universal maxim, that in _all_ cases utility _must_ be present, whether +or not we shall ever be able to detect it[93]. For this universal maxim +amounts to an assumption that natural selection has been the +"_exclusive_ means of modification." That it has been "the main means of +modification" is proved by the generality of the observed facts of +adaptation. That it has been "the exclusive means of modification," with +the result that these facts are universal, cannot be thus proved by +observation. Why, then, is it alleged? Confessedly it is alleged by way +of deduction from the theory of natural selection itself. Or, as above +stated, after having deduced the theory from the facts, it is sought to +deduce the facts from the theory. + + [93] See Introductory Chapter, p. 20. + +Thus far I have been endeavouring to show that the universality of +adaptation cannot be inferred from its generality, or from the theory of +natural selection itself. But, of course, the case would be quite +different if there were any independent evidence--or rather, let us say, +any logical argument--to show that natural selection is "the exclusive +means of modification." For in this event it would no longer involve +circular reasoning to maintain that all specific characters are likewise +adaptive characters. It might indeed appear antecedently improbable that +no other principle than natural selection can possibly have been +concerned in the differentiation of those relatively permanent varieties +which we call species--that in all the realm of organic nature, and in +all the complexities of living processes, there is no room for any +other influence in the production of change, even of the most trivial +and apparently unmeaning kind. But if there were any good evidence or +logical argument to the contrary, this antecedent presumption would have +to give way; and the certainty that all specific characters are likewise +adaptive characters would be determined by the cogency of such evidence +or argument as could be adduced. In short, we are not entitled to +conclude--and still less does it follow "as a necessary deduction from +the theory of natural selection"--that all the details of specific +differentiation must in every case be either useful, vestigial, or +correlated, _unless it has been previously shown, by independent +evidence, or accurate reasoning, that there is no room for any other +principle of specific change_. + +This, apparently, is the central core of the question. Therefore I will +now proceed to consider such arguments as have been adduced to prove +that, other than natural selection, there _can_ have been no "means of +modification." And, after having exhibited the worthlessness of these +arguments, I will devote the next chapter to showing that, as a matter +of observable fact, there _are_ a considerable number of other +principles, which can be proved to be capable of producing such minute +differences of form and colour as "in a large proportional number" of +cases constitute diagnostic distinctions between species and species. + +First, then, for the reasons _a priori_--and they are confessedly _a +priori_--which have been adduced to prove that natural selection has +been what in Darwin's opinion it has not been,--"the _exclusive_ means +of modification." Disregarding the Lamarckian factors--which, even if +valid, have but little relation to the present question, seeing that +they are concerned, almost exclusively, with the evolution of _adaptive_ +characters--it is alleged that natural selection must occupy the whole +field, because no other principle of change can be allowed to operate in +the presence of natural selection. Now, I fully agree that this +statement may hold as regards any principle of change which is +deleterious; but clearly it does not hold as regards any principle which +is merely neutral. If any one were to allege that specific characters +are frequently detrimental to the species presenting them, he would no +doubt lay himself open to the retort that natural selection could not +allow such characters to persist; or, which amounts to the same thing, +that it _does_ "necessarily follow from the theory of natural selection" +that specific characters can never be in any large number, or in any +large measure, _harmful_ to the species presenting them. But where +the statement is that specific characters are frequently +_indifferent_--again to use Professor Huxley's term--the retort loses +all its relevancy. No reason has ever been shown why natural selection +should interfere with merely indifferent characters, supposing such to +have been produced by any of the agencies which we shall presently have +to consider. Therefore this argument--or rather assertion--goes for +nothing. + +The only other argument I have met with on this side of the question is +one that has recently been adduced by Mr. Wallace. He says:-- + + "One very weighty objection to the theory that _specific_ + characters can ever be wholly useless appears to have been + overlooked by those who have maintained the frequency of such + characters, and that is, their almost necessary instability[94]." + + [94] _Darwinism_, p. 138. + +This argument he proceeds to elaborate at considerable length, but fails +to perceive what appears to me the obvious answer. Provided that the +cause of the useless character is constant, there is no difficulty in +understanding why the character is stable. Utility is not the only +principle that can lead to stability: any other principle must do the +same, provided that it acts for a sufficient length of time, and with a +sufficient degree of uniformity, on all the individuals of a species. +This is a consideration the cogency of which was clearly recognized by +Darwin, as the following quotations will show. Speaking of unadaptive +characters, he says they may arise as merely + + "fluctuating variations, which sooner or later become _constant_ + through the nature of the organism and of surrounding conditions, + _but not through natural selection_[95]." + + [95] _Origin of Species_, p. 176: italics mine, as also in the + following. + +Elsewhere we read:-- + + "Each of the endless variations which we see in the plumage of our + fowls must have had some efficient cause; and if the _same_ cause + were to act _uniformly_ during a long series of generations on + _many_ individuals, _all_ probably would be modified in the same + manner." + +As special illustrations of this fact I may quote the following cases +from Darwin's works. + + "Dr. Bachman states that he has seen turkeys raised from the eggs + of wild species, lose their metallic tints, and become spotted in + the third generation. Mr. Yarrell many years ago informed me that + the wild ducks bred in St James' Park lost their true plumage + after a few generations. An excellent observer (Mr. Hewitt) ... + found that he could not breed wild ducks true for more than five or + six generations, as they proved so much less beautiful. The white + collar round the neck of the mallard became broader and more + irregular, and white feathers appeared in the duckling's wings + &c.[96]" + + [96] _Var._ vol. ii. p. 250. + +Now, such cases--to which numberless others might be added--prove that +even the subtle and inconspicuous causes incidental to domestication are +capable of inducing changes of specific character quite as great, and +quite as "stable," as any that in a state of nature are taken to +constitute specific distinctions. Yet there can here be no suggestion of +utility, inasmuch as the change takes place in the course of a few +generations, and therefore without leaving time for natural selection to +come into play--even if it ever could come into play among the sundry +domesticated birds in question. + +But the facts of domestication also make for the same conclusion in +another way--namely, by proving that when time enough _has_ been allowed +for the production of useless changes of greater magnitude, such changes +are not infrequently produced. And the value of this line of evidence is +that, great as are the changes, it is impossible that either natural or +artificial selection can have been concerned in their production. It +will be sufficient to give two examples--both with regard to structure. + +The first I will render in the words whereby it has already been stated +in my own paper on _Physiological Selection_, because I should like to +take this opportunity of answering Mr. Wallace's objection to it. + + "Elsewhere (_Origin of Species_, p. 158) Mr. Darwin points out that + modifications which appear to present obvious utility are often + found on further examination to be really useless. This latter + consideration, therefore, may be said to act as a foil to the one + against which I am arguing, namely, that modifications which appear + to be useless may nevertheless be useful. But here is a still more + suggestive consideration, also derived from Mr. Darwin's writings. + Among our domesticated productions changes of structure--or even + structures wholly new--not unfrequently arise, which are in every + way analogous to the apparently useless distinctions between wild + species. Take, for example, the following most instructive case:-- + + [Illustration: Fig. 2.--Old Irish Pig, showing jaw-appendages + (after Richardson).] + + "'Another curious anomaly is offered by the appendages described by + M. Eudes-Deslongchamps as often characterizing the Normandy pigs. + These appendages are always attached to the same spot, to the + corners of the jaws; they are cylindrical, about three inches in + length, covered with bristles, and with a pencil of bristles rising + out of a sinus on one side; they have a cartilaginous centre with + two small longitudinal muscles; they occur either symmetrically on + both sides of the face, or on one side alone. Richardson figures + them on the gaunt old Irish Greyhound pig; and Nathusius states + that they occasionally appear in all the long-eared races, but are + not strictly inherited, for they occur or fail in the animals of + the same litter. As no wild pigs are known to have analogous + appendages, we have at present no reason to suppose that their + appearance is due to reversion; and if this be so, we are forced to + admit that a somewhat complex, though apparently useless, structure + may be suddenly developed without the aid of selection[97].'" + + [97] _Variation_, &c. vol. i. pp. 78-79. + +To this case Mr. Wallace objects:-- + + "But it is expressly stated that they are not constant; they appear + 'frequently' or 'occasionally,' they are 'not strictly inherited, + for they occur or fail in animals of the same litter'; and they are + not always symmetrical, sometimes appearing on one side of the face + alone. Now, whatever may be the cause or explanation of these + anomalous appendages, they cannot be classed with 'specific + characters,' the most essential features of which are, that they + _are_ symmetrical, that they _are_ inherited, and that they _are_ + constant[98]." + + [98] _Darwinism_, pp. 139-40. + +But, to begin with, I have not classed these appendages with "specific +characters," nor maintained that Normandy pigs ought to be regarded as +specifically distinct on account of them. What I said was:-- + + "Now, if any such structure as this occurred in a wild species, and + if any one were to ask what is the use of it, those who rely on the + argument from ignorance would have a much stronger case than they + usually have; for they might point to the cartilage supplied with + muscles, and supporting a curious arrangement of bristles, as much + too specialized a structure to be wholly meaningless. Yet we happen + to know that this particular structure is wholly meaningless[99]." + + [99] Mr. Wallace deems the concluding words "rather confident." I + was not, however, before aware that he extended his _a priori_ + views on utility to domesticated varieties which are bred for + the slaughter-house. If he now means to indicate that these + appendages are possibly due to natural selection, he is surely + going very far to save his _a priori_ dogma; and in the case + next adduced will have to go further still. + +In the next place, is it either fair or reasonable to expect that a +varietal character of presumably very recent origin should be as +strongly inherited--and therefore as constant both in occurrence and +symmetry--as a true specific character, say, of a thousand times its +age? Even characters of so-called "constant varieties" in a state of +nature are usually less constant than specific characters; while, again, +as Darwin says, "it is notorious that specific characters are more +variable than generic,"--the reason in both cases being, as he proceeds +to show, that the less constant characters are characters of more recent +origin, and therefore less firmly fixed by heredity[100]. Hence I do not +understand how Mr. Wallace can conclude, as he does, "that, admitting +that this peculiar appendage is wholly useless and meaningless, the fact +would be rather an argument against specific characters being also +meaningless, because the latter never have the characteristics [i.e. +inconstancy of occurrence, form, and transmission] which this particular +variation possesses[101]." Mr. Wallace can scarcely suppose that when +specific characters first arise, they present the three-fold kind of +constancy to which he here alludes. But, if not, can it be denied that +these peculiar appendages appear to be passing through a phase of +development which all "specific characters" must have passed through, +before they have had time enough to be firmly fixed by heredity[102]? + + [100] _Origin of Species_, pp. 122-3. + + [101] _Darwinism_, p. 140. + + [102] In the next paragraph Mr. Wallace says that the appendages in + question "are apparently of the same nature as the 'sports' + that arise in our domesticated productions, but which, as Mr. + Darwin says, without the aid of selection would soon + disappear." But I cannot find that Mr. Darwin has made any + such statement: what he does say is, that whether or not a + useless peculiarity will soon disappear without the aid of + selection depends upon the nature of the causes which produce + it. If these causes are of a merely transitory nature, the + peculiarity will also be transitory; but if the causes be + constant, so will be the result. Again, the point to be + noticed about this "sport" is, that, unlike what is usually + understood by a "sport," it affects a whole race or breed, is + transmitted by sexual propagation, and has already attained so + definite a size and structure, that it can only be reasonably + accounted for by supposing the continued operation of _some + constant_ cause. This cause can scarcely be correlation of + growth, since closely similar appendages are often seen in so + different an animal as a goat. Here, also, they run in breeds + or strains, are strongly inherited, and more "constant," as + well as more "symmetrical" than they are in pigs. This, at all + events, is the account I have received of them from + goat-breeders in Switzerland. + +If, however, even this should be denied, what will be said of the second +case, that of the niata cattle? + + "I saw two herds on the northern bank of the Plata.... The forehead + is very short and broad, with the nasal end of the skull, together + with the whole plane of the upper molar-teeth, curved upwards. The + lower jaw projects beyond the upper, and has a corresponding upward + curvature.... The skull which I presented to the College of + Surgeons has been thus described by Professor Owen. 'It is + remarkable from the stunted development of the nasals, + premaxillaries, and fore part of the lower jaw, which is unusually + curved upwards to come into contact with the premaxillaries. The + nasal bones are about one-third the ordinary length, but retain + almost their normal breadth. The triangular vacuity is left between + them and the frontal and lachrymal, which latter bone articulates + with the premaxillary, and thus excludes the maxillary from any + junction with the nasal.' So that even the connexion of some of + the bones is changed. Other differences might be added: thus the + plane of the condyles is somewhat modified, and the terminal edge + of the premaxillaries forms an arch. In fact, on comparison with + the skull of a common ox, scarcely a single bone presents the same + exact shape, and the whole skull has a wonderfully different + appearance[103]." + + [103] Darwin, _Variation_, &c., vol. i. pp. 92-4. + +[Illustration: Fig. 3.--Drawn from nature. R. Coll. Surg. Mus.] + +As I cannot find that this remarkable skull has been figured before, I +have had the accompanying woodcut made in order to compare it with the +skull of a Charsley Forest ox; and a glance is sufficient to show what +"a wonderfully different appearance" it presents. + + * * * * * + +Now the important points in the present connexion with regard to this +peculiar race of cattle are the following. + +Their origin is not known; but it must have been subsequent to the year +1552, when cattle were first introduced to America from Europe, and it +is known that such cattle have been in existence for at least a century. +The breed is very true, and a niata bull and cow invariably produce +niata calves. A niata bull crossed with a common cow, and the reverse +cross, yield offspring having an intermediate character, but with the +niata peculiarities highly conspicuous[104]. + + [104] _Ibid._ p. 94. + +Here, then, we have unquestionable evidence of a whole congeries of very +distinctive characters, so unlike anything that occurs in any other +cattle, that, had they been found in a state of nature, they would have +been regarded as a distinct species. And the highly peculiar characters +which they present conform to all "the most essential features of +specific characters," as these are stated by Mr. Wallace in his +objection to the case of the pig's appendages. That is to say, "they +_are_ symmetrical, they _are_ inherited, and they _are_ constant." In +point of fact, they are _always_ "constant," both as to occurrence and +symmetry, while they are so completely "inherited" that not only does "a +niata bull and cow _invariably_ produce niata calves"; but even when +crossed with other cattle the result is a _hybrid_, "with the niata +character _strongly_ displayed." + +Hence, if we were to follow Mr. Wallace's criteria of specific +characters, which show that the pig's appendages "cannot be classed with +specific characters" (or with anything of the nature of specific +characters), it would follow that the niata peculiarities _can_ be so +classed. This, therefore, is a case where he will find all the reasons +which in other cases he takes to justify him in falling back upon the +argument from ignorance. The cattle are half wild, he may urge; and so +the three-fold constancy of their peculiar characters may very well be +due, either directly or indirectly, to natural selection--i.e. they may +either be of some hidden use themselves, or correlated with some other +modifications that are of use: it is, he may say, as in such cases he +often does say, for us to disprove both these possibilities. + +Well, here we have one of those rare cases where historical information, +or other accidents, admit of our discharging this burden of proving a +negative. Darwin's further description shows that this customary refuge +in the argument from ignorance is most effectually closed. For-- + + "When the pasture is tolerably long, these cattle feed as well as + common cattle with their tongue and palate; but during the great + droughts, when so many animals perish on the Pampas, the niata + breed lies under a great disadvantage, and would, if not attended + to, become extinct; for the common cattle, like horses, are able to + keep alive by browsing with their lips on the twigs of trees and on + reeds; this the niatas cannot so well do, as their lips do not + join, and hence they are found to perish before the common cattle. + This strikes me as a good illustration of how little we are able to + judge from the ordinary habits of an animal, on what circumstances, + occurring only at long intervals of time, its rarity or extinction + may depend. It shows us, also, how natural selection would have + determined the rejection of the niata modification, had it arisen + in a state of nature[105]." + + [105] Darwin, _Variation_, &c. vol. i. p. 94. + +Hence, it is plainly _impossible_ to attribute this modification to +natural selection, either as acting directly on the modified parts +themselves, or indirectly through correlation of growth. And as the +modification is of specific magnitude on the one hand, while it presents +all "the most essential features of specific characters" on the other, I +do not see any means whereby Mr. Wallace can meet it on his _a priori_ +principles. It would be useless to answer that these characters, +although conforming to all his tests of specific characters, differ in +respect of being deleterious, and would therefore lead to extermination +were the animals in a wholly wild state; because, considered as an +argument, this would involve the assumption that, apart from natural +selection, only deleterious characters can arise under nature--i. e. +that merely "indifferent" characters can never do so, which would be +absurd. Indeed, I have chosen this case of the niata cattle expressly +because their strongly marked peculiarities _are_ deleterious, and +therefore exclude Mr. Wallace's appeal to the argument from ignorance of +a possible utility. But if even these pronounced and deleterious +peculiarities can arise and be perpetuated with such constancy and +fidelity, much more is this likely to be the case with less pronounced +and merely neutral peculiarities. + +It may, however, be further objected that these cattle are not +improbably the result of _artificial_ selection. It may be suggested +that the semi-monstrous breed originated in a single congenital +variation, or "sport," which was isolated and multiplied as a curiosity +by the early settlers. But even if such be the explanation of this +particular case, the fact would not weaken our illustration. On the +contrary, it would strengthen our general argument, by showing an +additional means whereby indifferent specific characters can arise and +become fixed in a state of nature. As it seems to me extremely probable +that the niata cattle did originate in a congenital monstrosity, which +was then isolated and multiplied by human agency (as is known to have +been the case with the "ancon sheep"), I will explain why this tends to +strengthen our general argument. + +It is certain that if these animals were ever subject to artificial +isolation for the purpose of establishing their breed, the process must +have ceased a long time ago, seeing that there is no memory or tradition +of its occurrence. Now this proves that, however the breed may have +originated, it has been able to maintain its many and highly peculiar +characters for a number of generations without the help of selection, +either natural or artificial. This is the first point to be clear upon. +Be its origin what it may, we know that this breed has proved capable of +perpetuating itself with uniform "constancy" for a number of generations +after the artificial selection has ceased--supposing such a process ever +to have occurred. And this certain fact that artificial selection, even +if it was originally needed to establish the type, has not been needed +to perpetuate the type, is a full answer to the supposed objection. For, +in view of this fact, it is immaterial what the origin of the niata +breed may have been. In the present connexion, the importance of this +breed consists in its proving the subsequent "stability" of an almost +monstrous form, continued through a long series of generations by the +force of heredity alone, without the aid of any form of selection. + +The next point is, that not only is a seeming objection to the +illustration thus removed, but that, if we do entertain the question of +origin, and if we do suppose the origin of these cattle to have been in +a congenital "sport," afterwards multiplied by artificial isolation, we +actually strengthen our general argument by increasing the importance of +this particular illustration. For the illustration then becomes +available to show how indifferent specific characters may sometimes +originate in merely individual sports, which, if not immediately +extinguished by free intercrossing, will perpetuate themselves by the +unaided force of heredity. But this is a point to which we shall recur +in the ensuing chapter. + +In conclusion, it is worth while to remark, with regard to Mr. Wallace's +argument from constancy, that, as a matter of fact, utility does not +seem to present any greater power in securing "stability of characters" +than any other cause of like constancy. Thus, for instance, whatever the +causes may have been which have produced and perpetuated the niata breed +of cattle, they have certainly produced a wonderful "stability" of a +great modification in a wonderfully short time. And the same has to be +said of the ducks in St. James' Park, as well as sundry other cases. On +the other hand, when, as in the case of numberless natural species, +modification has been undoubtedly produced by natural selection, +although the modification must have had a very much longer time in which +to have been fixed by heredity, it is often far from being +stable--notwithstanding that Mr. Wallace regards stability as a +criterion of specific characters. Indeed--and this is more suggestive +still--there even seems to be a kind of _inverse_ proportion between the +utility and the stability of a specific character. The explanation +appears to be (_Origin of Species_, pp. 120-2), that the more a specific +character has been forced on by natural selection on account of its +utility, the less time will it have had to become well fixed by heredity +before attaining a full development. Moreover, as Darwin adds, in cases +where the modification has not only been thus "comparatively recent," +but also "extraordinarily great," the probability is that the parts so +modified must have been very variable in the first instance, and so are +all the more difficult to render constant by heredity. Thus we see that +utility is no better--even if it be so good--a cause of stability in +specific characters, as are the unknown causes of stability in many +varietal characters[106]. + + [106] Should it be objected that useless characters, according to my + own view of the Cessation of Selection, ought to disappear, + and therefore cannot be constant, the answer is evident. For, + by hypothesis, it is only those useless characters which were + at one time useful that disappear under this principle. + Selection cannot cease unless it was previously present--i.e. + save in cases where the now useless character was originally + due to selection. Hence, in all cases where it was due to any + other cause, the useless character will persist at least as + long as its originating cause continues to operate. And even + after the latter (whatever it may be) has ceased to operate, + the useless character will but slowly degenerate, until the + eventual failure of heredity causes it to disappear _in + toto_--long before which time it may very well have become a + genetic, or some higher, character. + + + + +CHAPTER VIII. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_continued_). + + +Let us now proceed to indicate some of the causes, other than natural +selection, which may be regarded as adequate to induce such changes in +organic types as are taken by systematists to constitute diagnostic +distinctions between species and species. We will first consider causes +external to organisms, and will then go on to consider those which occur +within the organisms themselves: following, in fact, the classification +which Darwin has himself laid down. For he constantly speaks of such +causes as arising on the one hand, from "changed conditions of life" +and, on the other hand, from "the nature of the organism"--that is, from +internal processes leading to "variations which seem to us in our +ignorance to arise spontaneously." + +In neither case will it be practicable to give more than a brief +_résumé_ of all that might be said on these interesting topics. + + +I. _Climate._ + +There is an overwhelming mass of evidence to prove that the assemblage +of external conditions of life conveniently summarized in the word +Climate, exercise a potent, an uniform, and a permanent influence on +specific characters. + +With regard to plants, Darwin adduces a number of facts to show the +effects of climate on wheat, cabbages, and other vegetables. Here, for +example, is what he says with regard to maize imported from America to +Germany:-- + + "During the first year the plants were twelve feet high, and a few + seeds were perfected; the lower seeds in the ear kept true to their + proper form, but the upper seeds became slightly changed. In the + second generation the plants were from nine to ten feet high, and + ripened their seed better; the depression on the outer side of the + seed had almost disappeared, and the original beautiful white + colour had become duskier. Some of the seeds had even become + yellow, and in their now rounded form they approached the common + European maize. In the third generation nearly all resemblance to + the original and very distinct American parent-form was lost[107]." + + [107] _Variation_, &c. vol. i. p. 340. + +As these "highly remarkable" changes were effected in but three +generations, it is obvious that they cannot have been dependent on +selection of any kind. The same remark applies to trees. Thus,-- + + "Mr. Meehan has compared twenty-nine kinds of American trees with + their nearest European allies, all grown in close proximity and + under as nearly as possible the same conditions. In the American + species he finds, with the rarest exceptions, that the leaves fall + earlier in the season, and assume before their fall a brighter + tint; that they are less deeply toothed or serrated; that the buds + are smaller; that the trees are more diffuse in growth and have + fewer branchlets; and, lastly, that the seeds are smaller--all in + comparison with the corresponding European species. Now, + considering that these corresponding trees belong to several + distinct orders, and that they are adapted to widely different + stations, it can hardly be supposed that their differences are of + any special service to them in the New and Old worlds; and, if so, + such differences cannot have been gained through natural selection, + and must be attributed to the long continued action of a different + climate[108]." + + [108] _Variation_, &c. vol. ii. p. 271. + +These cases, however, I quote mainly in order to show Darwin's opinion +upon the matter, with reference to the absence of natural selection. +For, where the vegetable kingdom is concerned, the fact of climatic +variation is so general, and in its relation to diagnostic work so +important, that it constitutes one of the chief difficulties against +which species-makers have to contend. And the more carefully the subject +is examined the greater does the difficulty become. But, as to this and +other general facts, it will be best to allow a recognized authority to +speak; and therefore I will give a few extracts from Kerner's work on +_Gute und schlechte Arten_. + +He begins by showing that geographical (or it may be topographical) +varieties of species are often so divergent, that without a knowledge of +intermediate forms there could be no question as to their being good +species. As a result of his own researches on the subject, he can +scarcely find language strong enough to express his estimate of the +extent and the generality of this source of error. In different parts of +Europe, or even in different parts of the Alps, he has found these +climatic varieties in such multitudes and in such high degrees both of +constancy and divergence, that, after detailing his results, he +finishes his essay with the following remarkable conclusions:-- + + "Die Wissenchaft geht aber ihren Entwicklungsgang im grossen Ganzen + gerade so, wie die Erkenntniss bei jedem einzelnen Naturforscher. + Fast jeder Botaniker muss seinen Entwicklungsgang durchmachen und + gelangt endlich mehr oder weniger nahe zu demselben Ziele. Die + Ungleichheit besteht nur darin, dass der eine langsamer, der andere + aber rascher bei dem Ziele ankommt. Anfänglich müht sich jeder ab, + die Formen in hergebrachter Weise zu gliedern und die 'guten Arten' + herauszulesen. Mit der Erweiterung des Gesichtskreises und mit der + Vermehrung der Anschauungen aber schwindet auch immer mehr der + Boden unter den Füssen, die bisher für unverrückbar gehaltenen + Grenzen der gut geglaubten Arten stellen sich als eine der Natur + angelegte Zwangsjacke heraus, die Uebcrzeugung, dass die Grenzen, + welche wir ziehen, eben nur künstliche sind, gewinnt immer mehr und + mehr die Oberhand, und wer nicht gerade zu den hartgesottenen + Eigensinnigen gehört, und wer die Wahrheit höher stellt als das + starre Festhalten an seinen früheren Ansichten, geht schliesslich + bewusst oder unbewusst in das Lager derjenigen über, in welchem + auch ich mir ein bescheidenes Plätzchen aufgesucht habe." + +By these "hard-boiled" botanists he means those who entertain the +traditional notion of a species as an assemblage of definite +characters, always and everywhere associated together. This notion +(Artsbeständigkeit) must be entirely abandoned. Summarizing Kerner's +facts for their general results we find that his extensive +investigations have proved that in his numberless kinds of European +plants the following relations frequently obtain. Supposing that there +are two or more allied species, A and B, then A' and B' may be taken to +represent their respective types as found in some particular area. It +does not signify whether A' and B' are geographically remote from, or +close to, A and B; the point is that, whether in respect of temperature, +altitude, moisture, character of soil, &c., there is some difference in +the conditions of life experienced by the plants growing at the +different places. Now, in numberless plants it is found that the typical +or constant peculiarities of A' differ more from those of A than they do +from those of B; while, conversely, the characters of A' may bear more +resemblance to those of B' than they do to those of A--on account of +such characters being due to the same external causes in both cases. The +consequence is that A' might more correctly be classified with B', or +_vice versa_. Another consequence is that whether A and B, or A' and B', +be recorded as the "good species" usually depends upon which has +happened to have been first described. + +Such a mere abstract of Kerner's general results, however, can give no +adequate idea of their cogency: for this arises from the number of +species in which specific characters are thus found to change, and even +to _interchange_, with different conditions of life. Thus he gives an +amusing parable of an ardent young botanist, Simplicius, who starts on a +tour in the Tyrol with the works of the most authoritative systematists +to assist him in his study of the flora. The result is that Simplicius +becomes so hopelessly bewildered in his attempts at squaring their +diagnostic descriptions with the facts of nature, that he can only +exclaim in despair--"Sonderbare Flora, diese tirolische, in welcher so +viele characteristische Pflanzen nur schlechte Arten, oder gar noch +schlechter als schlechte Arten, sind." Now, in giving illustrations of +this young man's troubles, Kerner fills five or six pages with little +else than rows of specific names. + +Upon the whole, Kerner concludes that the more the subject is studied, +the more convinced must the student become that all distinction between +species as "good" and "bad" vanishes. In other words, the more that our +knowledge of species and of their diagnostic characters increases, the +more do we find that "bad species" multiply at the expense of "good +species"; so that eventually we must relinquish the idea of "good +species" altogether. Or, conversely stated, we must agree to regard as +equally "good species" any and every assemblage of individuals which +present the same peculiarities: provided that these peculiarities do not +rise to a generic value, they equally deserve to be regarded as +"specific characters," no matter how trivial, or how local, they may be. +In fact, he goes so far as to say that when, as a result of experiments +in transplantation from one set of physical conditions to another, +seedlings are found to present any considerable and constant change in +their specific characters, these seedlings are no less entitled to be +regarded as a "good species" than are the plants from which they have +been derived. Probably few systematists will consent to go quite so far +as this; but the fact that Kerner has been led deliberately to propound +such a statement as a result of his wide observations and experiments is +about as good evidence as possible on the points with which we are here +concerned. For even Simplicius would hardly be quite so simple as to +suppose that each one of all the characters which he observes in his +"remarkable flora," so largely composed of "bad or even worse than bad +species," is of utilitarian significance. + +Be it noted, however, that I am not now expressing my own opinion. There +are weighty reasons against thus identifying climatic variations with +good species--reasons which will be dealt with in the next chapter. +Kerner does not seem to appreciate the weight of these reasons, and +therefore I do not call him as a witness to the subject as a whole; but +only to that part of it which has to do with the great and general +importance of climatic variability in relation to diagnostic work. And +thus far his testimony is fully corroborated by every other botanist who +has ever attended to the subject. Therefore it does not seem worth while +to quote further authorities in substantiation of this point, such as +Gärtner, De Candolle, Nägeli, Peter, Jordan, &c. For nowadays no one +will dispute the high generality and the frequently great extent of +climatic variation where the vegetable kingdom is concerned. Indeed, it +may fairly be doubted whether there is any one species of plant, whose +distribution exposes it to any considerable differences in its external +conditions of life, which does not present more or less considerable +differences as to its characters in different parts of its range. The +principal causes of such climatic variation appear to be the chemical, +and, still more, the mechanical nature of soil; temperature; intensity +and diurnal duration of light in spring and summer; moisture; presence +of certain salts in the air and soil of marine plants, or of plants +growing near mineral springs; and sundry other circumstances of a more +or less unknown character. + +Before closing these remarks on climatic variation in the vegetable +kingdom, prominent attention must be directed to a fact of broad +generality and, in relation to our present subject, of considerable +importance. This is that the same external causes very frequently +produce the same effects in the way of specific change throughout large +numbers of _unrelated_ species--i.e. species belonging to different +genera, families, and orders. Moreover, throughout all these unrelated +species, we can frequently trace a uniform correlation between the +degrees of change and the degrees to which they have been subjected to +the causes in question. + +As examples, all botanists who have attended to the subject are struck +by the similarity of variation presented by different species growing on +the same soils, altitudes, latitudes, longitudes, and so forth. Plants +growing on chalky soils, when compared with those growing on richer +soils, are often more thickly covered with down, which is usually of a +white or grey colour. Their leaves are frequently of a bluish-green +tint, more deeply cut, and less veined, while their flowers tend to be +larger and of a lighter tint. There are similarly constant differences +in other respects in varieties growing on sundry other kinds of soils. +Sea-salt has the general effect, on many different kinds of plants, of +producing moist fleshy leaves, and red tints. Experiments in +transplantation have shown that these changes may be induced +artificially; so there can be no doubt as to its being this that and the +other set of external conditions which produces them in nature. Again, +dampness causes leaves to become smoother, greener, less cut, and the +flowers to become darker; while dryness tends to produce opposite +effects. I need not go on to specify the particular results on all kinds +of plants of altitude, latitude, longitude, and so forth. For we are +concerned only with the fact that these two correlations may be regarded +as general laws appertaining to the vegetable kingdom--namely, (A) that +the same external causes produce similar varietal effects in numerous +unallied species of plants; and, (B) that the more these species are +exposed to such causes the greater is the amount of varietal effect +produced--so that, for instance, on travelling from latitude to +latitude, longitude to longitude, altitude to altitude, &c., we may see +greater and greater degrees of such definite and more or less common +varietal changes affecting the unallied species in question. Now these +general laws are of importance for us, because they prove unequivocally +that it is the direct action of external conditions of life which +produce climatic variations of specific types. And, taken in connexion +with the results of experiments in transplantation (which in a single +generation may yield variations similar to those found in nature under +similar circumstances), these general laws still further indicate that +climatic variations are "indifferent" variations. In other words, we +find that changes of specific characters are of widespread occurrence in +the vegetable kingdom, that they are constantly and even proportionally +related to definite external circumstances, but yet that, in as far as +they are climatic, they cannot be attributed to the agency of natural +selection[109]. + + [109] Since the above paragraphs have been in type, the Rev. G. + Henslow has published his Linnaean Society papers which are + mentioned in the introductory chapter, and which deal in more + detail with this subject, especially as regards the facies of + desert floras. + +Turning next to animals, it may first be observed that climatic +conditions do not appear to exercise an influence either so general or +so considerable as in the case of plants. Nevertheless, although these +influences are relatively more effective in the vegetable kingdom than +they are in the animal, absolutely considered they are of high +generality and great importance even in the latter. But as this fact is +so well recognized by all zoologists, it will be needless to give more +than a very few illustrations. Indeed, throughout this discussion on +climatic influences my aim is merely to give the general reader some +idea of their importance in regard to systematic natural history; and, +therefore, such particular cases as are mentioned are selected only as +samples of whole groups of cases more or less similar. + +With regard to animals, then, we may best begin by noticing that, just +as in the case of plants, there is good evidence of the same external +causes producing the same effects in multitudes of species belonging to +different genera, families, orders, and even classes. Moreover, we are +not without similarly good evidence of _degrees_ of specific change +taking place in correlation with _degrees_ of climatic change, so that +we may frequently trace a gradual progress of the former as we advance, +say, from one part of a large continent to another. Instances of these +correlations are not indeed so numerous in the animal kingdom as they +are in the vegetable. Nevertheless they are amply sufficient for our +present purposes. + +For example, Mr. Allen has studied in detail changes of size and colour +among birds and mammals on the American continent; and he finds a +wonderfully close sliding scale of both, corresponding stage by stage +with gradual changes of climate. Very reasonably he attributes this to +the direct influence of climatic conditions, without reference to +natural selection--as does also Mr. Gould with reference to similar +facts which he has observed among the birds of Australia. Against this +view Mr. Wallace urges, "that the effects are due to the greater or less +need of protection." But it is difficult to believe that such can be the +case where so innumerable a multitude of widely different species are +concerned--presenting so many diverse habits, as well as so many +distinct habitats. Moreover, the explanation seems incompatible with the +_graduated_ nature of the change, and also with the fact that not only +colouration but size, is implicated. + +We meet with analogous facts in butterflies. Thus _Lycaena agestis_ not +only presents seasonal variations, (A) and (B); but while (A) and (B) +are respectively the winter and summer forms in Germany, (B) and (C) are +the corresponding forms in Italy. Therefore, (B) is in Germany the +summer form, and in Italy the winter form--the German winter form (A) +being absent in Italy, while the Italian summer form (C) is absent in +Germany. Probably these facts are due to differences of temperature in +the two countries, for experiments have shown that when pupae of sundry +species of moths and butterflies are exposed to different degrees of +temperature, the most wonderful changes of colour may result in the +insects which emerge. The remarkable experiments of Dorfmeister and +Weismann in relation to this subject are well known. More recently Mr. +Merrifield has added to their facts, and concludes that the action of +cold upon the pupae--and also, apparently, upon the larvae--has a +tendency to produce dark hues in the perfect insect[110]. + + [110] _Trans. Entom. Soc._ 1889, part i. p. 79 _et seq._ + +But, passing now from such facts of climatic variations over wide areas +to similar facts within small areas, in an important _Memoir on the Cave +Fauna of North America_, published a few years ago by the American +Academy of Sciences, it is stated:-- + + "As regards change of colour, we do not recall an exception to the + general rule that all cave animals are either colourless or nearly + white, or, as in the case of Arachnida and Insects, much paler than + their out-of-door relatives." + +Now, when we remember that these cave faunas comprise representatives of +nearly all classes of the animal kingdom, it becomes difficult, if not +impossible, to imagine that so universal a discharge of colouring can be +due to natural selection. It must be admitted that the only way in which +natural selection could act in this case would be indirectly through the +principle of correlation. There being no light in the caves, it can be +of no advantage to the animals concerned that they should lose their +colour for the sake of protection, or for any other reason of a +similarly direct kind. Therefore, if the loss of colour is to be +ascribed to natural selection, this can only be done by supposing that +natural selection has here acted indirectly through the principle of +correlation. There is evidence to show that elsewhere modification or +loss of colour is in some cases brought about by natural selection, on +account of the original colour being correlated with certain +physiological characters (such as liability to particular diseases, +&c.); so that when natural selection operates directly upon these +physiological characters, it thereby also operates indirectly upon the +correlated colours. But to suppose that this can be the explanation of +the uniform diminution of colour in all inhabitants of dark caves would +be manifestly absurd. If there were only one class of animals in these +caves, such as Insects, it might be possible to surmise that their +change of colour is due to natural selection acting directly upon their +physiological constitutions, and so indirectly upon their colours. But +it would be absurd to suppose that such can be the explanation of the +facts, when these extend in so similar a manner over so many scores of +species belonging to such different types of animal life. + +With more plausibility it might be held that the universal discharge of +colour in these cave-faunas is due, not to the presence, but to the +absence of selection--i. e. to the cessation of selection, or panmixia. +But against this--at all events as a full or general explanation--lie +the following facts. First, in the case of Proteus--which has often been +kept for the purposes of exhibition &c., in tanks--the skin becomes dark +when the animal is removed from the cave and kept in the light. +Secondly, deep-sea faunas, though as much exposed as the cave-faunas, to +the condition of darkness, are not by any means invariably colourless. +On the contrary, they frequently present brilliant colouration. Thus it +is evident that if panmixia be suggested in explanation of the +discharge of colouring in cave-faunas, the continuance of colour in +deep-sea faunas appears to show the explanation insufficient. Thirdly, +according to my view of the action of panmixia as previously explained, +no _total_ discharge of colouration is likely to be caused by such +action alone. At most the bleaching as a result of the mere withdrawal +of selection would proceed only to some comparatively small extent. +Fourthly, Mr. Packard in the elaborate _Memoir on Cave Fauna_, already +alluded to, states that in some of the cases the phenomena of bleaching +appear to have been induced within very recent times--if not, indeed, +within the limits of a single generation. Should the evidence in support +of this opinion prove trustworthy, of course in itself it disposes of +any suggestion either of the presence or the absence of natural +selection as concerned in the process. + +Nevertheless, I myself think it inevitable that to some extent the +cessation of selection must have helped in discharging the colour of +cave faunas; although for the reasons now given it appears to me that +the main causes of change must have been of that direct order which we +understand by the term climatic. + +As regards dogs, the Rev. E. Everest found it impossible to breed Scotch +setters in India true to their type. Even in the second generation no +single young dog resembled its parents either in form or shape. "Their +nostrils were more contracted, their noses more pointed, their size +inferior, and their limbs more slender[111]." Similarly on the coast of +New Guinea, Bosman says that imported breeds of dogs "alter strangely; +their ears grow long and stiff like those of foxes, to which colour they +also incline ... and in three or four broods their barking turns into a +howl[112]." + + [111] _Variation_, &c. vol. i. p. 40. + + [112] _Variation_, &c. vol. i. p. 40. + +Darwin gives numerous facts showing the effects of climate on horses, +cattle, and sheep, in altering, more or less considerably, the +characters of their ancestral stocks. He also gives the following +remarkable case with regard to the rabbit. Early in the fifteenth +century a common rabbit and her young ones were turned out on the island +of Porto Santo, near Madeira. The feral progeny now differ in many +respects from their parent stock. They are only about one-third of the +weight, present many differences in the relative sizes of different +parts, and have greatly changed in colour. In particular, the black on +the upper surface of the tail and tips of the ears, which is so constant +in all other wild rabbits of the world as to be given in most works as a +specific character, has entirely disappeared. Again, "the throat and +certain parts of the under surface, instead of being pure white, are +generally grey or leaden colour," while the upper surface of the whole +body is redder than in the common rabbit. Now, what answer have our +opponents to make to such a case as this? Presumably they will answer +that the case simply proves the action of natural selection during the +best part of 400 years on an isolated section of a species. Although we +cannot say of what use all these changes have been to the rabbits +presenting them, nevertheless we _must_ believe that they have been +produced by natural selection, and therefore _must_ present some hidden +use to the isolated colony of rabbits thus peculiarly situated. Four +centuries is long enough to admit of natural selection effecting all +these changes in the case of so rapidly breeding an animal as the +rabbit, and therefore it is needless to look further for any explanation +of the facts. Such, I say, is presumably the answer that would be given +by the upholders of natural selection as the only possible cause of +specific change. But now, in this particular case it so happens that the +answer admits of being conclusively negatived, by showing that the great +assumption on which it reposes is demonstrably false. For Darwin +examined two living specimens of these rabbits which had recently been +sent from Porto Santo to the Zoological Gardens, and found them coloured +as just described. Four years afterwards the dead body of one of them +was sent to him, and then he found that the following changes had taken +place. "The ears were plainly edged, and the upper surface of the tail +was covered with blackish-grey fur, and the whole body was much less +red; so that under the English climate this individual rabbit has +recovered the proper colour of its fur in rather less than four years!" + +Mr. Darwin adds:-- + + "If the history of these Porto Santo rabbits had not been known, + most naturalists, on observing their much reduced size, their + colour, reddish above and grey beneath, their tails and ears not + tipped with black, would have ranked them as a distinct species. + They would have been strongly confirmed in this view by seeing them + alive in the Zoological Gardens, and hearing that they refused to + couple with other rabbits. Yet this rabbit, which there can be + little doubt would thus have been ranked as a distinct species, as + certainly originated since the year 1420[113]." + + [113] _Variation_, &c. vol. i. p. 120. + +Moreover, it certainly originated as a direct result of climatic +influences, independent of natural selection; seeing that, as soon as +individual members of this apparently new species were restored to their +original climate, they recovered their original colouration. + +As previously remarked, it is, from the nature of the case, an +exceedingly difficult thing to prove in any given instance that natural +selection has not been the cause of specific change, and so finally to +disprove the assumption that it must have been. Here, however, on +account of historical information, we have a crucial test of the +validity of this assumption, just as we had in the case of the niata +cattle; and, just as in their case, the result is definitely and +conclusively to overturn the assumption. If these changes in the Porto +Santo rabbits had been due to the gradual influence of natural selection +guided by inscrutable utility, it is simply impossible that the same +individual animals, in the course of their own individual life-times, +should revert to the specific characters of their ancestral stock on +being returned to the conditions of their ancestral climate. Therefore, +unless any naturalist is prepared to contradict Darwin's statement that +the changes in question amount to changes of specific magnitude, he can +find no escape from the conclusion that distinctions of specific +importance may be brought about by changes of habitat alone, without +reference to utility, and therefore independently of natural selection. + + +II. _Food._ + +Although, as yet, little is definitely known on the subject, there can +be no doubt that in the case of many animals differences of food induce +differences of colour within the life-time of individuals, and therefore +independently of natural selection. + +Thus, sundry definite varieties of the butterfly _Euprepia caja_ can be +reared according to the different nourishment which is supplied to the +caterpillar; and other butterflies are also known on whose colouring and +markings the food of the caterpillar has great influence[114]. + + [114] See especially, Koch, _Die Raupen und Schmetterling der + Wetterau_, and _Die Schmetterling des Südwestlichen + Deutschlands_, whose very remarkable results of numerous and + varied experiments are epitomized by Eimer, _Organic + Evolution_, Eng. Trans. pp. 147-153; also Poulton, _Trans. + Entom. Soc._ 1893. + +Again, I may mention the remarkable case communicated to Darwin by +Moritz Wagner, of a species of _Saturnia_, some pupae of which were +transported from Texas to Switzerland in 1870. The moths which emerged +in the following year were like the normal type in Texas. Their young +were supplied with leaves of _Juglans regia_, instead of their natural +food, _J. nigra_; and the moths into which these caterpillars changed +were so different from their parents, both in form and colour, "that +they were reckoned by entomologists as a distinct species[115]." + + [115] Mivart, _On Truth_, p. 378. + +With regard to mollusks, M. Costa tells us that English oysters, when +turned down in the Mediterranean, "_rapidly_ became like the true +Mediterranean oyster, altered their manner of growth, and formed +prominent diverging rays." This is most probably due to some change of +food. So likewise may be the even more remarkable case of _Helix +nemoralis_, which was introduced from Europe to Virginia a few years +ago. Under the new conditions it varied to such an extent that up to +last year no less than 125 varieties had been discovered. Of these 67, +or more than half, are new--that is, unknown in the native continent of +the species[116]. + + [116] Cockerell, _Nature_, vol. xli. p. 393. + +In the case of Birds, the Brazilian parrot _Chrysotis festiva_ changes +the green in its feathers to red or yellow, if fed on the fat of certain +fishes; and the Indian Lori has its splendid colouring preserved by a +peculiar kind of food (Wallace). The Bullfinch is well known to turn +black when fed on hemp seeds, and the Canary to become red when fed on +cayenne pepper (Darwin). Starting from these facts, Dr. Sauermann has +recently investigated the subject experimentally; and finds that not +only finches, but likewise other birds, such as fowls, and pigeons, are +subject to similar variations of colour when fed on cayenne pepper; but +in all cases the effect is produced only if the pepper is given to the +young birds before their first moult. Moreover, he finds that a moist +atmosphere facilitates the change of colour, and that the ruddy hue is +discharged under the influence either of sunlight or of cold. Lastly, he +has observed that sundry other materials such as glycerine and aniline +dyes, produce the same results; so there can be no doubt that organic +compounds probably occur in nature which are capable of directly +affecting the colours of plumage when eaten by birds. Therefore the +presence of such materials in the food-stuffs of birds occupying +different areas may very well in many cases determine differences of +colouration, which are constant or stable so long as the conditions of +their production are maintained. + + +III. _Sexual Selection._ + +Passing on now to causes of specific change which are internal, or +comprised within the organisms themselves, we may first consider the +case of Sexual Selection. + +Mr. Wallace rejects the theory of sexual selection _in toto_, and +therefore nothing that can be said under this head would be held by him +to be relevant. Many naturalists, however, believe that Darwin was right +in the large generalization which he published under this title; and in +so far as any one holds that sexual selection is a true cause of +specific modification, he is obliged to believe that innumerable +specific characters--especially in birds and mammals--have been produced +without reference to utility (other, of course, than utility for sexual +purposes), and therefore without reference to natural selection. This is +so obvious that I need not pause to dilate upon it. One remark, however, +may be useful. Mr. Wallace is able to make a much more effective use of +his argument from "necessary instability" when he brings it against the +Darwinian doctrine of sexual selection, than he does when he brings it +against the equally Darwinian doctrine of specific characters in general +not being all necessarily due to natural selection. In the latter case, +it will be remembered, he is easily met by showing that the causes of +specific change other than natural selection, such as food, climate, +&c., may be quite as general, persistent, and uniform, as natural +selection itself; and therefore in this connexion Mr. Wallace's argument +falls to the ground. But the argument is much more formidable as he +brings it to bear against the theory of sexual selection. Here he asks, +What is there to guarantee the uniformity and the constancy of feminine +taste with regard to small matters of embellishment through thousands of +generations, and among animals living on extensive areas? And, as we +have seen in Part 1, it is not easy to supply an answer. Therefore this +argument from the "necessary instability of character" is of +immeasurably greater force as thus applied against Darwin's doctrine of +sexual selection, than it is when brought against his doctrine that all +specific characters need not necessarily be due to natural selection. +Therefore, also, if any one feels disposed to attach the smallest degree +of value to this argument in the latter case, consistency will require +him to allow that in the former case it is simply overwhelming, or in +itself destructive of the whole theory of sexual selection. And, +conversely, if his belief in the theory of sexual selection can survive +collision with this objection from instability, he ought not to feel any +tremor of contact when the objection is brought to bear against his +scepticism regarding the alleged utility of all specific characters. For +assuredly no specific character which is apparent to our eyes can be +supposed to be so refined and complex (and therefore so presumably +inconstant and unstable), as are those minute changes of cerebral +structure on which a psychological preference for all the refined +shadings and many pigments of a complicated pattern must be held +ultimately to depend. For this reason, then, as well as for those +previously adduced, if any one agrees with Darwin in holding to the +theory of sexual selection notwithstanding this objection from the +necessary instability of unuseful embellishments, _a fortiori_ he ought +to disregard the objection altogether in its relation to useless +specific characters of other kinds. + +But quite apart from this consideration, which Mr. Wallace and his +followers may very properly say does not apply to them, let us see what +they themselves have made of the facts of secondary sexual +characters--which, of course, are for the most part specific +characters--in relation to the doctrine of utility. + +Mr. Wallace himself, in his last work, quotes approvingly a letter which +he received in 1869 from the Rev. O Pickard-Cambridge, as follows:-- + + "I myself doubt that particular application of the Darwinian theory + which attributes male peculiarities of form, structure, colour, and + ornament to female appetency or predilection. There is, it seems to + me, undoubtedly something in the male organization of a special and + sexual nature, which, of its own vital force, develops the + remarkable male peculiarities so commonly seen, _and of no + imaginable use to that sex_. In as far as these peculiarities show + a great vital power, they point out to us the finest and strongest + individuals of the sex, and show us which of them would most + certainly appropriate to themselves the best and greatest number of + females, and leave behind them the strongest and greatest number of + progeny. And here would come in, as it appears to me, the proper + application of Darwin's theory of Natural Selection; _for the + possessors of greatest vital power being those most frequently + produced and reproduced, the external signs of it would go on + developing in an ever increasing exaggeration_, only to be checked + where it became really detrimental in some respect or other to the + individual[117]." + + [117] _Darwinism_, pp.[typo: period missing in scan] 296-7: italics + mine. + +Here then the idea is, as more fully expressed by Mr. Wallace in the +context, that all the innumerable, frequently considerable, and +generally elaborate "peculiarities of form, structure, colour, and +ornament," which Darwin attributed to sexual selection, are really due +to "the laws of growth." Diverse, definite, and constant though these +specific peculiarities be, they are all but the accidental or +adventitious accompaniments of "vigour," or "vital power," due to +natural selection. Now, without waiting to dispute this view, which has +already been dealt with in the chapter on Sexual Selection in Part I, it +necessarily follows that "a large proportional number of specific +characters," which, while presenting "no imaginable use," are very much +less remarkable, less considerable, less elaborate, &c., must likewise +be due to this "correlation with vital power." But if the principle of +correlation is to be extended in this vague and general manner, it +appears to me that the difference between Mr. Wallace and myself, with +respect to the principle of utility, is abolished. For of course no one +will dispute that the prime condition to the occurrence of "specific +characters," whether useful or useless, is the existence of some form +which has been denominated a "species" to present them; and this is +merely another way of saying that such characters cannot arise except in +correlation with a general fitness due to natural selection. Or, to put +the case in Mr. Wallace's own words--"This development [of useless +specific characters] will necessarily proceed by the agency of natural +selection [as a necessary condition] _and the general laws which +determine the production of colour and of ornamental appendages_." The +case, therefore, is just the same as if one were to say, for example, +that all the ailments of animals and plants proceed from correlation +with life (as a necessary condition), "and the general laws which +determine the production" of ill-health, or of specific disease. In +short, the word "correlation" is here used in a totally different sense +from that in which it is used by Darwin, and in which it is elsewhere +used by Wallace for the purpose of sustaining his doctrine of specific +characters as necessarily useful. To say that a useless character A is +correlated with a useful one B, is a very different thing from saying +that A is "correlated with vital power," or with the general conditions +to the existence of the species to which it belongs. So far as the +present discussion is concerned, no exception need be taken to the +latter statement. For it simply surrenders the doctrine against which I +am contending. + + +IV. _Isolation._ + +It is the opinion of many naturalists who are well entitled to have an +opinion upon the subject, that, in the words of Mr. Dixon, "Isolation +can preserve a non-beneficial as effectually as natural selection can +preserve a beneficial variation[118]." The ground on which this doctrine +rests is thus clearly set forth by Mr. Gulick:--"The fundamental cause +of this seems to lie in the fact that no two portions of a species +possess exactly the same average characters; and, therefore, that the +initial differences are for ever reacting on the environment and on each +other in such a way as to ensure increasing divergence in each +generation, as long as the individuals of the two groups are kept from +intergenerating[119]." In other words, as soon as a portion of a species +is separated from the rest of that species, so that breeding between the +two portions is no longer possible, the general average of characters in +the separated portion not being in all respects precisely the same as it +is in the other portion, the result of in-breeding among all individuals +of the separated portion will eventually be different from that which +obtains in the other portion; so that, after a number of generations, +the separated portion may become a distinct species from the effect of +isolation alone. Even without the aid of isolation, any original +difference of average characters may become, as it were, magnified in +successive generations, provided that the divergence is not harmful to +the individuals presenting it, and that it occurs in a sufficient +proportional number of individuals not to be immediately swamped by +intercrossing. For, as Mr. Murphy has pointed out, in accordance with +DelbÅ“uf's law, "if, in any species, a number of individuals, bearing a +ratio not infinitely small to the entire number of births, are in every +generation born with a particular variation which is neither beneficial +nor injurious, and if it be not counteracted by reversion, then the +proportion of the new variety to the original form will increase till it +approaches indefinitely near to equality[120]." Now even Mr. Wallace +himself allows that this must be the case; and thinks that in these +considerations we may find an explanation of the existence of certain +definite varieties, such as the melanic form of the jaguar, the brindled +or ring-eyed guillemot, &c. But, on the other hand, he thinks that such +varieties must always be unstable, and continually produced in varying +proportions from the parent forms. We need not, however, wait to dispute +this arbitrary assumption, because we can see that it fails, even as an +assumption, in all cases where the superadded influence of isolation is +concerned. Here there is nothing to intercept the original tendency to +divergent evolution, which arises directly out of the initially +different average of qualities presented by the isolated section of the +species, as compared with the rest of that species[121]. + + [118] _Nature_, vol. xxxiii. p. 100. + + [119] _Divergent Evolution through Cumulative Segregation_, Linn. + Journ. Zoology, vol. xx. p. 215. + + [120] _Habit and Intelligence_, p. 241. + + [121] Allusion may here again be made to the case of the niata + cattle. For here is a case where a very extreme variety is + certainly not unstable, nor produced in varying proportions + from the parent form. Moreover, as we have seen in the + preceding chapter, this almost monstrous variety most probably + originated as an individual sport--being afterwards maintained + and multiplied for a time by artificial selection. Now, + whether or not this was the case, we can very well see that it + may have been. Hence it will serve to illustrate another + possibility touching the origin and maintenance of useless + specific characters. For what is to prevent an individual + congenital variation of any kind (provided it be not harmful) + from perpetuating itself as a "varietal," and eventually, + should offspring become sufficiently numerous, a "specific + character"? There is nothing to prevent this, save panmixia, + or the presence of free intercrossing. But, as we shall see in + the next division of this treatise, there are in nature many + forms of isolation. Hence, as often as a small number of + individuals may have experienced isolation in any of its + forms, opportunity for perpetuation will have been given to + any congenital variations which may happen to arise. Should + any of these be pronounced variations, it would afterwards be + ranked as a specific character. I do not myself think that + this is the way in which indifferent specific characters + _usually_ originate. On the contrary, I believe that their + origin is most frequently due to the influence of isolation on + the average characters of the whole population, as briefly + stated in the text. But here it seems worth while to notice + this possibility of their occasionally arising as merely + individual variations, afterwards perpetuated by any of the + numerous isolating conditions which occur in nature. For, if + this can be the case with a varietal form so extreme as to + border on the monstrous, much more can it be so with such + minute differences as frequently go to constitute specific + distinctions. It is the business of species-makers to search + out such distinctions, no matter how trivial, and to record + them as "specific characters." Consequently, wherever in + nature a congenital variation happens to arise, and to be + perpetuated by the force of heredity alone under any of the + numerous forms of isolation which occur in nature, there will + be a case analogous to that of the niata cattle. + +As we shall have to consider the important principle of isolation more +fully on a subsequent occasion, I need not deal with it in the present +connexion, further than to remark that in this principle we have what +appears to me a full and adequate condition to the rise and continuance +of specific characters which need not necessarily be adaptive +characters. And, when we come to consider the facts of isolation more +closely, we shall find superabundant evidence of this having actually +been the case. + + +V. _Laws of Growth._ + +Under this general term Darwin included the operation of all unknown +causes internal to organisms leading to modifications of form or +structure--such modifications, therefore, appearing to arise, as he says +"spontaneously," or without reference to utility. That he attributed no +small importance to the operation of these principles is evident from +the last edition of the _Origin of Species_. But as these "laws of +growth" refer to causes confessedly unknown, I will not occupy space by +discussing this division of our subject--further than to observe that, +as we shall subsequently see, many of the facts which fall under it are +so irreconcilably adverse to the Wallacean doctrine of specific +characters as universally adaptive, that in the face of them Mr. Wallace +himself appears at times to abandon his doctrine _in toto_. + + + + +CHAPTER IX. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_continued_). + + +It must have appeared strange that hitherto I should have failed to +distinguish between "true species" and merely "climatic varieties." But +it will conduce to clearness of discussion if we consider our subject +point by point. Therefore, having now given a fair statement of the +facts of climatic variation, I propose to deal with their theoretical +implications--especially as regards the distinction which naturalists +are in the habit of drawing between them and so-called true species. + +First of all, then, what is this distinction? Take, for example, the +case of the Porto Santo rabbits. To almost every naturalist who reads +what has been said touching these animals, it will have appeared that +the connexion in which they are adduced is wholly irrelevant to the +question in debate. For, it will be said that the very fact of the +seemingly specific differentiation of these animals having proved to be +illusory when some of them were restored to their ancestral conditions, +is proof that their peculiar characters are not specific characters; but +only what Mr. Wallace would term "individual characters," or variations +that are not _inherited_. And the same remark applies to all the other +cases which have been adduced to show the generality and extent of +climatic variation, both in other animals and also in plants. Why, then, +it will be asked, commit the absurdity of adducing such cases in the +present discussion? Is it not self-evident that however general, or +however considerable, such merely individual, or non-heritable, +variations may be, they cannot possibly have ever had anything to do +with the origin of _species_? Therefore, is it not simply preposterous +to so much as mention them in relation to the question touching the +utility of specific characters? + +Well, whether or not it is absurd and preposterous to consider climatic +variations in connexion with the origin of species, will depend, and +depend exclusively, on what it is that we are to understand by a +species. Hitherto I have assumed, for the sake of argument, that we all +know what is meant by a species. But the time has now come for showing +that such is far from being the case. And as it would be clearly absurd +and preposterous to conclude anything with regard to specific characters +before agreeing upon what we mean by a character as specific, I will +begin by giving all the logically possible definitions of a species. + +1. _A group of individuals descended by way of natural generation from +an originally and specially created type._ + +This definition may be taken as virtually obsolete. + +2. _A group of individuals which, while fully fertile_ inter se, _are +sterile with all other individuals--or, at any rate, do not generate +fully fertile hybrids._ + +This purely physiological definition is not nowadays entertained by any +naturalist. Even though the physiological distinction be allowed to +count for something in otherwise doubtful cases, no systematist would +constitute a species on such grounds alone. Therefore we need not +concern ourselves with this definition, further than to observe that it +is often taken as more or less supplementary to each of the following +definitions. + +3. _A group of individuals which, however many characters they share +with other individuals, agree in presenting one or more characters of a +peculiar kind, with some certain degree of distinctness._ + +In this we have the definition which is practically followed by all +naturalists at the present time. But, as we shall presently see more +fully, it is an extremely lax definition. For it is impossible to +determine, by any fixed and general rule, what degree of distinctness on +the part of peculiar characters is to be taken as a uniform standard of +specific separation. So long as naturalists believed in special +creation, they could feel that by following this definition (3) they +were at any rate doing their best to tabulate very real distinctions in +nature--viz. between types as originally produced by a supernatural +cause, and as subsequently more or less modified (i.e. within the limits +imposed by the test of cross-fertility) by natural causes. But +evolutionists are unable to hold any belief in such real distinctions, +being confessedly aware that all distinctions between species and +varieties are purely artificial. So to speak, they well know that it is +they themselves who create species, by determining round what degrees of +differentiation their diagnostic boundaries shall be drawn. And, seeing +that these degrees of differentiation so frequently shade into one +another by indistinguishable stages (or, rather, that they _always_ do +so, unless intermediate varieties have perished), modern naturalists are +well awake to the impossibility of securing any approach to a uniform +standard of specific distinction. On this account many of them feel a +pressing need for some firmer definition of a species than this +one--which, in point of fact, scarcely deserves to be regarded as a +definition at all, seeing that it does not formulate any definite +criterion of specific distinctness, but leaves every man to follow his +own standards of discrimination. Now, as far as I can see, there are +only two definitions of a species which will yield to evolutionists the +steady and uniform criterion required. These two definitions are as +follows. + +4. _A group of individuals which, however many characters they share +with other individuals, agree in presenting one or more characters of a +peculiar and hereditary kind, with some certain degree of distinctness._ + +It will be observed that this definition is exactly the same as the last +one, save in the addition of the words "and hereditary." But, it is +needless to say, the addition of these words is of the highest +importance, inasmuch as it supplies exactly that objective and rigid +criterion of specific distinctness which the preceding definition lacks. +It immediately gets rid of the otherwise hopeless wrangling over species +as "good" and "bad," or "true" and "climatic," of which (as we have +seen) Kerner's essay is such a remarkable outcome. Therefore +evolutionists have more and more grown to lay stress on the hereditary +character of such peculiarities as they select for diagnostic features +of specific distinctness. Indeed it is not too much to say that, at the +present time, evolutionists in general recognize this character as, +theoretically, indispensable to the constitution of a species. But it is +likewise not too much to say that, practically, no one of our systematic +naturalists has hitherto concerned himself with this matter. At all +events, I do not know of any who has ever taken the trouble to ascertain +by experiment, with regard to any of the species which he has +constituted, whether the peculiar characters on which his diagnoses have +been founded are, or are not, hereditary. Doubtless the labour of +constituting (or, still more, of _re_-constituting) species on such a +basis of experimental inquiry would be insuperable; while, even if it +could be accomplished, would prove undesirable, on account of the chaos +it would produce in our specific nomenclature. But, all the same, we +must remember that this nomenclature as we now have it--and, therefore, +the partitioning of species as we have now made them--has no reference +to the criterion of heredity. Our system of distinguishing between +species and varieties is not based upon the definition which we are now +considering, but upon that which we last considered--frequently coupled, +to some undefinable extent, with No. 2. + +5. There is, however, yet another and closer definition, which may be +suggested by the ultra-Darwinian school, who maintain the doctrine of +natural selection as the only possible cause of the origin of species, +namely:-- + +_A group of individuals which, however many characters they share with +other individuals, agree in presenting one or more characters of a +peculiar, hereditary, and adaptive kind, with some certain degree of +distinctness._ + +Of course this definition rests upon the dogma of utility as a necessary +attribute of characters _quâ_ specific--i.e. the dogma against which the +whole of the present discussion is directed. Therefore all I need say +with reference to it is, that at any rate it cannot be adduced in any +argument where the validity of its basal dogma is in question. For it +would be a mere begging of this question to argue that every species +must present at least one peculiar and adaptive character, because, +according to definition, unless an organic type does present at least +one such character, it is not a specific type. Moreover, and quite apart +from this, it is to be hoped that naturalists as a body will never +consent to base their diagnostic work on what at best must always be a +highly speculative extension of the Darwinian theory. While, lastly, if +they were to do so with any sort of consistency, the precise adaptation +which each peculiar character subserves, and which because of this +adaptation is constituted a character of specific distinction, would +have to be determined by actual observation. For no criterion of +specific distinction could be more vague and mischievous than this one, +if it were to be applied on grounds of mere inference that such and such +a character, because seemingly constant, must "necessarily" be either +useful, vestigial, or correlated. + +Such then, as far as I can see, are all the definitions of a species +that are logically possible[122]. Which of them is chosen by those who +maintain the necessary usefulness of all specific characters? Observe, +it is for those who maintain this doctrine to choose their definition: +it is not for me to do so. My contention is, that the term does not +admit of any definition sufficiently close and constant to serve as a +basis for the doctrine in question--and this for the simple reason that +species-makers have never agreed among themselves upon any criterion of +specific distinction. My opponents, on the other hand, are clearly bound +to take an opposite view, because, unless they suppose that there is +some such definition of a species, they would be self-convicted of the +absurdity of maintaining a great generalization on a confessedly +untenable basis. For example, a few years ago I was allowed to raise a +debate in the Biological Section of the British Association on the +question to which the present chapters are devoted. But the debate ended +as I had anticipated that it must end. No one of the naturalists present +could give even the vaguest definition of what was meant by a +species--or, consequently, of a character as specific. On this account +the debate ended in as complete a destruction as was possible of the +doctrine that all the distinctive characters of every species must +necessarily be useful, vestigial, or correlated. For it became +unquestionable that the same generalization admitted of being made, with +the same degree of effect, touching all the distinctive characters of +every "snark." + + [122] It is almost needless to say that by a definition as "logical" + is meant one which, while including all the differentiae of + the thing defined, excludes any qualities which that thing may + share in common with any other thing. But by definitions as + "logically possible" I mean the number of separate definitions + which admit of being correctly given of the same thing from + different points of view. Thus, for instance, in the present + case, since the above has been in type the late M. + Quatrefages' posthumous work on _Darwin et ses Précurseurs + Français_ has been published, and gives a long list of + definitions of the term "species" which from time to time have + been enunciated by as many naturalists of the highest standing + as such (pp. 186-187). But while none of these twenty or more + definitions is logical in the sense just defined, they all + present one or other of the differentiae given by those in the + text. + +Probably, however, it will be thought unfair to have thus sprung a +difficult question of definition in oral debate. Therefore I allude to +this fiasco at the British Association, merely for the purpose of +emphasizing the necessity of agreeing upon some definition of a species, +before we can conclude anything with regard to the generalization of +specific characters as necessarily due to natural selection. But when a +naturalist has had full time to consider this fundamental matter of +definition, and to decide on what his own shall be, he cannot complain +of unfairness on the part of any one else who holds him to what he thus +says he means by a species. Now Mr. Wallace, in his last work, has given +a matured statement of what it is that he means by a species. This, +therefore, I will take as the avowed basis of his doctrine touching the +necessary origin and maintenance of all specific characters by natural +selection. His definition is as follows:-- + + "An assemblage of individuals which have become somewhat modified + in structure, form, and constitution, _so as to adapt them to + slightly different conditions of life_; which can be differentiated + from allied assemblages; which reproduce their like; which usually + breed together; and, perhaps, when crossed with their near allies, + always produce offspring which are more or less sterile _inter + se_[123]." + + [123] Darwinism, p. 167. + +From this definition the portion which I have italicized must be omitted +in the present discussion, for the reasons already given while +considering definition No. 5. What remains is a combination of Nos. 2 +and 4. According to Mr. Wallace, therefore, our criterion of a species +is to be the heredity of peculiar characters, combined, perhaps, with a +more or less exclusive fertility of the component individuals _inter +se_. This is the basis on which his generalization of the utility of +specific characters as necessary and universal is reared. Here, then, we +have something definite to go upon, at all events as far as Mr. Wallace +is concerned. Let us see how far such a basis of definition is competent +to sustain his generalization. + +First of all it must be remarked that, as species have actually been +constituted by systematists, the test of exclusive fertility does not +apply. For my own part I think this is to be regretted, because I +believe that such is the only natural--and therefore the only +firm--basis on which specific distinctions can be reared. But, as +previously observed, this is not the view which has been taken by our +species-makers. At most they regard the physiological criterion as but +lending some additional weight to their judgement upon morphological +features, in cases where it is doubtful whether the latter alone are of +sufficient distinctness to justify a recognition of specific value. Or, +conversely, if the morphological features are clearly sufficient to +justify such a recognition, yet if it happens to be known that there is +full fertility between the form presenting them and other forms which do +not, then the latter fact will usually prevent naturalists from +constituting the well differentiated form a species on grounds of its +morphological features alone--as, for instance, in the case of our +domesticated varieties. In short, the physiological criterion has not +been employed with sufficient closeness to admit of its being now +comprised within any practical definition of the term "species"--if by +this term we are to understand, not what any one may think species +_ought to be_, but what species actually _are_, as they have been +constituted for us by their makers. + +From all this it follows that the definition of the term "species" on +which Mr. Wallace relies for his deduction with respect to specific +characters, is the definition No. 4. In other words, omitting his +_petitio principii_ and his allusion to the test of fertility, the great +criterion in his view is the criterion of Heredity. And in this all +other evolutionists, of whatever school, will doubtless agree with him. +They will recognize that it is really the distinguishing test between +"climatic varieties" and "true species," so that however widely or +however constantly the former may diverge from one another in regard to +their peculiar characters, they are not to be classed among the latter +unless their peculiar characters are likewise hereditary characters. + +Now, if we are all agreed so far, the only question that remains is +whether or not this criterion of Heredity is capable of supplying a +basis for the generalization, that all characters which have been ranked +as of specific value must necessarily be regarded as presenting also an +adaptive, or life-serving, value? I will now endeavour to show that +there are certain very good reasons for answering this question in the +negative. + + +(A.) + +In the first place, even if the modifications induced by the direct +action of a changed environment are not hereditary, who is to know that +they are not? Assuredly not the botanist or zoologist who in a +particular area finds what he is fully entitled to regard as a +well-marked specific type. Only by experiments in transposition could it +be proved that the modifications have been produced by local conditions; +and although the researches of many experimentalists have shown how +considerable and how constant such modifications may be, where is the +systematic botanist who would ever think of transplanting an apparently +new species from one distant area to another before he concludes that it +is a new species? Or where is the systematic zoologist who would take +the trouble to transport what appears to be an obviously endemic species +of animal from one country to another before venturing to give it a new +specific name? No doubt, both in the case of plants and animals, it is +tacitly assumed that constant differences, if sufficient in amount to be +regarded as specific differences are hereditary; but there is not one +case in a hundred where the validity of this assumption has ever been +tested by experiments in transposition. Therefore naturalists are apt to +regard it as remarkable when the few experiments which have been made in +this direction are found to negative their assumption--for example, +that a diagnostic character in species of the genus _Hieratium_ is found +by transplantation not to be hereditary, or that the several named +species of British trout are similarly proved to be all "local +varieties" of one another. But, in point of fact, there ought to be +nothing to surprise us in such results--unless, indeed, it is the +unwarrantable nature of the assumption that any given differences of +size, form, colour, &c., which naturalists may have regarded as of +specific value, are, on this account, hereditary. Indeed, so surprising +is this assumption in the face of what we know touching both the extent +and the constancy of climatic variation, that it seems to me such a +naturalist as Kerner, who never considers the criterion of heredity at +all, is less assailable than those who profess to constitute this their +chief criterion of specific distinction. For it is certain that whatever +their professions may have nowadays become, systematic naturalists have +never been in the habit of really following this criterion. In theory +they have of late years attached more and more weight to definition No. +4; but in practice they have always adopted definition No. 3. The +consequence is, that in literally numberless cases (particularly in the +vegetable kingdom) "specific characters" are assumed to be hereditary +characters merely because systematic naturalists have bestowed a +specific name on the form which presents them. Nor is this all. For, +conversely, even when it is known that constant morphological characters +are unquestionably hereditary characters, if they happen to present but +small degrees of divergence from those of allied forms, then the form +which presents them is not ranked as a species, but as a constant +variety. In other words, when definitions 3 and 4 are found to clash, it +is not 4, but 3, that is followed. In short, even up to the present +time, systematic naturalists play fast and loose with the criterion of +Heredity to such an extent, that, as above observed, it has been +rendered wellnigh worthless in fact, whatever may be thought of it in +theory. + +Now, unless all this can be denied, what is the use of representing that +a species is distinguished from a variety--"climatic" or otherwise--by +the fact that its constituent individuals "reproduce their like"? We are +not here engaged on any abstract question of what might have been the +best principles of specific distinction for naturalists to have adopted. +We are engaged on the practical question of the principles which they +actually have adopted. And of these principles the reproduction of like +by like, under all circumstances of environment, has been virtually +ignored. + + +(B.) + +In the second place, supposing that the criterion of Heredity had been +as universally and as rigidly employed by our systematists in their work +of constructing species as it has been but occasionally and loosely +employed, could it be said that even then a basis would have been +furnished for the doctrine that all specific characters must necessarily +be useful characters? Obviously not, and for the following reasons. + +It is admitted that climatic characters are not necessarily--or even +generally--useful characters. Consequently, if there be any reason for +believing that climatic characters may become in time hereditary +characters, the doctrine in question would collapse, even supposing that +all specific types were to be re-constituted on a basis of experimental +inquiry, for the purpose of ascertaining which of them conform to the +test of Heredity. Now there are very good reasons for believing that +climatic characters not unfrequently do become hereditary characters; +and it was mainly in view of those reasons that I deemed it worth while +to devote so much space in the preceding chapter to the facts of +climatic variation. I will now state the reasons in question under two +different lines of argument. + +We are not as yet entitled to conclude definitely against the possible +inheritance of acquired characters. Consequently, we are not as yet +entitled to assume that climatic characters--i. e. characters acquired +by converse with a new environment, continued, say, since the last +glacial period--can never have become congenital characters. But, if +they ever have become congenital characters, they will have become, at +all events as a general rule, congenital characters that are useless; +for it is conceded that, _quâ_ climatic characters, they have not been +due to natural selection. + +Doubtless the followers of Weismann will repudiate this line of +argument, if not as entirely worthless, at all events as too +questionable to be of much practical worth. But even to the followers of +Weismann it may be pointed out, that the Wallacean doctrine of the +origin of all specific characters by means of natural selection was +propounded many years before either Galton or Weismann had questioned +the transmission of acquired characters. However. I allow that this line +of argument has now become--for the time being at all events--a dubious +line, and will therefore at once pass on to the second line, which is +not open to doubt from any quarter. + +Whether or not we accept Weismann's views, it will here be convenient to +employ his terminology, since this will serve to convey the somewhat +important distinctions which it is now my object to express. + +In the foregoing paragraphs, under heading (A), we have seen that there +must be "literally numberless forms" which have been ranked as true +species, whose diagnostic characters are nevertheless not congenital. In +the case of plants especially, we know that there must be large numbers +of named species which do not conform to the criterion of Heredity, +although we do not know which species they are. For present purposes, +however, it is enough for us to know that there are many such named +species, where some change of environment has acted directly and +similarly on all the individual "somas" exposed to it, without affecting +their "germ-plasms," or the material bases of their hereditary +qualities. For named species of this kind we may employ the term +_somatogenetic species_. + +But now, if there are any cases where a change of environment does act +on the germ-plasms exposed to it, the result would be what we may call +_blastogenetic species_--i.e. species which conform to the criterion of +Heredity, and would therefore be ranked by all naturalists as "true +species." It would not signify in such a case whether the changed +conditions of life first affected the soma, and then, through changed +nutrition, the germ-plasm; or whether from the first it directly +affected the germ-plasm itself. For in either case the result would be a +"species," which would continue to reproduce its peculiar features by +heredity. + +Now, the supposition that changed conditions of life may thus affect the +congenital endowments of germ-plasm is not a gratuitous one. The sundry +facts already given in previous chapters are enough to show that the +origin of a blastogenetic species by the direct action on germ-plasm of +changed conditions of life is, at all events, a possibility. And a +little further thought is enough to show that this possibility becomes a +probability--if not a virtual certainty. Even Weismann--notwithstanding +his desire to maintain, as far as he possibly can, the "stability" of +germ-plasm--is obliged to allow that external conditions acting on the +organism may in some cases modify the hereditary qualities of its +germ-plasm, and so, as he says, "determine the phyletic development of +its descendants." Again, we have seen that he is compelled to interpret +the results of his own experiments on the climatic varieties of certain +butterflies by saying, "I cannot explain the facts otherwise than by +supposing the passive acquisition of characters produced by direct +influences of climate"; by which he means that in this case the +influence of climate acts directly on the hereditary qualities of +germ-plasm. Lastly, and more generally, he says:-- + + "But although I hold it improbable that individual variability can + depend on a direct action of external influences upon the + germ-cells and their contained germ-plasm, because--as follows from + sundry facts--the molecular structure of the germ-plasm must be + very difficult to change, yet it is by no means to be implied that + this structure may not possibly be altered by influences of the + same kind continuing for a very long time. Thus it seems to me the + possibility is not to be rejected, that influences continued for a + long time, that is, for generations, such as temperature, kind of + nourishment, &c., which may affect the germ-cells as well as any + other part of the organism, may produce a change in the + constitution of the germ-plasm. But such influences would not then + produce individual variation, but would necessarily modify in the + same way all the individuals of a species living in a certain + district. It is possible, though it cannot be proved, that many + climatic varieties have arisen in this manner." + +So far, then, we have testimony to this point, as it were, from a +reluctant witness. But if we have no theory involving the "stability of +germ-plasm" to maintain, we can scarcely fail to see how susceptible the +germ-plasm is likely to prove to changed conditions of life. For we know +how eminently susceptible it is in this respect when gauged by the +practical test of fertility; and as this is but an expression of its +extraordinarily complex character, it would indeed be surprising if it +were to enjoy any immunity against modification by changed conditions of +life. We have seen in the foregoing chapter how frequently and how +considerably somatogenetic changes are thus caused, so as to produce +"somatogenetic species"--or, where we happen to know that the changes +are not hereditary, "climatic varieties." But the constitution of +germ-plasm is much more complex than that of any of the structures which +are developed therefrom. Consequently, the only wonder is that hitherto +experimentalists have not been more successful in producing +"blastogenetic species" by artificial changes of environment. Or, as Ray +Lankester has well stated this consideration, "It is not difficult to +suggest possible ways in which the changed conditions, shown to be +important by Darwin, could act through the parental body upon the +nuclear matter of the egg-cell and sperm-cell, with its immensely +complex and therefore unstable constitution.... The wonder is, not that +[blastogenetic] variation occurs, but that it is not excessive and +monstrous in every product of fertilization[124]." + + [124] _Nature_, Dec. 12, 1889, p. 129. + +If to this it should be objected that, as a matter of fact, +experimentalists have not been nearly so successful in producing +congenital modifications of type by changed conditions of life as they +have been in thus producing merely somatic modifications; or if it +should be further objected that we have no evidence at all in nature of +a "blastogenetic species" having been formed by means of climatic +influences alone,--if these objections were to be raised, they would +admit of the following answer. + +With regard to experiments, so few have thus far been made upon the +subject, that objections founded on their negative results do not carry +much weight--especially when we remember that these results have not +been uniformly negative, but sometimes positive, as shown in Chapter VI. +With regard to plants and animals in a state of nature, the objection is +wholly futile, for the simple reason that in as many cases as changed +conditions of life may have caused an hereditary change of specific +type, there is now no means of obtaining "evidence" upon the subject. +But we are not on this account entitled to conclude against the +probability of such changes of specific type having been more or less +frequently thus produced. And still less can we be on this account +entitled to conclude against the _possibility_ of such a change having +ever occurred in any single instance. Yet this is what must be concluded +by any one who maintains that the origin of all species--and, _a +fortiori_, of all specific characters--must _necessarily_ have been due +to natural selection. + +Now, if all this be admitted--and I do not see how it can be reasonably +questioned--consider how important its bearing becomes on the issue +before us. If germ-plasm (using this term for whatever it is that +constitutes the material basis of heredity) is ever capable of having +its congenital endowments altered by the direct action of external +conditions, the resulting change of hereditary characters, whatever else +it may be, need not be an adaptive change. Indeed, according to +Weismann's theory of germ-plasm, the chances must be infinitely against +the change being an adaptive one. On the theory of pangenesis--that is +to say, on the so-called Lamarckian principles--there would be much more +reason for entertaining the possibly adaptive character of hereditary +change due to the direct action of the environment. Therefore we arrive +at this curious result. The more that we are disposed to accept +Weismann's theory of heredity, and with it the corollary that natural +selection is the sole cause of adaptive modification in species the less +are we entitled to assume that all specific characters must necessarily +be adaptive. Seeing that in nature there are presumably many cases like +those of Hoffmann's plants, Weismann's butterflies, &c., where the +hereditary qualities of germ-plasm have (on his hypothesis) been +modified by changed conditions of life, we are bound to believe that, in +all cases where such changes do not happen to be actively deleterious, +they will persist. And inasmuch as characters which are only of +"specific" value must be the characters most easily--and therefore most +frequently--induced by any slight changes in the constitution of +germ-plasm, while, for the same reason (namely, that of their trivial +nature) they are least likely to prove injurious, it follows that the +less we believe in the functionally-produced adaptations of Lamarck, the +more ought we to resist the assumption that all specific characters must +necessarily be adaptive characters. + + * * * * * + +Upon the whole, then, and with regard to the direct action of external +conditions, I conclude--not only from general considerations, but also +from special facts or instances quite sufficient for the purpose--that +these must certainly give rise to immense numbers of somatogenetic +species on the one hand, and probably to considerable numbers of +blastogenetic species on the other; that in neither case is there any +reason for supposing the distinctively "specific characters" to be other +than "neutral" or "indifferent"; while there are the best of reasons for +concluding the contrary. So that, under this division of our subject +alone (B), there appears to be ample justification for the statement +that "a large proportional number of specific characters" are in +reality, as they are in appearance, destitute of significance from a +utilitarian point of view. + + +(C.) + +Thus far in the present chapter we have been dealing exclusively with +the case of "climatic variation," or change of specific type due to +changes in the external conditions of life. But it will be remembered +that, in the preceding chapter, allusion was likewise made to changes of +specific type due to internal causes, or to what Darwin has called "the +nature of the organism." Under this division of our subject I mentioned +especially Sexual Selection, which is supposed to arise in the aesthetic +taste of animals themselves; Isolation, which is supposed to originate +new types by allowing the average characters of an isolated section of +an old type to develop a new history of varietal change, as we shall see +more fully in the ensuing part of this treatise; and the Laws of Growth, +which is a general term for the operation of unknown causes of change +incidental to the living processes of organisms which present the +change. + +Now, under none of these divisions of our subject can there be any +question touching the criterion of Heredity. For if new species--or even +single specific characters of new species--are ever produced by any of +these causes, they must certainly all "reproduce their like." Therefore +the only question which can here obtain is as to whether or not such +causes ever do originate new species, or even so much as new specific +characters. Mr. Wallace, though not always consistently, answers this +question in the negative; but the great majority of naturalists follow +Darwin by answering it in the affirmative. And this is enough to show +the only point which we need at present concern ourselves with +showing--viz. that the question is, at the least, an open one. For as +long as this question is an open one among believers in the theory of +natural selection, it must clearly be an unwarrantable deduction from +that theory, that all species, and _a fortiori_ all specific characters, +are necessarily due to natural selection. The deduction cannot be +legitimately drawn until the possibility of any other cause of specific +modification has been excluded. But the bare fact of the question as +just stated being still and at the least an open question, is enough to +prove that this possibility has not been excluded. Therefore the +deduction must be, again on this ground alone (C), unwarrantable. + + * * * * * + +Such are my several reasons--and it is to be observed that they are all +_independent_ reasons--for concluding that it makes no practical +difference to the present discussion whether or not we entertain +Heredity as a criterion of specific distinction. Seeing that our +species-makers have paid so little regard to this criterion, it is +neither absurd nor preposterous to have adduced, in the preceding +chapter, the facts of climatic variation. On the contrary, as the +definition of "species" which has been practically followed by our +species-makers in No. 3, and not No. 4, these facts form part and parcel +of our subject. It is perfectly certain that, in the vegetable kingdom +at all events, "a large proportional number" of specifically diagnostic +characters would be proved by experiment to be "somatogenetic"; while +there are numerous constant characters classed as varietal, although it +is well known that they are "blastogenetic." Moreover, we can scarcely +doubt that many specific characters which are also hereditary characters +owe their existence, not to natural selection, but to the direct action +of external causes on the hereditary structure of "germ-plasm"; while, +even apart from this consideration, there are at least three distinct +and highly general principles of specific change, which are accepted by +the great majority of Darwinists, and the only common peculiarity of +which is that they produce hereditary changes of specific types without +any reference to the principle of utility. + + + + +CHAPTER X. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_concluded_). + + +Our subject is not yet exhausted. For it remains to observe the +consequences which arise from the dogma of utility as the only _raison +d'être_ of species, or of specific characters, when this dogma is +applied in practice by its own promoters. + + * * * * * + +Any definition of "species"--excepting Nos. 1, 2, and 5, which may here +be disregarded--must needs contain some such phrase as the one with +which Nos. 3 and 4 conclude. This is, that peculiar characters, in order +to be recognized as of specific value, must present neither more nor +less than "some certain degree of distinctness." If they present more +than this degree of distinctness, the form, or forms, in question must +be ranked as generic; while if they present less than this degree of +distinctness, they must be regarded as varietal--and this even if they +are known to be mutually sterile. What, then, is this certain degree of +distinctness? What are its upper and lower limits? This question is one +that cannot be answered. From the very nature of the case it is +impossible to find a uniform standard of distinction whereby to draw +our boundary lines between varieties and species on the one hand, or +between species and genera on the other. One or two quotations will be +sufficient to satisfy the general reader upon this point. + +Mr. Wallace himself alludes to "the great difficulty that is felt by +botanists in determining the limits of species in many large genera," +and gives as examples well-known instances where systematic botanists of +the highest eminence differ hopelessly in their respective estimates of +"specific characters." Thus:-- + + "Mr. Baker includes under a single species, Rosa canina, no less + than twenty-eight named varieties distinguished by more or less + constant characters, and often confined to special localities, and + to these are referred about seventy of the species of British and + continental botanists. Of the genus Rubus or bramble, five British + species are given in Bentham's _Handbook of British Flora_, while + in the fifth edition of Babington's _Manual of British Botany_, + published about the same time, no less than forty-five species are + described. Of willows (Salix) the same two works enumerate fifteen + and thirty-one species respectively. The hawkweeds (Hieracium) are + equally puzzling, for while Mr. Bentham admits only seven British + species, Professor Babington describes no less than seventy-two, + besides several named varieties[125]." + + [125] _Darwinism_, p. 77. + +Mr. Wallace goes on to quote further instances, such as that of Draba +verna, which Jordan has found to present, in the south of France alone, +no less than fifty-two permanent varieties, which all "come true from +seed, and thus present all the characteristics of a true species"; so +that, "as the plant is very common almost all over Europe, and ranges +from North America to the Himalayas, the number of similar forms over +this wide area would probably have to be reckoned by hundreds, if not by +thousands[126]." + + [126] _Darwinism_, p. 77. + +One or two further quotations may be given to the same general effect, +selected from the writings of specialists in their several departments. + + "There is nothing that divides systematists more than what + constitutes a genus. Species that resemble each other more than + other species, is perhaps the best definition that can be given. + This is obviously an uncertain test, much depending on individual + judgement and experience; but that, in the evolution of forms, such + difficulties should arise in the limitation of genera and species + was inevitable. What is a generic character in one may be only a + specific character in another. As an illustration of the uncertain + importance of characters, I may mention the weevil genus + _Centrinus_ in which the leading characters in the classification + of the family to which it belongs are so mixed that systematists + have been content to keep the species together in a group that + cannot be defined.... No advantage or disadvantage is attached, + apparently, to any of the characters. There are about 200 species, + all American. + + The venation of the wings of insects is another example of + modifications without serving any special purpose. There is no vein + in certain Thripidae, and only a rudiment or a single vein in + Chalcididae. There are thousands of variations more or less marked, + some of the same type with comparatively trivial variation, others + presenting distinct types, even in the same family, such genera, + for example, as _Polyneura_, _Tettigetra_, _Huechys_, &c. in the + Cicadidae. + + Individual differences have often been regarded as distinctive of + species; varieties also are very deceptive, and races come very + near to species. A South-American beetle, _Arescus histrio_, has + varieties of yellow, red, and black, or these colours variously + intermixed, and, what is very unusual, longitudinal stripes in some + and transverse bars in others, and all taken in the same locality. + Mr. A. G. Butler, of the British Museum, is of opinion that 'what + is generally understood by the term species (that is to say, a + well-defined, distinct, and constant type, having no near allies) + is non-existent in the Lepidoptera, and that the nearest approach + to it in this order is a constant, though but slightly differing, + rare or local form--that genera, in fact, consist wholly of a + gradational series of such forms (Ann. Mag. Nat. Hist. 5, xix. + 103)[127].'" + + [127] Pascoe, _The Darwinian Theory of the Origin of Species_, 1891, + pp. 31-33, and 46. + +So much as regards entomology, and still living forms. In illustration +of the same principles in connexion with palaeontological series, I may +quote Würtenberger, who says:-- + + "With respect to these fossil forms [i.e. multitudinous forms of + fossil Ammonites], it is quite immaterial whether a very short or a + somewhat longer part of any branch be dignified with a separate + name, and regarded as a species. The prickly Ammonites, classed + under the designation of Armata, are so intimately connected that + it becomes impossible to separate the accepted species sharply from + one another. The same remark applies to the group of which the + manifold forms are distinguished by their ribbed shells, and are + called Planulata[128]." + + [128] _Neuer Beitrag zum geologischen Beweis der Darwinischen + Theorie_, 1873. + +I had here supplied a number of similar quotations from writers in +various other departments of systematic work, but afterwards struck them +out as superfluous. For it is not to be anticipated that any competent +naturalist will nowadays dispute that the terms "variety," "species," +and "genus" stand for merely conventional divisions, and that whether a +given form shall be ranked under one or the other of them is often no +more than a matter of individual taste. From the nature of the case +there can be no objective, and therefore no common, standards of +delimitation. This is true even as regards any one given department of +systematic work; but when we compare the standards of delimitation which +prevail in one department with those which prevail in another, it +becomes evident that there is not so much as any attempt at agreeing +upon a common measure of specific distinction. + +But what, it may well be asked, is the use of thus insisting upon +well-known facts, which nobody will dispute? Well, in the first place, +we have already seen, in the last chapter, that it is incumbent on those +who maintain that all species, or even all specific characters, must be +due to natural selection, to tell us what they mean by a species, or by +characters as specific. If I am told to believe that the definite +quality A is a necessary attribute of B, and yet that B is "not a +distinct entity," but an undefinable abstraction, I can only marvel that +any one should expect me to be so simple. But, without recurring to this +point, the use of insisting on the facts above stated is, in the second +place, that otherwise I cannot suppose any general reader could believe +them in view of what is to follow. For he cannot but feel that the cost +of believing them is to render inexplicable the mental processes of +those naturalists who, in the face of such facts, have deduced the +following conclusions. + +The school of naturalists against which I am contending maintains, as a +generalization deduced from the theory of natural selection, that all +species, or even all specific characters, must necessarily owe their +origin to the principle of utility. Yet this same school does not +maintain any such generalization, either with regard to varietal +characters on the one hand, or to generic characters on the other. On +the contrary, Professor Huxley, Mr. Wallace, and all other naturalists +who agree with them in refusing to entertain so much as the abstract +possibility of any cause other than natural selection having been +productive of species, fully accept the fact of other causes having been +largely concerned in the production of varieties, genera, families, and +all higher groups, or of the characters severally distinctive of each. +Indeed, Mr. Wallace does not question what appears to me the extravagant +estimate of Professor Cope, that the non-adaptive characters distinctive +of those higher groups are fully equal, in point of numbers, to the +adaptive. But, surely, if the theory of evolution by natural selection +is, as we all agree, a true theory of the origin of species, it must +likewise be a true theory of the origin of genera; and if it be supposed +essential to the integrity of the theory in its former aspect that all +specific characters should be held to be useful, I fail to see how, in +regard to its latter aspect, we are so readily to surrender the +necessary usefulness of all generic characters. And exactly the same +remark applies to the case of constant "varieties," where again the +doctrine of utility as universal is not maintained. Yet, according to +the general theory of evolution, constant varieties are what Darwin +termed "incipient species," while species are what may be termed +"incipient genera." Therefore, if the doctrine of utility as universal +be conceded to fail in the case of varieties on the one hand and of +genera on the other, where is the consistency in maintaining that it +must "necessarily" hold as regards the intermediate division, species? +Truly the shade of Darwin may exclaim, "Save me from my friends." And +truly against logic of this description a follower of Darwin must find +it difficult to argue. If one's opponents were believers in special +creation, and therefore stood upon some definite ground while +maintaining this difference between species and all other taxonomic +divisions, there would at least be some issue to argue about. But when +on the one hand it is conceded that species are merely arbitrary +divisions, which differ in no respect as to the process of their +evolution from either varieties or genera, while on the other hand it is +affirmed that there is thus so great a difference in the result, all we +can say is that our opponents are entangling themselves in the meshes of +a sheer contradiction. + +Or, otherwise stated, specific characters differ from varietal +characters in being, as a rule, more pronounced and more constant: on +this account advocates of utility as universal apply the doctrine to +species, while they do not feel the "necessity" of applying it to +varieties. But now, generic and all higher characters are even more +constant and more pronounced than specific characters--not to say, in +many cases, more generally diffused over a larger number of organisms +usually occupying larger areas. Therefore, _a fortiori_, if for the +reasons above stated evolutionists regard it as a necessary deduction +from the theory of natural selection that all specific characters must +be useful, much more ought it to be a necessary deduction from this +theory that all generic, and still more all higher, characters must be +useful. But, as we have seen, this is not maintained by our opponents. +On the contrary, they draw the sharpest distinction between specific and +all other characters in this respect, freely conceding that both those +below and those above them need not--and very often do not--present any +utilitarian significance. + +Although it appears to me that this doctrine is self-contradictory, and +on this ground alone might be summarily dismissed, as it is now held in +one or other of its forms by many naturalists, I will give it a more +detailed consideration in both its parts--namely, first with respect to +the distinction between varieties and species, and next with respect to +the distinction between species and genera. + + * * * * * + +Until it can be shown that species are something more than merely +arbitrary divisions, due to the disappearance of intermediate varietal +links; that in some way or another they _are_ "definite entities," which +admit of being delineated by the application of some uniform or general +principles of definition; that, in short, species have only then been +classified as such when it has been shown that the origin of each has +been due to the operation of causes which have not been concerned in the +production of varieties;--until these things are shown, it clearly +remains a gratuitous dogma to maintain that forms which have been called +species differ from forms which have been called varieties in the +important respect, that they (let alone each of all their distinctive +characters) must necessarily have been due to the principle of utility. +Yet, as we have seen, even Mr. Wallace allows that a species is "not a +distinct entity," but "an assemblage of individuals which have become +somewhat modified in structure, form, and constitution"; while estimates +of the kinds and degrees of modification which are to be taken as of +specific value are conceded to be undefinable, fluctuating, and in not a +few cases almost ludicrously divergent. + +Perhaps one cannot more forcibly present the rational value of this +position than by noting the following consequences of it. Mr. Gulick +writes me that while studying the land-shells of the Sandwich Islands, +and finding there a rich profusion of unique varieties, in cases where +the intermediate varieties were rare he could himself have created a +number of species by simply throwing these intermediate varieties into +his fire. Now it follows from the dogma which we are considering, that, +by so doing, not only would he have created new species, but at the same +time he would have proved them due to natural selection, and endowed the +diagnostic characters of each with a "necessarily" adaptive meaning, +which previously it was not necessary that they should present. Before +his destruction of these intermediate varieties, he need have felt +himself under no obligation to assume that any given character at either +end of the series was of utilitarian significance: but, after his +destruction of the intermediate forms, he could no longer entertain any +question upon the matter, under pain of being denounced as a Darwinian +heretic. + +Now the application is self-evident. It is a general fact, which admits +of no denial, that the more our knowledge of any flora or fauna +increases, the greater is the number of intermediate forms which are +brought to light, either as still existing or as having once existed. +Consequently, the more that such knowledge increases, the more does our +catalogue of "species" diminish. As Kerner says, "bad species" are +always multiplying at the expense of "good species"; or, as Oscar +Schmidt (following Häckel) similarly remarks, if we could know as much +about the latter as we do about the former, "all species, without any +exception, would become what species-makers understand by 'bad +species'[129]." Hence we see that, just as Mr. Gulick could have created +good species by secretly destroying his intermediate varieties, so has +Nature produced her "good species" for the delectation of systematists. +And just as Mr. Gulick, by first hiding and afterwards revealing his +intermediate forms, could have made the self-same characters in the +first instance necessarily useful, but ever afterwards presumably +useless, so has Nature caused the utility of diagnostic characters to +vary with our knowledge of her intermediate forms. It belongs to the +essence of our theory of descent, that in _all_ cases these intermediate +forms must either be now existing or have once existed; and, therefore, +that the work of species-makers consists in nothing more than marking +out the _lacunae_ in our knowledge of them. Yet we are bound to believe +that wherever these _lacunae_ in our knowledge occur, there occurs also +the objective necessity of causation as utilitarian--a necessity, +however, which vanishes so soon as our advancing information supplies +the intermediate forms in question. It may indeed appear strange that +the utility or non-utility of organic structures should thus depend on +the accidents of human knowledge; but this is the Darwinian faith, and +he who doubts the dogma is to be anathema. + + [129] _The Doctrine of Descent and Darwinism_, Eng. Trans. p. 102. + +Turning next to the similar distinction which it is sought to draw +between species and genera, here it will probably be urged, as I +understand it to be urged by Mr. Wallace, that generic characters (and +still more characters of families, orders, &c.) refer back to so remote +a state of things that utility may have been present at their birth +which has disappeared in their maturity. In other words, it is held that +all generic characters were originally specific characters; that as such +they were all originally of use; but that, after having been rendered +stable by heredity, many of them may have ceased to be of service to the +descendants of those species in which they originated, and whose +extinction has now made it impossible to divine what that service may +have been. + +Now, in the first place; this is not the interpretation adopted by +Darwin. For instance, he expressly contrasts such cases with those of +vestigial or "rudimentary" structures, pointing out that they differ +from vestigial structures in respect of their permanence. One quotation +will be sufficient to establish the present point. + + "A structure which has been developed through long-continued + selection, when it ceases to be of service to a species, generally + becomes variable, as we see with rudimentary organs, for it will no + longer be regulated by this same power of selection. But when, from + the nature of the organism and of the conditions, modifications + have been induced which are unimportant for the welfare of the + species, they may be, and apparently often have been, transmitted + in nearly the same state to numerous, otherwise modified, + descendants[130]." + + [130] _Origin of Species_, p. 175. + +Here, and in the context, we have a sufficiently clear statement of +Darwin's view--first, that unadaptive characters may arise in _species_ +as "fluctuating variations, which sooner or later become _constant_ +through the nature of the organism and of surrounding conditions, as +well as through the intercrossing of distinct individuals, but _not_ +through natural selection"[131]; second, that such unadaptive characters +may then be transmitted in this their stable condition to +species-progeny, so as to become distinctive of genera, families, &c.; +third, that, on account of such characters not being afterwards liable +to diverse adaptive modifications in different branches of the +species-progeny, they are of more value as indicating lines of pedigree +than are characters which from the first have been useful; and, lastly, +they are therefore now empirically recognized by systematists as of most +value in guiding the work of classification. To me it appears that this +view is not only perfectly rational in itself, but likewise fully +compatible with the theory of natural selection--which, as I have +previously shown, is _primarily_ a theory of adaptive characters, and +therefore not necessarily a theory of _all_ specific characters. But to +those who think otherwise, it must appear--and does appear--that there +is something wrong about such a view of the case--that it was not +consistent in the author of the _Origin of Species_ thus to refer +non-adaptive generic characters to a parentage of non-adaptive specific +characters. Nevertheless, as a matter of fact, Darwin was perfectly +consistent in putting forth this view, because, unlike Wallace, he was +not under the sway of any antecedent dogma erroneously deduced from the +theory of natural selection. + + [131] _Ibid._ p. 176: italics mine. + +Next without reference to Darwin's authority, let us see for ourselves +where the inconsistency really lies. To allow that generic characters +may be useless, while denying that specific characters can ever be so +(unless correlated with others that are useful), involves an appeal to +the argument from ignorance touching the ancestral habits, +life-conditions, &c., of a parent species now extinct. Well, even upon +this assumption of utility as obsolete, there remains to be explained +the "stability" of useless characters now distinctive of genera, +families, orders, and the rest. We know that specific characters which +have owed their origin to utility and have afterwards ceased to present +utility, degenerate, become variable, inconstant, "rudimentary," and +finally disappear. Why, then, should these things not happen with regard +to useless generic distinctions? Still more, why should they not happen +with regard to family, ordinal, and class distinctions? On the lines +against which I am arguing it would appear impossible that any answer to +this question can be suggested. For what explanation can be given of the +contrast thus presented between the obsolescence of specific characters +where previous utility is demonstrable, and the permanence of higher +characters whose previous utility is assumed? As we have already seen, +Mr. Wallace himself employs this consideration of permanence and +constancy against the view that any cause other than natural selection +can have been concerned in the origin and maintenance of _specific_ +characters. But he does not seem to see that the consideration cuts two +ways--and much more forcibly against his views than in favour of them. +For while, as already shown in the chapter before last, it is +sufficiently easy to dispose of the consideration as Wallace uses it (by +simply pointing out with Darwin that any causes other than natural +selection which may have been concerned in the genesis of _specific_ +characters, must, if equally uniform in their operation, equally give +rise to permanence and constancy in their results); on the other hand, +it becomes impossible to explain the stability of useless _generic_ +characters, if, as Wallace's use of the argument requires, natural +selection is the only possible cause of stability. The argument is one +that cannot be played with fast and loose. Either utility is the sole +condition to the stability of _any_ diagnostic character (in which case +it is not open to Mr. Wallace to assume that all _generic_ or higher +characters which are now useless have owed their origin to a past +utility); or else utility is not the sole condition to stability (in +which case his use of the present argument in relation to _specific_ +characters collapses). We have seen, indeed, in the chapter before last, +that his use of the argument collapses anyhow, or quite irrespective of +his inconsistent attitude towards generic characters, with which we were +not then concerned. But the point now is that, as a mere matter of +logic, the argument from stability as Wallace applies it to the case of +specific characters, is incompatible with his argument that useless +generic characters may originally have been useful specific characters. +It can scarcely be questioned that the transmutation of a species into a +genus must, as a rule, have allowed time enough for a newly +acquired--i.e. peculiar specific-character--to show some signs of +undergoing degeneration, if, as supposed, the original cause of its +development and maintenance was withdrawn when the parent species began +to ramify into its species-progeny. Yet, as Darwin says, "it is +notorious that specific characters are more variable than generic[132]." +So that, upon the whole, I do not see how on grounds of general +reasoning it is logically possible to maintain Mr. Wallace's distinction +between specific and generic characters in respect of necessary utility. + + [132] _Origin of Species_, p. 122. + +But now, and lastly, we shall reach the same conclusion if, discarding +all consideration of general principles and formal reasoning, we fasten +attention upon certain particular cases, or concrete facts. Thus, to +select only two illustrations within the limits of genera, it is a +diagnostic feature of the genus _Equus_ that small warty callosities +occur on the legs. It is impossible to suggest any useful function that +is now discharged by these callosities in any of the existing species of +the genus. If it be assumed that they must have been of some use to the +species from which the genus originally sprang, the assumption, it seems +to me, can only be saved by further assuming that in existing species of +the genus these callosities are in a vestigial condition--i. e. that in +the original or parent species they performed some function which is +now obsolete. But against these assumptions there lies the following +fact. The callosities in question are not similarly distributed through +all existing species of the genus. The horse has them upon all his four +legs, while other species have them only upon two. Therefore, if all +specific characters are necessarily due to natural selection, it is +manifest that these callosities are _not_ now vestigial: on the +contrary, they _must_ still be--or, at best, have recently been--of so +much importance to all existing species of the genus, that not only is +it a matter of selection-value to all these species that they should +possess these callosities; but it is even a matter of selection-value to +a horse that he should possess four of them, while it is equally a +matter of selection-value to the ass that he should possess only two. +Here, it seems to me, we have once more the doctrine of the necessary +utility of specific characters reduced to an absurdity; while at the +same time we display the incoherency of the distinction between specific +characters and generic characters in respect of this doctrine. For the +distinction in such a case amounts to saying that a generic character, +if evenly distributed among all the species, need not be an adaptive +character; whereas, if any one of the species presents it in a slightly +different form, the character must be, on this account, necessarily +adaptive. In other words, the uniformity with which a generic character +occurs among the species of the genus is taken to remove that character +from the necessarily useful class, while the absence of such uniformity +is taken as proof that the character must be placed within the +necessarily useful class. Which is surely no less a _reductio ad +absurdum_ with regard to the generic character than the one just +presented with regard to its variants as specific characters. And, of +course, this twofold absurdity is presented in all cases where a generic +character is unequally distributed among the constituent species of a +genus. + +[Illustration: Fig. 4.--Lower Teeth of Orang (after Tomes).] + +But here is an illustration of another class of cases. Mr. Tomes has +shown that the molar teeth of the Orang present an extraordinary and +altogether superfluous amount of attachment in their sockets--the fangs +being not only exceedingly long, and therefore deeply buried in the +jaw-bone, but also curving round one another, so as still further to +strengthen the whole[133]. In the allied genera of anthropoid apes there +is no such abnormal amount of attachment. Now, the question is, of what +conceivable use can it _ever_ have been, either to the existing genus, +or to its parent species, that such an abnormal amount of attachment +should obtain? It certainly is not required to prevent dislocation of +the teeth, seeing that in all allied genera, and even in man himself, +the amount of attachment is already so great that teeth will break +before they can be drawn by anything short of a dentist's forceps. +Therefore I conclude that this peculiarity in the dentition of the genus +must have arisen in its parent species by way of what Darwin calls a +"fluctuating variation," without utilitarian significance. And I adduce +it in the present connexion because the peculiarity is one which is +equally unamenable to a utilitarian explanation, whether it happens to +occur as a generic or a specific character. + + [133] _A Manual of Dental Anatomy_, p. 455. + +Numberless similar cases might be quoted; but probably enough has now +been said to prove the inconsistency of the distinction which our +opponents draw between specific and all higher characters in respect of +utility. In point of fact, a very little thought is enough to show that +no such distinction admits of being drawn; and, therefore, that any one +who maintains the doctrine of utility as universal in the case of +specific characters, must in consistency hold to the same doctrine in +the case of generic and all higher characters. And the fact that our +opponents are unable to do this becomes a virtual confession on their +part of the futility of the generalization which they have +propounded[134]. + + [134] It may be observed that this distinction was not propounded by + Mr. Wallace--nor, so far as I am aware, by anybody else--until + he joined issue with me on the subject of specific characters. + Whether he has always held this important distinction between + specific and generic characters, I know not; but, as + originally enunciated, his doctrine of utility as universal + was subject to no such limitation: it was stated + unconditionally, as applying to all taxonomic divisions + indifferently. The words have already been quoted on page 180; + and, if the reader will turn to them, he may further observe + that, prior to our discussion, Mr. Wallace made no allowance + for the principle of correlation, which, as we have seen, + furnishes so convenient a loop-hole of escape in cases where + even the argument from our ignorance of possible utility + appears absurd. In his latest work, however, he is much less + sweeping in his statements. He limits his doctrine to the case + of "specific characters" alone, and even with regard to them + makes unlimited drafts upon the principle of correlation. + +On what then do Mr. Wallace and his followers rely for their great +distinction between specific and all other characters in respect of +utility? This is the final and fundamental question which I must leave +these naturalists themselves to answer; for my whole contention is, that +it is unanswerable. But although I am satisfied that they have nothing +on which to base their generalization, it seems worth while to conclude +by showing yet one further point. And this is, that these naturalists +themselves, as soon as they quit merely abstract assertions and come to +deal with actual facts, contradict their own generalization. It is worth +while to show this by means of a few quotations, that we may perceive +how impossible it is for them to sustain their generalization in the +domain of fact. + +As it is desirable to be brief, I will confine myself to quoting from +Mr. Wallace. + + "Colour may be looked upon as a necessary result of the highly + complex chemical constitution of animal tissues and fluids. The + blood, the bile, the bones, the fat, and other tissues have + characteristic, and often brilliant colours, which we cannot + suppose to have been determined for any special purpose as colours, + since they are usually concealed. The external organs and + integuments, would, by the same general laws, naturally give rise + to a greater variety of colour[135]." + + [135] _Darwinism_, p. 297. + +Surely comment is needless. Have the colour of external organs and +integuments nothing to do with the determining of specific distinctions +by systematists? Or, may we not rather ask, are there any other +"characters" which have had more to do with their delineation of animal +species? Therefore, if "the external organs and integuments naturally +give rise to a greater variety of colours," for non-utilitarian reasons, +than is the case with internal organs and tissues; while even the latter +present, for similarly non-utilitarian reasons, such variety and +intensity of colours as they do; must it not follow that, on the ground +of the "Laws of Growth" alone, Mr. Wallace has conceded the entire case +as regards "a large proportional number of specific characters" being +non-adaptive--"spontaneous" in their occurrence, and "meaningless" in +their persistence? + +Once more:-- + + "The enormously lengthened plumes of the bird of paradise and of + the peacock, can, however, have no such use [i.e. for purposes of + defence], but must be rather injurious than beneficial in the + birds' ordinary life. The fact that they have been developed to so + great an extent in a few species is an indication of such perfect + adaptation to the conditions of existence, such complete success in + the battle for life, that there is, in the adult male at all + events, a surplus of strength, vitality, and growth-power, which is + able to expend itself in this way without injury. That such is the + case is shown by the great abundance of most of the species which + possess these wonderful superfluities of plumage.... Why, in allied + species, the development of accessory plumes has taken different + forms, we are unable to say, except that it may be due to that + individual variability which has served as a starting-point for so + much of what seems to us strange in form, or fantastic in colour, + both in the animal and vegetable world[136]." + + [136] _Darwinism_, pp. 292-3. + +Here, again, one need only ask, How can such statements be reconciled +with the great dogma, "which is indeed a necessary deduction from the +theory of Natural Selection, namely, that none of the definite facts of +organic nature, no special organ, no characteristic form or marking can +exist, but which must now be, or once have been, _useful_"? Can it be +said that the plumes of a bird of paradise present "no characteristic +form," or the tail of a peacock "no characteristic marking"? Can it be +held that all the "fantastic colours," which Darwin attributes to sexual +selection, and all the "strange forms" in the vegetable world which +present no conceivable reference to adaptation, are to be ascribed to +"individual variability" without reference to utility, while at the same +time it is held, "as a necessary deduction from the theory of Natural +Selection," that _all_ specific characters must be "_useful_"? Or must +we not conclude that we have here a contradiction as direct as a +contradiction can well be[137]? + + [137] Since the above was written both Mr. Gulick and Professor + Lloyd Morgan have independently noticed the contradiction. + +Nor is it any more possible to reconcile these contradictory statements +by an indefinite extension of the term "correlation," than we found it +to be in the cases previously quoted. It might indeed be logically +possible, howsoever biologically absurd, to attribute the tail of a +peacock--with all its elaboration of structure and pattern of colour, +with all the drain that its large size and weight makes upon the vital +resources of the bird, with all the increased danger to which it exposes +the bird by rendering it more conspicuous, more easy of capture, &c.--to +correlation with some useful character peculiar to peacocks. But to say +that it is due to correlation with general "vitality," is merely to +discharge the doctrine of correlation of any assignable meaning. +Vitality, or "perfect adaptation to the conditions of existence," is +obviously a prime condition to the occurrence of a peacock's tail, as it +is to the occurrence of a peacock itself; but this is quite a different +thing from saying that the specific characters which are presented by a +peacock's tail, although useless in themselves, are correlated with some +other and useful specific characters of the same bird--as we saw in a +previous chapter with reference to secondary sexual characters in +general. Therefore, when Mr. Wallace comes to the obvious question why +it is that even in "allied species," which must be in equally "perfect +adaptation to the conditions of existence," there are no such "wonderful +superfluities of plumage," he falls back--as he previously fell back--on +whatever unknown _causes_ it may have been which produced the peacock's +tail, when the primary _condition_ to their operation has been furnished +by "complete success in the battle for life." + +I have quoted the above passages, not so much for the sake of exposing +fundamental inconsistencies on the part of an adversary, as for the sake +of observing that they constitute a much truer exposition of "Darwinism" +than do the contradictory views expressed in some other parts of the +work bearing that title. For even if characters of so much size and +elaboration as the tail of a peacock, the plumes of a bird of paradise +&c., are admitted to be due to non-utilitarian causes, much more must +innumerable other characters of incomparably less size and elaboration +be mere "superfluities." Without being actually deleterious, "a large +proportional number of specific characters," whose utility is not +apparent, must _a fortiori_ have been due to "individual variation," to +"general laws which determine the production" of such characters--or, in +short, to some causes other than natural selection. And this, I say, is +a doctrine much more in harmony with "Darwinism" than is the +contradictory doctrine which I am endeavouring to resist. + +But once again, and still more generally, after saying of "the delicate +tints of spring foliage, and the intense hues of autumn," that "as +colours they are unadaptive, and appear to have no more relation to the +well-being of plants themselves than do the colours of gems and +minerals," Mr. Wallace proceeds thus:-- + + "We may also include in the same category those algae and fungi + which have bright colours--the red snow of the Arctic regions, the + red, green, or purple seaweeds, the brilliant scarlet, yellow, + white or black agarics, and other fungi. All these colours are + probably the direct results of chemical composition or molecular + structure, and being thus normal products of the vegetable + organism, need no special explanation from our present point of + view; and the same remark will apply to the varied tints of the + bark of trunks, branches and twigs, which are often of various + shades of brown and green, or even vivid reds and yellows[138]." + + [138] _Darwinism_, p. 302. + +Here, as Mr. Gulick has already observed, "Mr. Wallace seems to admit +that instead of useless specific characters being unknown, they are so +common and so easily explained by 'the chemical constitution of the +organism' that they claim no special attention[139]." And whatever +answer Mr. Wallace may make to this criticism, I do not see how he is to +meet the point at present before us--namely, that, upon his own showing, +there are in nature numberless instances of "characters which are +useless without being hurtful," and which nevertheless present absolute +"constancy." If, in order to explain the contradiction, he should fall +back upon the principle of correlation, the case would not be in any way +improved. For, here again, if the term correlation were extended so as +to include "the chemical constitution or the molecular structure of the +organism," it would thereby be extended so as to discharge all Darwinian +significance from the term. + + [139] _American Journal of Science_, Vol. XL. art. I. on _The + Inconsistencies of Utilitarianism as the Exclusive Theory of + Organic Evolution_. + + +_Summary._ + +I will conclude this discussion of the Utility question by +recapitulating the main points in an order somewhat different from that +in which they have been presented in the foregoing chapters. Such a +variation may render their mutual connexions more apparent. But it is +only to the main points that allusion will here be made, and, in order +the better to show their independent character, I will separately number +them. + + * * * * * + +1. The doctrine of utility as universal, whether with respect to species +only or likewise with respect to specific characters, is confessedly an +_a priori_ doctrine, deduced by way of general reasoning from the theory +of natural selection. + +2. Being thus founded exclusively on grounds of deduction, the doctrine +cannot be combated by any appeal to facts. For this question is not one +of fact: it is a question of reasoning. The treatment of our subject +matter is logical: not biological. + +3. The doctrine is both universal and absolute. According to one form of +it _all_ species, and according to another form of it _all_ specific +characters, must _necessarily_ be due to the principle of utility. + +4. The doctrine in both its forms is deduced from a definition of the +theory of natural selection as a theory, and the sole theory, of the +origin of _species_; but, as Professor Huxley has already shown, it does +not really follow, even from this definition, that all specific +_characters_ must be "necessarily useful." Hence the two forms of the +doctrine, although coincident with regard to species, are at variance +with one another in respect of specific characters. Thus far, of course, +I agree with Professor Huxley; but if I have been successful in showing +that the above definition of the theory of natural selection is +logically fallacious, it follows that the doctrine in both its forms is +radically erroneous. The theory of natural selection is not, accurately +speaking, a theory of the origin of species: it is a theory of the +origin and cumulative development of adaptations, to whatever order of +taxonomic division these may happen to belong. Thus the premisses of the +deduction which we are considering collapse: the principle of utility is +shown not to have any other or further reference to species, or to +specific characters, than it has to fixed varieties, genera, families, +&c., or to the characters severally distinctive of each. + +5. But, quitting all such antecedent considerations, we next proceeded +to examine the doctrine _a posteriori_, taking the arguments which have +been advanced in favour of the doctrine, other than those which rest +upon the fallacious definition. These arguments, as presented by Mr. +Wallace, are two in number. + +First, it is represented that natural selection must occupy the whole +field, because no other principle of change can be allowed to operate in +the presence of natural selection. Now I fully agree that this statement +holds as regards any principle of change which is deleterious, but I +cannot agree that it does so as regards any such principle which is +merely neutral. No reason has ever been shown why natural selection +should interfere with "indifferent" characters--to adopt Professor +Huxley's term--supposing such to have been produced by any of the +agencies which we shall presently have to name. Therefore this +argument--or rather assertion--goes for nothing. + +Mr. Wallace's second argument is, that utility is the only principle +which can endow specific characters with their characteristic stability. +But this again is mere assertion. Moreover, it is assertion opposed +alike to common sense and to observable fact. It is opposed to common +sense, because it is obvious that any other principle would equally +confer stability on characters due to it, provided that its action is +constant, as Darwin expressly held. Again, this argument is opposed to +fact, because we know of thousands of cases where peculiar characters +are stable, which, nevertheless, cannot possibly be due to natural +selection. Of such are the Porto Santo rabbits, the niata cattle, the +ducks in St. James' Park, turkeys, dogs, horses, &c., and, in the case +of plants, wheat, cabbage, maize, &c., as well as all the hosts of +climatic varieties, both of animals and plants, in a state of nature. +Indeed, on taking a wide survey of the facts, we do not find that the +principle of utility is any better able to confer stability of character +than are many other principles, both known and unknown. Nay, it is +positively less able to do so than are some of these other principles. +Darwin gives two very probable reasons for this fact; but I need not +quote them a second time. It is enough to have seen that this argument +from stability or constancy is no less worthless than the previous one. +Yet these are the only two arguments of a corroborative kind which Mr. +Wallace adduces whereby to sustain his "necessary deduction." + +6. At this point, therefore, it may well seem that we need not have +troubled ourselves any further with a generalization which does not +appear to have anything to support it. And to this view of the case I +should myself agree, were it not that many naturalists now entertain the +doctrine as an essential article of their Darwinian creed. Hence, I +proceeded to adduce considerations _per contra_. + +Seeing that the doctrine in question can only rest on the assumption +that there is no cause other than natural selection which is capable of +originating any single species--if not even so much as any single +specific character--I began by examining this assumption. It was shown +first that, on merely antecedent grounds, the assumption is "infinitely +precarious." There is absolutely no justification for the statement that +in all the varied and complex processes of organic nature natural +selection is the only possible cause of specific change. But, apart +altogether from this _a priori_ refutation of the dogma, our analysis +went on to show that, in point of actual fact, there are not a few +well-known causes of high generality, which, while having no connexion +with the principle of utility, are demonstrably capable of originating +species and specific characters--if by "species" and "specific +characters" we are to understand organic types which are ranked as +species, and characters which are described as diagnostic of species. +Such causes I grouped under five different headings, viz. Climate, Food, +Sexual Selection, Isolation, and Laws of Growth. Sexual Selection and +Isolation are, indeed, repudiated by Mr. Wallace; but, in common I +believe with all biologists, he accepts the other three groups of causes +as fully adequate to produce such kinds and degrees of modification as +are taken to constitute specific distinction. And this is amply +sufficient for our present purposes. Besides, under the head of Sexual +Selection, it does not signify in the present connexion whether or not +we accept Darwin's theory on this subject. For, in any case, the facts +of secondary sexual characters are indisputable: these characters are, +for the most part, specific characters: and they cannot be explained by +the principle of utility. Even Mr. Wallace does not attempt to do so; +and the explanation which he does give is clearly incompatible with his +doctrine touching the necessarily life-serving value of all specific +characters. Lastly, the same has to be said of the Laws of Growth. For +we have just seen that on the grounds of this principle likewise Mr. +Wallace abandons the doctrine in question. As regards Isolation, much +more remains to be said in the ensuing portion of this work, while, as +regards Climatic Variation, there are literally innumerable cases where +changes of specific type are known to have been caused by this means. + +7. To the latter class of cases, however, it will be objected that these +changes of specific type, although no doubt sufficiently "stable" so +long as the changed conditions remain constant, are found by experiment +not to be hereditary; and this clearly makes all the difference between +a true specific change and a merely fictitious appearance of it. + +Well, in the first place, this objection can have reference only to the +first two of the five principles above stated. It can have no reference +to the last three, because of these heredity constitutes the very +foundation. This consideration ought to be borne in mind throughout. But +now, in the second place, even as regards changes produced by climate +and food, the reply is nugatory. And this for three reasons, as follows. + +(_a_) No one is thus far entitled to conclude against the possible +transmission of acquired characters; and, so long as there is even so +much as a possibility of climatic (or any other admittedly +non-utilitarian) variations becoming in this way hereditary, the reply +before us merely begs the question. + +(_b_) Even supposing, for the sake of argument, that acquired characters +can never in any case become congenital, there remains the strong +probability--sanctioned as such even by Weismann--that changed +conditions of life may not unfrequently act upon the material of +heredity itself, thus giving rise to specific changes which are from +the first congenital, though not utilitarian. Indeed, there are not a +few facts (Hoffmann's plants, Weismann's butterflies, &c.), which can +only be explained either in this way, or as above (_a_). And in the +present connexion it is immaterial which of these alternative +explanations we choose to adopt, seeing that they equally refute our +opponents' objection. And not only do these considerations--(_a_) and +(_b_)--refute this particular objection; they overturn on new and +independent grounds the whole of our opponents' generalization. For the +generalization is, that the principle of utility, acting through natural +selection, is "necessarily" the sole principle which can be concerned in +hereditary changes of specific type. But here we perceive both a +possibility (_a_) and a probability (_b_), if not indeed a certainty, +that quite other principles have been largely concerned in the +production of such changes. + +(_c_) Altogether apart from these considerations, there remains a much +more important one. For the objection that fixed--or "stable"--climatic +varieties differ from true species in not being subject to heredity, +raises the question--What are we to understand by a "species"? This +question, which was thus far purposely left in abeyance, had now to be +dealt with seriously. For it would clearly be irrational in our +opponents to make this highly important generalization with regard to +species and specific characters, unless they are prepared to tell us +what they mean by species, and therefore by characters as specific. In +as far as there is any ambiguity on this point it makes entirely for +our side in the debate, because even any small degree of uncertainty +with regard to it would render the generalization in question +proportionally unsound. Yet it is notorious that no word in existence is +more vague, or more impossible to define, than the word "species." The +very same men who at one time pronounce their great generalization with +regard to species, at another time asseverate that "a species is not a +definite entity," but a merely abstract term, serving to denote this +that and the other organic type, which this that and the other +systematist regards as deserving such a title. Moreover it is +acknowledged that systematists differ among themselves to a wide extent +as to the kinds and degrees of peculiarity which entitle a given form to +a specific rank. Even in the same department of systematic work much +depends on merely individual taste, while in different departments +widely different standards of delimination are in vogue. Hence, our +_reductio ad absurdum_ consists in this--that whether a given form is to +be regarded as necessarily due to natural selection, and whether all its +distinctive characters are to be regarded as necessarily utilitarian +characters, will often depend on whether it has been described by +naturalist A or by naturalist B. There is no one criterion--there is not +even any one set of criteria--agreed upon by naturalists for the +construction of specific types. In particular, as regards the principle +of heredity, it is not known of one named species in twenty--probably +not in a hundred--whether its diagnostic characters are hereditary +characters; while, on the other hand, even in cases where experiment has +proved "constant varieties" to be hereditary--and even also +cross-sterile with allied varieties--it is only some three or four +living botanists who for these reasons advocate the elevation of such +varieties to the rank of species. In short, as we are not engaged on any +abstract question touching the principles on which species ought to have +been constituted by their makers, but upon the actual manner in which +they have been, the criterion of heredity must needs be disregarded in +the present discussion, as it has been in the work of systematists. And +the result of this is, that any objection to our introducing the facts +of climatic variation in the present discussion is excluded. In +particular, so far as any question of heredity is concerned, all these +facts are as assuredly as they are cogently relevant. It is perfectly +certain that there is "a large proportional number" of named +species--particularly of plants--which further investigation would +resolve into climatic varieties. With the advance of knowledge, "bad +species" are always increasing at the expense of "good species," so that +we are now justified in concluding with Kerner, Häckel, and other +naturalists best qualified to speak on this subject, that if we could +know as much about the past history and present relations of the +remaining good species as we do about the bad, all the former, without +exception, would become resolved into the latter. In point of fact, and +apart altogether from the inductive experience on which this conclusion +is based, the conclusion follows "as a necessary deduction" from the +general theory of descent. For this theory essentially consists in +supposing either the past or the present existence of intermediate +varietal forms in all cases, with the consequence that "good species" +serve merely to mark _lacunae_ in our knowledge of what is everywhere a +finely graduated process of transmutation. Hence, if we place this +unquestionably "necessary deduction" from the general theory of descent +side by side with the alleged "necessary deduction" from the theory of +natural selection, we cannot avoid the following absurdity--Whether or +not a given form is to be regarded as necessarily due to natural +selection, and all its characters necessarily utilitarian, is to be +determined, and determined solely, by the mere accident of our having +found, or not having found, either in a living or in a fossil state, its +varietal ancestry. + +8. But this leads us to consider the final and crowning incongruities +which have been dealt with in the present chapter. For here we have +seen, not only that our opponents thus draw a hard and fast line between +"varieties" and "species" in regard to "necessary origin" and "necessary +utility," but that they further draw a similar line between "species" +and "genera" in the same respects. Yet, in accordance with the general +theory of evolution, it is plainly as impossible to draw any such line +in the one case as it is to do so in the other. Just as fixed varieties +are what Darwin called "incipient species," so are species incipient +genera, genera incipient families, and so on. Evolutionists must believe +that the process of evolution is everywhere the same. Nevertheless, +while admitting all this, the school of Huxley contradicts itself by +alleging some unintelligible exception in the case of "species," while +the school of Wallace presses this exception so as to embrace "specific +characters." Indeed Mr. Wallace, while maintaining that all specific +characters must necessarily be useful, maintains at the same time that +any number of varietal characters on the one hand, and a good half of +generic characters on the other, are probably useless. Thus he +contradicts his argument from the "constancy of specific characters" +(seeing that generic characters are still more constant), as later on we +saw that he contradicts his deductive generalization touching their +necessary utility, by giving a non-utilitarian explanation of whole +multitudes of specific characters. I need not, however, again go over +the ground so recently traversed; but will conclude by once more +recurring to the only explanation which I have been able to devise of +the otherwise inexplicable fact, that in regard to this subject so many +naturalists still continue to entangle themselves in the meshes of +absurdity and contradiction. + + * * * * * + +The only conceivable explanation is, that these naturalists have not yet +wholly divested themselves of the special creation theory. Although +professing to have discarded the belief that "species" are "definite +entities," differing in kind from "varieties" on the one hand and from +"genera" on the other, these writers are still imbued with a vague +survival of that belief. They well know it to belong to the very essence +of their new theory that "species" are but "pronounced varieties," or, +should we prefer it, "incipient genera"; but still they cannot +altogether escape the pre-Darwinian conception of species as organic +units, whose single mode of origin need not extend to other taxonomic +groups, and whose characters therefore present some exceptional +significance to the scientific naturalist. So to speak, such divinity +doth still hedge a species, that even in the very act of declaring it +but an idol of their own creation, these naturalists bow before their +fetish as something that is unique--differing alike in its origin and in +its characters from the varieties beneath and the genera above. The +consequence is that they have endeavoured to reconcile these +incompatible ideas by substituting the principle of natural selection +for that of super-natural creation, where the particular case of +"species" is concerned. In this way, it vaguely seems to them, they are +able to save the doctrine of some one mode of origin as appertaining to +species, which need not "necessarily" appertain to any other taxonomic +division. All other such divisions they regard, with their pre-Darwinian +forefathers, as merely artificial constructions; but, likewise with +these forefathers, they look upon species as natural divisions, proved +to be such by a single and necessary mode of origin. Hence, Mr. Wallace +expressly defines a species with reference to this single and necessary +mode of origin (_see_ above, p. 235), although he must be well aware +that there is no better, or more frequent, proof of it in the case of +species, than there is in that of somewhat less pronounced types on the +one hand (fixed varieties), or of more pronounced types on the other +(genera, families, &c.). Hence, also, the theory of natural selection is +defined as _par excellence_ a theory of the origin of species; it is +taken as applying to the particular case of the origin of species in a +peculiarly stringent manner, or in a manner which does not apply to the +origin of any other groups. And I believe that an important accessory +reason of the continuance of this view for more than thirty years after +the publication of the _Origin of Species by means of Natural +Selection_, is to be found in the title of that work. "Natural +Selection" has thus become verbally associated with "Origin of Species," +till it is thoughtlessly felt that, in some way or another, natural +selection must have a peculiar reference to those artificially +delineated forms which stand anywhere between a fixed variety and a +so-called genus. This verbal association has no doubt had the effect of +still further preserving the traditional halo of mystery which clings to +the idea of a "species." Hence it comes that the title which Darwin +chose--and, looking to the circumstances of the time, wisely chose--for +his great work, has subsequently had the effect of fostering the very +idea which it was the object of that work to dissipate, namely, that +species are peculiar entities, which differ more or less in origin or +kind from all other taxonomic groups. The full title of this work +is--_The Origin of Species by means of Natural Selection: or the +Preservation of Favoured Races in the Struggle for Life_. Now, supposing +that instead of this its author had chosen some such title as the +following:--_The Origin of Organic Types by means of Adaptive Evolution: +or Survival of the Fittest Forms in the Struggle for Life_. Of course +this would have been a bad substitute from various points of view; but +could any objection have been urged against it from our present point of +view? I do not see that there could. Yet, if such had been the title, I +have little doubt that we should never have heard of those great +generalizations with regard to species and specific characters, the +futility of which it has been the object of these chapters to expose. + + * * * * * + +In conclusion, it only remains to reiterate that in thus combating what +appears to me plainly erroneous deductions from the theory of natural +selection, I am in no wise combating that theory itself. On the +contrary, I hope that I am rendering it no unimportant service by +endeavouring to relieve it of a parasitic growth--an accretion of false +logic. Regarding as I do the theory of natural selection as, primarily, +a theory of the origin (or cumulative development) of adaptations, I see +in merely non-adaptive characters--be they "specific" or other--a +comparatively insignificant class of phenomena, which may be due to a +great variety of incidental causes, without any further reference to the +master-principle of natural selection than that in the presence of this +principle none of these non-adaptive characters can be actively +deleterious. But that there may be "any number of indifferent +characters" it is no part of the theory of natural selection to deny; +and all attempts to foist upon it _a priori_ "deductions" opposed alike +to the facts of nature and to the logic of the case, can only act to the +detriment of the great generalization which was expressly guarded from +such fallacies by the ever-careful judgement of Darwin. + + + + +APPENDICES AND NOTES + + + + +APPENDIX I. + +ON PANMIXIA. + + +There are several points of considerable theoretical importance +connected with Panmixia, which were omitted from the text, in order to +avoid distracting attention from the main issue which is there under +consideration. These side issues may now be appropriately presented in +the form in which they were published in _Nature_, March 13, 1890[140]. +After stating, in almost the same words, what has already been said in +Chapter X, this paper proceeds, with the exception of a few verbal +alterations, as follows. + + [140] Vol. xli. p. 438. + + "There is, however, one respect in which Professor Weismann's + statement of the principle of panmixia differs from that which was + considered by Mr. Darwin; and it is this difference of + statement--which amounts to an important difference of theory--that + I now wish to discuss. + + "The difference in question is, that while Professor Weismann + believes the cessation of selection to be capable of inducing + degeneration down to the almost complete disappearance of a + rudimentary organ, I have argued that, _unless assisted by some + other principle_, it can at most only reduce the degenerating organ + to considerably above one-half its original size--or probably not + through so much as one-quarter. The ground of this argument (which + is given in detail in the _Nature_ articles of 1873-1874) is, that + panmixia depends for its action upon fortuitous variations round an + ever-diminishing average--the average thus diminishing because it + is no longer _sustained_ by natural selection. But although no + longer sustained by _natural selection_, it does continue to be + sustained by _heredity_; and therefore, as long as the force of + heredity persists unimpaired, fortuitous variations alone--or + variation which is no longer controlled by natural + selection--cannot reduce the dwindling organ to so much as one-half + of its original size; indeed, as above foreshadowed, the balance + between the positive force of heredity and the negative effects of + promiscuous variability will most likely be arrived at above the + middle line thus indicated. Only if for any reason the force of + heredity begins to fail can the average round which the cessation + of selection works become a progressively diminishing average. In + other words, so long as the original force of heredity as regards + the useless organ remains unimpaired, the mere withdrawal of + selection cannot reduce the organ much below the level of + efficiency above which it was previously _maintained_ by the + _presence_ of selection. If we take this level to be 80 or 90 per + cent. of the original size, cessation of selection will reduce the + organ through the 10 or 20 per cent., and there leave it + fluctuating about this average, unless for any reason the force of + heredity begins to fail--in which case, of course, the average will + progressively fall in proportion to the progressive weakening of + this force. + + "Now, according to my views, the force of heredity under such + circumstances is always bound to fail, and this for two reasons. In + the first place, it must usually happen that when an organ becomes + useless, natural selection as regards that organ will not only + _cease_, but become _reversed_. For the organ is now absorbing + nutriment, causing weight, occupying space, and so on, _uselessly_. + Hence, even if it be not also a source of actual danger, 'economy + of growth' will determine a reversal of selection against an organ + which is now not merely useless, but deleterious. And this + degenerating influence of the reversal of selection will throughout + be assisted by the cessation of selection, which will now be always + acting round a continuously sinking average. Nevertheless, a point + of balance will eventually be reached in this case, just as it was + in the previous case where the cessation of selection was supposed + to be working alone. For, where the reversal of selection has + reduced the diminishing organ to so minute a size that its presence + is no longer a source of detriment to the organism, the cessation + of selection will carry the reduction a small degree further; and + then the organ will remain as a 'rudiment.' And so it will remain + permanently, unless there be some further reason why the still + remaining force of heredity should be abolished. This further (or + second) reason I found in the consideration that, however enduring + we may suppose the force of heredity to be, we cannot suppose that + it is actually everlasting; and, therefore, that we may reasonably + attribute the eventual disappearance of rudimentary organs to the + eventual failure of heredity itself. In support of this view there + is the fact that rudimentary organs, although very persistent, are + not everlasting. That they should be very persistent is what we + should expect, if the hold which heredity has upon them is great in + proportion to the time during which they were originally useful, + and thus firmly stamped upon the organization by natural selection + causing them to be strongly inherited in the first instance. For + example, we might expect that it would be more difficult finally to + eradicate the rudiment of a wing than the rudiment of a feather; + and accordingly we find it a general rule that long-enduring + rudiments are rudiments of organs distinctive of the higher + taxonomic divisions--i.e. of organs which were longest in building + up, and therefore longest sustained in a state of working + efficiency. + + "Thus, upon the whole, my view of the facts of degeneration remains + the same as it was when first published in these columns seventeen + years ago, and may be summarized as follows. + + "The cessation of selection when working alone (as it probably does + during the first centuries of its action upon structures or colours + which do not entail any danger to, or perceptible drain upon, the + nutritive resources of the organism) cannot cause degeneration + below, probably, some 10 to 20 per cent. But if from the first the + cessation of selection has been assisted by the _reversal_ of + selection (on account of the degenerating structure having + originally been of a size sufficient to entail a perceptible drain + on the nutritive resources of the organism, having now become a + source of danger, and so forth), the two principles acting together + will continue to reduce the ever-diminishing structure down to the + point at which its presence is no longer a perceptible disadvantage + to the species. When that point is reached, the reversal of + selection will terminate, and the cessation of selection will not + then be able of itself to reduce the organ through more than at + most a very few further percentages of its original size. But, + after this point has been reached, the now total absence of + selection, either for or against the organ, will sooner or later + entail this further and most important consequence, a failure of + heredity as regards the organ. So long as the organ was of use, its + efficiency was constantly _maintained_ by the _presence_ of + selection--which is merely another way of saying that selection was + constantly maintaining the force of heredity as regards that organ. + But as soon as the organ ceased to be of use, selection ceased to + maintain the force of heredity; and thus, sooner or later, that + force began to waver or fade. Now it is this wavering or fading of + the force of heredity, thus originally due to the cessation of + selection, that in turn co-operates with the still continued + cessation of selection in reducing the structure below the level + where its reduction was left by the actual reversal of selection. + So that from that level downwards the cessation of selection, and + the consequent failing of heredity, act and react in their common + work of causing obsolescence. In the case of newly added + characters, the force of heredity will be less than in that of more + anciently added characters; and thus we can understand the long + endurance of 'vestiges' characteristic of the higher taxonomic + divisions, as compared with those characteristic of the lower. But + in all cases, if time enough be allowed under the cessation of + selection, the force of heredity will eventually fall to zero, when + the hitherto obsolescent structure will finally become obsolete. In + cases of newly added and comparatively trivial characters, with + regard to which reversal of selection is not likely to take place + (e.g. slight differences of colour between allied species), + cessation of selection is likely to be very soon assisted by a + failure in the force of heredity; seeing that such newly added + characters will not be so strongly inherited as are the more + ancient characters distinctive of higher taxonomic groups. + + "Let us now turn to Weismann's view of degeneration. First of all, + he has omitted to perceive that 'panmixia' alone (if unassisted + either by reversed selection or an inherent diminishing of the + force of heredity) cannot reduce a functionless organ to the + condition of a _rudiment_. Therefore he everywhere represents + panmixia (or the mere _cessation_ of selection) as of itself + sufficient to cause degeneration, say from 100 to 5, instead of + from 100 to 90 or 80, which, for the reasons above given, appeared + (and still appears) to me about the most that this principle can + accomplish, so long as the original force of heredity continues + unimpaired. No doubt we have here what must be regarded as a mere + oversight on the part of Professor Weismann; but the oversight is + rendered remarkable by the fact that he _does_ invoke the aid of + reversed selection _in order to explain the final disappearance of + a rudiment_. Yet it is self-evident that the reversal of selection + must be much more active during the initial than during the final + stages of degeneration, seeing that, _ex hypothesi_, the greater + the degree of reduction which has been attained the less must be + the detriment arising from any useless expenditure of nutrition, + &c. + + "And this leads me to a second oversight in Professor Weismann's + statement, which is of more importance than the first. For the + place at which he does invoke the assistance of reversed selection + is exactly the place at which reversed selection must necessarily + have ceased to act. This place, as already explained, is where an + obsolescent organ has become rudimentary, or, as above supposed, + reduced to 5 per cent. of its original size; and the reason why he + invokes the aid of reversed selection at this place is in order to + save his doctrine of 'the stability of germ-plasm.' That the force + of heredity should finally become exhausted if no longer + _maintained_ by the _presence_ of selection, is what Darwin's + theory of perishable gemmules would lead us to expect, while such a + fact would be fatal to Weismann's theory of an imperishable + germ-plasm. Therefore he seeks to explain the eventual failure of + heredity (which is certainly a fact) by supposing that after the + point at which the cessation of selection alone can no longer act + (and which his first oversight has placed some 80 per cent. too + low), the reversal of selection will begin to act directly against + the force of heredity as regards the diminishing organ, until such + direct action of reversed selection will have removed the organ + altogether. Or, in his own words, 'The complete disappearance of a + rudimentary organ can only take place by the operation of natural + selection; this principle will lead to its diminution, inasmuch as + the disappearing structure takes the place and the nutriment of + other useful and important organs.' That is to say, the + rudimentary organ finally disappears, not because the force of + heredity is finally exhausted, but because natural selection has + begun to utilize this force against the continuance of the + organ--always picking out those congenital variations of the organ + which are of smallest size, and thus, by its now _reversed_ action, + _reversing_ the force of heredity as regards the organ. + + "Now the oversight here is in not perceiving that the smaller the + disappearing structure becomes, the less hold must 'this principle' + of reversed selection retain upon it. As above observed, during the + earlier stages of reduction (or while co-operating with the + cessation of selection) the reversal of selection will be at its + _maximum_ of efficiency; and, as the process of diminution + continues, a point must eventually be reached at which the reversal + of selection can no longer act. Take the original mass of a now + obsolescent organ in relation to that of the entire organism of + which it then formed a part to be represented by the ratio 1:100. + For the sake of argument we may assume that the mass of the + organism has throughout remained constant, and that by 'mass' in + both cases is meant capacity for absorbing nutriment, causing + weight, occupying space, and so forth. Now, we may further assume + that when the mass of the organ stood to that of its organism in + the ratio of 1:100, natural selection was strongly reversed with + respect to the organ. But when this ratio fell to 1:1000, the + activity of such reversal must have become enormously diminished, + even if it still continued to exercise any influence at all. For we + must remember, on the one hand, that the reversal of selection can + only act as long as the presence of a diminishing organ continues + to be so injurious that variations in its size are matters of life + and death in the struggle for existence; and, on the other hand, + that natural selection in the case of the diminishing organ does + not have reference to the presence and the absence of the organ, + but only to such variations in its mass as any given generation may + supply. Now, the process of reduction does not end even at 1:1000. + It goes on to 1:10,000, and eventually 1:∞. Consequently, however + great our faith in natural selection may be, a point must + eventually come for all of us at which we can no longer believe + that the reduction of an obsolescent organ is due to reversed + selection. And I cannot doubt that if Professor Weismann had + sufficiently considered the matter, he would not have committed + himself to the statement that 'the complete disappearance of a + rudimentary organ can only take place by the operation of natural + selection.' + + "According to my view, the complete disappearance of a rudimentary + organ can only take place by the _cessation_ of natural selection, + which permits the eventual exhaustion of heredity, when heredity is + thus simply left to itself. During all the earlier stages of + reduction, the cessation of selection was assisted in its work by + the reversal of selection; but when the rudiment became too small + for such assistance any longer to be supplied, the rudiment + persisted in that greatly reduced condition until the force of + heredity with regard to it was eventually worn out. This appears to + me, as it appeared in 1873, the only reasonable conclusion that can + be drawn from the facts. And it is because this conclusion is fatal + to Professor Weismann's doctrine of the permanent 'stability' of + germ-plasm, while quite in accordance with all theories which + belong to the family of pangenesis, that I deem the facts of + degeneration of great importance as tests between these rival + interpretations of the facts of heredity. It is on this account + that I have occupied so much space with the foregoing discussion; + and I shall be glad to ascertain whether any of the followers of + Professor Weismann are able to controvert these views. + + "GEORGE J. ROMANES." + + "P.S.--Since the above article was sent in, Professor Weismann has + published in these columns (February 6) his reply to a criticism by + Professor Vines (October 24, 1889). In this reply he appears to + have considerably modified his views on the theory of degeneration; + for while in his Essays he says (as in the passage above quoted) + that 'the complete disappearance of a rudimentary organ can only + take place by the operation of natural selection'--i.e. only by the + _reversal_ of selection,--in his reply to Professor Vines he says, + 'I believe that I have proved that organs no longer in use become + rudimentary, and must finally disappear, solely by 'panmixia'; not + through the direct action of disuse, but because natural selection + no longer sustains their standard structure'--i.e. solely by the + _cessation_ of selection. Obviously, there is here a flat + contradiction. If Professor Weismann now believes that a + rudimentary organ 'must finally disappear _solely_' through the + _withdrawal_ of selection, he has abandoned his previous belief + that 'the complete disappearance of a rudimentary organ can _only_ + take place by the _operation_ of selection.' And this change of + belief on his part is a matter of the highest importance to his + system of theories as a whole, since it betokens a surrender of his + doctrine of the 'stability' of germ-plasm--or of the virtually + everlasting persistence of the force of heredity, and the + consequent necessity for a reversal of this force itself (by + natural selection placing its premium on _minus_ instead of on + _plus_ variations), in order that a rudimentary organ should + finally disappear. In other words, it now seems he no longer + believes that the force of heredity in one direction (that of + sustaining a rudimentary organ) can only be abolished by the active + influence of natural selection determining this force in the + opposite direction (that of removing a rudimentary organ). It seems + he now believes that the force of heredity, if merely left to + itself by the withdrawal of natural selection altogether, will + sooner or later become exhausted through the mere lapse of time. + This, of course, is my own theory of the matter as originally + published in these columns; but I do not see how it is to be + reconciled with Professor Weismann's doctrine of so high a degree + of stability on the part of germ-plasm, that we must look to the + Protozoa and the Protophyta for the original source of congenital + variations as now exhibited by the Metazoa and Metaphyta. + Nevertheless, and so far as the philosophy of degeneration is + concerned, I shall be very glad if (as it now appears) Professor + Weismann's more recent contemplation has brought his principle of + panmixia into exact coincidence with that of my cessation of + selection." + +Before passing on it may here be noted that, to any one who believes in +the inheritance of acquired characters, there is open yet another +hypothetical cause of degeneration, and one to which the final +disappearance of vestigial organs may be attributed. Roux has shown in +his work on _The Struggle for Existence between Parts of an Organism_ +that the principle of selection must operate in every constituent +tissue, and as between every constituent cell of which an organism is +composed. Now, if an organ falls into disuse, its constituent cells +become worsted in their struggles with other cells in the organism. +Hence, degeneration of the disused organ may progressively increase, +quite independently of any struggle for existence on the part of the +organism as a whole. Consequently, degeneration may proceed without any +reference to the principle of "economized nutrition"; and, if it does +so, and if the effects of its doing so are transmitted from generation +to generation, the disused organ will finally disappear by means of +Roux's principle. + +The long communication above quoted led to a still longer correspondence +in the pages of _Nature_. For Professor Ray Lankester wrote[141] to +impugn the doctrine of panmixia, or cessation of selection, _in toto_, +arguing with much insistence that "cessation of selection must be +supplemented by economy of growth in order to produce the results +attributed to panmixia." In other words, he denied that panmixia alone +can cause degeneration in any degree at all; at most, he said, it can be +but "a condition," or "a state," which occurs when an organ or part +ceases to be useful, and therefore falls under the degenerating +influence of active causes, such as economy of nutrition. Or, in yet +other words, he refused to recognize that any degenerative process can +be due to natural selection as merely withdrawn: only when, besides +being _withdrawn_, natural selection is _reversed_, did he regard a +degenerative process as possible. As a result of the correspondence, +however, he eventually[142] agreed that, if the "birth-mean" of an +organ, in respect either of size or complexity of structure, be lower +than the "selection-mean" while the organ is useful (a fact which he +does not dispute); then, if the organ ceases to be useful, it will +degenerate by the withdrawal of selection alone. Which, of course, is +merely a re-statement of the doctrine of panmixia, or cessation of +selection, in somewhat varied terminology--provided that the birth-mean +be taken over a number of generations, or not only over a few following +the selection-mean of the structure while still in its highest state of +efficiency. For the sake of brevity I will hereafter speak of these "few +following" generations by the term of "first generations." + + [141] _Nature_, vol. xli. p. 486. + + [142] _Ibid._ vol. xlii. p. 52. + +It remains to consider the views of Professor Lloyd Morgan upon the +subject. In my opinion he is the shrewdest, as well as the most logical +critic that we have in the field of Darwinian speculation; therefore, if +possible, I should like to arrive at a full agreement with him upon this +matter. His latest utterance with regard to it is as follows:-- + + "To account for the diminution of organs or structures no longer of + use, apart from any inherited effects of disuse, Mr. Romanes has + invoked the Cessation of Selection; and Mr. Francis Galton has, in + another connexion, summarized the effects of this cessation of + selection in the convenient phrase 'Regression to Mediocrity.' This + is the Panmixia of Professor Weismann and his followers; but the + phrase regression to mediocrity through the cessation of selection + appears to me preferable. It is clear that so long as any organ or + structure is subject to natural selection through elimination, it + is, if not actually undergoing improvement, kept at a high standard + of efficiency through the elimination of all those individuals in + which the organ in question falls below the required standard. But + if, from change in the environment or any other cause, the + character in question ceases to be subject to selection, + elimination no longer takes place, and the high standard will no + longer be maintained. There will be reversion to mediocrity. The + probable amount of this reversion is at present a matter under + discussion[143]." + + [143] _Presidential Address to the Bristol Naturalists' Society_, + 1891. + +So far, then, Professor Lloyd Morgan is in complete agreement with +previous writers upon the subject. He does not doubt that the cessation +of selection must always be a cause of degeneration: the only question +is as to the _potency_ of this cause, or the _amount_ of degeneration +which it is capable of effecting. + +Taking, first, the case of bulk or size of an organ, as distinguished +from its organization or complexity, we have seen that Weismann +represents the cessation of selection--even if working quite alone, or +without any assistance from the reversal of selection--to be capable of +reducing a fully developed organ to the state of a rudiment, or even, if +we take his most recent view, of abolishing the organ _in toto_. + +Professor Lloyd Morgan, on the other hand, does not think that the +cessation of selection alone can cause reduction further than the level +of "mediocrity" in the first generations--or, which is much the same +thing, further than the difference between the "birth-mean" and the +"selection-mean" of the first generations. This amount of reduction he +puts at 5 per cent., as "a very liberal estimate." + +Here, then, we have three estimates of the amount of degeneration which +can be produced by panmixia alone, where mere size or bulk of an organ +is concerned--say, 3 to 5 per cent., 10 to 20 per cent., and 95 per +cent. to 0. At first sight, these differences appear simply ludicrous; +but on seeking for the reasons of them, we find that they are due to +different views touching the manner in which panmixia operates. The +oversights which have led to Weismann's extremely high estimate have +already been stated. The reason of the difference between the extremely +low estimate of Professor Lloyd Morgan, as compared with my own +intermediate one, is, that he supposes the power of panmixia to become +exhausted as soon as the level of mediocrity of the first generations +has become the general level in succeeding generations. In my view, +however, the level of mediocrity is itself a sinking level in +successive generations, with the result that there is no reason why the +reducing power of panmixia should ever become exhausted, save that the +more reduction it effects the greater is the force of heredity which +remains to be overcome, as previously explained. Thus the only question +between Professor Lloyd Morgan and myself is--Does the level of +mediocrity fall in successive generations under the cessation of +selection, or does it remain permanently where it used to be under the +presence of selection? Does the "birth-mean" remain constant throughout +any number of generations, notwithstanding that the sustaining influence +of selection has been withdrawn; or does it progressively sink as a +consequence of such withdrawal? + +In order to answer this question we had better begin by considering now +the case of organization of structure, as distinguished from mere size +of structure. Take any case where a complex organ--such as a compound +eye--has been slowly elaborated by natural selection, and is it not +self-evident that, when natural selection is withdrawn, the complex +structure will deteriorate? In other words, the level of mediocrity, say +in the hundred thousandth generation after the sustaining influence of +natural selection has been withdrawn, will not be so high as it was in +the first generations. For, by hypothesis, there is now no longer any +elimination of unfavourable variations, which may therefore perpetuate +themselves as regards any of the parts of this highly complex mechanism; +so that it is only a matter of time when the mechanism must become +disintegrated. I can scarcely suppose that any one who considers the +subject will question this statement, and therefore I will not say +anything that might be said in the way of substantiating it. But, if the +statement be assented to, it follows that there is no need to look for +any cause of deterioration, further than the withdrawal of selection--or +cessation of the principle which (as we are supposing) had hitherto +been the sole means of maintaining efficient harmony among all the +independently variable parts of the highly complex structure. + +Now, I hold that the same thing is true, though in a lesser degree, as +regards degeneration of size. That there is no difference _in kind_ +between the two cases, Professor Lloyd Morgan implicitly allows; for +what he says is-- + + "In any long-established character, such as wing-power in birds, + brain-development, the eyes of crustacea, &c., no shortcomer in + these respects would have been permitted by natural selection to + transmit his shortcomings for hundreds of generations. All tendency + to such shortcomings would, one would suppose, have been bred out + of the race. If after this long process of selection there still + remains a strong tendency to deterioration, this tendency demands + an explanation[144]." + + [144] _Presidential Address to the Bristol Naturalists' Society_, + 1891. + +Here, then, deterioration as to size of structure (wings of birds), and +deterioration as to complexity of structure (brain and eyes) are +expressly put upon the same footing. Therefore, if in the latter case +the "tendency to deterioration" does not "demand an explanation," beyond +the fact that the hitherto maintaining influence has been withdrawn, +neither is any such further explanation demanded in the former case. +Which is exactly my own view of the matter. It is also Mr. Galton's +view. For although, in the passage formerly quoted, Professor Lloyd +Morgan appears to think that by the phrase "Regression to Mediocrity" +Mr. Galton means to indicate that panmixia can cause degeneration only +as far as the mediocrity level of the first generations, this, in point +of fact, is not what Galton means, nor is it what he says. The phrase in +question occurs "in another connexion," and, indeed, in a different +publication. But where he expressly alludes to the cessation of +selection, this is what he says. The italics are mine. + + "A special cause may be assigned for the effects of use in causing + hereditary _atrophy_ of disused parts. It has already been shown + that all exceptionally developed organs tend to deteriorate: + consequently, those that are not _protected_ by selection will + _dwindle_. The level of muscular efficiency in the wing of a + strongly flying bird [curiously enough, the same case that is + chosen by Professor Lloyd Morgan to illustrate his opposite view], + is like the level of water in the leaky vessel of a Danaid, only + secured to the race by _constant effort_, so to speak. _Let the + effort be relaxed ever so little, and the level immediately + falls[145]._" + + [145] _A Theory of Heredity_, Journal of Anthropological Institute, + 1875. Vol. v. p. 345. + +I take it, then, that the burden of proof lies with Professor Lloyd +Morgan to show why the withdrawal of selection is _not_ sufficient to +account for degeneration any further than the mediocrity-level in the +former presence of selection. Why does "the strong tendency[146] to +deterioration demand an explanation," further than the fact that when +all variations below the average in every generation are allowed to +survive, they must gradually lower the average itself through a series +of generations? To answer that any such tendency "would have been bred +out of the race" by the previous action of selection, is to suppose that +the function of selection is at an end when once it has built up a +structure to the highest point of working efficiency,--that the presence +of selection is no longer required to _maintain_ the structure at that +point. But it is enough to ask in reply--Why, under the cessation of +selection, does _complexity_ of structure degenerate so much more +rapidly than _size_ of structure? Why is it, for instance, that "the +eyes of crustacea" in dark caves have entirely disappeared, while their +foot-stalks (when originally present) still remain? Can it be maintained +that "for hundreds of generations" natural selection was more intent on +developing the foot-stalks than the eyes which were mounted upon +them--so that while the latter were left by selection with "a strong +tendency to deterioration," the former have had this tendency "bred out +in the race"[147]? + + [146] No one has supposed that the tendency need be "strong": it has + only to be persistent. + + [147] Of course it must be observed that degeneration of complexity + involves also degeneration of size, so that a more correct + statement of the case would be--Why, under the cessation of + selection, does an organ of extreme complexity degenerate much + more rapidly than one of much less complexity? For example, + under domestication the brains of rabbits and ducks appear to + have been reduced in some cases by as much as 50 per cent. + (Darwin, and Sir J. Crichton Browne.) But if it is possible to + attribute this effect--or part of it--to an artificial + selection of stupid animals, I give in the text an example + occurring under nature. Many other cases, however, might be + given to show the general rule, that under cessation of + selection complexity of structure degenerates more + rapidly--and also more thoroughly--than size of it. This, of + course, is what Mr. Galton and I should expect, seeing that + the more complex a structure the greater are the number of + points for deterioration to invade when the structure is no + longer "protected by selection." (On the other hand, of + course, this fact is opposed to the view that degeneration of + useless structures below the "birth-mean" of the first + generations, is exclusively due to the reversal of selection; + for economy of growth, deleterious effect of weight, and so + forth, ought to affect size of structure _much more_ than + complexity of it.) But I choose the above case, partly because + Professor Lloyd Morgan has himself alluded to "the eyes of + crustacea," and partly because Professor Ray Lankester has + maintained that the loss of these eyes in dark caves is due to + the reversal of selection, as distinguished from the cessation + of it. In view of the above parenthesis it will be seen that + the point is not of much importance in the present connexion; + but it appears to me that cessation of selection must here + have had at least the larger share in the process of atrophy. + For while the economy of nutrition ought to have removed the + relatively large _foot-stalks_ as rapidly as the _eyes_, I + cannot see that there is any advantage, other than the economy + of nutrition, to be gained by the rapid loss of hard-coated + _eyes_, even though they have ceased to be of use. + +To sum up. There is now no question in any quarter touching the fact +that panmixia, or the cessation of selection, is a true cause of +degeneration. The only question is as to the amount of degeneration +which it is able to effect when not assisted by the reversal of +selection, or any other cause of degeneration. Moreover, even with +regard to this question of amount, there is no doubt on any side that +panmixia alone causes degeneration _more rapidly_ where it has to do +with complexity of organization, than it does where it is concerned with +a mere reduction of mass. + +The question as to the amount of degeneration that is caused by the +cessation of selection alone is without any practical importance where +species in a state of nature are concerned, because here the cessation +of selection is probably always associated more or less with the +reversal of it; and it is as impossible as it is immaterial to determine +the relative shares which these two co-operating principles take in +bringing about the observed results. But where organisms in a state of +domestication are concerned, the importance of the question before us is +very great. For if the cessation of selection alone is capable of +reducing an organ through 10 or 12 per cent. of its original size, +nearly all the direct evidence on which Darwin relied in favour of +use-inheritance is destroyed. On the other hand, if reduction through 5 +per cent. be deemed a "very liberal estimate" of what this principle can +accomplish, the whole body of Darwin's direct evidence remains as he +left it. I have now given my reasons for rejecting this lower estimate +on the one band, and what seems to me the extravagant estimate of +Weismann on the other. But my own intermediate estimate is enough to +destroy the apparent proof of use-inheritance that was given by Darwin. +Therefore it remains for those who deny Lamarckian principles, either to +accept some such estimate, or else to acknowledge the incompatibility of +any lower one with the opinion that there is no evidence in favour of +these principles. + + + + +APPENDIX II. + +ON CHARACTERS AS ADAPTIVE AND SPECIFIC. + + +It is the object of this Appendix to state, more fully than in the text, +the opinions with regard to this subject which have been published by +the two highest authorities on the theory of natural selection--Darwin +and Professor Huxley. I will take first the opinion of Professor Huxley, +quoted _in extenso_, and then consider it somewhat more carefully than +seemed necessary in the text. + +As far as I am aware, the only occasion on which Professor Huxley has +alluded to the subject in question, is in his obituary notice of Darwin +in the _Proceedings of the Royal Society_, Vol. XLIV, No. 269, p. xviii. +The allusion is to my paper on _Physiological Selection_, in the +_Journal of the Linnæan Society_, Zool. Vol. XIX, pp. 337-411. But it +will be observed that the criticism has no reference to the theory which +it is the object of that paper to set forth. It refers only to my +definition of the theory of natural selection as primarily a theory of +the origin, or cumulative development, of adaptations. This criticism, +together with my answer thereto at the time, is conveyed in the +following words. + + "Every variety which is selected into a species is favoured and + preserved in consequence of being, in some one or more respects, + better adapted to its surroundings than its rivals. In other words, + every species which exists, exists in virtue of adaptation, and + whatever accounts for that adaptation accounts for the existence of + the species. To say that Darwin has put forward a theory of the + adaptation of species, but not of their origin, is therefore to + misunderstand the first principles of the theory. For, as has been + pointed out, it is a necessary consequence of the theory of + selection that every species must have some one or more structural + or functional peculiarities, in virtue of the advantage conferred + by which it has fought through the crowd of its competitors, and + achieved a certain duration. In this sense, it is true that every + species has been 'originated' by selection." + + Now, in the first place, I have nowhere said that "Darwin has put + forward a theory of the adaptation of species, but not of their + origin." I said, and continue to say, that he has put forward a + theory of _adaptations in general_, and that where such adaptations + appertain to species only (i.e. are peculiar to particular + species), the theory becomes "_also_ a theory of the origin of the + species which present them." The only possible misunderstanding, + therefore, which can here be alleged against me is, that I fail to + perceive it as a "necessary consequence of the theory of selection + that _every_ species _must_ have some one or more structural or + functional _peculiarities_" of an adaptive or utilitarian kind. + Now, if this is a misunderstanding, I must confess to not having + had it removed by Mr. Huxley's exposition. + + The whole criticism is tersely conveyed in the form of two sequent + propositions--namely, "Every species which exists, exists in virtue + of adaptation; and whatever accounts for that adaptation accounts + for the existence of the species." My answer is likewise two-fold. + First, I do not accept the premiss; and next, even if I did, I can + show that the resulting conclusion would not overturn my + definition. Let us consider these two points separately, beginning + with the latter, as the one which may be most briefly disposed of. + + I. Provisionally conceding that "every species which exists, exists + in virtue of adaptation," I maintain that my definition of the + theory of natural selection still holds good. For even on the basis + of this concession, or on the ground of this assumption, the theory + of natural selection is not shown to be "_primarily_" a theory of + the origin of species. It follows, indeed, from the assumption--is, + in fact, part and parcel of the assumption--that all species have + been originated by natural selection; but why? _Only because + natural selection has originated those particular adaptive features + in virtue of which (by the hypothesis) species exist as species._ + It is only in virtue of having created these features that natural + selection has created the species presenting them--just as it has + created genera, families, orders, &c., in virtue of _other_ + adaptive features extending through progressively wider areas of + taxonomic division. Everywhere and equally this principle has been + "primarily" engaged in the evolution of adaptations, and if one + result of its work has been that of enabling the systematist to + trace lines of genetic descent under his divisions of species, + genera, and the rest, such a result is but "secondary" or + "incidental." + + In short, it is "_primarily_" a theory of adaptations _wherever + these occur_, and only becomes "_also_" or "_incidentally_" a + theory of species in cases where adaptations happen to be + restricted in their occurrence to organic types of a certain order + of taxonomic division. + + II. Hitherto, for the sake of argument, I have conceded that, in + the words of my critic, "it is a necessary consequence of the + theory of selection that every species must have some one or more + structural or functional peculiarities" of an adaptive kind. But + now I will endeavour to show that this statement does not "follow + as a necessary consequence" from "the theory of selection." + + Most obviously "it follows" from the theory of selection that + "every variety which is selected into a species is favoured and + preserved in consequence of being, in some one or more respects, + better adapted to its surroundings than its rivals." This, in fact, + is no more than a re-statement of the theory itself. But it does + _not_ follow that "every species which exists, exists in virtue of + adaptation" _peculiar to that species_; i.e. that every species + which exists, exists _in virtue of having been "selected_." This + may or may not be true as a matter of fact: as a matter of logic, + the inference is not deducible from the selection theory. Every + variety which is "_selected into_" a species must, indeed, present + some such peculiar advantage; but this is by no means equivalent to + saying, "in other words," that every variety which _becomes_ a + species must do so. For the latter statement imports a completely + new assumption--namely, that every variety which _becomes_ a + species must do so because it has been "_selected into_" a species. + In short, what we are here told is, that if we believe the + selection principle to have given origin to some species, we must + further believe, "as a necessary consequence," that it has given + origin to all species. + +The above reply, which is here quoted _verbatim_ from _Nature_, Vol. 38, +p. 616-18, proceeded to show that it does not belong to "the first +principles of the theory of natural selection" to deny that no other +cause than natural selection can possibly be concerned in the origin of +species; and facts were given to prove that such unquestionably has been +the case as regards the origin of "local" or "permanent" _varieties_. +Yet such varieties are what Darwin correctly terms "incipient" species, +or species in process of taking _origin_. Therefore, if Professor +Huxley's criticism is to stand at all, we must accept it "as a necessary +consequence of the theory of selection," that every such _variety_ +"which exists, exists in virtue of adaptation"--a statement which is +_proved_ to be untrue by the particular cases forthwith cited. But as +this point has been dealt with much more fully in the text of the +present treatise, I shall sum up the main points in a few words. + +The criticism is all embodied in two propositions--namely, (_a_) that +the theory of natural selection carries with it, as a "necessary +consequence," the doctrine that survival of the fittest has been the +cause of the origin of _all_ species; and (_b_) that therefore it +amounts to one and the same thing whether we define the theory as a +theory of species or as a theory of adaptations. Now, as a mere matter +of logical statement, it appears to me that both these propositions are +unsound. As regards the first, if we hold with Darwin that other causes +have co-operated with natural selection in the origination of some (i. +e. many) species, it is clearly no part of the theory of natural +selection to assume that none of these causes can ever have acted +independently. In point of fact, as we have seen in the foregoing +chapters, such has probably and frequently been the case under the +influences of isolation, climate, food, sexual selection, and laws of +growth; but I may here adduce some further remarks with regard to yet +another possible cause. If the Lamarckian principles are valid at all, +no reason can be shown why in some cases they may not have been +competent _of themselves_ to induce morphological changes of type by +successive increments, until a transmutation of species is effected by +their action alone--as, indeed, Weismann believes to have been the case +with all the species of Protozoa[148]. That such actually has often been +the case also with numberless species of Metozoa, is the belief of the +neo-Lamarckians; and whether they are right or wrong in holding this +belief, it is equally certain that, _as a matter of logical reasoning_, +they are not compelled by it to profess any _disbelief_ in the agency of +natural selection. They may be mistaken as to the facts, as Darwin in a +lesser degree may have been similarly mistaken; but just as Darwin has +nowhere committed himself to the statement that _all_ species must +_necessarily_ have been originated by natural selection, so these +neo-Lamarckians are perfectly logical in holding that _some_ species may +have been wholly caused by the inheritance of acquired characters, as +_other_ species may have been wholly caused by the natural selection of +congenital characters. In short, unless we begin by assuming (with +Wallace and against Darwin) that there _can be no other cause_ of the +origin of species than that which is furnished by natural selection, we +have no basis for Professor Huxley's statement "that every species has +been originated by selection"; while, if we do set out with this +assumption, we end in a mere tautology. What ought to be done is to +prove the validity of this assumption; but, as Professor Huxley makes +no attempt to do this, his criticism amounts to mere begging of the +question. + + [148] Since the above was written Professor Weismann has transferred + this doctrine from the Protozoa to their ancestors. + +And now, as regards the second point (_b_), even if we grant the +assumption that natural selection is the only possible cause of the +origin of species--or, which is the same thing, that every species has +been originated by natural selection,--is it likewise the same thing +whether we define the theory of natural selection as a theory of species +or as a theory of adaptations? Professor Huxley's criticism endeavours +to show that it is; but a little consideration is enough to show that it +is not. What does follow from the assumption is, that, _so far as +specific characters are concerned_, it is one and the same thing to say +that the theory is a theory of species, and to say that it is a theory +of adaptations. But specific characters are not conterminous with +adaptive characters; for innumerable adaptive characters are not +distinctive of species, but of genera, families, orders, classes, and +sub-kingdoms. Therefore, if it is believed (as, of course, Professor +Huxley believes) that the theory in question explains the evolution of +all adaptive characters, obviously it is not one and the same thing to +define it indifferently as a theory of species or as a theory of +adaptations. + +Now, all this is not merely a matter of logic chopping. On the contrary, +the question whether we are to accept or to reject the deduction that +all species must necessarily have owed their origin to natural +selection, is a question of no small importance to the general theory of +evolution. And our answer to this question must be determined by that +which we give to the ulterior question--Is the theory of natural +selection to be defined as a theory of species, or as a theory of +adaptations? + + * * * * * + +We now pass on to our consideration of Darwin's opinion touching the +question, as stated by himself,--"The doctrine of utility, how far +true?" As I cannot ascertain that Darwin has anywhere expressed an +opinion as to whether natural selection has been necessarily concerned +in the origin of all _species_, the issue here is as to whether he held +this with regard to all _specific characters_. It will be remembered +that while opposing this doctrine as erroneous both in logic and in +fact, I have represented that it is not a doctrine which Darwin +sanctioned; but, on the contrary, that it is one which he expressly +failed to sanction, by recognizing the frequent inutility of specific +characters. Mr. Wallace, on the other hand, alleges that Darwin did +believe in the universal--as distinguished from the general--utility of +such characters. And he adds that he has "looked in vain in Mr. Darwin's +works" for any justification of my statements to the contrary[149]. +Therefore I will endeavour to show that Mr. Wallace's search has not +been a very careful one. + + [149] _Darwinism_, p. 131. He says:--"I have looked in vain in Mr. + Darwin's works for any such acknowledgement" (i.e. "that a + large proportion of specific distinctions must be conceded + useless to the species presenting them"). + +We must remember, however, that it was not until the appearance of my +paper on _Physiological Selection_, four years after Darwin's death, +that the question now in debate was raised. Consequently, he never had +occasion to deal expressly with this particular question--viz. whether +"the doctrine of utility" has any _peculiar_ reference to _specific_ +characters--as he surely would have done had he entertained the +important distinction between specific and all other characters which +Mr. Wallace now alleges that he did entertain. But, be this as it may, +we cannot expect to find in Darwin's writings any express allusion to a +question which had not been raised until 1886. The most we can expect to +find are scattered sentences which prove that the distinction in +question was never so much as present to his mind,--i. e. never occurred +to him as even a possible distinction. + +I will first take the passages which Mr. Wallace himself supplies from +among those which I had previously indicated. + + "But when, from the nature of the organism and of the conditions, + modifications have been induced which are unimportant for the + welfare of the _species_, they may be, and apparently often have + been, transmitted in nearly the same state to numerous, otherwise + modified, descendants[150]." + + [150] _Origin of Species_, p. 175. Italics mine. + +On this passage Mr. Wallace remarks that the last five words "clearly +show that such characters are usually not 'specific,' in the sense that +they are such as distinguish species from one another, but are found in +numerous allied species." But I cannot see that the passage shows +anything of the sort. What to my mind it does show is, (_a_) that Mr. +Darwin repudiated Mr. Wallace's doctrine touching the _necessary_ +utility of _all_ specific characters: (_b_) that he takes for granted +the contrary doctrine touching the inutility of _some_ specific +characters: (_c_) that without in this place alluding to the +proportional number of useless specific characters, he refers their +origin in some cases to "the nature of the organism" (i.e. "spontaneous +variability" due to internal causes), and in other cases to "the +conditions" (i.e. variability induced by external causes): (_d_) that +when established as a specific character by heredity, such a useless +character was held by him not to tend to become obsolete by the +influence of natural selection or any other cause; but, on the contrary, +to be "transmitted in nearly the same state to numerous, otherwise +modified, descendants"--or progeny of the species in genera, families, +&c.: (_e_) and, therefore, that useless characters which are now +distinctive of genera, families, &c., were held by him frequently, if +not usually, to point to uselessness of origin, when first they arose as +merely specific characters. Even the meaning which Mr. Wallace reads +into this passage must imply every one of these points; and therefore I +do not see that he gains much by apparently seeking to add this further +meaning--viz. that in Darwin's opinion there must have been some +unassignable reason preventing the occurrence of useless specific +characters in cases where species are _not_ destined to become the +parents of genera. + +Moreover, any such meaning is out of accordance with the context from +which the passage is taken. For, after a long consideration of the +question of utility, Darwin sums up,--"We thus see that with plants many +morphological changes may be attributed to the laws of growth and the +interaction of parts, _independently of natural selection_." And then he +adds,--"From the fact of the above characters being _unimportant for the +welfare of the species_, any slight variations which occurred in them +_would not have been augmented through natural selection_." Again, still +within the same passage, he says, while alluding to the causes other +than natural selection which lead to changes of specific +characters,--"If the _unknown cause_ were to act almost uniformly for a +length of time, we may infer that the result would be almost uniform; +and in this case _all_ the individuals of the _species_ would be +modified in the same manner." For my own part I do not understand how +Mr. Wallace can have overlooked these various references to _species_, +all of which occur on the very page from which he is quoting. The whole +argument is to show that "many morphological changes may be attributed +to the laws of growth and the inter-action of parts [_plus_ external +conditions of life], independently of natural selection"; that such +non-adaptive changes, when they occur as "specific characters," may, if +the species should afterwards give rise to genera, families, &c., become +distinctive of these higher divisions. But there is nothing here, or in +any other part of Darwin's writings, to countenance the inconsistent +notion which Mr. Wallace appears to entertain,--viz. that species which +present useless characters are more apt to give rise to genera, +families, &c., than are species which do not present such characters. + +The next passage which Mr. Wallace quotes, with his comments thereon, is +as follows. The italics are his. + + "'Thus a large yet undefined extension may safely be given to the + direct and indirect results of natural selection; but I now admit, + after reading the essay of Nägeli on plants, and the remarks by + various authors with respect to animals, more especially those + recently made by Professor Broca, that in the earlier editions of + my Origin of Species I perhaps attributed too much to the action of + natural selection, or the survival of the fittest. I have altered + the fifth edition of the Origin so as to confine my remarks to + adaptive changes of structure; _but I am convinced, from the light + gained during even the last few years, that very many structures + which now appear to be useless, will hereafter be proved to be + useful, and will therefore come within the range of natural + selection_. Nevertheless I did not formerly consider sufficiently + the existence of structures which, as far as we can at present + judge, are neither beneficial nor injurious; and this I believe to + be one of the greatest oversights as yet detected in my work.' + + Now it is to be remarked that neither in these passages nor in any + of the other less distinct expressions of opinion on this question, + does Darwin ever admit that "specific characters"--that is, the + particular characters which serve to distinguish one species from + another--are ever useless, much less that "a large proportion of + them" are so, as Mr. Romanes makes him "freely acknowledge." On the + other hand, in the passage which I have italicised he strongly + expresses his view that much of what we suppose to be useless is + due to our ignorance; and as I hold myself that, as regards many of + the supposed useless characters, this is the true explanation, it + may be well to give a brief sketch of the progress of knowledge in + transferring characters from the one category to the other[151]." + + [151] _Darwinism_, p. 132. + +It is needless to continue this quotation, because of course no one is +disputing that an enormous number of specific characters whose utility +is unknown are nevertheless useful, and therefore due to natural +selection. In other words, the question is not--Are there not many +useful specific characters whose utility is unknown? but--Does it follow +from the theory of natural selection that all specific characters must +necessarily be useful? Well, it appears to me that without going further +than the above passage, which Mr. Wallace has quoted, we can see clearly +enough what was Darwin's opinion upon the subject. He did not believe +that it followed _deductively_ from his theory that all specific +characters must necessarily be useful; and therefore he regarded it as a +question of _fact_--to be determined by induction as distinguished from +deduction--in what proportional number of cases they are so. Moreover he +gives it as his more matured opinion, that, "as far as we can at present +judge" (i.e. from the present state of observation upon the subject: if, +with Mr. Wallace, his judgement were _a priori_, why this +qualification?), he had not previously sufficiently considered the +existence of non-adaptive characters--and this he ended by believing was +one of the greatest oversights as yet detected in his work. To me it has +always seemed that this passage is one of the greatest exhibitions of +candour, combined with solidity of judgement, that is to be met with +even in the writings of Darwin. There is no talk about any deductive +"necessity"; but a perfect readiness to allow that causes other than +natural selection may have been at work in evoking non-adaptive +characters, so that the fifth edition of the _Origin of Species_ was +altered in order to confine the theory of natural selection to "adaptive +changes"--i.e. to constitute it, as I have said in other words, "a +theory of the origin, or cumulative development, of _adaptations_." + +If to this it be said that in the above passage there is no special +mention of _species_, the quibble would admit of a three-fold reply. In +the first place, the quibble in question had never been raised. As +already stated, it is only since the appearance of my own paper on +_Physiological Selection_ that anybody ever thought of drawing a +distinction between species and genera, such that while all specific +characters must be held necessarily useful, no such necessity extends to +generic characters. In the second place, that Darwin must have had +specific characters (as well as generic) in his mind when writing the +above passage, is rendered unquestionable by the fact that many of the +instances of inutility adduced by Nägeli and Broca have reference to +specific characters. Lastly, as shown in the passages previously quoted +from the sixth edition of the _Origin of Species_, Darwin attributed the +origin of useless generic characters to useless specific characters; so +that Mr. Wallace really gains nothing by his remark that specific +characters are not specially mentioned in the present passage. + +Once more:-- + + "Darwin's latest expression of opinion on this question is + interesting, since it shows he was inclined to return to his + earlier view of the general, or universal, utility of specific + characters[152]." + + [152] _Darwinism_, p. 142. + +This "latest expression of opinion," as I shall immediately prove, shows +nothing of the kind--being, in fact, a mere re-statement of the opinion +everywhere and at all times expressed by Darwin, touching the caution +that must be observed in deciding, _with respect to individual cases_, +whether an apparently useless specific character is to be regarded as +really useless. Moreover, at no time and in no place did Darwin +entertain any "view of the general, or universal, utility of specific +characters." But the point now is, that if (as was the case) Darwin +"inclined" to depart more and more from his earlier view of the highly +_general_ utility of specific characters; and if (as was not the case) +he ended by showing an inclination "_to return_" to this earlier view; +what becomes of the whole of Mr. Wallace's contention against which +this Appendix is directed, namely, _that Darwin never entertained any +other view than that of the "general, or universal, utility of specific +characters_"? + +The "latest expression of opinion" which Mr. Wallace quotes, occurs in a +letter written to Professor Semper in 1878. It is as follows:-- + + "As our knowledge advances, very slight differences, considered by + systematists as of no importance in structure, are continually + found to be functionally important; and I have been especially + struck with this fact in the case of plants, to which my + observations have of late years been confined. Therefore it seems + to me rather rash to consider the slight differences between + representative species, for instance those inhabiting the different + islands of the same archipelago, as of no functional importance, + and as not in any way due to natural selection[153]." + + [153] _Life and Letters_, vol. iii. p. 161. + +Now, with regard to this passage it is to be observed, as already +remarked, that it refers to the formation of final judgements touching +_particular cases_: there is nothing to show that the writer is +contemplating _general principles_, or advocating on deductive grounds +the dogma that specific characters must be necessarily and universally +adaptive characters. Therefore, what he here says is neither more nor +less than I have said. For I have always held that it would be "rather +rash" to conclude that any given cases of apparent inutility are +certainly cases of real inutility, _merely on the ground that utility is +not perceived_. But this is clearly quite a distinct matter from +resisting the _a priori_ generalization that all cases of apparent +inutility must certainly be cases of real utility. And, I maintain, in +every part of his writings, without any exception, where Darwin alludes +to this matter of general principle, it is in terms which directly +contradict the deduction in question. As the whole of this Appendix has +been directed to proving that such is the case, it will now, I think, be +sufficient to supply but one further quotation, in order to show that +the above "latest expression of opinion," far from indicating that in +his later years Darwin "inclined" to Mr. Wallace's views upon this +matter, is quite compatible with a distinct "expression of opinion" to +the contrary, in a letter written less than six years before his death. + + "In my opinion _the greatest error which I have committed_, has + been not allowing sufficient weight to the direct action of the + environment, i.e. food, climate, &c., _independently of natural + selection_. Modifications thus caused, _which are neither of + advantage nor disadvantage to the modified organisms_, would be + especially favoured, as I can now see chiefly through your + observations, _by isolation in a small area, where only a few + individuals lived under nearly uniform conditions_[154]." + + [154] _Life and Letters_, vol. iii. p. 158. + +I will now proceed to quote further passages from Darwin's works, which +appear to have escaped the notice of Mr. Wallace, inasmuch as they admit +of no doubt regarding the allusions being to _specific_ characters. + + "_We may easily err in attributing importance to characters, and in + believing that they have been developed through natural selection._ + We must by no means overlook the effects of the definite action of + changed conditions of life,--of so-called spontaneous variations, + which seem to depend in a quite subordinate degree on the nature of + the conditions,--of the tendency to reversion to long-lost + characters,--of the complex laws of growth, such as of + correlation[155], compensation, of pressure of one part on another, + &c., and finally of sexual selection, by which characters of use to + one sex are often gained and then transmitted more or less + perfectly to the other sex, though of no use to this sex. But + structures thus indirectly gained, _although at first of no + advantage to a species_, may subsequently have been taken advantage + of by its modified descendants, under new conditions of life and + newly acquired habits[156]." + + [155] It must be observed that Darwin uses this word, not as Mr. + Wallace always uses it (viz. as if correlation can only be + with regard to adaptive characters), but in the wider sense + that any change in one part of an organism--whether or not it + happens to be an adaptive change--is apt to induce changes in + other parts. + + [156] _Origin of Species_, pp. 157-8. + +It appeared--and still appears--to me, that where so many causes are +expressly assigned as producing useless _specific_ characters, and that +some of them (such as climatic influences and independent variability) +must be highly general in their action, I was justified in representing +it as Darwin's opinion that "a large proportional number of specific +characters" are useless to the _species_ presenting them, although +afterwards they may sometimes become of use to genera, families, &c. +Moreover, this passage goes on to point out that specific characters +which at first sight appear to be obviously useful, are sometimes found +by fuller knowledge to be really useless--a consideration which is the +exact inverse of the argument from ignorance as used by Mr. Wallace, and +serves still further to show that in Darwin's opinion utility is by no +means an invariable, still less a "necessary," mark of specific +character. The following are some of the instances which he gives. + + "The sutures in the skulls of young mammals have been advanced as a + beautiful adaptation for aiding parturition, and no doubt they may + facilitate, or be indispensable for this act; but as sutures occur + in the skulls of young birds and reptiles, which have only to + escape from a broken egg, we may infer that this structure has + _arisen from the laws of growth_, and has been taken advantage of + in the parturition of the higher animals[157]." + + "The naked skin on the head of a vulture is generally considered as + a direct adaptation for wallowing in putridity; and so it may be, + _or it may possibly be due to the direct action of the putrid + matter_; but we should be very cautious in drawing any such + inference [i.e. as to utility] when we see the skin on the head of + the clean-feeding male Turkey is likewise naked[158]." + + [157] _Ibid._ + + [158] _Origin of Species_, pp. 157-8. + +Similarly, in the _Descent of Man_ it is said:-- + + "Variations of the same _general_ nature have _often been taken + advantage of_ and accumulated through sexual selection in relation + to the propagation of the species, and through natural selection in + relation to the general purposes of life. Hence, _secondary sexual + characters, when equally transmitted to both sexes, can be + distinguished from ordinary specific characters, only by the light + of analogy_. The modifications acquired through sexual selection + are often so strongly pronounced that the two sexes have frequently + been ranked as distinct species, or even as distinct genera[159]." + + [159] _Descent of Man_, p. 615. + +As Mr. Wallace does not recognize sexual selection, he incurs the burden +of proving utility (in the life-preserving sense) in all these +"frequently" occurring cases where there are such "strongly pronounced +modifications," and we have already seen in the text his manner of +dealing with this burden. But the point here is, that whether or not we +accept the theory of sexual selection, we must accept it as Darwin's +opinion--first, that in their beginnings, as _specific_ characters, +these sexual modifications were often of a merely "_general nature_" (or +without reference to utility even in the life-embellishing sense), and +only _afterwards_ "have often been taken advantage of and accumulated +through _sexual_ selection": and, secondly, that "we know they have been +acquired in some instances _at the cost not only of inconvenience, but +of exposure to actual dangers_[160]." + + [160] _Ibid._ + +We may now pass on to some further, and even stronger, expressions of +opinion with regard to the frequent inutility of _specific_ characters. + + "I have made these remarks only to show that, if we are unable to + account for the characteristic differences of our several domestic + breeds, which nevertheless are generally admitted to have arisen + through ordinary generation from one or a few parent stocks, we + ought not to lay too much stress on our ignorance of the precise + cause [i.e. whether natural selection or some other cause] of the + slight analogous differences between true _species_.... I fully + admit that _many_ structures are now of no use to their possessors, + and may never have been of any use to their progenitors; but this + does not prove that they were formed solely for beauty or variety. + No doubt the definite action of changed conditions, and the various + causes of modification, lately specified, have all produced an + effect, _probably a great effect, independently of any advantage + thus gained_.... It is scarcely possible to decide how much + allowance ought to be made for such causes of change, as the + definite action of external conditions, so-called spontaneous + variations, and the complex laws of growth; but, _with these + important exceptions_, we may conclude that the structure of every + living creature either now is, or formerly was, of some direct or + indirect use to its possessor[161]." + + [161] _Descent of Man_, pp. 159-60. + +Here again, if we remember how "important" these "exceptions" are, I +cannot understand any one doubting Darwin's opinion to have been that a +large proportional number of specific characters are useless. For that +it is "species" which he here has mainly in his mind is evident from +what he says when again alluding to the subject in his "Summary of the +Chapter"--namely, "In _many_ other cases [i.e. in cases where natural +selection has not been concerned] modifications are probably the direct +result of the laws of variation or of growth, independently of any good +having been thus gained." Now, not only do these "laws" apply as much to +species as they do to genera; "but," the passage goes on to say, "even +such structures have often, we may feel assured, been subsequently +taken advantage of, and still further modified, for the good of +_species_ under new conditions of life." Obviously, therefore, the +inutility in such cases is taken to have been prior to any utility +subsequently acquired; and genera are not historically prior to the +species in which they originate. + +Here is another quotation:-- + + "Thus, as I am inclined to believe, morphological differences, + which we consider as important--such as the arrangement of the + leaves, the divisions of the flower or of the ovarium, the position + of the ovules, &c.--_first_ appeared in _many_ cases as + _fluctuating variations_, which sooner or later became constant + through the nature of the organism and of the surrounding + conditions, as well as through the intercrossing of distinct + individuals, _but not through natural selection_; for as these + morphological characters do not affect the welfare of the + _species_, any slight deviations in them could not have been + governed or accumulated through this latter agency. It is a strange + result which we thus arrive at, namely, that characters of slight + vital importance to the _species_, are the most important to the + systematist; but, as we shall hereafter see when we treat of the + genetic principle of classification, this is by no means so + paradoxical as it may at first appear[162]." + + [162] _Descent of Man_, p. 176. + +Clearly the view here expressed is that characters which are now +distinctive of higher taxonomic divisions "first appeared" in the parent +species of such divisions; for not only would it be unreasonable to +attribute the rise and preservation of useless characters to +"fluctuating variations" affecting a number of species or genera +similarly and simultaneously; but it would be impossible that, if such +were the case, they could be rendered "constant through the nature of +the organism and of the surrounding conditions, as well as through the +intercrossing of distinct individuals[163]." + + [163] The passage to which these remarks apply is likewise quoted, + in the same connexion as above, in my paper on _Physiological + Selection_. In criticising that paper in _Nature_ (vol. xxxix. + p. 127), Mr. Thiselton Dyer says of my interpretation of this + passage, "the obvious drift of this does not relate to + specific differences, but to those which are characteristic of + family." But in making this remark Mr. Dyer could not have + read the passage with sufficient care to note the points which + I have now explained. + +Here is another passage to the same general effect. In alluding to the +objection from inutility as advanced by Bronn, Broca, and Nägeli, Mr. +Darwin says:--"There is much force in the above objection"; and, after +again pointing out the important possibility in any particular cases of +hidden or former use, and the action of the laws of growth, he goes on +to say,--"In the third place, we have to allow for the direct and +definite action of changed conditions of life, and for so-called +spontaneous variations, in which the nature of the conditions plays +quite a subordinate part[164]." Elsewhere he says,--"It appears that I +formerly underrated the frequency and value of these latter forms of +variation as leading to permanent modifications of structure +_independently of natural selection_[165]." The "forms of variation" to +which he here alludes are "variations which seem to us in our ignorance +to arise spontaneously"; and it is evident that such variations cannot +well "arise" in two or more species of a genus similarly and +simultaneously, so as independently to lead "to permanent modifications +of structure" in two or more parallel lines. It is further evident that +by "spontaneous variations" Darwin alludes to extreme cases of +spontaneous departure from the general average of specific characters; +and therefore that lesser or more ordinary departures must be of still +greater "frequency." + + [164] _Origin of Species_, p. 171. + + [165] _Ibid._ p. 421. + +Again, speaking of the principles of classification, Darwin writes:-- + + "We care not how trifling a character may be--let it be the mere + inflection of the angle of the jaw, the manner in which an + insect's wing is folded, whether the skin be covered by hair or + feathers--if it prevail throughout many and different species, + especially those having very different habits of life, it assumes + high value [i.e. for purposes of classification]; for we can + account for its presence in so many forms with such _different + habits_, only by inheritance from a common parent. We may err in + this respect in regard to single points of structure, but when + several characters, let them be ever so trifling, concur throughout + a large group of beings _having different habits_, we may feel + almost sure, on the theory of descent, that these characters have + been inherited from a common ancestor; and we know that such + aggregated characters have especial value in classification[166]." + + [166] _Origin of Species_, pp. 372-373. + +Now it is evident that this argument for the general theory of evolution +would be destroyed, if Wallace's assumption of utility of specific +characters as universal were to be entertained. And the fact of +apparently "trifling" characters occurring throughout a large group of +beings "having different habits" is proof that they are really trifling, +or without utilitarian significance. + +It is needless to multiply these quotations, for it appears to me that +the above are amply sufficient to establish the only point with which we +are here concerned, namely, that Darwin's opinion on the subject of +utility in relation to specific characters was substantially identical +with my own. And this is established, not merely by the literal meaning +of the sundry passages here gathered together from different parts of +his writings; but likewise, and perhaps still more, from the tone of +thought which pervades these writings as a whole. It requires no words +of mine to show that the literal meaning of the above quotations is +entirely opposed to Mr. Wallace's view touching the _necessary_ utility +of _all_ specific characters; but upon the other point--or the general +tone of Mr. Darwin's thought regarding such topics--it may be well to +add two remarks. + +In the first place, it must be evident that so soon as we cease to be +bound by any _a priori_ deduction as to natural selection being "the +exclusive means of modifications," it ceases to be a matter of much +concern to the theory of natural selection in what proportion other +means of modification have been at work--especially when non-adaptive +modifications are concerned, and where these have reference to merely +"specific characters," or modifications of the most incipient kind, +least generally diffused among organic types, and representing the +incidence of causes of less importance than any others in the process of +organic evolution considered as a whole. Consequently, in the second +place, we find that Darwin nowhere displays any solicitude touching the +proportional number of specific characters that may eventually prove to +be due to causes other than natural selection. He takes a much wider and +deeper view of organic evolution, and, having entirely emancipated +himself from the former conception of species as the organic units, sees +virtually no significance in specific characters, except in so far as +they are also adaptive characters. + +Such, at all events, appears to me the obvious interpretation of his +writings when these are carefully read with a view to ascertaining his +ideas upon "Utilitarian doctrine: how far true." And I make these +remarks because it has been laid to my charge, that in quoting such +passages as the above I have been putting "a strained interpretation" +upon Darwin's utterances: "such admissions," it is said, "Mr. Romanes +appears to me to treat as if wrung from a hostile witness[167]." But, +from what has gone before, it ought to be apparent that I take precisely +the opposite view to that here imputed. Far from deeming these and +similar passages as "admissions wrung from a hostile witness," and far +from seeking to put any "strained interpretation" upon them, I believe +that they are but the plain and unequivocal expressions of an opinion +which I have always understood that Darwin held. And if any one has been +led to think otherwise, I throw back this charge of "strained +interpretation," by challenging such a person to adduce a single +quotation from any part of Darwin's works, which can possibly be held to +indicate that he regarded passages like those above quoted as in any way +out of conformity with his theory of natural selection--or as put +forward merely to "admit the possibility of explanations, to which +really, however, he did not attach much importance." To the best of my +judgement it is only some bias in favour of Mr. Wallace's views that can +lead a naturalist to view in this way the clear and consistent +expression of Darwin's. + + [167] Mr. Thiselton Dyer in _Nature_, _loc. cit._ + +That Mr. Wallace himself should be biassed in this matter might, +perhaps, be expected. After rendering the following very unequivocal +passage from the _Origin of Species_ (p. 72)--"There can be little doubt +that the tendency to vary in the same manner has often been so strong, +_that all individuals of the same species have been similarly modified +without the aid of any form of selection_"--Mr. Wallace says, "But no +proof whatever is offered of this statement, and it is so entirely +opposed to all we know of the facts of variation as given by Darwin +himself, that the important word 'all' is probably an oversight." But, +if Mr. Wallace had read the very next sentence he would have seen that +here the important word "all" could not _possibly_ have been "an +oversight." For the passage continues,--"Or only a third, fifth, or +tenth part of the individuals may have been thus affected, of which fact +several instances could be given. Thus Graba estimates that about +one-fifth of the guillemots in the Faroe Islands consist of a variety so +well marked, that it was formerly ranked as a distinct species under the +name of Uria lacrymans." And even if this passage had not been thus +specially concerned with the question of the _proportion_ in which +"_individuals of the same species have been similarly modified without +the aid of any form of selection_" the oversight with respect to "the +important word 'all'" would still have remained an oversight of a +recurrent character, as the following additional quotations from other +parts of Darwin's writings may perhaps render apparent. + + "There must be some efficient cause for each slight individual + difference, as well as for more strongly marked variations which + occasionally arise; and if the unknown cause were to act + persistently, it is almost certain that _all_ the individuals of + the _species_ would be similarly modified[168]." + + "The acquisition of a useless part can hardly be said to raise an + organism in the natural scale.... We are so ignorant of the + exciting cause of the above specified modifications; but if the + unknown cause were to act almost uniformly for a length of time, we + may infer that the result would be almost uniform; and in this case + _all_ the individuals of the _species_ would be modified in the + same manner[169]." + + [168] _Origin of Species_, p. 171. + + [169] _Ibid._ p. 175. + +Moreover, when dealing even with such comparatively slight changes as +occur between our domesticated varieties--and which, _a fortiori_, are +less likely to become "stable" through the uniform operation of causes +other than selection, seeing that they are not only smaller in amount +than occurs among natural species, but also have had but a comparatively +short time in which to accumulate--Darwin is emphatic in his assertion +of the same principles. For instance, in the twenty-third chapter of the +_Variation of Plants and Animals under Domestication_, he repeatedly +uses the term "definite action of external conditions," and begins the +chapter by explaining his use of the term thus:-- + + "By the term definite action, as used in this chapter, I mean an + action of such a nature that, when many individuals of the same + variety are exposed during several generations to any change in + their physical conditions of life, _all_, or _nearly all_, the + individuals are modified in the same manner. A new _sub-variety_ + would thus be produced _without the aid of selection_[170]." + + [170] _Variation_, &c., vol. ii. p. 260. + +As an example of the special instances that he gives, I may quote the +following from the same work:-- + + "Each of the endless variations which we see in the plumage of our + fowls must have had some efficient cause; and if the same cause + were to act uniformly during a long series of generations on many + individuals, _all_ probably would be modified in the same manner." + +And, as instances of his more general statements in Chapter XXIII, these +may suffice:-- + + "The direct action of the conditions of life, whether leading to + definite or indefinite results, _is a totally distinct + consideration from the effects of natural selection_.... The direct + and definite action of changed conditions, in contradistinction to + the accumulation of indefinite variations, _seems to me so + important_ that I will give a large additional body of + miscellaneous facts[171]." + + [171] _Ibid._ vol. ii. p. 261. + +Then, after giving these facts, and showing how in the case of species +in a state of nature it is often impossible to decide how much we are to +attribute to natural selection and how much to the definite action of +changed conditions, he begins his general summary of the chapter thus:-- + + "There can be no doubt, from the facts given in the early part of + this chapter, that extremely slight changes in the conditions of + life sometimes act in a definite manner on our already variable + domesticated productions [productions, therefore, with regard to + which uniformity and 'stability' of modification are least likely + to arise]; and, as the action Of changed conditions in causing + general or indefinite variability is accumulative, so it may be + with their definite action. Hence it is possible that _great_ and + _definite_ modifications of structure may result from altered + conditions acting during a long series of generations. In some few + instances a marked effect has been produced quickly on _all_, or + _nearly all_, the individuals which have been exposed to some + considerable change of climate, food, or other circumstance[172]." + + [172] _Variation_, &c., vol. ii. p. 280. + +Once more, in order to show that he retained these views to the end of +his life, I may quote a passage from the second edition of the _Descent +of Man_, which is the latest expression of his opinion upon these +points:-- + + "Each of the endless diversities in plumage, which we see in our + domesticated birds, is, of course, the result of some definite + cause; and under natural and more uniform conditions, some one + tint, _assuming that it was in no way injurious, would almost + certainly sooner or later prevail_. The free-intercrossing of the + many individuals belonging to the same species would ultimately + tend to make any change of colour thus induced _uniform in + character_.... Can we believe that the very slight differences in + tints and markings between, for instance, the female black-grouse + and red-grouse serve as a protection? Are partridges as they are + now coloured, better protected than if they had resembled quails? + Do the slight differences between the females of the common + pheasant, the Japan and golden pheasants, serve as a protection, or + might not their plumage have been interchanged with impunity? From + what Mr. Wallace has observed of the habits of certain gallinaceous + birds in the East, he thinks that such slight differences are + beneficial. For myself, I will only say, I am not convinced[173]." + + [173] _Descent of Man_, pp. 473-4. + +Yet "convinced" he certainly must have been on merely _a priori_ +grounds, had he countenanced Mr. Wallace's reasoning from the general +theory of natural selection; and the fact that he here fails to be +convinced even by "what Mr. Wallace has observed of the habits of +certain gallinaceous birds," appears to indicate that he had considered +the question of utility with special reference to Mr. Wallace's opinion. +That opinion was then, as now, the avowed result of a theoretical +prepossession; and this prepossession, as the above quotations +sufficiently show, was expressly repudiated by Darwin. + +Lastly, this is not the only occasion on which Darwin expressly +repudiates Mr. Wallace's opinion on the point in question. For it is +notorious that these co-authors of the theory of natural selection have +expressed divergent opinions concerning the origin by natural selection +of the most general of all specific characters--cross-sterility. +Although allowing that cross-sterility between allied species may be of +adaptive value in "keeping incipient species from blending," Darwin +persistently refused to be influenced by Wallace's belief that it is due +to natural selection; i.e. the belief on which alone can be founded the +"necessary deduction" with which we have been throughout concerned. + + + + +NOTE A TO PAGE 57. + + +I think it is desirable here to adduce one or two concrete illustrations +of these abstract principles, in order to show how, as a matter of fact, +the structure of Weismann's theory is such as to preclude the +possibility of its assumptions being disproved--and this even supposing +that the theory is false. + +At first sight nothing could seem more conclusive on the side of +Darwinian or Lamarckian principles than are the facts of hereditary +disease, in cases where the disease has unquestionably been acquired by +the parents. Take, for example, the case of gout. Here there is no +suspicion of any microbe being concerned, nor is there any question +about the fact of the disease being one which is frequently acquired by +certain habits of life. Now, suppose the case of a man who in middle age +acquires the gout by these habits of life--such as insufficient +exercise, over-sufficient food, and free indulgence in wine. His son +inherits the gouty diathesis, and even though the boy may have the fear +of gout before his eyes, and consequently avoid over-eating and +alcoholic drinking, &c., the disease may overtake him also. Well, the +natural explanation of all this is, that the sins of the fathers descend +upon the children; that gout acquired may become in the next generation +gout transmitted. But, on the other hand, the school of Weismann will +maintain that the reason why the parent contracted the gout was because +he had a congenital, or "blastogenetic," tendency towards that +disease--a tendency which may, indeed, have been intensified by his +habits of life, but which, in so far as thus intensified, was not +transmitted to his offspring. All that was so transmitted was the +congenital tendency; and all that is proved by such cases as those above +supposed, where the offspring of gouty parents become gouty +notwithstanding their abstemious habits, is that in such offspring the +congenital tendency is even more pronounced than it was in their +parents, and therefore did not require so much inducement in the way of +unguarded living to bring it out. Now, here again, without waiting to +consider the relative probabilities of these two opposing explanations, +it is enough for the purposes of the illustration to remark that it is +obviously impossible to disprove either by means of the other, or by any +class of facts to which they may severally appeal. + +I will give only one further example to show the elusiveness of +Weismann's theory, and the consequent impossibility of finding any cases +in nature which will satisfy the conditions of proof which the theory +imposes. In one of his papers Weismann says that if there be any truth +in the Lamarckian doctrine of the transmission of acquired characters, +it ought to follow that the human infant should speak by instinct. For, +ever since man became human he has presumably been a talking animal: at +any rate it is certain that he has been so for an innumerable number of +generations. Therefore, by this time the faculty of language ought to +have been so deeply impressed upon the psychology of the species, that +there ought to be no need to teach the young child its use of language; +and the fact that there is such need is taken by Weismann to constitute +good evidence in proof of the non-transmissibility of individually +acquired characters. Or, to quote his own words, "it has never yet been +found that a child could read of itself, although its parents had +throughout their whole lives practised this art. Not even are our +children able to talk of their own accord; yet not only have their +parents, but, more than that, an infinitely long line of ancestors have +never ceased to drill their brains and to perfect their organs of +speech.... From this alone we may be disposed to doubt whether acquired +capabilities in the true sense can ever be transmitted." Well, in answer +to this particular case, we have first of all to remark that the +construction of even the simplest language is, psychologically +considered, a matter of such enormous complexity, that there is no real +analogy between it and the phenomena of instinct: therefore the fact +that Lamarckian principles cannot be applied to the case of language is +no evidence that they do not hold good as regards instinct. Secondly, +not only the construction, but still more the use of language is quite +out of analogy with all the phenomena of instinct; for, in order to use, +or speak, a language, the mind must already be that of a thinking agent; +and therefore to expect that language should be instinctive is +tantamount to expecting that the thought of which it is the vehicle +should be instinctive--i.e. that human parents should transmit the whole +organization of their own intellectual experiences to their unborn +children. Thirdly, even neglecting these considerations, we have to +remember that language has been itself the product of an immensely long +course of evolution; so that even if it were reasonable to expect that a +child should speak by instinct without instruction, it would be +necessary further to expect that the child should begin by speaking in +some score or two of unknown tongues before it arrived at the one which +alone its parents could understand. Probably these considerations are +enough to show how absurd is the suggestion that Darwinians ought to +expect children to speak by instinct. But, now, although it is for these +reasons preposterous under any theory of evolution to expect that +children should be able to use a fully developed language without +instruction, it is by no means so preposterous to expect that, if all +languages present any one simple set of features in common, these +features might by this time have grown to be instinctive; for these +simple features, being common to all languages, must have been +constantly and forcibly impressed upon the structure of human psychology +throughout an innumerable number of sequent generations. Now, there is +only one set of features common to all languages; and this comprises the +combinations of vowel and consonantal sounds, which go to constitute +what we know as articulate syllables. And, is it not the case that these +particular features, thus common to all languages, as a matter of fact +actually _are_ instinctive? Long before a young child is able to +understand the meanings of any words, it begins to babble articulate +syllables; and I do not know that a more striking fact can be adduced at +the present stage of the Weismann controversy than is this fact which he +has thus himself unconsciously suggested, namely, that the young of the +only talking animal should be alone in presenting--and in unmistakably +presenting--the instinct of articulation. Well, such being the state of +matters as regards this particular case, in the course of a debate which +was held at the Newcastle meeting of the British Association upon the +heredity question, I presented this case as I present it now. And +subsequently I was met, as I expected to be met, by its being said that +after all the faculty of making articulate sounds might have been of +congenital origin. Seeing of how much importance this faculty must +always have been to the human species, it may very well have been a +faculty which early fell under the sway of natural selection, and so it +may have become congenital. Now, be it remembered, I am only adducing +this case in illustration of the elusiveness of Weismann's theory. First +of all he selects the faculty of articulate speech to argue that it is a +faculty which ought to be instinctive if acquired characters ever do +become instinctive; and so good does he deem it as a test case between +the two theories, that he says _from it alone_ we should be prepared to +accept the doctrine that acquired characters can never become +congenital. Then, when it is shown that the only element in articulate +speech which possibly could have become congenital, actually has become +congenital, the answer we receive is a direct contradiction of the +previous argument: the faculty originally selected as representative of +an acquired character is now taken as representative of a congenital +one. By thus playing fast and loose with whatever facts the followers of +Darwin may adduce, the followers of Weismann bring their own position +simply to this:--All characters which can be shown to be inherited we +assume to be congenital, or as we term it, "blastogenetic," while all +characters which can be shown not to be inherited, we assume to be +acquired, or as we term it, "somatogenetic"--and this merely on the +ground that they have been shown to be inherited or not inherited as the +case may be. Now, there need be no objection to such assumptions, +provided they are recognized as assumptions; but so long as the very +question in debate has reference to their validity as assumptions, it is +closely illogical to adduce them as arguments. And this is the only +point with which we are at present concerned. + + + + +NOTE B TO PAGE 89. + + +In answer to this illustration as previously adduced by me, Mr. Poulton +has objected that the benefit arising from the peculiar mode of stinging +in question is a benefit conferred, not on the insect which stings, but +upon its progeny. The point of the illustration however has no reference +to the maternal instinct (which here, as elsewhere, I doubt not is due +to natural selection); it has reference only to the particular instinct +of selective stinging, which here ministers to the purposes of the other +and more general instinct of rearing progeny. Given then the maternal +instinct of stinging prey for the use of progeny, the question is--What +first determined the ancestors of the Sphex to sting their prey only in +nine particular points? Darwin's answer to this question is as +follows:-- + + "I have been thinking about Pompilius and its allies. Please take + the trouble to read on perforation of the corolla by Bees, p. 425 + of my 'Cross-fertilization,' to end of chapter. Bees show so much + intelligence in their acts, that it seems not improbable to me that + the progenitors of Pompilius originally stung caterpillars and + spiders, &c., in any part of their bodies, and then observed by + their intelligence that if they stung them in one particular place, + as between certain segments on the lower side, their prey was at + once paralyzed. It does, not seem to me at all incredible that this + action should then become instinctive, i.e. memory transmitted from + one generation to another. It does not seem necessary to suppose + that when Pompilius stung its prey in the ganglion it intended or + knew that their prey would keep long alive. The development of the + larvae may have been subsequently modified in relation to their + half-dead, instead of wholly dead prey; supposing that the prey was + at first quite killed, which would have required much stinging. + Turn this over in your mind," &c. + +Weismann, on the other hand, can only suppose that this intensely +specialized instinct had its origin in fortuitous variations in the +psychology of the species. But, neglecting the consideration that, in +order to become fixed as an instinct by natural selection, the +particular variation required must have occurred in many different +individuals, not only in the first, but also in the sequent generations, +the chances against its occurring only once, or in but one single +individual case, are many thousands if not millions to one. + + + + +INDEX + + +A. + +Acceleration and retardation, 16. + +Acquired characters, heredity of, 39, 103, 133. + +Adaptation, 7, 13, 55, 62, 67, 71, 159, 165; + of species and of specific characters, 166. + +ALLEN, Mr., referred to, 209. + +_All-sufficiency of Natural Selection_, referred to, 65, 95. + +_Alone with the Hairy Ainu_, referred to, 26. + +American and European trees compared, 201. + +_American Journal of Science_, referred to, 273. + +_American Naturalist_, referred to, 35, 58. + +Ammonites, species of, 254. + +_Animal Intelligence_, referred to, 93. + +_Animal Life_, referred to, 101. + +_Animal Life and Intelligence_, referred to, 33, 36. + +_Apparent Paradox in Mental Evolution_, referred to, 90. + +Appendages of Normandy and Irish pigs, 188. + +Articulation and inheritance, 335. + +Artistic faculties of man, 27. + + +B. + +BABINGTON, Prof., referred to, 252. + +BACHMAN, Dr., referred to, 186. + +BAILEY, Prof., referred to, 127. + +BAKER, Mr., referred to, 252. + +Balancing of brainless frog, 78. + +BALL, Mr. Platt, referred to, 3, 95; quoted, 50. + +BATESON, Mr. W., referred to, 36. + +BEDDARD, Mr. F., referred to, 174. + +BENTHAM, Mr., referred to, 252. + +Birds, diagnostic characters of, 176; + of Australia, effect of climate on, 210; + influence of food on, 218. + +Blastogenetic, 123, 242, 245, 250. + +Blending of adaptations, 67. + +_Brain_, referred to, 80. + +BROCA, Prof., referred to, 64, 67, 174, 318. + +BRONN, Prof., referred to, 174. + +BROOKS, Prof., referred to, 14. + +BROWN-SÉQUARD, referred to, 104, 122, 142; quoted, 104. + +BUCKLEY, Mr., referred to, 147. + +BUCKMAN, Prof. James, referred to, 125. + +BUCKMAN, Prof. S.S., referred to, 24. + +BUTLER, Mr. A. G., referred to, 254. + +BUTLER, Mr. Samuel, referred to, 87. + +Butterfly, seasonal changes of, 210; + influence of food on, 217. + + +C. + +Carnivora, instincts of, 89. + +CARRIÈRE, M. L. A., referred to, 123. + +Cave animals, colour-changes in, 211. + +_Cave Fauna of North America_, quoted, 211. + +Cessation of Selection, 99, 199, 212, 292. + +Characters, adaptive and specific, 159, 307; + specific, due to Natural Selection, 171. + +_Charadriidae, Geographical Distribution of the Family_, quoted, 173. + +Chimpanzee, counting of, 31. + +Climate, influence of, on plants, 200; + on animals, 209. + +Co-adaptation, 64. + +COCKERELL, Prof., referred to, 218. + +Colour, 269. + +Colour-changes in butterflies, 210. + in cave animals, 211. + +_Colours of Animals_, referred to, 36. + +Congenital, as opposed to acquired characters, 134. + +Constancy of characters not necessarily due to Natural Selection, 186. + +_Contemporary Review_, referred to, 60, 65, 95 + +Continuity of germ-plasm, 44, 61, 133; + absolute and relative, 134, 155. + +_Contributions to the Theory of Natural Selection_, referred to, 2; +quoted, 180. + +COPE, Prof., referred to, 14, 15, 20, 63, 256; quoted, 16. + +Correlation, 171, 184, 211, 222, 268. + +COSTA, M., quoted, 217. + +CUNNINGHAM, Mr. J. T., quoted, 103; referred to, 95, 122. + + +D. + +DALL, Prof., referred to, 14. + +DARWIN, Charles, referred to, 1-13, 20-22, 25, 44, 45, 51-53, 56, 66, +67, 74, 87, 88, 93, 95, 96-100, 149, 159, 160, 167, 173, 174, 181-183, +187-191, 193, 195, 198, 200-202, 213-216, 218, 219, 226, 256, 261-265, +268, 271, 277, 283, 287, 291, 305-307, 313-332, 337; quoted, 11, 53, 66, +96, 181, 182, 186-191, 193, 195, 201, 202, 213-215, 261, 262, 265, +313-316, 319-322, 324-326, 328-331, 337. + +_Darwin et ses Précurseurs Français_, referred to, 234. + +_Darwinian Theory of the Origin of Species_, quoted, 254. + +_Darwinism_, quoted, 22, 27, 67, 181, 182, 186, 189-191, 221, 222, 235, +236, 252, 253, 269, 270, 273, 313, 316; referred to, 7, 12, 15, 20, 70. + +DE CANDOLLE, Prof., referred to, 206. + +Deep-sea faunas, 212. + +DELBÅ’UF, referred to, 224. + +_Descent of Man_, quoted, 25, 322-324, 331. + +_Development of the Hard Parts of the Mammalia_, referred to, 14. + +DE VRIES, Prof., referred to, 122, 174. + +Diagnostic characters of birds, 176; + Marsupials, 178. + +Divergent Evolution through Cumulative Segregation, quoted, 224. + +DIXON, Mr. Charles, referred to, 174; quoted, 177, 223. + +_Doctrine of Descent and Darwinism_, quoted, 260. + +Dogs, scratching, reflex of, 80; + shaking off water, 84; + transplantation of ovaries, 143. + +DORFMEISTER, Dr., referred to, 211. + +Ducks, use-inheritance in, 96; + losing true plumage, 187. + +DUPUY, Dr., referred to, 105. + +DYER, Mr. Thistleton, quoted, 325, 327. + + +E. + +_Effect of External Influences upon Development_, referred to, 66, 95. + +_Effects of Use and Disuse_, quoted, 50. + +EIMER, Prof., referred to, 14, 174, 217. + +_Entomological Society, Trans. of_, quoted, 211; referred to, 217. + +Epilepsy of guinea-pigs, 104. + +_Essays on Heredity_, quoted, 56, 91, 97, 107, 152; referred to, 12, 36, +65, 105, 110. + +EUDES-DESLONGCHAMPS, M., referred to, 188. + +European and American trees, compared, 201. + +EVEREST, Rev. E., quoted, 213. + +_Evolution without Natural Selection_, quoted, 177. + +_Examination of Weismannism_, referred to, 39-42, 44, 100, 122, 123, +134, 136, 138-140, 156. + +_Experiments in Pangenesis_, referred to, 145. + + +F. + +FABRE, M., referred to, 88. + +Factors of organic evolution: + Natural Selection, 2, 5, 6; + use-inheritance, 3, 11. + +_Factors of Organic Evolution_, referred to, 8. + +Faculties and organs, 29. + +Fertility, 229. + +Flat-fish, Mr. Cunningham on, 103. + +_Floral Structures_, referred to, 19. + +FOCKE, Dr., referred to, 174. + +_Fonctions du Cerveau_, referred to, 109. + +Food, influence of, 217. + +Foot, of man, 23. + +Frog, brainless, balancing of, 78. + + +G. + +GALTON, Mr. Francis, referred to, 40-48, 100, 103, 134-139, 145, 146, +152, 154, 156, 300, 303-305; quoted, 46, 100. + +Gangrene, effects of, 54, 105. + +_Gardener's Chronicle_, quoted, 127. + +GÄRTNER, Dr., referred to, 206. + +GEDDES, Prof., referred to, 15, 20,174. + +Gemmules, 47, 145, 155. + +Genera and species, 261. + +Germ-plasm and Stirp, 40; + and pangenesis, 42; + isolation of, 137; + stability of, 243. + +_Germ-plasm_, referred to, 128. + +GIARD, Prof., referred to, 14, 174. + +Giraffe, co-adaptation in, 64. + +GOLTZ, Prof., referred to, 80, 84. + +GOULD, Mr., referred to, 210. + +Graft-hybridization, 143. + +Growth, laws of, 222, 226, 248, 270, 321. + +Guinea-pigs, epilepsy of, 104. + +GULICK, Mr., referred to, 174, 259, 260, 271; quoted, 224, 273. + +_Gute und schlechte Arten_, quoted, 203. + + +H. + +Habit, hereditary, 87. + +_Habit and Intelligence_, quoted, 225. + +Hand, of man, 24. + +_Handbook of British Flora_, referred to, 252. + +HAYCRAFT, Prof., referred to, 80. + +HEAPE, Mr. Walter, referred to, 147. + +HENSLOW, Prof. George, referred to, 18-20, 127-132, 174, 208; quoted, +19, 130, 131. + +Heredity, problems of, 39. + +HERING, Prof., referred to, 87. + +HEWITT, Mr., referred to, 187. + +HILL, Prof. Leonard, quoted, 132. + +HAECKEL, Prof., referred to, 174, 260, 282. + +HOFFMANN, Dr., referred to, 123, 280. + +Horse, callosities of, 265. + +HUXLEY, Prof. T. H., referred to, 167-170, 185, 256, 275, 283, 307-312; +quoted, 307-309. + +Huxleyan doctrine of species, 167. + +_Hyatt_, Prof., referred to, 14, 15. + +Hymenoptera, social, 92. + + +I. + +_Inadequacy of Natural Selection_, referred to, 65, 95. + +_Inconsistencies of Utilitarianism as the Exclusive Theory of Organic +Evolution_, quoted, 273. + +Indifferent characters, 171, 185, 208, 247. + +Insects, instincts of, 91. + +Instability of useless characters, 186. + +Instinct and hereditary habit, 87; + of Sphex, 88; + of carnivora, 89; + of man, 89; + Prof. Weismann's views on, 90; + of insects, 91. + +Intercrossing, 67-71. + +Isolation, 223 _et seq._ + + +J. + +JORDAN, Dr., referred to, 206, 252. + + +K. + +Karyokinesis, 140. + +KERNER, Prof., referred to, 174, 202-206, 231, 239, 260, 282; quoted, +203. + +KOCH, Dr., referred to, 217. + +KÖLLIKER, Prof., referred to, 174. + + +L. + +Lamarck, referred to, 9-15. + +Lamarckism, 9, 61, 113. + +LANDOR, A. H. Savage, referred to, 26. + +Language and Weismannism, 334. + +LANKESTER, Prof. Ray, quoted, 245, 299; referred to, 305. + +LESAGE, M., referred to, 126. + +_Life and Letters of Charles Darwin_, quoted, 319, 320; referred to, 11. + +LUCIANI, referred to, 109. + + +M. + +_Making of Flowers_, referred to, 19. + +_Manual of British Botany_, referred to, 252. + +_Manual of Dental Anatomy_, figure from, 267. + +Marsupials, diagnostic characters of, 178. + +_Materials for the Study of Variation_, referred to, 36. + +MEEHAN, Mr., referred to, 201. + +MELDOLA, Prof., referred to, 68. + +_Mental Evolution in Animals_, referred to, 25, 88, 89, 92. + +_Mental Evolution in Man_, referred to, 31. + +MERRIFIELD, Mr., referred to, 211. + +Mice, mutilation of tails of, 148. + +MIVART, Prof. St. George, referred to, 4, 174, 217. + +Monstrosity, in turkeys, 181; + in cattle, 196. + +MORGAN, Prof. Lloyd, referred to, 33, 36, 174, 271, 300-305; quoted, +300, 303. + +MOSELEY, Prof., referred to, 26. + +MURPHY, Mr. J. J., referred to, 224. + +Mutilations, inheritance of, 53, 148. + + +N. + +NÄGELI, Prof., referred to, 174, 206, 318. + +Naked skin of man, 25. + +NATHUSIUS, referred to, 188. + +Natural Selection, range of, 2, 5, 51, 62, 92; + a theory of species, 161, 169; + and cave animals, 211; + and Porto Santo rabbits, 214. + +_Natural Selection and Tropical Nature_, quoted, 23. + +_Natural Science_, quoted, 104. + +_Nature_, quoted, 132, 223, 245, 299, 325; referred to, 68, 98, 218. + +Neo-Darwinian school, 10, 61. + +Neo-Lamarckian school, 13, 62, 63. + +_Neuer Beitrag zum geologischen Beweis der Darwin'schen Theorie_, +quoted, 254. + +_Neuter Insects and Darwinism_, referred to, 95. + +_Neuter Insects and Lamarckism_, referred to, 95. + +Neuters of hymenopterous insects, 92. + +NEWMAN, Cardinal, referred to, 20. + +Niata cattle, 191. + + +O. + +OBERSTEINER, Dr., referred to, 105, 106. + +_Oesterreichische medicinische Jahrbücher_, referred to, 105. + +_On Truth_, referred to, 217. + +Orang-utan, teeth of, 267. + +_Organic Evolution_, referred to, 217. + +_Origin of the Fittest_, quoted, 16; referred to, 14. + +_Origine des Plantes Domestiques, démontrée par la culture du Radis +sauvage_, referred to, 123. + +_Origin of Sex_, referred to, 17. + +_Origin of Species_, quoted, 3, 4, 181, 182, 186, 188, 190, 261, 262, +265, 321, 322, 325, 326, 329; referred to, 67, 159, 227, 286. + +OSBORN, Prof., referred to, 14, 58, 63. + +OWEN, Sir Richard, referred to, 191. + +Oxen, skulls of, compared, 192. + +Oysters, change of, 217. + + +P. + +PACKARD, Prof., referred to, 14, 213. + +Pangenesis, 11, 42. + +Panmixia, 97, 212, 291. + +Parsimony, law of, 51. + +Parsnips, variation of, 125. + +PASCOE, Mr., referred to, 174; quoted, 254. + +PERRIER, Prof., referred to, 14, 93, 95. + +PETER, Dr., referred to, 206. + +PFEFFER, Herr, referred to, 15. + +_Pflüger's Archiv_, referred to, 80. + +_Philosophical Transactions_, referred 10, 103. + +_Physiological Selection_, referred to, 187, 307, 313, 324; quoted, 188, +308. + +_Pickard-Cambridge_, Rev. O., quoted, 221. + +Pig, old Irish, 188. + +Plants, influence of climate on, 122-207. + +Porto Santo rabbits, 214. + +POULTON, E. B., referred to, 36, 217, 337. + +_Presidential Address to the Bristol Naturalists Society_, 1891; quoted, +300, 303. + +_Proceedings of the Royal Society_, referred to, 145, 147; quoted, 307. + +Protective resemblance, 72. + +Protrusion of eyeball, in epileptic guinea-pigs, 111. + + +Q. + +QUATREFAGES, M., referred to, 234. + + +R. + +Rabbits, and use-inheritance, 96; + transplantation of ovaries, 143; + Porto Santo, 214. + +Radish, variation of, 123. + +Rats, scratching, reflex of, 81. + +_Raupen und Schmetterlinge der Wetterau_, referred to, 217. + +Reflex action and use-inheritance, 64-87. + +_Rejoinder to Prof. Weismann_, referred to, 95. + +Reversal of selection, 101, 292. + +_Revue Générale de Botanie_, referred to, 126. + +RICHARDSON, referred to, 188. + +ROUX, Prof., referred to, 298. + +Rudiments, 294. + +RYDER, Prof., referred to, 14. + + +S. + +SACHS, Prof., referred to, 15, 174. + +"Sally," counting of, 31. + +SAUERMANN, Dr., referred to, 218. + +SCHÄFER, Prof., referred to, 145. + +_Schmetterlinge des Südwestlichen Deutschlands_, referred to, 217. + +SCHMIDT, Dr. Oscar, quoted, 260. + +Schools of Evolutionists, 12-20. + +SCOTT, Prof., referred to, 63. + +Scratching, reflex, in dogs, 80; + in rats, 81. + +Seasonal changes of butterflies, 210. + +SEEBOHM, Mr. Henry, quoted, 173; referred to, 174. + +Selection, cessation of, 99, 292; + reversal of, 101, 292. + +Selection, sexual, 219 _et seq._ + +Selective value, 73. + +Self-adaptation, 18. + +SEMPER, Prof. Karl, referred to, 101. + +Sexual selection, 219 _et seq._ + +Sole, pigment of, 104. + +Somatogenetic and somatoplasm, 123, 137, 155, 242-249. + +_Some Laws of Heredity_, referred to, 24. + +Species, stress laid on origin of, 159; + necessarily due to natural selection, 168. + +---- definitions of, 229. + +SPENCER, Herbert, referred to, 8, 64-68, 95. + +Sphex, instincts of, 88, 337. + +STEBBING, Rev. T. R., quoted, 25. + +Sterility, 8. + +Stirp and germ-plasm, 40, 47, 138. + +_Struggle for Existence between the parts of an Organism_, referred to, +299. + + +T. + +Theory of Heredity, referred to, 40, 47, 137, 154; quoted, 46, 47. + +THOMAS, Mr. Oldfield, referred to, 178. + +THOMSON, J. A., referred to, 15. + +TODD, J. E., referred to, 35. + +TOMES, Mr., referred to, 267. + +Transfusion of blood in rabbits, 145. + +Transplantation of ovaries in rabbits, 143, 147. + +Trees, comparison of European and American, 201. + +Turkey, tuft of hair of, 181; + losing metallic tints, 186. + + +U. + +Use-inheritance, 3, 49, 77, 95, 151. + +Utility, law of, 8, 20, 159; + universality of, 166; + of specific characters, 172; + of specific characters in birds, 176; + of specific characters in Mammals, 178. + + +V. + +_Variation of Animals and Plants under Domestication_, quoted, 3, 4, 53, +66, 96, 187, 189, 191, 193, 195, 213-216, 330, 331. + +Varieties, climatic, 228. + +Vestigial characters, 171, 184, 261, 294. + +VINES, Prof., referred to, 297. + +Vitality, plumes of birds due to surplus, 270, 25. + +Voice, of man, 25. + + +W. + +WAGNER, Moritz, referred to, 217. + +WALLACE, Mr. A. R., referred to, 2, 6, 9, 11, 15, 20-35, 50, 66-70, 167, +169, 172-175, 180-198, 210, 218-227, 235-237, 252, 256, 258, 263-278, +285, 313-322, 328, 331, 332; quoted, 22-24, 27, 67, 180-182, 185, 186, +190, 191, 221-223, 235, 236, 269, 273, 313. + +Wallacean doctrine of species, 167, 169. + +WEISMANN, Prof., referred to, 2, 7, 9, 12, 13, 39-60, 65, 66, 90-105, +112, 128, 134-142, 148, 149, 151, 152, 155, 156, 173, 241, 243, 244, +246, 279, 280, 291, 294, 297, 298, 300, 311, 338; quoted, 56, 91, 97, +152, 243, 244, 297. + +Weismannism, diagram of constituent theories, 43, 136; + elusiveness of, 334. + +_Weismannism once more_, referred to, 66, 95. + +WELBY, Hon. Lady, referred to, 90. + +WESTPHAL, Prof., referred to, 105, 107. + +Withdrawal of foot by reflex action, 75. + +WÃœRTENBERGER, Dr., referred to, 254. + + +Y. + +YARRELL, Mr., referred to, 186. + + + + +LIST OF OPEN COURT PUBLICATIONS ON SCIENCE + + +The Primary Factors of Organic Evolution. By E. D. Cope. Second +edition. Pages, 550; illustrations, 121; tables, bibliography, and +index. Cloth, $2.00 net. + + A comprehensive handbook of the Neo-Lamarckian theory of Evolution. + + +A Mechanico-Physiological Theory of Organic Evolution. By Carl von +Naegeli. Translated by V. A. Clark and F. A. Waugh. Price, cloth, 60c; +paper, 30c net. + + A synopsis of his great work on evolution. + + +Darwin and After Darwin. An exposition of the Darwinian Theory and a +Discussion of Post-Darwinian Questions. By George J. Romanes. 3 vols. +Price, $4.00 net. + +Part I. The Darwinian Theory. Price, cloth, $2.00 net. + +Part II. Post-Darwinian Questions: Heredity and Utility. Price, cloth, +$1.50 net. + +Part III. Post-Darwinian Questions. Isolation and Physiological +Selection. Price, cloth, $1.00 net. + + +An Examination of Weismannism. By George J. Romanes. Price, cloth, +$1.00 net; paper, 40c net. + + "The best criticism of the subject in our language."--_The + Outlook._ + + +On Germinal Selection. By August Weismann. Translated by T. J. +McCormack. Price, paper, 30c net. + + +The Rise of Man. A Sketch of the Origin of the Human Race. By Paul +Carus. Pages, 97; illustrated. Boards, cloth back, 75c net. + + +The Scope and Content of the Science of Anthropology. By Juul +Dieserud. Pages, 200; cloth, gilt top, $2.00 net. + + "The science of Anthropology," according to Topinard, "is that + branch of natural history which treats of man, and the races of + men." + + +Experiments on the Generation of Insects. By Francesco Redi. +Translated from the Italian edition of 1688, by Mab Bigelow. +Illustrated. Cloth, $2.00 net. + + This book may be counted as one of the classics of the theory of + evolution. + + +Ants and Some Other Insects. An Inquiry into the Psychic Powers of +these Animals, with an Appendix on the peculiarities of their Olfactory +Sense. By August Forel. Translated by William M. Wheeler. Price, +$1.00 net; paper, 55c net. + + +Plant Breeding. Comments on the Experiments of Nilsson and Burbank. By +Hugo de Vries. Pages, xv, 360. Illustrated with 114 half-tone plates +from nature. Printed on fine paper, in large type. Cloth, gilt top. +Price, $1.50 net. + + A scientific book in simple language. Intensely interesting as well + as instructive. Of special value to every botanist, horticulturist + and farmer. + + +Species and Varieties, Their Origin by Mutation. Lectures delivered at +the University of California by Hugo de Vries, Professor of Botany in +the University of Amsterdam. Pages, xviii, 847. Cloth, gilt top, $5.00 +net. + + +The Mutation Theory. Experiments and Observations on the Origin of +Species in the Vegetable Kingdom. 2 vols. Numerous illustrations, +colored plates. By Hugo de Vries. Translated by Prof. A. B. Farmer +and A. D. Darbishire. Cloth, per volume, $4.00. + + This is de Vries' great book on a new explanation of the evolution + theory, accounting for the formation of species not by the struggle + for existence but by mutation. + + +Intracellular Pangenesis. Including a paper on Fertilization and +Hybridization. By Hugo de Vries. Translated from the German by C. +Stuart Gager. Cloth, $3.00 net. + + This is de Vries' first important book. It is not very large, but + ought to be read by all students of botany, and also by those who + are interested in the theory of evolution. + + +On Orthogenesis and the Impotence of Natural Selection in +Species-Formation. By Th. Eimer. Translated by T. J. McCormack. +Price, paper, 30c net. + + Another critic of Darwin who claims that organisms develop through + transmission of acquired characters. + + +On the Inheritance of Acquired Characters. By Eugenio Rignano. +Translated by Basil C. H. Harvey. With an Appendix "On the Mnemonic +Origin and Nature of Affective Tendencies." Cloth, $3.00 net. + + Rignano calls his theory "centro-epigenesis" and is greatly + influenced by Weismann. + + +On Double Consciousness. Studies in Experimental Psychology. By +Alfred Binet. Third edition. Pages, 93. Cloth, 50c net; paper, 20c +net. + + "A most valuable contribution to this important subject which none + of its students can afford to leave unread."--_Public Opinion._ + + +The Psychic Life of Micro-Organisms. By Alfred Binet. Authorized +translation. Pages, xii, 120. Cloth, 75c net; paper, 30c net. + + "He fortifies his theory by such a wealth of exact observation and + experiments that the reader who follows his demonstration carefully + can hardly fail of conviction."--_New York Tribune._ + + +The Psychology of Reasoning. By Alfred Binet. Translated from the +second French edition by Adam Gowans Whyte, B.Sc. Pages, 191. Cloth, +75c net; paper, 30c net. + + "Like everything that Dr. Binet writes, the subject is stated and + expounded lucidly."--_The Lancet._ + + +The Diseases of Personality. By Théodule Ribot. Authorized +translation. Fourth edition. Pages, 157. Cloth, 75c net; paper, 30c. + + Contents: Introduction, Consciousness; Organic Disorders; Affective + Disorders; Diseases of the Intellect; Dissolution of Personality. + + +The Diseases of the Will. By Théodule Ribot. Authorized translation. +Third edition. Pages, vi, 121. Cloth, 75c net; paper, 30c net. + + Contains chapters on impairments of the will and of voluntary + attention, the realm of caprices, and extinction of the will. + + +Essay on the Creative Imagination. By Théodule Ribot. Translated +from the French by A. H. N. Baron, Fellow in Clark University. Cloth, +gilt top. Pages, 357. $1.75 net. + + The motor nature of the constructive imagination. + + +The Psychology of Attention. By Théodule Ribot, Professor in the +Collège de France and editor of the "Revue Philosophique." Fifth and +revised edition. Authorized translation. Pages, 121. Cloth, 75c net; +paper, 30c net. + + Contents: Spontaneous or Natural Attention; Voluntary or Artificial + Attention; Morbid States of Attention. + + +The Diseases of Memory. By Théodule Ribot. Cloth, $1.50 net. + + +Memory. Lectures on the Specific Energies of the Nervous System. By +Ewald Hering. Fourth edition, containing an additional chapter on the +Theory of Nerve Activity. Cloth, $1.00 net. + + +The Analysis of Sensations and the Relation of the Physical to the +Psychical. By Ernst Mach, Emeritus Professor in the University of +Vienna. Translated by C. M. Williams. Third edition revised and +supplemented from the fifth German edition by Sydney Waterlow, M.A. +Pages, xvi, 380. Cuts, 37. Cloth, $1.50 net. + + +Popular Science Lectures. By Ernst Mach, Professor in the University +of Vienna. Translated from the German by T. J. McCormack. Third +edition. Pages, 415. Cloth, gilt top, $1.50 net; paper, 60c net. + + A portrayal of the methods and spirit of science, in lectures on + mechanics, sound, light, electricity, the conservation of energy, + philosophy and education. + + +Man a Machine. By Julien Offray De La Mettrie. Including Frederick +the Great's Eulogy on La Mettrie and Extracts from La Mettrie's "Natural +History of the Soul." Translated, with notes, by Gertrude Carman +Bussey. French-English edition. With a portrait of La Mettrie. Pages, +226. Cloth, $2.00 net. + + La Mettrie was the most extreme writer among the earliest French + materialists. His doctrine is an extension to man of Descartes' + doctrine that animals are automata. + + + + +PORTRAITS + +Philosophical and Psychological Portrait Series + + +Printed on large paper (11 × 14) with tint and platemark. Many of them +are reproduced from rare paintings, engravings, or original photographs. +They are suitable for framing and hanging in public and private +libraries, laboratories, seminaries, recitation and lecture rooms, and +will be of interest to all concerned in education and general culture. + + +PHILOSOPHICAL + +Pythagoras +Socrates +Plato +Aristotle +Epictetus +Thomas Aquinas +St. Augustine +Averrhoes +Duns Scotus +Giordano Bruno +Bacon +Hobbes +Descartes +Malebranche +Herbert Spencer +Schelling +Spinoza +Locke +Berkeley +Hume +Montesquieu +Voltaire +D'Alembert +Condillac +Diderot +Rousseau +Leibniz +Wolff +Kant +Fichte +Hegel +Schleiermacher +Schopenhauer +Herbart +Feuerbach +Lotze +Reid +Dugald Stewart +Sir W. Hamilton +Cousin +Comte +Rosmini +J. Stuart Mill + + +PSYCHOLOGICAL + +Cabanis +Maine de Biran +Beneke +E. H. Weber +Fechner +Helmholtz +Wundt +Hering +G. T. Ladd +Aubert +Mach +Stumpf +Exner +Steinthal +Bain +Sully +Ward +C. L. Morgan +Romanes +Paul Janet +Ribot +Taine +Fouillée +Binet +G. Stanley Hall + + +PRICES: + +Philosophical and Psychological Portrait Series. + + 68 portraits on plate paper, $7.50 per set net. On Japanese vellum, + $12.50 per set net. + +Philosophical Portrait Series. + + No. 100. 43 portraits on plate paper, $6.25 per set net. + + No. 100a. 43 portraits on Japanese vellum, $8.75 per set net. + + Single portraits on American plate, 25c net. + + Single portraits on Japanese vellum, 35c net. + + +Psychological Portrait Series. + + No. 101. 25 portraits on plate paper, $3.75 net. + + No. 101a. 25 portraits on Japanese vellum, $5.00 net. + + Single portraits on American plate, 25c net. + + Single portraits on Japanese vellum, 35c net. + + +Framing Portrait of Hugo de Vries. + + Platino finish. 10" × 12", unmounted, $1.00 net. + + +Framing Portrait of William James. + + Printed on Japan paper. 11" × 14", $1.00. + + +Portraits of Eminent Mathematicians + +Three portfolios edited by David Eugene Smith, Professor of Mathematics +in Teachers' College, Columbia University, New York. + +In response to a widespread demand from those interested in mathematics +and the history of education, Professor Smith has edited three +portfolios of the portraits of some of the most eminent of the world's +contributors to the mathematical sciences. Accompanying each portrait is +a brief biographical sketch, with occasional notes of interest +concerning the artist represented. The pictures are of a size that +allows for framing (11" × 14"), it being the hope that a new interest in +mathematics may be aroused through the decoration of classrooms by the +portraits of those who helped to create the science. + +Portfolio No. 1.--Twelve great mathematicians down to 1700 A.D.: Thales, +Pythagorus, Euclid, Archimedes, Leonardo of Pisa, Cardan, Vieta, Napier, +Descartes, Fermat, Newton, Leibniz. + +Portfolio No. 2.--The most eminent founders and promotors of the +infinitesimal calculus: Cavallieri, Johann and Jakob Bernoulli, Pascal, +L'Hopital, Barrow, Laplace, Lagrange, Euler, Gauss, Monge, and Niccolo +Tartaglia. + +Portfolio No. 3--Eight portraits selected from the two former +portfolios, especially adapted for high schools and academies, +comprising portraits of + + Thales--with whom began the study of scientific geometry; + + Pythagoras--who proved the proposition of the square on the + hypotenuse; + + Euclid--whose Elements of Geometry form the basis of all modern + text-books; + + Archimedes--whose treatment of the circle, cone, cylinder and sphere + influences our work today; + + Descartes--to whom we are indebted for the graphic algebra in our + high schools; + + Newton--who generalized the binomial theorem and invented the + calculus; + + Napier--who invented logarithms and contributed to trigonometry; + + Pascal--who discovered the "Mystic Hexagram" at the age of sixteen. + + +Portraits of Mathematicians, Part I. + + No. 102. 12 portraits on American plate paper, $3.00 net. + + No. 102a. 12 portraits on Japanese vellum, $5.00 net. + + Single portraits, American plate, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +Portraits of Mathematicians, Part II. + + No. 103. 12 portraits on American plate paper, $3.00 net. + + No. 103a. 12 portraits on Japanese vellum, $5.00 net. + + Single portraits, American plate paper, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +Portraits of Mathematicians, High School Portfolio. + + Eight portraits selected from the two preceding portfolios. + + No. 104. 8 portraits on American plate paper, $2.00 net. + + No. 104a. 8 portraits on Japanese vellum, $3.50 net. + + Single portraits, American plate paper, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +_For Purchasers who may prefer not to frame the Portraits, a neat +Portfolio can be supplied at an extra cost of $1.00._ + + + + + * * * * * + + + + +Transcriber's note: + +The following typographical errors were correctred. + + |Page |Error |Correction | + |10 |dicussion |discussion | + |45 |thoughout |throughout | + |229 |pyschological |psychological | + +The following inconsistent hyphenations were changed. + + |Page |Original |Changed to | + |34 |inter-crossing |intercrossing | + |46 |re-appear |reappear | + |123 |re-act |react | + |132 |eye-lid |eyelid | + |216 |lifetimes |life-times | + |217 |lifetime |life-time | + |317 |threefold |three-fold | + +The following inconsistent hyphenations were not changed. + + "somatoplasm" (3 instances) and "somato-plasm" (2 instances) + "twofold" (2) and "two-fold" (1) + "interaction" (1) and "inter-action" (1) + "supernatural" (1) and "super-natural" (1) + +Other changes: + + Page 16 Footnote 10 - double quotes around "acceleration" and + "retardation" changed to single quotes. A double quote inserted at + the end. + + In the Index - Entries "On Truth" and "Orang-utan, teeth of" moved + from under "M" to under "O". + + + +***END OF THE PROJECT GUTENBERG EBOOK DARWIN, AND AFTER DARWIN, VOLUME II +(OF 3)*** + + +******* This file should be named 37759-0.txt or 37759-0.zip ******* + + +This and all associated files of various formats will be found in: +http://www.gutenberg.org/dirs/3/7/7/5/37759 + + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://www.gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS', WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.gutenberg.org/fundraising/pglaf. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://www.gutenberg.org/about/contact + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://www.gutenberg.org/fundraising/donate + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: +http://www.gutenberg.org/fundraising/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. + diff --git a/37759-0.zip b/37759-0.zip Binary files differnew file mode 100644 index 0000000..7a6a35e --- /dev/null +++ b/37759-0.zip diff --git a/37759-8.txt b/37759-8.txt new file mode 100644 index 0000000..a707b7e --- /dev/null +++ b/37759-8.txt @@ -0,0 +1,11467 @@ +The Project Gutenberg eBook, Darwin, and After Darwin, Volume II (of 3), +by George John Romanes + + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + + + + +Title: Darwin, and After Darwin, Volume II (of 3) + Post-Darwinian Questions: Heredity and Utility + + +Author: George John Romanes + + + +Release Date: October 15, 2011 [eBook #37759] + +Language: English + +Character set encoding: ISO-8859-1 + + +***START OF THE PROJECT GUTENBERG EBOOK DARWIN, AND AFTER DARWIN, VOLUME +II (OF 3)*** + + +E-text prepared by Marilynda Fraser-Cunliffe, L. N. Yaddanapudi, and the +Online Distributed Proofreading Team (http://www.pgdp.net) + + + +Note: Project Gutenberg also has an HTML version of this + file which includes the original illustrations. + See 37759-h.htm or 37759-h.zip: + (http://www.gutenberg.org/files/37759/37759-h/37759-h.htm) + or + (http://www.gutenberg.org/files/37759/37759-h.zip) + + + + + +DARWIN, AND AFTER DARWIN + +II + +Post-Darwinian Questions + +Heredity and Utility + + * * * * * + + +BY THE SAME AUTHOR. + + + DARWIN AND AFTER DARWIN. An Exposition of the Darwinian Theory and a + Discussion of Post-Darwinian Questions. + 1. THE DARWINIAN THEORY. 460 pages. 125 illustrations. Cloth, + $2.00. + 2. POST-DARWINIAN QUESTIONS. Edited by Prof. C. Lloyd Morgan. + 338 pages. Cloth, $1.50. Both volumes together, $3.00 net. + + AN EXAMINATION OF WEISMANNISM. 236 pages. Cloth, $1.00. + + THOUGHTS ON RELIGION. Edited by Charles Gore, M.A., Canon of + Westminster. Second Edition. 184 pages. Cloth, gilt top, $1.25. + + +THE OPEN COURT PUBLISHING COMPANY, +324 DEARBORN STREET, CHICAGO. + + * * * * * + + +[Illustration: Frontispiece] + + +DARWIN, AND AFTER DARWIN + +AN EXPOSITION OF THE DARWINIAN THEORY +AND A DISCUSSION OF POST-DARWINIAN QUESTIONS + +by the Late + +GEORGE JOHN ROMANES, M.A., LL.D., F.R.S. +Honorary Fellow of Gonville and Caius College, Cambridge + +II + +Post-Darwinian Questions +Heredity and Utility + +FOURTH EDITION + + + + + + + +Chicago London +The Open Court Publishing Company +1916 + +Chapter 1 Copyrighted by +The Open Court Publishing Co. +Chicago, Ill., 1895 + +Printed in the +United States of America + + + + +PREFACE + + +As its sub-title announces, the present volume is mainly devoted to a +consideration of those Post-Darwinian Theories which involve fundamental +questions of Heredity and Utility. + +As regards Heredity, I have restricted the discussion almost exclusively +to Professor Weismann's views, partly because he is at present by far +the most important writer upon this subject, and partly because his +views with regard to it raise with most distinctness the issue which +lies at the base of all Post-Darwinian speculation touching this +subject--the issue as to the inheritance or non-inheritance of acquired +characters. + +My examination of the Utility question may well seem to the general +reader needlessly elaborate; for to such a reader it can scarcely fail +to appear that the doctrine which I am assailing has been broken to +fragments long before the criticism has drawn to a close. But from my +previous experience of the hardness with which this fallacious doctrine +dies, I do not deem it safe to allow even one fragment of it to remain, +lest, hydra-like, it should re-develop into its former proportions. And +I can scarcely think that naturalists who know the growing prevalence of +the doctrine, and who may have followed the issues of previous +discussions with regard to it, will accuse me of being more over-zealous +in my attempt to make a full end thereof. + +One more remark. It is a misfortune attending the aim and scope of Part +II that they bring me into frequent discord with one or other of the +most eminent of Post-Darwinian writers--especially with Mr. Wallace. But +such is the case only because the subject-matter of this volume is +avowedly restricted to debateable topics, and because I choose those +naturalists who are deservedly held in most esteem to act spokesmen on +behalf of such Post-Darwinian views as appear to me doubtful or +erroneous. Obviously, however, differences of opinion on particular +points ought not to be taken as implying any failure on my part to +recognize the general scientific authority of these men, or any +inability to appreciate their labours in the varied fields of Biology. + +G. J. R. +CHRIST CHURCH, OXFORD. + + + + +NOTE + +Some time before his death Mr. Romanes decided to publish those sections +of his work which deal with Heredity and Utility, as a separate volume, +leaving Isolation and Physiological Selection for the third and +concluding part of _Darwin, and after Darwin_. + +Most of the matter contained in this part was already in type, but was +not finally corrected for the press. The alterations made therein are +for the most part verbal. + +Chapter IV was type-written; in it, too, no alterations of any moment +have been made. + +For Chapters V and VI there were notes and isolated paragraphs not yet +arranged. I had promised during his life to write for Mr. Romanes +Chapter V on the basis of these notes, extending it in such ways as +seemed to be desirable. In that case it would have been revised and +amended by the author and received his final sanction. Death annulled +this friendly compact; and since, had I written the chapter myself, it +could not receive that imprimatur which would have given its chief +value, I have decided to arrange the material that passed into my hands +without adding anything of importance thereto. The substance of Chapters +V and VI is therefore entirely the author's: even the phraseology is +his; the arrangement only is by another hand. + +Such parts of the Preface as more particularly refer to Isolation and +Physiological Selection are reserved for publication in Part III. A year +or more must elapse before that part will be ready for publication. + +Mr. F. Howard Collins has, as a kindly tribute to the memory of the +author, read through the proofs. Messrs. F. Darwin, F. Galton, H. +Seebohm, and others, have rendered incidental assistance. After much +search I am unable to give the references to one or two passages. + +I have allowed a too flattering reference to myself to stand, in +accordance with a particular injunction of Mr. Romanes given shortly +before that sad day on which he died, leaving many to mourn the loss of +a personal friend most bright, lovable, and generous-hearted, and +thousands to regret that the hand which had written so much for them +would write for them no more. + +C. LL. M. + +UNIVERSITY COLLEGE, BRISTOL, +_April, 1894_. + + + + +CONTENTS + + PAGE +CHAPTER I. +INTRODUCTORY: THE DARWINISM OF DARWIN AND OF THE +POST-DARWINIAN SCHOOLS 1 + +CHAPTER II. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Preliminary_) 39 + +CHAPTER III. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + A. _Indirect evidence in favour of the Inheritance of Acquired + Characters_ 60 + B. _Inherited effects of Use and of Disuse_ 95 + +CHAPTER IV. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + C. _Experimental evidence in favour of the Inheritance of Acquired + Characters_ 103 + +CHAPTER V. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + A. and B. _Direct and Indirect Evidence in favour of the + Non-inheritance of Acquired Characters_ 133 + + C. _Experimental Evidence as to the Non-inheritance of Acquired + Characters_ 142 + +CHAPTER VI. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Conclusion_) 150 + +CHAPTER VII. +CHARACTERS AS ADAPTIVE AND SPECIFIC 159 + +CHAPTER VIII. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Continued_) + I. _Climate_ 200 + II. _Food_ 217 + III. _Sexual Selection_ 219 + IV. _Isolation_ 223 + V. _Laws of Growth_ 226 + +CHAPTER IX. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Continued_) 228 + +CHAPTER X. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Concluded_) 251 + SUMMARY 274 + +APPENDIX I. ON PANMIXIA 291 + +APPENDIX II. ON CHARACTERS AS ADAPTIVE AND SPECIFIC 307 + +NOTE A TO PAGE 57 333 + +NOTE B TO PAGE 89 337 + + + + +LIST OF ILLUSTRATIONS + + PAGE + +Portrait of George John Romanes _Frontispiece_ + +Diagram of Prof. Weismann's Theories 43 + +FIG. 1. Guinea pigs, showing gangrene of ears due to injury of + restiform bodies 118 + +FIG. 2. Old Irish Pig (after Richardson) 188 + +FIG. 3. Skulls of Niata Ox and of Wild White Ox 192 + +FIG. 4. Lower teeth of Orang (after Tomes) 261 + + + + +CHAPTER I. + +INTRODUCTORY: THE DARWINISM OF DARWIN, AND OF THE POST-DARWINIAN +SCHOOLS. + + +It is desirable to open this volume of the treatise on _Darwin and after +Darwin_ by taking a brief survey of the general theory of descent, +first, as this was held by Darwin himself, and next, as it is now held +by the several divergent schools of thought which have arisen since +Darwin's death. + +The most important of the questions in debate is one which I have +already had occasion to mention, while dealing, in historical order, +with the objections that were brought against the theory of natural +selection during the life-time of Darwin[1]. Here, however, we must +consider it somewhat more in detail, and justify by quotation what was +previously said regarding the very definite nature of his utterances +upon the matter. This question is whether natural selection has been the +sole, or but the main, cause of organic evolution. + + [1] Part I, pp. 253-256. + +Must we regard survival of the fittest as the one and only principle +which has been concerned in the progressive modification of living +forms, or are we to suppose that this great and leading principle has +been assisted by other and subordinate principles, without the +co-operation of which the results, as presented in the animal and +vegetable kingdoms, could not have been effected? Now Darwin's answer to +this question was distinct and unequivocal. He stoutly resisted the +doctrine that natural selection was to be regarded as the only cause of +organic evolution. On the other hand, this opinion was--and still +continues to be--persistently maintained by Mr. Wallace; and it +constitutes the source of all the differences between his views and +those of Darwin. Moreover, up to the time of Darwin's death, Mr. Wallace +was absolutely alone in maintaining this opinion: the whole body of +scientific thought throughout the world being against him; for it was +deemed improbable that, in the enormously complex and endlessly varied +processes of organic evolution, only a single principle should be +everywhere and exclusively concerned[2]. But since Darwin's death there +has been a great revolution of biological thought in favour of Mr. +Wallace's opinion. And the reason for this revolution has been, that his +doctrine of natural selection as the sole cause of organic evolution has +received the corroborative support of Professor Weismann's theory of +heredity--which has been more or less cordially embraced by a certain +section of evolutionists, and which appears to carry the doctrine in +question as a logical corollary, so far, at all events, as adaptive +structures are concerned. + + [2] _Contributions to the Theory of Natural Selection_, p. 47. + +Now in this opening chapter we shall have to do merely with a setting +forth of Darwin's opinion: we are not considering how far that opinion +ought to be regarded as having been in any measure displaced by the +results of more recent progress. Such, then, being the only matter which +here concerns us, I will supply a few brief quotations, to show how +unequivocally Darwin has stated his views. First, we may take what he +says upon the "Lamarckian factors[3];" and next we may consider what he +says with regard to other factors, or, in general, upon natural +selection not being the sole cause of organic evolution. + + [3] So far as we shall be concerned with them throughout this + treatise, the "Lamarckian factors" consist in the supposed + transmission of acquired characters, whether the latter be due + to the direct influence of external conditions of life on the + one hand, or to the inherited effects of use and disuse on the + other. For the phrase "inherited effects of use and disuse," I + shall frequently employ the term "use-inheritance," which has + been coined by Mr. Platt Ball as a more convenient expression. + + "Changed habits produce an inherited effect, as in the period of + the flowering of plants when transported from one climate to + another. With animals the increased use or disuse of parts has had + a more marked influence[4]." + + [4] _Origin of Species_, 6th ed. p. 8. + + "There can be no doubt, from the facts given in this chapter, that + extremely slight changes in the conditions of life sometimes, + probably often, act in a definite manner on our domesticated + productions; and, as the action of changed conditions in causing + indefinite variability is accumulative, so it may be with their + definite action. Hence considerable and definite modifications of + structure probably follow from altered conditions acting during + long series of generations[5]." + + [5] _Variation_ &c. 2nd ed. ii. p. 280. + + "How, again, can we explain the inherited effects of the use and + disuse of particular organs? The domesticated duck flies less and + walks more than the wild duck, and its limb bones have become + diminished and increased in a corresponding manner in comparison + with those of the wild duck. A horse is trained to certain paces, + and the colt inherits similar consensual movements. The + domesticated rabbit becomes tame from close confinement; the dog, + intelligent from associating with man; the retriever is taught to + fetch and carry; and these mental endowments and bodily powers are + all inherited. Nothing in the whole circuit of physiology is more + wonderful. How can the use or disuse of a particular limb or of the + brain affect a small aggregate of reproductive cells, seated in a + distant part of the body, in such a manner that the being developed + from these cells inherits the characters of either one or both + parents?... In the chapters devoted to inheritance, it was shown + that a multitude of newly acquired characters, whether injurious or + beneficial, whether of the lowest or highest vital importance, are + often faithfully transmitted[6]." + + [6] _Variation_ &c. ii. p. 367. + + "When discussing special cases, Mr. Mivart passes over the effects + of the increased use and disuse of parts, which I have always + maintained to be highly important, and have treated in my + 'Variation under Domestication' at greater length than, as I + believe, any other writer[7]." + + [7] _Origin of Species_, p. 176. + +So much for the matured opinion of Darwin touching the validity of the +theory of use-inheritance. Turning now to his opinion on the question +whether or not there are yet any further factors concerned in the +process of organic evolution, I think it will be sufficient to quote a +single passage from the _Origin of Species_. The first paragraph of the +"Conclusion" is devoted to a _résumé_ of his views upon this matter, and +consists of the following most emphatic words. + + "I have now recapitulated the facts and considerations which have + thoroughly convinced me that species have been modified, during a + long course of descent. This has been effected chiefly through the + natural selection of numerous successive, slight, favourable + variations; aided in an important manner by the inherited effects + of the use and disuse of parts; and in an unimportant manner, that + is in relation to adaptive structures, whether past or present, by + the direct action of external conditions, and by variations which + seem to us in our ignorance to arise spontaneously. It appears that + I formerly underrated the frequency and value of these latter forms + of variation, as leading to permanent modifications of structure + independently of natural selection. But as my conclusions have + lately been much misrepresented, and it has been stated that I + attribute the modification of species exclusively to natural + selection, I may be permitted to remark that in the first edition + of this work, and subsequently, I placed in a most conspicuous + position--namely, at the close of the Introduction--the following + words: 'I am convinced that natural selection has been the main, + but not the exclusive means of modification.' This has been of no + avail. Great is the power of steady misrepresentation; but the + history of science shows that fortunately this power does not long + endure." + +In the whole range of Darwin's writings there cannot be found a passage +so strongly worded as this: it presents the only note of bitterness in +all the thousands of pages which he has published. Therefore I do not +think it is necessary to supply any further quotations for the purpose +of proving the state of his opinion upon the point in question. But, be +it carefully noted, from this great or radical difference of opinion +between the joint originators of the theory of natural selection, all +their other differences of opinion arise; and seeing that since the +death of Darwin a large number of naturalists have gone over to the side +of Wallace, it seems desirable here to state categorically what these +other or sequent points of difference are. Without at present discussing +them, therefore, I will merely set them out in a tabular form, in order +that a clear perception may be gained of their logical connexion with +this primary point of difference. + + |_The Theory of Natural |_The theory of Natural | + |Selection according to |Selection according to | + |Darwin._ |Wallace._ | + | | | + |Natural Selection has been |Natural Selection has been | + |the main means of |the sole means of | + |modification, not excepting |modification, excepting in | + |the case of Man. |the case of Man. | + | | | + |(_a_) Therefore it is a |(_a_) Therefore it is | + |question of evidence |antecedently impossible | + |whether the Lamarckian |that the Lamarckian factors | + |factors have co-operated. |can have co-operated. | + | | | + |(_b_) Neither all species, |(_b_) Not only all species, | + |nor, _a fortiori_, all |but all specific | + |specific characters, have |characters, must | + |been due to natural |necessarily have been due | + |selection. |to natural selection. | + | | | + |(_c_) Thus the principle of |(_c_) Thus the principle of | + |Utility is not of universal |Utility must necessarily be | + |application, even where |of universal application, | + |species are concerned. |where species are | + | |concerned. | + | | | + |(_d_) Thus, also, the |(_d_) Thus, also, the | + |suggestion as to Sexual |suggestion as to Sexual | + |Selection, or any other |Selection, or of any other | + |supplementary cause of |supplementary cause of | + |modification, may be |modification, must be ruled | + |entertained; and, as in the |out; and, as in the case of | + |case of the Lamarckian |the Lamarckian factors, | + |factors, it is a question |their co-operation deemed | + |of evidence whether, or how |impossible. | + |far, they have co-operated. | | + | | | + |(_e_) No detriment arises |(_e_) The possibility--and, | + |to the theory of natural |_a fortiori_ the | + |selection as a theory of |probability--of any | + |the origin of species by |supplementary factors | + |entertaining the |cannot be entertained | + |possibility, or the |without serious detriment | + |probability, of |to the theory of natural | + |supplementary factors. |selection, as a theory of | + | |the origin of species. | + | | | + |(_f_) Cross-sterility in |(_f_) Cross-sterility in | + |species cannot possibly be |species is probably due to | + |due to natural selection. |natural selection[8]. | + + [8] This, to the best of my judgement, is the fairest extract that I + can give of Mr. Wallace's most recently published opinions on + the points in question. [In particular as regards (_a_) see + _Darwinism_ pp. 435-6.] But with regard to some of them, his + expression of opinion is not always consistent, as we shall find + in detail later on. Besides, I am here taking Mr. Wallace as + representative of the Neo-Darwinian school, one or other + prominent member of which has given emphatic expression to each + of the above propositions. + +As it will be my endeavour in the ensuing chapters to consider the +rights and the wrongs of these antithetical propositions, I may reserve +further quotations from Darwin's works, which will show that the above +is a correct epitome of his views as contrasted with those of Wallace +and the Neo-Darwinian school of Weismann. But here, where the object is +merely a statement of Darwin's theory touching the points in which it +differs from those of Wallace and Weismann, it will be sufficient to set +forth these points of difference in another and somewhat fuller form. So +far then as we are at present concerned, the following are the matters +of doctrine which have been clearly, emphatically, repeatedly, and +uniformly expressed throughout the whole range of Darwin's writings. + +1. That natural selection has been the main means of modification. + +2. That, nevertheless, it has not been the only means; but has been +supplemented or assisted by the co-operation of other causes. + +3. That the most "important" of these other causes has been the +inheritance of functionally-produced modifications (use-inheritance); +but this only because the transmission of such modifications to progeny +must always have had immediate reference to _adaptive_ ends, as +distinguished from merely useless change. + +4. That there are sundry other causes which lead to merely useless +change--in particular, "the direct action of external conditions, and +variations which seem to us in our ignorance to arise spontaneously." + +5. Hence, that the "principle of utility," far from being of universal +occurrence in the sphere of animate nature, is only of what may be +termed highly general occurrence; and, therefore, that certain other +advocates of the theory of natural selection were mistaken in +representing the universality of this principle as following by way of +necessary consequence from that theory. + +6. Cross-sterility in species cannot possibly be due to natural +selection; but everywhere arises as a result of some physiological +change having exclusive reference to the sexual system--a change which +is probably everywhere due to the same cause, although what this cause +could be Darwin was confessedly unable to suggest. + +Such, then, was the theory of evolution as held by Darwin, so far as the +points at present before us are concerned. And, it may now be added, +that the longer he lived, and the more he pondered these points, the +less exclusive was the _rôle_ which he assigned to natural selection, +and the more importance did he attribute to the supplementary factors +above named. This admits of being easily demonstrated by comparing +successive editions of his works; a method adopted by Mr. Herbert +Spencer in his essay on the _Factors of Organic Evolution_. + +My object in thus clearly defining Darwin's attitude regarding these +sundry points is twofold. + +In the first place, with regard to merely historical accuracy, it +appears to me undesirable that naturalists should endeavour to hide +certain parts of Darwin's teaching, and give undue prominence to others. +In the second place, it appears to me still more undesirable that this +should be done--as it usually is done--for the purpose of making it +appear that Darwin's teaching did not really differ very much from that +of Wallace and Weismann on the important points in question. I myself +believe that Darwin's judgement with regard to all these points will +eventually prove more sound and accurate than that of any of the recent +would-be improvers upon his system; but even apart from this opinion of +my own it is undesirable that Darwin's views should be misrepresented, +whether the misrepresentation be due to any unfavourable bias against +one side of his teaching, or to sheer carelessness in the reading of his +books. Yet the new school of evolutionists, to which allusion has now so +frequently been made, speak of their own modifications of Darwin's +teaching as "pure Darwinism," in contradistinction to what they call +"Lamarckism." In other words, they represent the principles of +"Darwinism" as standing in some kind of opposition to those of +"Lamarckism": the Darwinian principle of natural selection, they think, +is in itself enough to account for all the facts of adaptation in +organic nature. Therefore they are eager to dispense with the Lamarckian +principle of the inherited effects of use and disuse, together with the +direct influence of external conditions of life, and all or any other +causes of modification which either have been, or in the future may +possibly be, suggested. Now, of course, there is no reason why any one +should not hold these or any other opinions to which his own +independent study of natural science may lead him; but it appears to me +that there is the very strongest reason why any one who deviates from +the carefully formed opinions of such a man as Darwin, should above all +things be careful to be absolutely fair in his representations of them; +he should be scrupulously jealous, so to speak, of not letting it appear +that he is unjustifiably throwing over his own opinions the authority of +Darwin's name. + +But in the present case, as we have seen, not only do the Neo-Darwinians +strain the teachings of Darwin; they positively reverse those +teachings--representing as anti-Darwinian the whole of one side of +Darwin's system, and calling those who continue to accept that system in +its entirety by the name "Lamarckians." I know it is sometimes said by +members of this school, that in his utilization of Lamarckian principles +as accessory to his own, Darwin was actuated by motives of "generosity." +But a more preposterous suggestion could not well be made. We may +fearlessly challenge any one who speaks or writes in such a way, to show +any other instance where Darwin's great generosity of disposition had +the effect of influencing by one hair's breadth his still greater +loyalty to truth. Moreover, and with special regard to this particular +case, I would point out that in no one of his many allusions to, and +often lengthy discussions of, these so-called Lamarckian principles, +does he ever once introduce the name of Lamarck; while, on the other +hand, in the only places where he does so--whether in his books or in +his now published letters--he does so in order to express an almost +contemptuous dissatisfaction, and a total absence of obligation. Hence, +having regard to the "generosity" with which he always acknowledged +obligations, there can be no reasonable doubt that Darwin was not in the +smallest degree influenced by the speculative writings of Lamarck; or +that, even if Lamarck had never lived, the _Origin of Species_ would +have differed in any single particular from the form in which it now +stands. Finally, it must not be forgotten that Darwin's acceptance of +the theory of use-inheritance was vitally essential to his theory of +Pangenesis--that "beloved child" over which he had "thought so much as +to have lost all power of judging it[9]." + + [9] _Life and Letters_, vol. iii. pp. 72 and 75. + +What has just been said touching the relations between Darwin's theory +and that of Lamarck, applies with equal force to the relations between +Darwin's theory and any other theory appertaining to evolution which has +already been, or may hereafter be propounded. Yet so greatly have some +of the Neo-Darwinians misunderstood the teachings of Darwin, that they +represent as "Darwinian heresy" any suggestions in the way of factors +"supplementary to," or "co-operative with" natural selection. Of course, +if these naturalists were to avow themselves followers of Wallace, +instead of followers of Darwin, they would be perfectly justified in +repudiating any such suggestions as, _ipso facto_ heretical. But, as we +have now seen, through all his life Darwin differed from Wallace with +regard to this very point; and therefore, unlike Wallace, he was always +ready to entertain "additional suggestions" regarding the causes of +organic evolution--several of which, indeed, he himself supplied. Hence +we arrive at this curious state of matters. Those biologists who of late +years have been led by Weismann to adopt the opinions of Wallace, +represent as anti-Darwinian the opinions of other biologists who still +adhere to the unadulterated doctrines of Darwin. Weismann's _Essays on +Heredity_ (which argue that natural selection is the only possible cause +of adaptive modification) and Wallace's work on _Darwinism_ (which in +all the respects where any charge of "heresy" is concerned directly +contradicts the doctrine of Darwin)--these are the writings which are +now habitually represented by the Neo-Darwinians as setting forth the +views of Darwin in their "pure" form. The result is that, both in +conversation and in the press, we habitually meet with complete +inversions of the truth, which show the state of confusion into which a +very simple matter has been wrought by the eagerness of certain +naturalists to identify the views of Darwin with those of Wallace and +Weismann. But we may easily escape this confusion, if we remember that +wherever in the writings of these naturalists there occur such phrases +as "pure Darwinism" we are to understand pure _Wallaceism_, or the pure +theory of natural selection to the exclusion of any supplementary +theory. Therefore it is that for the sake of clearness I coined, several +years ago, the terms "Neo-Darwinian" and "Ultra-Darwinian" whereby to +designate the school in question. + + * * * * * + +So much, then, for the Darwinism of Darwin, as contrasted with the +Darwinism of Wallace, or, what is the same thing, of the Neo-Darwinian +school of Weismann. Next we may turn, by way of antithesis, to the +so-called "Neo-Lamarckian" school of the United States. For, by a +curious irony of fate, while the Neo-Darwinian school is in Europe +seeking to out-Darwin Darwin by assigning an exclusive prerogative to +natural selection in both kingdoms of animate nature, the Neo-Lamarckian +school is in America endeavouring to reform Darwinism in precisely the +opposite direction--viz. by transferring the sovereignty from natural +selection to the principles of Lamarck. Without denying to natural +selection a more or less important part in the process of organic +evolution, members of this school believe that much greater importance +ought to be assigned to the inherited effects of use and disuse than was +assigned to these agencies by Darwin. Perhaps this noteworthy state of +affairs, within a decade of Darwin's death, may lead us to anticipate +that his judgement--standing, as it does, between these two +extremes--will eventually prove the most accurate of all, with respect +to the relative importance of these factors of evolution. But, be this +as it may, I must now offer a few remarks upon the present position of +the matter. + +In the first place, to any one who (with Darwin and against Weismann) +admits not only the abstract possibility, but an actual working, of the +Lamarckian factors, it becomes difficult to determine, even +approximately, the degrees of value which ought to be ascribed to them +and to natural selection respectively. For, since the results are in +both cases identical in kind (as, adaptive changes of organic types), +where both sets of causes are supposed to be in operation together, we +have no means of estimating the relative shares which they have had in +bringing about these results. Of course there are large numbers of cases +where it cannot possibly be supposed that the Lamarckian factors have +taken any part at all in producing the observed effects; and therefore +in such cases there is almost full agreement among evolutionists in +theoretically ascribing such effects to the exclusive agency of natural +selection. Of such, for instance, are the facts of protective colouring, +of mimicry, of the growth of parts which, although _useful_, are never +_active_ (e.g. shells of mollusks, hard coverings of seeds), and so on. +But in the majority of cases where adaptive structures are concerned, +there is no means of discriminating between the influences of the +Lamarckian and the Darwinian factors. Consequently, if by the +Neo-Lamarckian school we understand all those naturalists who assign any +higher importance to the Lamarckian factors than was assigned to them by +Darwin, we may observe that members of this school differ very greatly +among themselves as to the degree of importance that ought to be +assigned. On the one hand we have, in Europe, Giard, Perrier, and Eimer, +who stand nearer to Darwin than do a number of the American +representatives--of whom the most prominent are Cope, Osborn, Packard, +Hyatt, Brooks, Ryder, and Dall. The most extreme of these is Professor +Cope, whose collection of essays entitled _The Origin of the Fittest_, +as well as his more recent and elaborate monograph on _The Development +of the Hard Parts of the Mammalia_, represent what appears even to some +other members of his school an extravagant estimate of the importance +of Lamarckian principles. + +But the most novel, and in many respects the most remarkable school of +what may be termed Anti-selectionists is one which is now (1894) rapidly +increasing both in numbers and in weight, not only in the New World, but +also in Germany, and to a lesser extent, in Great Britain. + +This school, without being either Lamarckian or Darwinian (for its +individual members differ widely from one another in these respects) +maintains a principle which it deems of more importance than either +use-inheritance or natural selection. This principle it calls +Self-adaptation. It is chiefly botanists who constitute this school, and +its principal representatives, in regard to authority, are Sachs, +Pfeffer and Henslow. + +Apart from topics which are to be dealt with in subsequent chapters, the +only matters of much importance which have been raised in the +Post-Darwinian period are those presented by the theories of Geddes, +Cope, Hyatt, and others, and certain more or less novel ideas set forth +in Wallace's _Darwinism_. + +Mr. Geddes has propounded a new theory of the origin of species, which +in his judgement supersedes to a large extent the theory of natural +selection. He has also, in conjunction with Mr. Thomson, propounded a +theory of the origin of sex. For my own part, I cannot see that these +views embody any principles or suggestions of a sufficiently definite +kind to constitute them theories at all. In this respect the views of +Mr. Geddes resemble those of Professors Cope, Hyatt, and others, on what +they term "the law of acceleration and retardation." In all these +cases, so far as I can see, the so-called explanations are not in fact +any explanations; but either a mere re-statement of the facts, or else +an enunciation of more or less meaningless propositions. Thus, when it +is said that the evolution of any given type has been due to the +"acceleration of growth-force" with respect to some structures, and the +"retardation of growth-force" with respect to others, it appears evident +that we have not any real explanation in terms of causality; we have +only the form of an explanation in the terms of a proposition. All that +has been done is to express the fact of evolution in somewhat obscure +phraseology, since the very thing we want to know about this fact +is--What are the causes of it as a fact, or the reasons which have led +to the increase of some of the parts of any given type, and the +concomitant decrease of others? It is merely the facts themselves that +are again presented by saying that the development has been in the one +case accelerated, while in the other it has been retarded[10]. + + [10] Take, for example, the following, which is a fair epitome of + the whole:--"I believe that this is the simplest mode of + stating and explaining the law of variation; that some forms + acquire something which their parents did not possess; and that + those which acquire something additional have to pass through + more numerous stages than their ancestors; and those which lose + something pass through fewer stages than their ancestors; and + these processes are expressed by the terms 'acceleration' and + 'retardation'" (_Origin of the Fittest_, pp. 125, 226, and + 297). Even if this be "the simplest mode of _stating_ the law + of variation," it obviously does nothing in the way of + _explaining_ the law. + +So much for what may be termed this New World theory of the origin of +species: it is a mere re-statement of the facts. Mr. Geddes' theory, on +the other hand, although more than a mere re-statement of the facts, +appears to me too vague to be of any explanatory service. His view is +that organic evolution has everywhere depended upon an antagonism, +within the limits of the same organism, between the processes of +nutrition and those of reproduction. But although he is thus able +hypothetically to explain certain facts--such as the shortening of a +flower-spike into a composite flower--the suggestion is obviously +inadequate to meet, even hypothetically, most of the facts of organic +evolution, and especially the development of _adaptive_ structures. +Therefore, it seems to me, we may dismiss it even as regards the +comparatively few facts which it might conceivably explain--seeing that +these same facts may be equally well explained by the causes which are +already known to operate in other cases. For it is the business of +natural selection to ensure that there shall nowhere be any needless +expenditure of vital energy, and, consequently, that everywhere the +balance between nutrition and reproduction shall be most profitably +adjusted. + +Similarly with respect to the theory of the _Origin of Sex_, I am unable +to perceive even this much of scientific relevancy. As stated by its +authors the theory is, that the female is everywhere "anabolic," as +compared with the male, which is "katabolic." By anabolic is meant +comparative inactivity of protoplasmic change due to a nutritive winding +up of molecular constitution, while by katabolic is meant the opposite +condition of comparative activity due to a dynamic running down of +molecular constitution. How, then, can the _origin_ of sex be explained, +or the _causes_ which led to the differentiation of the sexes be shown +by saying that the one sex is anabolic and the other katabolic? In so +far as these verbal statements serve to express what is said to be a +general fact--namely, that the female sexual elements are less mobile +than the male--they merely serve to re-state this general fact in +terminology which, as the authors themselves observe, is "unquestionably +ugly." But in so far as any question of _origin_ or _causality_ is +concerned, it appears to me that there is absolutely no meaning in such +statements. They belong to the order of merely formal explanations, as +when it is said that the toxic qualities of morphia are due to this drug +possessing a soporific character. + +Much the same, in my opinion, has to be said of the Rev. G. Henslow's +theory of the origin of species by what he terms "self-adaptation." +Stated briefly his view is that there is no sufficient evidence of +natural selection as a _vera causa_, while there is very abundant +evidence of adjustments occurring without it, first in individual +organisms, and next, by inheritance of acquired characters, in species. +Now, much that he says in criticism of the selection theory is of +considerable interest as such; but when we pass from the critical to the +constructive portions of his books and papers, we again meet with the +want of clearness in thought between a statement of facts in terms of a +proposition, and an explanation of them in those of causality. Indeed, I +understand from private correspondence, that Mr. Henslow himself admits +the validity of this criticism; for in answer to my questions,--"How +does Self-adaptation work in each case, and why should protoplasm be +able to _adapt itself_ into the millions of diverse mechanisms in +nature?"--he writes. "Self-adaptation does not profess to be a _vera +causa_ at all; for the true causes of variation can only be found in the +answer to your [above] questions, and I must say at once, _these +questions cannot be answered_." That is, they cannot be answered on the +hypothesis of self-adaptation, which is therefore a statement of the +facts of adaptation as distinguished from an explanation of them. +Nevertheless, two things have here to be noted. In the first place, the +statement of facts which Mr. Henslow has collected is of considerable +theoretical importance as tending to show that there are probably causes +of an internal kind (i. e. other than natural selection) which have been +largely concerned in the adaptive modification of plants. And, in the +second place, it is not quite true that the theory of self-adaptation +is, as its author says in the sentences above quoted, a mere statement +of the facts of adaptation, without any attempt at explaining their +causes. For in his published words he does attempt to do so[11]. And, +although I think his attempt is a conspicuous failure, I ought in +fairness to give examples of it. His books are almost exclusively +concerned in an application of his theory to the mechanisms of flowers +for securing their own fertilization. These mechanisms he ascribes, in +the case of entomophylous flowers, to the "thrusts," "strains," and +other "irritations" supplied to the flowers by their insect visitors, +and consequent "reactions" of the vegetable "protoplasm." But no attempt +is made to show why these "reactions" should be of an _adaptive_ kind, +so as to build up the millions of diverse and often elaborate mechanisms +in question--including not only forms and movements, but also colours, +odours, and secretions. For my own part I confess that, even granting to +an ultra-Lamarckian extent the inheritance of acquired characters, I +could conceive of "self-adaptation" alone producing all such innumerable +and diversified adjustments only after seeing, with Cardinal Newman, an +angel in every flower. Yet Mr. Henslow somewhat vehemently repudiates +any association between his theory and that of teleology. + + [11] _Floral Structures_ (Internat. Sc. Ser. lxiv. 1888): _The + Making of Flowers_ (Romance of Science Ser. 1891); and Linn. + Soc. Papers 1893-4. + +On the whole, then, I regard all the works which are here classed +together (those by Cope, Geddes, and Henslow), as resembling one another +both in their merits and defects. Their common merits lie in their +erudition and much of their criticism, while their common defects +consist on the one hand in not sufficiently distinguishing between mere +statements and real explanations of facts, and, on the other, in not +perceiving that the theories severally suggested as substitutes for that +of natural selection, even if they be granted true, could be accepted +only as co-operative factors, and by no stretch of logic as substitutes. + + * * * * * + +Turning now to Mr. Wallace's work on _Darwinism_, we have to notice, in +the first place, that its doctrine differs from "Darwinism" in regard to +the important dogma which it is the leading purpose of that work to +sustain--namely, that "the law of utility" is, to all intents and +purposes, universal, with the result that natural selection is virtually +the only cause of organic evolution. I say "to all intents and +purposes," or "virtually," because Mr. Wallace does not expressly +maintain the abstract impossibility of laws and causes other than those +of utility and natural selection; indeed, at the end of his treatise, he +quotes with approval Darwin's judgement, that "natural selection has +been the most important, but not the exclusive means of modification." +Nevertheless, as he nowhere recognizes any other law or cause of +adaptive evolution[12], he practically concludes that, on inductive or +empirical grounds, there _is_ no such other law or cause to be +entertained--until we come to the particular case of the human mind. But +even in making this one particular exception--or in representing that +some other law than that of utility, and some other cause than that of +natural selection, must have been concerned in evolving the mind of +man--he is not approximating his system to that of Darwin. On the +contrary, he is but increasing the divergence, for, of course, it was +Darwin's view that no such exception could be legitimately drawn with +respect to this particular instance. And if, as I understand must be the +case, his expressed agreement with Darwin touching natural selection not +being the only cause of adaptive evolution has reference to this point, +the quotation is singularly inapt. + + [12] "The law of correlation," and the "laws of growth," he does + recognize; and shows that they furnish an explanation of the + origin of many characters, which cannot be brought under "the + law of utility." + +Looking, then, to these serious differences between his own doctrine of +evolution--both organic and mental--and that of Darwin, I cannot think +that Mr. Wallace has chosen a suitable title for his book; because, in +view of the points just mentioned, it is unquestionable that _Darwinism_ +differs more widely from the _Origin of Species_ than does the _Origin +of Species_ from the writings of the Neo-Lamarckians. But, passing over +this merely nominal matter, a few words ought to be added on the very +material question regarding the human mind. In subsequent chapters the +more general question, or that which relates to the range of utility and +natural selection elsewhere will be fully considered. + +Mr. Wallace says,-- + + "The immense interest that attaches to the origin of the human + race, and the amount of misconception which prevails regarding the + essential teachings of Darwin's theory on the question, as well as + regarding my own special views upon it, induce me to devote a final + chapter to its discussion." + +Now I am not aware that there is any misconception in any quarter as to +the essential teachings of Darwin's theory on this question. Surely it +is rather the case that there is a very general and very complete +understanding on this point, both by the friends and the foes of +Darwin's theory--so much so, indeed, that it is about the only point of +similar import in all Darwin's writings of which this can be said. Mr. +Wallace's "special views" on the other hand are, briefly stated, that +certain features, both of the morphology and the psychology of man, are +inexplicable by natural selection--or indeed by any other cause of the +kind ordinarily understood by the term natural: they can be explained +only by supposing "the intervention of some distinct individual +intelligence," which, however, need not necessarily be "one Supreme +Intelligence," but some other order of Personality standing anywhere in +"an infinite chasm between man and the Great Mind of the universe[13]." +Let us consider separately the corporeal and the mental peculiarities +which are given as justifying this important conclusion. + + [13] _Natural Selection and Tropical Nature_, p. 205; 1891. + +The bodily peculiarities are the feet, the hands, the brain, the voice, +and the naked skin. + +As regards the feet Mr. Wallace writes, "It is difficult to see why the +prehensile power [of the great toe] should have been taken away," +because, although "it may not be compatible with perfectly easy erect +locomotion," "how can we conceive that early man, _as an animal_, gained +anything by purely erect locomotion[14]?" But surely it is not difficult +to conceive this. In the proportion that our simian progenitors ceased +to be arboreal in their habits (and there may well have been very good +utilitarian reasons for such a change of habitat, analogous to those +which are known to have occurred in the phylogenesis of countless other +animals), it would clearly have been of advantage to them that their +already semi-erect attitude should have been rendered more and more +erect. To name one among several probabilities, the more erect the +attitude, and the more habitually it was assumed, the more would the +hands have been liberated for all the important purposes of +manipulation. The principle of the physiological division of labour +would thus have come more and more into play: natural selection would +therefore have rendered the upper extremities more and more suited to +the execution of these purposes, while at the same time it would have +more and more adapted the lower ones to discharging the sole function of +locomotion. For my own part, I cannot perceive any difficulty about +this: in fact, there is an admirable repetition of the process in the +ontogeny of our own children[15]. + + [14] _Ibid._ pp. 197-8. + + [15] For an excellent discussion on the ontogeny of the child in + this connexion, see _Some Laws of Heredity_, by Mr. S. S. + Buckman, pp. 290, _et seq._ (Proc. Cotteswold Nat. Field Club, + vol. x. p. 3, 1892). + +Next, with regard to the hand, Mr. Wallace says, that it "contains +latent capacities which are unused by savages, and must have been even +less used by palaeolithic man and his still ruder predecessors." Thus, +"it has all the appearance of an organ prepared for the use of civilized +man[16]." Even if this be true, however, it would surely be a dangerous +argument to rely upon, seeing that we cannot say of how much importance +it may have been for early man--or even apes--to have had their power of +manipulation progressively improved. But is the statement true? It +appears to me that if Mr. Wallace had endeavoured to imitate the +manufactures that were practised by "palaeolithic man," he would have +found the very best of reasons for cancelling his statement. For it is +an extremely difficult thing to chip a flint into the form of an +arrow-head: when made, the suitable attachment of it to a previously +prepared arrow is no easy matter: neither a bow nor a bow-string could +have been constructed by hands of much less perfection than our own: and +the slaying of game with the whole apparatus, when it has been +constructed, requires a manual dexterity which we may be perfectly +certain that Mr. Wallace--unless he has practised the art from +boyhood--does not possess. + + [16] _loc. cit._ p. 198. + +So it is with his similar argument that the human voice is more +"powerful," more "flexible," and presents a greater "range" and +"sweetness" than the needs of savage life can be held to require. The +futility of this argument is self-evident as regards "power." And +although its weakness is not so obvious with respect to the other three +qualities which are named, need we go further than the closely analogous +case of certain birds to show the precariousness of arguing from such +facts of organic nature to the special operation of "a superior +intelligence"? I can hardly suppose that Mr. Wallace will invoke any +such agency for the purpose of explaining the "latent capacities" of the +voice of a parrot. Yet, in many respects, these are even more wonderful +than those of the human voice, albeit in a wild state they are "never +required or used[17]." + + [17] For a discussion of this remarkable case, see _Mental Evolution + in Animals_, pp. 222-3. It appears to me that if Mr. Wallace's + argument from the "latent capacities of the voice of Man" is + good for anything, _a fortiori_ it must be taken to prove that, + in the case of the Parrot, "the organ has been prepared in + anticipation" of the amusement which the cultivation of its + latent capacities arouses in "civilized man." + +Once more, with regard to the naked skin, it seems sufficient to quote +the following passage from the first edition of the _Descent of Man_. + + "The Rev. T. R. Stebbing, in commenting on this view, remarks, that + had Mr. Wallace 'employed his usual ingenuity on the question of + man's hairless skin, he might have seen the possibility of its + selection through its superior beauty, or the health attaching to + superior cleanliness. At any rate it is surprising that he should + picture to himself a superior intelligence plucking the hair from + the backs of savage men (to whom, according to his own account, it + would have been useful and beneficial), in order that the + descendants of the poor shorn wretches might, after many deaths + from cold and damp in the course of many generations,' have been + forced to raise themselves in the scale of civilization through the + practice of various arts, in the manner indicated by Mr. + Wallace[18]." + + [18] _Descent of Man_, 1st Ed. ch. xx. (Trans. Dev. Assoc. for + Science, 1890). + +To this it may be added that the Chimpanzee "Sally" was largely denuded +of hair, especially on the back, or the part of "man's organization" on +which Mr. Wallace lays special stress, as being in this respect out of +analogy with other mammalia[19]. + + [19] The late Prof. Moseley informed me that, during his voyage on + the _Challenger_, he had seen many men whose backs were well + covered with hair.--For an excellent discussion of the whole + question, chiefly in the light of embryology, see the paper by + Buckman already alluded to, pp. 280-289. Also, for an account + of an extraordinary hairy race of men, see _Alone with the + Hairy Ainu_, by A. H. Savage Landor, 1893. + +Lastly, touching his statement that the brain of savage man is both +quantitatively and qualitatively in advance of his requirements, it is +here also sufficient to refer to Darwin's answer, as given in the +_Descent of Man_. Mr. Wallace, indeed, ignores this answer in his recent +re-publication of the argument; but it is impossible to understand why +he should have done so. To me, at all events, it seems that one out of +several considerations which Darwin advances is alone sufficient to show +the futility of this argument. I allude to the consideration that the +power of forming abstract ideas with the complex machinery of language +as the vehicle of their expression, is probably of itself enough to +account for both the mass and the structure of a savage's brain. But +this leads us to the second division of Mr. Wallace's argument, or that +derived from the mental endowments of mankind. + +Here the peculiarities called into evidence are, "the Mathematical +Faculty," "the Artistic Faculties," and "the Moral Sense." With regard +to the latter, he avows himself a member of the intuitional school of +ethics; but does not prove a very powerful advocate as against the +utilitarian[20]. + + [20] E.g. "The special faculties we have been discussing clearly + point to the existence in man of something which he has not + derived from his animal progenitors--something which we may + best refer to as being of a spiritual essence or nature, + capable of progressive development under favourable conditions. + On the hypothesis of this spiritual nature, superadded to the + animal nature of man, we are able to understand much that is + otherwise mysterious or unintelligible in regard to him, + especially the enormous influence of ideas, principles, and + beliefs over his whole life and action. Thus alone can we + understand the constancy of the martyr, the unselfishness of + the philanthropist, the devotion of the patriot, the enthusiasm + of the artist, and the resolute and persevering search of the + scientific worker after nature's secrets. Thus we may perceive + that the love of truth, the delight in beauty, the passion for + justice, and the thrill of exultation with which we hear of any + act of courageous self-sacrifice, are the workings within us of + a higher nature which has not been developed by means of the + struggle for material existence." (_Darwinism_, p. 474.) I have + quoted this whole paragraph, because it is so inconsistent with + the rest of Mr. Wallace's system that a mere epitome of it + might well have been suspected of error. Given an intellectual + being, howsoever produced, and what is there "mysterious or + unintelligible" in "the enormous influence of ideas, + principles, and beliefs over his whole life and action"? Or + again, if he be also a social being, what is the relevancy of + adducing "the constancy of the martyr," "the unselfishness of + the philanthropist," "the devotion of the patriot," "the love + of truth," "the passion for justice," "the thrill of exultation + when we hear of any act of courageous self-sacrifice," in + evidence _against_ the law of _utility_, or in order to prove + that a "nature" thus endowed has "_not_ been developed by means + of the struggle for existence," when once this struggle has + been transferred from individuals to communities? The whole + passage reads like an ironical satire in favour of "Darwinism," + rather than a serious argument against it. + +It comes, then, to this. According to Mr. Wallace's eventual +conclusion, man is to be separated from the rest of organic nature, and +the steady progress of evolution by natural causes is to be regarded as +stopped at its final stage, because the human mind presents the +faculties of mathematical calculation and aesthetic perception. Surely, +on antecedent grounds alone, it must be apparent that there is here no +kind of proportion between the conclusion and the _data_ from which it +is drawn. That we are not confined to any such grounds, I will now try +to show. + +Let it be remembered, however, that in the following brief criticism I +am not concerned with the issue as to whether, or how far, the +"faculties" in question have owed their origin or their development to +_natural selection_. I am concerned only with the doctrine that in order +to account for such and such particular "faculty" of the human mind, +some order of causation must be supposed other than what we call +natural. I am not a Neo-Darwinist, and so have no desire to make +"natural selection" synonymous with "natural causation" throughout the +whole domain of life and of mind. And I quite agree with Mr. Wallace +that, at any rate, the "aesthetic faculty" cannot conceivably have been +produced by natural selection--seeing that it is of no conceivable +life-serving value in any of the stages of its growth. Moreover, it +appears to me that the same thing has to be said of the play instincts, +sense of the ludicrous, and sundry other "faculties" of mind among the +lower animals. It being thus understood that I am not differing from Mr. +Wallace where he imposes "limits" on the powers of natural selection, +but only where he seems to take for granted that this is the same thing +as imposing limits on the powers of natural causation, my criticism is +as follows. + +In the first place, it is a psychological fallacy to regard the +so-called "faculties" of mind as analogous to "organs" of the body. To +classify the latter with reference to the functions which they severally +perform is to follow a natural method of classification. But it is an +artificial method which seeks to partition mental _faculty_ into this, +that, and the other mental _faculties_. Like all other purely artificial +classifications, this one has its practical uses; but, also like them, +it is destitute of philosophical meaning. This statement is so well +recognized by psychologists, that there is no occasion to justify it. +But I must remark that any cogency which Mr. Wallace's argument may +appear to present, arises from his not having recognized the fact which +the statement conveys. For, had he considered the mind as a whole, +instead of having contemplated it under the artificial categories of +constituent "faculties," he would probably not have laid any such +special stress upon some of the latter. In other words, he would have +seen that the general development of the human mind as a whole has +presumably involved the growth of those conventionally abstracted parts, +which he regards as really separate endowments. Or, if he should find it +easier to retain the terms of his metaphor, we may answer him by saying +that the "faculties" of mind are "correlated," like "organs" of the +body; and, therefore, that any general development of the various other +"faculties" have presumably entailed a collateral development of the two +in question. + +Again, in the second place, it would seem that Mr. Wallace has not +sufficiently considered the co-operation of either well-known natural +causes, which must have materially assisted the survival of the fittest +where these two "faculties" are concerned. For, even if we disregard the +inherited effects of use--which, however, if entertained as possible in +any degree at all, must have here constituted an important +factor,--there remain on the one hand, the unquestionable influences of +individual education and, on the other hand, of the selection principle +operating in the mind itself. + +Taking these two points separately, it is surely sufficiently well known +that individual education--or special training, whether of mind or +body--usually raises congenital powers of any kind to a more or less +considerable level above those of the normal type. In other words, +whatever doubt there may be touching the _inherited_ effects of use, +there can be no question touching the immense _developmental_ effects +thereof in the individual life-time. Now, the conditions of savage life +are not such as lead to any deliberate cultivation of the "faculties" +either of the mathematical or aesthetic order. Consequently, as might be +expected, we find both of them in what Mr. Wallace regards as but a +"latent" stage of development. But in just the same way do we find that +the marvellous powers of an acrobat when specially trained from +childhood--say to curve his spine backwards until his teeth can bite his +heels--are "latent" in all men. Or, more correctly, they are _potential +in every child_. So it is with the prodigious muscular development of a +trained athlete, and with any number of other cases where either the +body or the mind is concerned. Why then should Mr. Wallace select the +particular instances of the mathematical and aesthetic powers in savages +as in any special sense "prophetic" of future development in trained +members of civilized races? Although it is true that these "latent +capacities and powers are unused by savages," is it not equally true +that savages fail to use their latent capacities and powers as tumblers +and athletes? Moreover, is it not likewise true that _as_ used by +savages, or as occurring normally in man, such capacities and powers are +no less poorly developed than are those of the "faculties" on which Mr. +Wallace lays so much stress? In other words, are not "latent capacities +and powers" of all kinds more or less equally in excess of anything that +is ever required of them by man in a state of nature? Therefore, if we +say that where mathematics and the fine arts are concerned the potential +capacities of savage man are in some mystical sense "prophetic" of a +Newton or a Beethoven, so in consistency ought we to say that in these +same capacities we discern a similar prophecy of those other uses of +civilized life which we have in a rope-dancer or a clown. + +Again, and in addition to this, it should be remembered that, even if we +do suppose any prophecy of this kind where the particular capacities in +question are concerned, we must clearly extend the reference to the +lower animals. Not a few birds display aesthetic feelings in a measure +fairly comparable with those of savages; while we know that some animals +present the germs of a "faculty" of computation[21]. But, it is +needless to add, this fact is fatal to Mr. Wallace's argument as I +understand it--viz. that the "faculties" in question have been in some +special manner communicated by some superior intelligence to _man_. + + [21] See _Proc. Zool. Soc._ June 4, 1889, for an account of the + performances in this respect of the Chimpanzee "Sally." Also, + for some remarks on the psychology of the subject, in _Mental + Evolution in Man_, p. 215. I should like to take this + opportunity of stating that, after the two publications above + referred to, this animal's instruction was continued, and that, + before her death, her "counting" extended as far as ten. That + is to say, any number of straws asked for from one to ten would + always be correctly given. + +Once more, it is obviously unfair to select such men as a "Newton, a La +Place, a Gauss, or a Cayley" for the purpose of estimating the +difference between savages and civilized man in regard to the latter +"faculty." These men are the picked mathematicians of centuries. +Therefore they are men who not only enjoyed all the highest possible +benefits of individual culture, but likewise those who have been most +endowed with mathematical power congenitally. So to speak, they are the +best variations in this particular direction which our race is known to +have produced. But had such variations arisen among savages it is +sufficiently obvious that they could have come to nothing. Therefore, it +is the _normal average_ of "mathematical faculty" in civilized man that +should be contrasted with that of savage man; and, when due regard is +paid to the all-important consideration which immediately follows, I +cannot feel that the contrast presents any difficulty to the theory of +human evolution by natural causation. + +Lastly, the consideration just alluded to is, that civilized man enjoys +an advantage over savage man far in advance even of those which arise +from a settled state of society, incentives to intellectual training, +and so on. This inestimable advantage consists in the art of writing, +_and the consequent transmission of the effects of culture from +generation to generation_. Quite apart from any question as to the +hereditary transmission of acquired characters, we have in this +_intellectual_ transmission of acquired _experience_ a means of +accumulative cultivation quite beyond our powers to estimate. For, +unlike all other cases where we recognize the great influence of +individual use or practice in augmenting congenital "faculties" (such as +in the athlete, pianist, &c.), in this case the effects of special +cultivation do not end with the individual life, but are carried on and +on through successive generations _ad infinitum_. Hence, a civilized man +inherits mentally, if not physically, the effects of culture for ages +past, and this in whatever direction he may choose to profit therefrom. +Moreover--and I deem this an immensely important addition--in this +unique department of purely intellectual transmission, a kind of +non-physical natural selection is perpetually engaged in producing the +best results. For here a struggle for existence is constantly taking +place among "ideas," "methods," and so forth, in what may be termed a +psychological environment. The less fit are superseded by the more fit, +and this not only in the mind of the individual, but, through language +and literature, still more in the mind of the race. "A Newton, a La +Place, a Gauss, or a Cayley," would all alike have been impossible, but +for a previously prolonged course of mental evolution due to the +selection principle operating in the region of mathematics, by means of +continuous survivals of the best products in successive generations. +And, of course, the same remark applies to art in all its branches[22]. + + [22] In Prof. Lloyd Morgan's _Animal Life and Intelligence_ there is + an admirable discussion on this subject, which has been + published since the above was written. The same has to be said + of Weismann's Essay on Music, where much that I have here said + is anticipated. With the views and arguments which Mr. Mivart + has forcibly set forth I have already dealt to the best of my + ability in a work on _Mental Evolution in Man_. + +Quitting then the last, and in my opinion the weakest chapter of +_Darwinism_, the most important points presented by other portions of +this work are--to quote its author's own enumeration of them--an +attempted "proof that all specific characters are (or once have been) +either useful in themselves or correlated with useful characters": an +attempted "proof that natural selection can, in certain cases, increase +the sterility of crosses": an attempted "proof that the effects of use +and disuse, even if inherited, must be overpowered by natural +selection": an attempted proof that the facts of variation in nature are +in themselves sufficient to meet the difficulty which arises against the +theory of natural selection, as held by him, from the swamping effects +of free intercrossing: and, lastly, "a fuller discussion on the colour +relations of animals, with additional facts and arguments on the origin +of sexual differences of colour." As I intend to deal with all these +points hereafter, excepting the last, it will be sufficient in this +opening chapter to remark, that in as far as I disagree with Mr. Wallace +(and agree with Darwin), on the subject of "sexual differences of +colour," my reasons for doing so have been already sufficiently stated +in Part I. But there is much else in his treatment of this subject which +appears to me highly valuable, and therefore presenting an admirable +contribution to the literature of Darwinism. In particular, it appears +to me that the most important of his views in this connexion probably +represents the truth--namely, that, among the higher animals, more or +less conspicuous peculiarities of colour have often been acquired for +the purpose of enabling members of the same species quickly and +certainly to recognize one another. This theory was first published by +Mr. J. E. Todd, in 1888, and therefore but a short time before its +re-publication by Mr. Wallace. As his part in the matter has not been +sufficiently recognized, I should like to conclude this introductory +chapter by drawing prominent attention to the merits of Mr. Todd's +paper. For not only has it the merit of priority, but it deals with the +whole subject of "recognition colours"--or, as he calls them, "directive +colours"--in a more comprehensive manner than has been done by any of +his successors. In particular, he shows that the principle of +recognition-marking is not restricted to facilitating sexual +intercourse, but extends also to several other matters of importance in +the economy of animal life[23]. + + [23] _American Naturalist_, xxii. pp. 201-207. + + * * * * * + +Having thus briefly sketched the doctrines of the sundry Post-Darwinian +Schools from a general point of view, I shall endeavour throughout the +rest of this treatise to discuss in appropriate detail the questions +which have more specially come to the front in the post-Darwinian +period. It can scarcely be said that any one of these questions has +arisen altogether _de novo_ during this period; for glimmerings, more or +less conspicuous, of all are to be met with in the writings of Darwin +himself. Nevertheless it is no less true that only after his death have +they been lighted up to the full blaze of active discussion[24]. By far +the most important of them are those to which the rest of this treatise +will be confined. They are four in number, and it is noteworthy that +they are all intimately connected with the great question which Darwin +spent the best years of his life in contemplating, and which has +therefore, in one form or another, occupied the whole of the present +chapter--the question as to whether natural selection has been the sole +cause, or but the chief cause of modification. + + [24] It is almost needless to say that besides the works mentioned + in this chapter, many others have been added to the literature + of Darwinism since Darwin's death. But as none of these profess + to contain much that is original, I have not thought it + necessary to consider any of them in this merely general review + of the period in question. In subsequent chapters, however, + allusions will be made to those among them which I deem of most + importance. + + [Since this note was written and printed the following works + have been published to which it does not apply: _Animal Life + and Intelligence_, by Professor Lloyd Morgan; _The Colours of + Animals_, by Professor Poulton; and _Materials for the Study of + Variation_, by Mr. Bateson. All these works are of high value + and importance. Special reference should also be made to + Professor Weismann's Essays.] + +The four questions above alluded to appertain respectively to Heredity, +Utility, Isolation, and Physiological Selection. Of these the first two +will form the subject-matter of the present volume, while the last two +will be dealt with in the final instalment of _Darwin, and after +Darwin_. + + + + +SECTION I + +_HEREDITY_ + + + + +CHAPTER II. + +CHARACTERS AS HEREDITARY AND ACQUIRED (PRELIMINARY). + + +We will proceed to consider, throughout Section I of the present work, +the most important among those sundry questions which have come to the +front since the death of Darwin. For it was in the year after this event +that Weismann published the first of his numerous essays on the subject +of Heredity, and, unquestionably, it has been these essays which have +given such prominence to this subject during the last decade. + +At the outset it is desirable to be clear upon certain points touching +the history of the subject; the limits within which our discussion is to +be confined; the relation in which the present essay stands to the one +that I published last year under the title _An Examination of +Weismannism_; and several other matters of a preliminary kind. + +The problems presented by the phenomena of heredity are manifold; but +chief among them is the hitherto unanswered question as to the +transmission or non-transmission of acquired characters. This is the +question to which the present Section will be confined. + +Although it is usually supposed that this question was first raised by +Weismann, such was not the case. Any attentive reader of the successive +editions of Darwin's works may perceive that at least from the year 1859 +he had the question clearly before his mind; and that during the rest of +his life his opinion with regard to it underwent considerable +modifications--becoming more and more Lamarckian the longer that he +pondered it. But it was not till 1875 that the question was clearly +presented to the general public by the independent thought of Mr. +Galton, who was led to challenge the Lamarckian factors _in toto_ by way +of deduction from his theory of Stirp--the close resemblance of which to +Professor Weismann's theory of Germ-plasm has been shown in my +_Examination of Weismannism_. Lastly, I was myself led to doubt the +Lamarckian factors still further back in the seventies, by having found +a reason for questioning the main evidence which Mr. Darwin had adduced +in their favour. This doubt was greatly strengthened on reading, in the +following year, Mr. Galton's _Theory of Heredity_ just alluded to; and +thereupon I commenced a prolonged course of experiments upon the +subject, the general nature of which will be stated in future chapters. +Presumably many other persons must have entertained similar misgivings +touching the inheritance of acquired characters long before the +publication of Weismann's first essay upon the subject in 1883. The +question as to the inheritance of acquired characters was therefore +certainly not first raised by Weismann--although, of course, there is no +doubt that it was conceived by him independently, and that he had the +great merit of calling general attention to its existence and +importance. On the other hand, it cannot be said that he has succeeded +in doing very much towards its solution. It is for these reasons that +any attempt at dealing with Weismann's fundamental postulate--i.e. that +of the non-inheritance of acquired characters--was excluded from my +_Examination of Weismannism_. As there stated, he is justified in +assuming, for the purposes of his discussion, a negative answer to the +question of such inheritance; but evidently the question itself ought +not to be included within what we may properly understand by +"Weismannism." Weismannism, properly so called, is an elaborate system +of theories based on the fundamental postulate just mentioned--theories +having reference to the mechanism of heredity on the one hand, and to +the course of organic evolution on the other. Now it was the object of +the foregoing _Examination_ to deal with this system of theories _per +se_; and therefore we have here to take a new point of departure and to +consider separately the question of fact as to the inheritance or +non-inheritance of acquired characters. At first sight, no doubt, it +will appear that in adopting this method I am putting the cart before +the horse. For it may well appear that I ought first to have dealt with +the validity of Weismann's postulate, and not till then to have +considered the system of theories which he has raised upon it. But this +criticism is not likely to be urged by any one who is well acquainted +with the questions at issue. For, in the first place, it is notorious +that the question of fact is still open to question; and therefore it +ought to be considered separately, or apart from any theories which may +have been formed with regard to it. In the second place, our judgement +upon this question of fact must be largely influenced by the validity of +general reasonings, such as those put forward in the interests of rival +theories of heredity; and, as the theory of germ-plasm has been so +thoughtfully elaborated by Professor Weismann, I have sought to give it +the attention which it deserves as preliminary to our discussion of the +question of fact which now lies before us. Thirdly and lastly, even if +this question could be definitely answered by proving either that +acquired characters are inherited or that they are not, it would by no +means follow that Weismann's theory of heredity would be proved wholly +false in the one case, or wholly true in the other. That it need not be +wholly true, even were its fundamental postulate to be proved so, is +evident, because, although the fact might be taken to prove the theory +of Continuity, the theory of Germ-plasm is, as above stated, very much +more than this. That the theory of Germ-plasm need not be wholly false, +even if acquired characters should ever be proved heritable, a little +thought may easily show, because, in this event, the further question +would immediately arise as to the degrees and the comparative frequency +of such inheritance. For my own part, as stated in the _Examination_, I +have always been disposed to accept Mr. Galton's theory of Stirp in +preference to that of Germ-plasm on this very ground--i. e. that it does +not dogmatically exclude the possibility of an occasional inheritance of +acquired characters in faint though cumulative degrees. And whatever our +individual opinions may be touching the admissibility of such a _via +media_ between the theories of Pangenesis and Germ-plasm, at least we +may all agree on the desirability of fully considering the matter as a +preliminary to the discussion of the question of fact. + +As it is not to be expected that even those who may have read my +previous essay can now carry all these points in their memories, I will +here re-state them in a somewhat fuller form. + +The following diagram will serve to give a clearer view of the sundry +parts of Professor Weismann's system of theories, as well as of their +relations to one another. + +[Illustration: Postulate as to the absolute non-inheritance of acquired +characters.] + +Now, as just explained, the parts of this system which may be properly +and distinctively called "Weismannism" are those which go to form the +Y-like structure of deductions from the fundamental postulate. +Therefore, it was the Y-like system of deductions which were dealt with +in the _Examination of Weismannism_, while it is only his basal +postulate which has to be dealt with in the following chapters. + +So much, then, for the relations of Weismann's system of theories to one +another. It is, however, of even more importance that we should gain a +clear view of the relations between his theory of _heredity_ to those of +Darwin and of Galton, as preliminary to considering the fundamental +question of fact. + +As we have already seen, the theory of germ-plasm is not only a theory +of heredity: it is also, and more distinctively, a theory of evolution, +&c. As a theory of heredity it is grounded on its author's fundamental +postulate--the _continuity_ of germ-plasm. But as a theory of evolution, +it requires for its support this additional postulate, that the +continuity of germ-plasm has been _absolute_ "since the first origin of +life." It is clear that this additional postulate is not needed for his +theory of heredity, but only for his additional theory of evolution, &c. +There have been one or two other theories of heredity, prior to this +one, which, like it, have been founded on the postulate of Continuity of +the substance of heredity; but it has not been needful for any of these +theories to postulate further that this substance has been _always_ thus +isolated, or even that it is now _invariably_ so. For even though the +isolation be frequently invaded by influences of body-changes on the +congenital characters of this substance, it does not follow that this +principle of Continuity may not still be true _in the main_, even +although it is supplemented in some degree by that of use-inheritance. +Indeed, so far as the phenomena of heredity are concerned, it is +conceivable that all congenital characters were originally acquired, +and afterwards became congenital on account of their long inheritance. I +do not myself advocate this view as biologically probable, but merely +state it as logically possible, and in order to show that, so far as the +phenomena of heredity are concerned, there appears to be no reason for +Weismann's deduction that the principle of Continuity, if true at all, +must be _absolute_. And it would further appear, the only reason why he +makes this deduction (stem of the Y) is in order to provide a foundation +for his further theories of evolution, &c. (arms of the Y). It is indeed +necessary for these further theories that body-changes should never +exercise any hereditary influence on the hereditary endowments of +germ-plasm, and therefore it is that he posits the substance of heredity +as, not only continuous, but uninterruptably so "since the first origin +of life." + +Now, this may be made more clear by briefly comparing Weismann's theory +with those of Darwin and of Galton. Weismann's theory of heredity, then, +agrees with its predecessors which we are considering in all the +following respects. The substance of heredity is particulate; is mainly +lodged in highly specialized cells; is nevertheless also distributed +throughout the general cellular tissues, where it is concerned in all +processes of regeneration, repair, and a-sexual reproduction; presents +an enormously complex structure, in that every constituent part of a +potentially future organism is represented in a fertilized ovum by +corresponding particles; is everywhere capable of virtually unlimited +multiplication, without ever losing its hereditary endowments; is often +capable of carrying these endowments in a dormant state through a long +series of generations until at last they reappear in what we recognize +as recursions. Thus far all three theories are in agreement. In fact, +the only matter of any great importance wherein they disagree has +reference to the doctrine of Continuity[25]. For while Darwin's theory +supposes the substance of heredity to be mainly formed anew in each +ontogeny, and therefore that the continuity of this substance is for the +most part interrupted in every generation[26], Weismann's theory +supposes this substance to be formed only during the phylogeny of each +species, and therefore to have been absolutely uninterrupted since the +first origin of life. + + [25] Originally, Weismann's further assumption as to the perpetual + stability of germ-plasm, "since the first origin of sexual + reproduction," was another very important point of difference, + but this has now been withdrawn. + + [26] I say "_mainly_ formed anew," and "_for the most part_ + interrupted," because even Darwin's theory does not, as is + generally supposed, exclude the doctrine of Continuity _in + toto_. + +But now, Galton's theory of heredity stands much nearer to Weismann's in +this matter of Continuity; for it is, as he says, a theory of "modified +pangenesis," and the modification consists in allowing very much more +for the principle of Continuity than is allowed by Darwin's theory; in +fact he expresses himself as quite willing to adopt (on adequate grounds +being shown) the doctrine of Continuity as absolute, and therefore +propounded, as logically possible, the identical theory which was +afterwards and independently announced by Weismann. Or, to quote his own +words-- + + "We might almost reserve our belief that the structural [i. e. + somatic] cells can react on the sexual elements at all, and we may + be confident that at most they do so in a very faint degree; in + other words, that acquired modifications are barely, if at all, + _inherited_, in the correct sense of that word[27]." + + [27] _Theory of Heredity_ (Journ. Anthrop. Inst. 1875, p. 346). + +So far Mr. Galton; but for Weismann's further theory of evolution, &c., +it is necessary to postulate the additional doctrine in question; and it +makes a literally immeasurable difference to any theory of evolution +whether or not we entertain this additional postulate. For no matter how +faintly or how fitfully the substance of heredity may be modified by +somatic tissues, the Lamarckian principles are hypothetically allowed +some degree of play. And although this is a lower degree than Darwin +supposed, their influence in determining the course of organic evolution +may still have been enormous; seeing that their action in any degree +must always have been _directive_ of variation on the one hand, and +_cumulative_ on the other. + +Thus, by merely laying this theory side by side with Weismann's we can +perceive at a glance how a _pure_ theory of _heredity_ admits of being +based on the postulate of Continuity alone, without cumbering itself by +any further postulate as to this Continuity being _absolute_. And this, +in my opinion is the truly scientific attitude of mind for us to adopt +as preliminary to the following investigation. For the whole +investigation will be concerned--and concerned only--with this question +of Continuity as absolute, or as admitting of degrees. There is, without +any question, abundant evidence to prove that the substance of heredity +is at least partly continuous (Gemmules). It may be that there is also +abundant evidence to prove this substance much more _largely_ +continuous than Darwin supposed (Stirp); but be this as it may, it is +certain that any such question as to the _degree_ of continuity differs, +_toto caelo_, from that as to whether there can ever be any continuity +at all. + +How, then, we may well ask, is it that so able a naturalist and so clear +a thinker as Weismann can have so far departed from the inductive +methods as to have not merely propounded the question touching +Continuity and its degrees, or even of Continuity as absolute; but to +have straightway assumed the latter possibility as a basis on which to +run a system of branching and ever-changing speculations concerning +evolution, variation, the ultimate structure of living material, the +intimate mechanism of heredity, or, in short, such a system of deductive +conjectures as has never been approached in the history of science? The +answer to this question is surely not far to seek. Must it not be the +answer already given? Must it not have been for the sake of rearing this +enormous structure of speculation that Weismann has adopted the +assumption of Continuity as absolute? As we have just seen, Galton had +well shown how a theory of heredity could be founded on the general +doctrine of Continuity, without anywhere departing from the inductive +methods--even while fully recognizing the possibility of such continuity +as absolute. But Galton's theory was a "_Theory of Heredity_," and +nothing more. Therefore, while clearly perceiving that the Continuity in +question _may_ be absolute, he saw no reason, either in fact or in +theory, for concluding that it _must_ be. On the contrary, he saw that +this question is, for the present, necessarily unripe for profitable +discussion--and, _a fortiori_, for the shedding of clouds of seed in all +the directions of "Weismannism." + +Hence, what I desire to be borne in mind throughout the following +discussion is, that it will have exclusive reference to the question of +fact already stated, without regard to any superjacent theories; and, +still more, that there is a vast distinction between any question +touching the degrees in which acquired characters are transmitted to +progeny, and the question as to whether they are ever transmitted in any +degree at all. Now, the latter question, being of much greater +importance than the former, is the one which will mainly occupy our +attention throughout the rest of this Section. + +We have already seen that before the subject was taken up by Weismann +the difference between acquired and congenital characters in respect to +transmissibility was generally taken to be one of degree; not one of +kind. It was usually supposed that acquired characters, although not so +fully and not so certainly inherited as congenital characters, +nevertheless were inherited in some lesser degree; so that if the same +acquired character continued to be successively acquired in a number of +sequent generations, what was at first only a slight tendency to be +inherited would become by summation a more and more pronounced tendency, +till eventually the acquired character might become as strongly +inherited as a congenital one. Or, more precisely, it was supposed that +an acquired character, in virtue of such a summation of hereditary +influence, would in time become congenital. Now, if this supposition be +true, it is evident that more or less assistance must be lent to +natural selection in its work of evolving adaptive modifications[28]. +And inasmuch as we know to what a wonderful extent adaptive +modifications are secured during individual life-times--by the direct +action of the environment on the one hand, and by increased or +diminished use of special organs and mental faculties on the other--it +becomes obvious of what importance even a small measure of +transmissibility on their part would be in furnishing to natural +selection ready-made variations in required directions, as distinguished +from promiscuous variations in all directions. Contrariwise, if +functionally-produced adaptations and adaptations produced by the direct +action of the environment are never transmitted in any degree, not only +would there be an incalculable waste, so to speak, of adaptive +modifications--these being all laboriously and often most delicately +built up during life-times of individuals only to be thrown down again +as regards the interest of species--but so large an additional burden +would be thrown upon the shoulders of natural selection that it becomes +difficult to conceive how even this gigantic principle could sustain it, +as I shall endeavour to show more fully in future chapters. On the other +hand, however, Weismann and his followers not only feel no difficulty in +throwing overboard all this ready-made machinery for turning out +adaptive modifications when and as required; but they even represent +that by so doing they are following the logical maxim, _Entia non sunt +multiplicanda praeter necessitatem_--which means, in its relation to +causality, that we must not needlessly multiply hypothetical principles +to explain given results. But when appeal is here made to this logical +principle--the so-called Law of Parsimony--two things are forgotten. + + [28] Mr. Platt Ball has, indeed, argued that "use-inheritance would + often be an evil," since, for example, "the condyle of the + human jaw would become larger than the body of the jaw, because + as the fulcrum of the lever it receives more pressure"; and + similarly as regards many other hypothetical cases which he + mentions. (_The Effects of Use and Disuse_, pp. 128-9 _et + seq._) But it is evident that this argument proves too much. + For if the effects of use and disuse as transmitted to progeny + would be an evil, it could only be because these effects as + they occur in the parents are an evil--and this they most + certainly are not, being, on the contrary and as a general + rule, of a high order of adaptive value. Moreover, in the race, + there is a superadded agency always at work, which must + effectually prevent any undue accumulation of these + effects--namely, natural selection, which every Darwinist + accepts as a controlling principle of all or any other + principles of change. Therefore, if, as first produced in the + life-time of individuals, the effects of use and disuse are not + injurious, much less can they become so if transmitted through + the life-time of species. Again, Mr. Wallace argues that, even + supposing use-inheritance to occur, its adapting work in the + individual can never extend to the race, seeing that the + natural selection of fortuitous variations in the directions + required must always produce the adaptations _more quickly_ + than would be possible by use-inheritance. This argument, being + one of more weight, will be dealt with in a future chapter. + +In the first place, it is forgotten that the very question in debate is +whether causes of the Lamarckian order _are_ unnecessary to explain all +the phenomena of organic nature. Of course if it could be proved that +the theory of natural selection alone is competent to explain all these +phenomena, appeal to the logical principle in question would be +justifiable. But this is precisely the point which the followers of +Darwin refuse to accept; and so long as it remains the very point at +issue, it is a mere begging the question to represent that a class of +causes which have hitherto been regarded as necessary are, in fact, +unnecessary. Or, in other words, when Darwin himself so decidedly held +that these causes are necessary as supplements to natural selection, the +burden of proof is quite as much on the side of Weismann and his +followers to show that Darwin's opinion was wrong, as it is on the side +of Darwin's followers to show that it was right. Yet, notwithstanding +the elaborate structure of theory which Weismann has raised, there is +nowhere one single fact or one single consideration of much importance +to the question in debate which was not perfectly well known to Darwin. +Therefore I say that all this challenging of Darwinists to justify their +"Lamarckian assumptions" really amounts to nothing more than a pitting +of opinion against opinion, where there is at least as much call for +justification on the one side as on the other. + +Again, when these challenges are thrown down by Weismann and his +followers, it appears to be forgotten that the conditions of their own +theory are such as to render acceptance of the gauge a matter of great +difficulty. The case is very much like that of a doughty knight pitching +his glove into the sea, and then defying any antagonist to take it up. +That this is the case a very little explanation will suffice to show. + +The question to be settled is whether acquired characters are ever +transmitted by heredity. Now suppose, for the sake of argument, that +acquired characters are transmitted by heredity--though not so fully and +not so certainly as congenital characters--how is this fact to be proved +to the satisfaction of Weismann and his followers? First of all they +answer,--Assuredly by adducing experimental proof of the inheritance of +injuries, or mutilations. But in making this answer they appear to +forget that Darwin has already shown its inefficiency. That the +self-styled Neo-Lamarckians have been much more unguarded in this +respect, I fully admit; but it is obviously unfair to identify Darwin's +views with those of a small section of evolutionists, who are really as +much opposed to Darwin's teaching on one side as is the school of +Weismann on the other. Yet, on reading the essays of Weismann +himself--and still more those of his followers--one would almost be led +to gather that it is claimed by him to have enunciated the distinction +between congenital and acquired characters in respect of +transmissibility; and therefore also to have first raised the objection +which lies against the theory of Pangenesis in respect of the +non-transmissibility of mutilations. In point of fact, however, Darwin +is as clear and decided on these points as Weismann. And his answer to +the obvious difficulty touching the non-transmissibility of mutilations +is, to quote his own words, "the long-continued inheritance of a part +which has been removed during many generations is no real anomaly, for +gemmules formerly derived from the part are multiplied and transmitted +from generation to generation[29]." Therefore, so far as Darwin's theory +is concerned, the challenge to produce evidence of the transmission of +injuries is irrelevant: it is no more a part of Darwin's theory than it +is of Weismann's to maintain that injuries _are_ transmitted. + + [29] _Variation under Domestication_, ii. 392. + +There is, however, one point in this connexion to which allusion must +here be made. Although Darwin did not believe in the transmissibility +of mutilations when these consist merely in the amputation of parts of +an organism, he did believe in a probable tendency to transmission when +removal of the part is followed by gangrene. For, as he says, in that +case, all the gemmules of the mutilated or amputated part, as they are +gradually attracted to that part (in accordance with the law of affinity +which the theory assumes), will be successively destroyed by the morbid +process. Now it is of importance to note that Darwin made this exception +to the general rule of the non-transmissibility of mutilations, not +because his theory of pangenesis required it, but because there appeared +to be certain very definite observations and experiments--which will be +mentioned later on--proving that when mutilations are followed by +gangrene they are apt to be inherited: his object, therefore, was to +reconcile these alleged facts with his theory, quite as much as to +sustain his theory by such facts. + +So much, then, for the challenge to produce direct evidence of the +transmissibility of acquired characters, so far as mutilations are +concerned: believers in Darwin's theory, as distinguished from +Weismann's, are under no obligation to take up such a challenge. But the +challenge does not end here. Show us, say the school of Weismann, a +single instance where an acquired character _of any kind_ (be it a +mutilation or otherwise) has been inherited: this is all that we +require: this is all that we wait for: and surely, unless it be +acknowledged that the Lamarckian doctrine reposes on mere assumption, at +least one such case ought to be forthcoming. Well, nothing can sound +more reasonable than this in the first instance; but as soon as we +begin to cast about for cases which will satisfy the Neo-Darwinians, we +find that the structure of their theory is such as to preclude, in +almost every conceivable instance, the possibility of meeting their +demand. For their theory begins by assuming that natural selection is +the one and only cause of organic evolution. Consequently, what their +demand amounts to is throwing upon the other side the burden of +disproving this assumption--or, in other words, of proving the negative +that in any given case of transmitted adaptation natural selection has +_not_ been the sole agent at work. Now, it must obviously be in almost +all cases impossible to prove this negative among species in a state of +nature. For, even supposing that among such species Lamarckian +principles have had a large share in the formation of hereditary and +adaptive characters, how would Weismann himself propose that we should +set about the proof of such a fact, where the proof demanded by his +assumption is, that the _abstract possibility_ of natural selection +having had anything to do with the matter must be excluded? Obviously +this is impossible in the case of inherited characters which are also +_adaptive_ characters. How then does it fare with the case of inherited +characters which are not also adaptive? Merely that this case is met by +another and sequent assumption, which constitutes an integral part of +the Neo-Darwinian creed--namely, that in nature there _can be no such +characters_. Seeing that natural selection is taken to be the only +possible cause of change in species, it follows that all changes +occurring in species must necessarily be adaptive, whether or not we are +able to perceive the adaptations. In this way apparently useless +characters, as well as obviously useful ones, are ruled out of the +question: that is to say, _all_ hereditary characters of species in a +state of nature are _assumed_ to be due to natural selection, and then +it is demanded that the validity of this assumption should be disproved +by anybody who doubts it. Yet Weismann himself would be unable to +suggest any conceivable method by which it can be disproved among +species in a state of nature--and this even supposing that the +assumption is entirely false[30]. + + [30] In subsequent chapters, especially devoted to the question + (i.e. Section II), the validity of this assumption will be + considered on its own merits. + +Consequently, the only way in which these speciously-sounding challenges +can be adequately met is by removing some individuals of a species from +a state of nature, and so from all known influences of natural +selection; then, while carefully avoiding artificial selection, causing +these individuals and their progeny through many generations unduly to +exercise some parts of their bodies, or unduly to fail in the exercise +of others. But, clearly, such an experiment is one that must take years +to perform, and therefore it is now too early in the day to reproach the +followers of Darwin with not having met the challenges which are thrown +down by the followers of Weismann[31]. + + [31] I say "the followers of Weismann," because Weismann himself, + with his clear perception of the requirements of experimental + research, expressly states the above considerations, with the + conclusions to which they lead. Nevertheless, he is not + consistent in his utterances upon this matter; for he + frequently expresses himself to the effect, "that the _onus + probandi_ rests with my opponents, and therefore they ought to + bring forward actual proofs" (_Essays_, i. p. 390). But, as + above shown, the _onus_ rests as much with him as with his + opponents; while, even if his opponents are right, he elsewhere + recognizes that they can bring "actual proofs" of the fact only + as a result of experiments which must take many years to + perform. + +Probably enough has now been said to show that the Neo-Darwinian +assumption precludes the possibility of its own disproof from any of the +facts of nature (as distinguished from domestication)--and this even +supposing that the assumption be false. On the other hand, of course, it +equally precludes the possibility of its own proof; and therefore it is +as idle in Darwinists to challenge Weismann for proof of his negative +(i. e. that acquired characters are not transmitted), as it is in +Weismann to challenge Darwinists for proof of the opposite negative (i. +e. that all seeming cases of such transmission are not due to natural +selection). This dead-lock arises from the fact that in nature it is +beyond the power of the followers of Darwin to exclude the abstract +possibility of natural selection in any given case, while it is equally +beyond the power of the followers of Weismann to exclude the abstract +possibility of Lamarckian principles. Therefore at present the question +must remain for the most part a matter of opinion, based upon general +reasoning as distinguished from special facts or crucial experiments. +The evidence available on either side is presumptive, not +demonstrative[32]. But it is to be hoped that in the future, when time +shall have been allowed for the performance of definite experiments on a +number of generations of domesticated plants or animals, intentionally +shielded from the influences of natural selection while exposed to those +of the Lamarckian principles, results will be gained which will finally +settle the question one way or the other. + + [32] Note A. + +Meanwhile, however, we must be content with the evidence as it stands; +and this will lead us to the second division of our subject. That is to +say, having now dealt with the antecedent, or merely logical, state of +the question, we have next to consider what actual, or biological, +evidence there is at present available on either side of it. Thus far, +neither side in the debate has any advantage over the other. On grounds +of general reasoning alone they both have to rely on more or less +dogmatic assumptions. For it is equally an unreasoned statement of +opinion whether we allege that all the phenomena of organic evolution +can be, or can not be, explained by the theory of natural selection +alone. We are at present much too ignorant touching the causes of +organic evolution to indulge in dogmatism of this kind; and if the +question is to be referred for its answer to authority, it would appear +that, both in respect of number and weight, opinions on the side of +having provisionally to retain the Lamarckian factors are more +authoritative than those _per contra_[33]. + + [33] For a fair and careful statement of the present balance of + authoritative opinion upon the question, see H. F. Osborn, + _American Naturalist_, 1892, pp. 537-67. + + * * * * * + +Turning then to the question of fact, with which the following chapters +are concerned, I will conclude this preliminary one with a few words on +the method of discussion to be adopted. + +First I will give the evidence in favour of Lamarckianism; this will +occupy the next two chapters. Then, in Chapter V, I will similarly give +the evidence _per contra_, or in favour of Continuity as absolute. +Lastly, I will sum up the evidence on both sides, and give my own +judgement on the whole case. But on whichever side I am thus acting as +special pleader for the time being, I will adduce only such arguments as +seem to me valid--excluding alike from both the many irrelevant or +otherwise invalid reasonings which have been but too abundantly +published. Moreover, I think it will be convenient to consider all that +has been said--or may be said--in the way of criticism to each argument +by the opposite side while such argument is under discussion--i. e. not +to wait till all the special pleading on one side shall have been +exhausted before considering the exceptions which have been (or admit of +being) taken to the arguments adduced, but to deal with such exceptions +at the time when each of these arguments shall have been severally +stated. Again, and lastly, I will arrange the evidence in each case--i. +e. on both sides--under three headings, viz. (A) Indirect, (B) Direct, +and (C) Experimental[34]. + + [34] [The above paragraph is allowed to remain exactly as Mr. + Romanes left it. Chapters V and VI were however not completed. + _See_ note appended to Preface. C. Ll. M.] + + + + +CHAPTER III. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(A.) +_Indirect Evidence in favour of the Inheritance of Acquired Characters._ + + +Starting with the evidence in favour of the so-called Lamarckian +factors, we have to begin with the Indirect--and this without any +special reference to the theories, either of Weismann or of others. + +It has already been shown, while setting forth in the preceding chapter +the antecedent standing of the issue, that in this respect the _prima +facie_ presumption is wholly on the side of the transmission, in greater +degree or less, of acquired characters. Even Weismann allows that all +"_appearances_" point in this direction, while there is no inductive +evidence of the action of natural selection in any one case, either as +regards germs or somas, and therefore, _a fortiori_, of the +"all-sufficiency" of this cause[35]. It is true that in some of his +earlier essays he has argued that there is no small weight of _prima +facie_ evidence in favour of his own views as to the non-inheritance of +acquired characters. This, however, will have to be considered in its +proper place further on. Meanwhile I shall say merely in general terms +that it arises almost entirely from a confusion of the doctrine of +Continuity as absolute with that of Continuity as partial, and +therefore, as admitting of degrees in different cases--which, as already +explained, are doctrines wide as the poles asunder. But, leaving aside +for the present such _prima facie_ evidence as Weismann has adduced on +his side of the issue, I may quote him as a hostile witness to the +weight of this kind of evidence _per contra_, in so far as it has +already been presented in the foregoing chapter. Indeed, Weismann is +much too logical a thinker not to perceive the cogency of the +"appearances" which lie against his view of Continuity as +absolute--although he has not been sufficiently careful in +distinguishing between such Continuity and that which admits of degrees. + + [35] See, especially, his excellent remarks on this point, _Contemp. + Rev._ Sept. 1893. + +We may take it, then, as agreed on all hands that whatever weight merely +_prima facie_ evidence may in this matter be entitled to, is on the side +of what I have termed moderated Lamarckianism: first sight "appearances" +are against the Neo-Darwinian doctrine of the absolute non-inheritance +of acquired characters. + + * * * * * + +Let us now turn to another and much more important line of indirect +evidence in favour of moderated Lamarckianism. + +The difficulty of _excluding the possibility_ of natural selection +having been at work in the case of wild plants and animals has already +been noticed. Therefore we may now appreciate the importance of all +facts or arguments which _attenuate the probability_ of natural +selection having been at work. This may be done by searching for cases +in nature where a congenital structure, although unquestionably +adaptive, nevertheless presents so small an amount of adaptation, that +we can scarcely suppose it to have been arrived at by natural selection +in the struggle for existence, as distinguished from the inheritance of +functionally-produced modifications. For if functionally-produced +modifications are ever transmitted at all, there is no limit to the +minuteness of adaptive values which may thus become congenital; whereas, +in order that any adaptive structure or instinct should be seized upon +and accumulated by natural selection, it must from the very first have +had an adaptive value sufficiently great to have constituted its +presence a matter of life and death in the struggle for existence. Such +structures or instincts must not only have always presented some measure +of adaptive value, but this must always have been sufficiently great to +reach what I have elsewhere called a selection-value. Hence, if we meet +with cases in nature where adaptive structures or instincts present so +low a degree of adaptive value that it is difficult to conceive how they +could ever have exercised any appreciable influence in the battle for +life, such cases may fairly be adduced in favour of the Lamarckian +theory. For example, the Neo-Lamarckian school of the United States is +chiefly composed of palaeontologists; and the reason of this seems to be +that the study of fossil forms--or of species in process of +formation--reveals so many instances of adaptations which in their +nascent condition present such exceedingly minute degrees of adaptive +value, that it seems unreasonable to attribute their development to a +survival of the fittest in the complex struggle for existence. But as +this argument is in my opinion of greatest force when it is applied to +certain facts of physiology with which I am about to deal, I will not +occupy space by considering any of the numberless cases to which the +Neo-Lamarckians apply it within the region of palaeontology[36]. + + [36] There is now an extensive literature within this region. The + principal writers are Cope, Scott and Osborn. Unfortunately, + however, the facts adduced are not crucial as test-cases + between the rival theories--nearly all of them, in fact, being + equally susceptible of explanation by either. + +Turning then to inherited actions, it is here that we might antecedently +expect to find our best evidence of the Lamarckian principles, if these +principles have really had any share in the process of adaptive +evolution. For we know that in the life-time of individuals it is +action, and the cessation of action, which produce nearly all the +phenomena of acquired adaptation--use and disuse in animals being merely +other names for action and the cessation of action. Again, we know that +it is where neuro-muscular machinery is concerned that we meet with the +most conclusive evidence of the remarkable extent to which action is +capable of co-ordinating structures for the ready performance of +particular functions; so that even during the years of childhood +"practice makes perfect" to the extent of organizing neuro-muscular +adjustments, so elaborate and complete as to be indistinguishable from +those which in natural species we recognized as reflex actions on the +one hand, and instinctive actions on the other. Hence, if there be any +such thing as "use-inheritance" at all, it is in the domain of reflex +actions and instinctive actions that we may expect to find our best +evidence of the fact. Therefore I will restrict the present line of +evidence--(A)--to these two classes of phenomena, as together yielding +the best evidence obtainable within this line of argument. + + * * * * * + +The evidence in favour of the Lamarckian factors which may be derived +from the phenomena of reflex action has never, I believe, been pointed +out before; but it appears to me of a more cogent nature than perhaps +any other. In order to do it justice, I will begin by re-stating an +argument in favour of these factors which has already been adduced by +previous writers, and discussed by myself in published correspondence +with several leaders of the ultra-Darwinian school. + +Long ago Professor Broca and Mr. Herbert Spencer pointed to the facts of +co-adaptation, or co-ordination within the limits of the same organism, +as presenting good evidence of Lamarckian principles, working in +association with natural selection. Thus, taking one of Lamarck's own +illustrations, Mr. Spencer argued that there must be numberless +changes--extending to all the organs, and even to all the tissues, of +the animal--which in the course of many generations have conspired to +convert an antelope into a giraffe. Now the point is, that throughout +the entire history of these changes their utility must always have been +dependent on their association. It would be useless that an incipient +giraffe should present the peculiar form of the hind-quarters which we +now perceive, unless at the same time it presented the correspondingly +peculiar form of the fore-quarters; and as each of these great +modifications entails innumerable subordinate modifications throughout +both halves of the creature concerned, the chances must have been +infinitely great against the required association of so many changes +happening to have arisen congenitally in the same individuals by way of +merely fortuitous variation. Yet, if we exclude the Lamarckian +interpretation, which gives an intelligible _cause_ of co-ordination, we +are required to suppose that such a happy concurrence of innumerable +independent variations must have occurred by mere accident--and this on +innumerable different occasions in the bodies of as many successive +ancestors of the existing species. For at each successive stage of the +improvement natural selection (if working alone) must have needed all, +or at any rate most, of the co-ordinated parts to occur in the same +individual organisms[37]. + + [37] For another and better illustration more recently published by + Mr. Spencer, see _The Inadequacy of Natural Selection_, p. 22. + +In alluding to what I have already published upon the difficulty which +thus appears to be presented to his theory, Weismann says, "At no +distant time I hope to be able to consider this objection, and to show +that the apparent support given to the old idea [i. e. of the +transmission of functionally-produced modifications] is really insecure, +and breaks down as soon as it is critically examined[38]." + + [38] _Essays on Heredity_, vol. i. p. 389. + + [For further treatment of the subject under discussion _see_ + Weismann, _The All-sufficiency of Natural Selection_ (Contemp. + Rev. Sept. and Oct. 1893), and _The Effect of External + Influences upon Development_. "Romanes Lecture" 1894, and + Spencer, _Weismannism once more_ (Cont. Rev. Oct. 1894). C. Ll. + M.] + +So much for what Weismann has said touching this matter. But the matter +has also been dealt with both by Darwin and by Wallace. Darwin very +properly distinguishes between the fallacy that "with animals such as +the giraffe, of which the whole structure is admirably co-ordinated for +certain purposes, it has been supposed that all the parts must have been +simultaneously modified[39]," and the sound argument that the +co-ordination itself cannot have been due to natural selection alone. +This important distinction may be rendered more clear as follows. + + [39] _Variation_, &c., vol. ii. p. 206. + +The facts of artificial selection prove that immense modifications of +structure may be caused by a cumulative blending in the same individuals +of characters which were originally distributed among different +individuals. Now, in the parallel case of natural selection the +characters thus blended will usually--if not invariably--be of an +adaptive kind; and their eventual blending together in the same +individuals will be due to free intercrossing of the most fit. But this +_blending of adaptations_ is quite a different matter from the +_occurrence of co-ordination_. For it belongs to the essence of +co-ordination that each of the co-ordinated parts should be destitute of +adaptive value _per se_: the adaptation only begins to arise if all the +parts in question occur associated together in the same individuals +_from the very first_. In this case it is obvious that the analogy of +artificial selection can be of no avail in explaining the facts, since +the difficulty presented has nothing to do with the blending in single +individuals of adaptations previously distributed among different +individuals; it has to do with the simultaneous appearance in single +individuals of a co-adaptation of parts, none of which could ever have +been of any adaptive value had it been previously distributed among +different individuals. Consequently, where Darwin comes to consider this +particular case (or the case of co-adaptation as distinguished from the +blending of adaptations), he freely invokes the aid of the Lamarckian +principles[40]. + + [40] E. g. _Origin of Species_, p. 178. + +Wallace, on the other hand, refuses to do this, and says that "the best +answer to the difficulty" of supposing natural selection to have been +the only cause of co-adaptation may be "found in the fact that the very +thing said to be impossible by variation and natural selection, has been +again and again affected by variation and artificial selection[41]." +This analogy (which Darwin had already and very properly adduced with +regard to the _blending of adaptations_) he enforces by special +illustrations; but he does not appear to perceive that it misses the +whole and only point of the "difficulty" against which it is brought. +For the case which his analogy sustains is not that which Darwin, +Spencer, Broca and others, mean by _co-adaptation_: it is the case of a +blending of _adaptations_. It is not the case where adaptation is _first +initiated in spite of intercrossing_, by a fortuitous concurrence of +variations each in itself being without adaptive value: it is the case +where adaptation is _afterwards increased by means of intercrossing_, +through the blending of variations each of which has always been in +itself of adaptive value. + + [41] _Darwinism_, p. 418. + +From this I hope it will be apparent that the only way in which the +"difficulty" from co-adaptation can be logically met by the +ultra-Darwinian school, is by denying that the phenomenon of +co-adaptation (as distinguished from the blending of adaptations) is +ever to be really met with in organic nature. It may be argued that in +all cases where co-adaptation _appears_ to occur, closer examination +will show that the facts are really due to a blending of adaptations. +The characters A + B + C + D, which are now found united in the same +organism, and, as thus united, all conspiring to a common end, may +originally have been distributed among different organisms, where they +_severally_ subserved some other ends--or possibly the same end, though +in a less efficient manner. Obviously, however, in this case their +subsequent combination in the same organism would not be an instance of +co-adaptation, but merely of an advantageous blending together of +already existing adaptations. This argument, or rejoinder, has in point +of fact been adopted by Professor Meldola, he believes that all cases of +seeming co-adaptation are thus due to a mere blending of +adaptations[42]. Of course, if this position can be maintained, the +whole difficulty from co-adaptation would lapse. But even then it would +lapse on the ground of _fact_. It would not have been overturned, or in +any way affected, by Wallace's _argument_ from artificial selection. +For, in that event, no such argument would be required, and, if adduced, +would be irrelevant, since no one has ever alleged that there is any +difficulty in understanding the mere confluence of adaptations by +free-intercrossing of the best adapted. + + [42] _Nature_, vol. xliii. pp. 410, 557; vol. xliv. pp. 7, 29. I say + "adopted," because I had objected to his quoting the analogy of + artificial selection, and stated, as above, that the only way + to meet Mr. Spencer's "difficulty" was to deny the fact of + co-adaptation as ever occurring in any case. It then appeared + that Professor Meldola agreed with me as to this. But I do not + yet understand why, if such were his view, he began by + endorsing Mr. Wallace's analogy from artificial selection--i. + e. confusing the case of co-adaptation with that of the + blending of adaptations. If any one denies the fact of + co-adaptation, he cannot assist his denial by arguing the + totally different fact that adaptations may be blended by free + intercrossing; for this latter fact has never been questioned, + and has nothing to do with the one which he engaged in + disputing. + +Now, if we are agreed that the only question in debate is the question +of fact whether or not co-adaptation ever occurs in nature, it appears +to me that the best field for debating the question is furnished by the +phenomena of reflex action. I can well perceive that the instances +adduced by Broca and Spencer in support of their common argument--such +as the giraffe, the elk, &c.--are equivocal. But I think that many +instances which may be adduced of reflex action are much more to the +point. _For it belongs to the very nature of reflex action that it +cannot work unless all parts of the machinery concerned are already +present, and already co-ordinated, in the same organism._ It would be +useless, in so far as such action is concerned if the afferent and +efferent nerves, the nerve-centre, and the muscles organically grouped +together, were not all present from the very first in the same +individuals, and from the very first were not co-ordinated as a definite +piece of organic machinery. + +With respect to reflex actions, therefore, it is desirable to begin by +pointing out how widely the adaptations which they involve differ from +those where no manufacture, so to speak, of special machinery is +required. Thus, it is easy to understand how natural selection alone is +capable of gradually accumulating congenital variations in the direction +of protective colouring; of mimicry; of general size, form, mutual +correlation of parts as connected with superior strength, fleetness, +agility, &c.; of greater or less development of particular parts, such +as legs, wings, tails, &c. For in all such cases the adaptation which is +in process of accumulation is from its very commencement and throughout +each of its subsequent stages, of _use_ in the struggle for existence. +And inasmuch as all the individuals of each successive generation vary +round the specific mean which characterized the preceding generation, +there will always be a sufficient number of individuals which present +congenital variations of the kind required for natural selection to +seize upon, without danger of their being swamped by free +intercrossing--as Mr. Wallace has very ably shown in his _Darwinism_. +But this law of averages can apply only to cases where single +structures--or a single group of correlated structures--are already +present, and already varying round a specific mean. The case is quite +different where a _co-ordination_ of structures is required for the +performance of a _previously non-existent_ reflex action. For some, at +least, of these structures must be _new_, as must also be the function +which all of them first conspire to perform. Therefore, neither the new +elements of structure, nor the new combination of structures, can have +been previously given as varying round a specific mean. On the contrary, +a very definite piece of machinery, consisting of many co-ordinated +parts, must somehow or other be originated in a high degree of working +efficiency, before it can be capable of answering its purpose in the +prompt performance of a particular action under particular circumstances +of stimulation. Lastly, such pieces of machinery are always of a highly +delicate character, and usually involve so immensely complex a +co-ordination of mutually dependent parts, that it is only a +physiologist who can fully appreciate the magnitude of the distinction +between "adaptations" of this kind, and "adaptations" of the kind which +arise through natural selection seizing upon congenital variations as +these oscillate round a specific mean. + +Or the whole argument may be presented in another form, under three +different headings, thus:-- + +In the first place, it will be evident from what has just been said, +that such a piece of machinery as is concerned in even the simplest +reflex action cannot have occurred in any considerable number of +individuals of a species, _when it first began to be constructed_. On +the contrary, if its _origin_ were dependent on congenital variations +alone, the needful co-adaptation of parts which it requires can scarcely +have happened to occur in more than a very small percentage of +cases--even if it be held conceivable that by such means alone it should +ever have occurred at all. Hence, instead of preservation and subsequent +improvement having taken place _in consequence of_ free intercrossing +among all individuals of the species (as in the cases of protective +colouring, &c., where adaptation has no reference to any mechanical +co-adaptation of parts), they must have taken place _in spite of_ such +intercrossing. + +In the second place, adaptations due to organic machineries of this kind +differ in another all-important respect from those due to a summation of +adaptive characters which are already present and already varying round +a specific mean. The latter depend for their summation upon the +fact--not merely, as just stated, that they are already present, already +varying round a specific mean, and therefore owe their progressive +evolution to free intercrossing, but also--_that they admit of very +different degrees of adaptation_. It is only because the degree of +adaptation in generation B is superior to that in generation A that +_gradual improvement_ in respect of adaptation is here possible. In the +case of protective resemblance, for example, a very imperfect and merely +accidental resemblance to a leaf, to another insect, &c., may at the +first start have conferred a sufficient degree of adaptive imitation to +count for something in the struggle for life; and, if so, the basis +would be given for a progressive building up by natural selection of +structures and colours in ever-advancing degrees of adaptive +resemblance. There is here no necessity to suppose--nor in point of fact +is it ever supposed, since the supposition would involve nothing short +of a miracle--that such extreme perfection in this respect as we now so +frequently admire has originated suddenly in a single generation, as a +collective variation of a congenital kind affecting simultaneously a +large proportional number of individuals. But in the case of a reflex +mechanism--which may involve even greater marvels of adaptive +adjustment, and _all_ the parts of which must occur in the same +_individuals_ to be of any use--it _is_ necessary to suppose some such +sudden and collective origin in some very high degree of efficiency, if +natural selection has been the only principle concerned in afterwards +perfecting the mechanism. For it is self-evident that a reflex action, +from its very nature, cannot admit of any great differences in its +degrees of adaptation: if it is to work at all, so as to count for +anything in the struggle for life, it must already be given in a state +of working efficiency. So that, unless we invoke either the doctrine of +"prophetic types" or the theory of sudden creations, I confess I do not +see how we are to explain either the origin, or the development, of a +reflex mechanism by means of natural selection alone. + +Lastly, in the third place, _even when reflex mechanisms have been fully +formed_, it is often beyond the power of sober credence to believe that +they now are, or ever can have been, of selective value in the struggle +for existence, as I will show further on. And such cases go to fortify +the preceding argument. For if not conceivably of selective value even +when completely evolved, much less can they conceivably have been so +through all the stages of their complex evolution back to their very +origin. Therefore, supposing for the present that there are such cases +of reflex action in nature, neither their origin nor their development +can conceivably have been due to natural selection alone. The Lamarckian +factors, however, have no reference to degrees of adaptation, any more +than they have to degrees of complexity. No question of value, as +selective or otherwise, can obtain in their case: neither in their case +does any difficulty obtain as regards the co-adaptation of severally +useless parts. + +Now, if all these distinctions between the Darwinian and Lamarckian +principles are valid--and I cannot see any possibility of doubt upon +this point--strong evidence in favour of the latter would be furnished +by cases (if any occur) where structures, actions, instincts, &c., +although of some adaptive value, are nevertheless plainly not of +selective value. According to the ultra-Darwinian theory, no such cases +ought ever to occur: according to the theory of Darwin himself, they +ought frequently to occur. Therefore a good test, or criterion, as +between these different theories of organic evolution is furnished by +putting the simple question of fact--Can we, or can we not, show that +there are cases of adaptation where the degree of adaptation is so small +as to be incompatible with the supposition of its presenting a selective +value? And if we put the wider question--Are there any cases where the +co-adaptation of severally useless parts has been brought about, when +even the resulting whole does not present a selective value?--then, of +course, we impose a still more rigid test. + +Well, notwithstanding the difficulty of proving such a negative as the +absence of natural selection where adaptive development is concerned, I +believe that there are cases which conform to both these tests +simultaneously; and, moreover, that they are to be found in most +abundance where the theory of use-inheritance would most expect them to +occur--namely, in the province of reflex action. For the very essence of +this theory is the doctrine, that constantly associated use of the same +parts for the performance of the same action will progressively organize +those parts into a reflex mechanism--no matter how high a degree of +co-adaptation may thus be reached on the one hand, or how low a degree +of utilitarian value on the other. + +Having now stated the general or abstract principles which I regard as +constituting a defence of the Lamarckian factors, so far as this admits +of being raised on grounds of physiology, we will now consider a few +concrete cases by way of illustration. It is needless to multiply such +cases for the mere purpose of illustration. For, on reading those here +given, every physiologist will at once perceive that they might be added +to indefinitely. The point to observe is, the relation in which these +samples of reflex action stand to the general principles in question; +for there is nothing unusual in the samples themselves. On the contrary, +they are chosen because they are fairly typical of the phenomena of +reflex action in general. + +In our own organization there is a reflex mechanism which ensures the +prompt withdrawal of the legs from any source of irritation supplied to +the feet. For instance, even after a man has broken his spine in such a +manner as totally to interrupt the functional continuity of his spinal +cord and brain, the reflex mechanism in question will continue to +retract his legs when his feet are stimulated by a touch, a burn, &c. +This responsive action is clearly an adaptive action, and, as the man +neither feels the stimulation nor the resulting movement, it is as +clearly a reflex action. The question now is as to the mode of its +origin and development. + +I will not here dwell upon the argument from co-adaptation, because this +may be done more effectually in the case of more complicated reflex +actions, but will ask whether we can reasonably hold that this +particular reflex action--comparatively simple though it is--has ever +been of selective value to the human species, or to the ancestors +thereof? Even in its present fully-formed condition it is fairly +questionable whether it is of any adaptive _value_ at all. The movement +performed is no doubt an adaptive _movement_; but is there any occasion +upon which the reflex mechanism concerned therein can ever have been of +adaptive _use_? Until a man's legs have been paralyzed as to their +voluntary motion, he will always promptly withdraw his feet from any +injurious source of irritation by means of his conscious intelligence. +True, the reflex mechanism secures an almost inappreciable saving in the +time of response to a stimulus, as compared with the time required for +response by an act of will; but the difference is so exceedingly small, +that we can hardly suppose the saving of it in this particular case to +be a matter of any adaptive--much less selective--importance. Nor is it +more easy to suppose that the reflex mechanism has been developed by +natural selection for the purpose of replacing voluntary action when the +latter has been destroyed or suspended by grave spinal injury, +paralysis, coma, or even ordinary sleep. In short, even if for the sake +of argument we allow it to be conceivable that any single human being, +ape, or still more distant ancestor, has ever owed its life to the +possession of this mechanism, we may still be certain that not one in a +million can have done so. And, if this is the case with regard to the +mechanism as now fully constructed, still more must it have been the +case with regard to all the previous stages of construction. For here, +without elaborating the point, it would appear that a process of +construction by survival of the fittest alone is incomprehensible. + +On the other hand, of course, the theory of use-inheritance furnishes a +fully intelligible--whether or not a true--explanation. For those +nerve-centres in the spinal cord which co-ordinate the muscles required +for retracting the feet are the centres used by the will for this +purpose. And, by hypothesis, the frequent use of them for this purpose +under circumstances of stimulation which render the muscular response +appropriate, will eventually establish an organic connexion between such +response and the kind of stimulation to which it is appropriate--even +though there be no utilitarian reason for its establishment[43]. To +invert a phrase of Aristotle, we do not frequently use this mechanism +because we have it (seeing that in our normal condition there is no +necessity for such use); but, by hypothesis, we have it because we have +frequently used its several elements in appropriate combination. + + [43] It may be said, with regard to this particular reflex, that it + may perhaps be, so to speak, a mechanical accident, arising + from the contiguity of the sensory and motor roots in the cord. + But as this suggestion cannot apply to other reflexes presently + to be adduced, it need not be considered. + +I will adduce but one further example in illustration of these general +principles--passing at once from the foregoing case of comparative +simplicity to one of extreme complexity. + +There is a well-known experiment on a brainless frog, which reveals a +beautiful reflex mechanism in the animal, whereby the whole body is +enabled continually to readjust its balance on a book (or any other +plane surface), as this is slowly rotated on a horizontal axis. So long +as the book is lying flat, the frog remains motionless; but as soon as +the book is tilted a little, so that the frog is in danger of slipping +off, all the four feet begin to crawl up the hill; and the steeper the +hill becomes, the faster they crawl. When the book is vertical, the frog +has reached the now horizontal back, and so on. Such being the facts, +the question is--How can the complicated piece of machinery thus implied +have been developed by natural selection? Obviously it cannot have been +so by any of the parts concerned having been originally distributed +among different individuals, and afterwards united in single individuals +by survival (i.e. free intercrossing) of the fittest. In other words, +the case is obviously one of co-adaptation, and not one of the blending +of adaptations. Again, and no less obviously, it is impossible that the +co-adaptation can have been _gradually developed_ by natural selection, +because, in order to have been so, it must by hypothesis have been of +some degree of use in every one of its stages; yet it plainly cannot +have been until it had been fully perfected in all its astonishing +complexity[44]. + + [44] Of course it will be observed that the question is not with + regard to the development of all the nerves and muscles + concerned in this particular process. It is as to the + development of the co-ordinating centres, which thus so + delicately respond to the special stimuli furnished by + variations of angle to the horizon. And it is as inconceivable + in this case of reflex action, as it is in almost every other + case of reflex action, that the highly specialized machinery + required for performing the adaptive function can ever have had + its origin in the performance of any other function. Indeed, a + noticeable peculiarity of reflex mechanisms as a class is the + highly specialized character of the functions which their + highly organized structures subserve. + +Lastly, not only does it thus appear impossible that during all stages +of its development--or while as yet incapable of performing its +intricate function--this nascent mechanism can have had any adaptive +value; but even as now fully developed, who will venture to maintain +that it presents any selective value? As long as the animal preserves +its brain, it will likewise preserve its balance, by the exercise of its +intelligent volition. And, if the brain were in some way destroyed, the +animal would be unable to breed, or even to feed; so that natural +selection can never have had any _opportunity_, so to speak, of +developing this reflex mechanism in brainless frogs. On the other hand, +as we have just seen, we cannot perceive how there can ever have been +any _raison d'être_ for its development in normal frogs--even if its +development were conceivably possible by means of this agency. But if +practice makes perfect in the race, as it does in the individual, we can +immediately perceive that the constant habit of correctly adjusting its +balance may have gradually developed, in the batrachian organization, +this non-necessary reflex[45]. + + [45] We meet with a closely analogous reflex mechanism in brainless + vertebrata of other kinds; but these do not furnish such good + test cases, because the possibility of natural selection cannot + be so efficiently attenuated. The perching of brainless birds, + for instance, at once refers us to the roosting of sleeping + birds, where the reflex mechanism concerned is clearly of high + adaptive value. Therefore such a case is not available as a + test, although the probability is that birds have inherited + their balancing mechanisms from their sauropsidian ancestors, + where it would have been of no such adaptive importance. + +And, of course, this example--like that of withdrawing the feet from a +source of stimulation, which a frog will do as well as a man--does not +stand alone. Without going further a-field than this same animal, any +one who reads, from our present point of view, Goltz's work on the +reflex actions of the frog, will find that the great majority of +them--complex and refined though most of them are--cannot conceivably +have ever been of any use to any frog that was in undisturbed possession +of its brain. + +Hence, not to occupy space with a reiteration of facts all more or less +of the same general kind, and therefore all presenting identical +difficulties to ultra-Darwinian theory, I shall proceed to give two +others which appear to me of particular interest in the present +connexion, because they furnish illustrations of reflex actions in a +state of only partial development, and are therefore at the present +moment demonstrably useless to the animal which displays them. + +Many of our domesticated dogs, when we gently scratch their sides and +certain other parts of the body, will themselves perform scratching +movements with the hind leg of the same side as that upon which the +irritation is being supplied. According to Goltz[46], this action is a +true reflex; for he found that it is performed equally well in a dog +which has been deprived of its cerebral hemispheres, and therefore of +its normal volition. Again, according to Haycraft[47], this reflex is +congenital, or not acquired during the life-time of each individual dog. +Now, although the action of scratching is doubtless adaptive, it appears +to me incredible that it could ever have become organized into a +congenital reflex by natural selection. For, in order that it should, +the scratching away fleas would require to have been a function of +selective value. Yet, even if the irritation caused by fleas were +supposed to be so far fatal in the struggle for existence, it is certain +that they would always be scratched away by the conscious intelligence +of each individual dog; and, therefore, that no advantage could be +gained by organizing the action into a reflex. On the other hand, if +acquired characters are ever in any degree transmitted, it is easy to +understand how so frequently repeated an action should have become, in +numberless generations of dogs, congenitally automatic. + + [46] _Pflüger's Archiv_, Bd. xx. s. 23 (1879). + + [47] _Brain_, part xlviii, pp. 516-19 (1889).--There is still better + proof of this in the case of certain rodents. For instance, + observing that rats and mice are under the necessity of very + frequently scratching themselves with their hind-feet, I tried + the experiment of removing the latter from newly-born + individuals--i.e. before the animals were able to co-ordinate + their movements, and therefore before they had ever even + attempted to scratch themselves. Notwithstanding that they were + thus destitute of individual experience with regard to the + benefit of scratching, they began their scratching movements + with their stumps as soon as they were capable of executing + co-ordinated movements, and afterwards continued to do so till + the end of their lives with as much vigour and frequency as + unmutilated animals. Although the stumps could not reach the + seats of irritation which were bent towards them, they used to + move rapidly in the air for a time sufficient to have given the + itching part a good scratch, had the feet been present--after + which the animals would resume their sundry other avocations + with apparent satisfaction. These facts showed the hereditary + response to irritation by parasites to be so strong, that even + a whole life-time's experience of its futility made no + difference in the frequency or the vigour thereof. + +So much for the general principle of selective value as applied to this +particular case. And similarly, of course, we might here repeat the +application of all the other general principles, which have just been +applied in the two preceding cases. But it is only one of these other +general principles which I desire in the present case specially to +consider, for the purpose of considering more closely than hitherto the +difficulty which this principle presents to ultra-Darwinian theory. + +The difficulty to which I allude is that of understanding how all the +stages in the _development_ of a reflex action can have been due to +natural selection, seeing that, before the reflex mechanism has been +sufficiently elaborated to perform its function, it cannot have +presented any degree of utility. Now the particular force of the present +example, the action of scratching--as also of the one to +follow--consists in the fact that it is a case where a reflex action is +not yet completely organized. It appears to be only in course of +construction, so that it is neither invariably present, nor, when it is +present, is it ever fully adapted to the performance of its function. + +That it is not invariably present (when the brain is so) may be proved +by trying the simple experiment on a number of puppies--and also of +full-grown dogs. Again, that even when it is present it is far from +being fully adapted to the performance of its function, may be proved by +observing that only in rare instances does the scratching leg succeed in +scratching the place which is being irritated. The movements are made +more or less at random, and as often as not the foot fails to touch the +body at any place at all. Hence, although we have a "prophecy" of a +reflex action well designed for the discharge of a particular function, +at present the machinery is not sufficiently perfected for the adequate +discharge of that function. In this important respect it differs from +the otherwise closely analogous reflex action of the frog, whereby the +foot of the hind leg is enabled to localize with precision a seat of +irritation on the side of the body. But this beautiful mechanism in the +frog cannot have sprung into existence ready formed at any historical +moment in the past history of the phyla. It must have been the subject +of a more or less prolonged evolution, in some stage of which it must +presumably have resembled the now nascent scratching reflex of the dog, +in making merely abortive attempts at localizing the seat of +irritation--supposing, of course, that some physiologist had been there +to try the experiment by first removing the brain. Now, even if one +could imagine it to be, either in the frog or in the dog, a matter of +selective importance that so exceedingly refined a mechanism should have +been developed for the sole purpose of inhibiting the bites of +parasites--which in every normal animal would certainly be discharged by +an _intentional_ performance of the movements in question,--even if, in +order to save an hypothesis at all costs, we make so violent a +supposition as this, still we should do so in vain. For it would still +remain undeniably certain that the reflex mechanism is _not_ of any +selective value. Even now the mechanism in the dog is not sufficiently +precise to subserve the only function which occasionally and abortively +it attempts to perform. Thus it has all the appearance of being but an +imitating shadow of certain neuro-muscular adjustments, which have been +habitually performed in the canine phyla by a volitional response to +cutaneous irritation. Were it necessary, this argument might be +strengthened by observing that the reflex action is positively +_improved_ by removal of the brain. + +The second example of a nascent reflex in dogs which I have to mention +is as follows. + +Goltz found that his brainless dogs, when wetted with water, would shake +themselves as dry as possible, in just the same way as normal dogs will +do under similar circumstances. This, of course, proves that the shaking +movements may be performed by a reflex mechanism, which can have no +other function to perform in the organization of a dog, and which, +besides being of a highly elaborate character, will respond only to a +very special kind of stimulation. Now, here also I find that the +mechanism is congenital, or not acquired by individual experience. For +the puppies on which I experimented were kept indoors from the time of +their birth--so as never to have had any experience of being wetted by +rain, &c.--till they were old enough to run about with a full power of +co-ordinating their general movements. If these young animals were +suddenly plunged into water, the shock proved too great: they would +merely lie and shiver. But if their feet alone were wetted, by being +dipped in a basin of water, the puppies would soon afterwards shake +their heads in the peculiar manner which is required for shaking water +off the ears, and which in adult dogs constitutes the first phase of a +general shaking of the whole body. + +Here, then, we seem to have good evidence of all the same facts which +were presented in the case of the scratching reflex. In the first +place, co-adaptation is present in a very high degree, because this +shaking reflex in the dog, unlike the skin-twitching reflex in the +horse, does not involve only a single muscle, or even a single group of +muscles; it involves more or less the co-ordinated activity of many +voluntary muscles all over the body. Such, at any rate, is the case when +the action is performed by the intelligent volition of an adult dog; and +if a brainless dog, or a young puppy, does not perform it so extensively +or so vigorously, this only goes to prove that the reflex has not yet +been sufficiently developed to serve as a substitute for intelligent +volition--i.e. that it is _useless_, or a mere organic shadow of the +really adaptive substance. Again, even if this nascent reflex had been +so far developed as to have been capable of superseding voluntary +action, still we may fairly doubt whether it could have proved of +selective value. For it is questionable whether the immediate riddance +of water after a wetting is a matter of life and death to dogs in a +state of nature. Moreover, even if it were, every individual dog would +always have got rid of the irritation, and so of the danger, by means of +a _voluntary_ shake--with the double result that natural selection has +never had any opportunity of gradually building up a special reflex +mechanism for the purpose of securing a shake, and that the canine race +have not had to wait for any such unnecessary process. Lastly, such a +process, besides being unnecessary, must surely have been, under any +circumstances, impossible. For even if we were to suppose--again for the +sake of saving an hypothesis at any cost--that the presence of a +fully-formed shaking reflex is of selective value in the struggle for +existence, it is perfectly certain that all the stages through which the +construction of so elaborate a mechanism must have passed could not have +been, under any circumstances, of any such value. + +But, it is needless to repeat, according to the hypothesis of +use-inheritance, there is no necessity to suppose that these incipient +reflex mechanisms _are_ of any value. If function produces structure in +the race as it does in the individual, the voluntary and frequently +repeated actions of scratching and shaking may very well have led to an +organic integration of the neuro-muscular mechanisms concerned. Their +various parts having been always co-ordinated for the performance of +these actions by the intelligence of innumerable dogs in the past, their +co-adapted activity in their now automatic responses to appropriate +stimuli presents no difficulty. And the consideration that neither in +their prospectively more fully developed condition, nor, _a fortiori_, +in their present and all previous stages of evolution, can these reflex +mechanisms be regarded as presenting any selective--or even so much as +any adaptive--value, is neither more nor less than the theory of +use-inheritance would expect. + +Thus, with regard to the phenomena of reflex action in general, all the +facts are such as this theory requires, while many of the facts are such +as the theory of natural selection alone cannot conceivably explain. +Indeed, it is scarcely too much to say, that most of the facts are such +as directly contradict the latter theory in its application to them. +But, be this as it may, at present there are only two hypotheses in the +field whereby to account for the facts of adaptive evolution. One of +these hypotheses is universally accepted, and the only question is +whether we are to regard it as _alone_ sufficient to explain _all_ the +facts. The other hypothesis having been questioned, we can test its +validity only by finding cases which it is fully capable of explaining, +and which do not admit of being explained by its companion hypothesis. I +have endeavoured to show that we have a large class of such cases in the +domain of reflex action, and shall next endeavour to show that there is +another large class in the domain of instinct. + + * * * * * + +If instinct be, as Professor Hering, Mr. Samuel Butler, and others have +argued, "hereditary habit"--i. e. if it comprises an element of +transmitted experience--we at once find a complete explanation of many +cases of the display of instinct which otherwise remain inexplicable. +For although a large number--or even, as I believe, a large majority--of +instincts are explicable by the theory of natural selection alone, or by +supposing that they were gradually developed by the survival of +fortuitous variations in the way of advantageous psychological +peculiarities, this only applies to comparatively simple instincts, such +as that of a protectively coloured animal exhibiting a preference for +the surroundings which it resembles, or even adopting attitudes in +imitation of objects which occur in such surroundings. But in all cases +where instincts become complex and refined, we seem almost compelled to +accept Darwin's view that their origin is to be sought in consciously +intelligent adjustments on the part of ancestors. + +Thus, to give only one example, a species of Sphex preys upon +caterpillars, which it stings in their nerve-centres for the purpose of +paralyzing, without killing them. The victims, when thus rendered +motionless, are then buried with the eggs of the Sphex, in order to +serve as food for her larvae which subsequently develop from these eggs. +Now, in order thus to paralyze a caterpillar, the Sphex has to sting it +successively in nine minute and particular points along the ventral +surface of the animal--and this the Sphex unerringly does, to the +exclusion of all other points of the caterpillar's anatomy. Well, such +being the facts--according to M. Fabre, who appears to have observed +them carefully--it is conceivable enough, as Darwin supposed[48], that +the ancestors of the Sphex, being like many other hymenopterous insects +highly intelligent, should have observed that on stinging caterpillars +in these particular spots a greater amount of effect was produced than +could be produced by stinging them anywhere else; and, therefore, that +they habitually stung the caterpillars in these places only, till, in +course of time, this originally intelligent habit became by heredity +instinctive. But now, on the other hand, if we exclude the possibility +of this explanation, it appears to me incredible that such an instinct +should ever have been evolved at all; for it appears to me incredible +that natural selection, unaided by originally intelligent action, could +ever have developed such an instinct out of merely fortuitous +variations--there being, by hypothesis, nothing to _determine_ +variations of an insect's mind in the direction of stinging caterpillars +only in these nine intensely localized spots[49]. + + [48] For details of his explanation of this particular case, for + which I particularly inquired, see _Mental Evolution in + Animals_, pp. 301-2. + + [49] Note B. + +Again, there are not a few instincts which appear to be wholly useless +to their possessors, and others again which appear to be even +deleterious. The dusting over of their excrement by certain +freely-roaming carnivora; the choice by certain herbivora of particular +places on which to void their urine, or in which to die; the howling of +wolves at the moon; purring of cats, &c., under pleasurable emotion; and +sundry other hereditary actions of the same apparently unmeaning kind, +all admit of being readily accounted for as useless habits originally +acquired in various ways, and afterwards perpetuated by heredity, +because not sufficiently deleterious to have been stamped out by natural +selection[50]. But it does not seem possible to explain them by survival +of the fittest in the struggle for existence. + + [50] For fuller treatment see _Mental Evolution in Animals_, pp. + 274-285, 378-379, 381-383. + +Finally, in the case of our own species, it is self-evident that the +aesthetic, moral, and religious instincts admit of a natural and easy +explanation on the hypothesis of use-inheritance, while such is by no +means the case if that hypothesis is rejected. Our emotions of the +ludicrous, of the beautiful, and of the sublime, appear to be of the +nature of hereditary instincts; and be this as it may, it would further +appear that, whatever else they may be, they are certainly not of a +life-preserving character. And although this cannot be said of the +moral sense when the theory of natural selection is extended from the +individual to the tribe, still, when we remember the extraordinary +complexity and refinement to which they have attained in civilized man, +we may well doubt whether they can have been due to natural selection +alone. But space forbids discussion of this large and important question +on the present occasion. Suffice it therefore to say, that I doubt not +Weismann himself would be the first to allow that his theory of heredity +encounters greater difficulties in the domain of ethics than in any +other--unless, indeed, it be that of religion[51]. + + [51] For an excellent essay on the deleterious character of early + forms of religion from a biological point of view, see the Hon. + Lady Welby, _An Apparent Paradox in Mental Evolution_ (Journ. + Anthrop. Inst. May 1891). + + * * * * * + +I have now given a brief sketch of the indirect evidence in favour of +the so-called Lamarckian factors, in so far as this appears fairly +deducible from the facts of reflex action and of instinct. It will now +be my endeavour to present as briefly what has to be said against this +evidence. + +As previously observed, the facts of reflex action have not been +hitherto adduced in the present connexion. This has led me to occupy +considerably more space in the treatment of them than those of instinct. +On this account, also, there is here nothing to quote, or to consider, +_per contra_. On the other hand, however, Weismann has himself dealt +with the phenomena of instinct in animals, though not, I think, in +man--if we except his brilliant essay on music. Therefore let us now +begin this division of our subject by briefly stating, and considering, +what he has said upon the subject. + +The answer of Weismann to difficulties which arise against the +ultra-Darwinian theory in the domain of instinct, is as follows:-- + + "The necessity for extreme caution in appealing to the supposed + hereditary effects of use, is well shown in the case of those + numerous instincts which only come into play once in a life-time, + and which do not therefore admit of improvement by practice. The + queen-bee takes her nuptial flight only once, and yet how many and + complex are the instincts and the reflex mechanisms which come into + play on that occasion. Again, in many insects the deposition of + eggs occurs but once in a life-time, and yet such insects always + fulfil the necessary conditions with unfailing accuracy[52]." + + [52] _Essays_, i. p. 93. + +But in this rejoinder the possibility is forgotten, that although such +actions are _now_ performed only once in the individual life-time, +_originally_--i.e. when the instincts were being developed in a remote +ancestry--they may have been performed on many frequent and successive +occasions during the individual life-time. In all the cases quoted by +Weismann, instincts of the kind in question bear independent evidence of +high antiquity, by occurring in whole genera (or even families), by +being associated with peculiar and often highly evolved structures +required for their performance, and so on. Consequently, in these cases +ample time has been allowed for subsequent changes of habit, and of +seasonal alterations with respect to propagation--both these things +being of frequent and facile occurrence among animals of all kinds, even +within periods which fall under actual observation. Nevertheless, I do +not question that there are instinctive activities which, as far as we +are able to see, can never have been performed more than once in each +individual life-time[53]. The fact, however, only goes to show what is +fully admitted--that some instincts (and even highly complex instincts) +have apparently been developed by natural selection alone. Which, of +course, is not equivalent to showing that all instincts must have been +developed by natural selection alone. The issue is not to be debated on +general grounds like this, but on those of particular cases. Even if it +were satisfactorily proved that the instincts of a queen-bee have been +developed by natural selection, it would not thereby be proved that such +has been the case with the instincts of a Sphex wasp. One can very well +understand how the nuptial flight of the former, with all its associated +actions, may have been brought about by natural selection alone; but +this does not help us to understand how the peculiar instincts of the +latter can have been thus caused. + + [53] See _Mental Evolution in Animals_, pp. 377-8. + +Strong evidence in favour of Weismann's views does, however, at first +sight seem to be furnished by social hymenoptera in other respects. For +not only does the queen present highly specialized and altogether +remarkable instincts; but the neuters present totally different and even +still more remarkable instincts--which, moreover, are often divided into +two or more classes, corresponding with the different "castes." Yet the +neuters, being barren females, never have an opportunity of bequeathing +their instincts to progeny. Thus it appears necessary to suppose that +the instincts of all the different castes of neuters are latent in the +queen and drones, together with the other instincts which are patent in +both. Lastly, it seems necessary to suppose that all this wonderful +organization of complex and segregated instincts must have been built up +by natural selection acting exclusively on the queens and drones--seeing +that these exercise their own instincts only once in a life-time, while, +as just observed, the neuters cannot possibly bequeath their individual +experience to progeny. Obviously, however, natural selection must here +be supposed to be operating at an immense disadvantage; for it must have +built up the often diverse and always complex instincts of neuters, not +directly, but indirectly through the queens and drones, which never +manifest any of these instincts themselves. + +Now Darwin fully acknowledged the difficulty of attributing these +results to the unaided influence of natural selection; but the fact of +neuter insects being unable to propagate seemed to him to leave no +alternative. And so it seems to Weismann, who accordingly quotes these +instincts in support of his views. And so it seemed to me, until my work +on _Animal Intelligence_ was translated into French, and an able Preface +was supplied to that translation by M. Perrier. In this Preface it is +argued that we are not necessarily obliged to exclude the possibility of +Lamarckian principles having operated in the original formation of these +instincts. On the contrary, if such principles ever operate at all, +Perrier shows that here we have a case where it is virtually certain +that they must have operated. For although neuter insects are now unable +to propagate, their organization indicates--if it does not actually +prove--that they are descended from working insects which were able to +propagate. Thus, in all probability, what we now call a "hive" was +originally a society of sexually mature insects, all presenting the same +instincts, both as to propagation and to co-operation. When these +instincts, thus common to all individuals composing the hive, had been +highly perfected, it became of advantage in the struggle for existence +(between different hives or communities) that the functions of +reproduction should devolve more upon some individuals, while those of +co-operation should devolve more upon others. Consequently, this +division of labour began, and gradually became complete, as we now find +it in bees and ants. Perrier sustains the hypothesis thus briefly +sketched by pointing to certain species of social hymenoptera where we +may actually observe different stages of the process--from cases where +all the females of the hive are at the same time workers and breeders, +up to the cases where the severance between these functions has become +complete. Therefore, it seems to me, it is no longer necessary to +suppose that in these latter cases all the instincts of the (now) barren +females can only have been due to the unaided influence of natural +selection. + +Nevertheless, although I think that Perrier has made good his position +thus far, that his hypothesis fails to account for some of the instincts +which are manifested by neuter insects, such as those which, so far as I +can see, must necessarily be supposed to have originated after the +breeding and working functions had become separated--seeing that they +appear to have exclusive reference to this peculiar state of matters. +Possibly, however, Perrier might be able to meet each of these +particular instincts, by showing how they could have arisen out of +simpler beginnings, prior to the separation of the two functions in +question. There is no space to consider such possibilities in detail; +but, until this shall have been done, I do not think we are entitled to +conclude that the phenomena of instinct as presented by neuter insects +are demonstrably incompatible with the doctrines of Lamarck--or, that +these phenomena are available as a logical proof of the unassisted +agency of natural selection in the case of instincts in general[54]. + + [54] [See H. Spencer, _The Inadequacy of Natural Selection, A + Rejoinder to Professor Weismann_, Contemp. Rev. 1893; and + _Weismannism once more_, Ibid. Oct. 1894; Weismann, _The + All-sufficiency of Natural Selection_, Ibid. 1893; and _The + Effect of External Influences upon Development_, "Romanes + Lecture" 1894: also _Neuter Insects and Lamarckism_, W. Platt + Ball, Natural Science, Feb. 1894, and _Neuter Insects and + Darwinism_, J. T. Cunningham, Ibid. April 1894. C. Ll. M.] + + +(B.) +_Inherited Effects of Use and of Disuse._ + +There is no doubt that Darwin everywhere attaches great weight to this +line of evidence. Nevertheless, in my opinion, there is equally little +doubt that, taken by itself, it is of immeasurably less weight than +Darwin supposed. Indeed, I quite agree with Weismann that the whole of +this line of evidence is practically worthless; and for the following +reasons. + +The evidence on which Darwin relied to prove the inherited effects of +use and disuse was derived from his careful measurements of the increase +or decrease which certain bones of our domesticated animals have +undergone, as compared with the corresponding bones of ancestral stocks +in a state of nature. He chose domesticated animals for these +investigations, because, while yielding unquestionable cases of +increased or diminished use of certain organs over a large number of +sequent generations, the results were not complicated by the possible +interference of natural selection on the one hand, or by that of the +economy of nutrition on the other. For "with highly-fed domesticated +animals there seems to be no economy of growth, or any tendency to the +elimination of superfluous details[55];" seeing that, among other +considerations pointing in the same direction, "structures which are +rudimentary in the parent species, sometimes become partially +re-developed in our domesticated productions[56]." + + [55] _Variation of Plants and Animals_, vol. ii. p. 289. + + [56] _Ibid._ p. 346. + +The method of Darwin's researches in this connexion was as follows. +Taking, for example, the case of ducks, he carefully weighed and +measured the wing-bones and leg-bones of wild and tame ducks; and he +found that the wing-bones were smaller, while the leg-bones were larger, +in the tame than in the wild specimens. These facts he attributed to +many generations of tame ducks using their wings less, and their legs +more, than was the case with their wild ancestry. Similarly he compared +the leg-bones of wild rabbits with those of tame ones, and so forth--in +all cases finding that where domestication had led to increased use of a +part, that part was larger than in the wild parent stock; while the +reverse was the case with parts less used. Now, although at first sight +these facts certainly do seem to yield good evidence of the inherited +effects of use and disuse, they are really open to the following very +weighty objections. + +First of all, there is no means of knowing how far the observed effects +may have been due to increased or diminished use during only the +individual life-time of each domesticated animal. Again, and this is a +more important point, in all Darwin's investigations the increase or +decrease of a part was estimated, not by directly comparing, say the +wing-bones of a domesticated duck with the wing-bones of a wild duck, +but by comparing the _ratio_ between the wing and leg bones of a tame +duck with the _ratio_ between the wing and leg bones of a wild duck. +Consequently, if there be any reason to doubt the supposition that a +really inherited decrease in the size of a part thus estimated is due to +the inherited effects of disuse, such a doubt will also extend to the +evidence of increased size being due to the inherited effects of use. +Now there is the gravest possible doubt lying against the supposition +that any really inherited decrease in the size of a part is due to the +inherited effects of disuse. For it may be--and, at any rate to some +extent, must be--due to another principle, which it is strange that +Darwin should have overlooked. This is the principle which Weismann has +called Panmixia, and which cannot be better expressed than in his own +words:-- + + "A goose or a duck must possess strong powers of flight in the + natural state, but such powers are no longer necessary for + obtaining food when it is brought into the poultry-yard; so that a + rigid selection of individuals with well-developed wings at once + ceases among its descendants. Hence, in the course of generations, + a deterioration of the organs of flight must necessarily + ensue[57]." + + [57] _Essays_, i. p. 90. + +Or, to state the case in another way: if any structure which was +originally built up by natural selection on account of its use, ceases +any longer to be of so much use, in whatever degree it ceases to be of +use, in that degree will the premium before set upon it by natural +selection be withdrawn. And the consequence of this withdrawal of +selection as regards that particular part will be to allow the part to +degenerate in successive generations. Such is the principle which +Weismann calls Panmixia, because, by the withdrawal of selection from +any particular part, promiscuous breeding ensues with regard to that +part. And it is easy to see that this principle must be one of very +great importance in nature; because it must necessarily come into +operation in all cases where any structure or any instinct has, through +any change in the environment or in the habits of a species, ceased to +be useful. It is likewise easy to see that its effect must be the same +as that which was attributed by Darwin to the inherited effect of +disuse; and, therefore, that the evidence on which he relied in proof of +the inherited effects both of use and of disuse is vitiated by the fact +that the idea of Panmixia did not occur to him. + +Here, however, it may be said that the idea first occurred to me[58] +just after the publication of the last edition of the _Origin of +Species_. I called the principle the Cessation of Selection--which I +still think a better, because a more descriptive, term than Panmixia; +and at that time it appeared to me, as it now appears to Weismann, +entirely to supersede the necessity of supposing that the effect of +disuse is ever inherited in any degree at all. Thus it raised the whole +question as to the admissibility of Lamarckian principles in general; or +the question on which we are now engaged touching the possible +inheritance of acquired, as distinguished from congenital, characters. +But on discussing the matter with Mr. Darwin, he satisfied me that the +larger question was not to be so easily closed. That is to say, although +he fully accepted the principle of the Cessation of Selection, and as +fully acknowledged its obvious importance, he convinced me that there +was independent evidence for the transmission of acquired characters, +sufficient in amount to leave the general structure of his previous +theory unaffected by what he nevertheless recognized as a factor which +must necessarily be added. All this I now mention in order to show that +the issue which Weismann has raised since Darwin's death was expressly +contemplated during the later years of Darwin's life. For if the idea of +Panmixia--in the absence of which Weismann's entire system would be +impossible--had never been present to Darwin's mind, we should have been +left in uncertainty how he would have regarded this subsequent revolt +against what are generally called the Lamarckian principles[59]. + + [58] _Nature_, vol. ix. pp. 361-2, 440-1; and vol. x. p. 164. + + [59] Appendix I. + +Moreover, in this connexion we must take particular notice that the +year after I had published these articles on the Cessation of Selection, +and discussed with Mr. Darwin the bearing of this principle on the +question of the transmission of acquired characters, Mr. Galton followed +with his highly important essay on Heredity. For in this essay Mr. +Galton fully adopted the principle of the Cessation of Selection, and +was in consequence the first publicly to challenge the Lamarckian +principles--pointing out that, if it were thus possible to deny the +transmission of acquired characters _in toto_, "we should be relieved +from all further trouble"; but that, if such characters are transmitted +"in however faint a degree, a complete theory of heredity must account +for them." Thus the question which, in its revived condition, is now +attracting so much attention, was propounded in all its parts some +fifteen or sixteen years ago; and no additional facts or new +considerations of any great importance bearing upon the subject have +been adduced since that time. In other words, about a year after my own +conversations with Mr. Darwin, the whole matter was still more +effectively brought before his notice by his own cousin. And the result +was that he still retained his belief in the Lamarckian factors of +organic evolution, even more strongly than it was retained either by Mr. +Galton or myself[60]. + + [60] For a fuller statement of Mr. Galton's theory of Heredity, and + its relation to Weismann's, see _An Examination of + Weismannism_. + +We have now considered the line of evidence on which Darwin chiefly +relied in proof of the transmissibility of acquired characters; and it +must be allowed that this line of evidence is practically worthless. +What he regarded as the inherited effects of use and of disuse may be +entirely due to the cessation of selection in the case of our +domesticated animals, combined with an active _reversal_ of selection in +the case of natural species. And in accordance with this view is the +fact that the degeneration of disused parts proceeds much further in the +case of wild species than it does in that of domesticated varieties. For +although it may be said that in the case of wild species more time has +been allowed for a greater accumulation of the inherited effects of +disuse than can have been the case with domesticated varieties, the +alternative explanation is at least as probable--that in the case of +wild species the merely negative, or passive, influence of the +_cessation_ of selection has been continuously and powerfully assisted +by the positive, or active, influence of the _reversal_ of selection, +through economy of growth and the general advantage to be derived from +the abolition of useless parts[61]. + + [61] For a fuller explanation of the important difference between + the mere cessation and the actual reversal of selection, see + Appendix I. + +The absence of any good evidence of this direct kind in favour of +use-inheritance will be rendered strikingly apparent to any one who +reads a learned and interesting work by Professor Semper[62]. His object +was to show the large part which he believed to have been played by +external conditions of life in directly modifying organic types--or, in +other words, of proving that side of Lamarckianism which refers to the +immediate action of the environment, whether with or without the +co-operation of use-inheritance and natural selection. Although Semper +gathered together a great array of facts, the more carefully one reads +his book the more apparent does it become that no single one of the +facts is in itself conclusive evidence of the transmission to progeny of +characters which are acquired through use-inheritance or through direct +action of the environment. Every one of the facts is susceptible of +explanation on the hypothesis that the principle of natural selection +has been the only principle concerned. This, however, it must be +observed, is by no means equivalent to proving that characters thus +acquired are not transmitted. As already pointed out, it is +impracticable with species in a state of nature to dissociate the +distinctively Darwinian from the possibly Lamarckian factors; so that +even if the latter are largely operative, we can only hope for direct +evidence of the fact from direct experiments on varieties in a state of +domestication. To this branch of our subject, therefore, we will now +proceed. + + [62] _Animal Life_, International Scientific Series, vol. xxxi. + + + + +CHAPTER IV. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(C.) +_Experimental Evidence in favour of the Inheritance of Acquired +Characters._ + + +Notwithstanding the fact already noticed, that no experiments have +hitherto been published with reference to the question of the +transmission of acquired characters[63], there are several researches +which, with other objects in view, have incidentally yielded seemingly +good evidence of such transmission. The best-known of these +researches--and therefore the one with which I shall begin--is that of +Brown-Séquard touching the effects of certain injuries of the nervous +system in guinea-pigs. + + [63] The experiments of Galton and Weismann upon this subject are + nugatory, as will be shown later on. But since the above was + written an important research has been published by Mr. + Cunningham, of the Marine Biological Association. For a full + account I must refer the reader to his forthcoming paper in the + _Philosophical Transactions_. The following is his own + statement of the principal results:-- + + "A case which I have myself recently investigated + experimentally seems to me to support very strongly the theory + of the inheritance of acquired characters, I have shown that in + normal flat-fishes, if the lower side be artificially exposed + to light for a long time, pigmentation is developed on that + side; but when the exposure is commenced while the specimens + are still in process of metamorphosis, when pigment-cells are + still present on the lower side, the action of light does not + prevent the disappearance of these pigment-cells. They + disappear as in individuals living under normal conditions, but + after prolonged exposure pigment-cells reappear. The first fact + proves that the disappearance of the pigment-cells from the + lower side in the metamorphosis is an hereditary character, and + not a change produced in each individual by the withdrawal of + the lower side from the action of light. On the other hand, the + experiments show that the absence of pigment-cells from the + lower side throughout life is due to the fact that light does + not act upon that side, for, when it is allowed to act, + pigment-cells appear. It seems to me the only reasonable + conclusion from these facts is, that the disappearance of + pigment-cells was originally due to the absence of light, and + that this change has now become hereditary. The pigment-cells + produced by the action of light on the lower side are in all + respects similar to those normally present on the upper side of + the fish. If the disappearance of the pigment-cells were due + entirely to a variation of the germ-plasm, no external + influence could cause them to reappear, and, on the other hand, + if there were no hereditary tendency, the colouration of the + lower side of the flat-fish when exposed would be rapid and + complete."--_Natural Science_, Oct. 1893. + +During a period of thirty years Brown-Séquard bred many thousands of +guinea-pigs as material for his various researches; and in those whose +parents had not been operated upon in the ways to be immediately +mentioned, he never saw any of the peculiarities which are about to be +described. Therefore the hypothesis of coincidence, at all events, must +be excluded. The following is his own summary of the results with which +we are concerned:-- + + 1st. Appearance of epilepsy in animals born of parents which had + been rendered epileptic by an injury to the spinal cord. + + 2nd. Appearance of epilepsy also in animals born of parents which + had been rendered epileptic by section of the sciatic nerve. + + 3rd. A change in the shape of the ear in animals born of parents in + which such a change was the effect of a division of the cervical + sympathetic nerve. + + 4th. Partial closure of the eyelids in animals born of parents in + which that state of the eyelids had been caused either by section + of the cervical sympathetic nerve, or the removal of the superior + cervical ganglion. + + 5th. Exophthalmia in animals born of parents in which an injury to + the restiform body had produced that protrusion of the eyeball. + This interesting fact I have witnessed a good many times, and seen + the transmission of the morbid state of the eye continue through + four generations. In these animals, modified by heredity, the two + eyes generally protruded, although in the parents usually only one + showed exophthalmia, the lesion having been made in most cases only + on one of the corpora restiformia. + + 6th. Haematoma and dry gangrene of the ears in animals born of + parents in which these ear-alterations had been caused by an injury + to the restiform body near the nib of the calamus. + + 7th. Absence of two toes out of the three of the hind leg, and + sometimes of the three, in animals whose parents had eaten up their + hind-leg toes which had become anaesthetic from a section of the + sciatic nerve alone, or of that nerve and also of the crural. + Sometimes, instead of complete absence of the toes, only a part of + one or two or three was missing in the young, although in the + parent not only the toes but the whole foot were absent (partly + eaten off, partly destroyed by inflammation, ulceration, or + gangrene.) + + 8th. Appearance of various morbid states of the skin and hair of + the neck and face in animals born of parents having had similar + alterations in the same parts, as effects of an injury to the + sciatic nerve. + +These results[64] have been independently vouched for by two of +Brown-Séquard's former assistants--Dr. Dupuy, and the late Professor +Westphal. Moreover, his results with regard to epilepsy have been +corroborated also by Obersteiner[65]. I may observe, in passing, that +this labour of testing Brown-Séquard's statements is one which, in my +opinion, ought rather to have been undertaken, if not by Weismann +himself, at all events by some of his followers. Both he and they are +incessant in their demand for evidence of the transmission of acquired +characters; yet they have virtually ignored the foregoing very +remarkable statements. However, be this as it may, all that we have now +to do is to consider what the school of Weismann has had to say with +regard to these experiments on the grounds of general reasoning which +they have thus far been satisfied to occupy. + + [64] For Professor Weismann's statement of and discussion of these + results see _Essays_, vol. i. p. 313. + + [65] _Oesterreichische medicinische Jahrbücher_, 1875, 179. + +In view of Obersteiner's corroboration of Brown-Séquard's results +touching the artificial production and subsequent transmission of +epilepsy, Weismann accepts the facts, but, in order to save his theory +of heredity, he argues that the transmission may be due to a traumatic +introduction of "some unknown microbe" which causes the epilepsy in the +parent, and, by invading the ova or spermatozoa as the case may be, also +produces epilepsy in the offspring. Here, of course, there would be +transmission of epilepsy, but it would not be, technically speaking, an +hereditary transmission. The case would resemble that of syphilis, where +the sexual elements remain unaffected as to their congenital endowments, +although they have been made the vehicles for conveying an organic +poison to the next generation. + +Now it would seem that this suggestion is not, on the face of it, a +probable one. For "some unknown microbe" it indeed must be, which is +always on hand to enter a guinea-pig when certain operations are being +performed on certain parts of the nervous system, but yet will never +enter when operations of any kind are being effected elsewhere. +Moreover, Westphal has produced the epilepsy _without any incision_, by +striking the heads of the animals with a hammer[66]. This latter fact, +it appears to me, entirely abolishes the intrinsically improbable +suggestion touching an unknown--and strangely eclectic--microbe. +However, it is but fair to state what Weismann himself has made of this +fact. The following is what he says:-- + + [66] _Loc. cit._ + + "It is obvious that the presence of microbes can have nothing to do + with such an attack, but the shock alone must have caused + morphological and functional changes in the centre of the pons and + medulla oblongata, identical with those produced by microbes in the + other cases.... Various stimuli might cause the nervous centres + concerned to develop the convulsive attack which, together with its + after-effects, we call epilepsy. In Westphal's case, such a + stimulus would be given by a powerful mechanical shock (viz. blows + on the head with a hammer); in Brown-Séquard's experiments, by the + penetration of microbes[67]." + + [67] _Essays_, vol. i. p. 315. + +But from this passage it would seem that Weismann has failed to notice +that in "Westphal's case," as in "Brown-Séquard's experiments," the +epilepsy was _transmitted to progeny_. That epilepsy may be produced in +guinea-pigs by a method which does not involve any cutting (i.e. +possibility of inoculation) would no doubt tend to corroborate the +suggestion of microbes being concerned in its transmission when it is +produced by cutting, _if in the former case there were no such +transmission_. But as there _is_ transmission in _both_ cases, the +facts, so far as I can see, entirely abolish the suggestion. For they +prove that even when epilepsy is produced in the parents under +circumstances which render "it obvious that the presence of microbes can +have nothing to do with such an attack," the epileptiform condition is +notwithstanding transmitted to the progeny. What, then, is gained by +retaining the intrinsically improbable hypothesis of microbes to explain +the fact of transmission "in Brown-Séquard's experiments," when this +very same fact is proved to occur without the possibility of microbes +"in Westphal's case"? + +The only other objection with regard to the seeming transmission of +traumatic epilepsy which Weismann has advanced is, that such epilepsy +may be produced by two or three very different operations--viz. division +of the sciatic nerves (one or both), an injury to the spinal cord, and a +stroke on the head. Does not this show, it is asked, that the epileptic +condition of guinea-pigs is due to a generally unstable condition of the +whole nervous system and is not associated with any particular part +thereof? Well, supposing that such is the case, what would it amount to? +I cannot see that it would in any way affect the only question in +debate--viz. What is the significance of the fact that epilepsy is +_transmitted_? Even if it be but "a tendency," "a disposition," or "a +diathesis" that is transmitted, it is none the less a case of +transmission, in fact quite as much so as if the pathological state were +dependent on the impaired condition of any particular nerve-centre. For, +it must be observed, there can be no question that it is always produced +by an operation of _some_ kind. If it were ever to originate in +guinea-pigs spontaneously, there might be some room for supposing that +its transmission is due to a congenital tendency running through the +whole species--although even then it would remain unaccountable, on the +ultra-Darwinian view, why this tendency should be congenitally +_increased_ by means of an operation. But epilepsy does not originate +spontaneously in guinea-pigs; and therefore the criticism in question +appears to me irrelevant. + +Again, it may be worth while to remark that Brown-Séquard's experiments +do not disprove the possibility of its being some one nerve-centre which +is concerned in all cases of traumatic epilepsy. And this possibility +becomes, I think, a probability in view of Luciani's recent experiments +on the dog. These show that the epileptic condition can be produced in +this animal by injury to the cortical substance of the hemispheres, and +is then transmitted to progeny[68]. These experiments, therefore, are of +great interest--first, as showing that traumatic and transmissible +epilepsy is not confined to guinea-pigs; and next, as indicating that +the pathological state in question is associated with the highest +nerve-centres, which may therefore well be affected by injury to the +lower centres, or even by section of a large nerve trunk. + + [68] _Les fonctions du Cerveau_, p. 102. + +So much, then, with regard to the case of transmitted epilepsy. But now +it must be noted that, even if Weismann's suggestion touching microbes +were fully adequate to meet this case, it would still leave unaffected +those of transmitted protrusion of the eye, drooping of the eyelid, +gangrene of the ear, absence of toes, &c. In all these cases the facts, +as stated by Brown-Séquard, are plainly unamenable to any explanation +which would suppose them due to microbes, or even to any general +neurotic condition induced by the operation. They are much too definite, +peculiar, and localized. Doubtless it is on this account that the school +of Weismann has not seriously attempted to deal with them, but merely +recommends their repetition by other physiologists[69]. Certain +criticisms, however, have been urged by Weismann against the +_interpretation_ of Brown-Séquard's facts as evidence in favour of the +transmission of acquired characters. It does not appear to me that these +criticisms present much weight; but it is only fair that we should here +briefly consider them[70]. + + [69] _Essays_, vol. i. p. 82. + + [70] As Weismann gives an excellent abstract of all the alleged + facts up to date (_Essays_, vol. i. pp. 319-324), it is + needless for me to supply another, further than that which I + have already made from Brown-Séquard. + +First, with regard to Brown-Séquard's results other than the production +of transmitted epilepsy, Weismann allows that the hypothesis of microbes +can scarcely apply. In order to meet these results, therefore, he +furnishes another suggestion--viz. that where the nervous system has +sustained "a great shock," the animals are very likely to bear "weak +descendants, and such as are readily affected by disease." Then, in +answer to the obvious consideration, "that this does not explain why the +offspring should suffer from the same disease" as that which has been +produced in the parents, he adds--"But this does not appear to have been +by any means invariably the case. For 'Brown-Séquard himself says, the +changes in the eye of the offspring were of a very variable nature, and +were only occasionally exactly similar to those observed in the +parents.'" + +Now, this does not appear to me a good commentary. In the first place, +it does not apply to the other cases (such as the ears and the toes), +where the changes in the offspring, when they occurred at all, _were_ +exactly similar to those observed in the parents, save that some of them +occasionally occurred on the _opposite_ side, and frequently also on +_both_ sides of the offspring. These subordinate facts, however, will +not be regarded by any physiologist as making against the more ready +interpretation of the results as due to heredity. For a physiologist +well knows that homologous parts are apt to exhibit correlated +variability--and this especially where variations of a congenital kind +are concerned, and also where there is any reason to suppose that the +nervous system is involved. Moreover, even in the case of the eye, it +was always protrusion that was caused in the parent and transmitted to +the offspring as a result of injuring the restiform bodies of the +former; while it was always partial closure of the eyelids that was +caused and transmitted by section of the sympathetic nerve, or removal +of the cervical ganglia. Therefore, if we call such effects "diseases," +surely it _was_ "the same disease" which in each case appeared in the +parents and reappeared in their offspring. Again, the "diseases" were so +peculiar, definite, and localized, that I cannot see how they can be +reasonably ascribed to a general nervous "shock." Why, for instance, if +this were the case, should a protruding eye never result from removal +of the cervical ganglia, a drooping eyelid from a puncture of the +restiform body, a toeless foot from either or both of these operations, +and so on? In view of such considerations I cannot deem these +suggestions touching "microbes" and "diseases" as worthy of the +distinguished biologist from whom they emanate. + +Secondly, Weismann asks--How can we suppose these results to be +instances of the transmission of acquired characters, when from +Brown-Séquard's own statement of them it appears that the mutilation +itself was not inherited, but only its effects? Neither in the case of +the sciatic nerve, the sympathetic nerve, the cervical ganglion, nor the +restiform bodies, was there ever any trace of transmitted injury in the +corresponding parts of the offspring; so that, if the "diseases" from +which they suffered be regarded as hereditary, we have to suppose that a +consequence was in each case transmitted without the transmission of its +cause, which is absurd. But I do not think that this criticism can be +deemed of much weight by a physiologist as distinguished from a +naturalist. For nothing is more certain to a student of physiology, in +any of its branches, than that negative evidence, if yielded by the +microscope alone, is most precarious. Therefore it does not need a +_visible_ change in the nervous system to be present, in order that the +part affected should be functionally weak or incapable: pathology can +show numberless cases of nerve-disorder the "structural" causes of which +neither the scalpel nor the microscope can detect. So that, if any +peculiar form of nerve-disorder is transmitted to progeny, and if it be +certain that it has been caused by injury to some particular part of +the nervous system, I cannot see that there is any reason to doubt the +transmission of a nervous lesion merely on the ground that it is not +visibly discernible. Of course there may be other grounds for doubting +it; but I am satisfied that this ground is untenable. Besides, it must +be remembered, as regards the particular cases in question, that no one +has thus far investigated the histology of the matter by the greatly +improved methods which are now at our disposal. + + * * * * * + +I have now considered all the criticisms which have been advanced +against what may be called the Lamarckian interpretation of +Brown-Séquard's results; and I think it will be seen that they present +very little force--even if it can be seen that they present any force at +all. But it must be remembered that this is a different thing from +saying that the Lamarckian interpretation is the true one. The facts +alleged are, without question, highly peculiar; and, on this account +alone, Brown-Séquard's interpretation of them ought to be deemed +provisional. Hence, although as yet they have not encountered any valid +criticism from the side of ultra-Darwinian theory, I do not agree with +Darwin that, on the supposition of their truth as facts, they furnish +positive proof of the transmission of acquired characters. Rather do I +agree with Weismann that further investigation is needed in order to +establish such an important conclusion on the basis of so unusual a +class of facts. This further investigation, therefore, I have +undertaken, and will now state the results. + +Although this work was begun over twenty years ago, and then yielded +negative results, it was only within the last decade that I resumed it +more systematically, and under the tutelage of Brown-Séquard himself. +During the last two years, however, the experiments have been so much +interrupted by illness that even now the research is far from complete. +Therefore I will here confine myself to a tabular statement of the +results as far as they have hitherto gone, on the understanding that, in +so far as they are negative or doubtful, I am not yet prepared to +announce them as final. + +We may take Brown-Séquard's propositions in his own order, as already +given on page 104. + + 1st. Appearance of epilepsy in animals born of parents which had + been rendered epileptic by an injury to the spinal cord. + + 2nd. Appearance of epilepsy also in animals born of parents which + had been rendered epileptic by section of the sciatic nerve. + +I did not repeat these experiments with a view to producing epilepsy, +because, as above stated, they had been already and sufficiently +corroborated in this respect. But I repeated many times the experiments +of dividing the sciatic nerve for the purpose of testing the statements +made later on in paragraphs 7 and 8, and observed that it almost always +had the effect of producing epilepsy in the animal thus operated +upon--and this of a peculiar kind, the chief characteristics of which +may here be summarized. The epileptiform habit does not supervene until +some considerable time after the operation; it is then transitory, +lasting only for some weeks or months. While the habit endures the fits +never occur spontaneously, but only as a result of irritating a small +area of skin behind the ear on the same side of the body as that on +which the sciatic nerve had been divided. Effectual irritation may be +either mechanical (such as gentle pinching), electrical, or, though less +certainly, thermal. The area of skin in question, soon after the +epileptiform habit supervenes, and during all the time that it lasts, +swarms with lice of the kind which infest guinea-pigs--i.e. the lice +congregate in this area, on account, I think, of the animal being there +insensitive, and therefore not disturbing its parasites in that +particular spot; otherwise it would presumably throw itself into fits by +scratching that spot. On removing the skin from the area in question, no +kind or degree of irritation supplied to the subjacent tissue has any +effect in producing a fit. A fit never lasts for more than a very few +minutes, during which the animal is unconscious and convulsed, though +not with any great violence. The epileptiform habit is but rarely +transmitted to progeny. Most of these observations are in accordance +with those previously made by Brown-Séquard, and also by others who have +repeated his experiments under this heading. I can have no doubt that +the injury of the sciatic nerve or spinal cord produces a change in some +of the cerebral centres, and that it is this change--whatever it is and +in whatever part of the brain it takes place--which causes the +remarkable phenomena in question. + + 3rd. A change in the shape of the ear in animals born of parents in + which such a change was the effect of a division of the cervical + sympathetic nerve. + + 4th. Partial closure of the eyelids in animals born of parents in + which that state of the eyelids had been caused either by section + of the cervical sympathetic nerve, or the removal of the superior + cervical ganglion. + +I have not succeeded in corroborating these results. It must be added, +however, that up to the time of going to press my experiments on this, +the easiest branch of the research, have been too few fairly to prove a +negative. + + 5th. Exophthalmia in animals born of parents in which an injury to + the restiform body had produced that protrusion of the eyeball.... + In these animals, modified by heredity, the two eyes generally + protruded, although in the parents usually only one showed + exophthalmia, the lesion having been made in most cases only on one + of the corpora restiformia. + +I have fully corroborated the statement that injury to a particular spot +of the restiform body is quickly followed by a marked protrusion of the +eyeball on the same side. I have also had many cases in which some of +the progeny of parents thus affected have shown considerable protrusion +of the eyeballs on both sides, and this seemingly abnormal protrusion +has been occasionally transmitted to the next generation. Nevertheless, +I am far from satisfied that this latter fact is anything more than an +accidental coincidence. For I have never seen the so-called exophthalmia +of progeny exhibited in so high a degree as it occurs in the parents as +an immediate result of the operation, while, on examining any large +stock of normal guinea-pigs, there is found a considerable amount of +individual variation in regard to prominence of eyeballs. Therefore, +while not denying that the obviously abnormal amount of protrusion due +to the operation may be inherited in lesser degrees, and thus may be the +cause of the unusual degree of prominence which is sometimes seen in the +eyeballs of progeny born of exophthalmic parents, I am unable to affirm +so important a conclusion on the basis supplied by these experiments. + + 6th. Haematoma and dry gangrene of the ears in animals born of + parents in which these ear-alterations had been caused by an injury + to the restiform body. + +As regards the animals operated upon (i. e. the parents), I find that +the haematoma and dry gangrene may supervene either several weeks after +the operation, or at any subsequent time up to many months. When it does +supervene it usually affects the upper parts of both ears, and may then +eat its way down until, in extreme cases, it has entirely consumed +two-thirds of the tissue of both ears. As regards the progeny of animals +thus affected, in some cases, but by no means in all, a similarly morbid +state of the ears may arise apparently at any time in the life-history +of the individual. But I have observed that in cases where two or more +individuals _of the same litter_ develop this diseased condition, they +usually do so at about the same time--even though this be many months +after birth, and therefore after the animals are fully grown. But in +progeny the morbid process never goes so far as in the parents which +have been operated upon, and it almost always affects the _middle_ +thirds of the ears. In order to illustrate these points, reproductions +of two of my photographs are appended. They represent the consequences +of the operation on a male and a female guinea-pig. Among the progeny of +both these animals there were several in which a portion of each ear was +consumed by apparently the same process, where, of course, there had +been no operation. + +[Illustration: FIG. 1.--Reproduction of photographs from life of a male +and female guinea-pig, whose left restiform bodies had been injured by a +scalpel six months previously. The loss of tissue in both ears was due +to haematoma and dry gangrene, which, however, had ceased when the +photograph was taken.] + +It should be observed that not only is a different _part_ of the ear +affected in the progeny, but also a very much less _quantity_ thereof. +Naturally, therefore, the hypothesis of heredity seems less probable +than that of mere coincidence on the one hand, or of transmitted +microbes on the other. But I hope to have fairly excluded both these +alternative explanations. For, as regards merely accidental coincidence, +I have never seen this very peculiar morbid process in the ears, or in +any other parts, of guinea-pigs which have neither themselves had their +restiform bodies injured, nor been born of parents thus mutilated. As +regards the hypothesis of microbes, I have tried to inoculate the +corresponding parts of the ears of normal guinea-pigs, by first +scarifying those parts and then rubbing them with the diseased surfaces +of the ears of mutilated guinea-pigs; but have not been able in this way +to communicate the disease. + +It will be seen that the above results in large measure corroborate the +statements of Brown-Séquard; and it is only fair to add that he told me +they are the results which he had himself obtained most frequently, but +that he had also met with many cases where the diseased condition of the +ears in parents affected the same parts in their progeny, and also +occurred in more equal degrees. Lastly, I should like to remark, with +regard to these experiments on restiform bodies, and for the benefit of +any one else who may hereafter repeat them, that it will be necessary +for him to obtain precise information touching the _modus operandi_. For +it is only one very localized spot in each restiform body which has to +be injured in order to produce any of the results in question. I myself +lost two years of work on account of not knowing this exact spot before +going to Paris for the purpose of seeing Brown-Séquard himself perform +the operation. I had in the preceding year seen one of his assistants do +so, but this gentleman had a much more careless method, and one which in +my hands yielded uniformly negative results. The exact spot in question +in the restiform body is as far forwards as it is possible to reach, and +as far down in depth as is compatible with not producing rotatory +movements. + + 7th. Absence of two toes out of the three of the hind leg, and + sometimes of the three, in animals whose parents had eaten up their + hind-leg toes which had become anaesthetic from a section of the + sciatic nerve alone, or of that nerve and also of the crural. + Sometimes, instead of complete absence of the toes, only a part of + one or two or three was missing in the young, although in the + parent not only the toes but the whole foot were absent. + +As I found that the results here described were usually given by +division of the sciatic nerve alone--or, more correctly, by excision of +a considerable portion of the nerve, in order to prevent regeneration--I +did not also divide the crural. But, although I have bred numerous +litters from parents thus injured, there has been no case of any +inherited deficiency of toes. My experiments in this connexion were +carried on through a series of six successive generations, so as to +produce, if possible, a cumulative effect. Nevertheless, no effect of +any kind was produced. On the other hand, Brown-Séquard informed me that +he had observed this inherited absence of toes only in about one or two +per cent. of cases. Hence it is possible enough, that my experiments +have not been sufficiently numerous to furnish a case. It may be added +that there is here no measurable possibility of accidental coincidence +(seeing that normal guinea-pigs do not seem ever to produce young with +any deficiency of toes), while the only possibility of mal-observation +consists in some error with regard to the isolation (or the tabulation) +of parents and progeny. Such an error, however, may easily arise. For +gangrene of the toes does not set in till some considerable time after +division of the sciatic nerve. Hence, if the wound be healed before the +gangrene begins, and if any mistake has been made with regard to the +isolation (or tabulation) of the animal, it becomes possible that the +latter should be recorded as an uninjured, instead of an injured, +individual. On this account one would like to be assured that +Brown-Séquard took the precaution of examining the state of the sciatic +nerve in those comparatively few specimens which he alleges to have +displayed such exceedingly definite proof of the inheritance of a +mutilation. For it is needless to remark, after what has been said in +the preceding chapter on the analogous case of epilepsy, that the proof +would not be regarded by any physiologist as displaced by the fact that +there is no observable deficiency in the sciatic nerve of the toeless +young. + + 8th. Appearance of various morbid states of the skin and hair of + the neck and face in animals born of parents having had similar + alterations in the same parts, as effects of an injury to the + sciatic nerve. + +I have not paid any attention to this paragraph, because the facts which +it alleges did not seem of a sufficiently definite character to serve as +a guide to further experiment. + +On the whole, then, as regards Brown-Séquard's experiments, it will be +seen that I have not been able to furnish any approach to a full +corroboration. But I must repeat that my own experiments have not as yet +been sufficiently numerous to justify me in repudiating those of his +statements which I have not been able to verify. + +The only other experimental results, where animals are concerned, which +seemed to tell on the side of Lamarckianism, are those of Mr. +Cunningham, already alluded to. But, as the research is still in +progress, the school of Weismann may fairly say that it would be +premature to discuss its theoretical bearings. + + * * * * * + +Passing now from experiments on animals to experiments on plants, I must +again ask it to be borne in mind, that here also no researches have been +published, which have had for their object the testing of the question +on which we are engaged. As in the case of animals, therefore, so in +that of plants, we are dependent for any experimental results bearing +upon the subject to such as have been gained incidentally during the +course of investigations in quite other directions. + +Allusion has already been made, in my previous essay, to De Vries' +observations on the chromatophores of algae passing from the ovum of the +mother to the daughter organism; and we have seen that even Weismann +admits, "It appears possible that a transmission of somatogenetic +variation has here occurred[71]." It will now be my object to show that +such variations appear to be sometimes transmitted in the case of +higher plants, and this under circumstances which carry much less +equivocal evidence of the inheritance of acquired characters, than can +be rendered by the much more simple organization of an alga. + + [71] _Examination of Weismannism_, p. 83. + +I have previously mentioned Hoffmann's experiments on transplantation, +the result of which was to show that variations, directly induced by +changed conditions of life, were reproduced by seed[72]. Weismann, +however, as we have seen, questions the _somatogenetic_ origin of these +variations--attributing the facts to a _blastogenetic_ change produced +in the plants by a direct action of the changed conditions upon the +germ-plasm itself[73]. And he points out that whether he is right or +wrong in this interpretation can only be settled by ascertaining whether +the observable somatic changes occur in the generation which is first +exposed to the changed conditions of life. If they do occur in the first +generation, they are somatogenetic changes, which afterwards react on +the substance of heredity, so as to transmit the acquired peculiarities +to progeny. But if they do not occur till the second (or any later) +generation, they are presumably blastogenetic. Unfortunately Hoffmann +does not appear to have attended to this point with sufficient care, but +there are other experiments of the same kind where the point has been +specially observed. + + [72] _Examination of Wiesmannism_, p. 93. + + [73] _Ibid._ p. 153. + +For instance, M. L. A. Carrière[74] gathered seed from the wild radish +(_Raphanus Raphanistrum_) in France, and sowed one lot in the light dry +soil near the Museum of Natural History in Paris, while another lot was +sown by him at the same time in heavy soil elsewhere. His object was to +ascertain whether he could produce a good cultivated radish by +methodical selection; and this he did; in a wonderfully rapid manner, +during the course of a very few generations. But the point for us is, +that _from the first_ the plants grown in the light soil of Paris +presented sundry marked differences from those grown in the heavy soil +of the country; and that these points of difference had nothing to do +with the variations on which his artificial selection was brought to +bear. For while his artificial selection was directed to increasing the +_size_ of the "root," the differences in question had reference to its +_form_ and _colour_. In Paris an elongated form prevailed, which +presented either a white or a rose colour: in the country the form was +more rounded, and the colour violet, dark brown, or "almost black." Now, +as these differences were strongly apparent in the first generation, and +were not afterwards made the subject of selection, both in origin and +development they must have been due to "climatic" influences acting on +the somatic tissues. And although the author does not appear to have +tested their hereditary characters by afterwards sowing the seed from +the Paris variety in the country, or _vice versa_, we may fairly +conclude that these changes must have been hereditary--1st, from the +fact of their intensification in the course of the five sequent +generations over which the experiment extended, and, 2nd, from the very +analogous results which were similarly obtained in the following case +with another genus, where both the somatogenetic and the hereditary +characters of the change were carefully and specially observed. This +case is as follows. + + [74] _Origine des Plantes Domestiques, démontrée par la culture du + Radis Sauvage_ (Paris, 1869). + +The late Professor James Buckman, F.R.S., saved some seed from wild +parsnips (_P. sativa_) in the summer of 1847, and sowed under changed +conditions of life in the spring of 1848. The plants grown from these +wild seeds were for the most part like wild plants; but some of them had +"already (i.e. in the autumn of 1848) the light green and smooth aspect +devoid of hairs which is peculiar to the cultivated plant; and among the +latter there were a few with longer leaves and broader divisions of +leaf-lobes than the rest--the leaves, too, all growing systematically +round one central bud. The roots of the plant when taken up were +observed to be for the most part more fleshy than those of wild +examples[75]." + + [75] _Journl. Agric. Soc._ 1848. + +Professor Buckman then proceeds to describe how he selected the best +samples for cultivation in succeeding generations, till eventually the +variety which he called "The Student" was produced, and which Messrs. +Sutton still regard as the best variety in their catalogue. That is to +say, it has come true to seed for the last forty years; and although +such great excellence and stability are doubtless in chief part due to +the subsequent process of selection by Professor Buckman in the years +1848-1850, this does not affect the point with which we are here +concerned--namely, that the somatogenetic changes of the plants in the +first generation were transmitted by seed to the second generation, and +thus furnished Professor Buckman with the material for his subsequent +process of selection. And the changes in question were not merely of a +very definite character, but also of what may be termed a very _local_ +character--affecting only particular tissues of the soma, and therefore +expressive of a high degree of _representation_ on the part of the +subsequently developed seed, by which they were faithfully reproduced in +the next generation. + +Here is another case. M. Lesage examined the tissues of a large number +of plants growing both near to, and remote from, the sea. He suspected +that the characteristic fleshiness, &c. of seaside plants was due to the +influence of sea-salt; and proved that such was the case by causing the +characters to occur in inland plants as a result of watering them with +salt-water. Then he adds:-- + + "J'ai réussi surtout pour le _Lepidium sativum_ cultivé en 1888; + j'ai obtenu pour la même plante des résultats plus nets encore dans + la culture de 1889, entreprise en semant les graines récoltées avec + soin des pots de l'année précédente et traitées exactement de la + même façon[76]." + + [76] _Rev. Gén. de Bot._ tom. ii. p. 64. + +Here, it will be observed, there was no selection; and therefore the +increased hereditary effect in the second generation must apparently be +ascribed to a continuance of influence exercised by somatic tissues on +germinal elements; for at the time when the changes were produced no +seed had been formed. In other words, the accumulated change, like the +initial change, would seem to have been exclusively of somatogenetic +origin; and yet it so influenced the qualities of the seed (as this was +afterwards formed), that the augmented changes were transmitted to the +next generation, part for part, as the lesser changes had occurred in +the preceding generation. "This experiment, therefore, like Professor +Buckman's, shows that the alteration of the tissues was carried on in +the second generation from the point gained in the first. In both cases +no germ-plasm (in the germ-cells) existed at the time during which the +alterations arose, as they were confined to the vegetative system; and +in the case of the parsnips and carrots, being biennials no germ-cells +are produced till the second year has arrived[77]." + + [77] I am indebted to the Rev. G. Henslow for the references to + these cases. This and the passages which follow are quoted from + his letters to me. + +Once more, Professor Bailey remarks:-- + + "Squashes often show remarkable differences when grown upon + different soils; and these differences can sometimes be perpetuated + for a time by seeds. The writer has produced, from the same parent, + squashes so dissimilar, through the simple agency of a change of + soil in one season, that they might readily be taken for distinct + varieties. Peas are known to vary in the same manner. The seeds of + a row of peas of the same kind, last year gave the writer marked + variations due to differences of soil.... Pea-growers characterize + soils as 'good' and 'viney.' Upon the latter sort the plants run to + vine at the expense of the fruit, and their offspring for two or + three generations have the same tendency[78]." + + [78] _Gardener's Chronicle_, May 31, 1890, p. 677. + +I think these several cases are enough to show that, while the +Weismannian assumption as to the seeming transmission of somatogenetic +characters being restricted to the lowest kinds of plants is purely +gratuitous, there is no small amount of evidence to the contrary--or +evidence which seems to prove that a similar transmission occurs +likewise in the higher plants. And no doubt many additional cases might +be advanced by any one who is well read in the literature of economic +botany. + +It appears to me that the only answer to such cases would be furnished +by supposing that the hereditary changes are due to an alteration of the +residual "germ-plasm" in the wild seed, when this is first exposed to +the changed conditions of life, due to its growth in a strange kind of +soil--e.g. while germinating in an unusual kind of earth for producing +the first generation. But this would be going a long way to save an +hypothesis. In case, however, it should now be suggested, I may remark +that it would be negatived by the following facts.[79] + + [79] Since the above was written Professor Weismann has advanced, in + _The Germ-plasm_, a suggestion very similar to this. It is + sufficient here to remark, that nearly all the facts and + considerations which ensue in the present chapter are + applicable to his suggestion, the essence of which is + anticipated in the above paragraph. + +In the first place, an endless number of cases might be quoted where +somatogenetic changes thus produced by changed conditions of life are +not hereditary. Therefore, in all these cases it is certainly not the +"germ-plasm" that is affected. In other words, there can be no question +that somatogenetic changes of the kinds above mentioned do very readily +admit of being produced in the first generation by changes of soil, +altitude, &c. And that somatogenetic changes thus produced should not +always--or even generally--prove themselves to be hereditary from the +first moment of their occurrence, is no more than any theory of +heredity would expect. Indeed, looking to the known potency of +reversion, the wonder is that in any case such changes should become +hereditary in a single generation. On the other hand, there is no reason +to imagine that the hypothetical germ-plasm--howsoever _unstable_ we may +suppose it to be--can admit of being directly affected by a change of +soil in a single generation. For, on this view, it must presumably be +chiefly affected during the short time that the seed is germinating; and +during that time the changed conditions can scarcely be conceived as +having any points of attack, so to speak, upon the residual germ-plasm. +There are no roots on which the change of _soil_ can make itself +perceptible, nor any stem and leaves on which the change of _atmosphere_ +can operate. Yet the changed condition's may produce hereditary +modifications in any parts of the plant, which are not only precisely +analogous to non-hereditary changes similarly produced in the somatic +tissues of innumerable other plants, but are always of precisely the +same kind in the same lot of plants that are affected. When all the +radishes grown from wild seed in Paris, for instance, varied in the +direction of rotundity and dark colour, while those grown in the country +presented the opposite characters, we can well understand the facts as +due to an entire season's action upon the whole of the growing plant, +with the result that all the changes produced in each set of plants were +similar--just as in the cases where similarly "climatic" modifications +are not hereditary, and therefore unquestionably due to changed +conditions acting on roots, stems, leaves, or flowers, as the case may +be. On the other hand, it is not thus intelligible that during the +short time of germination the changed conditions should effect a +re-shuffling (or any other modification) of the "germ-plasm" in the +seeds--and this in such a manner that the effect on the residual +germ-plasm reserved for future generations is precisely similar to that +produced on the somatic tissues of the developing embryo. + +In the second place, as we have seen, in some of the foregoing cases the +changes were produced months--and even years--before the seeds of the +first germination were formed. Therefore the hereditary effect, if +subsequent to the period of embryonic germination, must have been +produced on germ-plasm as this occurs diffused through the somatic +tissues. But, if so, we shall have to suppose that such germ-plasm is +afterwards gathered in the seeds when these are subsequently formed. +This supposition, however, would be radically opposed to Weismann's +theory of heredity: nor do I know of any other theory with which it +would be reconcilable, save such as entertain the possibility of the +Lamarckian factors. + +Lastly, in the third place, I deem the following considerations of the +highest importance:-- + + "As other instances in which peculiar structures are now hereditary + may be mentioned aquatic plants and those producing subterraneous + stems. Whether they be dicotyledons or monocotyledons, there is a + fundamental agreement in the anatomy of the roots and stem of + aquatic plants, and, in many cases, of the leaves as well. Such has + hitherto been attributed to the aquatic habit. The inference or + deduction was, of course, based upon innumerable coincidences; the + water being supposed to be the direct cause of the degenerate + structures, which are hereditary and characteristic of such plants + in the wild state. M. Costantin has, however, verified this + deduction, by making terrestrial and aerial stems to grow + underground and in water: the structures _at once_ began to assume + the subterranean or aquatic type, as the case might be; and, + conversely, aquatic plants made to grow upon land _at once_ began + to assume the terrestrial type of structure, while analogous + results followed changes from a subterranean to an aerial position, + and _vice versa_." + +This is also quoted from the Rev. Prof. Henslow's letters to me, and the +important point in it is, that the great changes in question are proved +to be of a purely "somatogenetic" kind; for they occurred "at once" _in +the ready-grown plant_, when the organs concerned were exposed to the +change from aquatic to terrestrial life, or _vice versa_--and also from +a subterranean to an aerial position, or _vice versa_. Consequently, +even the abstract possibility of the changed conditions of life having +operated on the _seed_ is here excluded. Yet the changes are of +precisely the same kind as are now _hereditary_ in the wild species. It +thus appears undeniable that all these remarkable and uniform changes +must originally have been somatogenetic changes; yet they have now +become blastogenetic. This much, I say, seems undeniable; and therefore +it goes a long way to prove that the non-blastogenetic character of the +changes has been due to their originally somatogenetic character. For, +if not, how did natural selection ever get an opportunity of making any +of them blastogenetic, when every individual plant has always presented +them as already given somatogenetically? This last consideration appears +in no small measure to justify the opinion of Mr. Henslow, who +concludes--"These experiments prove, not only that the influence of the +environment is _at once_ felt by the organ; but that it is indubitably +the _cause_ of the now specific and hereditary traits peculiar to +normally aquatic, subterranean, and aerial stems, or roots[80]." + + [80] It also serves to show that Weismann's newer doctrine of + similar "determinants" occurring both in the germ and in the + somatic tissues is a doctrine which cannot be applied to rebut + this evidence of the transmission of acquired characters in + plants. Therefore even its hypothetical validity as applied by + him to explain the seasonal variation of butterflies is + rendered in a high degree dubious. + +He continues to furnish other instances in the same line of proof--such +as the distinctive "habits" of insectivorous, parasitic, and climbing +plants; the difference in structure between the upper and under sides of +horizontal leaves, &c. "For here, as in all organs, we discover by +experiment how easily the anatomy of plants can be affected by their +environment; and that, as long as the latter is constant, so are the +characters of the plants constant and hereditary." + + [The following letter, contributed by Dr. Hill to _Nature_, vol. I. + p. 617, may here be quoted. C. Ll. M. + + "It may be of interest to your readers to know that two guinea-pigs + were born at Oxford a day or two before the death Dr. Romanes, both + of which exhibited a well-marked droop of the left upper eyelid. + These guinea-pigs were the offspring of a male and a female + guinea-pig in both of which I had produced for Dr. Romanes, some + months earlier, a droop of the left upper eyelid by division of the + left cervical sympathetic nerve. This result is a corroboration of + the series of Brown-Séquard's experiments on the inheritance of + acquired characteristics. A very large series of such experiments + are of course needed to eliminate all sources of error, but this I + unfortunately cannot carry out at present, owing to the need of a + special farm in the country, for the proper care and breeding of + the animals.--LEONARD HILL. + + "Physiological Laboratory, Univ. Coll. London, Oct. 18, 1894."] + + + + +CHAPTER V. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(A. and B.) + + +_Direct and Indirect Evidence in favour of the Non-inheritance of +Acquired Characters_[81]. + + [81] [_See_ note appended to Preface. C. LI. M.] + +The strongest argument in favour of "continuity" is that based upon the +immense difference between congenital and acquired characters in respect +of heritability. For that there is a great difference in this respect is +a matter of undeniable fact. And it is obvious that this difference, the +importance of which must be allowed its full weight, is just what we +should expect on the theory of the continuity of the germ-plasm, as +opposed to that of pangenesis. Indeed it may be said that the difference +in question, while it constitutes important _evidence_ in favour of the +former theory, is a _difficulty_ in the way of the latter. But here two +or three considerations must be borne in mind. + +In the first place, this fact has long been one which has met with wide +recognition and now constitutes the main ground on which the theory of +continuity stands. That is to say, it was the previous knowledge of +this contrast between congenital and acquired characters which led to +the formulation of a theory of continuity by Mr. Galton, and to its +subsequent development by Prof Weismann. + +But, in the second place, there is a wide difference between the +certainty of this fact and that of the theory based upon it. The certain +fact is, that a great distinction in respect of heritability is +observable between congenital and acquired characters. The theory, as +formulated by Weismann, is that the distinction is not only great but +absolute, or, in other words, that in no case and in no degree can any +acquired character be ever inherited. This hypothesis, it will be +observed, goes far beyond the observed fact, for it is obviously +possible that, notwithstanding this great difference in regard to +heritability between congenital and acquired characters, the latter may +nevertheless, sometimes and in some degree, be inherited, however much +difficulty we may experience in observing these lesser phenomena in +presence of the greater. The Weismannian hypothesis of _absolute_ +continuity is one thing, while the observed fact of at least a _high +relative degree_ of continuity is quite another thing. And it is +necessary to be emphatic on this point, since some of the reviewers of +my _Examination of Weismannism_ confound these two things. Being +apparently under the impression that it was reserved for Weismann to +perceive the fact of there being a great difference between the +heritability of congenital and acquired characters, they deem it +inconsistent in me to acknowledge this fact while at the same time +questioning the hypothetical basis of his fundamental postulate touching +the absolute continuity of germ-plasm. It is one merit of Galton's +theory, as against Weismann's, that it does not dogmatically exclude the +possible interruption of continuity on some occasions and in some +degree. Herein, indeed, would seem to lie the central core of the whole +question in dispute. For it is certain and has long been known that +individually acquired characters are at all events much less heritable +than are long-inherited or congenital ones. But Lamarckian theory +supposes that congenital characters were in some cases originally +acquired, and that what are now blastogenetic characters were in some +cases at first somatogenetic and have become blastogenetic only in +virtue of sufficiently long inheritance. Since Darwin's time, however, +evolutionists (even of the so-called Lamarckian type) have supposed that +natural selection greatly assists this process of determining which +somatogenetic characters shall become congenital or blastogenetic. Hence +all schools of evolutionists are, and have long been, agreed in +regarding the continuity principle as true in the main. No evolutionist +would at any time have propounded the view that one generation depends +for _all_ its characters on those acquired by its _immediate_ ancestors, +for this would merely be to unsay the theory of Evolution itself, as +well as to deny the patent facts of heredity as shown, for example, in +atavism. At most only some fraction of a _per cent._ could be supposed +to do so. But Weismann's contention is that this principle is not only +true in the main, but _absolutely_ true; so that natural selection +becomes all in all or not at all. Unless Weismannism be regarded as +this doctrine of absolutism it permits no basis for his attempted theory +of evolution. + +And, whatever may be said to the contrary by the more enthusiastic +followers of Prof. Weismann, I must insist that there is the widest +possible difference between the truly scientific question of fact which +is assumed by Weismann as answered (the base-line of the diagram on p. +43), and the elaborate structure of deductive reasoning which he has +reared on this assumption (the Y-like structure). Even if the assumption +should ever admit of inductive proof, the almost bewildering edifice of +deductive reasoning which he has built upon it would still appear to me +to present extremely little value of a scientific kind. Interesting +though it may be as a monument of ingenious speculation hitherto unique +in the history of science, the mere flimsiness of its material must +always prevent its far-reaching conclusions from being worthy of serious +attention from a biological point of view. But having already attempted +to show fully in my _Examination_ this great distinction between the +scientific importance of the question which lies at the base of +"Weismannism," and that of the system which he has constructed on his +assumed answer thereto, I need not now say anything further with regard +to it. + +Again, on the present occasion and in this connexion I should like to +dissipate a misunderstanding into which some of the reviewers of the +work just mentioned have fallen. They appear to have concluded that +because I have criticized unfavourably a considerable number of +Weismann's theories, I have shown myself hostile to his entire system. +Such, however, is by no means the case; and the misunderstanding can +only be accounted for by supposing that the strongly partisan spirit +which these critics display on the side of neo-Darwinism has rendered +them incapable of appreciating any attempt at impartial--or even so much +as independent--criticism. At all events, it is a matter of fact that +throughout the work in question I have been particularly careful to +avoid this misunderstanding as to my own position. Over and over again +it is there stated that, far from having any objection to the principle +of "Continuity" as represented in the base-line of the above diagram, I +have been convinced of its truth ever since reading Mr. Galton's _Theory +of Heredity_ in 1875. All the "hard words" which I have written against +Weismann's system of theories have reference to those parts of it which +go to constitute the Y-like structure of the diagram. + +It is, however, desirable to recur to another point, and one which I +hope will be borne in mind throughout the following discussion. It has +already been stated, a few pages back, that the doctrine of continuity +admits of being held in two very different significations. It may be +held as absolute, or as relative. In the former case we have the +Weismannian doctrine of germ-plasm: the substance of heredity is taken +to be a substance _per se_, which has always occupied a separate +"sphere" of its own, without any contact with that of somatoplasm +further than is required for its lodgement and nutrition; hence it can +never have been in any degree modified as to its hereditary qualities by +use-inheritance or any other kind of somatogenetic change; it has been +_absolutely_ continuous "since the first origin of life." On the other +hand, the doctrine of continuity may be held in the widely different +sense in which it has been presented by Galton's theory of Stirp. Here +the doctrine is, that while for the most part the phenomena of heredity +are due to the continuity of the substance of heredity through +numberless generations, this substance ("Stirp") is nevertheless not +absolutely continuous, but may admit, in small though cumulative +degrees, of modification by use-inheritance and other factors of the +Lamarckian kind. Now this all-important distinction between these two +theories of continuity has been fully explained and thoroughly discussed +in my _Examination_; therefore I will not here repeat myself further +than to make the following remarks. + +The Weismannian doctrine of continuity as absolute (base-line of the +diagram) is necessary for the vast edifice of theories which he has +raised upon it (the Y), first as to the minute nature and exact +composition of the substance of heredity itself ("Germ-plasm"), next as +to the precise mechanism of its action in producing the visible +phenomena of heredity, variation, and all allied phenomena, and, lastly, +the elaborate and ever-changing theory of organic evolution which is +either founded on or interwoven with this vast system of hypothetic +speculation. Galton's doctrine of continuity, on the other hand, is a +"Theory of Heredity," and a theory of heredity alone. It does not meddle +with any other matters whatsoever, and rigidly avoids all speculation +further than is necessary for the bare statement and inductive support +of the doctrine in question. Hence, it would appear that this, the only +important respect wherein the doctrine of continuity as held by Galton +differs from the doctrine as held by Weismann, arisen from the necessity +under which the latter finds himself of postulating _absolute_ +continuity as a logical basis for his deductive theory of the precise +mechanism of heredity on the one hand, and of his similarly deductive +theory of evolution on the other. So far as the doctrine of continuity +is itself concerned (i.e. the question of the inheritance of acquired +characters), there is certainly no more inductive reason for supposing +the continuity absolute "since the first origin of life," than there is +for supposing it to be more or less susceptible of interruption by the +Lamarckian factors. In other words, but for the sake of constructing a +speculative foundation for the support of his further theories as to +"the architecture of germ-plasm" and the factors of organic evolution, +there is no reason why Weismann should maintain the absolute separation +of the "sphere" of germ-plasm from that of somatoplasm. On the contrary, +he has no reason for concluding against even a considerable and a +frequent amount of cutting, or overlapping, on the part of these two +spheres. + +But although this seems to me sufficiently obvious, as I have shown at +greater length in the _Examination of Weismannism_, it must not be +understood that I hold that there is room for any large amount of such +overlapping. On the contrary, it appears to me as certain as anything +can well be that the amount of such overlapping from one generation to +another, if it ever occur at all, must be exceedingly small, so that, +if we have regard to only a few sequent generations, the effects of +use-inheritance, and Lamarckian factors are, at all events as a rule, +demonstrably imperceptible. But this fact does not constitute any +evidence--as Weismann and his followers seem to suppose--against a +possibly important influence being exercised by the Lamarckian factors, +in the way of gradual increments through a long series of generations. +It has long been well known that acquired characters are at best far +less fully and far less certainly inherited than are congenital ones. +And this fact is of itself sufficient to prove the doctrine of +continuity to the extent that even the Lamarckian is rationally bound to +concede. But the fact yields no proof--scarcely indeed so much as a +presumption--in favour of the doctrine of continuity as absolute. For it +is sufficiently obvious that the adaptive work of heredity could not be +carried on at all if there had to be a discontinuity in the substance of +heredity at every generation, or even after any very large number of +generations. + +Little more need be said concerning the arguments which fall under the +headings A and B. The Indirect evidence is considered in Appendix I of +the _Examination of Weismannism_; while the Direct evidence is +considered in the text of that work in treating of Professor Weismann's +researches on the _Hydromedusae_ (pp. 71-76). + +The facts of karyokinesis are generally claimed by the school of +Weismann as making exclusively in favour of continuity as absolute. But +this is a partisan view to take. In any impartial survey it should be +seen that while the facts are fairly interpretable on Weismann's theory, +they are by no means proof thereof. For any other theory of Heredity +must suppose the material of heredity to be of a kind more or less +specialized, and the mechanism of heredity extremely precise and well +ordered. And this is all that the facts of karyokinesis prove. Granting +that they prove continuity, they cannot be held to prove that continuity +to be absolute. In other words, the facts are by no means incompatible +with even a large amount of commerce between germ-plasm and +somato-plasm, or a frequent transmission of acquired characters. + +Again, Weismann's theory, that the somatic and the germ-plasm +determinants may be similarly and simultaneously modified by external +conditions may be extended much further than he has used it himself, so +as to exclude, or at any rate invalidate, _all_ evidence in favour of +Lamarckianism, other than the inheritance of the effects of use and +disuse. All evidence from apparently inherited effects produced by +change of external conditions is thus virtually put out of court, +leaving only evidence from the apparently inherited effects of +functionally produced modifications. And this line of evidence is +invalidated by Panmixia. Hence there remain only the arguments from +selective value and co-adaptation. Weismann meets these by adducing the +case of neuter insects, which have been already considered at sufficient +length. + + +(C.) +_Experimental Evidence as to the Non-inheritance of Acquired +Characters._ + + +Let us now proceed to the experimental evidence which has been adduced +on the side of Weismannism. + +Taking this evidence in order of date, we have first to mention that on +which the school of Weismann has hitherto been satisfied almost +exclusively to rely. This is the line of negative evidence, or the +seeming absence of any experimental demonstration of the inheritance of +acquired characters. This kind of evidence, however, presents much less +cogency than is usually supposed. And it has been shown in the last +chapter that the amount of experimental evidence in favour of the +transmission of acquired characters is more considerable than the school +of Weismann seems to be aware--especially in the vegetable kingdom. I do +not think that this negative line of evidence presents much weight; and, +to show that I am not biassed in forming this judgement, I may here +state that few have more reason than myself for appreciating the weight +of such evidence. For, as already stated, when first led to doubt the +Lamarckian factors, now more than twenty years ago, I undertook a +research upon the whole question--only a part of which was devoted to +testing the particular case of Brown-Séquard's statements, with the +result recorded in the preceding chapter. As this research yielded +negative results in all its divisions--and, not only in the matter of +Brown-Séquard's statements--I have not hitherto published a word upon +the subject. But it now seems worth while to do so, and for the +following reasons. + +First, as just observed, a brief account of my old experiences in this +field will serve to show what good reason I have for feeling the weight +of such negative evidence in favour of Continuity as arises from failure +to produce any good experimental evidence to the contrary. In the second +place, now that the question has become one of world-wide interest, it +would seem that even negative results deserve to be published for +whatever they may be worth on the side of Neo-Darwinism. Lastly, in the +third place, although the research yielded negative results in my hands, +it is perhaps not undesirable to state the nature of it, if only to +furnish suggestions to other physiologists, in whose hands the +experiments--especially in these days of antiseptics--may lead to a +different termination. Altogether I made thousands of experiments in +graft-hydridization (comprising bines, bulbs of various kinds, buds, and +tubers); but with uniformly negative results. With animals I tried a +number of experiments in grafting characteristic congenital tissues from +one variety on another--such as the combs of Spanish cocks upon the +heads of Hamburgs; also, in mice and rats, the grafting together of +different varieties; and, in rabbits and bitches, the transplantation of +ovaries of newly-born individuals belonging to different well-marked +breeds. This latter experiment seems to be one which, if successfully +performed (so that the transplanted ovaries would form their attachment +in a young bitch puppy and subsequently yield progeny to a dog of the +same breed as herself) would furnish a crucial test as to the +inheritance or non-inheritance of acquired characters. Therefore I +devoted to it a large share of my attention, and tried the experiment in +several different ways. But I was never able to get the foreign +ovary--or even any portion thereof--to graft. Eventually the passing of +the Vivisection Act caused me to abandon the whole research as far as +animals were concerned--a research, indeed, of which I had become +heartily tired, since in no one instance did I obtain any adhesion. +During the last few years, however, I have returned to these experiments +under a licence, and with antiseptic precautions, but with a similar +want of success. Perhaps this prolonged and uniformly fruitless +experience may now have the effect of saving the time of other +physiologists, by warning them off the roads where there seems to be no +thoroughfare. On the other hand, it may possibly lead some one else to +try some variation in the method, or in the material, which has not +occurred to me. In particular, I am not without hope that the +transplantation of ovaries in very young animals may eventually prove to +be physiologically possible; and, if so, that the whole issue as between +the rival theories of heredity will be settled by the result of a single +experiment. Possibly some of the invertebrata will be found to furnish +the suitable material, although I have been unable to think of any of +these which present sufficiently well-marked varieties for the purpose. +But, pending the successful accomplishment of this particular experiment +in the grafting of any animal tissue, I think it would be clearly +unjustifiable to conclude against the Lamarckian factors on the ground +of any other experiments yielding negative results in but one generation +or even in a large number of sequent generations. + +For instance, the latter consideration applies to the negative results +of Mr. Francis Galton's celebrated _Experiments in Pangenesis_.[82]. +These consisted in transfusing the blood of one variety of rabbit into +the veins of both sexes of another, and then allowing the latter to +breed together: in no case was there any appearance in the progeny of +characters distinctive of the variety from which the transfused blood +was derived. But, as Mr. Galton himself subsequently allowed, this +negative result constitutes no disproof of pangenesis, seeing that only +a portion of the parents' blood was replaced; that this portion, even if +charged with "gemmules," would contain but a very small number of these +hypothetical bodies, compared with those contained in all the tissues of +the parents; and that even this small proportional number would +presumably be soon overwhelmed by those contained in blood newly-made by +the parents. Nevertheless the experiment was unquestionably worth +trying, on the chance of its yielding a positive result; for, in this +event, the question at issue would have been closed. Accordingly I +repeated these experiments (with the kind help of Professor Schäfer), +but with slight differences in the method, designed to give pangenesis a +better chance, so to speak. + + [82] _Proc. R. S. 1871._ + +Thus I chose wild rabbits to supply the blood, and Himalayan to receive +it--the former being the ancestral type (and therefore giving reversion +an opportunity of coming into play), while the latter, although a +product of domestication, is a remarkably constant variety, and one +which differs very much in size and colour from the parent species. +Again, instead of a single transfusion, there were several transfusions +performed at different times. Moreover, we did not merely allow the +blood of one rabbit to flow into the veins of the other (whereby little +more than half the blood could be substituted); but sacrificed three +wild rabbits for refilling the vascular system of each tame one on each +occasion. Even as thus improved, however, the experiment yielded only +negative results, which, therefore, we never published. + +Subsequently I found that all this labour, both on Mr. Galton's part and +our own, was simply thrown away--not because it yielded only negative +results, but because it did not serve as a crucial experiment at all. +The material chosen was unserviceable for the purpose, inasmuch as +rabbits, even when crossed in the ordinary way, never throw intermediate +characters. Needless to say, had I been aware of this fact before, I +should never have repeated Mr. Galton's experiments--nor, indeed, would +he have originally performed them had he been aware of it. So all this +work goes for nothing. The research must begin all over again with some +other animals, the varieties of which when crossed do throw intermediate +characters. + +Therefore I have this year made arrangements for again repeating the +experiments in question--only, instead of rabbits, using well-marked +varieties of dogs. A renewed attack of illness, however, has +necessitated the surrender of this research to other hands, with a +consequent delay in its commencement. + +My ignorance of the unfortunate peculiarity displayed by rabbits in not +throwing intermediate characters has led to a further waste of time in +another line of experiment. On finding that mammalian ovaries did not +admit of being grafted, it seemed to me that the next best thing to try +would be the transplantation of fertilized ova from one variety to +another, for the purpose of ascertaining whether, if a parturition +should take place under such circumstances, gestation by the uterine +mother would affect the characters of the ovum derived from the ovarian +mother--she, of course, having been fertilized by a male of her own +variety. Of course it was necessary that both the mothers should be in +season at about the same time, and therefore I again chose rabbits, +seeing that in the breeding season they are virtually in a chronic state +of "heat." I selected Himalayans and Belgian hares, because they are +well-marked varieties, breed true, and in respect of colour are very +different from one another. It so happened that while I was at work upon +this experiment, it was also being tried, unknown to me, by Messrs. +Heape and Buckley who, curiously enough, employed exactly the same +material. They were the first to obtain a successful result. Two +fertilized ova of the Angora breed having been introduced into the +fallopian tube of a Belgian hare, developed there in due course, and +gave rise to two Angora rabbits in no way modified by their Belgian hare +gestation[83]. + + [83] _Proc. R. S. 1890_, vol. xlviii. p. 457. It should be stated + that the authors do not here concern themselves with any theory + of heredity. + +But, interesting and suggestive as this experiment is in other +connexions, it is clearly without significance in the present one, for +the reason already stated. It will have to be tried on well-marked +varieties of other species of animals, which are known to throw +intermediate characters. Even, however, if it should then yield a +similarly negative result, the fact would not tell against the +inheritance of acquired characters; seeing that an ovum by the time it +is ripe is a finished product, and therefore not to be expected, on any +theory of heredity, to be influenced as to its hereditary potentialities +by the mere process of gestation. On the other hand, if it should prove +that it does admit of being thus affected, so that against all +reasonable expectation the young animal presents any of the hereditary +characters of its uterine mother, the fact would terminate the question +of the transmission of acquired characters--and this quite as +effectually as would a similarly positive result in the case of progeny +from an ingrafted ovary of a different variety. In point of fact, the +only difference between the two cases would be, that in the former it +_might_ prove possible to close the question on the side of +Lamarckianism, in the latter it would _certainly_ close the question, +either on this side or on the opposite as the event would determine. + +The only additional fact that has hitherto been published by the school +of Weismann is the result of Weismann's own experiment in cutting off +the tails of mice through successive generations. But this experiment +does not bear upon any question that is in debate; for no one who is +acquainted with the literature of the subject would have expected any +positive result to follow from such a line of inquiry. As shown further +back in the text, Darwin had carefully considered the case of +mutilations, and explained that their non-transmissibility constitutes +no valid objection to his theory of pangenesis. Furthermore, it may now +be added, he expressly alluded in this connexion to the cutting off of +tails, as practised by horse-breeders and dog-fanciers, "through a +number of generations, without any inherited effect." He also alluded to +the still better evidence which is furnished by the practice of +circumcision. Therefore it is difficult to understand the object of +Weismann's experiment. Yet, other than the result of this experiment, no +new fact bearing on the question at issue has been even so much as +alleged. + + + + +CHAPTER VI. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_conclusion_[84]). + + [84] _See_ note appended to Preface. C. Ll. M. + +In the foregoing chapters I have endeavoured to be, before all things, +impartial; and if it seems that I have been arguing chiefly in favour of +the Lamarckian principles, this has been because the only way of +examining the question is to consider what has to be said on the +affirmative side, and then to see what the negative side can say in +reply. Before we are entitled to discard the Lamarckian factors _in +toto_, we must be able to destroy all evidence of their action. This, +indeed, is what the ultra-Darwinians profess to have done. But is not +their profession premature? Is it not evident that they have not +sufficiently considered certain general facts of nature, or certain +particular results of experiment, which at all events appear +inexplicable by the theory of natural selection alone? In any case the +present discussion has been devoted mainly to indicating such general +facts and particular results. If I have fallen into errors, either of +statement or of reasoning, it is for the ultra-Darwinians to correct +them; but it may be well to remark beforehand, that any criticism of a +merely general kind touching the comparative paucity of the facts thus +adduced in favour of Lamarckian doctrine, will not stand as a valid +criticism. For, as we have seen in the opening part of the discussion, +even if use-inheritance and direct action of the environment have been +of high importance as factors of organic evolution, it must be in almost +all cases impossible to dissociate their influence from that of natural +selection--at any rate where plants and animals in a state of nature are +concerned. On the other hand, experiments expressly devised to test the +question have not hitherto been carried out. Besides, the facts and +arguments here adduced are but _comparatively_ few. For, unless it can +be shown that what has been said of reflex action, instinct, so-called +"self-adaptation" in plants, &c., is wrong in principle, the facts which +tell in favour of Lamarckian theory are _absolutely_ very numerous. Only +when considered in relation to cases where we are unable to exclude the +conceivable possibility of natural selection having been at work, can it +be said that the facts in question are not numerous. + +Comparatively few, then, though the facts may be of which I have given +some examples, in my opinion they are amply sufficient for the purpose +in hand. This purpose is to show that the question which we are now +considering is very far from being a closed question; and, therefore, +that the school of Weismann is much too precipitate in alleging that +there is neither any necessity for, nor evidence of, the so-called +Lamarckian factors[85]. And this opinion, whatever it may be worth, is +at all events both deliberate and impartial. As one of the first to +doubt the transmission of acquired characters, and as one who has spent +many years in experimental inquiries upon the subject, any bias that I +may have is assuredly against the Lamarckian principles--seeing that +nearly all my experiments have yielded negative results. It was Darwin +himself who checked this bias. But if the ultra-Darwinians of the last +ten years had succeeded in showing that Darwin was mistaken, I should be +extremely glad to fall into line with them. As already shown, however, +they have in no way affected this question as it was left by Galton in +1875. And if it be supposed a matter of but little importance whether we +agree with Galton in largely diminishing the comparative potency of the +Lamarckian principles, or whether we agree with Weismann in abolishing +them together, it cannot be too often repeated that such is an entirely +erroneous view. No matter how faintly or how fitfully acquired +characters may be transmitted, in so far as they are likewise adaptive +characters, their transmission (and therefore their development) must be +cumulative. Hence, the only effect of attenuating our estimate of their +_intensity_, is that of increasing our estimate of their +_duration_--i.e. of the time over which they have to operate in order to +produce important results. And, even so, it is to be remembered that +the importance of such results is not to be estimated by the magnitude +of modification. Far more is it to be estimated by the character of +modification as adaptive. For if functionally produced changes, and +changes produced in adaptive response to the environment, are ever +transmitted in a cumulative manner, a time must sooner or later arrive +when they will reach a selective value in the struggle for +existence--when, of course, they will be rapidly augmented by natural +selection. Thus, if in any degree operative at all, the great function +of these principles must be that of supplying to natural selection those +incipient stages of adaptive modifications in all cases where, but for +their agency, there would have been nothing of the kind to select. +Themselves in no way dependent on adaptive modifications having already +attained a selective value, these Lamarckian principles are (under the +Darwinian theory) direct causes of determinate variation in adaptive +lines; and variation in those lines being cumulative, the result is that +natural selection is in large part presented with the raw material of +its manufacture--special material of the particular kinds required, as +distinguished from promiscuous material of all kinds. And the more +complex the manufacture the more important will be the work of this +subordinate factory. We can well imagine how the shell of a nut, for +instance, or even the protective colouring of an insect, may have been +gradually built up by natural selection alone. But just in proportion as +structures or organs are not merely thus of passive _use_ (where, of +course, the Lamarckian principles cannot obtain), but require to be +actively _used_, in that proportion does it become difficult to +understand the _incipient_ construction of them by natural selection +alone. Therefore, in many such cases, if the incipient construction is +not to be explained by the Lamarckian principles, it is difficult to see +how it is to be explained at all. + + [85] E.g. "The supposed transmission of this artificially produced + disease (epilepsy) is the only definite instance which has been + brought forward in support of the transmission of acquired + characters."--_Essays_, p. 328. + +Furthermore, since the question as to the transmission of acquired +characters stands now exactly as it did after the publication of Mr. +Galton's _Theory of Heredity_ twenty years ago, it would seem that our +judgement with regard to it should remain exactly what it was then. +Although we must "out-Darwin Darwin" to the extent of holding that he +assigned too large a measure of intensity to the Lamarckian factors, no +sufficient reason has been shown for denying the existence of these +factors _in toto_; while, on the other hand, there are certain general +considerations, and certain particular facts, which appear to render it +probable that they have played a highly important part in the process of +organic evolution as a whole. At the same time, and in the present state +of our information, this judgement must be deemed provisional, or liable +eventually to be overturned by experimental proof of the non-inheritance +of acquired characters. But, even if this should ever be finally +accomplished, the question would still remain whether the principle of +natural selection alone is capable of explaining all the facts of +adaptation; and, for my own part, I should then be disposed to believe +that there must be some other, though hitherto undiscovered, principle +at work, which co-operates with natural selection, by playing the +subordinate role which was assigned by Darwin to the principles of +Lamarck. + +Finally, let it be noted that no part of the foregoing argument is to be +regarded as directed against the _principle_ of what Professor Weismann +calls "continuity." On the contrary, it appears to be self-evident that +this principle must be accepted in some degree or another by every one, +whether Darwinians, Neo-Darwinians, Lamarckians, Neo-Lamarckians, or +even the advocates of special creation. Yet, to hear or to read some of +the followers of Weismann, one can only conclude that, prior to his +publications on the subject, they had never thought about it at all. +These naturalists appear to suppose that until then the belief of +Darwinians was, that there could be no hereditary "continuity" between +any one organic type and another (such, for instance, as between Ape and +Man), but that the whole structure of any given generation must be due +to "gemmules" or "somato-plasm," derived exclusively from the preceding +generation. Nothing can show more ignorance, or more thoughtlessness, +with regard to the whole subject. The very basis of the general theory +of evolution is that there must always have been a continuity in the +material substance of heredity since the time when the process of +evolution began; and it was not reserved for our generation, or even for +our century, to perceive the special nature of this material substance +in the case of sexual organisms. No, the real and the sole question, +where Weismann's theory of heredity is concerned, is simply this--Are we +to hold that this material substance has been _absolutely_ continuous +"since the first origin of sexual propagation," always occupying a +separate "sphere" of its own, at all events to the extent of never +having been modified by the body substance in which it resides +(Lamarckian factors); _or_, are we to hold that this "germ-plasm," +"stirp," or "formative-material," has been but _relatively_ continuous, +so as to admit of some amount of commerce with body-substance, and +therefore to admit of acquired characters, when sufficiently long +continued as such, eventually becoming congenital? If this question be +answered in the latter sense, of course the further question arises as +to the _degree_ of such commerce, or the _time_ during which acquired +characters must continue to be acquired in successive generations before +they can sufficiently impress themselves on the substance of heredity to +become congenital. But this is a subordinate question, and one which, in +the present state of our information, it seems to me almost useless to +speculate upon. My own opinion has always been the same as that of Mr. +Galton; and my belief is that eventually both Weismann and his followers +will gravitate into it. It was in order to precipitate this result as +far as possible that I wrote the _Examination_. If it ever should be +accomplished, Professor Weismann's elaborate theory of evolution will +have had its bases removed. + + + + +SECTION II + +_UTILITY_ + + + + +CHAPTER VII. + +CHARACTERS AS ADAPTIVE AND SPECIFIC. + + +One of the great changes which has been wrought in biological science by +the Darwinian theory of natural selection, consists in its having +furnished an intelligible explanation of the phenomena of _adaptation_. +Indeed, in my opinion, this is the most important function which this +theory has had to perform; and although we still find systematic +zoologists and systematic botanists who hold that the chief merit of +Darwin's work consists in its having furnished an explanation of the +origin of _species_, a very little consideration is enough to show that +such an idea is but a survival, or a vestige, of an archaic system of +thought. So long as species were regarded as due to separate acts of +creation, any theory which could explain their production by a process +of natural evolution became of such commanding importance in this +respect, that we cannot wonder if in those days the principal function +of Darwin's work was held to be what the title of that work--_The Origin +of Species by means of Natural Selection_--itself serves to convey. And, +indeed, in those days this actually was the principal function of +Darwin's work, seeing that in those days the _fact_ of evolution +itself, as distinguished from its _method_, had to be proved; and that +the whole proof had to stand or fall with the evidence which could be +adduced touching the mutability of species. Therefore, without question, +Darwin was right in placing this issue as to the stability or +instability of species in the forefront of his generalizations, and +hence in constituting it the title of his epoch-making book. But +nowadays, when the fact of evolution has been sufficiently established, +one would suppose it self-evident that the theory of natural selection +should be recognized as covering a very much larger field than that of +explaining the origin of _species_--that it should be recognized as +embracing the whole area of organic nature in respect of _adaptations_, +whether these happen to be distinctive of species only, or of genera, +families, orders, classes, and sub-kingdoms. For it follows from the +general fact of evolution that species are merely arbitrary divisions, +which present no deeper significance from a philosophical point of view +than is presented by well-marked varieties, out of which they are in all +cases believed to have arisen, and from which it is often a matter of +mere individual taste whether they shall be separated by receiving the +baptism of a specific name. Yet, although naturalists are now +unanimously agreed that what they classify as species are nothing +more than pronounced--and in some greater or less degree +permanent--varieties, so forcible is the influence of traditional modes +of thought, that many zoologists and botanists still continue to regard +the origin of species as a matter of more importance than the origin of +adaptations. Consequently, they continue to represent the theory of +natural selection as concerned, primarily, with explaining the origin of +species, and denounce as a "heretic" any one who regards the theory as +primarily a theory of the origin and cumulative development of +adaptations--whether structural or instinctive, and whether the +adaptations are severally characteristic of species only or of any of +the higher taxonomic divisions. Indeed, these naturalists appear to deem +it in some way a disparagement of the theory to state that it is, +primarily, a theory of adaptations, and only becomes secondarily a +theory of species in those comparatively insignificant cases where the +adaptations happen to be distinctive of the lowest order of taxonomic +division--a view of the matter which may fitly be compared to that of an +astronomer who should define the nebular hypothesis as a theory of the +origin of Saturn's rings. It is indeed a theory of the origin of +Saturn's rings; but only because it is a theory of the origin of the +entire solar system, of which Saturn's rings form a part. Similarly, the +theory of natural selection is a theory of the entire system of organic +nature in respect of adaptations, whether these happen to be distinctive +of particular species only, or are common to any number of species. + +Now the outcry which has been raised over this definition of the theory +of natural selection is a curious proof of the opposition which may be +furnished by habitual modes of thought to an exceedingly plain matter of +definition. For, I submit, that no one can deny any of the following +propositions; nor can it be denied that from these propositions the +foregoing definition of the theory in question follows by way of +necessity. The propositions are, first, that natural selection is taken +to be the agency which is mainly, if not exclusively, concerned in the +evolution of adaptive characters: secondly, that these characters, when +evolved, are in some cases peculiar to single species only, while in +other cases, and in process of time, they become the common property of +many species: thirdly, that in cases where they are peculiar to single +species only, they constitute at all events one of the reasons (or even, +as the ultra-Darwinians believe, the only reason) why the particular +species presenting them have come to be species at all. Now, these being +the propositions on which we are all agreed, it obviously follows, of +logical necessity, that the theory in question is primarily one which +explains the existence of adaptive characters wherever these occur; and, +therefore, whether they happen to be restricted to single species, or +are common to a whole group of species. Of course in cases where they +are restricted to single species, the theory which explains the origin +of these particular adaptations becomes also a theory which explains the +origin of these particular species; seeing that, as we are all agreed, +it is in virtue of such particular adaptations that such particular +species exist. Yet even in these cases the theory is, primarily, a +theory of the adaptations in virtue of which the particular species +exists; for, _ex hypothesi_, it is the adaptations which condition the +species, not the species the adaptations. But, as just observed, +adaptations may be the common property of whole groups of species; and +thus the theory of natural selection becomes a theory of the origin of +genera, of families, of orders, and of classes, quite as much as it is a +theory of the origin of species. In other words, it is everywhere a +theory of adaptations; and it is only where the adaptations happen to be +restricted to single species that the theory therefore and incidentally +becomes also a theory of the particular species which presents them. +Hence it is by no means the same proposition to affirm that the theory +of natural selection is a theory of the origin of species, and that it +is a theory of the origin of adaptations, as some of my critics have +represented it to be; for these two things are by no means conterminous. +And in as far as the two propositions differ, it is perfectly obvious +that the latter is the true one. + +Possibly, however, it may be said--Assuredly natural selection is a +theory of the origin (i.e. cumulative development) of adaptations; and, +no less assuredly, although species owe their origin to such +adaptations, there is now no common measure between these two things, +seeing that in numberless cases the same adaptations are the common +property of numberless species. But, allowing all this, we must still +remember that in their _first beginnings_ all these adaptations must +have been distinctive of, or peculiar to, some one particular species, +which afterwards gave rise to a whole genus, family, order, or class of +species, all of which inherited the particular adaptations derived from +this common ancestor, while progressively gaining additional adaptive +characters severally distinctive of their subsequently diverging lines +of descent. So that really all adaptive characters must originally have +been specific characters; and therefore there is no real distinction to +draw between natural selection as a theory of species and as a theory of +adaptations. + +Well, if this objection were to be advanced, the answer would be +obvious. Although it is true that every adaptive character which is now +common to a group of species must originally have been distinctive of a +single parent species, it by no means follows that in its first +beginning as a specific character it appeared in the fully developed +form which it now presents as a generic, family, ordinal, or yet higher +character. On the contrary, it is perfectly certain that in the great +majority of instances such cannot possibly have been the case; and the +larger the group of species over which any particular adaptive character +now extends, the more evidently do we perceive that this character must +itself have been the product of a gradual evolution by natural selection +through an innumerable succession of species in branching lines. The +wing of a bird, for example, is an adaptive structure which cannot +possibly have ever appeared suddenly as a merely specific character: it +must have been slowly elaborated through an incalculable number of +successive species, as these branched into genera, families, and orders +of the existing class. So it is with other class distinctions of an +adaptive kind; and so, in progressively lessening degrees, is it with +adaptive characters of an ordinal, a family, or a generic value. That is +to say, in _all_ cases where an adaptive structure is common to any +considerable group of species, we meet with clear evidence that the +structure has been the product of evolution through the ancestry of +those species; and this evidence becomes increasingly cogent the higher +the taxonomic value of the structure. Indeed, it may be laid down as a +general rule, that the greater the _degree_ of adaptation the greater is +its _diffusion_--both as regards the number of species which present it +now, and the number of extinct species through which it has been handed +down, in an ever ramifying extension and in an ever improving form. +Species, therefore, may be likened to leaves: successive and transient +crops are necessary for the gradual building up of adaptations, which, +like the woody and permanent branches, grow continuously in importance +and efficiency through all the tree of life. Now, in my view, it is the +great office of natural selection to see to the growth of these +permanent branches; and although natural selection has likewise had an +enormously large share in the origination of each successive crop of +leaves--nay, let it be granted to the ultra-Darwinians for the sake of +argument, an exclusive prerogative in this respect--still, in my view, +this is really the least important part of its work. Not as an +explanation of those merely permanent varieties which we call species, +but as an explanation of the adaptive machinery of organic nature, which +has led to the construction both of the animal and vegetable kingdoms in +all their divisions do I regard the Darwinian theory as one of the +greatest generalizations in the history of science. + + * * * * * + +I have dwelt thus at some length upon a mere matter of definition +because, as we shall now find, although it is but a matter of +definition, it is fraught with consequences of no small importance to +the general theory of descent. Starting from an erroneous definition of +the theory of natural selection as primarily a theory of the origin of +species, both friends and foes of the theory have concluded that the +principle of utility must by hypothesis be of universal occurrence so +far as species are concerned; whereas, if once these naturalists were to +perceive that their definition of the theory is erroneous, they would +likewise perceive that their conclusion cannot follow deductively from +the theory itself. If such a conclusion is to be established at all, it +can only be by other and independent evidence of the inductive kind--to +wit, by actual observation. + +Hence we see the importance of starting with an accurate definition of +the theory before proceeding to examine the doctrine of utility as of +universal application to species--a doctrine which, as just stated, has +been habitually and expressly deduced from the theory. This doctrine +occurs in two forms; or, more correctly, there are with reference to +this subject two distinct doctrines, which partly coincide and partly +exclude one another. First, it is held by some naturalists that all +species must necessarily owe their origin to natural selection. And +secondly, it is held by other naturalists, that not only all species, +but likewise all specific characters must necessarily do the same. Let +us consider these two doctrines separately. + +The first, and less extensive doctrine, rests on the deduction that +every species must owe its differentiation as a species to the evolution +of at least one adaptive character, which is peculiar to that species. +Although, when thus originated, a species may come to present any +number of other peculiar characters of a non-adaptive kind, these merely +indifferent peculiarities are supposed to hang, as it were, on the peg +supplied by the one adaptive peculiarity; it is the latter which +conditions the species, and so furnishes an opportunity for any number +of the former to supervene. But without the evolution of at least one +adaptive character there could have been no distinct species, and +therefore no merely adventitious characters as belonging to that +species. I will call this the Huxleyan doctrine, because Professor +Huxley is its most express and most authoritative supporter. + +The second and more extensive doctrine I will call, for the same reason, +the Wallacean doctrine. This is, as already stated, that it follows +deductively from the theory of natural selection, that not only all +species, but even all the distinctive characters of every species, must +necessarily be due to natural selection; and, therefore, can never be +other than themselves useful, or, at the least, correlated with some +other distinctive characters which are so. + +Here, however, I should like to remark parenthetically, that in choosing +Professor Huxley and Mr. Wallace as severally representative of the +doctrines in question, I earnestly desire to avoid any appearance of +discourtesy towards such high authorities. + +I am persuaded--as I shall hereafter seek to show Darwin was +persuaded--that the doctrine of utility as universal where species are +concerned, is, in both the above forms, unsound. But it is less +detrimental in its Huxleyan than in its Wallacean form, because it does +not carry the erroneous deduction to so extreme a point. Therefore let +us first consider the doctrine in its more restricted form, and then +proceed, at considerably greater length, to deal with it in its more +extended form. + + * * * * * + +The doctrine that all _species_ must necessarily be due to natural +selection, and therefore must severally present at least one adaptive +character, appears to me doubly erroneous. + +In the first place, it is drawn from what I have just shown to be a +false premiss; and, in the second place, the conclusion does not follow +even from this premiss. That the premiss--or definition of the theory as +primarily a theory of the origin of species--is false, I need not wait +again to argue. That the conclusion does not follow even from this +erroneous premiss, a very few words will suffice to prove. For, even if +it were true that natural selection is primarily a theory of the origin +of species, it would not follow that it must therefore be a theory of +the origin of _all_ species. This would only follow if it were first +shown that the theory is not merely _a_ theory of the origin of species, +but _the_ theory of the origin of species--i.e. that there can be no +further theory upon this subject, or any cause other than natural +selection which is capable of transforming any single specific type. + +Needless to say, this cannot be shown by way of deduction from the +theory of natural selection itself--which, nevertheless, is the only way +whereby it is alleged that the doctrine is arrived at[86]. + + [86] For a full treatment of Professor Huxley's views upon this + subject, see Appendix II. + + * * * * * + +From the doctrine of utility as advocated by Professor Huxley, we may +now pass on to consider it in the much more comprehensive form advocated +by Mr. Wallace. Of course it is obvious that if the doctrine is +erroneous in its Huxleyan form, much more must it be so in its +Wallacean; and, therefore, that having shown its erroneousness in its +less extended application, there is little need to consider it further +in its more extended form. Looking, however, to its importance in this +more extended application, I think we ought to examine it independently +as thus presented by Mr. Wallace and his school. Let us therefore +consider, on its own merits, the following statement:--It follows +directly from the theory of natural selection that not only all species, +but likewise all specific characters, must be due to natural selection, +and, therefore, must all be of use to the species which present them, or +else correlated with other characters which are so. + +It seems worth while to observe, _in limine_, that this doctrine is +contradicted by that of Professor Huxley. For supposing natural +selection to be the only principle concerned in the origin of all +species, it by no means follows that it is the sole agency concerned in +the origin of all specific characters. It is enough for the former +proposition if only some of the characters distinctive of any given +species--nay, as he very properly expresses it, if only one such +character--has been due to natural selection; for it is clear that, as +he adds, "any number of indifferent [specific] characters" may thus have +been furnished with an opportunity, so to speak, of being produced by +causes other than natural selection. Hence, as previously remarked, the +Huxleyan doctrine, although coinciding with the Wallacean up to the +point of maintaining utility as the only principle which can be +concerned in the origin of species, designedly excludes the Wallacean +doctrine where this proceeds to extend any similar deduction to the case +of specific characters[87]. + + [87] Professor Huxley's views upon this matter are quoted _in + extenso_ in Appendix II. + +In the next place, and with special reference to the Wallacean doctrine, +it is of importance to observe that, up to a certain point there is +complete agreement between Darwinists of all schools. We all accept +natural selection as a true cause of the origin of species (though we +may not all subscribe to the Huxleyan deduction that it is necessarily a +cause of the origin of _all_ species). Moreover, we agree that specific +characters are often what is called rudimentary or vestigial; and, once +more, that our inability to detect the use of any given structure or +instinct is no proof that such a structure or instinct is actually +useless, seeing that it may very probably possess some function hitherto +undetected, or possibly undetectable. Lastly, we all agree that a +structure which is of use may incidentally entail the existence of some +other structure which is not of use; for, in virtue of the so-called +principle of correlation, the useless structure may be an indirect +consequence of natural selection, since its development may be due to +that of the useful structure, with the growth of which the useless one +is correlated. + +Nevertheless, while fully conceding all these facts and principles to +the Wallacean party, those who think with Professor Huxley--and still +more, of course, those few naturalists who think as I do--are unable +to perceive that they constitute any grounds for holding the doctrine +that all specific _characters_ are, or formerly have been, directly or +indirectly due to natural selection. My own reasons for dissenting from +this Wallacean doctrine are as follows. + + * * * * * + +From what has just been said, it will be apparent that the question in +debate is not merely a question of fact which can be settled by a direct +appeal to observation. If this were the case, systematic naturalists +could soon settle the question by their detailed knowledge of the +structures which are severally distinctive of any given group of +species. But so far is this from being the case, that systematic +naturalists are really no better qualified to adjudicate upon the matter +than are naturalists who have not devoted so much of their time to +purely diagnostic work. The question is one of general principles, and +as such cannot be settled by appeals to special cases. For example, +suppose that the rest of this chapter were devoted to a mere enumeration +of cases where it appears impossible to suggest the utility of certain +specific characters, although such cases could be adduced by the +thousand, how should I be met at the end of it all? Not by any one +attempting to suggest the utility, past or present, of the characters +named; but by being told that they must all present some _hidden_ use, +must be _vestigial_, or else must be due to _correlation_. By appealing +to one or other of these assumptions, our opponents are always able to +escape the necessity of justifying their doctrine in the presence of +otherwise inexplicable facts. No matter how many seemingly "indifferent +characters" we may thus accumulate, Mr. Wallace and his followers will +always throw upon us the impossible burden of proving the negative, that +these apparently useless characters do _not_ present some hidden or +former use, are _not_ due to correlation, and therefore have _not_ been +produced by natural selection. It is in vain to retort that the burden +of proof really lies the other way, or on the side of those who affirm +that there is utility where no man can see it, or that there is +correlation where no one can detect it. Thus, so far as any appeal to +particular facts is concerned, it does not appear that there is any +_modus vivendi_. Our opinions upon the question are really determined by +the views which we severally take on matters of general principle. The +issue, though it has a biological bearing, is a logical issue, not a +biological one: it turns exclusively on those questions of definition +and deduction with which we have just been dealing. + +But although it thus follows that we cannot determine in fact what +proportion of apparently useless characters are or are not really +useful, we may very easily determine in fact what proportion of specific +characters _fail to present any observable evidences of utility_. Yet, +even upon this question of observable fact, it is surprising to note the +divergent statements which have of late years been made by competent +writers; statements in fact so divergent that they can only be explained +by some want of sufficient thought on the part of those naturalists who +are antecedently persuaded that all specific characters must be either +directly or indirectly due to natural selection. Hence they fail to give +to apparently useless specific characters the attention which, apart +from any such antecedent persuasion, they deserve. For example, a few +years ago I incidentally stated in a paper before the Linnaean Society, +that "a large proportional number of specific characters" are of a +trivial and apparently unmeaning kind, to which no function admits of +being assigned, and also stated that Darwin himself had expressly given +utterance to the same opinion. When these statements were made, I did +not anticipate that they would be challenged by anybody, except perhaps, +by Mr. Wallace. And, in order now to show that my innocence at that time +was not due to ignorance of contemporary thought on such matters, a +sentence may here be quoted from a paper which was read at the meeting +of the British Association of the same year, by a highly competent +systematic naturalist, Mr. Henry Seebohm, and soon afterwards +extensively republished. Criticizing adversely my then recently +published paper, he said:-- + + "I fully admit the truth of this statement; and I presume that few + naturalists would be prepared to deny that 'distinctions of + specific value frequently have reference to structures which are + without any utilitarian significance[88].'" + + [88] _Geographical Distribution of the Family Charadriidae_, p. 19. + +But since that time the course of Darwinian speculation has been greatly +influenced by the writings of Weismann, who, among other respects in +which he out-darwins Darwin, maintains the doctrine of utility as +universal. In consequence of the influence which these writings have +exercised, I have been more recently and extensively accused of "heresy" +to Darwinian principles, for having stated that "a large proportional +number of specific characters" do not admit of being proved useful, or +correlated with other characters that are useful. Now, observe, we have +here a simple question of fact. We are not at present concerned with the +question how far the argument from ignorance may be held to apply in +mitigation of such cases; but we are concerned only with the question of +fact, as to what proportional number of cases actually occur where we +are _unable to suggest_ the use of specific characters, or the useful +characters with which these apparently useless ones are correlated. I +maintain, as a matter of fact, that the cases in question embrace "a +large proportional number of specific characters." On the other hand, I +am accused of betraying ignorance of species, and of the work of +"species-makers," in advancing this statement; and have been told by Mr. +Wallace, and others of his school, that there is absolutely no evidence +to be derived from nature in support of my views. Well, in the first +place, if this be the case, it is somewhat remarkable that a large body +of competent naturalists, such as Bronn, Broca, Nägeli, Kerner, Sachs, +De Vries, Focke, Henslow, Haeckel, Kölliker, Eimer, Giard, Pascoe, +Mivart, Seebohm, Lloyd Morgan, Dixon, Beddard, Geddes Gulick, and also, +as we shall presently see, Darwin himself, should have fallen into the +same error. And it is further remarkable that the more a man devotes +himself to systematic work in any particular department--whether as an +ornithologist, a conchologist, an entomologist, and so forth--the less +is he disposed to accept the dogma of specific characters as universally +adaptive characters. But, in the second place, and quitting +considerations of mere authority, I appeal to the facts of nature +themselves; and will now proceed, as briefly as possible, to indicate +the result of such an appeal. + +For the following reasons, that birds and mammals seem to furnish the +best field for testing the question by direct observation. First, these +classes present many genera which have been more carefully worked out +than is usually the case with genera of invertebrates, or even of +cold-blooded vertebrates. Secondly, they comprise many genera each +including a large number of species, whose habits and conditions of life +are better known than is the case with species belonging to large genera +of other classes. Thirdly, as birds and mammals represent the highest +products of evolution in respect of organization, a more severe test is +imposed than could be imposed elsewhere, when the question is as to the +utility of specific characters; for if these highest products of +organization fail to reveal, in a large proportional number of cases, +the utility of their specific characters, much more is this likely to be +the case among organic beings which stand lower in the scale of +organization, and therefore, _ex hypothesi_, are less elaborate products +of natural selection. Fourthly, and lastly, birds and mammals are the +classes which Mr. Wallace has expressly chosen to constitute his ground +of argument with regard to the issue on which we are now engaged. + +It would take far too long to show, even in epitome, the results of this +inquiry. Therefore I will only state the general upshot. Choosing genera +of birds and mammals which contain a large number of species whose +diagnostic characters have been worked out with most completeness, I +restricted the inquiry to specific distinctions of colour, not only for +the sake of having a uniform basis for comparisons, but still more +because it seemed that the argument from our ignorance of possibly +unknown uses could be more successfully met in the case of slight +differences of colour or of shading, than in that of any differences of +structure or of form. Finally, after tabulating all the differences of +colour which are given as diagnostic of each species in a genus, and +placing in one column those which may conceivably be useful, while +placing in another column those of which it appeared inconceivable that +any use could be suggested, I added up the figures in the two columns, +and thus obtained a grand total of all the specific characters of the +genus in respect of colours, separated into the two classes of +conceivably useful and apparently useless. Now, in all cases the +apparently useless characters largely preponderated over the conceivably +useful ones; and therefore I abundantly satisfied myself regarding the +accuracy of my previous statement, that a large proportional number--if +not an actual majority--of specific characters belong to the latter +category. + +The following is a brief abstract of these results. + +With respect to Birds, a large number of cases were collected wherein +the characters of allied species differ from one another in such minute +respects of colour or shading, that it seemed unreasonable to suppose +them due to any selective value to the birds in question. It is +needless--even if it were practicable on the present occasion--to +adduce this evidence in detail, since an exceedingly good sample of it +may be found in a small book which is specially devoted to considering +the question in its relation to birds. I allude to an essay by Mr. +Charles Dixon, entitled _Evolution without Natural Selection_ (1885). In +this work Mr. Dixon embodies the results of five years' "careful working +at the geographical distribution and variations of plumage of +Palaearctic birds and their allies in various other parts of the world"; +and shows, by a large accumulation of facts, not only that there is no +utility to be suggested in reference to the minute or trivial +differences of colouration which he describes; but also that these +differences are usually correlated with isolation on the one hand, or +with slight differences of climate on the other. Now it will be shown +later on that both these agents can be proved, by independent evidence, +capable of inducing changes of specific type without reference to +utility: therefore the correlation which Mr. Dixon unquestionably +establishes between apparently useless (because utterly trivial) +specific distinctions on the one hand, and isolation or climatic change +on the other, constitutes additional evidence to show that the +uselessness is not only apparent, but real. Moreover I have collected a +number of cases where such minute differences of colour between allied +species of birds happen to affect parts of the plumage which are +_concealed_--as for instance, the breast and abdomen of creepers. In +such cases it seems impossible to suggest how natural selection can have +operated, seeing that the parts affected are not exposed to the view +either of enemies or of prey. + +Analogous illustrations to any amount may be drawn from Mammals. For +instance, I have worked through the Marsupials with the aid of Mr. +Oldfield Thomas' diagnostic description of their numerous species. Now, +let us take any one of the genera, such as the kangaroos. This comprises +23 species living on an island continent of high antiquity, and not +exposed to the depredations of any existing carnivorous enemies; so that +there is here no present need to vary colour for purposes of protection. +Moreover, in all cases the diagnostic distinctions of colour are so +exceedingly trivial, that even if large carnivora were recently abundant +in Australia, no one could reasonably suggest that the differences in +question would then have been protective. On an average, each of the 23 +species presents rather more than 20 peculiarities of shading, which are +quoted as specifically diagnostic. Altogether there are 474 of these +peculiarities distributed pretty evenly among the 23 species; and in no +case can I conceive that utility can be suggested. + + * * * * * + +Hitherto we have been considering the question of fact, as to whether "a +large proportional number of specific characters" do or do not admit of +having their utility demonstrated, or even so much as plausibly +suggested. In the result, I can only conclude that this question of fact +is really not an open one, seeing that it admits of an abundantly +conclusive answer by any naturalist who will take the trouble to work +through the species of any considerable number of genera in the way +above indicated. But although the question of fact is thus really +closed, there remains a more ultimate question as to its theoretical +interpretation. For, as already pointed out, no matter how great an +accumulation of such facts may be collected, our opponents are always +able to brush them aside by their _a priori_ appeal to the argument from +ignorance. In effect they say--We do not care for any number of +thousands of such facts; it makes no difference to us what "proportional +number" of specific characters fail to show evidence of utility; you are +merely beating the air by adducing them, for we are already persuaded, +on antecedent grounds, that _all_ specific characters _must_ be either +themselves useful, or correlated with others that are, whether or not we +can perceive the utility, or suggest the correlation. + +To this question of theoretical interpretation, therefore, we must next +address ourselves. And here, first of all, I should like to point out +how sturdy must be the antecedent conviction of our opponents, if they +are to maintain it in the face of such facts as have just been adduced. +It must be remembered that this antecedent conviction is of a most +uncompromising kind. By its own premisses it is committed to the +doctrine that _all_ specific characters, without a single exception, +_must_ be either useful, vestigial, or correlated. Well, if such be the +case, is it not somewhat astonishing that out of 474 differences of +colour which are distinctive of the 23 species of the genus Macropus, no +single one appears capable of having any utility demonstrated, or indeed +so much as suggested? For even the recent theory that slight differences +of colour, which cannot be conceived as serving any other purpose, may +enable the sexes of the same species quickly to recognize each other, is +not here available. The species of the genus Macropus are more +conspicuously distinguished by differences of size and form than by +these minute differences of colour; and therefore no such use can be +attributed to the latter. And, as previously stated, even within the +order Marsupialia the genus Macropus is not at all exceptional in this +respect; so that by including other genera of the order it would be easy +to gather such apparently indifferent specific characters by the +hundred, without any one of them presenting evidence--or even +suggestion--of utility. How robust therefore is the faith of an _a +priori_ conviction which can stand against such facts as these! What, +then, are the _a priori_ grounds on which it stands? Mr. Wallace, the +great leader of this school of thought, says:-- + + "It is a necessary deduction from the theory of natural selection, + that none of the definite facts of organic nature, no special + organ, no characteristic form or marking, no peculiarities of + instinct or of habit, no relations between species or between + groups of species, can exist, but which must now be, or once have + been, _useful_ to the individuals or the races which possess + them[89]." + + [89] _Contributions to the Theory of Natural Selection_, p. 47 + (1870); republished in 1892. + +Here, then, we have in brief compass the whole essence of our opponents' +argument. It is confessedly an argument _a priori_, a deduction from the +theory of natural selection, a supposed consequence of that theory which +is alleged to be so necessary that to dispute the consequence is +tantamount to denying the theory from which it is derived. In short, as +before stated, it is a question of theory, not a question of fact: our +difference of opinion is logical, not biological: it depends on our +interpretation of principles, not on our observation of species. It will +therefore be my endeavour to show that the reasoning in question is +fallacious: that it is _not_ a necessary deduction from the theory of +natural selection that no characteristic form or marking, no +peculiarities of instinct or of habit, can exist, but which must now be, +or once have been, useful, or correlated with some other peculiarity +that is useful. + +"The tuft of hair on the breast of a wild turkey-cock _cannot be of any +use_, and it is doubtful whether it can be ornamental in the eyes of the +female bird;--indeed, had the tuft appeared under domestication, it +would have been called a monstrosity[90]." + + [90] _Origin of Species_, p. 70: italics mine. + +As a matter of common sense, unprejudiced by dogma, this appears to be a +perfectly sound judgement; but if Wallace had asked Darwin to prove such +a negative, Darwin could only have replied that it was for Wallace to +prove the affirmative--and thus the issue would have been thrown back +upon a discussion of general principles. Then Wallace would have +said--"The assertion of inutility in the case of any organ or +peculiarity which is not a rudiment or a correlation _is not, and can +never be_, the statement of a fact, but _merely an expression of our +ignorance of its purpose or origin_[91]." Darwin, however, would have +replied:--"Our ignorance of the laws of variation is profound"; and +while, on this account, we ought "to be extremely cautious in +_pretending to decide what structures are now, or have formerly been, of +use to each species_," in point of fact "there can be little doubt that +the tendency to vary in the same manner has _often_ been so strong, that +_all_ individuals of the same _species_ have been similarly modified +_without the aid of any form of selection_[92]." + + [91] _Darwinism_, p. 137: italics mine. + + [92] _Origin of Species_, p. 72: Mr. Wallace himself quotes this + passage (_Darwinism_, p. 141); but says with regard to it "the + important word 'all' is probably an oversight." In the Appendix + (II), on Darwin's views touching the doctrine of utility I + adduce a number of precisely equivalent passages, derived from + all his different works on evolution, and _every one of them_ + presenting "the important word 'all.'" + +It will be my endeavour in the following discussion to show that Darwin +would have had an immeasurable advantage in this imaginary debate. + +To begin with, Wallace's deductive argument is a clear case of circular +reasoning. We set out by inferring that natural selection is a cause +from numberless cases of observed utility as an effect: yet, when "in a +large proportional number" of cases we fail to perceive any imaginable +utility, it is argued that nevertheless utility must be there, since +otherwise natural selection could not have been the cause. + +Be it observed, in any given case we may properly anticipate utility as +_probable_, even where it is not perceived; because there are already so +enormous a number of cases where it is perceived, that, if the principle +of natural selection be accepted at all, we must conclude with Darwin +that it is "the _main_ means of modification." Therefore, in particular +cases of unperceived utility we may take this antecedent probability as +a guide in our biological researches--as has been done with such +brilliant success both by Darwin and Wallace, as well as by many of +their followers. But this is a very different thing from laying down the +universal maxim, that in _all_ cases utility _must_ be present, whether +or not we shall ever be able to detect it[93]. For this universal maxim +amounts to an assumption that natural selection has been the +"_exclusive_ means of modification." That it has been "the main means of +modification" is proved by the generality of the observed facts of +adaptation. That it has been "the exclusive means of modification," with +the result that these facts are universal, cannot be thus proved by +observation. Why, then, is it alleged? Confessedly it is alleged by way +of deduction from the theory of natural selection itself. Or, as above +stated, after having deduced the theory from the facts, it is sought to +deduce the facts from the theory. + + [93] See Introductory Chapter, p. 20. + +Thus far I have been endeavouring to show that the universality of +adaptation cannot be inferred from its generality, or from the theory of +natural selection itself. But, of course, the case would be quite +different if there were any independent evidence--or rather, let us say, +any logical argument--to show that natural selection is "the exclusive +means of modification." For in this event it would no longer involve +circular reasoning to maintain that all specific characters are likewise +adaptive characters. It might indeed appear antecedently improbable that +no other principle than natural selection can possibly have been +concerned in the differentiation of those relatively permanent varieties +which we call species--that in all the realm of organic nature, and in +all the complexities of living processes, there is no room for any +other influence in the production of change, even of the most trivial +and apparently unmeaning kind. But if there were any good evidence or +logical argument to the contrary, this antecedent presumption would have +to give way; and the certainty that all specific characters are likewise +adaptive characters would be determined by the cogency of such evidence +or argument as could be adduced. In short, we are not entitled to +conclude--and still less does it follow "as a necessary deduction from +the theory of natural selection"--that all the details of specific +differentiation must in every case be either useful, vestigial, or +correlated, _unless it has been previously shown, by independent +evidence, or accurate reasoning, that there is no room for any other +principle of specific change_. + +This, apparently, is the central core of the question. Therefore I will +now proceed to consider such arguments as have been adduced to prove +that, other than natural selection, there _can_ have been no "means of +modification." And, after having exhibited the worthlessness of these +arguments, I will devote the next chapter to showing that, as a matter +of observable fact, there _are_ a considerable number of other +principles, which can be proved to be capable of producing such minute +differences of form and colour as "in a large proportional number" of +cases constitute diagnostic distinctions between species and species. + +First, then, for the reasons _a priori_--and they are confessedly _a +priori_--which have been adduced to prove that natural selection has +been what in Darwin's opinion it has not been,--"the _exclusive_ means +of modification." Disregarding the Lamarckian factors--which, even if +valid, have but little relation to the present question, seeing that +they are concerned, almost exclusively, with the evolution of _adaptive_ +characters--it is alleged that natural selection must occupy the whole +field, because no other principle of change can be allowed to operate in +the presence of natural selection. Now, I fully agree that this +statement may hold as regards any principle of change which is +deleterious; but clearly it does not hold as regards any principle which +is merely neutral. If any one were to allege that specific characters +are frequently detrimental to the species presenting them, he would no +doubt lay himself open to the retort that natural selection could not +allow such characters to persist; or, which amounts to the same thing, +that it _does_ "necessarily follow from the theory of natural selection" +that specific characters can never be in any large number, or in any +large measure, _harmful_ to the species presenting them. But where +the statement is that specific characters are frequently +_indifferent_--again to use Professor Huxley's term--the retort loses +all its relevancy. No reason has ever been shown why natural selection +should interfere with merely indifferent characters, supposing such to +have been produced by any of the agencies which we shall presently have +to consider. Therefore this argument--or rather assertion--goes for +nothing. + +The only other argument I have met with on this side of the question is +one that has recently been adduced by Mr. Wallace. He says:-- + + "One very weighty objection to the theory that _specific_ + characters can ever be wholly useless appears to have been + overlooked by those who have maintained the frequency of such + characters, and that is, their almost necessary instability[94]." + + [94] _Darwinism_, p. 138. + +This argument he proceeds to elaborate at considerable length, but fails +to perceive what appears to me the obvious answer. Provided that the +cause of the useless character is constant, there is no difficulty in +understanding why the character is stable. Utility is not the only +principle that can lead to stability: any other principle must do the +same, provided that it acts for a sufficient length of time, and with a +sufficient degree of uniformity, on all the individuals of a species. +This is a consideration the cogency of which was clearly recognized by +Darwin, as the following quotations will show. Speaking of unadaptive +characters, he says they may arise as merely + + "fluctuating variations, which sooner or later become _constant_ + through the nature of the organism and of surrounding conditions, + _but not through natural selection_[95]." + + [95] _Origin of Species_, p. 176: italics mine, as also in the + following. + +Elsewhere we read:-- + + "Each of the endless variations which we see in the plumage of our + fowls must have had some efficient cause; and if the _same_ cause + were to act _uniformly_ during a long series of generations on + _many_ individuals, _all_ probably would be modified in the same + manner." + +As special illustrations of this fact I may quote the following cases +from Darwin's works. + + "Dr. Bachman states that he has seen turkeys raised from the eggs + of wild species, lose their metallic tints, and become spotted in + the third generation. Mr. Yarrell many years ago informed me that + the wild ducks bred in St James' Park lost their true plumage + after a few generations. An excellent observer (Mr. Hewitt) ... + found that he could not breed wild ducks true for more than five or + six generations, as they proved so much less beautiful. The white + collar round the neck of the mallard became broader and more + irregular, and white feathers appeared in the duckling's wings + &c.[96]" + + [96] _Var._ vol. ii. p. 250. + +Now, such cases--to which numberless others might be added--prove that +even the subtle and inconspicuous causes incidental to domestication are +capable of inducing changes of specific character quite as great, and +quite as "stable," as any that in a state of nature are taken to +constitute specific distinctions. Yet there can here be no suggestion of +utility, inasmuch as the change takes place in the course of a few +generations, and therefore without leaving time for natural selection to +come into play--even if it ever could come into play among the sundry +domesticated birds in question. + +But the facts of domestication also make for the same conclusion in +another way--namely, by proving that when time enough _has_ been allowed +for the production of useless changes of greater magnitude, such changes +are not infrequently produced. And the value of this line of evidence is +that, great as are the changes, it is impossible that either natural or +artificial selection can have been concerned in their production. It +will be sufficient to give two examples--both with regard to structure. + +The first I will render in the words whereby it has already been stated +in my own paper on _Physiological Selection_, because I should like to +take this opportunity of answering Mr. Wallace's objection to it. + + "Elsewhere (_Origin of Species_, p. 158) Mr. Darwin points out that + modifications which appear to present obvious utility are often + found on further examination to be really useless. This latter + consideration, therefore, may be said to act as a foil to the one + against which I am arguing, namely, that modifications which appear + to be useless may nevertheless be useful. But here is a still more + suggestive consideration, also derived from Mr. Darwin's writings. + Among our domesticated productions changes of structure--or even + structures wholly new--not unfrequently arise, which are in every + way analogous to the apparently useless distinctions between wild + species. Take, for example, the following most instructive case:-- + + [Illustration: Fig. 2.--Old Irish Pig, showing jaw-appendages + (after Richardson).] + + "'Another curious anomaly is offered by the appendages described by + M. Eudes-Deslongchamps as often characterizing the Normandy pigs. + These appendages are always attached to the same spot, to the + corners of the jaws; they are cylindrical, about three inches in + length, covered with bristles, and with a pencil of bristles rising + out of a sinus on one side; they have a cartilaginous centre with + two small longitudinal muscles; they occur either symmetrically on + both sides of the face, or on one side alone. Richardson figures + them on the gaunt old Irish Greyhound pig; and Nathusius states + that they occasionally appear in all the long-eared races, but are + not strictly inherited, for they occur or fail in the animals of + the same litter. As no wild pigs are known to have analogous + appendages, we have at present no reason to suppose that their + appearance is due to reversion; and if this be so, we are forced to + admit that a somewhat complex, though apparently useless, structure + may be suddenly developed without the aid of selection[97].'" + + [97] _Variation_, &c. vol. i. pp. 78-79. + +To this case Mr. Wallace objects:-- + + "But it is expressly stated that they are not constant; they appear + 'frequently' or 'occasionally,' they are 'not strictly inherited, + for they occur or fail in animals of the same litter'; and they are + not always symmetrical, sometimes appearing on one side of the face + alone. Now, whatever may be the cause or explanation of these + anomalous appendages, they cannot be classed with 'specific + characters,' the most essential features of which are, that they + _are_ symmetrical, that they _are_ inherited, and that they _are_ + constant[98]." + + [98] _Darwinism_, pp. 139-40. + +But, to begin with, I have not classed these appendages with "specific +characters," nor maintained that Normandy pigs ought to be regarded as +specifically distinct on account of them. What I said was:-- + + "Now, if any such structure as this occurred in a wild species, and + if any one were to ask what is the use of it, those who rely on the + argument from ignorance would have a much stronger case than they + usually have; for they might point to the cartilage supplied with + muscles, and supporting a curious arrangement of bristles, as much + too specialized a structure to be wholly meaningless. Yet we happen + to know that this particular structure is wholly meaningless[99]." + + [99] Mr. Wallace deems the concluding words "rather confident." I + was not, however, before aware that he extended his _a priori_ + views on utility to domesticated varieties which are bred for + the slaughter-house. If he now means to indicate that these + appendages are possibly due to natural selection, he is surely + going very far to save his _a priori_ dogma; and in the case + next adduced will have to go further still. + +In the next place, is it either fair or reasonable to expect that a +varietal character of presumably very recent origin should be as +strongly inherited--and therefore as constant both in occurrence and +symmetry--as a true specific character, say, of a thousand times its +age? Even characters of so-called "constant varieties" in a state of +nature are usually less constant than specific characters; while, again, +as Darwin says, "it is notorious that specific characters are more +variable than generic,"--the reason in both cases being, as he proceeds +to show, that the less constant characters are characters of more recent +origin, and therefore less firmly fixed by heredity[100]. Hence I do not +understand how Mr. Wallace can conclude, as he does, "that, admitting +that this peculiar appendage is wholly useless and meaningless, the fact +would be rather an argument against specific characters being also +meaningless, because the latter never have the characteristics [i.e. +inconstancy of occurrence, form, and transmission] which this particular +variation possesses[101]." Mr. Wallace can scarcely suppose that when +specific characters first arise, they present the three-fold kind of +constancy to which he here alludes. But, if not, can it be denied that +these peculiar appendages appear to be passing through a phase of +development which all "specific characters" must have passed through, +before they have had time enough to be firmly fixed by heredity[102]? + + [100] _Origin of Species_, pp. 122-3. + + [101] _Darwinism_, p. 140. + + [102] In the next paragraph Mr. Wallace says that the appendages in + question "are apparently of the same nature as the 'sports' + that arise in our domesticated productions, but which, as Mr. + Darwin says, without the aid of selection would soon + disappear." But I cannot find that Mr. Darwin has made any + such statement: what he does say is, that whether or not a + useless peculiarity will soon disappear without the aid of + selection depends upon the nature of the causes which produce + it. If these causes are of a merely transitory nature, the + peculiarity will also be transitory; but if the causes be + constant, so will be the result. Again, the point to be + noticed about this "sport" is, that, unlike what is usually + understood by a "sport," it affects a whole race or breed, is + transmitted by sexual propagation, and has already attained so + definite a size and structure, that it can only be reasonably + accounted for by supposing the continued operation of _some + constant_ cause. This cause can scarcely be correlation of + growth, since closely similar appendages are often seen in so + different an animal as a goat. Here, also, they run in breeds + or strains, are strongly inherited, and more "constant," as + well as more "symmetrical" than they are in pigs. This, at all + events, is the account I have received of them from + goat-breeders in Switzerland. + +If, however, even this should be denied, what will be said of the second +case, that of the niata cattle? + + "I saw two herds on the northern bank of the Plata.... The forehead + is very short and broad, with the nasal end of the skull, together + with the whole plane of the upper molar-teeth, curved upwards. The + lower jaw projects beyond the upper, and has a corresponding upward + curvature.... The skull which I presented to the College of + Surgeons has been thus described by Professor Owen. 'It is + remarkable from the stunted development of the nasals, + premaxillaries, and fore part of the lower jaw, which is unusually + curved upwards to come into contact with the premaxillaries. The + nasal bones are about one-third the ordinary length, but retain + almost their normal breadth. The triangular vacuity is left between + them and the frontal and lachrymal, which latter bone articulates + with the premaxillary, and thus excludes the maxillary from any + junction with the nasal.' So that even the connexion of some of + the bones is changed. Other differences might be added: thus the + plane of the condyles is somewhat modified, and the terminal edge + of the premaxillaries forms an arch. In fact, on comparison with + the skull of a common ox, scarcely a single bone presents the same + exact shape, and the whole skull has a wonderfully different + appearance[103]." + + [103] Darwin, _Variation_, &c., vol. i. pp. 92-4. + +[Illustration: Fig. 3.--Drawn from nature. R. Coll. Surg. Mus.] + +As I cannot find that this remarkable skull has been figured before, I +have had the accompanying woodcut made in order to compare it with the +skull of a Charsley Forest ox; and a glance is sufficient to show what +"a wonderfully different appearance" it presents. + + * * * * * + +Now the important points in the present connexion with regard to this +peculiar race of cattle are the following. + +Their origin is not known; but it must have been subsequent to the year +1552, when cattle were first introduced to America from Europe, and it +is known that such cattle have been in existence for at least a century. +The breed is very true, and a niata bull and cow invariably produce +niata calves. A niata bull crossed with a common cow, and the reverse +cross, yield offspring having an intermediate character, but with the +niata peculiarities highly conspicuous[104]. + + [104] _Ibid._ p. 94. + +Here, then, we have unquestionable evidence of a whole congeries of very +distinctive characters, so unlike anything that occurs in any other +cattle, that, had they been found in a state of nature, they would have +been regarded as a distinct species. And the highly peculiar characters +which they present conform to all "the most essential features of +specific characters," as these are stated by Mr. Wallace in his +objection to the case of the pig's appendages. That is to say, "they +_are_ symmetrical, they _are_ inherited, and they _are_ constant." In +point of fact, they are _always_ "constant," both as to occurrence and +symmetry, while they are so completely "inherited" that not only does "a +niata bull and cow _invariably_ produce niata calves"; but even when +crossed with other cattle the result is a _hybrid_, "with the niata +character _strongly_ displayed." + +Hence, if we were to follow Mr. Wallace's criteria of specific +characters, which show that the pig's appendages "cannot be classed with +specific characters" (or with anything of the nature of specific +characters), it would follow that the niata peculiarities _can_ be so +classed. This, therefore, is a case where he will find all the reasons +which in other cases he takes to justify him in falling back upon the +argument from ignorance. The cattle are half wild, he may urge; and so +the three-fold constancy of their peculiar characters may very well be +due, either directly or indirectly, to natural selection--i.e. they may +either be of some hidden use themselves, or correlated with some other +modifications that are of use: it is, he may say, as in such cases he +often does say, for us to disprove both these possibilities. + +Well, here we have one of those rare cases where historical information, +or other accidents, admit of our discharging this burden of proving a +negative. Darwin's further description shows that this customary refuge +in the argument from ignorance is most effectually closed. For-- + + "When the pasture is tolerably long, these cattle feed as well as + common cattle with their tongue and palate; but during the great + droughts, when so many animals perish on the Pampas, the niata + breed lies under a great disadvantage, and would, if not attended + to, become extinct; for the common cattle, like horses, are able to + keep alive by browsing with their lips on the twigs of trees and on + reeds; this the niatas cannot so well do, as their lips do not + join, and hence they are found to perish before the common cattle. + This strikes me as a good illustration of how little we are able to + judge from the ordinary habits of an animal, on what circumstances, + occurring only at long intervals of time, its rarity or extinction + may depend. It shows us, also, how natural selection would have + determined the rejection of the niata modification, had it arisen + in a state of nature[105]." + + [105] Darwin, _Variation_, &c. vol. i. p. 94. + +Hence, it is plainly _impossible_ to attribute this modification to +natural selection, either as acting directly on the modified parts +themselves, or indirectly through correlation of growth. And as the +modification is of specific magnitude on the one hand, while it presents +all "the most essential features of specific characters" on the other, I +do not see any means whereby Mr. Wallace can meet it on his _a priori_ +principles. It would be useless to answer that these characters, +although conforming to all his tests of specific characters, differ in +respect of being deleterious, and would therefore lead to extermination +were the animals in a wholly wild state; because, considered as an +argument, this would involve the assumption that, apart from natural +selection, only deleterious characters can arise under nature--i. e. +that merely "indifferent" characters can never do so, which would be +absurd. Indeed, I have chosen this case of the niata cattle expressly +because their strongly marked peculiarities _are_ deleterious, and +therefore exclude Mr. Wallace's appeal to the argument from ignorance of +a possible utility. But if even these pronounced and deleterious +peculiarities can arise and be perpetuated with such constancy and +fidelity, much more is this likely to be the case with less pronounced +and merely neutral peculiarities. + +It may, however, be further objected that these cattle are not +improbably the result of _artificial_ selection. It may be suggested +that the semi-monstrous breed originated in a single congenital +variation, or "sport," which was isolated and multiplied as a curiosity +by the early settlers. But even if such be the explanation of this +particular case, the fact would not weaken our illustration. On the +contrary, it would strengthen our general argument, by showing an +additional means whereby indifferent specific characters can arise and +become fixed in a state of nature. As it seems to me extremely probable +that the niata cattle did originate in a congenital monstrosity, which +was then isolated and multiplied by human agency (as is known to have +been the case with the "ancon sheep"), I will explain why this tends to +strengthen our general argument. + +It is certain that if these animals were ever subject to artificial +isolation for the purpose of establishing their breed, the process must +have ceased a long time ago, seeing that there is no memory or tradition +of its occurrence. Now this proves that, however the breed may have +originated, it has been able to maintain its many and highly peculiar +characters for a number of generations without the help of selection, +either natural or artificial. This is the first point to be clear upon. +Be its origin what it may, we know that this breed has proved capable of +perpetuating itself with uniform "constancy" for a number of generations +after the artificial selection has ceased--supposing such a process ever +to have occurred. And this certain fact that artificial selection, even +if it was originally needed to establish the type, has not been needed +to perpetuate the type, is a full answer to the supposed objection. For, +in view of this fact, it is immaterial what the origin of the niata +breed may have been. In the present connexion, the importance of this +breed consists in its proving the subsequent "stability" of an almost +monstrous form, continued through a long series of generations by the +force of heredity alone, without the aid of any form of selection. + +The next point is, that not only is a seeming objection to the +illustration thus removed, but that, if we do entertain the question of +origin, and if we do suppose the origin of these cattle to have been in +a congenital "sport," afterwards multiplied by artificial isolation, we +actually strengthen our general argument by increasing the importance of +this particular illustration. For the illustration then becomes +available to show how indifferent specific characters may sometimes +originate in merely individual sports, which, if not immediately +extinguished by free intercrossing, will perpetuate themselves by the +unaided force of heredity. But this is a point to which we shall recur +in the ensuing chapter. + +In conclusion, it is worth while to remark, with regard to Mr. Wallace's +argument from constancy, that, as a matter of fact, utility does not +seem to present any greater power in securing "stability of characters" +than any other cause of like constancy. Thus, for instance, whatever the +causes may have been which have produced and perpetuated the niata breed +of cattle, they have certainly produced a wonderful "stability" of a +great modification in a wonderfully short time. And the same has to be +said of the ducks in St. James' Park, as well as sundry other cases. On +the other hand, when, as in the case of numberless natural species, +modification has been undoubtedly produced by natural selection, +although the modification must have had a very much longer time in which +to have been fixed by heredity, it is often far from being +stable--notwithstanding that Mr. Wallace regards stability as a +criterion of specific characters. Indeed--and this is more suggestive +still--there even seems to be a kind of _inverse_ proportion between the +utility and the stability of a specific character. The explanation +appears to be (_Origin of Species_, pp. 120-2), that the more a specific +character has been forced on by natural selection on account of its +utility, the less time will it have had to become well fixed by heredity +before attaining a full development. Moreover, as Darwin adds, in cases +where the modification has not only been thus "comparatively recent," +but also "extraordinarily great," the probability is that the parts so +modified must have been very variable in the first instance, and so are +all the more difficult to render constant by heredity. Thus we see that +utility is no better--even if it be so good--a cause of stability in +specific characters, as are the unknown causes of stability in many +varietal characters[106]. + + [106] Should it be objected that useless characters, according to my + own view of the Cessation of Selection, ought to disappear, + and therefore cannot be constant, the answer is evident. For, + by hypothesis, it is only those useless characters which were + at one time useful that disappear under this principle. + Selection cannot cease unless it was previously present--i.e. + save in cases where the now useless character was originally + due to selection. Hence, in all cases where it was due to any + other cause, the useless character will persist at least as + long as its originating cause continues to operate. And even + after the latter (whatever it may be) has ceased to operate, + the useless character will but slowly degenerate, until the + eventual failure of heredity causes it to disappear _in + toto_--long before which time it may very well have become a + genetic, or some higher, character. + + + + +CHAPTER VIII. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_continued_). + + +Let us now proceed to indicate some of the causes, other than natural +selection, which may be regarded as adequate to induce such changes in +organic types as are taken by systematists to constitute diagnostic +distinctions between species and species. We will first consider causes +external to organisms, and will then go on to consider those which occur +within the organisms themselves: following, in fact, the classification +which Darwin has himself laid down. For he constantly speaks of such +causes as arising on the one hand, from "changed conditions of life" +and, on the other hand, from "the nature of the organism"--that is, from +internal processes leading to "variations which seem to us in our +ignorance to arise spontaneously." + +In neither case will it be practicable to give more than a brief +_résumé_ of all that might be said on these interesting topics. + + +I. _Climate._ + +There is an overwhelming mass of evidence to prove that the assemblage +of external conditions of life conveniently summarized in the word +Climate, exercise a potent, an uniform, and a permanent influence on +specific characters. + +With regard to plants, Darwin adduces a number of facts to show the +effects of climate on wheat, cabbages, and other vegetables. Here, for +example, is what he says with regard to maize imported from America to +Germany:-- + + "During the first year the plants were twelve feet high, and a few + seeds were perfected; the lower seeds in the ear kept true to their + proper form, but the upper seeds became slightly changed. In the + second generation the plants were from nine to ten feet high, and + ripened their seed better; the depression on the outer side of the + seed had almost disappeared, and the original beautiful white + colour had become duskier. Some of the seeds had even become + yellow, and in their now rounded form they approached the common + European maize. In the third generation nearly all resemblance to + the original and very distinct American parent-form was lost[107]." + + [107] _Variation_, &c. vol. i. p. 340. + +As these "highly remarkable" changes were effected in but three +generations, it is obvious that they cannot have been dependent on +selection of any kind. The same remark applies to trees. Thus,-- + + "Mr. Meehan has compared twenty-nine kinds of American trees with + their nearest European allies, all grown in close proximity and + under as nearly as possible the same conditions. In the American + species he finds, with the rarest exceptions, that the leaves fall + earlier in the season, and assume before their fall a brighter + tint; that they are less deeply toothed or serrated; that the buds + are smaller; that the trees are more diffuse in growth and have + fewer branchlets; and, lastly, that the seeds are smaller--all in + comparison with the corresponding European species. Now, + considering that these corresponding trees belong to several + distinct orders, and that they are adapted to widely different + stations, it can hardly be supposed that their differences are of + any special service to them in the New and Old worlds; and, if so, + such differences cannot have been gained through natural selection, + and must be attributed to the long continued action of a different + climate[108]." + + [108] _Variation_, &c. vol. ii. p. 271. + +These cases, however, I quote mainly in order to show Darwin's opinion +upon the matter, with reference to the absence of natural selection. +For, where the vegetable kingdom is concerned, the fact of climatic +variation is so general, and in its relation to diagnostic work so +important, that it constitutes one of the chief difficulties against +which species-makers have to contend. And the more carefully the subject +is examined the greater does the difficulty become. But, as to this and +other general facts, it will be best to allow a recognized authority to +speak; and therefore I will give a few extracts from Kerner's work on +_Gute und schlechte Arten_. + +He begins by showing that geographical (or it may be topographical) +varieties of species are often so divergent, that without a knowledge of +intermediate forms there could be no question as to their being good +species. As a result of his own researches on the subject, he can +scarcely find language strong enough to express his estimate of the +extent and the generality of this source of error. In different parts of +Europe, or even in different parts of the Alps, he has found these +climatic varieties in such multitudes and in such high degrees both of +constancy and divergence, that, after detailing his results, he +finishes his essay with the following remarkable conclusions:-- + + "Die Wissenchaft geht aber ihren Entwicklungsgang im grossen Ganzen + gerade so, wie die Erkenntniss bei jedem einzelnen Naturforscher. + Fast jeder Botaniker muss seinen Entwicklungsgang durchmachen und + gelangt endlich mehr oder weniger nahe zu demselben Ziele. Die + Ungleichheit besteht nur darin, dass der eine langsamer, der andere + aber rascher bei dem Ziele ankommt. Anfänglich müht sich jeder ab, + die Formen in hergebrachter Weise zu gliedern und die 'guten Arten' + herauszulesen. Mit der Erweiterung des Gesichtskreises und mit der + Vermehrung der Anschauungen aber schwindet auch immer mehr der + Boden unter den Füssen, die bisher für unverrückbar gehaltenen + Grenzen der gut geglaubten Arten stellen sich als eine der Natur + angelegte Zwangsjacke heraus, die Uebcrzeugung, dass die Grenzen, + welche wir ziehen, eben nur künstliche sind, gewinnt immer mehr und + mehr die Oberhand, und wer nicht gerade zu den hartgesottenen + Eigensinnigen gehört, und wer die Wahrheit höher stellt als das + starre Festhalten an seinen früheren Ansichten, geht schliesslich + bewusst oder unbewusst in das Lager derjenigen über, in welchem + auch ich mir ein bescheidenes Plätzchen aufgesucht habe." + +By these "hard-boiled" botanists he means those who entertain the +traditional notion of a species as an assemblage of definite +characters, always and everywhere associated together. This notion +(Artsbeständigkeit) must be entirely abandoned. Summarizing Kerner's +facts for their general results we find that his extensive +investigations have proved that in his numberless kinds of European +plants the following relations frequently obtain. Supposing that there +are two or more allied species, A and B, then A' and B' may be taken to +represent their respective types as found in some particular area. It +does not signify whether A' and B' are geographically remote from, or +close to, A and B; the point is that, whether in respect of temperature, +altitude, moisture, character of soil, &c., there is some difference in +the conditions of life experienced by the plants growing at the +different places. Now, in numberless plants it is found that the typical +or constant peculiarities of A' differ more from those of A than they do +from those of B; while, conversely, the characters of A' may bear more +resemblance to those of B' than they do to those of A--on account of +such characters being due to the same external causes in both cases. The +consequence is that A' might more correctly be classified with B', or +_vice versa_. Another consequence is that whether A and B, or A' and B', +be recorded as the "good species" usually depends upon which has +happened to have been first described. + +Such a mere abstract of Kerner's general results, however, can give no +adequate idea of their cogency: for this arises from the number of +species in which specific characters are thus found to change, and even +to _interchange_, with different conditions of life. Thus he gives an +amusing parable of an ardent young botanist, Simplicius, who starts on a +tour in the Tyrol with the works of the most authoritative systematists +to assist him in his study of the flora. The result is that Simplicius +becomes so hopelessly bewildered in his attempts at squaring their +diagnostic descriptions with the facts of nature, that he can only +exclaim in despair--"Sonderbare Flora, diese tirolische, in welcher so +viele characteristische Pflanzen nur schlechte Arten, oder gar noch +schlechter als schlechte Arten, sind." Now, in giving illustrations of +this young man's troubles, Kerner fills five or six pages with little +else than rows of specific names. + +Upon the whole, Kerner concludes that the more the subject is studied, +the more convinced must the student become that all distinction between +species as "good" and "bad" vanishes. In other words, the more that our +knowledge of species and of their diagnostic characters increases, the +more do we find that "bad species" multiply at the expense of "good +species"; so that eventually we must relinquish the idea of "good +species" altogether. Or, conversely stated, we must agree to regard as +equally "good species" any and every assemblage of individuals which +present the same peculiarities: provided that these peculiarities do not +rise to a generic value, they equally deserve to be regarded as +"specific characters," no matter how trivial, or how local, they may be. +In fact, he goes so far as to say that when, as a result of experiments +in transplantation from one set of physical conditions to another, +seedlings are found to present any considerable and constant change in +their specific characters, these seedlings are no less entitled to be +regarded as a "good species" than are the plants from which they have +been derived. Probably few systematists will consent to go quite so far +as this; but the fact that Kerner has been led deliberately to propound +such a statement as a result of his wide observations and experiments is +about as good evidence as possible on the points with which we are here +concerned. For even Simplicius would hardly be quite so simple as to +suppose that each one of all the characters which he observes in his +"remarkable flora," so largely composed of "bad or even worse than bad +species," is of utilitarian significance. + +Be it noted, however, that I am not now expressing my own opinion. There +are weighty reasons against thus identifying climatic variations with +good species--reasons which will be dealt with in the next chapter. +Kerner does not seem to appreciate the weight of these reasons, and +therefore I do not call him as a witness to the subject as a whole; but +only to that part of it which has to do with the great and general +importance of climatic variability in relation to diagnostic work. And +thus far his testimony is fully corroborated by every other botanist who +has ever attended to the subject. Therefore it does not seem worth while +to quote further authorities in substantiation of this point, such as +Gärtner, De Candolle, Nägeli, Peter, Jordan, &c. For nowadays no one +will dispute the high generality and the frequently great extent of +climatic variation where the vegetable kingdom is concerned. Indeed, it +may fairly be doubted whether there is any one species of plant, whose +distribution exposes it to any considerable differences in its external +conditions of life, which does not present more or less considerable +differences as to its characters in different parts of its range. The +principal causes of such climatic variation appear to be the chemical, +and, still more, the mechanical nature of soil; temperature; intensity +and diurnal duration of light in spring and summer; moisture; presence +of certain salts in the air and soil of marine plants, or of plants +growing near mineral springs; and sundry other circumstances of a more +or less unknown character. + +Before closing these remarks on climatic variation in the vegetable +kingdom, prominent attention must be directed to a fact of broad +generality and, in relation to our present subject, of considerable +importance. This is that the same external causes very frequently +produce the same effects in the way of specific change throughout large +numbers of _unrelated_ species--i.e. species belonging to different +genera, families, and orders. Moreover, throughout all these unrelated +species, we can frequently trace a uniform correlation between the +degrees of change and the degrees to which they have been subjected to +the causes in question. + +As examples, all botanists who have attended to the subject are struck +by the similarity of variation presented by different species growing on +the same soils, altitudes, latitudes, longitudes, and so forth. Plants +growing on chalky soils, when compared with those growing on richer +soils, are often more thickly covered with down, which is usually of a +white or grey colour. Their leaves are frequently of a bluish-green +tint, more deeply cut, and less veined, while their flowers tend to be +larger and of a lighter tint. There are similarly constant differences +in other respects in varieties growing on sundry other kinds of soils. +Sea-salt has the general effect, on many different kinds of plants, of +producing moist fleshy leaves, and red tints. Experiments in +transplantation have shown that these changes may be induced +artificially; so there can be no doubt as to its being this that and the +other set of external conditions which produces them in nature. Again, +dampness causes leaves to become smoother, greener, less cut, and the +flowers to become darker; while dryness tends to produce opposite +effects. I need not go on to specify the particular results on all kinds +of plants of altitude, latitude, longitude, and so forth. For we are +concerned only with the fact that these two correlations may be regarded +as general laws appertaining to the vegetable kingdom--namely, (A) that +the same external causes produce similar varietal effects in numerous +unallied species of plants; and, (B) that the more these species are +exposed to such causes the greater is the amount of varietal effect +produced--so that, for instance, on travelling from latitude to +latitude, longitude to longitude, altitude to altitude, &c., we may see +greater and greater degrees of such definite and more or less common +varietal changes affecting the unallied species in question. Now these +general laws are of importance for us, because they prove unequivocally +that it is the direct action of external conditions of life which +produce climatic variations of specific types. And, taken in connexion +with the results of experiments in transplantation (which in a single +generation may yield variations similar to those found in nature under +similar circumstances), these general laws still further indicate that +climatic variations are "indifferent" variations. In other words, we +find that changes of specific characters are of widespread occurrence in +the vegetable kingdom, that they are constantly and even proportionally +related to definite external circumstances, but yet that, in as far as +they are climatic, they cannot be attributed to the agency of natural +selection[109]. + + [109] Since the above paragraphs have been in type, the Rev. G. + Henslow has published his Linnaean Society papers which are + mentioned in the introductory chapter, and which deal in more + detail with this subject, especially as regards the facies of + desert floras. + +Turning next to animals, it may first be observed that climatic +conditions do not appear to exercise an influence either so general or +so considerable as in the case of plants. Nevertheless, although these +influences are relatively more effective in the vegetable kingdom than +they are in the animal, absolutely considered they are of high +generality and great importance even in the latter. But as this fact is +so well recognized by all zoologists, it will be needless to give more +than a very few illustrations. Indeed, throughout this discussion on +climatic influences my aim is merely to give the general reader some +idea of their importance in regard to systematic natural history; and, +therefore, such particular cases as are mentioned are selected only as +samples of whole groups of cases more or less similar. + +With regard to animals, then, we may best begin by noticing that, just +as in the case of plants, there is good evidence of the same external +causes producing the same effects in multitudes of species belonging to +different genera, families, orders, and even classes. Moreover, we are +not without similarly good evidence of _degrees_ of specific change +taking place in correlation with _degrees_ of climatic change, so that +we may frequently trace a gradual progress of the former as we advance, +say, from one part of a large continent to another. Instances of these +correlations are not indeed so numerous in the animal kingdom as they +are in the vegetable. Nevertheless they are amply sufficient for our +present purposes. + +For example, Mr. Allen has studied in detail changes of size and colour +among birds and mammals on the American continent; and he finds a +wonderfully close sliding scale of both, corresponding stage by stage +with gradual changes of climate. Very reasonably he attributes this to +the direct influence of climatic conditions, without reference to +natural selection--as does also Mr. Gould with reference to similar +facts which he has observed among the birds of Australia. Against this +view Mr. Wallace urges, "that the effects are due to the greater or less +need of protection." But it is difficult to believe that such can be the +case where so innumerable a multitude of widely different species are +concerned--presenting so many diverse habits, as well as so many +distinct habitats. Moreover, the explanation seems incompatible with the +_graduated_ nature of the change, and also with the fact that not only +colouration but size, is implicated. + +We meet with analogous facts in butterflies. Thus _Lycaena agestis_ not +only presents seasonal variations, (A) and (B); but while (A) and (B) +are respectively the winter and summer forms in Germany, (B) and (C) are +the corresponding forms in Italy. Therefore, (B) is in Germany the +summer form, and in Italy the winter form--the German winter form (A) +being absent in Italy, while the Italian summer form (C) is absent in +Germany. Probably these facts are due to differences of temperature in +the two countries, for experiments have shown that when pupae of sundry +species of moths and butterflies are exposed to different degrees of +temperature, the most wonderful changes of colour may result in the +insects which emerge. The remarkable experiments of Dorfmeister and +Weismann in relation to this subject are well known. More recently Mr. +Merrifield has added to their facts, and concludes that the action of +cold upon the pupae--and also, apparently, upon the larvae--has a +tendency to produce dark hues in the perfect insect[110]. + + [110] _Trans. Entom. Soc._ 1889, part i. p. 79 _et seq._ + +But, passing now from such facts of climatic variations over wide areas +to similar facts within small areas, in an important _Memoir on the Cave +Fauna of North America_, published a few years ago by the American +Academy of Sciences, it is stated:-- + + "As regards change of colour, we do not recall an exception to the + general rule that all cave animals are either colourless or nearly + white, or, as in the case of Arachnida and Insects, much paler than + their out-of-door relatives." + +Now, when we remember that these cave faunas comprise representatives of +nearly all classes of the animal kingdom, it becomes difficult, if not +impossible, to imagine that so universal a discharge of colouring can be +due to natural selection. It must be admitted that the only way in which +natural selection could act in this case would be indirectly through the +principle of correlation. There being no light in the caves, it can be +of no advantage to the animals concerned that they should lose their +colour for the sake of protection, or for any other reason of a +similarly direct kind. Therefore, if the loss of colour is to be +ascribed to natural selection, this can only be done by supposing that +natural selection has here acted indirectly through the principle of +correlation. There is evidence to show that elsewhere modification or +loss of colour is in some cases brought about by natural selection, on +account of the original colour being correlated with certain +physiological characters (such as liability to particular diseases, +&c.); so that when natural selection operates directly upon these +physiological characters, it thereby also operates indirectly upon the +correlated colours. But to suppose that this can be the explanation of +the uniform diminution of colour in all inhabitants of dark caves would +be manifestly absurd. If there were only one class of animals in these +caves, such as Insects, it might be possible to surmise that their +change of colour is due to natural selection acting directly upon their +physiological constitutions, and so indirectly upon their colours. But +it would be absurd to suppose that such can be the explanation of the +facts, when these extend in so similar a manner over so many scores of +species belonging to such different types of animal life. + +With more plausibility it might be held that the universal discharge of +colour in these cave-faunas is due, not to the presence, but to the +absence of selection--i. e. to the cessation of selection, or panmixia. +But against this--at all events as a full or general explanation--lie +the following facts. First, in the case of Proteus--which has often been +kept for the purposes of exhibition &c., in tanks--the skin becomes dark +when the animal is removed from the cave and kept in the light. +Secondly, deep-sea faunas, though as much exposed as the cave-faunas, to +the condition of darkness, are not by any means invariably colourless. +On the contrary, they frequently present brilliant colouration. Thus it +is evident that if panmixia be suggested in explanation of the +discharge of colouring in cave-faunas, the continuance of colour in +deep-sea faunas appears to show the explanation insufficient. Thirdly, +according to my view of the action of panmixia as previously explained, +no _total_ discharge of colouration is likely to be caused by such +action alone. At most the bleaching as a result of the mere withdrawal +of selection would proceed only to some comparatively small extent. +Fourthly, Mr. Packard in the elaborate _Memoir on Cave Fauna_, already +alluded to, states that in some of the cases the phenomena of bleaching +appear to have been induced within very recent times--if not, indeed, +within the limits of a single generation. Should the evidence in support +of this opinion prove trustworthy, of course in itself it disposes of +any suggestion either of the presence or the absence of natural +selection as concerned in the process. + +Nevertheless, I myself think it inevitable that to some extent the +cessation of selection must have helped in discharging the colour of +cave faunas; although for the reasons now given it appears to me that +the main causes of change must have been of that direct order which we +understand by the term climatic. + +As regards dogs, the Rev. E. Everest found it impossible to breed Scotch +setters in India true to their type. Even in the second generation no +single young dog resembled its parents either in form or shape. "Their +nostrils were more contracted, their noses more pointed, their size +inferior, and their limbs more slender[111]." Similarly on the coast of +New Guinea, Bosman says that imported breeds of dogs "alter strangely; +their ears grow long and stiff like those of foxes, to which colour they +also incline ... and in three or four broods their barking turns into a +howl[112]." + + [111] _Variation_, &c. vol. i. p. 40. + + [112] _Variation_, &c. vol. i. p. 40. + +Darwin gives numerous facts showing the effects of climate on horses, +cattle, and sheep, in altering, more or less considerably, the +characters of their ancestral stocks. He also gives the following +remarkable case with regard to the rabbit. Early in the fifteenth +century a common rabbit and her young ones were turned out on the island +of Porto Santo, near Madeira. The feral progeny now differ in many +respects from their parent stock. They are only about one-third of the +weight, present many differences in the relative sizes of different +parts, and have greatly changed in colour. In particular, the black on +the upper surface of the tail and tips of the ears, which is so constant +in all other wild rabbits of the world as to be given in most works as a +specific character, has entirely disappeared. Again, "the throat and +certain parts of the under surface, instead of being pure white, are +generally grey or leaden colour," while the upper surface of the whole +body is redder than in the common rabbit. Now, what answer have our +opponents to make to such a case as this? Presumably they will answer +that the case simply proves the action of natural selection during the +best part of 400 years on an isolated section of a species. Although we +cannot say of what use all these changes have been to the rabbits +presenting them, nevertheless we _must_ believe that they have been +produced by natural selection, and therefore _must_ present some hidden +use to the isolated colony of rabbits thus peculiarly situated. Four +centuries is long enough to admit of natural selection effecting all +these changes in the case of so rapidly breeding an animal as the +rabbit, and therefore it is needless to look further for any explanation +of the facts. Such, I say, is presumably the answer that would be given +by the upholders of natural selection as the only possible cause of +specific change. But now, in this particular case it so happens that the +answer admits of being conclusively negatived, by showing that the great +assumption on which it reposes is demonstrably false. For Darwin +examined two living specimens of these rabbits which had recently been +sent from Porto Santo to the Zoological Gardens, and found them coloured +as just described. Four years afterwards the dead body of one of them +was sent to him, and then he found that the following changes had taken +place. "The ears were plainly edged, and the upper surface of the tail +was covered with blackish-grey fur, and the whole body was much less +red; so that under the English climate this individual rabbit has +recovered the proper colour of its fur in rather less than four years!" + +Mr. Darwin adds:-- + + "If the history of these Porto Santo rabbits had not been known, + most naturalists, on observing their much reduced size, their + colour, reddish above and grey beneath, their tails and ears not + tipped with black, would have ranked them as a distinct species. + They would have been strongly confirmed in this view by seeing them + alive in the Zoological Gardens, and hearing that they refused to + couple with other rabbits. Yet this rabbit, which there can be + little doubt would thus have been ranked as a distinct species, as + certainly originated since the year 1420[113]." + + [113] _Variation_, &c. vol. i. p. 120. + +Moreover, it certainly originated as a direct result of climatic +influences, independent of natural selection; seeing that, as soon as +individual members of this apparently new species were restored to their +original climate, they recovered their original colouration. + +As previously remarked, it is, from the nature of the case, an +exceedingly difficult thing to prove in any given instance that natural +selection has not been the cause of specific change, and so finally to +disprove the assumption that it must have been. Here, however, on +account of historical information, we have a crucial test of the +validity of this assumption, just as we had in the case of the niata +cattle; and, just as in their case, the result is definitely and +conclusively to overturn the assumption. If these changes in the Porto +Santo rabbits had been due to the gradual influence of natural selection +guided by inscrutable utility, it is simply impossible that the same +individual animals, in the course of their own individual life-times, +should revert to the specific characters of their ancestral stock on +being returned to the conditions of their ancestral climate. Therefore, +unless any naturalist is prepared to contradict Darwin's statement that +the changes in question amount to changes of specific magnitude, he can +find no escape from the conclusion that distinctions of specific +importance may be brought about by changes of habitat alone, without +reference to utility, and therefore independently of natural selection. + + +II. _Food._ + +Although, as yet, little is definitely known on the subject, there can +be no doubt that in the case of many animals differences of food induce +differences of colour within the life-time of individuals, and therefore +independently of natural selection. + +Thus, sundry definite varieties of the butterfly _Euprepia caja_ can be +reared according to the different nourishment which is supplied to the +caterpillar; and other butterflies are also known on whose colouring and +markings the food of the caterpillar has great influence[114]. + + [114] See especially, Koch, _Die Raupen und Schmetterling der + Wetterau_, and _Die Schmetterling des Südwestlichen + Deutschlands_, whose very remarkable results of numerous and + varied experiments are epitomized by Eimer, _Organic + Evolution_, Eng. Trans. pp. 147-153; also Poulton, _Trans. + Entom. Soc._ 1893. + +Again, I may mention the remarkable case communicated to Darwin by +Moritz Wagner, of a species of _Saturnia_, some pupae of which were +transported from Texas to Switzerland in 1870. The moths which emerged +in the following year were like the normal type in Texas. Their young +were supplied with leaves of _Juglans regia_, instead of their natural +food, _J. nigra_; and the moths into which these caterpillars changed +were so different from their parents, both in form and colour, "that +they were reckoned by entomologists as a distinct species[115]." + + [115] Mivart, _On Truth_, p. 378. + +With regard to mollusks, M. Costa tells us that English oysters, when +turned down in the Mediterranean, "_rapidly_ became like the true +Mediterranean oyster, altered their manner of growth, and formed +prominent diverging rays." This is most probably due to some change of +food. So likewise may be the even more remarkable case of _Helix +nemoralis_, which was introduced from Europe to Virginia a few years +ago. Under the new conditions it varied to such an extent that up to +last year no less than 125 varieties had been discovered. Of these 67, +or more than half, are new--that is, unknown in the native continent of +the species[116]. + + [116] Cockerell, _Nature_, vol. xli. p. 393. + +In the case of Birds, the Brazilian parrot _Chrysotis festiva_ changes +the green in its feathers to red or yellow, if fed on the fat of certain +fishes; and the Indian Lori has its splendid colouring preserved by a +peculiar kind of food (Wallace). The Bullfinch is well known to turn +black when fed on hemp seeds, and the Canary to become red when fed on +cayenne pepper (Darwin). Starting from these facts, Dr. Sauermann has +recently investigated the subject experimentally; and finds that not +only finches, but likewise other birds, such as fowls, and pigeons, are +subject to similar variations of colour when fed on cayenne pepper; but +in all cases the effect is produced only if the pepper is given to the +young birds before their first moult. Moreover, he finds that a moist +atmosphere facilitates the change of colour, and that the ruddy hue is +discharged under the influence either of sunlight or of cold. Lastly, he +has observed that sundry other materials such as glycerine and aniline +dyes, produce the same results; so there can be no doubt that organic +compounds probably occur in nature which are capable of directly +affecting the colours of plumage when eaten by birds. Therefore the +presence of such materials in the food-stuffs of birds occupying +different areas may very well in many cases determine differences of +colouration, which are constant or stable so long as the conditions of +their production are maintained. + + +III. _Sexual Selection._ + +Passing on now to causes of specific change which are internal, or +comprised within the organisms themselves, we may first consider the +case of Sexual Selection. + +Mr. Wallace rejects the theory of sexual selection _in toto_, and +therefore nothing that can be said under this head would be held by him +to be relevant. Many naturalists, however, believe that Darwin was right +in the large generalization which he published under this title; and in +so far as any one holds that sexual selection is a true cause of +specific modification, he is obliged to believe that innumerable +specific characters--especially in birds and mammals--have been produced +without reference to utility (other, of course, than utility for sexual +purposes), and therefore without reference to natural selection. This is +so obvious that I need not pause to dilate upon it. One remark, however, +may be useful. Mr. Wallace is able to make a much more effective use of +his argument from "necessary instability" when he brings it against the +Darwinian doctrine of sexual selection, than he does when he brings it +against the equally Darwinian doctrine of specific characters in general +not being all necessarily due to natural selection. In the latter case, +it will be remembered, he is easily met by showing that the causes of +specific change other than natural selection, such as food, climate, +&c., may be quite as general, persistent, and uniform, as natural +selection itself; and therefore in this connexion Mr. Wallace's argument +falls to the ground. But the argument is much more formidable as he +brings it to bear against the theory of sexual selection. Here he asks, +What is there to guarantee the uniformity and the constancy of feminine +taste with regard to small matters of embellishment through thousands of +generations, and among animals living on extensive areas? And, as we +have seen in Part 1, it is not easy to supply an answer. Therefore this +argument from the "necessary instability of character" is of +immeasurably greater force as thus applied against Darwin's doctrine of +sexual selection, than it is when brought against his doctrine that all +specific characters need not necessarily be due to natural selection. +Therefore, also, if any one feels disposed to attach the smallest degree +of value to this argument in the latter case, consistency will require +him to allow that in the former case it is simply overwhelming, or in +itself destructive of the whole theory of sexual selection. And, +conversely, if his belief in the theory of sexual selection can survive +collision with this objection from instability, he ought not to feel any +tremor of contact when the objection is brought to bear against his +scepticism regarding the alleged utility of all specific characters. For +assuredly no specific character which is apparent to our eyes can be +supposed to be so refined and complex (and therefore so presumably +inconstant and unstable), as are those minute changes of cerebral +structure on which a psychological preference for all the refined +shadings and many pigments of a complicated pattern must be held +ultimately to depend. For this reason, then, as well as for those +previously adduced, if any one agrees with Darwin in holding to the +theory of sexual selection notwithstanding this objection from the +necessary instability of unuseful embellishments, _a fortiori_ he ought +to disregard the objection altogether in its relation to useless +specific characters of other kinds. + +But quite apart from this consideration, which Mr. Wallace and his +followers may very properly say does not apply to them, let us see what +they themselves have made of the facts of secondary sexual +characters--which, of course, are for the most part specific +characters--in relation to the doctrine of utility. + +Mr. Wallace himself, in his last work, quotes approvingly a letter which +he received in 1869 from the Rev. O Pickard-Cambridge, as follows:-- + + "I myself doubt that particular application of the Darwinian theory + which attributes male peculiarities of form, structure, colour, and + ornament to female appetency or predilection. There is, it seems to + me, undoubtedly something in the male organization of a special and + sexual nature, which, of its own vital force, develops the + remarkable male peculiarities so commonly seen, _and of no + imaginable use to that sex_. In as far as these peculiarities show + a great vital power, they point out to us the finest and strongest + individuals of the sex, and show us which of them would most + certainly appropriate to themselves the best and greatest number of + females, and leave behind them the strongest and greatest number of + progeny. And here would come in, as it appears to me, the proper + application of Darwin's theory of Natural Selection; _for the + possessors of greatest vital power being those most frequently + produced and reproduced, the external signs of it would go on + developing in an ever increasing exaggeration_, only to be checked + where it became really detrimental in some respect or other to the + individual[117]." + + [117] _Darwinism_, pp.[typo: period missing in scan] 296-7: italics + mine. + +Here then the idea is, as more fully expressed by Mr. Wallace in the +context, that all the innumerable, frequently considerable, and +generally elaborate "peculiarities of form, structure, colour, and +ornament," which Darwin attributed to sexual selection, are really due +to "the laws of growth." Diverse, definite, and constant though these +specific peculiarities be, they are all but the accidental or +adventitious accompaniments of "vigour," or "vital power," due to +natural selection. Now, without waiting to dispute this view, which has +already been dealt with in the chapter on Sexual Selection in Part I, it +necessarily follows that "a large proportional number of specific +characters," which, while presenting "no imaginable use," are very much +less remarkable, less considerable, less elaborate, &c., must likewise +be due to this "correlation with vital power." But if the principle of +correlation is to be extended in this vague and general manner, it +appears to me that the difference between Mr. Wallace and myself, with +respect to the principle of utility, is abolished. For of course no one +will dispute that the prime condition to the occurrence of "specific +characters," whether useful or useless, is the existence of some form +which has been denominated a "species" to present them; and this is +merely another way of saying that such characters cannot arise except in +correlation with a general fitness due to natural selection. Or, to put +the case in Mr. Wallace's own words--"This development [of useless +specific characters] will necessarily proceed by the agency of natural +selection [as a necessary condition] _and the general laws which +determine the production of colour and of ornamental appendages_." The +case, therefore, is just the same as if one were to say, for example, +that all the ailments of animals and plants proceed from correlation +with life (as a necessary condition), "and the general laws which +determine the production" of ill-health, or of specific disease. In +short, the word "correlation" is here used in a totally different sense +from that in which it is used by Darwin, and in which it is elsewhere +used by Wallace for the purpose of sustaining his doctrine of specific +characters as necessarily useful. To say that a useless character A is +correlated with a useful one B, is a very different thing from saying +that A is "correlated with vital power," or with the general conditions +to the existence of the species to which it belongs. So far as the +present discussion is concerned, no exception need be taken to the +latter statement. For it simply surrenders the doctrine against which I +am contending. + + +IV. _Isolation._ + +It is the opinion of many naturalists who are well entitled to have an +opinion upon the subject, that, in the words of Mr. Dixon, "Isolation +can preserve a non-beneficial as effectually as natural selection can +preserve a beneficial variation[118]." The ground on which this doctrine +rests is thus clearly set forth by Mr. Gulick:--"The fundamental cause +of this seems to lie in the fact that no two portions of a species +possess exactly the same average characters; and, therefore, that the +initial differences are for ever reacting on the environment and on each +other in such a way as to ensure increasing divergence in each +generation, as long as the individuals of the two groups are kept from +intergenerating[119]." In other words, as soon as a portion of a species +is separated from the rest of that species, so that breeding between the +two portions is no longer possible, the general average of characters in +the separated portion not being in all respects precisely the same as it +is in the other portion, the result of in-breeding among all individuals +of the separated portion will eventually be different from that which +obtains in the other portion; so that, after a number of generations, +the separated portion may become a distinct species from the effect of +isolation alone. Even without the aid of isolation, any original +difference of average characters may become, as it were, magnified in +successive generations, provided that the divergence is not harmful to +the individuals presenting it, and that it occurs in a sufficient +proportional number of individuals not to be immediately swamped by +intercrossing. For, as Mr. Murphy has pointed out, in accordance with +Delboeuf's law, "if, in any species, a number of individuals, bearing a +ratio not infinitely small to the entire number of births, are in every +generation born with a particular variation which is neither beneficial +nor injurious, and if it be not counteracted by reversion, then the +proportion of the new variety to the original form will increase till it +approaches indefinitely near to equality[120]." Now even Mr. Wallace +himself allows that this must be the case; and thinks that in these +considerations we may find an explanation of the existence of certain +definite varieties, such as the melanic form of the jaguar, the brindled +or ring-eyed guillemot, &c. But, on the other hand, he thinks that such +varieties must always be unstable, and continually produced in varying +proportions from the parent forms. We need not, however, wait to dispute +this arbitrary assumption, because we can see that it fails, even as an +assumption, in all cases where the superadded influence of isolation is +concerned. Here there is nothing to intercept the original tendency to +divergent evolution, which arises directly out of the initially +different average of qualities presented by the isolated section of the +species, as compared with the rest of that species[121]. + + [118] _Nature_, vol. xxxiii. p. 100. + + [119] _Divergent Evolution through Cumulative Segregation_, Linn. + Journ. Zoology, vol. xx. p. 215. + + [120] _Habit and Intelligence_, p. 241. + + [121] Allusion may here again be made to the case of the niata + cattle. For here is a case where a very extreme variety is + certainly not unstable, nor produced in varying proportions + from the parent form. Moreover, as we have seen in the + preceding chapter, this almost monstrous variety most probably + originated as an individual sport--being afterwards maintained + and multiplied for a time by artificial selection. Now, + whether or not this was the case, we can very well see that it + may have been. Hence it will serve to illustrate another + possibility touching the origin and maintenance of useless + specific characters. For what is to prevent an individual + congenital variation of any kind (provided it be not harmful) + from perpetuating itself as a "varietal," and eventually, + should offspring become sufficiently numerous, a "specific + character"? There is nothing to prevent this, save panmixia, + or the presence of free intercrossing. But, as we shall see in + the next division of this treatise, there are in nature many + forms of isolation. Hence, as often as a small number of + individuals may have experienced isolation in any of its + forms, opportunity for perpetuation will have been given to + any congenital variations which may happen to arise. Should + any of these be pronounced variations, it would afterwards be + ranked as a specific character. I do not myself think that + this is the way in which indifferent specific characters + _usually_ originate. On the contrary, I believe that their + origin is most frequently due to the influence of isolation on + the average characters of the whole population, as briefly + stated in the text. But here it seems worth while to notice + this possibility of their occasionally arising as merely + individual variations, afterwards perpetuated by any of the + numerous isolating conditions which occur in nature. For, if + this can be the case with a varietal form so extreme as to + border on the monstrous, much more can it be so with such + minute differences as frequently go to constitute specific + distinctions. It is the business of species-makers to search + out such distinctions, no matter how trivial, and to record + them as "specific characters." Consequently, wherever in + nature a congenital variation happens to arise, and to be + perpetuated by the force of heredity alone under any of the + numerous forms of isolation which occur in nature, there will + be a case analogous to that of the niata cattle. + +As we shall have to consider the important principle of isolation more +fully on a subsequent occasion, I need not deal with it in the present +connexion, further than to remark that in this principle we have what +appears to me a full and adequate condition to the rise and continuance +of specific characters which need not necessarily be adaptive +characters. And, when we come to consider the facts of isolation more +closely, we shall find superabundant evidence of this having actually +been the case. + + +V. _Laws of Growth._ + +Under this general term Darwin included the operation of all unknown +causes internal to organisms leading to modifications of form or +structure--such modifications, therefore, appearing to arise, as he says +"spontaneously," or without reference to utility. That he attributed no +small importance to the operation of these principles is evident from +the last edition of the _Origin of Species_. But as these "laws of +growth" refer to causes confessedly unknown, I will not occupy space by +discussing this division of our subject--further than to observe that, +as we shall subsequently see, many of the facts which fall under it are +so irreconcilably adverse to the Wallacean doctrine of specific +characters as universally adaptive, that in the face of them Mr. Wallace +himself appears at times to abandon his doctrine _in toto_. + + + + +CHAPTER IX. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_continued_). + + +It must have appeared strange that hitherto I should have failed to +distinguish between "true species" and merely "climatic varieties." But +it will conduce to clearness of discussion if we consider our subject +point by point. Therefore, having now given a fair statement of the +facts of climatic variation, I propose to deal with their theoretical +implications--especially as regards the distinction which naturalists +are in the habit of drawing between them and so-called true species. + +First of all, then, what is this distinction? Take, for example, the +case of the Porto Santo rabbits. To almost every naturalist who reads +what has been said touching these animals, it will have appeared that +the connexion in which they are adduced is wholly irrelevant to the +question in debate. For, it will be said that the very fact of the +seemingly specific differentiation of these animals having proved to be +illusory when some of them were restored to their ancestral conditions, +is proof that their peculiar characters are not specific characters; but +only what Mr. Wallace would term "individual characters," or variations +that are not _inherited_. And the same remark applies to all the other +cases which have been adduced to show the generality and extent of +climatic variation, both in other animals and also in plants. Why, then, +it will be asked, commit the absurdity of adducing such cases in the +present discussion? Is it not self-evident that however general, or +however considerable, such merely individual, or non-heritable, +variations may be, they cannot possibly have ever had anything to do +with the origin of _species_? Therefore, is it not simply preposterous +to so much as mention them in relation to the question touching the +utility of specific characters? + +Well, whether or not it is absurd and preposterous to consider climatic +variations in connexion with the origin of species, will depend, and +depend exclusively, on what it is that we are to understand by a +species. Hitherto I have assumed, for the sake of argument, that we all +know what is meant by a species. But the time has now come for showing +that such is far from being the case. And as it would be clearly absurd +and preposterous to conclude anything with regard to specific characters +before agreeing upon what we mean by a character as specific, I will +begin by giving all the logically possible definitions of a species. + +1. _A group of individuals descended by way of natural generation from +an originally and specially created type._ + +This definition may be taken as virtually obsolete. + +2. _A group of individuals which, while fully fertile_ inter se, _are +sterile with all other individuals--or, at any rate, do not generate +fully fertile hybrids._ + +This purely physiological definition is not nowadays entertained by any +naturalist. Even though the physiological distinction be allowed to +count for something in otherwise doubtful cases, no systematist would +constitute a species on such grounds alone. Therefore we need not +concern ourselves with this definition, further than to observe that it +is often taken as more or less supplementary to each of the following +definitions. + +3. _A group of individuals which, however many characters they share +with other individuals, agree in presenting one or more characters of a +peculiar kind, with some certain degree of distinctness._ + +In this we have the definition which is practically followed by all +naturalists at the present time. But, as we shall presently see more +fully, it is an extremely lax definition. For it is impossible to +determine, by any fixed and general rule, what degree of distinctness on +the part of peculiar characters is to be taken as a uniform standard of +specific separation. So long as naturalists believed in special +creation, they could feel that by following this definition (3) they +were at any rate doing their best to tabulate very real distinctions in +nature--viz. between types as originally produced by a supernatural +cause, and as subsequently more or less modified (i.e. within the limits +imposed by the test of cross-fertility) by natural causes. But +evolutionists are unable to hold any belief in such real distinctions, +being confessedly aware that all distinctions between species and +varieties are purely artificial. So to speak, they well know that it is +they themselves who create species, by determining round what degrees of +differentiation their diagnostic boundaries shall be drawn. And, seeing +that these degrees of differentiation so frequently shade into one +another by indistinguishable stages (or, rather, that they _always_ do +so, unless intermediate varieties have perished), modern naturalists are +well awake to the impossibility of securing any approach to a uniform +standard of specific distinction. On this account many of them feel a +pressing need for some firmer definition of a species than this +one--which, in point of fact, scarcely deserves to be regarded as a +definition at all, seeing that it does not formulate any definite +criterion of specific distinctness, but leaves every man to follow his +own standards of discrimination. Now, as far as I can see, there are +only two definitions of a species which will yield to evolutionists the +steady and uniform criterion required. These two definitions are as +follows. + +4. _A group of individuals which, however many characters they share +with other individuals, agree in presenting one or more characters of a +peculiar and hereditary kind, with some certain degree of distinctness._ + +It will be observed that this definition is exactly the same as the last +one, save in the addition of the words "and hereditary." But, it is +needless to say, the addition of these words is of the highest +importance, inasmuch as it supplies exactly that objective and rigid +criterion of specific distinctness which the preceding definition lacks. +It immediately gets rid of the otherwise hopeless wrangling over species +as "good" and "bad," or "true" and "climatic," of which (as we have +seen) Kerner's essay is such a remarkable outcome. Therefore +evolutionists have more and more grown to lay stress on the hereditary +character of such peculiarities as they select for diagnostic features +of specific distinctness. Indeed it is not too much to say that, at the +present time, evolutionists in general recognize this character as, +theoretically, indispensable to the constitution of a species. But it is +likewise not too much to say that, practically, no one of our systematic +naturalists has hitherto concerned himself with this matter. At all +events, I do not know of any who has ever taken the trouble to ascertain +by experiment, with regard to any of the species which he has +constituted, whether the peculiar characters on which his diagnoses have +been founded are, or are not, hereditary. Doubtless the labour of +constituting (or, still more, of _re_-constituting) species on such a +basis of experimental inquiry would be insuperable; while, even if it +could be accomplished, would prove undesirable, on account of the chaos +it would produce in our specific nomenclature. But, all the same, we +must remember that this nomenclature as we now have it--and, therefore, +the partitioning of species as we have now made them--has no reference +to the criterion of heredity. Our system of distinguishing between +species and varieties is not based upon the definition which we are now +considering, but upon that which we last considered--frequently coupled, +to some undefinable extent, with No. 2. + +5. There is, however, yet another and closer definition, which may be +suggested by the ultra-Darwinian school, who maintain the doctrine of +natural selection as the only possible cause of the origin of species, +namely:-- + +_A group of individuals which, however many characters they share with +other individuals, agree in presenting one or more characters of a +peculiar, hereditary, and adaptive kind, with some certain degree of +distinctness._ + +Of course this definition rests upon the dogma of utility as a necessary +attribute of characters _quâ_ specific--i.e. the dogma against which the +whole of the present discussion is directed. Therefore all I need say +with reference to it is, that at any rate it cannot be adduced in any +argument where the validity of its basal dogma is in question. For it +would be a mere begging of this question to argue that every species +must present at least one peculiar and adaptive character, because, +according to definition, unless an organic type does present at least +one such character, it is not a specific type. Moreover, and quite apart +from this, it is to be hoped that naturalists as a body will never +consent to base their diagnostic work on what at best must always be a +highly speculative extension of the Darwinian theory. While, lastly, if +they were to do so with any sort of consistency, the precise adaptation +which each peculiar character subserves, and which because of this +adaptation is constituted a character of specific distinction, would +have to be determined by actual observation. For no criterion of +specific distinction could be more vague and mischievous than this one, +if it were to be applied on grounds of mere inference that such and such +a character, because seemingly constant, must "necessarily" be either +useful, vestigial, or correlated. + +Such then, as far as I can see, are all the definitions of a species +that are logically possible[122]. Which of them is chosen by those who +maintain the necessary usefulness of all specific characters? Observe, +it is for those who maintain this doctrine to choose their definition: +it is not for me to do so. My contention is, that the term does not +admit of any definition sufficiently close and constant to serve as a +basis for the doctrine in question--and this for the simple reason that +species-makers have never agreed among themselves upon any criterion of +specific distinction. My opponents, on the other hand, are clearly bound +to take an opposite view, because, unless they suppose that there is +some such definition of a species, they would be self-convicted of the +absurdity of maintaining a great generalization on a confessedly +untenable basis. For example, a few years ago I was allowed to raise a +debate in the Biological Section of the British Association on the +question to which the present chapters are devoted. But the debate ended +as I had anticipated that it must end. No one of the naturalists present +could give even the vaguest definition of what was meant by a +species--or, consequently, of a character as specific. On this account +the debate ended in as complete a destruction as was possible of the +doctrine that all the distinctive characters of every species must +necessarily be useful, vestigial, or correlated. For it became +unquestionable that the same generalization admitted of being made, with +the same degree of effect, touching all the distinctive characters of +every "snark." + + [122] It is almost needless to say that by a definition as "logical" + is meant one which, while including all the differentiae of + the thing defined, excludes any qualities which that thing may + share in common with any other thing. But by definitions as + "logically possible" I mean the number of separate definitions + which admit of being correctly given of the same thing from + different points of view. Thus, for instance, in the present + case, since the above has been in type the late M. + Quatrefages' posthumous work on _Darwin et ses Précurseurs + Français_ has been published, and gives a long list of + definitions of the term "species" which from time to time have + been enunciated by as many naturalists of the highest standing + as such (pp. 186-187). But while none of these twenty or more + definitions is logical in the sense just defined, they all + present one or other of the differentiae given by those in the + text. + +Probably, however, it will be thought unfair to have thus sprung a +difficult question of definition in oral debate. Therefore I allude to +this fiasco at the British Association, merely for the purpose of +emphasizing the necessity of agreeing upon some definition of a species, +before we can conclude anything with regard to the generalization of +specific characters as necessarily due to natural selection. But when a +naturalist has had full time to consider this fundamental matter of +definition, and to decide on what his own shall be, he cannot complain +of unfairness on the part of any one else who holds him to what he thus +says he means by a species. Now Mr. Wallace, in his last work, has given +a matured statement of what it is that he means by a species. This, +therefore, I will take as the avowed basis of his doctrine touching the +necessary origin and maintenance of all specific characters by natural +selection. His definition is as follows:-- + + "An assemblage of individuals which have become somewhat modified + in structure, form, and constitution, _so as to adapt them to + slightly different conditions of life_; which can be differentiated + from allied assemblages; which reproduce their like; which usually + breed together; and, perhaps, when crossed with their near allies, + always produce offspring which are more or less sterile _inter + se_[123]." + + [123] Darwinism, p. 167. + +From this definition the portion which I have italicized must be omitted +in the present discussion, for the reasons already given while +considering definition No. 5. What remains is a combination of Nos. 2 +and 4. According to Mr. Wallace, therefore, our criterion of a species +is to be the heredity of peculiar characters, combined, perhaps, with a +more or less exclusive fertility of the component individuals _inter +se_. This is the basis on which his generalization of the utility of +specific characters as necessary and universal is reared. Here, then, we +have something definite to go upon, at all events as far as Mr. Wallace +is concerned. Let us see how far such a basis of definition is competent +to sustain his generalization. + +First of all it must be remarked that, as species have actually been +constituted by systematists, the test of exclusive fertility does not +apply. For my own part I think this is to be regretted, because I +believe that such is the only natural--and therefore the only +firm--basis on which specific distinctions can be reared. But, as +previously observed, this is not the view which has been taken by our +species-makers. At most they regard the physiological criterion as but +lending some additional weight to their judgement upon morphological +features, in cases where it is doubtful whether the latter alone are of +sufficient distinctness to justify a recognition of specific value. Or, +conversely, if the morphological features are clearly sufficient to +justify such a recognition, yet if it happens to be known that there is +full fertility between the form presenting them and other forms which do +not, then the latter fact will usually prevent naturalists from +constituting the well differentiated form a species on grounds of its +morphological features alone--as, for instance, in the case of our +domesticated varieties. In short, the physiological criterion has not +been employed with sufficient closeness to admit of its being now +comprised within any practical definition of the term "species"--if by +this term we are to understand, not what any one may think species +_ought to be_, but what species actually _are_, as they have been +constituted for us by their makers. + +From all this it follows that the definition of the term "species" on +which Mr. Wallace relies for his deduction with respect to specific +characters, is the definition No. 4. In other words, omitting his +_petitio principii_ and his allusion to the test of fertility, the great +criterion in his view is the criterion of Heredity. And in this all +other evolutionists, of whatever school, will doubtless agree with him. +They will recognize that it is really the distinguishing test between +"climatic varieties" and "true species," so that however widely or +however constantly the former may diverge from one another in regard to +their peculiar characters, they are not to be classed among the latter +unless their peculiar characters are likewise hereditary characters. + +Now, if we are all agreed so far, the only question that remains is +whether or not this criterion of Heredity is capable of supplying a +basis for the generalization, that all characters which have been ranked +as of specific value must necessarily be regarded as presenting also an +adaptive, or life-serving, value? I will now endeavour to show that +there are certain very good reasons for answering this question in the +negative. + + +(A.) + +In the first place, even if the modifications induced by the direct +action of a changed environment are not hereditary, who is to know that +they are not? Assuredly not the botanist or zoologist who in a +particular area finds what he is fully entitled to regard as a +well-marked specific type. Only by experiments in transposition could it +be proved that the modifications have been produced by local conditions; +and although the researches of many experimentalists have shown how +considerable and how constant such modifications may be, where is the +systematic botanist who would ever think of transplanting an apparently +new species from one distant area to another before he concludes that it +is a new species? Or where is the systematic zoologist who would take +the trouble to transport what appears to be an obviously endemic species +of animal from one country to another before venturing to give it a new +specific name? No doubt, both in the case of plants and animals, it is +tacitly assumed that constant differences, if sufficient in amount to be +regarded as specific differences are hereditary; but there is not one +case in a hundred where the validity of this assumption has ever been +tested by experiments in transposition. Therefore naturalists are apt to +regard it as remarkable when the few experiments which have been made in +this direction are found to negative their assumption--for example, +that a diagnostic character in species of the genus _Hieratium_ is found +by transplantation not to be hereditary, or that the several named +species of British trout are similarly proved to be all "local +varieties" of one another. But, in point of fact, there ought to be +nothing to surprise us in such results--unless, indeed, it is the +unwarrantable nature of the assumption that any given differences of +size, form, colour, &c., which naturalists may have regarded as of +specific value, are, on this account, hereditary. Indeed, so surprising +is this assumption in the face of what we know touching both the extent +and the constancy of climatic variation, that it seems to me such a +naturalist as Kerner, who never considers the criterion of heredity at +all, is less assailable than those who profess to constitute this their +chief criterion of specific distinction. For it is certain that whatever +their professions may have nowadays become, systematic naturalists have +never been in the habit of really following this criterion. In theory +they have of late years attached more and more weight to definition No. +4; but in practice they have always adopted definition No. 3. The +consequence is, that in literally numberless cases (particularly in the +vegetable kingdom) "specific characters" are assumed to be hereditary +characters merely because systematic naturalists have bestowed a +specific name on the form which presents them. Nor is this all. For, +conversely, even when it is known that constant morphological characters +are unquestionably hereditary characters, if they happen to present but +small degrees of divergence from those of allied forms, then the form +which presents them is not ranked as a species, but as a constant +variety. In other words, when definitions 3 and 4 are found to clash, it +is not 4, but 3, that is followed. In short, even up to the present +time, systematic naturalists play fast and loose with the criterion of +Heredity to such an extent, that, as above observed, it has been +rendered wellnigh worthless in fact, whatever may be thought of it in +theory. + +Now, unless all this can be denied, what is the use of representing that +a species is distinguished from a variety--"climatic" or otherwise--by +the fact that its constituent individuals "reproduce their like"? We are +not here engaged on any abstract question of what might have been the +best principles of specific distinction for naturalists to have adopted. +We are engaged on the practical question of the principles which they +actually have adopted. And of these principles the reproduction of like +by like, under all circumstances of environment, has been virtually +ignored. + + +(B.) + +In the second place, supposing that the criterion of Heredity had been +as universally and as rigidly employed by our systematists in their work +of constructing species as it has been but occasionally and loosely +employed, could it be said that even then a basis would have been +furnished for the doctrine that all specific characters must necessarily +be useful characters? Obviously not, and for the following reasons. + +It is admitted that climatic characters are not necessarily--or even +generally--useful characters. Consequently, if there be any reason for +believing that climatic characters may become in time hereditary +characters, the doctrine in question would collapse, even supposing that +all specific types were to be re-constituted on a basis of experimental +inquiry, for the purpose of ascertaining which of them conform to the +test of Heredity. Now there are very good reasons for believing that +climatic characters not unfrequently do become hereditary characters; +and it was mainly in view of those reasons that I deemed it worth while +to devote so much space in the preceding chapter to the facts of +climatic variation. I will now state the reasons in question under two +different lines of argument. + +We are not as yet entitled to conclude definitely against the possible +inheritance of acquired characters. Consequently, we are not as yet +entitled to assume that climatic characters--i. e. characters acquired +by converse with a new environment, continued, say, since the last +glacial period--can never have become congenital characters. But, if +they ever have become congenital characters, they will have become, at +all events as a general rule, congenital characters that are useless; +for it is conceded that, _quâ_ climatic characters, they have not been +due to natural selection. + +Doubtless the followers of Weismann will repudiate this line of +argument, if not as entirely worthless, at all events as too +questionable to be of much practical worth. But even to the followers of +Weismann it may be pointed out, that the Wallacean doctrine of the +origin of all specific characters by means of natural selection was +propounded many years before either Galton or Weismann had questioned +the transmission of acquired characters. However. I allow that this line +of argument has now become--for the time being at all events--a dubious +line, and will therefore at once pass on to the second line, which is +not open to doubt from any quarter. + +Whether or not we accept Weismann's views, it will here be convenient to +employ his terminology, since this will serve to convey the somewhat +important distinctions which it is now my object to express. + +In the foregoing paragraphs, under heading (A), we have seen that there +must be "literally numberless forms" which have been ranked as true +species, whose diagnostic characters are nevertheless not congenital. In +the case of plants especially, we know that there must be large numbers +of named species which do not conform to the criterion of Heredity, +although we do not know which species they are. For present purposes, +however, it is enough for us to know that there are many such named +species, where some change of environment has acted directly and +similarly on all the individual "somas" exposed to it, without affecting +their "germ-plasms," or the material bases of their hereditary +qualities. For named species of this kind we may employ the term +_somatogenetic species_. + +But now, if there are any cases where a change of environment does act +on the germ-plasms exposed to it, the result would be what we may call +_blastogenetic species_--i.e. species which conform to the criterion of +Heredity, and would therefore be ranked by all naturalists as "true +species." It would not signify in such a case whether the changed +conditions of life first affected the soma, and then, through changed +nutrition, the germ-plasm; or whether from the first it directly +affected the germ-plasm itself. For in either case the result would be a +"species," which would continue to reproduce its peculiar features by +heredity. + +Now, the supposition that changed conditions of life may thus affect the +congenital endowments of germ-plasm is not a gratuitous one. The sundry +facts already given in previous chapters are enough to show that the +origin of a blastogenetic species by the direct action on germ-plasm of +changed conditions of life is, at all events, a possibility. And a +little further thought is enough to show that this possibility becomes a +probability--if not a virtual certainty. Even Weismann--notwithstanding +his desire to maintain, as far as he possibly can, the "stability" of +germ-plasm--is obliged to allow that external conditions acting on the +organism may in some cases modify the hereditary qualities of its +germ-plasm, and so, as he says, "determine the phyletic development of +its descendants." Again, we have seen that he is compelled to interpret +the results of his own experiments on the climatic varieties of certain +butterflies by saying, "I cannot explain the facts otherwise than by +supposing the passive acquisition of characters produced by direct +influences of climate"; by which he means that in this case the +influence of climate acts directly on the hereditary qualities of +germ-plasm. Lastly, and more generally, he says:-- + + "But although I hold it improbable that individual variability can + depend on a direct action of external influences upon the + germ-cells and their contained germ-plasm, because--as follows from + sundry facts--the molecular structure of the germ-plasm must be + very difficult to change, yet it is by no means to be implied that + this structure may not possibly be altered by influences of the + same kind continuing for a very long time. Thus it seems to me the + possibility is not to be rejected, that influences continued for a + long time, that is, for generations, such as temperature, kind of + nourishment, &c., which may affect the germ-cells as well as any + other part of the organism, may produce a change in the + constitution of the germ-plasm. But such influences would not then + produce individual variation, but would necessarily modify in the + same way all the individuals of a species living in a certain + district. It is possible, though it cannot be proved, that many + climatic varieties have arisen in this manner." + +So far, then, we have testimony to this point, as it were, from a +reluctant witness. But if we have no theory involving the "stability of +germ-plasm" to maintain, we can scarcely fail to see how susceptible the +germ-plasm is likely to prove to changed conditions of life. For we know +how eminently susceptible it is in this respect when gauged by the +practical test of fertility; and as this is but an expression of its +extraordinarily complex character, it would indeed be surprising if it +were to enjoy any immunity against modification by changed conditions of +life. We have seen in the foregoing chapter how frequently and how +considerably somatogenetic changes are thus caused, so as to produce +"somatogenetic species"--or, where we happen to know that the changes +are not hereditary, "climatic varieties." But the constitution of +germ-plasm is much more complex than that of any of the structures which +are developed therefrom. Consequently, the only wonder is that hitherto +experimentalists have not been more successful in producing +"blastogenetic species" by artificial changes of environment. Or, as Ray +Lankester has well stated this consideration, "It is not difficult to +suggest possible ways in which the changed conditions, shown to be +important by Darwin, could act through the parental body upon the +nuclear matter of the egg-cell and sperm-cell, with its immensely +complex and therefore unstable constitution.... The wonder is, not that +[blastogenetic] variation occurs, but that it is not excessive and +monstrous in every product of fertilization[124]." + + [124] _Nature_, Dec. 12, 1889, p. 129. + +If to this it should be objected that, as a matter of fact, +experimentalists have not been nearly so successful in producing +congenital modifications of type by changed conditions of life as they +have been in thus producing merely somatic modifications; or if it +should be further objected that we have no evidence at all in nature of +a "blastogenetic species" having been formed by means of climatic +influences alone,--if these objections were to be raised, they would +admit of the following answer. + +With regard to experiments, so few have thus far been made upon the +subject, that objections founded on their negative results do not carry +much weight--especially when we remember that these results have not +been uniformly negative, but sometimes positive, as shown in Chapter VI. +With regard to plants and animals in a state of nature, the objection is +wholly futile, for the simple reason that in as many cases as changed +conditions of life may have caused an hereditary change of specific +type, there is now no means of obtaining "evidence" upon the subject. +But we are not on this account entitled to conclude against the +probability of such changes of specific type having been more or less +frequently thus produced. And still less can we be on this account +entitled to conclude against the _possibility_ of such a change having +ever occurred in any single instance. Yet this is what must be concluded +by any one who maintains that the origin of all species--and, _a +fortiori_, of all specific characters--must _necessarily_ have been due +to natural selection. + +Now, if all this be admitted--and I do not see how it can be reasonably +questioned--consider how important its bearing becomes on the issue +before us. If germ-plasm (using this term for whatever it is that +constitutes the material basis of heredity) is ever capable of having +its congenital endowments altered by the direct action of external +conditions, the resulting change of hereditary characters, whatever else +it may be, need not be an adaptive change. Indeed, according to +Weismann's theory of germ-plasm, the chances must be infinitely against +the change being an adaptive one. On the theory of pangenesis--that is +to say, on the so-called Lamarckian principles--there would be much more +reason for entertaining the possibly adaptive character of hereditary +change due to the direct action of the environment. Therefore we arrive +at this curious result. The more that we are disposed to accept +Weismann's theory of heredity, and with it the corollary that natural +selection is the sole cause of adaptive modification in species the less +are we entitled to assume that all specific characters must necessarily +be adaptive. Seeing that in nature there are presumably many cases like +those of Hoffmann's plants, Weismann's butterflies, &c., where the +hereditary qualities of germ-plasm have (on his hypothesis) been +modified by changed conditions of life, we are bound to believe that, in +all cases where such changes do not happen to be actively deleterious, +they will persist. And inasmuch as characters which are only of +"specific" value must be the characters most easily--and therefore most +frequently--induced by any slight changes in the constitution of +germ-plasm, while, for the same reason (namely, that of their trivial +nature) they are least likely to prove injurious, it follows that the +less we believe in the functionally-produced adaptations of Lamarck, the +more ought we to resist the assumption that all specific characters must +necessarily be adaptive characters. + + * * * * * + +Upon the whole, then, and with regard to the direct action of external +conditions, I conclude--not only from general considerations, but also +from special facts or instances quite sufficient for the purpose--that +these must certainly give rise to immense numbers of somatogenetic +species on the one hand, and probably to considerable numbers of +blastogenetic species on the other; that in neither case is there any +reason for supposing the distinctively "specific characters" to be other +than "neutral" or "indifferent"; while there are the best of reasons for +concluding the contrary. So that, under this division of our subject +alone (B), there appears to be ample justification for the statement +that "a large proportional number of specific characters" are in +reality, as they are in appearance, destitute of significance from a +utilitarian point of view. + + +(C.) + +Thus far in the present chapter we have been dealing exclusively with +the case of "climatic variation," or change of specific type due to +changes in the external conditions of life. But it will be remembered +that, in the preceding chapter, allusion was likewise made to changes of +specific type due to internal causes, or to what Darwin has called "the +nature of the organism." Under this division of our subject I mentioned +especially Sexual Selection, which is supposed to arise in the aesthetic +taste of animals themselves; Isolation, which is supposed to originate +new types by allowing the average characters of an isolated section of +an old type to develop a new history of varietal change, as we shall see +more fully in the ensuing part of this treatise; and the Laws of Growth, +which is a general term for the operation of unknown causes of change +incidental to the living processes of organisms which present the +change. + +Now, under none of these divisions of our subject can there be any +question touching the criterion of Heredity. For if new species--or even +single specific characters of new species--are ever produced by any of +these causes, they must certainly all "reproduce their like." Therefore +the only question which can here obtain is as to whether or not such +causes ever do originate new species, or even so much as new specific +characters. Mr. Wallace, though not always consistently, answers this +question in the negative; but the great majority of naturalists follow +Darwin by answering it in the affirmative. And this is enough to show +the only point which we need at present concern ourselves with +showing--viz. that the question is, at the least, an open one. For as +long as this question is an open one among believers in the theory of +natural selection, it must clearly be an unwarrantable deduction from +that theory, that all species, and _a fortiori_ all specific characters, +are necessarily due to natural selection. The deduction cannot be +legitimately drawn until the possibility of any other cause of specific +modification has been excluded. But the bare fact of the question as +just stated being still and at the least an open question, is enough to +prove that this possibility has not been excluded. Therefore the +deduction must be, again on this ground alone (C), unwarrantable. + + * * * * * + +Such are my several reasons--and it is to be observed that they are all +_independent_ reasons--for concluding that it makes no practical +difference to the present discussion whether or not we entertain +Heredity as a criterion of specific distinction. Seeing that our +species-makers have paid so little regard to this criterion, it is +neither absurd nor preposterous to have adduced, in the preceding +chapter, the facts of climatic variation. On the contrary, as the +definition of "species" which has been practically followed by our +species-makers in No. 3, and not No. 4, these facts form part and parcel +of our subject. It is perfectly certain that, in the vegetable kingdom +at all events, "a large proportional number" of specifically diagnostic +characters would be proved by experiment to be "somatogenetic"; while +there are numerous constant characters classed as varietal, although it +is well known that they are "blastogenetic." Moreover, we can scarcely +doubt that many specific characters which are also hereditary characters +owe their existence, not to natural selection, but to the direct action +of external causes on the hereditary structure of "germ-plasm"; while, +even apart from this consideration, there are at least three distinct +and highly general principles of specific change, which are accepted by +the great majority of Darwinists, and the only common peculiarity of +which is that they produce hereditary changes of specific types without +any reference to the principle of utility. + + + + +CHAPTER X. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_concluded_). + + +Our subject is not yet exhausted. For it remains to observe the +consequences which arise from the dogma of utility as the only _raison +d'être_ of species, or of specific characters, when this dogma is +applied in practice by its own promoters. + + * * * * * + +Any definition of "species"--excepting Nos. 1, 2, and 5, which may here +be disregarded--must needs contain some such phrase as the one with +which Nos. 3 and 4 conclude. This is, that peculiar characters, in order +to be recognized as of specific value, must present neither more nor +less than "some certain degree of distinctness." If they present more +than this degree of distinctness, the form, or forms, in question must +be ranked as generic; while if they present less than this degree of +distinctness, they must be regarded as varietal--and this even if they +are known to be mutually sterile. What, then, is this certain degree of +distinctness? What are its upper and lower limits? This question is one +that cannot be answered. From the very nature of the case it is +impossible to find a uniform standard of distinction whereby to draw +our boundary lines between varieties and species on the one hand, or +between species and genera on the other. One or two quotations will be +sufficient to satisfy the general reader upon this point. + +Mr. Wallace himself alludes to "the great difficulty that is felt by +botanists in determining the limits of species in many large genera," +and gives as examples well-known instances where systematic botanists of +the highest eminence differ hopelessly in their respective estimates of +"specific characters." Thus:-- + + "Mr. Baker includes under a single species, Rosa canina, no less + than twenty-eight named varieties distinguished by more or less + constant characters, and often confined to special localities, and + to these are referred about seventy of the species of British and + continental botanists. Of the genus Rubus or bramble, five British + species are given in Bentham's _Handbook of British Flora_, while + in the fifth edition of Babington's _Manual of British Botany_, + published about the same time, no less than forty-five species are + described. Of willows (Salix) the same two works enumerate fifteen + and thirty-one species respectively. The hawkweeds (Hieracium) are + equally puzzling, for while Mr. Bentham admits only seven British + species, Professor Babington describes no less than seventy-two, + besides several named varieties[125]." + + [125] _Darwinism_, p. 77. + +Mr. Wallace goes on to quote further instances, such as that of Draba +verna, which Jordan has found to present, in the south of France alone, +no less than fifty-two permanent varieties, which all "come true from +seed, and thus present all the characteristics of a true species"; so +that, "as the plant is very common almost all over Europe, and ranges +from North America to the Himalayas, the number of similar forms over +this wide area would probably have to be reckoned by hundreds, if not by +thousands[126]." + + [126] _Darwinism_, p. 77. + +One or two further quotations may be given to the same general effect, +selected from the writings of specialists in their several departments. + + "There is nothing that divides systematists more than what + constitutes a genus. Species that resemble each other more than + other species, is perhaps the best definition that can be given. + This is obviously an uncertain test, much depending on individual + judgement and experience; but that, in the evolution of forms, such + difficulties should arise in the limitation of genera and species + was inevitable. What is a generic character in one may be only a + specific character in another. As an illustration of the uncertain + importance of characters, I may mention the weevil genus + _Centrinus_ in which the leading characters in the classification + of the family to which it belongs are so mixed that systematists + have been content to keep the species together in a group that + cannot be defined.... No advantage or disadvantage is attached, + apparently, to any of the characters. There are about 200 species, + all American. + + The venation of the wings of insects is another example of + modifications without serving any special purpose. There is no vein + in certain Thripidae, and only a rudiment or a single vein in + Chalcididae. There are thousands of variations more or less marked, + some of the same type with comparatively trivial variation, others + presenting distinct types, even in the same family, such genera, + for example, as _Polyneura_, _Tettigetra_, _Huechys_, &c. in the + Cicadidae. + + Individual differences have often been regarded as distinctive of + species; varieties also are very deceptive, and races come very + near to species. A South-American beetle, _Arescus histrio_, has + varieties of yellow, red, and black, or these colours variously + intermixed, and, what is very unusual, longitudinal stripes in some + and transverse bars in others, and all taken in the same locality. + Mr. A. G. Butler, of the British Museum, is of opinion that 'what + is generally understood by the term species (that is to say, a + well-defined, distinct, and constant type, having no near allies) + is non-existent in the Lepidoptera, and that the nearest approach + to it in this order is a constant, though but slightly differing, + rare or local form--that genera, in fact, consist wholly of a + gradational series of such forms (Ann. Mag. Nat. Hist. 5, xix. + 103)[127].'" + + [127] Pascoe, _The Darwinian Theory of the Origin of Species_, 1891, + pp. 31-33, and 46. + +So much as regards entomology, and still living forms. In illustration +of the same principles in connexion with palaeontological series, I may +quote Würtenberger, who says:-- + + "With respect to these fossil forms [i.e. multitudinous forms of + fossil Ammonites], it is quite immaterial whether a very short or a + somewhat longer part of any branch be dignified with a separate + name, and regarded as a species. The prickly Ammonites, classed + under the designation of Armata, are so intimately connected that + it becomes impossible to separate the accepted species sharply from + one another. The same remark applies to the group of which the + manifold forms are distinguished by their ribbed shells, and are + called Planulata[128]." + + [128] _Neuer Beitrag zum geologischen Beweis der Darwinischen + Theorie_, 1873. + +I had here supplied a number of similar quotations from writers in +various other departments of systematic work, but afterwards struck them +out as superfluous. For it is not to be anticipated that any competent +naturalist will nowadays dispute that the terms "variety," "species," +and "genus" stand for merely conventional divisions, and that whether a +given form shall be ranked under one or the other of them is often no +more than a matter of individual taste. From the nature of the case +there can be no objective, and therefore no common, standards of +delimitation. This is true even as regards any one given department of +systematic work; but when we compare the standards of delimitation which +prevail in one department with those which prevail in another, it +becomes evident that there is not so much as any attempt at agreeing +upon a common measure of specific distinction. + +But what, it may well be asked, is the use of thus insisting upon +well-known facts, which nobody will dispute? Well, in the first place, +we have already seen, in the last chapter, that it is incumbent on those +who maintain that all species, or even all specific characters, must be +due to natural selection, to tell us what they mean by a species, or by +characters as specific. If I am told to believe that the definite +quality A is a necessary attribute of B, and yet that B is "not a +distinct entity," but an undefinable abstraction, I can only marvel that +any one should expect me to be so simple. But, without recurring to this +point, the use of insisting on the facts above stated is, in the second +place, that otherwise I cannot suppose any general reader could believe +them in view of what is to follow. For he cannot but feel that the cost +of believing them is to render inexplicable the mental processes of +those naturalists who, in the face of such facts, have deduced the +following conclusions. + +The school of naturalists against which I am contending maintains, as a +generalization deduced from the theory of natural selection, that all +species, or even all specific characters, must necessarily owe their +origin to the principle of utility. Yet this same school does not +maintain any such generalization, either with regard to varietal +characters on the one hand, or to generic characters on the other. On +the contrary, Professor Huxley, Mr. Wallace, and all other naturalists +who agree with them in refusing to entertain so much as the abstract +possibility of any cause other than natural selection having been +productive of species, fully accept the fact of other causes having been +largely concerned in the production of varieties, genera, families, and +all higher groups, or of the characters severally distinctive of each. +Indeed, Mr. Wallace does not question what appears to me the extravagant +estimate of Professor Cope, that the non-adaptive characters distinctive +of those higher groups are fully equal, in point of numbers, to the +adaptive. But, surely, if the theory of evolution by natural selection +is, as we all agree, a true theory of the origin of species, it must +likewise be a true theory of the origin of genera; and if it be supposed +essential to the integrity of the theory in its former aspect that all +specific characters should be held to be useful, I fail to see how, in +regard to its latter aspect, we are so readily to surrender the +necessary usefulness of all generic characters. And exactly the same +remark applies to the case of constant "varieties," where again the +doctrine of utility as universal is not maintained. Yet, according to +the general theory of evolution, constant varieties are what Darwin +termed "incipient species," while species are what may be termed +"incipient genera." Therefore, if the doctrine of utility as universal +be conceded to fail in the case of varieties on the one hand and of +genera on the other, where is the consistency in maintaining that it +must "necessarily" hold as regards the intermediate division, species? +Truly the shade of Darwin may exclaim, "Save me from my friends." And +truly against logic of this description a follower of Darwin must find +it difficult to argue. If one's opponents were believers in special +creation, and therefore stood upon some definite ground while +maintaining this difference between species and all other taxonomic +divisions, there would at least be some issue to argue about. But when +on the one hand it is conceded that species are merely arbitrary +divisions, which differ in no respect as to the process of their +evolution from either varieties or genera, while on the other hand it is +affirmed that there is thus so great a difference in the result, all we +can say is that our opponents are entangling themselves in the meshes of +a sheer contradiction. + +Or, otherwise stated, specific characters differ from varietal +characters in being, as a rule, more pronounced and more constant: on +this account advocates of utility as universal apply the doctrine to +species, while they do not feel the "necessity" of applying it to +varieties. But now, generic and all higher characters are even more +constant and more pronounced than specific characters--not to say, in +many cases, more generally diffused over a larger number of organisms +usually occupying larger areas. Therefore, _a fortiori_, if for the +reasons above stated evolutionists regard it as a necessary deduction +from the theory of natural selection that all specific characters must +be useful, much more ought it to be a necessary deduction from this +theory that all generic, and still more all higher, characters must be +useful. But, as we have seen, this is not maintained by our opponents. +On the contrary, they draw the sharpest distinction between specific and +all other characters in this respect, freely conceding that both those +below and those above them need not--and very often do not--present any +utilitarian significance. + +Although it appears to me that this doctrine is self-contradictory, and +on this ground alone might be summarily dismissed, as it is now held in +one or other of its forms by many naturalists, I will give it a more +detailed consideration in both its parts--namely, first with respect to +the distinction between varieties and species, and next with respect to +the distinction between species and genera. + + * * * * * + +Until it can be shown that species are something more than merely +arbitrary divisions, due to the disappearance of intermediate varietal +links; that in some way or another they _are_ "definite entities," which +admit of being delineated by the application of some uniform or general +principles of definition; that, in short, species have only then been +classified as such when it has been shown that the origin of each has +been due to the operation of causes which have not been concerned in the +production of varieties;--until these things are shown, it clearly +remains a gratuitous dogma to maintain that forms which have been called +species differ from forms which have been called varieties in the +important respect, that they (let alone each of all their distinctive +characters) must necessarily have been due to the principle of utility. +Yet, as we have seen, even Mr. Wallace allows that a species is "not a +distinct entity," but "an assemblage of individuals which have become +somewhat modified in structure, form, and constitution"; while estimates +of the kinds and degrees of modification which are to be taken as of +specific value are conceded to be undefinable, fluctuating, and in not a +few cases almost ludicrously divergent. + +Perhaps one cannot more forcibly present the rational value of this +position than by noting the following consequences of it. Mr. Gulick +writes me that while studying the land-shells of the Sandwich Islands, +and finding there a rich profusion of unique varieties, in cases where +the intermediate varieties were rare he could himself have created a +number of species by simply throwing these intermediate varieties into +his fire. Now it follows from the dogma which we are considering, that, +by so doing, not only would he have created new species, but at the same +time he would have proved them due to natural selection, and endowed the +diagnostic characters of each with a "necessarily" adaptive meaning, +which previously it was not necessary that they should present. Before +his destruction of these intermediate varieties, he need have felt +himself under no obligation to assume that any given character at either +end of the series was of utilitarian significance: but, after his +destruction of the intermediate forms, he could no longer entertain any +question upon the matter, under pain of being denounced as a Darwinian +heretic. + +Now the application is self-evident. It is a general fact, which admits +of no denial, that the more our knowledge of any flora or fauna +increases, the greater is the number of intermediate forms which are +brought to light, either as still existing or as having once existed. +Consequently, the more that such knowledge increases, the more does our +catalogue of "species" diminish. As Kerner says, "bad species" are +always multiplying at the expense of "good species"; or, as Oscar +Schmidt (following Häckel) similarly remarks, if we could know as much +about the latter as we do about the former, "all species, without any +exception, would become what species-makers understand by 'bad +species'[129]." Hence we see that, just as Mr. Gulick could have created +good species by secretly destroying his intermediate varieties, so has +Nature produced her "good species" for the delectation of systematists. +And just as Mr. Gulick, by first hiding and afterwards revealing his +intermediate forms, could have made the self-same characters in the +first instance necessarily useful, but ever afterwards presumably +useless, so has Nature caused the utility of diagnostic characters to +vary with our knowledge of her intermediate forms. It belongs to the +essence of our theory of descent, that in _all_ cases these intermediate +forms must either be now existing or have once existed; and, therefore, +that the work of species-makers consists in nothing more than marking +out the _lacunae_ in our knowledge of them. Yet we are bound to believe +that wherever these _lacunae_ in our knowledge occur, there occurs also +the objective necessity of causation as utilitarian--a necessity, +however, which vanishes so soon as our advancing information supplies +the intermediate forms in question. It may indeed appear strange that +the utility or non-utility of organic structures should thus depend on +the accidents of human knowledge; but this is the Darwinian faith, and +he who doubts the dogma is to be anathema. + + [129] _The Doctrine of Descent and Darwinism_, Eng. Trans. p. 102. + +Turning next to the similar distinction which it is sought to draw +between species and genera, here it will probably be urged, as I +understand it to be urged by Mr. Wallace, that generic characters (and +still more characters of families, orders, &c.) refer back to so remote +a state of things that utility may have been present at their birth +which has disappeared in their maturity. In other words, it is held that +all generic characters were originally specific characters; that as such +they were all originally of use; but that, after having been rendered +stable by heredity, many of them may have ceased to be of service to the +descendants of those species in which they originated, and whose +extinction has now made it impossible to divine what that service may +have been. + +Now, in the first place; this is not the interpretation adopted by +Darwin. For instance, he expressly contrasts such cases with those of +vestigial or "rudimentary" structures, pointing out that they differ +from vestigial structures in respect of their permanence. One quotation +will be sufficient to establish the present point. + + "A structure which has been developed through long-continued + selection, when it ceases to be of service to a species, generally + becomes variable, as we see with rudimentary organs, for it will no + longer be regulated by this same power of selection. But when, from + the nature of the organism and of the conditions, modifications + have been induced which are unimportant for the welfare of the + species, they may be, and apparently often have been, transmitted + in nearly the same state to numerous, otherwise modified, + descendants[130]." + + [130] _Origin of Species_, p. 175. + +Here, and in the context, we have a sufficiently clear statement of +Darwin's view--first, that unadaptive characters may arise in _species_ +as "fluctuating variations, which sooner or later become _constant_ +through the nature of the organism and of surrounding conditions, as +well as through the intercrossing of distinct individuals, but _not_ +through natural selection"[131]; second, that such unadaptive characters +may then be transmitted in this their stable condition to +species-progeny, so as to become distinctive of genera, families, &c.; +third, that, on account of such characters not being afterwards liable +to diverse adaptive modifications in different branches of the +species-progeny, they are of more value as indicating lines of pedigree +than are characters which from the first have been useful; and, lastly, +they are therefore now empirically recognized by systematists as of most +value in guiding the work of classification. To me it appears that this +view is not only perfectly rational in itself, but likewise fully +compatible with the theory of natural selection--which, as I have +previously shown, is _primarily_ a theory of adaptive characters, and +therefore not necessarily a theory of _all_ specific characters. But to +those who think otherwise, it must appear--and does appear--that there +is something wrong about such a view of the case--that it was not +consistent in the author of the _Origin of Species_ thus to refer +non-adaptive generic characters to a parentage of non-adaptive specific +characters. Nevertheless, as a matter of fact, Darwin was perfectly +consistent in putting forth this view, because, unlike Wallace, he was +not under the sway of any antecedent dogma erroneously deduced from the +theory of natural selection. + + [131] _Ibid._ p. 176: italics mine. + +Next without reference to Darwin's authority, let us see for ourselves +where the inconsistency really lies. To allow that generic characters +may be useless, while denying that specific characters can ever be so +(unless correlated with others that are useful), involves an appeal to +the argument from ignorance touching the ancestral habits, +life-conditions, &c., of a parent species now extinct. Well, even upon +this assumption of utility as obsolete, there remains to be explained +the "stability" of useless characters now distinctive of genera, +families, orders, and the rest. We know that specific characters which +have owed their origin to utility and have afterwards ceased to present +utility, degenerate, become variable, inconstant, "rudimentary," and +finally disappear. Why, then, should these things not happen with regard +to useless generic distinctions? Still more, why should they not happen +with regard to family, ordinal, and class distinctions? On the lines +against which I am arguing it would appear impossible that any answer to +this question can be suggested. For what explanation can be given of the +contrast thus presented between the obsolescence of specific characters +where previous utility is demonstrable, and the permanence of higher +characters whose previous utility is assumed? As we have already seen, +Mr. Wallace himself employs this consideration of permanence and +constancy against the view that any cause other than natural selection +can have been concerned in the origin and maintenance of _specific_ +characters. But he does not seem to see that the consideration cuts two +ways--and much more forcibly against his views than in favour of them. +For while, as already shown in the chapter before last, it is +sufficiently easy to dispose of the consideration as Wallace uses it (by +simply pointing out with Darwin that any causes other than natural +selection which may have been concerned in the genesis of _specific_ +characters, must, if equally uniform in their operation, equally give +rise to permanence and constancy in their results); on the other hand, +it becomes impossible to explain the stability of useless _generic_ +characters, if, as Wallace's use of the argument requires, natural +selection is the only possible cause of stability. The argument is one +that cannot be played with fast and loose. Either utility is the sole +condition to the stability of _any_ diagnostic character (in which case +it is not open to Mr. Wallace to assume that all _generic_ or higher +characters which are now useless have owed their origin to a past +utility); or else utility is not the sole condition to stability (in +which case his use of the present argument in relation to _specific_ +characters collapses). We have seen, indeed, in the chapter before last, +that his use of the argument collapses anyhow, or quite irrespective of +his inconsistent attitude towards generic characters, with which we were +not then concerned. But the point now is that, as a mere matter of +logic, the argument from stability as Wallace applies it to the case of +specific characters, is incompatible with his argument that useless +generic characters may originally have been useful specific characters. +It can scarcely be questioned that the transmutation of a species into a +genus must, as a rule, have allowed time enough for a newly +acquired--i.e. peculiar specific-character--to show some signs of +undergoing degeneration, if, as supposed, the original cause of its +development and maintenance was withdrawn when the parent species began +to ramify into its species-progeny. Yet, as Darwin says, "it is +notorious that specific characters are more variable than generic[132]." +So that, upon the whole, I do not see how on grounds of general +reasoning it is logically possible to maintain Mr. Wallace's distinction +between specific and generic characters in respect of necessary utility. + + [132] _Origin of Species_, p. 122. + +But now, and lastly, we shall reach the same conclusion if, discarding +all consideration of general principles and formal reasoning, we fasten +attention upon certain particular cases, or concrete facts. Thus, to +select only two illustrations within the limits of genera, it is a +diagnostic feature of the genus _Equus_ that small warty callosities +occur on the legs. It is impossible to suggest any useful function that +is now discharged by these callosities in any of the existing species of +the genus. If it be assumed that they must have been of some use to the +species from which the genus originally sprang, the assumption, it seems +to me, can only be saved by further assuming that in existing species of +the genus these callosities are in a vestigial condition--i. e. that in +the original or parent species they performed some function which is +now obsolete. But against these assumptions there lies the following +fact. The callosities in question are not similarly distributed through +all existing species of the genus. The horse has them upon all his four +legs, while other species have them only upon two. Therefore, if all +specific characters are necessarily due to natural selection, it is +manifest that these callosities are _not_ now vestigial: on the +contrary, they _must_ still be--or, at best, have recently been--of so +much importance to all existing species of the genus, that not only is +it a matter of selection-value to all these species that they should +possess these callosities; but it is even a matter of selection-value to +a horse that he should possess four of them, while it is equally a +matter of selection-value to the ass that he should possess only two. +Here, it seems to me, we have once more the doctrine of the necessary +utility of specific characters reduced to an absurdity; while at the +same time we display the incoherency of the distinction between specific +characters and generic characters in respect of this doctrine. For the +distinction in such a case amounts to saying that a generic character, +if evenly distributed among all the species, need not be an adaptive +character; whereas, if any one of the species presents it in a slightly +different form, the character must be, on this account, necessarily +adaptive. In other words, the uniformity with which a generic character +occurs among the species of the genus is taken to remove that character +from the necessarily useful class, while the absence of such uniformity +is taken as proof that the character must be placed within the +necessarily useful class. Which is surely no less a _reductio ad +absurdum_ with regard to the generic character than the one just +presented with regard to its variants as specific characters. And, of +course, this twofold absurdity is presented in all cases where a generic +character is unequally distributed among the constituent species of a +genus. + +[Illustration: Fig. 4.--Lower Teeth of Orang (after Tomes).] + +But here is an illustration of another class of cases. Mr. Tomes has +shown that the molar teeth of the Orang present an extraordinary and +altogether superfluous amount of attachment in their sockets--the fangs +being not only exceedingly long, and therefore deeply buried in the +jaw-bone, but also curving round one another, so as still further to +strengthen the whole[133]. In the allied genera of anthropoid apes there +is no such abnormal amount of attachment. Now, the question is, of what +conceivable use can it _ever_ have been, either to the existing genus, +or to its parent species, that such an abnormal amount of attachment +should obtain? It certainly is not required to prevent dislocation of +the teeth, seeing that in all allied genera, and even in man himself, +the amount of attachment is already so great that teeth will break +before they can be drawn by anything short of a dentist's forceps. +Therefore I conclude that this peculiarity in the dentition of the genus +must have arisen in its parent species by way of what Darwin calls a +"fluctuating variation," without utilitarian significance. And I adduce +it in the present connexion because the peculiarity is one which is +equally unamenable to a utilitarian explanation, whether it happens to +occur as a generic or a specific character. + + [133] _A Manual of Dental Anatomy_, p. 455. + +Numberless similar cases might be quoted; but probably enough has now +been said to prove the inconsistency of the distinction which our +opponents draw between specific and all higher characters in respect of +utility. In point of fact, a very little thought is enough to show that +no such distinction admits of being drawn; and, therefore, that any one +who maintains the doctrine of utility as universal in the case of +specific characters, must in consistency hold to the same doctrine in +the case of generic and all higher characters. And the fact that our +opponents are unable to do this becomes a virtual confession on their +part of the futility of the generalization which they have +propounded[134]. + + [134] It may be observed that this distinction was not propounded by + Mr. Wallace--nor, so far as I am aware, by anybody else--until + he joined issue with me on the subject of specific characters. + Whether he has always held this important distinction between + specific and generic characters, I know not; but, as + originally enunciated, his doctrine of utility as universal + was subject to no such limitation: it was stated + unconditionally, as applying to all taxonomic divisions + indifferently. The words have already been quoted on page 180; + and, if the reader will turn to them, he may further observe + that, prior to our discussion, Mr. Wallace made no allowance + for the principle of correlation, which, as we have seen, + furnishes so convenient a loop-hole of escape in cases where + even the argument from our ignorance of possible utility + appears absurd. In his latest work, however, he is much less + sweeping in his statements. He limits his doctrine to the case + of "specific characters" alone, and even with regard to them + makes unlimited drafts upon the principle of correlation. + +On what then do Mr. Wallace and his followers rely for their great +distinction between specific and all other characters in respect of +utility? This is the final and fundamental question which I must leave +these naturalists themselves to answer; for my whole contention is, that +it is unanswerable. But although I am satisfied that they have nothing +on which to base their generalization, it seems worth while to conclude +by showing yet one further point. And this is, that these naturalists +themselves, as soon as they quit merely abstract assertions and come to +deal with actual facts, contradict their own generalization. It is worth +while to show this by means of a few quotations, that we may perceive +how impossible it is for them to sustain their generalization in the +domain of fact. + +As it is desirable to be brief, I will confine myself to quoting from +Mr. Wallace. + + "Colour may be looked upon as a necessary result of the highly + complex chemical constitution of animal tissues and fluids. The + blood, the bile, the bones, the fat, and other tissues have + characteristic, and often brilliant colours, which we cannot + suppose to have been determined for any special purpose as colours, + since they are usually concealed. The external organs and + integuments, would, by the same general laws, naturally give rise + to a greater variety of colour[135]." + + [135] _Darwinism_, p. 297. + +Surely comment is needless. Have the colour of external organs and +integuments nothing to do with the determining of specific distinctions +by systematists? Or, may we not rather ask, are there any other +"characters" which have had more to do with their delineation of animal +species? Therefore, if "the external organs and integuments naturally +give rise to a greater variety of colours," for non-utilitarian reasons, +than is the case with internal organs and tissues; while even the latter +present, for similarly non-utilitarian reasons, such variety and +intensity of colours as they do; must it not follow that, on the ground +of the "Laws of Growth" alone, Mr. Wallace has conceded the entire case +as regards "a large proportional number of specific characters" being +non-adaptive--"spontaneous" in their occurrence, and "meaningless" in +their persistence? + +Once more:-- + + "The enormously lengthened plumes of the bird of paradise and of + the peacock, can, however, have no such use [i.e. for purposes of + defence], but must be rather injurious than beneficial in the + birds' ordinary life. The fact that they have been developed to so + great an extent in a few species is an indication of such perfect + adaptation to the conditions of existence, such complete success in + the battle for life, that there is, in the adult male at all + events, a surplus of strength, vitality, and growth-power, which is + able to expend itself in this way without injury. That such is the + case is shown by the great abundance of most of the species which + possess these wonderful superfluities of plumage.... Why, in allied + species, the development of accessory plumes has taken different + forms, we are unable to say, except that it may be due to that + individual variability which has served as a starting-point for so + much of what seems to us strange in form, or fantastic in colour, + both in the animal and vegetable world[136]." + + [136] _Darwinism_, pp. 292-3. + +Here, again, one need only ask, How can such statements be reconciled +with the great dogma, "which is indeed a necessary deduction from the +theory of Natural Selection, namely, that none of the definite facts of +organic nature, no special organ, no characteristic form or marking can +exist, but which must now be, or once have been, _useful_"? Can it be +said that the plumes of a bird of paradise present "no characteristic +form," or the tail of a peacock "no characteristic marking"? Can it be +held that all the "fantastic colours," which Darwin attributes to sexual +selection, and all the "strange forms" in the vegetable world which +present no conceivable reference to adaptation, are to be ascribed to +"individual variability" without reference to utility, while at the same +time it is held, "as a necessary deduction from the theory of Natural +Selection," that _all_ specific characters must be "_useful_"? Or must +we not conclude that we have here a contradiction as direct as a +contradiction can well be[137]? + + [137] Since the above was written both Mr. Gulick and Professor + Lloyd Morgan have independently noticed the contradiction. + +Nor is it any more possible to reconcile these contradictory statements +by an indefinite extension of the term "correlation," than we found it +to be in the cases previously quoted. It might indeed be logically +possible, howsoever biologically absurd, to attribute the tail of a +peacock--with all its elaboration of structure and pattern of colour, +with all the drain that its large size and weight makes upon the vital +resources of the bird, with all the increased danger to which it exposes +the bird by rendering it more conspicuous, more easy of capture, &c.--to +correlation with some useful character peculiar to peacocks. But to say +that it is due to correlation with general "vitality," is merely to +discharge the doctrine of correlation of any assignable meaning. +Vitality, or "perfect adaptation to the conditions of existence," is +obviously a prime condition to the occurrence of a peacock's tail, as it +is to the occurrence of a peacock itself; but this is quite a different +thing from saying that the specific characters which are presented by a +peacock's tail, although useless in themselves, are correlated with some +other and useful specific characters of the same bird--as we saw in a +previous chapter with reference to secondary sexual characters in +general. Therefore, when Mr. Wallace comes to the obvious question why +it is that even in "allied species," which must be in equally "perfect +adaptation to the conditions of existence," there are no such "wonderful +superfluities of plumage," he falls back--as he previously fell back--on +whatever unknown _causes_ it may have been which produced the peacock's +tail, when the primary _condition_ to their operation has been furnished +by "complete success in the battle for life." + +I have quoted the above passages, not so much for the sake of exposing +fundamental inconsistencies on the part of an adversary, as for the sake +of observing that they constitute a much truer exposition of "Darwinism" +than do the contradictory views expressed in some other parts of the +work bearing that title. For even if characters of so much size and +elaboration as the tail of a peacock, the plumes of a bird of paradise +&c., are admitted to be due to non-utilitarian causes, much more must +innumerable other characters of incomparably less size and elaboration +be mere "superfluities." Without being actually deleterious, "a large +proportional number of specific characters," whose utility is not +apparent, must _a fortiori_ have been due to "individual variation," to +"general laws which determine the production" of such characters--or, in +short, to some causes other than natural selection. And this, I say, is +a doctrine much more in harmony with "Darwinism" than is the +contradictory doctrine which I am endeavouring to resist. + +But once again, and still more generally, after saying of "the delicate +tints of spring foliage, and the intense hues of autumn," that "as +colours they are unadaptive, and appear to have no more relation to the +well-being of plants themselves than do the colours of gems and +minerals," Mr. Wallace proceeds thus:-- + + "We may also include in the same category those algae and fungi + which have bright colours--the red snow of the Arctic regions, the + red, green, or purple seaweeds, the brilliant scarlet, yellow, + white or black agarics, and other fungi. All these colours are + probably the direct results of chemical composition or molecular + structure, and being thus normal products of the vegetable + organism, need no special explanation from our present point of + view; and the same remark will apply to the varied tints of the + bark of trunks, branches and twigs, which are often of various + shades of brown and green, or even vivid reds and yellows[138]." + + [138] _Darwinism_, p. 302. + +Here, as Mr. Gulick has already observed, "Mr. Wallace seems to admit +that instead of useless specific characters being unknown, they are so +common and so easily explained by 'the chemical constitution of the +organism' that they claim no special attention[139]." And whatever +answer Mr. Wallace may make to this criticism, I do not see how he is to +meet the point at present before us--namely, that, upon his own showing, +there are in nature numberless instances of "characters which are +useless without being hurtful," and which nevertheless present absolute +"constancy." If, in order to explain the contradiction, he should fall +back upon the principle of correlation, the case would not be in any way +improved. For, here again, if the term correlation were extended so as +to include "the chemical constitution or the molecular structure of the +organism," it would thereby be extended so as to discharge all Darwinian +significance from the term. + + [139] _American Journal of Science_, Vol. XL. art. I. on _The + Inconsistencies of Utilitarianism as the Exclusive Theory of + Organic Evolution_. + + +_Summary._ + +I will conclude this discussion of the Utility question by +recapitulating the main points in an order somewhat different from that +in which they have been presented in the foregoing chapters. Such a +variation may render their mutual connexions more apparent. But it is +only to the main points that allusion will here be made, and, in order +the better to show their independent character, I will separately number +them. + + * * * * * + +1. The doctrine of utility as universal, whether with respect to species +only or likewise with respect to specific characters, is confessedly an +_a priori_ doctrine, deduced by way of general reasoning from the theory +of natural selection. + +2. Being thus founded exclusively on grounds of deduction, the doctrine +cannot be combated by any appeal to facts. For this question is not one +of fact: it is a question of reasoning. The treatment of our subject +matter is logical: not biological. + +3. The doctrine is both universal and absolute. According to one form of +it _all_ species, and according to another form of it _all_ specific +characters, must _necessarily_ be due to the principle of utility. + +4. The doctrine in both its forms is deduced from a definition of the +theory of natural selection as a theory, and the sole theory, of the +origin of _species_; but, as Professor Huxley has already shown, it does +not really follow, even from this definition, that all specific +_characters_ must be "necessarily useful." Hence the two forms of the +doctrine, although coincident with regard to species, are at variance +with one another in respect of specific characters. Thus far, of course, +I agree with Professor Huxley; but if I have been successful in showing +that the above definition of the theory of natural selection is +logically fallacious, it follows that the doctrine in both its forms is +radically erroneous. The theory of natural selection is not, accurately +speaking, a theory of the origin of species: it is a theory of the +origin and cumulative development of adaptations, to whatever order of +taxonomic division these may happen to belong. Thus the premisses of the +deduction which we are considering collapse: the principle of utility is +shown not to have any other or further reference to species, or to +specific characters, than it has to fixed varieties, genera, families, +&c., or to the characters severally distinctive of each. + +5. But, quitting all such antecedent considerations, we next proceeded +to examine the doctrine _a posteriori_, taking the arguments which have +been advanced in favour of the doctrine, other than those which rest +upon the fallacious definition. These arguments, as presented by Mr. +Wallace, are two in number. + +First, it is represented that natural selection must occupy the whole +field, because no other principle of change can be allowed to operate in +the presence of natural selection. Now I fully agree that this statement +holds as regards any principle of change which is deleterious, but I +cannot agree that it does so as regards any such principle which is +merely neutral. No reason has ever been shown why natural selection +should interfere with "indifferent" characters--to adopt Professor +Huxley's term--supposing such to have been produced by any of the +agencies which we shall presently have to name. Therefore this +argument--or rather assertion--goes for nothing. + +Mr. Wallace's second argument is, that utility is the only principle +which can endow specific characters with their characteristic stability. +But this again is mere assertion. Moreover, it is assertion opposed +alike to common sense and to observable fact. It is opposed to common +sense, because it is obvious that any other principle would equally +confer stability on characters due to it, provided that its action is +constant, as Darwin expressly held. Again, this argument is opposed to +fact, because we know of thousands of cases where peculiar characters +are stable, which, nevertheless, cannot possibly be due to natural +selection. Of such are the Porto Santo rabbits, the niata cattle, the +ducks in St. James' Park, turkeys, dogs, horses, &c., and, in the case +of plants, wheat, cabbage, maize, &c., as well as all the hosts of +climatic varieties, both of animals and plants, in a state of nature. +Indeed, on taking a wide survey of the facts, we do not find that the +principle of utility is any better able to confer stability of character +than are many other principles, both known and unknown. Nay, it is +positively less able to do so than are some of these other principles. +Darwin gives two very probable reasons for this fact; but I need not +quote them a second time. It is enough to have seen that this argument +from stability or constancy is no less worthless than the previous one. +Yet these are the only two arguments of a corroborative kind which Mr. +Wallace adduces whereby to sustain his "necessary deduction." + +6. At this point, therefore, it may well seem that we need not have +troubled ourselves any further with a generalization which does not +appear to have anything to support it. And to this view of the case I +should myself agree, were it not that many naturalists now entertain the +doctrine as an essential article of their Darwinian creed. Hence, I +proceeded to adduce considerations _per contra_. + +Seeing that the doctrine in question can only rest on the assumption +that there is no cause other than natural selection which is capable of +originating any single species--if not even so much as any single +specific character--I began by examining this assumption. It was shown +first that, on merely antecedent grounds, the assumption is "infinitely +precarious." There is absolutely no justification for the statement that +in all the varied and complex processes of organic nature natural +selection is the only possible cause of specific change. But, apart +altogether from this _a priori_ refutation of the dogma, our analysis +went on to show that, in point of actual fact, there are not a few +well-known causes of high generality, which, while having no connexion +with the principle of utility, are demonstrably capable of originating +species and specific characters--if by "species" and "specific +characters" we are to understand organic types which are ranked as +species, and characters which are described as diagnostic of species. +Such causes I grouped under five different headings, viz. Climate, Food, +Sexual Selection, Isolation, and Laws of Growth. Sexual Selection and +Isolation are, indeed, repudiated by Mr. Wallace; but, in common I +believe with all biologists, he accepts the other three groups of causes +as fully adequate to produce such kinds and degrees of modification as +are taken to constitute specific distinction. And this is amply +sufficient for our present purposes. Besides, under the head of Sexual +Selection, it does not signify in the present connexion whether or not +we accept Darwin's theory on this subject. For, in any case, the facts +of secondary sexual characters are indisputable: these characters are, +for the most part, specific characters: and they cannot be explained by +the principle of utility. Even Mr. Wallace does not attempt to do so; +and the explanation which he does give is clearly incompatible with his +doctrine touching the necessarily life-serving value of all specific +characters. Lastly, the same has to be said of the Laws of Growth. For +we have just seen that on the grounds of this principle likewise Mr. +Wallace abandons the doctrine in question. As regards Isolation, much +more remains to be said in the ensuing portion of this work, while, as +regards Climatic Variation, there are literally innumerable cases where +changes of specific type are known to have been caused by this means. + +7. To the latter class of cases, however, it will be objected that these +changes of specific type, although no doubt sufficiently "stable" so +long as the changed conditions remain constant, are found by experiment +not to be hereditary; and this clearly makes all the difference between +a true specific change and a merely fictitious appearance of it. + +Well, in the first place, this objection can have reference only to the +first two of the five principles above stated. It can have no reference +to the last three, because of these heredity constitutes the very +foundation. This consideration ought to be borne in mind throughout. But +now, in the second place, even as regards changes produced by climate +and food, the reply is nugatory. And this for three reasons, as follows. + +(_a_) No one is thus far entitled to conclude against the possible +transmission of acquired characters; and, so long as there is even so +much as a possibility of climatic (or any other admittedly +non-utilitarian) variations becoming in this way hereditary, the reply +before us merely begs the question. + +(_b_) Even supposing, for the sake of argument, that acquired characters +can never in any case become congenital, there remains the strong +probability--sanctioned as such even by Weismann--that changed +conditions of life may not unfrequently act upon the material of +heredity itself, thus giving rise to specific changes which are from +the first congenital, though not utilitarian. Indeed, there are not a +few facts (Hoffmann's plants, Weismann's butterflies, &c.), which can +only be explained either in this way, or as above (_a_). And in the +present connexion it is immaterial which of these alternative +explanations we choose to adopt, seeing that they equally refute our +opponents' objection. And not only do these considerations--(_a_) and +(_b_)--refute this particular objection; they overturn on new and +independent grounds the whole of our opponents' generalization. For the +generalization is, that the principle of utility, acting through natural +selection, is "necessarily" the sole principle which can be concerned in +hereditary changes of specific type. But here we perceive both a +possibility (_a_) and a probability (_b_), if not indeed a certainty, +that quite other principles have been largely concerned in the +production of such changes. + +(_c_) Altogether apart from these considerations, there remains a much +more important one. For the objection that fixed--or "stable"--climatic +varieties differ from true species in not being subject to heredity, +raises the question--What are we to understand by a "species"? This +question, which was thus far purposely left in abeyance, had now to be +dealt with seriously. For it would clearly be irrational in our +opponents to make this highly important generalization with regard to +species and specific characters, unless they are prepared to tell us +what they mean by species, and therefore by characters as specific. In +as far as there is any ambiguity on this point it makes entirely for +our side in the debate, because even any small degree of uncertainty +with regard to it would render the generalization in question +proportionally unsound. Yet it is notorious that no word in existence is +more vague, or more impossible to define, than the word "species." The +very same men who at one time pronounce their great generalization with +regard to species, at another time asseverate that "a species is not a +definite entity," but a merely abstract term, serving to denote this +that and the other organic type, which this that and the other +systematist regards as deserving such a title. Moreover it is +acknowledged that systematists differ among themselves to a wide extent +as to the kinds and degrees of peculiarity which entitle a given form to +a specific rank. Even in the same department of systematic work much +depends on merely individual taste, while in different departments +widely different standards of delimination are in vogue. Hence, our +_reductio ad absurdum_ consists in this--that whether a given form is to +be regarded as necessarily due to natural selection, and whether all its +distinctive characters are to be regarded as necessarily utilitarian +characters, will often depend on whether it has been described by +naturalist A or by naturalist B. There is no one criterion--there is not +even any one set of criteria--agreed upon by naturalists for the +construction of specific types. In particular, as regards the principle +of heredity, it is not known of one named species in twenty--probably +not in a hundred--whether its diagnostic characters are hereditary +characters; while, on the other hand, even in cases where experiment has +proved "constant varieties" to be hereditary--and even also +cross-sterile with allied varieties--it is only some three or four +living botanists who for these reasons advocate the elevation of such +varieties to the rank of species. In short, as we are not engaged on any +abstract question touching the principles on which species ought to have +been constituted by their makers, but upon the actual manner in which +they have been, the criterion of heredity must needs be disregarded in +the present discussion, as it has been in the work of systematists. And +the result of this is, that any objection to our introducing the facts +of climatic variation in the present discussion is excluded. In +particular, so far as any question of heredity is concerned, all these +facts are as assuredly as they are cogently relevant. It is perfectly +certain that there is "a large proportional number" of named +species--particularly of plants--which further investigation would +resolve into climatic varieties. With the advance of knowledge, "bad +species" are always increasing at the expense of "good species," so that +we are now justified in concluding with Kerner, Häckel, and other +naturalists best qualified to speak on this subject, that if we could +know as much about the past history and present relations of the +remaining good species as we do about the bad, all the former, without +exception, would become resolved into the latter. In point of fact, and +apart altogether from the inductive experience on which this conclusion +is based, the conclusion follows "as a necessary deduction" from the +general theory of descent. For this theory essentially consists in +supposing either the past or the present existence of intermediate +varietal forms in all cases, with the consequence that "good species" +serve merely to mark _lacunae_ in our knowledge of what is everywhere a +finely graduated process of transmutation. Hence, if we place this +unquestionably "necessary deduction" from the general theory of descent +side by side with the alleged "necessary deduction" from the theory of +natural selection, we cannot avoid the following absurdity--Whether or +not a given form is to be regarded as necessarily due to natural +selection, and all its characters necessarily utilitarian, is to be +determined, and determined solely, by the mere accident of our having +found, or not having found, either in a living or in a fossil state, its +varietal ancestry. + +8. But this leads us to consider the final and crowning incongruities +which have been dealt with in the present chapter. For here we have +seen, not only that our opponents thus draw a hard and fast line between +"varieties" and "species" in regard to "necessary origin" and "necessary +utility," but that they further draw a similar line between "species" +and "genera" in the same respects. Yet, in accordance with the general +theory of evolution, it is plainly as impossible to draw any such line +in the one case as it is to do so in the other. Just as fixed varieties +are what Darwin called "incipient species," so are species incipient +genera, genera incipient families, and so on. Evolutionists must believe +that the process of evolution is everywhere the same. Nevertheless, +while admitting all this, the school of Huxley contradicts itself by +alleging some unintelligible exception in the case of "species," while +the school of Wallace presses this exception so as to embrace "specific +characters." Indeed Mr. Wallace, while maintaining that all specific +characters must necessarily be useful, maintains at the same time that +any number of varietal characters on the one hand, and a good half of +generic characters on the other, are probably useless. Thus he +contradicts his argument from the "constancy of specific characters" +(seeing that generic characters are still more constant), as later on we +saw that he contradicts his deductive generalization touching their +necessary utility, by giving a non-utilitarian explanation of whole +multitudes of specific characters. I need not, however, again go over +the ground so recently traversed; but will conclude by once more +recurring to the only explanation which I have been able to devise of +the otherwise inexplicable fact, that in regard to this subject so many +naturalists still continue to entangle themselves in the meshes of +absurdity and contradiction. + + * * * * * + +The only conceivable explanation is, that these naturalists have not yet +wholly divested themselves of the special creation theory. Although +professing to have discarded the belief that "species" are "definite +entities," differing in kind from "varieties" on the one hand and from +"genera" on the other, these writers are still imbued with a vague +survival of that belief. They well know it to belong to the very essence +of their new theory that "species" are but "pronounced varieties," or, +should we prefer it, "incipient genera"; but still they cannot +altogether escape the pre-Darwinian conception of species as organic +units, whose single mode of origin need not extend to other taxonomic +groups, and whose characters therefore present some exceptional +significance to the scientific naturalist. So to speak, such divinity +doth still hedge a species, that even in the very act of declaring it +but an idol of their own creation, these naturalists bow before their +fetish as something that is unique--differing alike in its origin and in +its characters from the varieties beneath and the genera above. The +consequence is that they have endeavoured to reconcile these +incompatible ideas by substituting the principle of natural selection +for that of super-natural creation, where the particular case of +"species" is concerned. In this way, it vaguely seems to them, they are +able to save the doctrine of some one mode of origin as appertaining to +species, which need not "necessarily" appertain to any other taxonomic +division. All other such divisions they regard, with their pre-Darwinian +forefathers, as merely artificial constructions; but, likewise with +these forefathers, they look upon species as natural divisions, proved +to be such by a single and necessary mode of origin. Hence, Mr. Wallace +expressly defines a species with reference to this single and necessary +mode of origin (_see_ above, p. 235), although he must be well aware +that there is no better, or more frequent, proof of it in the case of +species, than there is in that of somewhat less pronounced types on the +one hand (fixed varieties), or of more pronounced types on the other +(genera, families, &c.). Hence, also, the theory of natural selection is +defined as _par excellence_ a theory of the origin of species; it is +taken as applying to the particular case of the origin of species in a +peculiarly stringent manner, or in a manner which does not apply to the +origin of any other groups. And I believe that an important accessory +reason of the continuance of this view for more than thirty years after +the publication of the _Origin of Species by means of Natural +Selection_, is to be found in the title of that work. "Natural +Selection" has thus become verbally associated with "Origin of Species," +till it is thoughtlessly felt that, in some way or another, natural +selection must have a peculiar reference to those artificially +delineated forms which stand anywhere between a fixed variety and a +so-called genus. This verbal association has no doubt had the effect of +still further preserving the traditional halo of mystery which clings to +the idea of a "species." Hence it comes that the title which Darwin +chose--and, looking to the circumstances of the time, wisely chose--for +his great work, has subsequently had the effect of fostering the very +idea which it was the object of that work to dissipate, namely, that +species are peculiar entities, which differ more or less in origin or +kind from all other taxonomic groups. The full title of this work +is--_The Origin of Species by means of Natural Selection: or the +Preservation of Favoured Races in the Struggle for Life_. Now, supposing +that instead of this its author had chosen some such title as the +following:--_The Origin of Organic Types by means of Adaptive Evolution: +or Survival of the Fittest Forms in the Struggle for Life_. Of course +this would have been a bad substitute from various points of view; but +could any objection have been urged against it from our present point of +view? I do not see that there could. Yet, if such had been the title, I +have little doubt that we should never have heard of those great +generalizations with regard to species and specific characters, the +futility of which it has been the object of these chapters to expose. + + * * * * * + +In conclusion, it only remains to reiterate that in thus combating what +appears to me plainly erroneous deductions from the theory of natural +selection, I am in no wise combating that theory itself. On the +contrary, I hope that I am rendering it no unimportant service by +endeavouring to relieve it of a parasitic growth--an accretion of false +logic. Regarding as I do the theory of natural selection as, primarily, +a theory of the origin (or cumulative development) of adaptations, I see +in merely non-adaptive characters--be they "specific" or other--a +comparatively insignificant class of phenomena, which may be due to a +great variety of incidental causes, without any further reference to the +master-principle of natural selection than that in the presence of this +principle none of these non-adaptive characters can be actively +deleterious. But that there may be "any number of indifferent +characters" it is no part of the theory of natural selection to deny; +and all attempts to foist upon it _a priori_ "deductions" opposed alike +to the facts of nature and to the logic of the case, can only act to the +detriment of the great generalization which was expressly guarded from +such fallacies by the ever-careful judgement of Darwin. + + + + +APPENDICES AND NOTES + + + + +APPENDIX I. + +ON PANMIXIA. + + +There are several points of considerable theoretical importance +connected with Panmixia, which were omitted from the text, in order to +avoid distracting attention from the main issue which is there under +consideration. These side issues may now be appropriately presented in +the form in which they were published in _Nature_, March 13, 1890[140]. +After stating, in almost the same words, what has already been said in +Chapter X, this paper proceeds, with the exception of a few verbal +alterations, as follows. + + [140] Vol. xli. p. 438. + + "There is, however, one respect in which Professor Weismann's + statement of the principle of panmixia differs from that which was + considered by Mr. Darwin; and it is this difference of + statement--which amounts to an important difference of theory--that + I now wish to discuss. + + "The difference in question is, that while Professor Weismann + believes the cessation of selection to be capable of inducing + degeneration down to the almost complete disappearance of a + rudimentary organ, I have argued that, _unless assisted by some + other principle_, it can at most only reduce the degenerating organ + to considerably above one-half its original size--or probably not + through so much as one-quarter. The ground of this argument (which + is given in detail in the _Nature_ articles of 1873-1874) is, that + panmixia depends for its action upon fortuitous variations round an + ever-diminishing average--the average thus diminishing because it + is no longer _sustained_ by natural selection. But although no + longer sustained by _natural selection_, it does continue to be + sustained by _heredity_; and therefore, as long as the force of + heredity persists unimpaired, fortuitous variations alone--or + variation which is no longer controlled by natural + selection--cannot reduce the dwindling organ to so much as one-half + of its original size; indeed, as above foreshadowed, the balance + between the positive force of heredity and the negative effects of + promiscuous variability will most likely be arrived at above the + middle line thus indicated. Only if for any reason the force of + heredity begins to fail can the average round which the cessation + of selection works become a progressively diminishing average. In + other words, so long as the original force of heredity as regards + the useless organ remains unimpaired, the mere withdrawal of + selection cannot reduce the organ much below the level of + efficiency above which it was previously _maintained_ by the + _presence_ of selection. If we take this level to be 80 or 90 per + cent. of the original size, cessation of selection will reduce the + organ through the 10 or 20 per cent., and there leave it + fluctuating about this average, unless for any reason the force of + heredity begins to fail--in which case, of course, the average will + progressively fall in proportion to the progressive weakening of + this force. + + "Now, according to my views, the force of heredity under such + circumstances is always bound to fail, and this for two reasons. In + the first place, it must usually happen that when an organ becomes + useless, natural selection as regards that organ will not only + _cease_, but become _reversed_. For the organ is now absorbing + nutriment, causing weight, occupying space, and so on, _uselessly_. + Hence, even if it be not also a source of actual danger, 'economy + of growth' will determine a reversal of selection against an organ + which is now not merely useless, but deleterious. And this + degenerating influence of the reversal of selection will throughout + be assisted by the cessation of selection, which will now be always + acting round a continuously sinking average. Nevertheless, a point + of balance will eventually be reached in this case, just as it was + in the previous case where the cessation of selection was supposed + to be working alone. For, where the reversal of selection has + reduced the diminishing organ to so minute a size that its presence + is no longer a source of detriment to the organism, the cessation + of selection will carry the reduction a small degree further; and + then the organ will remain as a 'rudiment.' And so it will remain + permanently, unless there be some further reason why the still + remaining force of heredity should be abolished. This further (or + second) reason I found in the consideration that, however enduring + we may suppose the force of heredity to be, we cannot suppose that + it is actually everlasting; and, therefore, that we may reasonably + attribute the eventual disappearance of rudimentary organs to the + eventual failure of heredity itself. In support of this view there + is the fact that rudimentary organs, although very persistent, are + not everlasting. That they should be very persistent is what we + should expect, if the hold which heredity has upon them is great in + proportion to the time during which they were originally useful, + and thus firmly stamped upon the organization by natural selection + causing them to be strongly inherited in the first instance. For + example, we might expect that it would be more difficult finally to + eradicate the rudiment of a wing than the rudiment of a feather; + and accordingly we find it a general rule that long-enduring + rudiments are rudiments of organs distinctive of the higher + taxonomic divisions--i.e. of organs which were longest in building + up, and therefore longest sustained in a state of working + efficiency. + + "Thus, upon the whole, my view of the facts of degeneration remains + the same as it was when first published in these columns seventeen + years ago, and may be summarized as follows. + + "The cessation of selection when working alone (as it probably does + during the first centuries of its action upon structures or colours + which do not entail any danger to, or perceptible drain upon, the + nutritive resources of the organism) cannot cause degeneration + below, probably, some 10 to 20 per cent. But if from the first the + cessation of selection has been assisted by the _reversal_ of + selection (on account of the degenerating structure having + originally been of a size sufficient to entail a perceptible drain + on the nutritive resources of the organism, having now become a + source of danger, and so forth), the two principles acting together + will continue to reduce the ever-diminishing structure down to the + point at which its presence is no longer a perceptible disadvantage + to the species. When that point is reached, the reversal of + selection will terminate, and the cessation of selection will not + then be able of itself to reduce the organ through more than at + most a very few further percentages of its original size. But, + after this point has been reached, the now total absence of + selection, either for or against the organ, will sooner or later + entail this further and most important consequence, a failure of + heredity as regards the organ. So long as the organ was of use, its + efficiency was constantly _maintained_ by the _presence_ of + selection--which is merely another way of saying that selection was + constantly maintaining the force of heredity as regards that organ. + But as soon as the organ ceased to be of use, selection ceased to + maintain the force of heredity; and thus, sooner or later, that + force began to waver or fade. Now it is this wavering or fading of + the force of heredity, thus originally due to the cessation of + selection, that in turn co-operates with the still continued + cessation of selection in reducing the structure below the level + where its reduction was left by the actual reversal of selection. + So that from that level downwards the cessation of selection, and + the consequent failing of heredity, act and react in their common + work of causing obsolescence. In the case of newly added + characters, the force of heredity will be less than in that of more + anciently added characters; and thus we can understand the long + endurance of 'vestiges' characteristic of the higher taxonomic + divisions, as compared with those characteristic of the lower. But + in all cases, if time enough be allowed under the cessation of + selection, the force of heredity will eventually fall to zero, when + the hitherto obsolescent structure will finally become obsolete. In + cases of newly added and comparatively trivial characters, with + regard to which reversal of selection is not likely to take place + (e.g. slight differences of colour between allied species), + cessation of selection is likely to be very soon assisted by a + failure in the force of heredity; seeing that such newly added + characters will not be so strongly inherited as are the more + ancient characters distinctive of higher taxonomic groups. + + "Let us now turn to Weismann's view of degeneration. First of all, + he has omitted to perceive that 'panmixia' alone (if unassisted + either by reversed selection or an inherent diminishing of the + force of heredity) cannot reduce a functionless organ to the + condition of a _rudiment_. Therefore he everywhere represents + panmixia (or the mere _cessation_ of selection) as of itself + sufficient to cause degeneration, say from 100 to 5, instead of + from 100 to 90 or 80, which, for the reasons above given, appeared + (and still appears) to me about the most that this principle can + accomplish, so long as the original force of heredity continues + unimpaired. No doubt we have here what must be regarded as a mere + oversight on the part of Professor Weismann; but the oversight is + rendered remarkable by the fact that he _does_ invoke the aid of + reversed selection _in order to explain the final disappearance of + a rudiment_. Yet it is self-evident that the reversal of selection + must be much more active during the initial than during the final + stages of degeneration, seeing that, _ex hypothesi_, the greater + the degree of reduction which has been attained the less must be + the detriment arising from any useless expenditure of nutrition, + &c. + + "And this leads me to a second oversight in Professor Weismann's + statement, which is of more importance than the first. For the + place at which he does invoke the assistance of reversed selection + is exactly the place at which reversed selection must necessarily + have ceased to act. This place, as already explained, is where an + obsolescent organ has become rudimentary, or, as above supposed, + reduced to 5 per cent. of its original size; and the reason why he + invokes the aid of reversed selection at this place is in order to + save his doctrine of 'the stability of germ-plasm.' That the force + of heredity should finally become exhausted if no longer + _maintained_ by the _presence_ of selection, is what Darwin's + theory of perishable gemmules would lead us to expect, while such a + fact would be fatal to Weismann's theory of an imperishable + germ-plasm. Therefore he seeks to explain the eventual failure of + heredity (which is certainly a fact) by supposing that after the + point at which the cessation of selection alone can no longer act + (and which his first oversight has placed some 80 per cent. too + low), the reversal of selection will begin to act directly against + the force of heredity as regards the diminishing organ, until such + direct action of reversed selection will have removed the organ + altogether. Or, in his own words, 'The complete disappearance of a + rudimentary organ can only take place by the operation of natural + selection; this principle will lead to its diminution, inasmuch as + the disappearing structure takes the place and the nutriment of + other useful and important organs.' That is to say, the + rudimentary organ finally disappears, not because the force of + heredity is finally exhausted, but because natural selection has + begun to utilize this force against the continuance of the + organ--always picking out those congenital variations of the organ + which are of smallest size, and thus, by its now _reversed_ action, + _reversing_ the force of heredity as regards the organ. + + "Now the oversight here is in not perceiving that the smaller the + disappearing structure becomes, the less hold must 'this principle' + of reversed selection retain upon it. As above observed, during the + earlier stages of reduction (or while co-operating with the + cessation of selection) the reversal of selection will be at its + _maximum_ of efficiency; and, as the process of diminution + continues, a point must eventually be reached at which the reversal + of selection can no longer act. Take the original mass of a now + obsolescent organ in relation to that of the entire organism of + which it then formed a part to be represented by the ratio 1:100. + For the sake of argument we may assume that the mass of the + organism has throughout remained constant, and that by 'mass' in + both cases is meant capacity for absorbing nutriment, causing + weight, occupying space, and so forth. Now, we may further assume + that when the mass of the organ stood to that of its organism in + the ratio of 1:100, natural selection was strongly reversed with + respect to the organ. But when this ratio fell to 1:1000, the + activity of such reversal must have become enormously diminished, + even if it still continued to exercise any influence at all. For we + must remember, on the one hand, that the reversal of selection can + only act as long as the presence of a diminishing organ continues + to be so injurious that variations in its size are matters of life + and death in the struggle for existence; and, on the other hand, + that natural selection in the case of the diminishing organ does + not have reference to the presence and the absence of the organ, + but only to such variations in its mass as any given generation may + supply. Now, the process of reduction does not end even at 1:1000. + It goes on to 1:10,000, and eventually 1:[infinity]. Consequently, + however great our faith in natural selection may be, a point must + eventually come for all of us at which we can no longer believe + that the reduction of an obsolescent organ is due to reversed + selection. And I cannot doubt that if Professor Weismann had + sufficiently considered the matter, he would not have committed + himself to the statement that 'the complete disappearance of a + rudimentary organ can only take place by the operation of natural + selection.' + + "According to my view, the complete disappearance of a rudimentary + organ can only take place by the _cessation_ of natural selection, + which permits the eventual exhaustion of heredity, when heredity is + thus simply left to itself. During all the earlier stages of + reduction, the cessation of selection was assisted in its work by + the reversal of selection; but when the rudiment became too small + for such assistance any longer to be supplied, the rudiment + persisted in that greatly reduced condition until the force of + heredity with regard to it was eventually worn out. This appears to + me, as it appeared in 1873, the only reasonable conclusion that can + be drawn from the facts. And it is because this conclusion is fatal + to Professor Weismann's doctrine of the permanent 'stability' of + germ-plasm, while quite in accordance with all theories which + belong to the family of pangenesis, that I deem the facts of + degeneration of great importance as tests between these rival + interpretations of the facts of heredity. It is on this account + that I have occupied so much space with the foregoing discussion; + and I shall be glad to ascertain whether any of the followers of + Professor Weismann are able to controvert these views. + + "GEORGE J. ROMANES." + + "P.S.--Since the above article was sent in, Professor Weismann has + published in these columns (February 6) his reply to a criticism by + Professor Vines (October 24, 1889). In this reply he appears to + have considerably modified his views on the theory of degeneration; + for while in his Essays he says (as in the passage above quoted) + that 'the complete disappearance of a rudimentary organ can only + take place by the operation of natural selection'--i.e. only by the + _reversal_ of selection,--in his reply to Professor Vines he says, + 'I believe that I have proved that organs no longer in use become + rudimentary, and must finally disappear, solely by 'panmixia'; not + through the direct action of disuse, but because natural selection + no longer sustains their standard structure'--i.e. solely by the + _cessation_ of selection. Obviously, there is here a flat + contradiction. If Professor Weismann now believes that a + rudimentary organ 'must finally disappear _solely_' through the + _withdrawal_ of selection, he has abandoned his previous belief + that 'the complete disappearance of a rudimentary organ can _only_ + take place by the _operation_ of selection.' And this change of + belief on his part is a matter of the highest importance to his + system of theories as a whole, since it betokens a surrender of his + doctrine of the 'stability' of germ-plasm--or of the virtually + everlasting persistence of the force of heredity, and the + consequent necessity for a reversal of this force itself (by + natural selection placing its premium on _minus_ instead of on + _plus_ variations), in order that a rudimentary organ should + finally disappear. In other words, it now seems he no longer + believes that the force of heredity in one direction (that of + sustaining a rudimentary organ) can only be abolished by the active + influence of natural selection determining this force in the + opposite direction (that of removing a rudimentary organ). It seems + he now believes that the force of heredity, if merely left to + itself by the withdrawal of natural selection altogether, will + sooner or later become exhausted through the mere lapse of time. + This, of course, is my own theory of the matter as originally + published in these columns; but I do not see how it is to be + reconciled with Professor Weismann's doctrine of so high a degree + of stability on the part of germ-plasm, that we must look to the + Protozoa and the Protophyta for the original source of congenital + variations as now exhibited by the Metazoa and Metaphyta. + Nevertheless, and so far as the philosophy of degeneration is + concerned, I shall be very glad if (as it now appears) Professor + Weismann's more recent contemplation has brought his principle of + panmixia into exact coincidence with that of my cessation of + selection." + +Before passing on it may here be noted that, to any one who believes in +the inheritance of acquired characters, there is open yet another +hypothetical cause of degeneration, and one to which the final +disappearance of vestigial organs may be attributed. Roux has shown in +his work on _The Struggle for Existence between Parts of an Organism_ +that the principle of selection must operate in every constituent +tissue, and as between every constituent cell of which an organism is +composed. Now, if an organ falls into disuse, its constituent cells +become worsted in their struggles with other cells in the organism. +Hence, degeneration of the disused organ may progressively increase, +quite independently of any struggle for existence on the part of the +organism as a whole. Consequently, degeneration may proceed without any +reference to the principle of "economized nutrition"; and, if it does +so, and if the effects of its doing so are transmitted from generation +to generation, the disused organ will finally disappear by means of +Roux's principle. + +The long communication above quoted led to a still longer correspondence +in the pages of _Nature_. For Professor Ray Lankester wrote[141] to +impugn the doctrine of panmixia, or cessation of selection, _in toto_, +arguing with much insistence that "cessation of selection must be +supplemented by economy of growth in order to produce the results +attributed to panmixia." In other words, he denied that panmixia alone +can cause degeneration in any degree at all; at most, he said, it can be +but "a condition," or "a state," which occurs when an organ or part +ceases to be useful, and therefore falls under the degenerating +influence of active causes, such as economy of nutrition. Or, in yet +other words, he refused to recognize that any degenerative process can +be due to natural selection as merely withdrawn: only when, besides +being _withdrawn_, natural selection is _reversed_, did he regard a +degenerative process as possible. As a result of the correspondence, +however, he eventually[142] agreed that, if the "birth-mean" of an +organ, in respect either of size or complexity of structure, be lower +than the "selection-mean" while the organ is useful (a fact which he +does not dispute); then, if the organ ceases to be useful, it will +degenerate by the withdrawal of selection alone. Which, of course, is +merely a re-statement of the doctrine of panmixia, or cessation of +selection, in somewhat varied terminology--provided that the birth-mean +be taken over a number of generations, or not only over a few following +the selection-mean of the structure while still in its highest state of +efficiency. For the sake of brevity I will hereafter speak of these "few +following" generations by the term of "first generations." + + [141] _Nature_, vol. xli. p. 486. + + [142] _Ibid._ vol. xlii. p. 52. + +It remains to consider the views of Professor Lloyd Morgan upon the +subject. In my opinion he is the shrewdest, as well as the most logical +critic that we have in the field of Darwinian speculation; therefore, if +possible, I should like to arrive at a full agreement with him upon this +matter. His latest utterance with regard to it is as follows:-- + + "To account for the diminution of organs or structures no longer of + use, apart from any inherited effects of disuse, Mr. Romanes has + invoked the Cessation of Selection; and Mr. Francis Galton has, in + another connexion, summarized the effects of this cessation of + selection in the convenient phrase 'Regression to Mediocrity.' This + is the Panmixia of Professor Weismann and his followers; but the + phrase regression to mediocrity through the cessation of selection + appears to me preferable. It is clear that so long as any organ or + structure is subject to natural selection through elimination, it + is, if not actually undergoing improvement, kept at a high standard + of efficiency through the elimination of all those individuals in + which the organ in question falls below the required standard. But + if, from change in the environment or any other cause, the + character in question ceases to be subject to selection, + elimination no longer takes place, and the high standard will no + longer be maintained. There will be reversion to mediocrity. The + probable amount of this reversion is at present a matter under + discussion[143]." + + [143] _Presidential Address to the Bristol Naturalists' Society_, + 1891. + +So far, then, Professor Lloyd Morgan is in complete agreement with +previous writers upon the subject. He does not doubt that the cessation +of selection must always be a cause of degeneration: the only question +is as to the _potency_ of this cause, or the _amount_ of degeneration +which it is capable of effecting. + +Taking, first, the case of bulk or size of an organ, as distinguished +from its organization or complexity, we have seen that Weismann +represents the cessation of selection--even if working quite alone, or +without any assistance from the reversal of selection--to be capable of +reducing a fully developed organ to the state of a rudiment, or even, if +we take his most recent view, of abolishing the organ _in toto_. + +Professor Lloyd Morgan, on the other hand, does not think that the +cessation of selection alone can cause reduction further than the level +of "mediocrity" in the first generations--or, which is much the same +thing, further than the difference between the "birth-mean" and the +"selection-mean" of the first generations. This amount of reduction he +puts at 5 per cent., as "a very liberal estimate." + +Here, then, we have three estimates of the amount of degeneration which +can be produced by panmixia alone, where mere size or bulk of an organ +is concerned--say, 3 to 5 per cent., 10 to 20 per cent., and 95 per +cent. to 0. At first sight, these differences appear simply ludicrous; +but on seeking for the reasons of them, we find that they are due to +different views touching the manner in which panmixia operates. The +oversights which have led to Weismann's extremely high estimate have +already been stated. The reason of the difference between the extremely +low estimate of Professor Lloyd Morgan, as compared with my own +intermediate one, is, that he supposes the power of panmixia to become +exhausted as soon as the level of mediocrity of the first generations +has become the general level in succeeding generations. In my view, +however, the level of mediocrity is itself a sinking level in +successive generations, with the result that there is no reason why the +reducing power of panmixia should ever become exhausted, save that the +more reduction it effects the greater is the force of heredity which +remains to be overcome, as previously explained. Thus the only question +between Professor Lloyd Morgan and myself is--Does the level of +mediocrity fall in successive generations under the cessation of +selection, or does it remain permanently where it used to be under the +presence of selection? Does the "birth-mean" remain constant throughout +any number of generations, notwithstanding that the sustaining influence +of selection has been withdrawn; or does it progressively sink as a +consequence of such withdrawal? + +In order to answer this question we had better begin by considering now +the case of organization of structure, as distinguished from mere size +of structure. Take any case where a complex organ--such as a compound +eye--has been slowly elaborated by natural selection, and is it not +self-evident that, when natural selection is withdrawn, the complex +structure will deteriorate? In other words, the level of mediocrity, say +in the hundred thousandth generation after the sustaining influence of +natural selection has been withdrawn, will not be so high as it was in +the first generations. For, by hypothesis, there is now no longer any +elimination of unfavourable variations, which may therefore perpetuate +themselves as regards any of the parts of this highly complex mechanism; +so that it is only a matter of time when the mechanism must become +disintegrated. I can scarcely suppose that any one who considers the +subject will question this statement, and therefore I will not say +anything that might be said in the way of substantiating it. But, if the +statement be assented to, it follows that there is no need to look for +any cause of deterioration, further than the withdrawal of selection--or +cessation of the principle which (as we are supposing) had hitherto +been the sole means of maintaining efficient harmony among all the +independently variable parts of the highly complex structure. + +Now, I hold that the same thing is true, though in a lesser degree, as +regards degeneration of size. That there is no difference _in kind_ +between the two cases, Professor Lloyd Morgan implicitly allows; for +what he says is-- + + "In any long-established character, such as wing-power in birds, + brain-development, the eyes of crustacea, &c., no shortcomer in + these respects would have been permitted by natural selection to + transmit his shortcomings for hundreds of generations. All tendency + to such shortcomings would, one would suppose, have been bred out + of the race. If after this long process of selection there still + remains a strong tendency to deterioration, this tendency demands + an explanation[144]." + + [144] _Presidential Address to the Bristol Naturalists' Society_, + 1891. + +Here, then, deterioration as to size of structure (wings of birds), and +deterioration as to complexity of structure (brain and eyes) are +expressly put upon the same footing. Therefore, if in the latter case +the "tendency to deterioration" does not "demand an explanation," beyond +the fact that the hitherto maintaining influence has been withdrawn, +neither is any such further explanation demanded in the former case. +Which is exactly my own view of the matter. It is also Mr. Galton's +view. For although, in the passage formerly quoted, Professor Lloyd +Morgan appears to think that by the phrase "Regression to Mediocrity" +Mr. Galton means to indicate that panmixia can cause degeneration only +as far as the mediocrity level of the first generations, this, in point +of fact, is not what Galton means, nor is it what he says. The phrase in +question occurs "in another connexion," and, indeed, in a different +publication. But where he expressly alludes to the cessation of +selection, this is what he says. The italics are mine. + + "A special cause may be assigned for the effects of use in causing + hereditary _atrophy_ of disused parts. It has already been shown + that all exceptionally developed organs tend to deteriorate: + consequently, those that are not _protected_ by selection will + _dwindle_. The level of muscular efficiency in the wing of a + strongly flying bird [curiously enough, the same case that is + chosen by Professor Lloyd Morgan to illustrate his opposite view], + is like the level of water in the leaky vessel of a Danaid, only + secured to the race by _constant effort_, so to speak. _Let the + effort be relaxed ever so little, and the level immediately + falls[145]._" + + [145] _A Theory of Heredity_, Journal of Anthropological Institute, + 1875. Vol. v. p. 345. + +I take it, then, that the burden of proof lies with Professor Lloyd +Morgan to show why the withdrawal of selection is _not_ sufficient to +account for degeneration any further than the mediocrity-level in the +former presence of selection. Why does "the strong tendency[146] to +deterioration demand an explanation," further than the fact that when +all variations below the average in every generation are allowed to +survive, they must gradually lower the average itself through a series +of generations? To answer that any such tendency "would have been bred +out of the race" by the previous action of selection, is to suppose that +the function of selection is at an end when once it has built up a +structure to the highest point of working efficiency,--that the presence +of selection is no longer required to _maintain_ the structure at that +point. But it is enough to ask in reply--Why, under the cessation of +selection, does _complexity_ of structure degenerate so much more +rapidly than _size_ of structure? Why is it, for instance, that "the +eyes of crustacea" in dark caves have entirely disappeared, while their +foot-stalks (when originally present) still remain? Can it be maintained +that "for hundreds of generations" natural selection was more intent on +developing the foot-stalks than the eyes which were mounted upon +them--so that while the latter were left by selection with "a strong +tendency to deterioration," the former have had this tendency "bred out +in the race"[147]? + + [146] No one has supposed that the tendency need be "strong": it has + only to be persistent. + + [147] Of course it must be observed that degeneration of complexity + involves also degeneration of size, so that a more correct + statement of the case would be--Why, under the cessation of + selection, does an organ of extreme complexity degenerate much + more rapidly than one of much less complexity? For example, + under domestication the brains of rabbits and ducks appear to + have been reduced in some cases by as much as 50 per cent. + (Darwin, and Sir J. Crichton Browne.) But if it is possible to + attribute this effect--or part of it--to an artificial + selection of stupid animals, I give in the text an example + occurring under nature. Many other cases, however, might be + given to show the general rule, that under cessation of + selection complexity of structure degenerates more + rapidly--and also more thoroughly--than size of it. This, of + course, is what Mr. Galton and I should expect, seeing that + the more complex a structure the greater are the number of + points for deterioration to invade when the structure is no + longer "protected by selection." (On the other hand, of + course, this fact is opposed to the view that degeneration of + useless structures below the "birth-mean" of the first + generations, is exclusively due to the reversal of selection; + for economy of growth, deleterious effect of weight, and so + forth, ought to affect size of structure _much more_ than + complexity of it.) But I choose the above case, partly because + Professor Lloyd Morgan has himself alluded to "the eyes of + crustacea," and partly because Professor Ray Lankester has + maintained that the loss of these eyes in dark caves is due to + the reversal of selection, as distinguished from the cessation + of it. In view of the above parenthesis it will be seen that + the point is not of much importance in the present connexion; + but it appears to me that cessation of selection must here + have had at least the larger share in the process of atrophy. + For while the economy of nutrition ought to have removed the + relatively large _foot-stalks_ as rapidly as the _eyes_, I + cannot see that there is any advantage, other than the economy + of nutrition, to be gained by the rapid loss of hard-coated + _eyes_, even though they have ceased to be of use. + +To sum up. There is now no question in any quarter touching the fact +that panmixia, or the cessation of selection, is a true cause of +degeneration. The only question is as to the amount of degeneration +which it is able to effect when not assisted by the reversal of +selection, or any other cause of degeneration. Moreover, even with +regard to this question of amount, there is no doubt on any side that +panmixia alone causes degeneration _more rapidly_ where it has to do +with complexity of organization, than it does where it is concerned with +a mere reduction of mass. + +The question as to the amount of degeneration that is caused by the +cessation of selection alone is without any practical importance where +species in a state of nature are concerned, because here the cessation +of selection is probably always associated more or less with the +reversal of it; and it is as impossible as it is immaterial to determine +the relative shares which these two co-operating principles take in +bringing about the observed results. But where organisms in a state of +domestication are concerned, the importance of the question before us is +very great. For if the cessation of selection alone is capable of +reducing an organ through 10 or 12 per cent. of its original size, +nearly all the direct evidence on which Darwin relied in favour of +use-inheritance is destroyed. On the other hand, if reduction through 5 +per cent. be deemed a "very liberal estimate" of what this principle can +accomplish, the whole body of Darwin's direct evidence remains as he +left it. I have now given my reasons for rejecting this lower estimate +on the one band, and what seems to me the extravagant estimate of +Weismann on the other. But my own intermediate estimate is enough to +destroy the apparent proof of use-inheritance that was given by Darwin. +Therefore it remains for those who deny Lamarckian principles, either to +accept some such estimate, or else to acknowledge the incompatibility of +any lower one with the opinion that there is no evidence in favour of +these principles. + + + + +APPENDIX II. + +ON CHARACTERS AS ADAPTIVE AND SPECIFIC. + + +It is the object of this Appendix to state, more fully than in the text, +the opinions with regard to this subject which have been published by +the two highest authorities on the theory of natural selection--Darwin +and Professor Huxley. I will take first the opinion of Professor Huxley, +quoted _in extenso_, and then consider it somewhat more carefully than +seemed necessary in the text. + +As far as I am aware, the only occasion on which Professor Huxley has +alluded to the subject in question, is in his obituary notice of Darwin +in the _Proceedings of the Royal Society_, Vol. XLIV, No. 269, p. xviii. +The allusion is to my paper on _Physiological Selection_, in the +_Journal of the Linnæan Society_, Zool. Vol. XIX, pp. 337-411. But it +will be observed that the criticism has no reference to the theory which +it is the object of that paper to set forth. It refers only to my +definition of the theory of natural selection as primarily a theory of +the origin, or cumulative development, of adaptations. This criticism, +together with my answer thereto at the time, is conveyed in the +following words. + + "Every variety which is selected into a species is favoured and + preserved in consequence of being, in some one or more respects, + better adapted to its surroundings than its rivals. In other words, + every species which exists, exists in virtue of adaptation, and + whatever accounts for that adaptation accounts for the existence of + the species. To say that Darwin has put forward a theory of the + adaptation of species, but not of their origin, is therefore to + misunderstand the first principles of the theory. For, as has been + pointed out, it is a necessary consequence of the theory of + selection that every species must have some one or more structural + or functional peculiarities, in virtue of the advantage conferred + by which it has fought through the crowd of its competitors, and + achieved a certain duration. In this sense, it is true that every + species has been 'originated' by selection." + + Now, in the first place, I have nowhere said that "Darwin has put + forward a theory of the adaptation of species, but not of their + origin." I said, and continue to say, that he has put forward a + theory of _adaptations in general_, and that where such adaptations + appertain to species only (i.e. are peculiar to particular + species), the theory becomes "_also_ a theory of the origin of the + species which present them." The only possible misunderstanding, + therefore, which can here be alleged against me is, that I fail to + perceive it as a "necessary consequence of the theory of selection + that _every_ species _must_ have some one or more structural or + functional _peculiarities_" of an adaptive or utilitarian kind. + Now, if this is a misunderstanding, I must confess to not having + had it removed by Mr. Huxley's exposition. + + The whole criticism is tersely conveyed in the form of two sequent + propositions--namely, "Every species which exists, exists in virtue + of adaptation; and whatever accounts for that adaptation accounts + for the existence of the species." My answer is likewise two-fold. + First, I do not accept the premiss; and next, even if I did, I can + show that the resulting conclusion would not overturn my + definition. Let us consider these two points separately, beginning + with the latter, as the one which may be most briefly disposed of. + + I. Provisionally conceding that "every species which exists, exists + in virtue of adaptation," I maintain that my definition of the + theory of natural selection still holds good. For even on the basis + of this concession, or on the ground of this assumption, the theory + of natural selection is not shown to be "_primarily_" a theory of + the origin of species. It follows, indeed, from the assumption--is, + in fact, part and parcel of the assumption--that all species have + been originated by natural selection; but why? _Only because + natural selection has originated those particular adaptive features + in virtue of which (by the hypothesis) species exist as species._ + It is only in virtue of having created these features that natural + selection has created the species presenting them--just as it has + created genera, families, orders, &c., in virtue of _other_ + adaptive features extending through progressively wider areas of + taxonomic division. Everywhere and equally this principle has been + "primarily" engaged in the evolution of adaptations, and if one + result of its work has been that of enabling the systematist to + trace lines of genetic descent under his divisions of species, + genera, and the rest, such a result is but "secondary" or + "incidental." + + In short, it is "_primarily_" a theory of adaptations _wherever + these occur_, and only becomes "_also_" or "_incidentally_" a + theory of species in cases where adaptations happen to be + restricted in their occurrence to organic types of a certain order + of taxonomic division. + + II. Hitherto, for the sake of argument, I have conceded that, in + the words of my critic, "it is a necessary consequence of the + theory of selection that every species must have some one or more + structural or functional peculiarities" of an adaptive kind. But + now I will endeavour to show that this statement does not "follow + as a necessary consequence" from "the theory of selection." + + Most obviously "it follows" from the theory of selection that + "every variety which is selected into a species is favoured and + preserved in consequence of being, in some one or more respects, + better adapted to its surroundings than its rivals." This, in fact, + is no more than a re-statement of the theory itself. But it does + _not_ follow that "every species which exists, exists in virtue of + adaptation" _peculiar to that species_; i.e. that every species + which exists, exists _in virtue of having been "selected_." This + may or may not be true as a matter of fact: as a matter of logic, + the inference is not deducible from the selection theory. Every + variety which is "_selected into_" a species must, indeed, present + some such peculiar advantage; but this is by no means equivalent to + saying, "in other words," that every variety which _becomes_ a + species must do so. For the latter statement imports a completely + new assumption--namely, that every variety which _becomes_ a + species must do so because it has been "_selected into_" a species. + In short, what we are here told is, that if we believe the + selection principle to have given origin to some species, we must + further believe, "as a necessary consequence," that it has given + origin to all species. + +The above reply, which is here quoted _verbatim_ from _Nature_, Vol. 38, +p. 616-18, proceeded to show that it does not belong to "the first +principles of the theory of natural selection" to deny that no other +cause than natural selection can possibly be concerned in the origin of +species; and facts were given to prove that such unquestionably has been +the case as regards the origin of "local" or "permanent" _varieties_. +Yet such varieties are what Darwin correctly terms "incipient" species, +or species in process of taking _origin_. Therefore, if Professor +Huxley's criticism is to stand at all, we must accept it "as a necessary +consequence of the theory of selection," that every such _variety_ +"which exists, exists in virtue of adaptation"--a statement which is +_proved_ to be untrue by the particular cases forthwith cited. But as +this point has been dealt with much more fully in the text of the +present treatise, I shall sum up the main points in a few words. + +The criticism is all embodied in two propositions--namely, (_a_) that +the theory of natural selection carries with it, as a "necessary +consequence," the doctrine that survival of the fittest has been the +cause of the origin of _all_ species; and (_b_) that therefore it +amounts to one and the same thing whether we define the theory as a +theory of species or as a theory of adaptations. Now, as a mere matter +of logical statement, it appears to me that both these propositions are +unsound. As regards the first, if we hold with Darwin that other causes +have co-operated with natural selection in the origination of some (i. +e. many) species, it is clearly no part of the theory of natural +selection to assume that none of these causes can ever have acted +independently. In point of fact, as we have seen in the foregoing +chapters, such has probably and frequently been the case under the +influences of isolation, climate, food, sexual selection, and laws of +growth; but I may here adduce some further remarks with regard to yet +another possible cause. If the Lamarckian principles are valid at all, +no reason can be shown why in some cases they may not have been +competent _of themselves_ to induce morphological changes of type by +successive increments, until a transmutation of species is effected by +their action alone--as, indeed, Weismann believes to have been the case +with all the species of Protozoa[148]. That such actually has often been +the case also with numberless species of Metozoa, is the belief of the +neo-Lamarckians; and whether they are right or wrong in holding this +belief, it is equally certain that, _as a matter of logical reasoning_, +they are not compelled by it to profess any _disbelief_ in the agency of +natural selection. They may be mistaken as to the facts, as Darwin in a +lesser degree may have been similarly mistaken; but just as Darwin has +nowhere committed himself to the statement that _all_ species must +_necessarily_ have been originated by natural selection, so these +neo-Lamarckians are perfectly logical in holding that _some_ species may +have been wholly caused by the inheritance of acquired characters, as +_other_ species may have been wholly caused by the natural selection of +congenital characters. In short, unless we begin by assuming (with +Wallace and against Darwin) that there _can be no other cause_ of the +origin of species than that which is furnished by natural selection, we +have no basis for Professor Huxley's statement "that every species has +been originated by selection"; while, if we do set out with this +assumption, we end in a mere tautology. What ought to be done is to +prove the validity of this assumption; but, as Professor Huxley makes +no attempt to do this, his criticism amounts to mere begging of the +question. + + [148] Since the above was written Professor Weismann has transferred + this doctrine from the Protozoa to their ancestors. + +And now, as regards the second point (_b_), even if we grant the +assumption that natural selection is the only possible cause of the +origin of species--or, which is the same thing, that every species has +been originated by natural selection,--is it likewise the same thing +whether we define the theory of natural selection as a theory of species +or as a theory of adaptations? Professor Huxley's criticism endeavours +to show that it is; but a little consideration is enough to show that it +is not. What does follow from the assumption is, that, _so far as +specific characters are concerned_, it is one and the same thing to say +that the theory is a theory of species, and to say that it is a theory +of adaptations. But specific characters are not conterminous with +adaptive characters; for innumerable adaptive characters are not +distinctive of species, but of genera, families, orders, classes, and +sub-kingdoms. Therefore, if it is believed (as, of course, Professor +Huxley believes) that the theory in question explains the evolution of +all adaptive characters, obviously it is not one and the same thing to +define it indifferently as a theory of species or as a theory of +adaptations. + +Now, all this is not merely a matter of logic chopping. On the contrary, +the question whether we are to accept or to reject the deduction that +all species must necessarily have owed their origin to natural +selection, is a question of no small importance to the general theory of +evolution. And our answer to this question must be determined by that +which we give to the ulterior question--Is the theory of natural +selection to be defined as a theory of species, or as a theory of +adaptations? + + * * * * * + +We now pass on to our consideration of Darwin's opinion touching the +question, as stated by himself,--"The doctrine of utility, how far +true?" As I cannot ascertain that Darwin has anywhere expressed an +opinion as to whether natural selection has been necessarily concerned +in the origin of all _species_, the issue here is as to whether he held +this with regard to all _specific characters_. It will be remembered +that while opposing this doctrine as erroneous both in logic and in +fact, I have represented that it is not a doctrine which Darwin +sanctioned; but, on the contrary, that it is one which he expressly +failed to sanction, by recognizing the frequent inutility of specific +characters. Mr. Wallace, on the other hand, alleges that Darwin did +believe in the universal--as distinguished from the general--utility of +such characters. And he adds that he has "looked in vain in Mr. Darwin's +works" for any justification of my statements to the contrary[149]. +Therefore I will endeavour to show that Mr. Wallace's search has not +been a very careful one. + + [149] _Darwinism_, p. 131. He says:--"I have looked in vain in Mr. + Darwin's works for any such acknowledgement" (i.e. "that a + large proportion of specific distinctions must be conceded + useless to the species presenting them"). + +We must remember, however, that it was not until the appearance of my +paper on _Physiological Selection_, four years after Darwin's death, +that the question now in debate was raised. Consequently, he never had +occasion to deal expressly with this particular question--viz. whether +"the doctrine of utility" has any _peculiar_ reference to _specific_ +characters--as he surely would have done had he entertained the +important distinction between specific and all other characters which +Mr. Wallace now alleges that he did entertain. But, be this as it may, +we cannot expect to find in Darwin's writings any express allusion to a +question which had not been raised until 1886. The most we can expect to +find are scattered sentences which prove that the distinction in +question was never so much as present to his mind,--i. e. never occurred +to him as even a possible distinction. + +I will first take the passages which Mr. Wallace himself supplies from +among those which I had previously indicated. + + "But when, from the nature of the organism and of the conditions, + modifications have been induced which are unimportant for the + welfare of the _species_, they may be, and apparently often have + been, transmitted in nearly the same state to numerous, otherwise + modified, descendants[150]." + + [150] _Origin of Species_, p. 175. Italics mine. + +On this passage Mr. Wallace remarks that the last five words "clearly +show that such characters are usually not 'specific,' in the sense that +they are such as distinguish species from one another, but are found in +numerous allied species." But I cannot see that the passage shows +anything of the sort. What to my mind it does show is, (_a_) that Mr. +Darwin repudiated Mr. Wallace's doctrine touching the _necessary_ +utility of _all_ specific characters: (_b_) that he takes for granted +the contrary doctrine touching the inutility of _some_ specific +characters: (_c_) that without in this place alluding to the +proportional number of useless specific characters, he refers their +origin in some cases to "the nature of the organism" (i.e. "spontaneous +variability" due to internal causes), and in other cases to "the +conditions" (i.e. variability induced by external causes): (_d_) that +when established as a specific character by heredity, such a useless +character was held by him not to tend to become obsolete by the +influence of natural selection or any other cause; but, on the contrary, +to be "transmitted in nearly the same state to numerous, otherwise +modified, descendants"--or progeny of the species in genera, families, +&c.: (_e_) and, therefore, that useless characters which are now +distinctive of genera, families, &c., were held by him frequently, if +not usually, to point to uselessness of origin, when first they arose as +merely specific characters. Even the meaning which Mr. Wallace reads +into this passage must imply every one of these points; and therefore I +do not see that he gains much by apparently seeking to add this further +meaning--viz. that in Darwin's opinion there must have been some +unassignable reason preventing the occurrence of useless specific +characters in cases where species are _not_ destined to become the +parents of genera. + +Moreover, any such meaning is out of accordance with the context from +which the passage is taken. For, after a long consideration of the +question of utility, Darwin sums up,--"We thus see that with plants many +morphological changes may be attributed to the laws of growth and the +interaction of parts, _independently of natural selection_." And then he +adds,--"From the fact of the above characters being _unimportant for the +welfare of the species_, any slight variations which occurred in them +_would not have been augmented through natural selection_." Again, still +within the same passage, he says, while alluding to the causes other +than natural selection which lead to changes of specific +characters,--"If the _unknown cause_ were to act almost uniformly for a +length of time, we may infer that the result would be almost uniform; +and in this case _all_ the individuals of the _species_ would be +modified in the same manner." For my own part I do not understand how +Mr. Wallace can have overlooked these various references to _species_, +all of which occur on the very page from which he is quoting. The whole +argument is to show that "many morphological changes may be attributed +to the laws of growth and the inter-action of parts [_plus_ external +conditions of life], independently of natural selection"; that such +non-adaptive changes, when they occur as "specific characters," may, if +the species should afterwards give rise to genera, families, &c., become +distinctive of these higher divisions. But there is nothing here, or in +any other part of Darwin's writings, to countenance the inconsistent +notion which Mr. Wallace appears to entertain,--viz. that species which +present useless characters are more apt to give rise to genera, +families, &c., than are species which do not present such characters. + +The next passage which Mr. Wallace quotes, with his comments thereon, is +as follows. The italics are his. + + "'Thus a large yet undefined extension may safely be given to the + direct and indirect results of natural selection; but I now admit, + after reading the essay of Nägeli on plants, and the remarks by + various authors with respect to animals, more especially those + recently made by Professor Broca, that in the earlier editions of + my Origin of Species I perhaps attributed too much to the action of + natural selection, or the survival of the fittest. I have altered + the fifth edition of the Origin so as to confine my remarks to + adaptive changes of structure; _but I am convinced, from the light + gained during even the last few years, that very many structures + which now appear to be useless, will hereafter be proved to be + useful, and will therefore come within the range of natural + selection_. Nevertheless I did not formerly consider sufficiently + the existence of structures which, as far as we can at present + judge, are neither beneficial nor injurious; and this I believe to + be one of the greatest oversights as yet detected in my work.' + + Now it is to be remarked that neither in these passages nor in any + of the other less distinct expressions of opinion on this question, + does Darwin ever admit that "specific characters"--that is, the + particular characters which serve to distinguish one species from + another--are ever useless, much less that "a large proportion of + them" are so, as Mr. Romanes makes him "freely acknowledge." On the + other hand, in the passage which I have italicised he strongly + expresses his view that much of what we suppose to be useless is + due to our ignorance; and as I hold myself that, as regards many of + the supposed useless characters, this is the true explanation, it + may be well to give a brief sketch of the progress of knowledge in + transferring characters from the one category to the other[151]." + + [151] _Darwinism_, p. 132. + +It is needless to continue this quotation, because of course no one is +disputing that an enormous number of specific characters whose utility +is unknown are nevertheless useful, and therefore due to natural +selection. In other words, the question is not--Are there not many +useful specific characters whose utility is unknown? but--Does it follow +from the theory of natural selection that all specific characters must +necessarily be useful? Well, it appears to me that without going further +than the above passage, which Mr. Wallace has quoted, we can see clearly +enough what was Darwin's opinion upon the subject. He did not believe +that it followed _deductively_ from his theory that all specific +characters must necessarily be useful; and therefore he regarded it as a +question of _fact_--to be determined by induction as distinguished from +deduction--in what proportional number of cases they are so. Moreover he +gives it as his more matured opinion, that, "as far as we can at present +judge" (i.e. from the present state of observation upon the subject: if, +with Mr. Wallace, his judgement were _a priori_, why this +qualification?), he had not previously sufficiently considered the +existence of non-adaptive characters--and this he ended by believing was +one of the greatest oversights as yet detected in his work. To me it has +always seemed that this passage is one of the greatest exhibitions of +candour, combined with solidity of judgement, that is to be met with +even in the writings of Darwin. There is no talk about any deductive +"necessity"; but a perfect readiness to allow that causes other than +natural selection may have been at work in evoking non-adaptive +characters, so that the fifth edition of the _Origin of Species_ was +altered in order to confine the theory of natural selection to "adaptive +changes"--i.e. to constitute it, as I have said in other words, "a +theory of the origin, or cumulative development, of _adaptations_." + +If to this it be said that in the above passage there is no special +mention of _species_, the quibble would admit of a three-fold reply. In +the first place, the quibble in question had never been raised. As +already stated, it is only since the appearance of my own paper on +_Physiological Selection_ that anybody ever thought of drawing a +distinction between species and genera, such that while all specific +characters must be held necessarily useful, no such necessity extends to +generic characters. In the second place, that Darwin must have had +specific characters (as well as generic) in his mind when writing the +above passage, is rendered unquestionable by the fact that many of the +instances of inutility adduced by Nägeli and Broca have reference to +specific characters. Lastly, as shown in the passages previously quoted +from the sixth edition of the _Origin of Species_, Darwin attributed the +origin of useless generic characters to useless specific characters; so +that Mr. Wallace really gains nothing by his remark that specific +characters are not specially mentioned in the present passage. + +Once more:-- + + "Darwin's latest expression of opinion on this question is + interesting, since it shows he was inclined to return to his + earlier view of the general, or universal, utility of specific + characters[152]." + + [152] _Darwinism_, p. 142. + +This "latest expression of opinion," as I shall immediately prove, shows +nothing of the kind--being, in fact, a mere re-statement of the opinion +everywhere and at all times expressed by Darwin, touching the caution +that must be observed in deciding, _with respect to individual cases_, +whether an apparently useless specific character is to be regarded as +really useless. Moreover, at no time and in no place did Darwin +entertain any "view of the general, or universal, utility of specific +characters." But the point now is, that if (as was the case) Darwin +"inclined" to depart more and more from his earlier view of the highly +_general_ utility of specific characters; and if (as was not the case) +he ended by showing an inclination "_to return_" to this earlier view; +what becomes of the whole of Mr. Wallace's contention against which +this Appendix is directed, namely, _that Darwin never entertained any +other view than that of the "general, or universal, utility of specific +characters_"? + +The "latest expression of opinion" which Mr. Wallace quotes, occurs in a +letter written to Professor Semper in 1878. It is as follows:-- + + "As our knowledge advances, very slight differences, considered by + systematists as of no importance in structure, are continually + found to be functionally important; and I have been especially + struck with this fact in the case of plants, to which my + observations have of late years been confined. Therefore it seems + to me rather rash to consider the slight differences between + representative species, for instance those inhabiting the different + islands of the same archipelago, as of no functional importance, + and as not in any way due to natural selection[153]." + + [153] _Life and Letters_, vol. iii. p. 161. + +Now, with regard to this passage it is to be observed, as already +remarked, that it refers to the formation of final judgements touching +_particular cases_: there is nothing to show that the writer is +contemplating _general principles_, or advocating on deductive grounds +the dogma that specific characters must be necessarily and universally +adaptive characters. Therefore, what he here says is neither more nor +less than I have said. For I have always held that it would be "rather +rash" to conclude that any given cases of apparent inutility are +certainly cases of real inutility, _merely on the ground that utility is +not perceived_. But this is clearly quite a distinct matter from +resisting the _a priori_ generalization that all cases of apparent +inutility must certainly be cases of real utility. And, I maintain, in +every part of his writings, without any exception, where Darwin alludes +to this matter of general principle, it is in terms which directly +contradict the deduction in question. As the whole of this Appendix has +been directed to proving that such is the case, it will now, I think, be +sufficient to supply but one further quotation, in order to show that +the above "latest expression of opinion," far from indicating that in +his later years Darwin "inclined" to Mr. Wallace's views upon this +matter, is quite compatible with a distinct "expression of opinion" to +the contrary, in a letter written less than six years before his death. + + "In my opinion _the greatest error which I have committed_, has + been not allowing sufficient weight to the direct action of the + environment, i.e. food, climate, &c., _independently of natural + selection_. Modifications thus caused, _which are neither of + advantage nor disadvantage to the modified organisms_, would be + especially favoured, as I can now see chiefly through your + observations, _by isolation in a small area, where only a few + individuals lived under nearly uniform conditions_[154]." + + [154] _Life and Letters_, vol. iii. p. 158. + +I will now proceed to quote further passages from Darwin's works, which +appear to have escaped the notice of Mr. Wallace, inasmuch as they admit +of no doubt regarding the allusions being to _specific_ characters. + + "_We may easily err in attributing importance to characters, and in + believing that they have been developed through natural selection._ + We must by no means overlook the effects of the definite action of + changed conditions of life,--of so-called spontaneous variations, + which seem to depend in a quite subordinate degree on the nature of + the conditions,--of the tendency to reversion to long-lost + characters,--of the complex laws of growth, such as of + correlation[155], compensation, of pressure of one part on another, + &c., and finally of sexual selection, by which characters of use to + one sex are often gained and then transmitted more or less + perfectly to the other sex, though of no use to this sex. But + structures thus indirectly gained, _although at first of no + advantage to a species_, may subsequently have been taken advantage + of by its modified descendants, under new conditions of life and + newly acquired habits[156]." + + [155] It must be observed that Darwin uses this word, not as Mr. + Wallace always uses it (viz. as if correlation can only be + with regard to adaptive characters), but in the wider sense + that any change in one part of an organism--whether or not it + happens to be an adaptive change--is apt to induce changes in + other parts. + + [156] _Origin of Species_, pp. 157-8. + +It appeared--and still appears--to me, that where so many causes are +expressly assigned as producing useless _specific_ characters, and that +some of them (such as climatic influences and independent variability) +must be highly general in their action, I was justified in representing +it as Darwin's opinion that "a large proportional number of specific +characters" are useless to the _species_ presenting them, although +afterwards they may sometimes become of use to genera, families, &c. +Moreover, this passage goes on to point out that specific characters +which at first sight appear to be obviously useful, are sometimes found +by fuller knowledge to be really useless--a consideration which is the +exact inverse of the argument from ignorance as used by Mr. Wallace, and +serves still further to show that in Darwin's opinion utility is by no +means an invariable, still less a "necessary," mark of specific +character. The following are some of the instances which he gives. + + "The sutures in the skulls of young mammals have been advanced as a + beautiful adaptation for aiding parturition, and no doubt they may + facilitate, or be indispensable for this act; but as sutures occur + in the skulls of young birds and reptiles, which have only to + escape from a broken egg, we may infer that this structure has + _arisen from the laws of growth_, and has been taken advantage of + in the parturition of the higher animals[157]." + + "The naked skin on the head of a vulture is generally considered as + a direct adaptation for wallowing in putridity; and so it may be, + _or it may possibly be due to the direct action of the putrid + matter_; but we should be very cautious in drawing any such + inference [i.e. as to utility] when we see the skin on the head of + the clean-feeding male Turkey is likewise naked[158]." + + [157] _Ibid._ + + [158] _Origin of Species_, pp. 157-8. + +Similarly, in the _Descent of Man_ it is said:-- + + "Variations of the same _general_ nature have _often been taken + advantage of_ and accumulated through sexual selection in relation + to the propagation of the species, and through natural selection in + relation to the general purposes of life. Hence, _secondary sexual + characters, when equally transmitted to both sexes, can be + distinguished from ordinary specific characters, only by the light + of analogy_. The modifications acquired through sexual selection + are often so strongly pronounced that the two sexes have frequently + been ranked as distinct species, or even as distinct genera[159]." + + [159] _Descent of Man_, p. 615. + +As Mr. Wallace does not recognize sexual selection, he incurs the burden +of proving utility (in the life-preserving sense) in all these +"frequently" occurring cases where there are such "strongly pronounced +modifications," and we have already seen in the text his manner of +dealing with this burden. But the point here is, that whether or not we +accept the theory of sexual selection, we must accept it as Darwin's +opinion--first, that in their beginnings, as _specific_ characters, +these sexual modifications were often of a merely "_general nature_" (or +without reference to utility even in the life-embellishing sense), and +only _afterwards_ "have often been taken advantage of and accumulated +through _sexual_ selection": and, secondly, that "we know they have been +acquired in some instances _at the cost not only of inconvenience, but +of exposure to actual dangers_[160]." + + [160] _Ibid._ + +We may now pass on to some further, and even stronger, expressions of +opinion with regard to the frequent inutility of _specific_ characters. + + "I have made these remarks only to show that, if we are unable to + account for the characteristic differences of our several domestic + breeds, which nevertheless are generally admitted to have arisen + through ordinary generation from one or a few parent stocks, we + ought not to lay too much stress on our ignorance of the precise + cause [i.e. whether natural selection or some other cause] of the + slight analogous differences between true _species_.... I fully + admit that _many_ structures are now of no use to their possessors, + and may never have been of any use to their progenitors; but this + does not prove that they were formed solely for beauty or variety. + No doubt the definite action of changed conditions, and the various + causes of modification, lately specified, have all produced an + effect, _probably a great effect, independently of any advantage + thus gained_.... It is scarcely possible to decide how much + allowance ought to be made for such causes of change, as the + definite action of external conditions, so-called spontaneous + variations, and the complex laws of growth; but, _with these + important exceptions_, we may conclude that the structure of every + living creature either now is, or formerly was, of some direct or + indirect use to its possessor[161]." + + [161] _Descent of Man_, pp. 159-60. + +Here again, if we remember how "important" these "exceptions" are, I +cannot understand any one doubting Darwin's opinion to have been that a +large proportional number of specific characters are useless. For that +it is "species" which he here has mainly in his mind is evident from +what he says when again alluding to the subject in his "Summary of the +Chapter"--namely, "In _many_ other cases [i.e. in cases where natural +selection has not been concerned] modifications are probably the direct +result of the laws of variation or of growth, independently of any good +having been thus gained." Now, not only do these "laws" apply as much to +species as they do to genera; "but," the passage goes on to say, "even +such structures have often, we may feel assured, been subsequently +taken advantage of, and still further modified, for the good of +_species_ under new conditions of life." Obviously, therefore, the +inutility in such cases is taken to have been prior to any utility +subsequently acquired; and genera are not historically prior to the +species in which they originate. + +Here is another quotation:-- + + "Thus, as I am inclined to believe, morphological differences, + which we consider as important--such as the arrangement of the + leaves, the divisions of the flower or of the ovarium, the position + of the ovules, &c.--_first_ appeared in _many_ cases as + _fluctuating variations_, which sooner or later became constant + through the nature of the organism and of the surrounding + conditions, as well as through the intercrossing of distinct + individuals, _but not through natural selection_; for as these + morphological characters do not affect the welfare of the + _species_, any slight deviations in them could not have been + governed or accumulated through this latter agency. It is a strange + result which we thus arrive at, namely, that characters of slight + vital importance to the _species_, are the most important to the + systematist; but, as we shall hereafter see when we treat of the + genetic principle of classification, this is by no means so + paradoxical as it may at first appear[162]." + + [162] _Descent of Man_, p. 176. + +Clearly the view here expressed is that characters which are now +distinctive of higher taxonomic divisions "first appeared" in the parent +species of such divisions; for not only would it be unreasonable to +attribute the rise and preservation of useless characters to +"fluctuating variations" affecting a number of species or genera +similarly and simultaneously; but it would be impossible that, if such +were the case, they could be rendered "constant through the nature of +the organism and of the surrounding conditions, as well as through the +intercrossing of distinct individuals[163]." + + [163] The passage to which these remarks apply is likewise quoted, + in the same connexion as above, in my paper on _Physiological + Selection_. In criticising that paper in _Nature_ (vol. xxxix. + p. 127), Mr. Thiselton Dyer says of my interpretation of this + passage, "the obvious drift of this does not relate to + specific differences, but to those which are characteristic of + family." But in making this remark Mr. Dyer could not have + read the passage with sufficient care to note the points which + I have now explained. + +Here is another passage to the same general effect. In alluding to the +objection from inutility as advanced by Bronn, Broca, and Nägeli, Mr. +Darwin says:--"There is much force in the above objection"; and, after +again pointing out the important possibility in any particular cases of +hidden or former use, and the action of the laws of growth, he goes on +to say,--"In the third place, we have to allow for the direct and +definite action of changed conditions of life, and for so-called +spontaneous variations, in which the nature of the conditions plays +quite a subordinate part[164]." Elsewhere he says,--"It appears that I +formerly underrated the frequency and value of these latter forms of +variation as leading to permanent modifications of structure +_independently of natural selection_[165]." The "forms of variation" to +which he here alludes are "variations which seem to us in our ignorance +to arise spontaneously"; and it is evident that such variations cannot +well "arise" in two or more species of a genus similarly and +simultaneously, so as independently to lead "to permanent modifications +of structure" in two or more parallel lines. It is further evident that +by "spontaneous variations" Darwin alludes to extreme cases of +spontaneous departure from the general average of specific characters; +and therefore that lesser or more ordinary departures must be of still +greater "frequency." + + [164] _Origin of Species_, p. 171. + + [165] _Ibid._ p. 421. + +Again, speaking of the principles of classification, Darwin writes:-- + + "We care not how trifling a character may be--let it be the mere + inflection of the angle of the jaw, the manner in which an + insect's wing is folded, whether the skin be covered by hair or + feathers--if it prevail throughout many and different species, + especially those having very different habits of life, it assumes + high value [i.e. for purposes of classification]; for we can + account for its presence in so many forms with such _different + habits_, only by inheritance from a common parent. We may err in + this respect in regard to single points of structure, but when + several characters, let them be ever so trifling, concur throughout + a large group of beings _having different habits_, we may feel + almost sure, on the theory of descent, that these characters have + been inherited from a common ancestor; and we know that such + aggregated characters have especial value in classification[166]." + + [166] _Origin of Species_, pp. 372-373. + +Now it is evident that this argument for the general theory of evolution +would be destroyed, if Wallace's assumption of utility of specific +characters as universal were to be entertained. And the fact of +apparently "trifling" characters occurring throughout a large group of +beings "having different habits" is proof that they are really trifling, +or without utilitarian significance. + +It is needless to multiply these quotations, for it appears to me that +the above are amply sufficient to establish the only point with which we +are here concerned, namely, that Darwin's opinion on the subject of +utility in relation to specific characters was substantially identical +with my own. And this is established, not merely by the literal meaning +of the sundry passages here gathered together from different parts of +his writings; but likewise, and perhaps still more, from the tone of +thought which pervades these writings as a whole. It requires no words +of mine to show that the literal meaning of the above quotations is +entirely opposed to Mr. Wallace's view touching the _necessary_ utility +of _all_ specific characters; but upon the other point--or the general +tone of Mr. Darwin's thought regarding such topics--it may be well to +add two remarks. + +In the first place, it must be evident that so soon as we cease to be +bound by any _a priori_ deduction as to natural selection being "the +exclusive means of modifications," it ceases to be a matter of much +concern to the theory of natural selection in what proportion other +means of modification have been at work--especially when non-adaptive +modifications are concerned, and where these have reference to merely +"specific characters," or modifications of the most incipient kind, +least generally diffused among organic types, and representing the +incidence of causes of less importance than any others in the process of +organic evolution considered as a whole. Consequently, in the second +place, we find that Darwin nowhere displays any solicitude touching the +proportional number of specific characters that may eventually prove to +be due to causes other than natural selection. He takes a much wider and +deeper view of organic evolution, and, having entirely emancipated +himself from the former conception of species as the organic units, sees +virtually no significance in specific characters, except in so far as +they are also adaptive characters. + +Such, at all events, appears to me the obvious interpretation of his +writings when these are carefully read with a view to ascertaining his +ideas upon "Utilitarian doctrine: how far true." And I make these +remarks because it has been laid to my charge, that in quoting such +passages as the above I have been putting "a strained interpretation" +upon Darwin's utterances: "such admissions," it is said, "Mr. Romanes +appears to me to treat as if wrung from a hostile witness[167]." But, +from what has gone before, it ought to be apparent that I take precisely +the opposite view to that here imputed. Far from deeming these and +similar passages as "admissions wrung from a hostile witness," and far +from seeking to put any "strained interpretation" upon them, I believe +that they are but the plain and unequivocal expressions of an opinion +which I have always understood that Darwin held. And if any one has been +led to think otherwise, I throw back this charge of "strained +interpretation," by challenging such a person to adduce a single +quotation from any part of Darwin's works, which can possibly be held to +indicate that he regarded passages like those above quoted as in any way +out of conformity with his theory of natural selection--or as put +forward merely to "admit the possibility of explanations, to which +really, however, he did not attach much importance." To the best of my +judgement it is only some bias in favour of Mr. Wallace's views that can +lead a naturalist to view in this way the clear and consistent +expression of Darwin's. + + [167] Mr. Thiselton Dyer in _Nature_, _loc. cit._ + +That Mr. Wallace himself should be biassed in this matter might, +perhaps, be expected. After rendering the following very unequivocal +passage from the _Origin of Species_ (p. 72)--"There can be little doubt +that the tendency to vary in the same manner has often been so strong, +_that all individuals of the same species have been similarly modified +without the aid of any form of selection_"--Mr. Wallace says, "But no +proof whatever is offered of this statement, and it is so entirely +opposed to all we know of the facts of variation as given by Darwin +himself, that the important word 'all' is probably an oversight." But, +if Mr. Wallace had read the very next sentence he would have seen that +here the important word "all" could not _possibly_ have been "an +oversight." For the passage continues,--"Or only a third, fifth, or +tenth part of the individuals may have been thus affected, of which fact +several instances could be given. Thus Graba estimates that about +one-fifth of the guillemots in the Faroe Islands consist of a variety so +well marked, that it was formerly ranked as a distinct species under the +name of Uria lacrymans." And even if this passage had not been thus +specially concerned with the question of the _proportion_ in which +"_individuals of the same species have been similarly modified without +the aid of any form of selection_" the oversight with respect to "the +important word 'all'" would still have remained an oversight of a +recurrent character, as the following additional quotations from other +parts of Darwin's writings may perhaps render apparent. + + "There must be some efficient cause for each slight individual + difference, as well as for more strongly marked variations which + occasionally arise; and if the unknown cause were to act + persistently, it is almost certain that _all_ the individuals of + the _species_ would be similarly modified[168]." + + "The acquisition of a useless part can hardly be said to raise an + organism in the natural scale.... We are so ignorant of the + exciting cause of the above specified modifications; but if the + unknown cause were to act almost uniformly for a length of time, we + may infer that the result would be almost uniform; and in this case + _all_ the individuals of the _species_ would be modified in the + same manner[169]." + + [168] _Origin of Species_, p. 171. + + [169] _Ibid._ p. 175. + +Moreover, when dealing even with such comparatively slight changes as +occur between our domesticated varieties--and which, _a fortiori_, are +less likely to become "stable" through the uniform operation of causes +other than selection, seeing that they are not only smaller in amount +than occurs among natural species, but also have had but a comparatively +short time in which to accumulate--Darwin is emphatic in his assertion +of the same principles. For instance, in the twenty-third chapter of the +_Variation of Plants and Animals under Domestication_, he repeatedly +uses the term "definite action of external conditions," and begins the +chapter by explaining his use of the term thus:-- + + "By the term definite action, as used in this chapter, I mean an + action of such a nature that, when many individuals of the same + variety are exposed during several generations to any change in + their physical conditions of life, _all_, or _nearly all_, the + individuals are modified in the same manner. A new _sub-variety_ + would thus be produced _without the aid of selection_[170]." + + [170] _Variation_, &c., vol. ii. p. 260. + +As an example of the special instances that he gives, I may quote the +following from the same work:-- + + "Each of the endless variations which we see in the plumage of our + fowls must have had some efficient cause; and if the same cause + were to act uniformly during a long series of generations on many + individuals, _all_ probably would be modified in the same manner." + +And, as instances of his more general statements in Chapter XXIII, these +may suffice:-- + + "The direct action of the conditions of life, whether leading to + definite or indefinite results, _is a totally distinct + consideration from the effects of natural selection_.... The direct + and definite action of changed conditions, in contradistinction to + the accumulation of indefinite variations, _seems to me so + important_ that I will give a large additional body of + miscellaneous facts[171]." + + [171] _Ibid._ vol. ii. p. 261. + +Then, after giving these facts, and showing how in the case of species +in a state of nature it is often impossible to decide how much we are to +attribute to natural selection and how much to the definite action of +changed conditions, he begins his general summary of the chapter thus:-- + + "There can be no doubt, from the facts given in the early part of + this chapter, that extremely slight changes in the conditions of + life sometimes act in a definite manner on our already variable + domesticated productions [productions, therefore, with regard to + which uniformity and 'stability' of modification are least likely + to arise]; and, as the action Of changed conditions in causing + general or indefinite variability is accumulative, so it may be + with their definite action. Hence it is possible that _great_ and + _definite_ modifications of structure may result from altered + conditions acting during a long series of generations. In some few + instances a marked effect has been produced quickly on _all_, or + _nearly all_, the individuals which have been exposed to some + considerable change of climate, food, or other circumstance[172]." + + [172] _Variation_, &c., vol. ii. p. 280. + +Once more, in order to show that he retained these views to the end of +his life, I may quote a passage from the second edition of the _Descent +of Man_, which is the latest expression of his opinion upon these +points:-- + + "Each of the endless diversities in plumage, which we see in our + domesticated birds, is, of course, the result of some definite + cause; and under natural and more uniform conditions, some one + tint, _assuming that it was in no way injurious, would almost + certainly sooner or later prevail_. The free-intercrossing of the + many individuals belonging to the same species would ultimately + tend to make any change of colour thus induced _uniform in + character_.... Can we believe that the very slight differences in + tints and markings between, for instance, the female black-grouse + and red-grouse serve as a protection? Are partridges as they are + now coloured, better protected than if they had resembled quails? + Do the slight differences between the females of the common + pheasant, the Japan and golden pheasants, serve as a protection, or + might not their plumage have been interchanged with impunity? From + what Mr. Wallace has observed of the habits of certain gallinaceous + birds in the East, he thinks that such slight differences are + beneficial. For myself, I will only say, I am not convinced[173]." + + [173] _Descent of Man_, pp. 473-4. + +Yet "convinced" he certainly must have been on merely _a priori_ +grounds, had he countenanced Mr. Wallace's reasoning from the general +theory of natural selection; and the fact that he here fails to be +convinced even by "what Mr. Wallace has observed of the habits of +certain gallinaceous birds," appears to indicate that he had considered +the question of utility with special reference to Mr. Wallace's opinion. +That opinion was then, as now, the avowed result of a theoretical +prepossession; and this prepossession, as the above quotations +sufficiently show, was expressly repudiated by Darwin. + +Lastly, this is not the only occasion on which Darwin expressly +repudiates Mr. Wallace's opinion on the point in question. For it is +notorious that these co-authors of the theory of natural selection have +expressed divergent opinions concerning the origin by natural selection +of the most general of all specific characters--cross-sterility. +Although allowing that cross-sterility between allied species may be of +adaptive value in "keeping incipient species from blending," Darwin +persistently refused to be influenced by Wallace's belief that it is due +to natural selection; i.e. the belief on which alone can be founded the +"necessary deduction" with which we have been throughout concerned. + + + + +NOTE A TO PAGE 57. + + +I think it is desirable here to adduce one or two concrete illustrations +of these abstract principles, in order to show how, as a matter of fact, +the structure of Weismann's theory is such as to preclude the +possibility of its assumptions being disproved--and this even supposing +that the theory is false. + +At first sight nothing could seem more conclusive on the side of +Darwinian or Lamarckian principles than are the facts of hereditary +disease, in cases where the disease has unquestionably been acquired by +the parents. Take, for example, the case of gout. Here there is no +suspicion of any microbe being concerned, nor is there any question +about the fact of the disease being one which is frequently acquired by +certain habits of life. Now, suppose the case of a man who in middle age +acquires the gout by these habits of life--such as insufficient +exercise, over-sufficient food, and free indulgence in wine. His son +inherits the gouty diathesis, and even though the boy may have the fear +of gout before his eyes, and consequently avoid over-eating and +alcoholic drinking, &c., the disease may overtake him also. Well, the +natural explanation of all this is, that the sins of the fathers descend +upon the children; that gout acquired may become in the next generation +gout transmitted. But, on the other hand, the school of Weismann will +maintain that the reason why the parent contracted the gout was because +he had a congenital, or "blastogenetic," tendency towards that +disease--a tendency which may, indeed, have been intensified by his +habits of life, but which, in so far as thus intensified, was not +transmitted to his offspring. All that was so transmitted was the +congenital tendency; and all that is proved by such cases as those above +supposed, where the offspring of gouty parents become gouty +notwithstanding their abstemious habits, is that in such offspring the +congenital tendency is even more pronounced than it was in their +parents, and therefore did not require so much inducement in the way of +unguarded living to bring it out. Now, here again, without waiting to +consider the relative probabilities of these two opposing explanations, +it is enough for the purposes of the illustration to remark that it is +obviously impossible to disprove either by means of the other, or by any +class of facts to which they may severally appeal. + +I will give only one further example to show the elusiveness of +Weismann's theory, and the consequent impossibility of finding any cases +in nature which will satisfy the conditions of proof which the theory +imposes. In one of his papers Weismann says that if there be any truth +in the Lamarckian doctrine of the transmission of acquired characters, +it ought to follow that the human infant should speak by instinct. For, +ever since man became human he has presumably been a talking animal: at +any rate it is certain that he has been so for an innumerable number of +generations. Therefore, by this time the faculty of language ought to +have been so deeply impressed upon the psychology of the species, that +there ought to be no need to teach the young child its use of language; +and the fact that there is such need is taken by Weismann to constitute +good evidence in proof of the non-transmissibility of individually +acquired characters. Or, to quote his own words, "it has never yet been +found that a child could read of itself, although its parents had +throughout their whole lives practised this art. Not even are our +children able to talk of their own accord; yet not only have their +parents, but, more than that, an infinitely long line of ancestors have +never ceased to drill their brains and to perfect their organs of +speech.... From this alone we may be disposed to doubt whether acquired +capabilities in the true sense can ever be transmitted." Well, in answer +to this particular case, we have first of all to remark that the +construction of even the simplest language is, psychologically +considered, a matter of such enormous complexity, that there is no real +analogy between it and the phenomena of instinct: therefore the fact +that Lamarckian principles cannot be applied to the case of language is +no evidence that they do not hold good as regards instinct. Secondly, +not only the construction, but still more the use of language is quite +out of analogy with all the phenomena of instinct; for, in order to use, +or speak, a language, the mind must already be that of a thinking agent; +and therefore to expect that language should be instinctive is +tantamount to expecting that the thought of which it is the vehicle +should be instinctive--i.e. that human parents should transmit the whole +organization of their own intellectual experiences to their unborn +children. Thirdly, even neglecting these considerations, we have to +remember that language has been itself the product of an immensely long +course of evolution; so that even if it were reasonable to expect that a +child should speak by instinct without instruction, it would be +necessary further to expect that the child should begin by speaking in +some score or two of unknown tongues before it arrived at the one which +alone its parents could understand. Probably these considerations are +enough to show how absurd is the suggestion that Darwinians ought to +expect children to speak by instinct. But, now, although it is for these +reasons preposterous under any theory of evolution to expect that +children should be able to use a fully developed language without +instruction, it is by no means so preposterous to expect that, if all +languages present any one simple set of features in common, these +features might by this time have grown to be instinctive; for these +simple features, being common to all languages, must have been +constantly and forcibly impressed upon the structure of human psychology +throughout an innumerable number of sequent generations. Now, there is +only one set of features common to all languages; and this comprises the +combinations of vowel and consonantal sounds, which go to constitute +what we know as articulate syllables. And, is it not the case that these +particular features, thus common to all languages, as a matter of fact +actually _are_ instinctive? Long before a young child is able to +understand the meanings of any words, it begins to babble articulate +syllables; and I do not know that a more striking fact can be adduced at +the present stage of the Weismann controversy than is this fact which he +has thus himself unconsciously suggested, namely, that the young of the +only talking animal should be alone in presenting--and in unmistakably +presenting--the instinct of articulation. Well, such being the state of +matters as regards this particular case, in the course of a debate which +was held at the Newcastle meeting of the British Association upon the +heredity question, I presented this case as I present it now. And +subsequently I was met, as I expected to be met, by its being said that +after all the faculty of making articulate sounds might have been of +congenital origin. Seeing of how much importance this faculty must +always have been to the human species, it may very well have been a +faculty which early fell under the sway of natural selection, and so it +may have become congenital. Now, be it remembered, I am only adducing +this case in illustration of the elusiveness of Weismann's theory. First +of all he selects the faculty of articulate speech to argue that it is a +faculty which ought to be instinctive if acquired characters ever do +become instinctive; and so good does he deem it as a test case between +the two theories, that he says _from it alone_ we should be prepared to +accept the doctrine that acquired characters can never become +congenital. Then, when it is shown that the only element in articulate +speech which possibly could have become congenital, actually has become +congenital, the answer we receive is a direct contradiction of the +previous argument: the faculty originally selected as representative of +an acquired character is now taken as representative of a congenital +one. By thus playing fast and loose with whatever facts the followers of +Darwin may adduce, the followers of Weismann bring their own position +simply to this:--All characters which can be shown to be inherited we +assume to be congenital, or as we term it, "blastogenetic," while all +characters which can be shown not to be inherited, we assume to be +acquired, or as we term it, "somatogenetic"--and this merely on the +ground that they have been shown to be inherited or not inherited as the +case may be. Now, there need be no objection to such assumptions, +provided they are recognized as assumptions; but so long as the very +question in debate has reference to their validity as assumptions, it is +closely illogical to adduce them as arguments. And this is the only +point with which we are at present concerned. + + + + +NOTE B TO PAGE 89. + + +In answer to this illustration as previously adduced by me, Mr. Poulton +has objected that the benefit arising from the peculiar mode of stinging +in question is a benefit conferred, not on the insect which stings, but +upon its progeny. The point of the illustration however has no reference +to the maternal instinct (which here, as elsewhere, I doubt not is due +to natural selection); it has reference only to the particular instinct +of selective stinging, which here ministers to the purposes of the other +and more general instinct of rearing progeny. Given then the maternal +instinct of stinging prey for the use of progeny, the question is--What +first determined the ancestors of the Sphex to sting their prey only in +nine particular points? Darwin's answer to this question is as +follows:-- + + "I have been thinking about Pompilius and its allies. Please take + the trouble to read on perforation of the corolla by Bees, p. 425 + of my 'Cross-fertilization,' to end of chapter. Bees show so much + intelligence in their acts, that it seems not improbable to me that + the progenitors of Pompilius originally stung caterpillars and + spiders, &c., in any part of their bodies, and then observed by + their intelligence that if they stung them in one particular place, + as between certain segments on the lower side, their prey was at + once paralyzed. It does, not seem to me at all incredible that this + action should then become instinctive, i.e. memory transmitted from + one generation to another. It does not seem necessary to suppose + that when Pompilius stung its prey in the ganglion it intended or + knew that their prey would keep long alive. The development of the + larvae may have been subsequently modified in relation to their + half-dead, instead of wholly dead prey; supposing that the prey was + at first quite killed, which would have required much stinging. + Turn this over in your mind," &c. + +Weismann, on the other hand, can only suppose that this intensely +specialized instinct had its origin in fortuitous variations in the +psychology of the species. But, neglecting the consideration that, in +order to become fixed as an instinct by natural selection, the +particular variation required must have occurred in many different +individuals, not only in the first, but also in the sequent generations, +the chances against its occurring only once, or in but one single +individual case, are many thousands if not millions to one. + + + + +INDEX + + +A. + +Acceleration and retardation, 16. + +Acquired characters, heredity of, 39, 103, 133. + +Adaptation, 7, 13, 55, 62, 67, 71, 159, 165; + of species and of specific characters, 166. + +ALLEN, Mr., referred to, 209. + +_All-sufficiency of Natural Selection_, referred to, 65, 95. + +_Alone with the Hairy Ainu_, referred to, 26. + +American and European trees compared, 201. + +_American Journal of Science_, referred to, 273. + +_American Naturalist_, referred to, 35, 58. + +Ammonites, species of, 254. + +_Animal Intelligence_, referred to, 93. + +_Animal Life_, referred to, 101. + +_Animal Life and Intelligence_, referred to, 33, 36. + +_Apparent Paradox in Mental Evolution_, referred to, 90. + +Appendages of Normandy and Irish pigs, 188. + +Articulation and inheritance, 335. + +Artistic faculties of man, 27. + + +B. + +BABINGTON, Prof., referred to, 252. + +BACHMAN, Dr., referred to, 186. + +BAILEY, Prof., referred to, 127. + +BAKER, Mr., referred to, 252. + +Balancing of brainless frog, 78. + +BALL, Mr. Platt, referred to, 3, 95; quoted, 50. + +BATESON, Mr. W., referred to, 36. + +BEDDARD, Mr. F., referred to, 174. + +BENTHAM, Mr., referred to, 252. + +Birds, diagnostic characters of, 176; + of Australia, effect of climate on, 210; + influence of food on, 218. + +Blastogenetic, 123, 242, 245, 250. + +Blending of adaptations, 67. + +_Brain_, referred to, 80. + +BROCA, Prof., referred to, 64, 67, 174, 318. + +BRONN, Prof., referred to, 174. + +BROOKS, Prof., referred to, 14. + +BROWN-SÉQUARD, referred to, 104, 122, 142; quoted, 104. + +BUCKLEY, Mr., referred to, 147. + +BUCKMAN, Prof. James, referred to, 125. + +BUCKMAN, Prof. S.S., referred to, 24. + +BUTLER, Mr. A. G., referred to, 254. + +BUTLER, Mr. Samuel, referred to, 87. + +Butterfly, seasonal changes of, 210; + influence of food on, 217. + + +C. + +Carnivora, instincts of, 89. + +CARRIÈRE, M. L. A., referred to, 123. + +Cave animals, colour-changes in, 211. + +_Cave Fauna of North America_, quoted, 211. + +Cessation of Selection, 99, 199, 212, 292. + +Characters, adaptive and specific, 159, 307; + specific, due to Natural Selection, 171. + +_Charadriidae, Geographical Distribution of the Family_, quoted, 173. + +Chimpanzee, counting of, 31. + +Climate, influence of, on plants, 200; + on animals, 209. + +Co-adaptation, 64. + +COCKERELL, Prof., referred to, 218. + +Colour, 269. + +Colour-changes in butterflies, 210. + in cave animals, 211. + +_Colours of Animals_, referred to, 36. + +Congenital, as opposed to acquired characters, 134. + +Constancy of characters not necessarily due to Natural Selection, 186. + +_Contemporary Review_, referred to, 60, 65, 95 + +Continuity of germ-plasm, 44, 61, 133; + absolute and relative, 134, 155. + +_Contributions to the Theory of Natural Selection_, referred to, 2; +quoted, 180. + +COPE, Prof., referred to, 14, 15, 20, 63, 256; quoted, 16. + +Correlation, 171, 184, 211, 222, 268. + +COSTA, M., quoted, 217. + +CUNNINGHAM, Mr. J. T., quoted, 103; referred to, 95, 122. + + +D. + +DALL, Prof., referred to, 14. + +DARWIN, Charles, referred to, 1-13, 20-22, 25, 44, 45, 51-53, 56, 66, +67, 74, 87, 88, 93, 95, 96-100, 149, 159, 160, 167, 173, 174, 181-183, +187-191, 193, 195, 198, 200-202, 213-216, 218, 219, 226, 256, 261-265, +268, 271, 277, 283, 287, 291, 305-307, 313-332, 337; quoted, 11, 53, 66, +96, 181, 182, 186-191, 193, 195, 201, 202, 213-215, 261, 262, 265, +313-316, 319-322, 324-326, 328-331, 337. + +_Darwin et ses Précurseurs Français_, referred to, 234. + +_Darwinian Theory of the Origin of Species_, quoted, 254. + +_Darwinism_, quoted, 22, 27, 67, 181, 182, 186, 189-191, 221, 222, 235, +236, 252, 253, 269, 270, 273, 313, 316; referred to, 7, 12, 15, 20, 70. + +DE CANDOLLE, Prof., referred to, 206. + +Deep-sea faunas, 212. + +DELB[OE]UF, referred to, 224. + +_Descent of Man_, quoted, 25, 322-324, 331. + +_Development of the Hard Parts of the Mammalia_, referred to, 14. + +DE VRIES, Prof., referred to, 122, 174. + +Diagnostic characters of birds, 176; + Marsupials, 178. + +Divergent Evolution through Cumulative Segregation, quoted, 224. + +DIXON, Mr. Charles, referred to, 174; quoted, 177, 223. + +_Doctrine of Descent and Darwinism_, quoted, 260. + +Dogs, scratching, reflex of, 80; + shaking off water, 84; + transplantation of ovaries, 143. + +DORFMEISTER, Dr., referred to, 211. + +Ducks, use-inheritance in, 96; + losing true plumage, 187. + +DUPUY, Dr., referred to, 105. + +DYER, Mr. Thistleton, quoted, 325, 327. + + +E. + +_Effect of External Influences upon Development_, referred to, 66, 95. + +_Effects of Use and Disuse_, quoted, 50. + +EIMER, Prof., referred to, 14, 174, 217. + +_Entomological Society, Trans. of_, quoted, 211; referred to, 217. + +Epilepsy of guinea-pigs, 104. + +_Essays on Heredity_, quoted, 56, 91, 97, 107, 152; referred to, 12, 36, +65, 105, 110. + +EUDES-DESLONGCHAMPS, M., referred to, 188. + +European and American trees, compared, 201. + +EVEREST, Rev. E., quoted, 213. + +_Evolution without Natural Selection_, quoted, 177. + +_Examination of Weismannism_, referred to, 39-42, 44, 100, 122, 123, +134, 136, 138-140, 156. + +_Experiments in Pangenesis_, referred to, 145. + + +F. + +FABRE, M., referred to, 88. + +Factors of organic evolution: + Natural Selection, 2, 5, 6; + use-inheritance, 3, 11. + +_Factors of Organic Evolution_, referred to, 8. + +Faculties and organs, 29. + +Fertility, 229. + +Flat-fish, Mr. Cunningham on, 103. + +_Floral Structures_, referred to, 19. + +FOCKE, Dr., referred to, 174. + +_Fonctions du Cerveau_, referred to, 109. + +Food, influence of, 217. + +Foot, of man, 23. + +Frog, brainless, balancing of, 78. + + +G. + +GALTON, Mr. Francis, referred to, 40-48, 100, 103, 134-139, 145, 146, +152, 154, 156, 300, 303-305; quoted, 46, 100. + +Gangrene, effects of, 54, 105. + +_Gardener's Chronicle_, quoted, 127. + +GÄRTNER, Dr., referred to, 206. + +GEDDES, Prof., referred to, 15, 20,174. + +Gemmules, 47, 145, 155. + +Genera and species, 261. + +Germ-plasm and Stirp, 40; + and pangenesis, 42; + isolation of, 137; + stability of, 243. + +_Germ-plasm_, referred to, 128. + +GIARD, Prof., referred to, 14, 174. + +Giraffe, co-adaptation in, 64. + +GOLTZ, Prof., referred to, 80, 84. + +GOULD, Mr., referred to, 210. + +Graft-hybridization, 143. + +Growth, laws of, 222, 226, 248, 270, 321. + +Guinea-pigs, epilepsy of, 104. + +GULICK, Mr., referred to, 174, 259, 260, 271; quoted, 224, 273. + +_Gute und schlechte Arten_, quoted, 203. + + +H. + +Habit, hereditary, 87. + +_Habit and Intelligence_, quoted, 225. + +Hand, of man, 24. + +_Handbook of British Flora_, referred to, 252. + +HAYCRAFT, Prof., referred to, 80. + +HEAPE, Mr. Walter, referred to, 147. + +HENSLOW, Prof. George, referred to, 18-20, 127-132, 174, 208; quoted, +19, 130, 131. + +Heredity, problems of, 39. + +HERING, Prof., referred to, 87. + +HEWITT, Mr., referred to, 187. + +HILL, Prof. Leonard, quoted, 132. + +HAECKEL, Prof., referred to, 174, 260, 282. + +HOFFMANN, Dr., referred to, 123, 280. + +Horse, callosities of, 265. + +HUXLEY, Prof. T. H., referred to, 167-170, 185, 256, 275, 283, 307-312; +quoted, 307-309. + +Huxleyan doctrine of species, 167. + +_Hyatt_, Prof., referred to, 14, 15. + +Hymenoptera, social, 92. + + +I. + +_Inadequacy of Natural Selection_, referred to, 65, 95. + +_Inconsistencies of Utilitarianism as the Exclusive Theory of Organic +Evolution_, quoted, 273. + +Indifferent characters, 171, 185, 208, 247. + +Insects, instincts of, 91. + +Instability of useless characters, 186. + +Instinct and hereditary habit, 87; + of Sphex, 88; + of carnivora, 89; + of man, 89; + Prof. Weismann's views on, 90; + of insects, 91. + +Intercrossing, 67-71. + +Isolation, 223 _et seq._ + + +J. + +JORDAN, Dr., referred to, 206, 252. + + +K. + +Karyokinesis, 140. + +KERNER, Prof., referred to, 174, 202-206, 231, 239, 260, 282; quoted, +203. + +KOCH, Dr., referred to, 217. + +KÖLLIKER, Prof., referred to, 174. + + +L. + +Lamarck, referred to, 9-15. + +Lamarckism, 9, 61, 113. + +LANDOR, A. H. Savage, referred to, 26. + +Language and Weismannism, 334. + +LANKESTER, Prof. Ray, quoted, 245, 299; referred to, 305. + +LESAGE, M., referred to, 126. + +_Life and Letters of Charles Darwin_, quoted, 319, 320; referred to, 11. + +LUCIANI, referred to, 109. + + +M. + +_Making of Flowers_, referred to, 19. + +_Manual of British Botany_, referred to, 252. + +_Manual of Dental Anatomy_, figure from, 267. + +Marsupials, diagnostic characters of, 178. + +_Materials for the Study of Variation_, referred to, 36. + +MEEHAN, Mr., referred to, 201. + +MELDOLA, Prof., referred to, 68. + +_Mental Evolution in Animals_, referred to, 25, 88, 89, 92. + +_Mental Evolution in Man_, referred to, 31. + +MERRIFIELD, Mr., referred to, 211. + +Mice, mutilation of tails of, 148. + +MIVART, Prof. St. George, referred to, 4, 174, 217. + +Monstrosity, in turkeys, 181; + in cattle, 196. + +MORGAN, Prof. Lloyd, referred to, 33, 36, 174, 271, 300-305; quoted, +300, 303. + +MOSELEY, Prof., referred to, 26. + +MURPHY, Mr. J. J., referred to, 224. + +Mutilations, inheritance of, 53, 148. + + +N. + +NÄGELI, Prof., referred to, 174, 206, 318. + +Naked skin of man, 25. + +NATHUSIUS, referred to, 188. + +Natural Selection, range of, 2, 5, 51, 62, 92; + a theory of species, 161, 169; + and cave animals, 211; + and Porto Santo rabbits, 214. + +_Natural Selection and Tropical Nature_, quoted, 23. + +_Natural Science_, quoted, 104. + +_Nature_, quoted, 132, 223, 245, 299, 325; referred to, 68, 98, 218. + +Neo-Darwinian school, 10, 61. + +Neo-Lamarckian school, 13, 62, 63. + +_Neuer Beitrag zum geologischen Beweis der Darwin'schen Theorie_, +quoted, 254. + +_Neuter Insects and Darwinism_, referred to, 95. + +_Neuter Insects and Lamarckism_, referred to, 95. + +Neuters of hymenopterous insects, 92. + +NEWMAN, Cardinal, referred to, 20. + +Niata cattle, 191. + + +O. + +OBERSTEINER, Dr., referred to, 105, 106. + +_Oesterreichische medicinische Jahrbücher_, referred to, 105. + +_On Truth_, referred to, 217. + +Orang-utan, teeth of, 267. + +_Organic Evolution_, referred to, 217. + +_Origin of the Fittest_, quoted, 16; referred to, 14. + +_Origine des Plantes Domestiques, démontrée par la culture du Radis +sauvage_, referred to, 123. + +_Origin of Sex_, referred to, 17. + +_Origin of Species_, quoted, 3, 4, 181, 182, 186, 188, 190, 261, 262, +265, 321, 322, 325, 326, 329; referred to, 67, 159, 227, 286. + +OSBORN, Prof., referred to, 14, 58, 63. + +OWEN, Sir Richard, referred to, 191. + +Oxen, skulls of, compared, 192. + +Oysters, change of, 217. + + +P. + +PACKARD, Prof., referred to, 14, 213. + +Pangenesis, 11, 42. + +Panmixia, 97, 212, 291. + +Parsimony, law of, 51. + +Parsnips, variation of, 125. + +PASCOE, Mr., referred to, 174; quoted, 254. + +PERRIER, Prof., referred to, 14, 93, 95. + +PETER, Dr., referred to, 206. + +PFEFFER, Herr, referred to, 15. + +_Pflüger's Archiv_, referred to, 80. + +_Philosophical Transactions_, referred 10, 103. + +_Physiological Selection_, referred to, 187, 307, 313, 324; quoted, 188, +308. + +_Pickard-Cambridge_, Rev. O., quoted, 221. + +Pig, old Irish, 188. + +Plants, influence of climate on, 122-207. + +Porto Santo rabbits, 214. + +POULTON, E. B., referred to, 36, 217, 337. + +_Presidential Address to the Bristol Naturalists Society_, 1891; quoted, +300, 303. + +_Proceedings of the Royal Society_, referred to, 145, 147; quoted, 307. + +Protective resemblance, 72. + +Protrusion of eyeball, in epileptic guinea-pigs, 111. + + +Q. + +QUATREFAGES, M., referred to, 234. + + +R. + +Rabbits, and use-inheritance, 96; + transplantation of ovaries, 143; + Porto Santo, 214. + +Radish, variation of, 123. + +Rats, scratching, reflex of, 81. + +_Raupen und Schmetterlinge der Wetterau_, referred to, 217. + +Reflex action and use-inheritance, 64-87. + +_Rejoinder to Prof. Weismann_, referred to, 95. + +Reversal of selection, 101, 292. + +_Revue Générale de Botanie_, referred to, 126. + +RICHARDSON, referred to, 188. + +ROUX, Prof., referred to, 298. + +Rudiments, 294. + +RYDER, Prof., referred to, 14. + + +S. + +SACHS, Prof., referred to, 15, 174. + +"Sally," counting of, 31. + +SAUERMANN, Dr., referred to, 218. + +SCHÄFER, Prof., referred to, 145. + +_Schmetterlinge des Südwestlichen Deutschlands_, referred to, 217. + +SCHMIDT, Dr. Oscar, quoted, 260. + +Schools of Evolutionists, 12-20. + +SCOTT, Prof., referred to, 63. + +Scratching, reflex, in dogs, 80; + in rats, 81. + +Seasonal changes of butterflies, 210. + +SEEBOHM, Mr. Henry, quoted, 173; referred to, 174. + +Selection, cessation of, 99, 292; + reversal of, 101, 292. + +Selection, sexual, 219 _et seq._ + +Selective value, 73. + +Self-adaptation, 18. + +SEMPER, Prof. Karl, referred to, 101. + +Sexual selection, 219 _et seq._ + +Sole, pigment of, 104. + +Somatogenetic and somatoplasm, 123, 137, 155, 242-249. + +_Some Laws of Heredity_, referred to, 24. + +Species, stress laid on origin of, 159; + necessarily due to natural selection, 168. + +---- definitions of, 229. + +SPENCER, Herbert, referred to, 8, 64-68, 95. + +Sphex, instincts of, 88, 337. + +STEBBING, Rev. T. R., quoted, 25. + +Sterility, 8. + +Stirp and germ-plasm, 40, 47, 138. + +_Struggle for Existence between the parts of an Organism_, referred to, +299. + + +T. + +Theory of Heredity, referred to, 40, 47, 137, 154; quoted, 46, 47. + +THOMAS, Mr. Oldfield, referred to, 178. + +THOMSON, J. A., referred to, 15. + +TODD, J. E., referred to, 35. + +TOMES, Mr., referred to, 267. + +Transfusion of blood in rabbits, 145. + +Transplantation of ovaries in rabbits, 143, 147. + +Trees, comparison of European and American, 201. + +Turkey, tuft of hair of, 181; + losing metallic tints, 186. + + +U. + +Use-inheritance, 3, 49, 77, 95, 151. + +Utility, law of, 8, 20, 159; + universality of, 166; + of specific characters, 172; + of specific characters in birds, 176; + of specific characters in Mammals, 178. + + +V. + +_Variation of Animals and Plants under Domestication_, quoted, 3, 4, 53, +66, 96, 187, 189, 191, 193, 195, 213-216, 330, 331. + +Varieties, climatic, 228. + +Vestigial characters, 171, 184, 261, 294. + +VINES, Prof., referred to, 297. + +Vitality, plumes of birds due to surplus, 270, 25. + +Voice, of man, 25. + + +W. + +WAGNER, Moritz, referred to, 217. + +WALLACE, Mr. A. R., referred to, 2, 6, 9, 11, 15, 20-35, 50, 66-70, 167, +169, 172-175, 180-198, 210, 218-227, 235-237, 252, 256, 258, 263-278, +285, 313-322, 328, 331, 332; quoted, 22-24, 27, 67, 180-182, 185, 186, +190, 191, 221-223, 235, 236, 269, 273, 313. + +Wallacean doctrine of species, 167, 169. + +WEISMANN, Prof., referred to, 2, 7, 9, 12, 13, 39-60, 65, 66, 90-105, +112, 128, 134-142, 148, 149, 151, 152, 155, 156, 173, 241, 243, 244, +246, 279, 280, 291, 294, 297, 298, 300, 311, 338; quoted, 56, 91, 97, +152, 243, 244, 297. + +Weismannism, diagram of constituent theories, 43, 136; + elusiveness of, 334. + +_Weismannism once more_, referred to, 66, 95. + +WELBY, Hon. Lady, referred to, 90. + +WESTPHAL, Prof., referred to, 105, 107. + +Withdrawal of foot by reflex action, 75. + +WÜRTENBERGER, Dr., referred to, 254. + + +Y. + +YARRELL, Mr., referred to, 186. + + + + +LIST OF OPEN COURT PUBLICATIONS ON SCIENCE + + +The Primary Factors of Organic Evolution. By E. D. Cope. Second +edition. Pages, 550; illustrations, 121; tables, bibliography, and +index. Cloth, $2.00 net. + + A comprehensive handbook of the Neo-Lamarckian theory of Evolution. + + +A Mechanico-Physiological Theory of Organic Evolution. By Carl von +Naegeli. Translated by V. A. Clark and F. A. Waugh. Price, cloth, 60c; +paper, 30c net. + + A synopsis of his great work on evolution. + + +Darwin and After Darwin. An exposition of the Darwinian Theory and a +Discussion of Post-Darwinian Questions. By George J. Romanes. 3 vols. +Price, $4.00 net. + +Part I. The Darwinian Theory. Price, cloth, $2.00 net. + +Part II. Post-Darwinian Questions: Heredity and Utility. Price, cloth, +$1.50 net. + +Part III. Post-Darwinian Questions. Isolation and Physiological +Selection. Price, cloth, $1.00 net. + + +An Examination of Weismannism. By George J. Romanes. Price, cloth, +$1.00 net; paper, 40c net. + + "The best criticism of the subject in our language."--_The + Outlook._ + + +On Germinal Selection. By August Weismann. Translated by T. J. +McCormack. Price, paper, 30c net. + + +The Rise of Man. A Sketch of the Origin of the Human Race. By Paul +Carus. Pages, 97; illustrated. Boards, cloth back, 75c net. + + +The Scope and Content of the Science of Anthropology. By Juul +Dieserud. Pages, 200; cloth, gilt top, $2.00 net. + + "The science of Anthropology," according to Topinard, "is that + branch of natural history which treats of man, and the races of + men." + + +Experiments on the Generation of Insects. By Francesco Redi. +Translated from the Italian edition of 1688, by Mab Bigelow. +Illustrated. Cloth, $2.00 net. + + This book may be counted as one of the classics of the theory of + evolution. + + +Ants and Some Other Insects. An Inquiry into the Psychic Powers of +these Animals, with an Appendix on the peculiarities of their Olfactory +Sense. By August Forel. Translated by William M. Wheeler. Price, +$1.00 net; paper, 55c net. + + +Plant Breeding. Comments on the Experiments of Nilsson and Burbank. By +Hugo de Vries. Pages, xv, 360. Illustrated with 114 half-tone plates +from nature. Printed on fine paper, in large type. Cloth, gilt top. +Price, $1.50 net. + + A scientific book in simple language. Intensely interesting as well + as instructive. Of special value to every botanist, horticulturist + and farmer. + + +Species and Varieties, Their Origin by Mutation. Lectures delivered at +the University of California by Hugo de Vries, Professor of Botany in +the University of Amsterdam. Pages, xviii, 847. Cloth, gilt top, $5.00 +net. + + +The Mutation Theory. Experiments and Observations on the Origin of +Species in the Vegetable Kingdom. 2 vols. Numerous illustrations, +colored plates. By Hugo de Vries. Translated by Prof. A. B. Farmer +and A. D. Darbishire. Cloth, per volume, $4.00. + + This is de Vries' great book on a new explanation of the evolution + theory, accounting for the formation of species not by the struggle + for existence but by mutation. + + +Intracellular Pangenesis. Including a paper on Fertilization and +Hybridization. By Hugo de Vries. Translated from the German by C. +Stuart Gager. Cloth, $3.00 net. + + This is de Vries' first important book. It is not very large, but + ought to be read by all students of botany, and also by those who + are interested in the theory of evolution. + + +On Orthogenesis and the Impotence of Natural Selection in +Species-Formation. By Th. Eimer. Translated by T. J. McCormack. +Price, paper, 30c net. + + Another critic of Darwin who claims that organisms develop through + transmission of acquired characters. + + +On the Inheritance of Acquired Characters. By Eugenio Rignano. +Translated by Basil C. H. Harvey. With an Appendix "On the Mnemonic +Origin and Nature of Affective Tendencies." Cloth, $3.00 net. + + Rignano calls his theory "centro-epigenesis" and is greatly + influenced by Weismann. + + +On Double Consciousness. Studies in Experimental Psychology. By +Alfred Binet. Third edition. Pages, 93. Cloth, 50c net; paper, 20c +net. + + "A most valuable contribution to this important subject which none + of its students can afford to leave unread."--_Public Opinion._ + + +The Psychic Life of Micro-Organisms. By Alfred Binet. Authorized +translation. Pages, xii, 120. Cloth, 75c net; paper, 30c net. + + "He fortifies his theory by such a wealth of exact observation and + experiments that the reader who follows his demonstration carefully + can hardly fail of conviction."--_New York Tribune._ + + +The Psychology of Reasoning. By Alfred Binet. Translated from the +second French edition by Adam Gowans Whyte, B.Sc. Pages, 191. Cloth, +75c net; paper, 30c net. + + "Like everything that Dr. Binet writes, the subject is stated and + expounded lucidly."--_The Lancet._ + + +The Diseases of Personality. By Théodule Ribot. Authorized +translation. Fourth edition. Pages, 157. Cloth, 75c net; paper, 30c. + + Contents: Introduction, Consciousness; Organic Disorders; Affective + Disorders; Diseases of the Intellect; Dissolution of Personality. + + +The Diseases of the Will. By Théodule Ribot. Authorized translation. +Third edition. Pages, vi, 121. Cloth, 75c net; paper, 30c net. + + Contains chapters on impairments of the will and of voluntary + attention, the realm of caprices, and extinction of the will. + + +Essay on the Creative Imagination. By Théodule Ribot. Translated +from the French by A. H. N. Baron, Fellow in Clark University. Cloth, +gilt top. Pages, 357. $1.75 net. + + The motor nature of the constructive imagination. + + +The Psychology of Attention. By Théodule Ribot, Professor in the +Collège de France and editor of the "Revue Philosophique." Fifth and +revised edition. Authorized translation. Pages, 121. Cloth, 75c net; +paper, 30c net. + + Contents: Spontaneous or Natural Attention; Voluntary or Artificial + Attention; Morbid States of Attention. + + +The Diseases of Memory. By Théodule Ribot. Cloth, $1.50 net. + + +Memory. Lectures on the Specific Energies of the Nervous System. By +Ewald Hering. Fourth edition, containing an additional chapter on the +Theory of Nerve Activity. Cloth, $1.00 net. + + +The Analysis of Sensations and the Relation of the Physical to the +Psychical. By Ernst Mach, Emeritus Professor in the University of +Vienna. Translated by C. M. Williams. Third edition revised and +supplemented from the fifth German edition by Sydney Waterlow, M.A. +Pages, xvi, 380. Cuts, 37. Cloth, $1.50 net. + + +Popular Science Lectures. By Ernst Mach, Professor in the University +of Vienna. Translated from the German by T. J. McCormack. Third +edition. Pages, 415. Cloth, gilt top, $1.50 net; paper, 60c net. + + A portrayal of the methods and spirit of science, in lectures on + mechanics, sound, light, electricity, the conservation of energy, + philosophy and education. + + +Man a Machine. By Julien Offray De La Mettrie. Including Frederick +the Great's Eulogy on La Mettrie and Extracts from La Mettrie's "Natural +History of the Soul." Translated, with notes, by Gertrude Carman +Bussey. French-English edition. With a portrait of La Mettrie. Pages, +226. Cloth, $2.00 net. + + La Mettrie was the most extreme writer among the earliest French + materialists. His doctrine is an extension to man of Descartes' + doctrine that animals are automata. + + + + +PORTRAITS + +Philosophical and Psychological Portrait Series + + +Printed on large paper (11 × 14) with tint and platemark. Many of them +are reproduced from rare paintings, engravings, or original photographs. +They are suitable for framing and hanging in public and private +libraries, laboratories, seminaries, recitation and lecture rooms, and +will be of interest to all concerned in education and general culture. + + +PHILOSOPHICAL + +Pythagoras +Socrates +Plato +Aristotle +Epictetus +Thomas Aquinas +St. Augustine +Averrhoes +Duns Scotus +Giordano Bruno +Bacon +Hobbes +Descartes +Malebranche +Herbert Spencer +Schelling +Spinoza +Locke +Berkeley +Hume +Montesquieu +Voltaire +D'Alembert +Condillac +Diderot +Rousseau +Leibniz +Wolff +Kant +Fichte +Hegel +Schleiermacher +Schopenhauer +Herbart +Feuerbach +Lotze +Reid +Dugald Stewart +Sir W. Hamilton +Cousin +Comte +Rosmini +J. Stuart Mill + + +PSYCHOLOGICAL + +Cabanis +Maine de Biran +Beneke +E. H. Weber +Fechner +Helmholtz +Wundt +Hering +G. T. Ladd +Aubert +Mach +Stumpf +Exner +Steinthal +Bain +Sully +Ward +C. L. Morgan +Romanes +Paul Janet +Ribot +Taine +Fouillée +Binet +G. Stanley Hall + + +PRICES: + +Philosophical and Psychological Portrait Series. + + 68 portraits on plate paper, $7.50 per set net. On Japanese vellum, + $12.50 per set net. + +Philosophical Portrait Series. + + No. 100. 43 portraits on plate paper, $6.25 per set net. + + No. 100a. 43 portraits on Japanese vellum, $8.75 per set net. + + Single portraits on American plate, 25c net. + + Single portraits on Japanese vellum, 35c net. + + +Psychological Portrait Series. + + No. 101. 25 portraits on plate paper, $3.75 net. + + No. 101a. 25 portraits on Japanese vellum, $5.00 net. + + Single portraits on American plate, 25c net. + + Single portraits on Japanese vellum, 35c net. + + +Framing Portrait of Hugo de Vries. + + Platino finish. 10" × 12", unmounted, $1.00 net. + + +Framing Portrait of William James. + + Printed on Japan paper. 11" × 14", $1.00. + + +Portraits of Eminent Mathematicians + +Three portfolios edited by David Eugene Smith, Professor of Mathematics +in Teachers' College, Columbia University, New York. + +In response to a widespread demand from those interested in mathematics +and the history of education, Professor Smith has edited three +portfolios of the portraits of some of the most eminent of the world's +contributors to the mathematical sciences. Accompanying each portrait is +a brief biographical sketch, with occasional notes of interest +concerning the artist represented. The pictures are of a size that +allows for framing (11" × 14"), it being the hope that a new interest in +mathematics may be aroused through the decoration of classrooms by the +portraits of those who helped to create the science. + +Portfolio No. 1.--Twelve great mathematicians down to 1700 A.D.: Thales, +Pythagorus, Euclid, Archimedes, Leonardo of Pisa, Cardan, Vieta, Napier, +Descartes, Fermat, Newton, Leibniz. + +Portfolio No. 2.--The most eminent founders and promotors of the +infinitesimal calculus: Cavallieri, Johann and Jakob Bernoulli, Pascal, +L'Hopital, Barrow, Laplace, Lagrange, Euler, Gauss, Monge, and Niccolo +Tartaglia. + +Portfolio No. 3--Eight portraits selected from the two former +portfolios, especially adapted for high schools and academies, +comprising portraits of + + Thales--with whom began the study of scientific geometry; + + Pythagoras--who proved the proposition of the square on the + hypotenuse; + + Euclid--whose Elements of Geometry form the basis of all modern + text-books; + + Archimedes--whose treatment of the circle, cone, cylinder and sphere + influences our work today; + + Descartes--to whom we are indebted for the graphic algebra in our + high schools; + + Newton--who generalized the binomial theorem and invented the + calculus; + + Napier--who invented logarithms and contributed to trigonometry; + + Pascal--who discovered the "Mystic Hexagram" at the age of sixteen. + + +Portraits of Mathematicians, Part I. + + No. 102. 12 portraits on American plate paper, $3.00 net. + + No. 102a. 12 portraits on Japanese vellum, $5.00 net. + + Single portraits, American plate, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +Portraits of Mathematicians, Part II. + + No. 103. 12 portraits on American plate paper, $3.00 net. + + No. 103a. 12 portraits on Japanese vellum, $5.00 net. + + Single portraits, American plate paper, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +Portraits of Mathematicians, High School Portfolio. + + Eight portraits selected from the two preceding portfolios. + + No. 104. 8 portraits on American plate paper, $2.00 net. + + No. 104a. 8 portraits on Japanese vellum, $3.50 net. + + Single portraits, American plate paper, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +_For Purchasers who may prefer not to frame the Portraits, a neat +Portfolio can be supplied at an extra cost of $1.00._ + + + + + * * * * * + + + + +Transcriber's note: + + +The following typographical errors were correctred. + + |Page |Error |Correction | + |10 |dicussion |discussion | + |45 |thoughout |throughout | + |229 |pyschological |psychological | + +The following inconsistent hyphenations were changed. + + |Page |Original |Changed to | + |34 |inter-crossing |intercrossing | + |46 |re-appear |reappear | + |123 |re-act |react | + |132 |eye-lid |eyelid | + |216 |lifetimes |life-times | + |217 |lifetime |life-time | + |317 |threefold |three-fold | + +The following inconsistent hyphenations were not changed. + + "somatoplasm" (3 instances) and "somato-plasm" (2 instances) + "twofold" (2) and "two-fold" (1) + "interaction" (1) and "inter-action" (1) + "supernatural" (1) and "super-natural" (1) + +Other changes: + + Page 16 Footnote 10 - double quotes around "acceleration" and + "retardation" changed to single quotes. A double quote inserted at + the end. + + In the Index - Entries "On Truth" and "Orang-utan, teeth of" moved + from under "M" to under "O". + + + +***END OF THE PROJECT GUTENBERG EBOOK DARWIN, AND AFTER DARWIN, VOLUME II +(OF 3)*** + + +******* This file should be named 37759-8.txt or 37759-8.zip ******* + + +This and all associated files of various formats will be found in: +http://www.gutenberg.org/dirs/3/7/7/5/37759 + + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://www.gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS', WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.gutenberg.org/fundraising/pglaf. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://www.gutenberg.org/about/contact + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://www.gutenberg.org/fundraising/donate + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: +http://www.gutenberg.org/fundraising/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. + diff --git a/37759-8.zip b/37759-8.zip Binary files differnew file mode 100644 index 0000000..a0d8507 --- /dev/null +++ b/37759-8.zip diff --git a/37759-h.zip b/37759-h.zip Binary files differnew file mode 100644 index 0000000..d3485ad --- /dev/null +++ b/37759-h.zip diff --git a/37759-h/37759-h.htm b/37759-h/37759-h.htm new file mode 100644 index 0000000..343b7f8 --- /dev/null +++ b/37759-h/37759-h.htm @@ -0,0 +1,13856 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /> +<title>The Project Gutenberg eBook of Darwin, and After Darwin, Volume II (of 3), by George John Romanes</title> + <style type="text/css"> + +body { + margin-left: 10%; + margin-right: 10%; +} + + h1,h2,h3,h4,h5 { + text-align: center; /* all headings centered */ + clear: both; +} + +p { + margin-top: .75em; + text-align: justify; + margin-bottom: .75em; +} + +hr { + width: 33%; + margin-top: 2em; + margin-bottom: 2em; + margin-left: auto; + margin-right: auto; + clear: both; +} + +hr.tb {width: 45%;} +hr.chap {width: 65%} +hr.full {width: 95%;} + +hr.r5 {width: 5%; margin-top: 1em; margin-bottom: 1em;} + +ul.index { list-style-type: none; } +li.ifrst { margin-top: 1em; } +li.indx { margin-top: .5em; } +li.isub1 {text-indent: 1em;} + +table { + margin-left: auto; + margin-right: auto; +} + +.toc5 {margin-left:5%;} + +.toc10 {margin-left:10%;} + +span.ralign { position: absolute; right: 15%; top: auto;} + +.pagenum { /* uncomment the next line for invisible page numbers */ + /* visibility: hidden; */ + position: absolute; + left: 92%; + font-size: smaller; + text-align: right; +} /* page numbers */ + +.center {text-align: center;} + +.smcap {font-variant: small-caps;} + +.caption {font-weight: bold;} + +/* Images */ +.figcenter { + margin: auto; + text-align: center; +} + + +/* Footnotes */ +.footnote {margin-left: 10%; margin-right: 10%; font-size: 0.9em;} + +.footnote .label {position: absolute; right: 84%; text-align: right;} + +.fnanchor { + vertical-align: super; + font-size: .8em; + text-decoration: + none; +} + +span.correction {border-bottom: thin dotted gray;} + +/* Transcriber's notes */ +.transnote {background-color: #E6E6FA; + color: black; + font-size:smaller; + padding:0.5em; + margin-bottom:5em; + font-family:sans-serif, serif; } + + hr.pg { width: 100%; + margin-top: 3em; + margin-bottom: 0em; + margin-left: auto; + margin-right: auto; + height: 4px; + border-width: 4px 0 0 0; /* remove all borders except the top one */ + border-style: solid; + border-color: #000000; + clear: both; } + pre {font-size: 85%;} + </style> +</head> +<body> +<h1>The Project Gutenberg eBook, Darwin, and After Darwin, Volume II (of 3), +by George John Romanes</h1> +<pre> +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at <a href = "http://www.gutenberg.org">www.gutenberg.org</a></pre> +<p>Title: Darwin, and After Darwin, Volume II (of 3)</p> +<p> Post-Darwinian Questions: Heredity and Utility</p> +<p>Author: George John Romanes</p> +<p>Release Date: October 15, 2011 [eBook #37759]</p> +<p>Language: English</p> +<p>Character set encoding: ISO-8859-1</p> +<p>***START OF THE PROJECT GUTENBERG EBOOK DARWIN, AND AFTER DARWIN, VOLUME II (OF 3)***</p> +<p> </p> +<h3>E-text prepared by<br /> + Marilynda Fraser-Cunliffe, L. N. Yaddanapudi,<br /> + and the Online Distributed Proofreading Team<br /> + (http://www.pgdp.net)</h3> +<p> </p> +<hr class="pg" /> +<p> </p> +<p> </p> +<p> </p> + +<h1>DARWIN, AND AFTER DARWIN</h1> + +<h2>II<br /> + +POST-DARWINIAN QUESTIONS<br /> + +HEREDITY AND UTILITY</h2> + + + + +<hr class="r5" /> +<h3>BY THE SAME AUTHOR.</h3> + + +<blockquote><p>DARWIN AND AFTER DARWIN. An Exposition of the +Darwinian Theory and a Discussion of Post-Darwinian +Questions.</p> + +<blockquote><p>1. <span class="smcap">The Darwinian Theory.</span> 460 pages. 125 illustrations. +Cloth, $2.00.</p> + +<p>2. <span class="smcap">Post-Darwinian Questions.</span> Edited by Prof. C. +Lloyd Morgan. 338 pages. Cloth, $1.50. +Both volumes together, $3.00 net.</p></blockquote> + +<p>AN EXAMINATION OF WEISMANNISM. 236 pages. Cloth, +$1.00.</p> + +<p>THOUGHTS ON RELIGION. Edited by Charles Gore, M.A., +Canon of Westminster. Second Edition. 184 pages. Cloth, +gilt top, $1.25.</p></blockquote> + +<p class="center">THE OPEN COURT PUBLISHING COMPANY,<br /> +<span class="smcap">324 Dearborn Street, Chicago</span>.</p> + +<hr class="r5" /> + +<div class="figcenter" style="width: 375px;"> +<img src="images/illus_002.jpg" width="375" height="600" alt="Frontispiece" title="Frontispiece" /></div> + + + + +<hr class="full" /> + +<h1>DARWIN, AND AFTER DARWIN</h1> + +<h2><i>AN EXPOSITION OF THE DARWINIAN THEORY<br /> +AND A DISCUSSION OF<br /> +POST-DARWINIAN QUESTIONS</i></h2> + +<h3><span style="font-size:small;">BY THE LATE</span><br /> +GEORGE JOHN ROMANES, M.A., LL.D., F.R.S.<br /> +<span style="font-size:small;"><i>Honorary Fellow of Gonville and Caius College, Cambridge</i></span></h3> + +<h3>II<br /> +POST-DARWINIAN QUESTIONS<br /> +HEREDITY AND UTILITY</h3> + +<h4><i>FOURTH EDITION</i></h4> +<p> </p> +<p> </p> +<p> </p> + +<h4>Chicago London<br /> +THE OPEN COURT PUBLISHING COMPANY<br /> +1916</h4> + + + + +<hr class="r5" /> +<p class="center smcap">CHAPTER 1 COPYRIGHTED BY<br /> +The Open Court Publishing Co.<br /> +Chicago, Ill., 1895</p> + +<hr class="r5" /> +<p class="center">PRINTED IN THE<br /> +UNITED STATES OF AMERICA</p> + +<hr class="full" /> + +<p class="pagenum"><a name="Page_v" id="Page_v">[Pg v]</a></p> + + + + +<h2>PREFACE</h2> + + +<p>As its sub-title announces, the present volume is +mainly devoted to a consideration of those Post-Darwinian +Theories which involve fundamental +questions of Heredity and Utility.</p> + +<p>As regards Heredity, I have restricted the discussion +almost exclusively to Professor Weismann's views, +partly because he is at present by far the most important +writer upon this subject, and partly because +his views with regard to it raise with most distinctness +the issue which lies at the base of all Post-Darwinian +speculation touching this subject—the issue as to the +inheritance or non-inheritance of acquired characters.</p> + +<p>My examination of the Utility question may well +seem to the general reader needlessly elaborate; for +to such a reader it can scarcely fail to appear that +the doctrine which I am assailing has been broken +to fragments long before the criticism has drawn to +a close. But from my previous experience of the +hardness with which this fallacious doctrine dies, +I do not deem it safe to allow even one fragment of +it to remain, lest, hydra-like, it should re-develop into<span class="pagenum"><a name="Page_vi" id="Page_vi">[Pg vi]</a></span> +its former proportions. And I can scarcely think +that naturalists who know the growing prevalence +of the doctrine, and who may have followed the issues +of previous discussions with regard to it, will accuse +me of being more over-zealous in my attempt to make +a full end thereof.</p> + +<p>One more remark. It is a misfortune attending +the aim and scope of Part II that they bring me +into frequent discord with one or other of the most +eminent of Post-Darwinian writers—especially with +Mr. Wallace. But such is the case only because +the subject-matter of this volume is avowedly restricted +to debateable topics, and because I choose +those naturalists who are deservedly held in most +esteem to act spokesmen on behalf of such Post-Darwinian +views as appear to me doubtful or erroneous. +Obviously, however, differences of opinion +on particular points ought not to be taken as implying +any failure on my part to recognize the general +scientific authority of these men, or any inability +to appreciate their labours in the varied fields of +Biology.</p> + +<p style="margin-left:95%;">G. J. R.</p> + +<p class="smcap" style="margin-left:5%;">Christ Church, Oxford.</p> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_vii" id="Page_vii">[Pg vii]</a></p> + + + + +<h2>NOTE</h2> + +<p>Some time before his death Mr. Romanes decided +to publish those sections of his work which deal with +Heredity and Utility, as a separate volume, leaving +Isolation and Physiological Selection for the third and +concluding part of <i>Darwin, and after Darwin</i>.</p> + +<p>Most of the matter contained in this part was +already in type, but was not finally corrected for the +press. The alterations made therein are for the most +part verbal.</p> + +<p>Chapter IV was type-written; in it, too, no alterations +of any moment have been made.</p> + +<p>For Chapters V and VI there were notes and isolated +paragraphs not yet arranged. I had promised +during his life to write for Mr. Romanes Chapter V +on the basis of these notes, extending it in such ways +as seemed to be desirable. In that case it would +have been revised and amended by the author and +received his final sanction. Death annulled this +friendly compact; and since, had I written the +chapter myself, it could not receive that imprimatur +which would have given its chief value, I have decided<span class="pagenum"><a name="Page_viii" id="Page_viii">[Pg viii]</a></span> +to arrange the material that passed into my hands +without adding anything of importance thereto. The +substance of Chapters V and VI is therefore entirely +the author's: even the phraseology is his; the arrangement +only is by another hand.</p> + +<p>Such parts of the Preface as more particularly +refer to Isolation and Physiological Selection are +reserved for publication in Part III. A year or more +must elapse before that part will be ready for +publication.</p> + +<p>Mr. F. Howard Collins has, as a kindly tribute to +the memory of the author, read through the proofs. +Messrs. F. Darwin, F. Galton, H. Seebohm, and others, +have rendered incidental assistance. After much +search I am unable to give the references to one or +two passages.</p> + +<p>I have allowed a too flattering reference to myself +to stand, in accordance with a particular injunction of +Mr. Romanes given shortly before that sad day on +which he died, leaving many to mourn the loss of +a personal friend most bright, lovable, and generous-hearted, +and thousands to regret that the hand which +had written so much for them would write for them +no more.</p> + +<p class="smcap" style="margin-left:90%;">C. Ll. M.</p> +<p class="smcap" style="margin-left:5%;">University College, Bristol,</p> +<p class="smcap" style="margin-left:10%;"><i>April, 1894.</i></p> +<hr class="chap" /> +<p class="pagenum"><a name="Page_ix" id="Page_ix">[Pg ix]</a></p> + + + + +<h2>CONTENTS</h2> + + +<p>CHAPTER I.</p> +<p class="toc5"><span class="smcap">Introductory: The Darwinism of Darwin and of the +Post-Darwinian Schools</span><span class="ralign"><a href="#Page_1">1</a></span></p> + +<p>CHAPTER II.</p> +<p class="toc5"><span class="smcap">Characters as Hereditary and Acquired</span> +(<i>Preliminary</i>)<span class="ralign"><a href="#Page_39">39</a></span></p> + +<p>CHAPTER III.</p> +<p class="toc5"><span class="smcap">Characters as Hereditary and Acquired</span> +(<i>Continued</i>)</p> +<p class="toc10">A. <i>Indirect evidence in favour of the Inheritance of Acquired +Characters</i><span class="ralign"><a href="#Page_60">60</a></span></p> +<p class="toc10">B. <i>Inherited effects of Use and of Disuse</i><span class="ralign"><a href="#Page_95">95</a></span></p> + +<p>CHAPTER IV.</p> +<p class="toc5"><span class="smcap">Characters as Hereditary and Acquired</span> (<i>Continued</i>)</p> +<p class="toc10">C. <i>Experimental evidence in favour of the Inheritance of +Acquired Characters</i><span class="ralign"><a href="#Page_103">103</a></span></p> + +<p>CHAPTER V.</p> +<p class="toc5"><span class="smcap">Characters as Hereditary and Acquired</span> (<i>Continued</i>)</p> +<p class="toc10">A. and B. <i>Direct and Indirect Evidence in favour of the +Non-inheritance of Acquired Characters</i><span class="ralign"><a href="#Page_133">133</a></span></p> +<p class="toc10">C. <i>Experimental Evidence as to the Non-inheritance of +Acquired Characters</i><span class="ralign"><a href="#Page_142">142</a></span></p> +<p class="pagenum"><a name="Page_x" id="Page_x">[Pg x]</a></p> + +<p>CHAPTER VI.</p> +<p class="toc5"><span class="smcap">Characters as Hereditary and Acquired</span> (<i>Conclusion</i>)<span class="ralign"><a href="#Page_150">150</a></span></p> + +<p>CHAPTER VII.</p> +<p class="toc5"><span class="smcap">Characters as Adaptive and Specific</span><span class="ralign"><a href="#Page_159">159</a></span></p> + +<p>CHAPTER VIII.</p> +<p class="toc5"><span class="smcap">Characters as Adaptive and Specific</span> (<i>Continued</i>)</p> +<p class="toc10">I. <i>Climate</i><span class="ralign"><a href="#Page_200">200</a></span></p> +<p class="toc10">II. <i>Food</i><span class="ralign"><a href="#Page_217">217</a></span></p> +<p class="toc10">III. <i>Sexual Selection</i><span class="ralign"><a href="#Page_219">219</a></span></p> +<p class="toc10">IV. <i>Isolation</i><span class="ralign"><a href="#Page_223">223</a></span></p> +<p class="toc10">V. <i>Laws of Growth</i><span class="ralign"><a href="#Page_226">226</a></span></p> + +<p>CHAPTER IX.</p> +<p class="toc5"><span class="smcap">Characters as Adaptive and Specific</span> (<i>Continued</i>)<span class="ralign"><a href="#Page_228">228</a></span></p> + +<p>CHAPTER X.</p> +<p class="toc5"><span class="smcap">Characters as Adaptive and Specific</span> (<i>Concluded</i>)<span class="ralign"><a href="#Page_251">251</a></span></p> +<p class="toc10"><i>Summary</i><span class="ralign"><a href="#Page_274">274</a></span></p> + +<p><span class="smcap">Appendix I. On Panmixia</span><span class="ralign"><a href="#Page_291">291</a></span></p> + +<p><span class="smcap">Appendix II. On Characters as Adaptive and Specific</span><span class="ralign"><a href="#Page_307">307</a></span></p> + +<p><span class="smcap">Note A to Page 57</span><span class="ralign"><a href="#Page_333">333</a></span></p> + +<p><span class="smcap">Note B to Page 89</span><span class="ralign"><a href="#Page_337">337</a></span></p> + + + + +<hr class="chap" /> +<p class="pagenum"><a name="Page_xi" id="Page_xi">[Pg xi]</a></p> +<h2>LIST OF ILLUSTRATIONS</h2> + +<p>Portrait of George John Romanes<span class="ralign"><i>Frontispiece</i></span></p> + +<p>Diagram of Prof. Weismann's Theories<span class="ralign"><a href="#Page_43">43</a></span></p> + +<p><span class="smcap">Fig. 1.</span> Guinea pigs, showing gangrene of ears due to injury of +restiform bodies<span class="ralign"><a href="#Page_118">118</a></span></p> + +<p><span class="smcap">Fig. 2.</span> Old Irish Pig (after Richardson)<span class="ralign"><a href="#Page_188">188</a></span></p> + +<p><span class="smcap">Fig. 3.</span> Skulls of Niata Ox and of Wild White Ox<span class="ralign"><a href="#Page_192">192</a></span></p> + +<p><span class="smcap">Fig. 4.</span> Lower teeth of Orang (after Tomes)<span class="ralign"><a href="#Page_261">261</a></span></p> + + + + +<hr class="chap" /> +<p class="pagenum"><a name="Page_1" id="Page_1">[Pg 1]</a></p> +<h2>CHAPTER I.<br /> +<span class="smcap">Introductory: The Darwinism of Darwin, +and of the Post-Darwinian Schools.</span></h2> + + +<p>It is desirable to open this volume of the treatise +on <i>Darwin and after Darwin</i> by taking a brief +survey of the general theory of descent, first, as this +was held by Darwin himself, and next, as it is now +held by the several divergent schools of thought which +have arisen since Darwin's death.</p> + +<p>The most important of the questions in debate is +one which I have already had occasion to mention, +while dealing, in historical order, with the objections +that were brought against the theory of natural +selection during the life-time of Darwin<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">[1]</a>. Here, however, +we must consider it somewhat more in detail, +and justify by quotation what was previously said +regarding the very definite nature of his utterances +upon the matter. This question is whether natural +selection has been the sole, or but the main, cause +of organic evolution.</p> + +<p><span class="pagenum"><a name="Page_2" id="Page_2">[Pg 2]</a></span>Must we regard survival of the fittest as the one +and only principle which has been concerned in the +progressive modification of living forms, or are we to +suppose that this great and leading principle has been +assisted by other and subordinate principles, without +the co-operation of which the results, as presented in +the animal and vegetable kingdoms, could not have +been effected? Now Darwin's answer to this question +was distinct and unequivocal. He stoutly resisted +the doctrine that natural selection was to be regarded +as the only cause of organic evolution. On the other +hand, this opinion was—and still continues to be—persistently +maintained by Mr. Wallace; and it constitutes +the source of all the differences between his +views and those of Darwin. Moreover, up to the time +of Darwin's death, Mr. Wallace was absolutely alone +in maintaining this opinion: the whole body of +scientific thought throughout the world being against +him; for it was deemed improbable that, in the +enormously complex and endlessly varied processes +of organic evolution, only a single principle should be +everywhere and exclusively concerned<a name="FNanchor_2_2" id="FNanchor_2_2"></a><a href="#Footnote_2_2" class="fnanchor">[2]</a>. But since +Darwin's death there has been a great revolution of +biological thought in favour of Mr. Wallace's opinion. +And the reason for this revolution has been, that +his doctrine of natural selection as the sole cause +of organic evolution has received the corroborative +support of Professor Weismann's theory of heredity—which +has been more or less cordially embraced by +a certain section of evolutionists, and which appears to +carry the doctrine in question as a logical corollary, so +far, at all events, as adaptive structures are concerned.</p> + +<p><span class="pagenum"><a name="Page_3" id="Page_3">[Pg 3]</a></span>Now in this opening chapter we shall have to do +merely with a setting forth of Darwin's opinion: +we are not considering how far that opinion ought +to be regarded as having been in any measure displaced +by the results of more recent progress. Such, +then, being the only matter which here concerns us, +I will supply a few brief quotations, to show how +unequivocally Darwin has stated his views. First, +we may take what he says upon the "Lamarckian +factors<a name="FNanchor_3_3" id="FNanchor_3_3"></a><a href="#Footnote_3_3" class="fnanchor">[3]</a>;" and next we may consider what he says +with regard to other factors, or, in general, upon +natural selection not being the sole cause of organic +evolution.</p> + +<blockquote><p>"Changed habits produce an inherited effect, as in the period +of the flowering of plants when transported from one climate to +another. With animals the increased use or disuse of parts has +had a more marked influence<a name="FNanchor_4_4" id="FNanchor_4_4"></a><a href="#Footnote_4_4" class="fnanchor">[4]</a>."</p></blockquote> + +<blockquote><p>"There can be no doubt, from the facts given in this chapter, +that extremely slight changes in the conditions of life sometimes, +probably often, act in a definite manner on our domesticated +productions; and, as the action of changed conditions in +causing indefinite variability is accumulative, so it may be with +their definite action. Hence considerable and definite modifications +of structure probably follow from altered conditions +acting during long series of generations<a name="FNanchor_5_5" id="FNanchor_5_5"></a><a href="#Footnote_5_5" class="fnanchor">[5]</a>."</p></blockquote> + +<blockquote><p>"How, again, can we explain the inherited effects of the use +and disuse of particular organs? The domesticated duck flies<span class="pagenum"><a name="Page_4" id="Page_4">[Pg 4]</a></span> +less and walks more than the wild duck, and its limb bones +have become diminished and increased in a corresponding +manner in comparison with those of the wild duck. A horse is +trained to certain paces, and the colt inherits similar consensual +movements. The domesticated rabbit becomes tame from +close confinement; the dog, intelligent from associating with +man; the retriever is taught to fetch and carry; and these +mental endowments and bodily powers are all inherited. +Nothing in the whole circuit of physiology is more wonderful. +How can the use or disuse of a particular limb or of the brain +affect a small aggregate of reproductive cells, seated in a distant +part of the body, in such a manner that the being developed +from these cells inherits the characters of either one or both +parents?... In the chapters devoted to inheritance, it was +shown that a multitude of newly acquired characters, whether +injurious or beneficial, whether of the lowest or highest vital +importance, are often faithfully transmitted<a name="FNanchor_6_6" id="FNanchor_6_6"></a><a href="#Footnote_6_6" class="fnanchor">[6]</a>."</p></blockquote> + +<blockquote><p>"When discussing special cases, Mr. Mivart passes over the +effects of the increased use and disuse of parts, which I have +always maintained to be highly important, and have treated in +my 'Variation under Domestication' at greater length than, +as I believe, any other writer<a name="FNanchor_7_7" id="FNanchor_7_7"></a><a href="#Footnote_7_7" class="fnanchor">[7]</a>."</p></blockquote> + +<p>So much for the matured opinion of Darwin touching +the validity of the theory of use-inheritance. Turning +now to his opinion on the question whether or not +there are yet any further factors concerned in the +process of organic evolution, I think it will be sufficient +to quote a single passage from the <i>Origin of Species</i>. +The first paragraph of the "Conclusion" is devoted +to a <i>résumé</i> of his views upon this matter, and consists +of the following most emphatic words.</p> + +<blockquote><p>"I have now recapitulated the facts and considerations which +have thoroughly convinced me that species have been modified, +during a long course of descent. This has been effected chiefly +through the natural selection of numerous successive, slight,<span class="pagenum"><a name="Page_5" id="Page_5">[Pg 5]</a></span> +favourable variations; aided in an important manner by the +inherited effects of the use and disuse of parts; and in an unimportant +manner, that is in relation to adaptive structures, +whether past or present, by the direct action of external conditions, +and by variations which seem to us in our ignorance to +arise spontaneously. It appears that I formerly underrated the +frequency and value of these latter forms of variation, as leading +to permanent modifications of structure independently of natural +selection. But as my conclusions have lately been much misrepresented, +and it has been stated that I attribute the modification +of species exclusively to natural selection, I may be permitted +to remark that in the first edition of this work, and subsequently, +I placed in a most conspicuous position—namely, at the close +of the Introduction—the following words: 'I am convinced that +natural selection has been the main, but not the exclusive means +of modification.' This has been of no avail. Great is the +power of steady misrepresentation; but the history of science +shows that fortunately this power does not long endure."</p></blockquote> + +<p>In the whole range of Darwin's writings there +cannot be found a passage so strongly worded as +this: it presents the only note of bitterness in all +the thousands of pages which he has published. +Therefore I do not think it is necessary to supply +any further quotations for the purpose of proving +the state of his opinion upon the point in question. +But, be it carefully noted, from this great or radical +difference of opinion between the joint originators of +the theory of natural selection, all their other differences +of opinion arise; and seeing that since the +death of Darwin a large number of naturalists have +gone over to the side of Wallace, it seems desirable +here to state categorically what these other or sequent +points of difference are. Without at present discussing +them, therefore, I will merely set them out in a +tabular form, in order that a clear perception may be<span class="pagenum"><a name="Page_6" id="Page_6">[Pg 6]</a></span> +gained of their logical connexion with this primary +point of difference.</p> + +<div class="center" style="margin-left:10%; margin-right:10%;"> +<table border="1" cellpadding="4" cellspacing="0" summary=""> +<tr><td align="center"><i>The Theory of Natural Selection +according to Darwin.</i></td> +<td align="center"><i>The theory of Natural Selection +according to Wallace.</i></td></tr> + +<tr><td align="left">Natural Selection has been +the main means of modification, +not excepting the case of +Man.</td> +<td align="left">Natural Selection has been +the sole means of modification, +excepting in the case of Man.</td></tr> + +<tr><td align="left">(<i>a</i>) Therefore it is a question +of evidence whether the Lamarckian +factors have co-operated.</td> +<td align="left">(<i>a</i>) Therefore it is antecedently +impossible that the +Lamarckian factors can have +co-operated.</td></tr> + +<tr><td align="left">(<i>b</i>) Neither all species, nor, +<i>a fortiori</i>, all specific characters, +have been due to +natural selection.</td> +<td align="left">(<i>b</i>) Not only all species, but +all specific characters, must +necessarily have been due to +natural selection.</td></tr> + +<tr><td align="left">(<i>c</i>) Thus the principle of +Utility is not of universal application, +even where species +are concerned.</td> +<td align="left">(<i>c</i>) Thus the principle of +Utility must necessarily be of +universal application, where +species are concerned.</td></tr> + +<tr><td align="left">(<i>d</i>) Thus, also, the suggestion +as to Sexual Selection, or +any other supplementary cause +of modification, may be entertained; +and, as in the case of +the Lamarckian factors, it is a +question of evidence whether, +or how far, they have co-operated.</td> +<td align="left">(<i>d</i>) Thus, also, the suggestion +as to Sexual Selection, or +of any other supplementary +cause of modification, must be +ruled out; and, as in the case +of the Lamarckian factors, +their co-operation deemed impossible.</td></tr> + +<tr><td align="left">(<i>e</i>) No detriment arises to +the theory of natural selection +as a theory of the origin of +species by entertaining the +possibility, or the probability, +of supplementary factors.</td> +<td align="left">(<i>e</i>) The possibility—and, <i>a +fortiori</i> the probability—of any +supplementary factors cannot +be entertained without serious +detriment to the theory of +natural selection, as a theory +of the origin of species.</td></tr> + +<tr><td align="left">(<i>f</i>) Cross-sterility in species +cannot possibly be due to +natural selection.</td> +<td align="left">(<i>f</i>) Cross-sterility in species +is probably due to natural +selection<a name="FNanchor_8_8" id="FNanchor_8_8"></a><a href="#Footnote_8_8" class="fnanchor">[8]</a>.</td></tr> +</table></div> + +<p><span class="pagenum"><a name="Page_7" id="Page_7">[Pg 7]</a></span>As it will be my endeavour in the ensuing chapters +to consider the rights and the wrongs of these antithetical +propositions, I may reserve further quotations +from Darwin's works, which will show that the above +is a correct epitome of his views as contrasted with +those of Wallace and the Neo-Darwinian school of +Weismann. But here, where the object is merely +a statement of Darwin's theory touching the points +in which it differs from those of Wallace and Weismann, +it will be sufficient to set forth these points of +difference in another and somewhat fuller form. So +far then as we are at present concerned, the following +are the matters of doctrine which have been +clearly, emphatically, repeatedly, and uniformly expressed +throughout the whole range of Darwin's +writings.</p> + +<p>1. That natural selection has been the main means +of modification.</p> + +<p>2. That, nevertheless, it has not been the only +means; but has been supplemented or assisted by the +co-operation of other causes.</p> + +<p>3. That the most "important" of these other causes +has been the inheritance of functionally-produced +modifications (use-inheritance); but this only because +the transmission of such modifications to progeny must +always have had immediate reference to <i>adaptive</i> +ends, as distinguished from merely useless change.</p> + +<p>4. That there are sundry other causes which lead<span class="pagenum"><a name="Page_8" id="Page_8">[Pg 8]</a></span> +to merely useless change—in particular, "the direct +action of external conditions, and variations which +seem to us in our ignorance to arise spontaneously."</p> + +<p>5. Hence, that the "principle of utility," far from +being of universal occurrence in the sphere of animate +nature, is only of what may be termed highly general +occurrence; and, therefore, that certain other advocates +of the theory of natural selection were mistaken in +representing the universality of this principle as +following by way of necessary consequence from that +theory.</p> + +<p>6. Cross-sterility in species cannot possibly be due +to natural selection; but everywhere arises as a result +of some physiological change having exclusive reference +to the sexual system—a change which is +probably everywhere due to the same cause, although +what this cause could be Darwin was confessedly +unable to suggest.</p> + +<p>Such, then, was the theory of evolution as held by +Darwin, so far as the points at present before us are +concerned. And, it may now be added, that the +longer he lived, and the more he pondered these +points, the less exclusive was the <i>rôle</i> which he assigned +to natural selection, and the more importance +did he attribute to the supplementary factors above +named. This admits of being easily demonstrated +by comparing successive editions of his works; a +method adopted by Mr. Herbert Spencer in his +essay on the <i>Factors of Organic Evolution</i>.</p> + +<p>My object in thus clearly defining Darwin's attitude +regarding these sundry points is twofold.</p> + +<p>In the first place, with regard to merely historical +accuracy, it appears to me undesirable that naturalists<span class="pagenum"><a name="Page_9" id="Page_9">[Pg 9]</a></span> +should endeavour to hide certain parts of Darwin's +teaching, and give undue prominence to others. In +the second place, it appears to me still more undesirable +that this should be done—as it usually is +done—for the purpose of making it appear that +Darwin's teaching did not really differ very much +from that of Wallace and Weismann on the important +points in question. I myself believe that Darwin's +judgement with regard to all these points will +eventually prove more sound and accurate than +that of any of the recent would-be improvers upon +his system; but even apart from this opinion +of my own it is undesirable that Darwin's views +should be misrepresented, whether the misrepresentation +be due to any unfavourable bias against one +side of his teaching, or to sheer carelessness in the +reading of his books. Yet the new school of evolutionists, +to which allusion has now so frequently been +made, speak of their own modifications of Darwin's +teaching as "pure Darwinism," in contradistinction +to what they call "Lamarckism." In other words, +they represent the principles of "Darwinism" as +standing in some kind of opposition to those of +"Lamarckism": the Darwinian principle of natural +selection, they think, is in itself enough to account for +all the facts of adaptation in organic nature. Therefore +they are eager to dispense with the Lamarckian +principle of the inherited effects of use and disuse, +together with the direct influence of external conditions +of life, and all or any other causes of modification which +either have been, or in the future may possibly be, +suggested. Now, of course, there is no reason why +any one should not hold these or any other opinions<span class="pagenum"><a name="Page_10" id="Page_10">[Pg 10]</a></span> +to which his own independent study of natural science +may lead him; but it appears to me that there is +the very strongest reason why any one who deviates +from the carefully formed opinions of such a man +as Darwin, should above all things be careful to +be absolutely fair in his representations of them; +he should be scrupulously jealous, so to speak, of +not letting it appear that he is unjustifiably throwing +over his own opinions the authority of Darwin's +name.</p> + +<p>But in the present case, as we have seen, not only +do the Neo-Darwinians strain the teachings of Darwin; +they positively reverse those teachings—representing +as anti-Darwinian the whole of one side of +Darwin's system, and calling those who continue to +accept that system in its entirety by the name +"Lamarckians." I know it is sometimes said by +members of this school, that in his utilization of +Lamarckian principles as accessory to his own, +Darwin was actuated by motives of "generosity." But +a more preposterous suggestion could not well be +made. We may fearlessly challenge any one who +speaks or writes in such a way, to show any other +instance where Darwin's great generosity of disposition +had the effect of influencing by one hair's +breadth his still greater loyalty to truth. Moreover, +and with special regard to this particular case, I +would point out that in no one of his many allusions +to, and often lengthy <span class="correction" title="Transcriber's Note: 'dicussions' in the text.">discussions</span> of, these so-called +Lamarckian principles, does he ever once +introduce the name of Lamarck; while, on the other +hand, in the only places where he does so—whether +in his books or in his now published letters—he<span class="pagenum"><a name="Page_11" id="Page_11">[Pg 11]</a></span> +does so in order to express an almost contemptuous +dissatisfaction, and a total absence of obligation. +Hence, having regard to the "generosity" with +which he always acknowledged obligations, there +can be no reasonable doubt that Darwin was not in +the smallest degree influenced by the speculative +writings of Lamarck; or that, even if Lamarck had +never lived, the <i>Origin of Species</i> would have differed +in any single particular from the form in which it +now stands. Finally, it must not be forgotten that +Darwin's acceptance of the theory of use-inheritance +was vitally essential to his theory of Pangenesis—that +"beloved child" over which he had "thought +so much as to have lost all power of judging it<a name="FNanchor_9_9" id="FNanchor_9_9"></a><a href="#Footnote_9_9" class="fnanchor">[9]</a>."</p> + +<p>What has just been said touching the relations +between Darwin's theory and that of Lamarck, +applies with equal force to the relations between +Darwin's theory and any other theory appertaining +to evolution which has already been, or may +hereafter be propounded. Yet so greatly have +some of the Neo-Darwinians misunderstood the teachings +of Darwin, that they represent as "Darwinian +heresy" any suggestions in the way of factors "supplementary +to," or "co-operative with" natural selection. +Of course, if these naturalists were to avow themselves +followers of Wallace, instead of followers of Darwin, +they would be perfectly justified in repudiating any +such suggestions as, <i>ipso facto</i> heretical. But, as we +have now seen, through all his life Darwin differed +from Wallace with regard to this very point; and +therefore, unlike Wallace, he was always ready to entertain +"additional suggestions" regarding the causes<span class="pagenum"><a name="Page_12" id="Page_12">[Pg 12]</a></span> +of organic evolution—several of which, indeed, he +himself supplied. Hence we arrive at this curious +state of matters. Those biologists who of late years +have been led by Weismann to adopt the opinions of +Wallace, represent as anti-Darwinian the opinions of +other biologists who still adhere to the unadulterated +doctrines of Darwin. Weismann's <i>Essays on Heredity</i> +(which argue that natural selection is the only possible +cause of adaptive modification) and Wallace's +work on <i>Darwinism</i> (which in all the respects +where any charge of "heresy" is concerned directly +contradicts the doctrine of Darwin)—these are the +writings which are now habitually represented by the +Neo-Darwinians as setting forth the views of +Darwin in their "pure" form. The result is that, +both in conversation and in the press, we habitually +meet with complete inversions of the truth, which +show the state of confusion into which a very simple +matter has been wrought by the eagerness of certain +naturalists to identify the views of Darwin with those +of Wallace and Weismann. But we may easily +escape this confusion, if we remember that wherever +in the writings of these naturalists there occur such +phrases as "pure Darwinism" we are to understand +pure <i>Wallaceism</i>, or the pure theory of natural +selection to the exclusion of any supplementary +theory. Therefore it is that for the sake of clearness +I coined, several years ago, the terms "Neo-Darwinian" +and "Ultra-Darwinian" whereby to designate +the school in question.</p> + +<hr class="tb" /> + +<p>So much, then, for the Darwinism of Darwin, as +contrasted with the Darwinism of Wallace, or, what<span class="pagenum"><a name="Page_13" id="Page_13">[Pg 13]</a></span> +is the same thing, of the Neo-Darwinian school of +Weismann. Next we may turn, by way of antithesis, +to the so-called "Neo-Lamarckian" school of the +United States. For, by a curious irony of fate, while +the Neo-Darwinian school is in Europe seeking to +out-Darwin Darwin by assigning an exclusive prerogative +to natural selection in both kingdoms of +animate nature, the Neo-Lamarckian school is in +America endeavouring to reform Darwinism in +precisely the opposite direction—viz. by transferring +the sovereignty from natural selection to the +principles of Lamarck. Without denying to natural +selection a more or less important part in the process +of organic evolution, members of this school believe +that much greater importance ought to be assigned +to the inherited effects of use and disuse than was +assigned to these agencies by Darwin. Perhaps +this noteworthy state of affairs, within a decade of +Darwin's death, may lead us to anticipate that his +judgement—standing, as it does, between these two +extremes—will eventually prove the most accurate +of all, with respect to the relative importance of +these factors of evolution. But, be this as it may, +I must now offer a few remarks upon the present +position of the matter.</p> + +<p>In the first place, to any one who (with Darwin and +against Weismann) admits not only the abstract possibility, +but an actual working, of the Lamarckian +factors, it becomes difficult to determine, even +approximately, the degrees of value which ought to +be ascribed to them and to natural selection respectively. +For, since the results are in both cases identical +in kind (as, adaptive changes of organic types), where<span class="pagenum"><a name="Page_14" id="Page_14">[Pg 14]</a></span> +both sets of causes are supposed to be in operation +together, we have no means of estimating the relative +shares which they have had in bringing about these +results. Of course there are large numbers of cases +where it cannot possibly be supposed that the +Lamarckian factors have taken any part at all in producing +the observed effects; and therefore in such cases +there is almost full agreement among evolutionists in +theoretically ascribing such effects to the exclusive +agency of natural selection. Of such, for instance, are +the facts of protective colouring, of mimicry, of the +growth of parts which, although <i>useful</i>, are never +<i>active</i> (e.g. shells of mollusks, hard coverings of seeds), +and so on. But in the majority of cases where +adaptive structures are concerned, there is no means +of discriminating between the influences of the +Lamarckian and the Darwinian factors. Consequently, +if by the Neo-Lamarckian school we understand +all those naturalists who assign any higher +importance to the Lamarckian factors than was +assigned to them by Darwin, we may observe that +members of this school differ very greatly among +themselves as to the degree of importance that ought +to be assigned. On the one hand we have, in Europe, +Giard, Perrier, and Eimer, who stand nearer to Darwin +than do a number of the American representatives—of +whom the most prominent are Cope, Osborn, +Packard, Hyatt, Brooks, Ryder, and Dall. The most +extreme of these is Professor Cope, whose collection +of essays entitled <i>The Origin of the Fittest</i>, as well as +his more recent and elaborate monograph on <i>The +Development of the Hard Parts of the Mammalia</i>, +represent what appears even to some other members<span class="pagenum"><a name="Page_15" id="Page_15">[Pg 15]</a></span> +of his school an extravagant estimate of the importance +of Lamarckian principles.</p> + +<p>But the most novel, and in many respects the +most remarkable school of what may be termed +Anti-selectionists is one which is now (1894) rapidly +increasing both in numbers and in weight, not only +in the New World, but also in Germany, and to a +lesser extent, in Great Britain.</p> + +<p>This school, without being either Lamarckian or +Darwinian (for its individual members differ widely +from one another in these respects) maintains a +principle which it deems of more importance than +either use-inheritance or natural selection. This principle +it calls Self-adaptation. It is chiefly botanists +who constitute this school, and its principal representatives, +in regard to authority, are Sachs, Pfeffer and +Henslow.</p> + +<p>Apart from topics which are to be dealt with in +subsequent chapters, the only matters of much importance +which have been raised in the Post-Darwinian +period are those presented by the theories of Geddes, +Cope, Hyatt, and others, and certain more or less +novel ideas set forth in Wallace's <i>Darwinism</i>.</p> + +<p>Mr. Geddes has propounded a new theory of the +origin of species, which in his judgement supersedes to +a large extent the theory of natural selection. He has +also, in conjunction with Mr. Thomson, propounded +a theory of the origin of sex. For my own part, I +cannot see that these views embody any principles +or suggestions of a sufficiently definite kind to +constitute them theories at all. In this respect the +views of Mr. Geddes resemble those of Professors +Cope, Hyatt, and others, on what they term "the<span class="pagenum"><a name="Page_16" id="Page_16">[Pg 16]</a></span> +law of acceleration and retardation." In all these +cases, so far as I can see, the so-called explanations +are not in fact any explanations; but either a mere +re-statement of the facts, or else an enunciation of +more or less meaningless propositions. Thus, when +it is said that the evolution of any given type has +been due to the "acceleration of growth-force" with +respect to some structures, and the "retardation of +growth-force" with respect to others, it appears +evident that we have not any real explanation in terms +of causality; we have only the form of an explanation +in the terms of a proposition. All that has been done +is to express the fact of evolution in somewhat obscure +phraseology, since the very thing we want to know +about this fact is—What are the causes of it as a fact, +or the reasons which have led to the increase of some +of the parts of any given type, and the concomitant +decrease of others? It is merely the facts themselves +that are again presented by saying that the development +has been in the one case accelerated, while in +the other it has been retarded<a name="FNanchor_10_10" id="FNanchor_10_10"></a><a href="#Footnote_10_10" class="fnanchor">[10]</a>.</p> + +<p>So much for what may be termed this New +World theory of the origin of species: it is a mere +re-statement of the facts. Mr. Geddes' theory, on the<span class="pagenum"><a name="Page_17" id="Page_17">[Pg 17]</a></span> +other hand, although more than a mere re-statement +of the facts, appears to me too vague to be of any +explanatory service. His view is that organic evolution +has everywhere depended upon an antagonism, +within the limits of the same organism, between the +processes of nutrition and those of reproduction. But +although he is thus able hypothetically to explain +certain facts—such as the shortening of a flower-spike +into a composite flower—the suggestion is obviously +inadequate to meet, even hypothetically, most of the +facts of organic evolution, and especially the development +of <i>adaptive</i> structures. Therefore, it seems to me, +we may dismiss it even as regards the comparatively +few facts which it might conceivably explain—seeing +that these same facts may be equally well explained +by the causes which are already known to operate +in other cases. For it is the business of natural +selection to ensure that there shall nowhere be any +needless expenditure of vital energy, and, consequently, +that everywhere the balance between nutrition +and reproduction shall be most profitably adjusted.</p> + +<p>Similarly with respect to the theory of the <i>Origin +of Sex</i>, I am unable to perceive even this much of +scientific relevancy. As stated by its authors the +theory is, that the female is everywhere "anabolic," +as compared with the male, which is "katabolic." By +anabolic is meant comparative inactivity of protoplasmic +change due to a nutritive winding up of +molecular constitution, while by katabolic is meant +the opposite condition of comparative activity due to +a dynamic running down of molecular constitution. +How, then, can the <i>origin</i> of sex be explained, or the +<i>causes</i> which led to the differentiation of the sexes be<span class="pagenum"><a name="Page_18" id="Page_18">[Pg 18]</a></span> +shown by saying that the one sex is anabolic and the +other katabolic? In so far as these verbal statements +serve to express what is said to be a general fact—namely, +that the female sexual elements are less +mobile than the male—they merely serve to re-state +this general fact in terminology which, as the authors +themselves observe, is "unquestionably ugly." But +in so far as any question of <i>origin</i> or <i>causality</i> is concerned, +it appears to me that there is absolutely no +meaning in such statements. They belong to the +order of merely formal explanations, as when it is said +that the toxic qualities of morphia are due to this +drug possessing a soporific character.</p> + +<p>Much the same, in my opinion, has to be said of +the Rev. G. Henslow's theory of the origin of species +by what he terms "self-adaptation." Stated briefly +his view is that there is no sufficient evidence of +natural selection as a <i>vera causa</i>, while there is very +abundant evidence of adjustments occurring without +it, first in individual organisms, and next, by inheritance +of acquired characters, in species. Now, much +that he says in criticism of the selection theory is of +considerable interest as such; but when we pass +from the critical to the constructive portions of his +books and papers, we again meet with the want of +clearness in thought between a statement of facts +in terms of a proposition, and an explanation of +them in those of causality. Indeed, I understand +from private correspondence, that Mr. Henslow himself +admits the validity of this criticism; for in +answer to my questions,—"How does Self-adaptation +work in each case, and why should protoplasm +be able to <i>adapt itself</i> into the millions of diverse<span class="pagenum"><a name="Page_19" id="Page_19">[Pg 19]</a></span> +mechanisms in nature?"—he writes. "Self-adaptation +does not profess to be a <i>vera causa</i> at all; for the +true causes of variation can only be found in the +answer to your [above] questions, and I must say +at once, <i>these questions cannot be answered</i>." That +is, they cannot be answered on the hypothesis of +self-adaptation, which is therefore a statement of +the facts of adaptation as distinguished from an +explanation of them. Nevertheless, two things have +here to be noted. In the first place, the statement +of facts which Mr. Henslow has collected is of considerable +theoretical importance as tending to show +that there are probably causes of an internal kind +(i. e. other than natural selection) which have been +largely concerned in the adaptive modification of +plants. And, in the second place, it is not quite true +that the theory of self-adaptation is, as its author +says in the sentences above quoted, a mere statement +of the facts of adaptation, without any attempt at +explaining their causes. For in his published words +he does attempt to do so<a name="FNanchor_11_11" id="FNanchor_11_11"></a><a href="#Footnote_11_11" class="fnanchor">[11]</a>. And, although I think +his attempt is a conspicuous failure, I ought in fairness +to give examples of it. His books are almost +exclusively concerned in an application of his theory +to the mechanisms of flowers for securing their own +fertilization. These mechanisms he ascribes, in the +case of entomophylous flowers, to the "thrusts," +"strains," and other "irritations" supplied to the +flowers by their insect visitors, and consequent "reactions" +of the vegetable "protoplasm." But no +attempt is made to show why these "reactions"<span class="pagenum"><a name="Page_20" id="Page_20">[Pg 20]</a></span> +should be of an <i>adaptive</i> kind, so as to build up +the millions of diverse and often elaborate mechanisms +in question—including not only forms and movements, +but also colours, odours, and secretions. For +my own part I confess that, even granting to an +ultra-Lamarckian extent the inheritance of acquired +characters, I could conceive of "self-adaptation" alone +producing all such innumerable and diversified adjustments +only after seeing, with Cardinal Newman, an +angel in every flower. Yet Mr. Henslow somewhat +vehemently repudiates any association between his +theory and that of teleology.</p> + +<p>On the whole, then, I regard all the works which +are here classed together (those by Cope, Geddes, +and Henslow), as resembling one another both in +their merits and defects. Their common merits lie +in their erudition and much of their criticism, while +their common defects consist on the one hand in not +sufficiently distinguishing between mere statements +and real explanations of facts, and, on the other, in +not perceiving that the theories severally suggested +as substitutes for that of natural selection, even if +they be granted true, could be accepted only as +co-operative factors, and by no stretch of logic as +substitutes.</p> + +<hr class="tb" /> + +<p>Turning now to Mr. Wallace's work on <i>Darwinism</i>, +we have to notice, in the first place, that its doctrine +differs from "Darwinism" in regard to the important +dogma which it is the leading purpose of that work +to sustain—namely, that "the law of utility" is, to all +intents and purposes, universal, with the result that +natural selection is virtually the only cause of organic<span class="pagenum"><a name="Page_21" id="Page_21">[Pg 21]</a></span> +evolution. I say "to all intents and purposes," or +"virtually," because Mr. Wallace does not expressly +maintain the abstract impossibility of laws and +causes other than those of utility and natural selection; +indeed, at the end of his treatise, he quotes +with approval Darwin's judgement, that "natural +selection has been the most important, but not the +exclusive means of modification." Nevertheless, as he +nowhere recognizes any other law or cause of adaptive +evolution<a name="FNanchor_12_12" id="FNanchor_12_12"></a><a href="#Footnote_12_12" class="fnanchor">[12]</a>, he practically concludes that, on inductive +or empirical grounds, there <i>is</i> no such other law +or cause to be entertained—until we come to the particular +case of the human mind. But even in making +this one particular exception—or in representing that +some other law than that of utility, and some other +cause than that of natural selection, must have been +concerned in evolving the mind of man—he is not +approximating his system to that of Darwin. On the +contrary, he is but increasing the divergence, for, of +course, it was Darwin's view that no such exception +could be legitimately drawn with respect to this +particular instance. And if, as I understand must +be the case, his expressed agreement with Darwin +touching natural selection not being the only cause +of adaptive evolution has reference to this point, the +quotation is singularly inapt.</p> + +<p>Looking, then, to these serious differences between +his own doctrine of evolution—both organic and +mental—and that of Darwin, I cannot think that<span class="pagenum"><a name="Page_22" id="Page_22">[Pg 22]</a></span> +Mr. Wallace has chosen a suitable title for his book; +because, in view of the points just mentioned, it is +unquestionable that <i>Darwinism</i> differs more widely +from the <i>Origin of Species</i> than does the <i>Origin of +Species</i> from the writings of the Neo-Lamarckians. +But, passing over this merely nominal matter, a few +words ought to be added on the very material +question regarding the human mind. In subsequent +chapters the more general question, or that which +relates to the range of utility and natural selection +elsewhere will be fully considered.</p> + +<p>Mr. Wallace says,—</p> + +<blockquote><p>"The immense interest that attaches to the origin of the +human race, and the amount of misconception which prevails +regarding the essential teachings of Darwin's theory on the +question, as well as regarding my own special views upon it, +induce me to devote a final chapter to its discussion."</p></blockquote> + +<p>Now I am not aware that there is any misconception +in any quarter as to the essential teachings +of Darwin's theory on this question. Surely +it is rather the case that there is a very general and +very complete understanding on this point, both by +the friends and the foes of Darwin's theory—so much +so, indeed, that it is about the only point of similar +import in all Darwin's writings of which this can +be said. Mr. Wallace's "special views" on the +other hand are, briefly stated, that certain features, +both of the morphology and the psychology of man, +are inexplicable by natural selection—or indeed by +any other cause of the kind ordinarily understood +by the term natural: they can be explained only +by supposing "the intervention of some distinct +individual intelligence," which, however, need not<span class="pagenum"><a name="Page_23" id="Page_23">[Pg 23]</a></span> +necessarily be "one Supreme Intelligence," but some +other order of Personality standing anywhere in +"an infinite chasm between man and the Great Mind +of the universe<a name="FNanchor_13_13" id="FNanchor_13_13"></a><a href="#Footnote_13_13" class="fnanchor">[13]</a>." Let us consider separately the +corporeal and the mental peculiarities which are given +as justifying this important conclusion.</p> + +<p>The bodily peculiarities are the feet, the hands, the +brain, the voice, and the naked skin.</p> + +<p>As regards the feet Mr. Wallace writes, "It is +difficult to see why the prehensile power [of the great +toe] should have been taken away," because, although +"it may not be compatible with perfectly easy erect +locomotion," "how can we conceive that early man, +<i>as an animal</i>, gained anything by purely erect +locomotion<a name="FNanchor_14_14" id="FNanchor_14_14"></a><a href="#Footnote_14_14" class="fnanchor">[14]</a>?" But surely it is not difficult to conceive +this. In the proportion that our simian +progenitors ceased to be arboreal in their habits (and +there may well have been very good utilitarian reasons +for such a change of habitat, analogous to those +which are known to have occurred in the phylogenesis +of countless other animals), it would clearly have been +of advantage to them that their already semi-erect +attitude should have been rendered more and more +erect. To name one among several probabilities, the +more erect the attitude, and the more habitually it was +assumed, the more would the hands have been +liberated for all the important purposes of manipulation. +The principle of the physiological division +of labour would thus have come more and more into +play: natural selection would therefore have rendered +the upper extremities more and more suited to the<span class="pagenum"><a name="Page_24" id="Page_24">[Pg 24]</a></span> +execution of these purposes, while at the same time +it would have more and more adapted the lower ones +to discharging the sole function of locomotion. For +my own part, I cannot perceive any difficulty about +this: in fact, there is an admirable repetition of the +process in the ontogeny of our own children<a name="FNanchor_15_15" id="FNanchor_15_15"></a><a href="#Footnote_15_15" class="fnanchor">[15]</a>.</p> + +<p>Next, with regard to the hand, Mr. Wallace says, +that it "contains latent capacities which are unused +by savages, and must have been even less used by +palaeolithic man and his still ruder predecessors." +Thus, "it has all the appearance of an organ prepared +for the use of civilized man<a name="FNanchor_16_16" id="FNanchor_16_16"></a><a href="#Footnote_16_16" class="fnanchor">[16]</a>." Even if this be true, +however, it would surely be a dangerous argument +to rely upon, seeing that we cannot say of how much +importance it may have been for early man—or even +apes—to have had their power of manipulation progressively +improved. But is the statement true? It +appears to me that if Mr. Wallace had endeavoured +to imitate the manufactures that were practised by +"palaeolithic man," he would have found the very +best of reasons for cancelling his statement. For it +is an extremely difficult thing to chip a flint into the +form of an arrow-head: when made, the suitable +attachment of it to a previously prepared arrow is no +easy matter: neither a bow nor a bow-string could +have been constructed by hands of much less perfection +than our own: and the slaying of game with +the whole apparatus, when it has been constructed, +requires a manual dexterity which we may be perfectly<span class="pagenum"><a name="Page_25" id="Page_25">[Pg 25]</a></span> +certain that Mr. Wallace—unless he has +practised the art from boyhood—does not possess.</p> + +<p>So it is with his similar argument that the human +voice is more "powerful," more "flexible," and presents +a greater "range" and "sweetness" than the +needs of savage life can be held to require. The futility +of this argument is self-evident as regards "power." +And although its weakness is not so obvious with +respect to the other three qualities which are named, +need we go further than the closely analogous case of +certain birds to show the precariousness of arguing +from such facts of organic nature to the special +operation of "a superior intelligence"? I can hardly +suppose that Mr. Wallace will invoke any such +agency for the purpose of explaining the "latent +capacities" of the voice of a parrot. Yet, in many respects, +these are even more wonderful than those +of the human voice, albeit in a wild state they are +"never required or used<a name="FNanchor_17_17" id="FNanchor_17_17"></a><a href="#Footnote_17_17" class="fnanchor">[17]</a>."</p> + +<p>Once more, with regard to the naked skin, it seems +sufficient to quote the following passage from the first +edition of the <i>Descent of Man</i>.</p> + +<blockquote><p>"The Rev. T. R. Stebbing, in commenting on this view, +remarks, that had Mr. Wallace 'employed his usual ingenuity +on the question of man's hairless skin, he might have seen +the possibility of its selection through its superior beauty, +or the health attaching to superior cleanliness. At any rate +it is surprising that he should picture to himself a superior<span class="pagenum"><a name="Page_26" id="Page_26">[Pg 26]</a></span> +intelligence plucking the hair from the backs of savage men +(to whom, according to his own account, it would have been useful +and beneficial), in order that the descendants of the poor +shorn wretches might, after many deaths from cold and damp +in the course of many generations,' have been forced to raise +themselves in the scale of civilization through the practice of +various arts, in the manner indicated by Mr. Wallace<a name="FNanchor_18_18" id="FNanchor_18_18"></a><a href="#Footnote_18_18" class="fnanchor">[18]</a>."</p></blockquote> + +<p>To this it may be added that the Chimpanzee +"Sally" was largely denuded of hair, especially on +the back, or the part of "man's organization" on +which Mr. Wallace lays special stress, as being in this +respect out of analogy with other mammalia<a name="FNanchor_19_19" id="FNanchor_19_19"></a><a href="#Footnote_19_19" class="fnanchor">[19]</a>.</p> + +<p>Lastly, touching his statement that the brain of +savage man is both quantitatively and qualitatively +in advance of his requirements, it is here also sufficient +to refer to Darwin's answer, as given in the <i>Descent of +Man</i>. Mr. Wallace, indeed, ignores this answer in his +recent re-publication of the argument; but it is impossible +to understand why he should have done so. +To me, at all events, it seems that one out of several +considerations which Darwin advances is alone +sufficient to show the futility of this argument. +I allude to the consideration that the power of +forming abstract ideas with the complex machinery +of language as the vehicle of their expression, is +probably of itself enough to account for both the +mass and the structure of a savage's brain. But this +leads us to the second division of Mr. Wallace's argument,<span class="pagenum"><a name="Page_27" id="Page_27">[Pg 27]</a></span> +or that derived from the mental endowments +of mankind.</p> + +<p>Here the peculiarities called into evidence are, "the +Mathematical Faculty," "the Artistic Faculties," and +"the Moral Sense." With regard to the latter, he +avows himself a member of the intuitional school of +ethics; but does not prove a very powerful advocate +as against the utilitarian<a name="FNanchor_20_20" id="FNanchor_20_20"></a><a href="#Footnote_20_20" class="fnanchor">[20]</a>.</p> + +<p>It comes, then, to this. According to Mr. Wallace's<span class="pagenum"><a name="Page_28" id="Page_28">[Pg 28]</a></span> +eventual conclusion, man is to be separated from the +rest of organic nature, and the steady progress of +evolution by natural causes is to be regarded as +stopped at its final stage, because the human mind +presents the faculties of mathematical calculation and +aesthetic perception. Surely, on antecedent grounds +alone, it must be apparent that there is here no kind +of proportion between the conclusion and the <i>data</i> from +which it is drawn. That we are not confined to +any such grounds, I will now try to show.</p> + +<p>Let it be remembered, however, that in the following +brief criticism I am not concerned with the issue as +to whether, or how far, the "faculties" in question +have owed their origin or their development to +<i>natural selection</i>. I am concerned only with the +doctrine that in order to account for such and such +particular "faculty" of the human mind, some order +of causation must be supposed other than what we +call natural. I am not a Neo-Darwinist, and so +have no desire to make "natural selection" synonymous +with "natural causation" throughout the whole +domain of life and of mind. And I quite agree +with Mr. Wallace that, at any rate, the "aesthetic +faculty" cannot conceivably have been produced by +natural selection—seeing that it is of no conceivable +life-serving value in any of the stages of its growth. +Moreover, it appears to me that the same thing has to +be said of the play instincts, sense of the ludicrous, and +sundry other "faculties" of mind among the lower +animals. It being thus understood that I am not +differing from Mr. Wallace where he imposes "limits" +on the powers of natural selection, but only where he +seems to take for granted that this is the same thing<span class="pagenum"><a name="Page_29" id="Page_29">[Pg 29]</a></span> +as imposing limits on the powers of natural causation, +my criticism is as follows.</p> + +<p>In the first place, it is a psychological fallacy to +regard the so-called "faculties" of mind as analogous +to "organs" of the body. To classify the latter with +reference to the functions which they severally perform +is to follow a natural method of classification. But +it is an artificial method which seeks to partition +mental <i>faculty</i> into this, that, and the other mental +<i>faculties</i>. Like all other purely artificial classifications, +this one has its practical uses; but, also like +them, it is destitute of philosophical meaning. This +statement is so well recognized by psychologists, that +there is no occasion to justify it. But I must remark +that any cogency which Mr. Wallace's argument may +appear to present, arises from his not having recognized +the fact which the statement conveys. For, had he +considered the mind as a whole, instead of having +contemplated it under the artificial categories of +constituent "faculties," he would probably not have +laid any such special stress upon some of the latter. +In other words, he would have seen that the general +development of the human mind as a whole has +presumably involved the growth of those conventionally +abstracted parts, which he regards as really +separate endowments. Or, if he should find it easier +to retain the terms of his metaphor, we may answer +him by saying that the "faculties" of mind are +"correlated," like "organs" of the body; and, therefore, +that any general development of the various +other "faculties" have presumably entailed a collateral +development of the two in question.</p> + +<p>Again, in the second place, it would seem that<span class="pagenum"><a name="Page_30" id="Page_30">[Pg 30]</a></span> +Mr. Wallace has not sufficiently considered the co-operation +of either well-known natural causes, which +must have materially assisted the survival of the +fittest where these two "faculties" are concerned. +For, even if we disregard the inherited effects of +use—which, however, if entertained as possible in any +degree at all, must have here constituted an important +factor,—there remain on the one hand, the unquestionable +influences of individual education and, +on the other hand, of the selection principle operating +in the mind itself.</p> + +<p>Taking these two points separately, it is surely +sufficiently well known that individual education—or +special training, whether of mind or body—usually +raises congenital powers of any kind to a more +or less considerable level above those of the normal +type. In other words, whatever doubt there may be +touching the <i>inherited</i> effects of use, there can be no +question touching the immense <i>developmental</i> effects +thereof in the individual life-time. Now, the conditions +of savage life are not such as lead to any deliberate +cultivation of the "faculties" either of the mathematical +or aesthetic order. Consequently, as might be expected, +we find both of them in what Mr. Wallace +regards as but a "latent" stage of development. But +in just the same way do we find that the marvellous +powers of an acrobat when specially trained from childhood—say +to curve his spine backwards until his teeth +can bite his heels—are "latent" in all men. Or, more +correctly, they are <i>potential in every child</i>. So it is +with the prodigious muscular development of a trained +athlete, and with any number of other cases where +either the body or the mind is concerned. Why then<span class="pagenum"><a name="Page_31" id="Page_31">[Pg 31]</a></span> +should Mr. Wallace select the particular instances of +the mathematical and aesthetic powers in savages as in +any special sense "prophetic" of future development +in trained members of civilized races? Although it +is true that these "latent capacities and powers are +unused by savages," is it not equally true that savages +fail to use their latent capacities and powers as +tumblers and athletes? Moreover, is it not likewise +true that <i>as</i> used by savages, or as occurring normally +in man, such capacities and powers are no less poorly +developed than are those of the "faculties" on which +Mr. Wallace lays so much stress? In other words, +are not "latent capacities and powers" of all kinds +more or less equally in excess of anything that is ever +required of them by man in a state of nature? Therefore, +if we say that where mathematics and the fine +arts are concerned the potential capacities of savage +man are in some mystical sense "prophetic" of +a Newton or a Beethoven, so in consistency ought we +to say that in these same capacities we discern a +similar prophecy of those other uses of civilized life +which we have in a rope-dancer or a clown.</p> + +<p>Again, and in addition to this, it should be remembered +that, even if we do suppose any prophecy of +this kind where the particular capacities in question +are concerned, we must clearly extend the reference to +the lower animals. Not a few birds display aesthetic +feelings in a measure fairly comparable with those of +savages; while we know that some animals present +the germs of a "faculty" of computation<a name="FNanchor_21_21" id="FNanchor_21_21"></a><a href="#Footnote_21_21" class="fnanchor">[21]</a>. But, it is<span class="pagenum"><a name="Page_32" id="Page_32">[Pg 32]</a></span> +needless to add, this fact is fatal to Mr. Wallace's +argument as I understand it——viz. that the "faculties" +in question have been in some special manner communicated +by some superior intelligence to <i>man</i>.</p> + +<p>Once more, it is obviously unfair to select such men as +a "Newton, a La Place, a Gauss, or a Cayley" for the +purpose of estimating the difference between savages +and civilized man in regard to the latter "faculty." +These men are the picked mathematicians of centuries. +Therefore they are men who not only enjoyed all +the highest possible benefits of individual culture, but +likewise those who have been most endowed with +mathematical power congenitally. So to speak, they +are the best variations in this particular direction +which our race is known to have produced. But +had such variations arisen among savages it is +sufficiently obvious that they could have come to +nothing. Therefore, it is the <i>normal average</i> of +"mathematical faculty" in civilized man that should +be contrasted with that of savage man; and, when +due regard is paid to the all-important consideration +which immediately follows, I cannot feel that the +contrast presents any difficulty to the theory of human +evolution by natural causation.</p> + +<p>Lastly, the consideration just alluded to is, that +civilized man enjoys an advantage over savage man +far in advance even of those which arise from a settled +state of society, incentives to intellectual training, +and so on. This inestimable advantage consists in +the art of writing, <i>and the consequent transmission<span class="pagenum"><a name="Page_33" id="Page_33">[Pg 33]</a></span> +of the effects of culture from generation to generation</i>. +Quite apart from any question as to the hereditary +transmission of acquired characters, we have in this +<i>intellectual</i> transmission of acquired <i>experience</i> a +means of accumulative cultivation quite beyond our +powers to estimate. For, unlike all other cases where +we recognize the great influence of individual use or +practice in augmenting congenital "faculties" (such +as in the athlete, pianist, &c.), in this case the effects of +special cultivation do not end with the individual life, +but are carried on and on through successive generations +<i>ad infinitum</i>. Hence, a civilized man inherits +mentally, if not physically, the effects of culture for +ages past, and this in whatever direction he may choose +to profit therefrom. Moreover—and I deem this +an immensely important addition—in this unique +department of purely intellectual transmission, a +kind of non-physical natural selection is perpetually +engaged in producing the best results. For here +a struggle for existence is constantly taking place +among "ideas," "methods," and so forth, in what +may be termed a psychological environment. The +less fit are superseded by the more fit, and this not +only in the mind of the individual, but, through language +and literature, still more in the mind of the race. +"A Newton, a La Place, a Gauss, or a Cayley," +would all alike have been impossible, but for a previously +prolonged course of mental evolution due to the +selection principle operating in the region of mathematics, +by means of continuous survivals of the best +products in successive generations. And, of course, +the same remark applies to art in all its branches<a name="FNanchor_22_22" id="FNanchor_22_22"></a><a href="#Footnote_22_22" class="fnanchor">[22]</a>.</p> +<p><span class="pagenum"><a name="Page_34" id="Page_34">[Pg 34]</a></span></p> +<p>Quitting then the last, and in my opinion the +weakest chapter of <i>Darwinism</i>, the most important +points presented by other portions of this work are—to +quote its author's own enumeration of them—an +attempted "proof that all specific characters are (or +once have been) either useful in themselves or correlated +with useful characters": an attempted "proof +that natural selection can, in certain cases, increase +the sterility of crosses": an attempted "proof that +the effects of use and disuse, even if inherited, must be +overpowered by natural selection": an attempted +proof that the facts of variation in nature are in themselves +sufficient to meet the difficulty which arises +against the theory of natural selection, as held by him, +from the swamping effects of free <span class="correction" title="Transcriber's Note: 'inter-crossing' in the text.">intercrossing</span>: and, +lastly, "a fuller discussion on the colour relations of +animals, with additional facts and arguments on the +origin of sexual differences of colour." As I intend to +deal with all these points hereafter, excepting the last, +it will be sufficient in this opening chapter to remark, +that in as far as I disagree with Mr. Wallace (and +agree with Darwin), on the subject of "sexual +differences of colour," my reasons for doing so have +been already sufficiently stated in Part I. But there +is much else in his treatment of this subject which +appears to me highly valuable, and therefore presenting +an admirable contribution to the literature of +Darwinism. In particular, it appears to me that the +most important of his views in this connexion<span class="pagenum"><a name="Page_35" id="Page_35">[Pg 35]</a></span> +probably represents the truth—namely, that, among +the higher animals, more or less conspicuous peculiarities +of colour have often been acquired for the +purpose of enabling members of the same species +quickly and certainly to recognize one another. +This theory was first published by Mr. J. E. Todd, +in 1888, and therefore but a short time before its +re-publication by Mr. Wallace. As his part in the +matter has not been sufficiently recognized, I should +like to conclude this introductory chapter by drawing +prominent attention to the merits of Mr. Todd's +paper. For not only has it the merit of priority, but +it deals with the whole subject of "recognition +colours"—or, as he calls them, "directive colours"—in +a more comprehensive manner than has been done +by any of his successors. In particular, he shows +that the principle of recognition-marking is not restricted +to facilitating sexual intercourse, but extends +also to several other matters of importance in the +economy of animal life<a name="FNanchor_23_23" id="FNanchor_23_23"></a><a href="#Footnote_23_23" class="fnanchor">[23]</a>.</p> + +<hr class="tb" /> + +<p>Having thus briefly sketched the doctrines of the +sundry Post-Darwinian Schools from a general point +of view, I shall endeavour throughout the rest of this +treatise to discuss in appropriate detail the questions +which have more specially come to the front in the +post-Darwinian period. It can scarcely be said that +any one of these questions has arisen altogether <i>de +novo</i> during this period; for glimmerings, more or +less conspicuous, of all are to be met with in the +writings of Darwin himself. Nevertheless it is no +less true that only after his death have they been<span class="pagenum"><a name="Page_36" id="Page_36">[Pg 36]</a></span> +lighted up to the full blaze of active discussion<a name="FNanchor_24_24" id="FNanchor_24_24"></a><a href="#Footnote_24_24" class="fnanchor">[24]</a>. By +far the most important of them are those to which +the rest of this treatise will be confined. They are +four in number, and it is noteworthy that they are all +intimately connected with the great question which +Darwin spent the best years of his life in contemplating, +and which has therefore, in one form or +another, occupied the whole of the present chapter—the +question as to whether natural selection has been +the sole cause, or but the chief cause of modification.</p> + +<p>The four questions above alluded to appertain +respectively to Heredity, Utility, Isolation, and Physiological +Selection. Of these the first two will form +the subject-matter of the present volume, while the +last two will be dealt with in the final instalment of +<i>Darwin, and after Darwin</i>.</p> + +<hr class="full" /> +<p class="pagenum"><a name="Page_37" id="Page_37">[Pg 37]</a></p> + + + + +<h2>SECTION I<br /> +<i>HEREDITY</i></h2> +<hr class="chap" /> +<p class="pagenum"><a name="Page_39" id="Page_39">[Pg 39]</a></p> + + + + +<h2>CHAPTER II.<br /> +<span class="smcap">Characters As Hereditary and Acquired<br /> +(Preliminary).</span></h2> + +<p>We will proceed to consider, throughout Section I +of the present work, the most important among those +sundry questions which have come to the front +since the death of Darwin. For it was in the year +after this event that Weismann published the first +of his numerous essays on the subject of Heredity, +and, unquestionably, it has been these essays which +have given such prominence to this subject during +the last decade.</p> + +<p>At the outset it is desirable to be clear upon +certain points touching the history of the subject; +the limits within which our discussion is to be confined; +the relation in which the present essay stands +to the one that I published last year under the +title <i>An Examination of Weismannism</i>; and several +other matters of a preliminary kind.</p> + +<p>The problems presented by the phenomena of +heredity are manifold; but chief among them is +the hitherto unanswered question as to the transmission +or non-transmission of acquired characters. +This is the question to which the present Section +will be confined.</p> + +<p>Although it is usually supposed that this question<span class="pagenum"><a name="Page_40" id="Page_40">[Pg 40]</a></span> +was first raised by Weismann, such was not the case. +Any attentive reader of the successive editions of +Darwin's works may perceive that at least from the +year 1859 he had the question clearly before his +mind; and that during the rest of his life his +opinion with regard to it underwent considerable +modifications—becoming more and more Lamarckian +the longer that he pondered it. But it was not till +1875 that the question was clearly presented to +the general public by the independent thought of +Mr. Galton, who was led to challenge the Lamarckian +factors <i>in toto</i> by way of deduction from his +theory of Stirp—the close resemblance of which to +Professor Weismann's theory of Germ-plasm has +been shown in my <i>Examination of Weismannism</i>. +Lastly, I was myself led to doubt the Lamarckian +factors still further back in the seventies, +by having found a reason for questioning the main +evidence which Mr. Darwin had adduced in their +favour. This doubt was greatly strengthened on +reading, in the following year, Mr. Galton's <i>Theory +of Heredity</i> just alluded to; and thereupon I commenced +a prolonged course of experiments upon the +subject, the general nature of which will be stated +in future chapters. Presumably many other persons +must have entertained similar misgivings touching the +inheritance of acquired characters long before the +publication of Weismann's first essay upon the subject +in 1883. The question as to the inheritance of +acquired characters was therefore certainly not first +raised by Weismann—although, of course, there is +no doubt that it was conceived by him independently, +and that he had the great merit of calling general<span class="pagenum"><a name="Page_41" id="Page_41">[Pg 41]</a></span> +attention to its existence and importance. On the +other hand, it cannot be said that he has succeeded in +doing very much towards its solution. It is for these +reasons that any attempt at dealing with Weismann's +fundamental postulate—i.e. that of the non-inheritance +of acquired characters—was excluded from my +<i>Examination of Weismannism</i>. As there stated, he is +justified in assuming, for the purposes of his discussion, +a negative answer to the question of such inheritance; +but evidently the question itself ought not to be included +within what we may properly understand by +"Weismannism." Weismannism, properly so called, +is an elaborate system of theories based on the fundamental +postulate just mentioned—theories having +reference to the mechanism of heredity on the one hand, +and to the course of organic evolution on the other. +Now it was the object of the foregoing <i>Examination</i> to +deal with this system of theories <i>per se</i>; and therefore +we have here to take a new point of departure and +to consider separately the question of fact as to the +inheritance or non-inheritance of acquired characters. +At first sight, no doubt, it will appear that in adopting +this method I am putting the cart before the horse. +For it may well appear that I ought first to have +dealt with the validity of Weismann's postulate, and +not till then to have considered the system of theories +which he has raised upon it. But this criticism is +not likely to be urged by any one who is well acquainted +with the questions at issue. For, in the first +place, it is notorious that the question of fact is +still open to question; and therefore it ought to be +considered separately, or apart from any theories +which may have been formed with regard to it. In<span class="pagenum"><a name="Page_42" id="Page_42">[Pg 42]</a></span> +the second place, our judgement upon this question +of fact must be largely influenced by the validity of +general reasonings, such as those put forward in the +interests of rival theories of heredity; and, as the +theory of germ-plasm has been so thoughtfully +elaborated by Professor Weismann, I have sought to +give it the attention which it deserves as preliminary +to our discussion of the question of fact which now lies +before us. Thirdly and lastly, even if this question +could be definitely answered by proving either that +acquired characters are inherited or that they are not, +it would by no means follow that Weismann's theory +of heredity would be proved wholly false in the one +case, or wholly true in the other. That it need not +be wholly true, even were its fundamental postulate to +be proved so, is evident, because, although the fact +might be taken to prove the theory of Continuity, the +theory of Germ-plasm is, as above stated, very much +more than this. That the theory of Germ-plasm +need not be wholly false, even if acquired characters +should ever be proved heritable, a little thought may +easily show, because, in this event, the further question +would immediately arise as to the degrees and the +comparative frequency of such inheritance. For my +own part, as stated in the <i>Examination</i>, I have always +been disposed to accept Mr. Galton's theory of Stirp +in preference to that of Germ-plasm on this very +ground—i. e. that it does not dogmatically exclude the +possibility of an occasional inheritance of acquired +characters in faint though cumulative degrees. And +whatever our individual opinions may be touching the +admissibility of such a <i>via media</i> between the theories +of Pangenesis and Germ-plasm, at least we may all<span class="pagenum"><a name="Page_43" id="Page_43">[Pg 43]</a></span> +agree on the desirability of fully considering the +matter as a preliminary to the discussion of the +question of fact.</p> + +<p>As it is not to be expected that even those who +may have read my previous essay can now carry all +these points in their memories, I will here re-state +them in a somewhat fuller form.</p> + +<p>The following diagram will serve to give a clearer +view of the sundry parts of Professor Weismann's +system of theories, as well as of their relations to one +another.</p> + +<div class="figcenter" style="width: 218px;"> +<img src="images/illus_055.png" width="218" height="331" alt="Postulate as to the absolute non-inheritance of acquired characters." title="Postulate as to the absolute non-inheritance of acquired characters." /> +<span class="caption">Postulate as to the absolute non-inheritance of acquired characters.</span></div> + +<p>Now, as just explained, the parts of this system +which may be properly and distinctively called +"Weismannism" are those which go to form the +Y-like structure of deductions from the fundamental +postulate. Therefore, it was the Y-like system of<span class="pagenum"><a name="Page_44" id="Page_44">[Pg 44]</a></span> +deductions which were dealt with in the <i>Examination +of Weismannism</i>, while it is only his basal postulate +which has to be dealt with in the following chapters.</p> + +<p>So much, then, for the relations of Weismann's +system of theories to one another. It is, however, of +even more importance that we should gain a clear +view of the relations between his theory of <i>heredity</i> +to those of Darwin and of Galton, as preliminary to +considering the fundamental question of fact.</p> + +<p>As we have already seen, the theory of germ-plasm +is not only a theory of heredity: it is also, and more +distinctively, a theory of evolution, &c. As a theory +of heredity it is grounded on its author's fundamental +postulate—the <i>continuity</i> of germ-plasm. But as a +theory of evolution, it requires for its support this +additional postulate, that the continuity of germ-plasm +has been <i>absolute</i> "since the first origin of +life." It is clear that this additional postulate is not +needed for his theory of heredity, but only for his +additional theory of evolution, &c. There have been +one or two other theories of heredity, prior to this one, +which, like it, have been founded on the postulate of +Continuity of the substance of heredity; but it has +not been needful for any of these theories to postulate +further that this substance has been <i>always</i> thus +isolated, or even that it is now <i>invariably</i> so. For +even though the isolation be frequently invaded by +influences of body-changes on the congenital characters +of this substance, it does not follow that this principle +of Continuity may not still be true <i>in the main</i>, even +although it is supplemented in some degree by that +of use-inheritance. Indeed, so far as the phenomena +of heredity are concerned, it is conceivable that<span class="pagenum"><a name="Page_45" id="Page_45">[Pg 45]</a></span> +all congenital characters were originally acquired, +and afterwards became congenital on account of their +long inheritance. I do not myself advocate this view +as biologically probable, but merely state it as logically +possible, and in order to show that, so far as the +phenomena of heredity are concerned, there appears +to be no reason for Weismann's deduction that the +principle of Continuity, if true at all, must be <i>absolute</i>. +And it would further appear, the only reason why he +makes this deduction (stem of the Y) is in order to +provide a foundation for his further theories of evolution, +&c. (arms of the Y). It is indeed necessary for +these further theories that body-changes should +never exercise any hereditary influence on the hereditary +endowments of germ-plasm, and therefore it is +that he posits the substance of heredity as, not only +continuous, but uninterruptably so "since the first +origin of life."</p> + +<p>Now, this may be made more clear by briefly comparing +Weismann's theory with those of Darwin and +of Galton. Weismann's theory of heredity, then, +agrees with its predecessors which we are considering +in all the following respects. The substance of heredity +is particulate; is mainly lodged in highly specialized +cells; is nevertheless also distributed <span class="correction" title="Transcriber's Note: 'thoughout' in the text.">throughout</span> the +general cellular tissues, where it is concerned in all +processes of regeneration, repair, and a-sexual reproduction; +presents an enormously complex structure, +in that every constituent part of a potentially future +organism is represented in a fertilized ovum by corresponding +particles; is everywhere capable of virtually +unlimited multiplication, without ever losing its hereditary +endowments; is often capable of carrying<span class="pagenum"><a name="Page_46" id="Page_46">[Pg 46]</a></span> +these endowments in a dormant state through a long +series of generations until at last they <span class="correction" title="Transcriber's Note: 're-appear' in the text.">reappear</span> +in what we recognize as recursions. Thus far all +three theories are in agreement. In fact, the only +matter of any great importance wherein they disagree +has reference to the doctrine of Continuity<a name="FNanchor_25_25" id="FNanchor_25_25"></a><a href="#Footnote_25_25" class="fnanchor">[25]</a>. For +while Darwin's theory supposes the substance of +heredity to be mainly formed anew in each ontogeny, +and therefore that the continuity of this substance is +for the most part interrupted in every generation<a name="FNanchor_26_26" id="FNanchor_26_26"></a><a href="#Footnote_26_26" class="fnanchor">[26]</a>, +Weismann's theory supposes this substance to be +formed only during the phylogeny of each species, +and therefore to have been absolutely uninterrupted +since the first origin of life.</p> + +<p>But now, Galton's theory of heredity stands much +nearer to Weismann's in this matter of Continuity; +for it is, as he says, a theory of "modified pangenesis," +and the modification consists in allowing very much +more for the principle of Continuity than is allowed +by Darwin's theory; in fact he expresses himself as +quite willing to adopt (on adequate grounds being +shown) the doctrine of Continuity as absolute, and +therefore propounded, as logically possible, the identical +theory which was afterwards and independently +announced by Weismann. Or, to quote his own +words—</p> + +<blockquote><p>"We might almost reserve our belief that the structural [i. e. +somatic] cells can react on the sexual elements at all, and we<span class="pagenum"><a name="Page_47" id="Page_47">[Pg 47]</a></span> +may be confident that at most they do so in a very faint degree; +in other words, that acquired modifications are barely, if at all, +<i>inherited</i>, in the correct sense of that word<a name="FNanchor_27_27" id="FNanchor_27_27"></a><a href="#Footnote_27_27" class="fnanchor">[27]</a>."</p></blockquote> + +<p>So far Mr. Galton; but for Weismann's further +theory of evolution, &c., it is necessary to postulate +the additional doctrine in question; and it makes +a literally immeasurable difference to any theory of +evolution whether or not we entertain this additional +postulate. For no matter how faintly or how fitfully +the substance of heredity may be modified by somatic +tissues, the Lamarckian principles are hypothetically +allowed some degree of play. And although this is +a lower degree than Darwin supposed, their influence +in determining the course of organic evolution may +still have been enormous; seeing that their action in +any degree must always have been <i>directive</i> of variation +on the one hand, and <i>cumulative</i> on the other.</p> + +<p>Thus, by merely laying this theory side by side +with Weismann's we can perceive at a glance how +a <i>pure</i> theory of <i>heredity</i> admits of being based +on the postulate of Continuity alone, without cumbering +itself by any further postulate as to this +Continuity being <i>absolute</i>. And this, in my opinion +is the truly scientific attitude of mind for us to adopt +as preliminary to the following investigation. For +the whole investigation will be concerned—and concerned +only—with this question of Continuity as absolute, +or as admitting of degrees. There is, without +any question, abundant evidence to prove that the +substance of heredity is at least partly continuous +(Gemmules). It may be that there is also abundant +evidence to prove this substance much more <i>largely</i><span class="pagenum"><a name="Page_48" id="Page_48">[Pg 48]</a></span> +continuous than Darwin supposed (Stirp); but be this +as it may, it is certain that any such question as to +the <i>degree</i> of continuity differs, <i>toto caelo</i>, from that as +to whether there can ever be any continuity at all.</p> + +<p>How, then, we may well ask, is it that so able +a naturalist and so clear a thinker as Weismann +can have so far departed from the inductive methods +as to have not merely propounded the question +touching Continuity and its degrees, or even of Continuity +as absolute; but to have straightway assumed +the latter possibility as a basis on which to run +a system of branching and ever-changing speculations +concerning evolution, variation, the ultimate structure +of living material, the intimate mechanism of +heredity, or, in short, such a system of deductive +conjectures as has never been approached in the +history of science? The answer to this question is +surely not far to seek. Must it not be the answer +already given? Must it not have been for the sake +of rearing this enormous structure of speculation +that Weismann has adopted the assumption of +Continuity as absolute? As we have just seen, +Galton had well shown how a theory of heredity +could be founded on the general doctrine of Continuity, +without anywhere departing from the inductive +methods—even while fully recognizing the +possibility of such continuity as absolute. But +Galton's theory was a "<i>Theory of Heredity</i>," and +nothing more. Therefore, while clearly perceiving +that the Continuity in question <i>may</i> be absolute, +he saw no reason, either in fact or in theory, for +concluding that it <i>must</i> be. On the contrary, he +saw that this question is, for the present, necessarily<span class="pagenum"><a name="Page_49" id="Page_49">[Pg 49]</a></span> +unripe for profitable discussion—and, <i>a fortiori</i>, for +the shedding of clouds of seed in all the directions +of "Weismannism."</p> + +<p>Hence, what I desire to be borne in mind throughout +the following discussion is, that it will have +exclusive reference to the question of fact already +stated, without regard to any superjacent theories; +and, still more, that there is a vast distinction +between any question touching the degrees in which +acquired characters are transmitted to progeny, and +the question as to whether they are ever transmitted +in any degree at all. Now, the latter question, +being of much greater importance than the former, +is the one which will mainly occupy our attention +throughout the rest of this Section.</p> + +<p>We have already seen that before the subject was +taken up by Weismann the difference between acquired +and congenital characters in respect to transmissibility +was generally taken to be one of degree; not one of +kind. It was usually supposed that acquired characters, +although not so fully and not so certainly +inherited as congenital characters, nevertheless were +inherited in some lesser degree; so that if the same +acquired character continued to be successively acquired +in a number of sequent generations, what was +at first only a slight tendency to be inherited would +become by summation a more and more pronounced +tendency, till eventually the acquired character might +become as strongly inherited as a congenital one. +Or, more precisely, it was supposed that an acquired +character, in virtue of such a summation of hereditary +influence, would in time become congenital. Now, +if this supposition be true, it is evident that more or<span class="pagenum"><a name="Page_50" id="Page_50">[Pg 50]</a></span> +less assistance must be lent to natural selection in +its work of evolving adaptive modifications<a name="FNanchor_28_28" id="FNanchor_28_28"></a><a href="#Footnote_28_28" class="fnanchor">[28]</a>. And +inasmuch as we know to what a wonderful extent +adaptive modifications are secured during individual +life-times—by the direct action of the environment on +the one hand, and by increased or diminished use of +special organs and mental faculties on the other—it +becomes obvious of what importance even a small +measure of transmissibility on their part would be +in furnishing to natural selection ready-made variations +in required directions, as distinguished from +promiscuous variations in all directions. Contrariwise, +if functionally-produced adaptations and adaptations +produced by the direct action of the environment +are never transmitted in any degree, not only<span class="pagenum"><a name="Page_51" id="Page_51">[Pg 51]</a></span> +would there be an incalculable waste, so to speak, of +adaptive modifications—these being all laboriously +and often most delicately built up during life-times of +individuals only to be thrown down again as regards +the interest of species—but so large an additional +burden would be thrown upon the shoulders of natural +selection that it becomes difficult to conceive how +even this gigantic principle could sustain it, as I shall +endeavour to show more fully in future chapters. On +the other hand, however, Weismann and his followers +not only feel no difficulty in throwing overboard all +this ready-made machinery for turning out adaptive +modifications when and as required; but they even +represent that by so doing they are following the +logical maxim, <i>Entia non sunt multiplicanda praeter +necessitatem</i>—which means, in its relation to causality, +that we must not needlessly multiply hypothetical +principles to explain given results. But when appeal +is here made to this logical principle—the so-called +Law of Parsimony—two things are forgotten.</p> + +<p>In the first place, it is forgotten that the very +question in debate is whether causes of the Lamarckian +order <i>are</i> unnecessary to explain all the phenomena +of organic nature. Of course if it could be +proved that the theory of natural selection alone +is competent to explain all these phenomena, appeal +to the logical principle in question would be justifiable. +But this is precisely the point which the +followers of Darwin refuse to accept; and so long as +it remains the very point at issue, it is a mere begging +the question to represent that a class of causes which +have hitherto been regarded as necessary are, in +fact, unnecessary. Or, in other words, when Darwin<span class="pagenum"><a name="Page_52" id="Page_52">[Pg 52]</a></span> +himself so decidedly held that these causes are necessary +as supplements to natural selection, the burden +of proof is quite as much on the side of Weismann +and his followers to show that Darwin's opinion +was wrong, as it is on the side of Darwin's followers +to show that it was right. Yet, notwithstanding the +elaborate structure of theory which Weismann has +raised, there is nowhere one single fact or one single +consideration of much importance to the question +in debate which was not perfectly well known to +Darwin. Therefore I say that all this challenging +of Darwinists to justify their "Lamarckian assumptions" +really amounts to nothing more than a pitting +of opinion against opinion, where there is at least as +much call for justification on the one side as on the +other.</p> + +<p>Again, when these challenges are thrown down by +Weismann and his followers, it appears to be forgotten +that the conditions of their own theory are such as +to render acceptance of the gauge a matter of great +difficulty. The case is very much like that of a +doughty knight pitching his glove into the sea, and +then defying any antagonist to take it up. That this +is the case a very little explanation will suffice to +show.</p> + +<p>The question to be settled is whether acquired +characters are ever transmitted by heredity. Now +suppose, for the sake of argument, that acquired +characters are transmitted by heredity—though not so +fully and not so certainly as congenital characters—how +is this fact to be proved to the satisfaction of +Weismann and his followers? First of all they +answer,—Assuredly by adducing experimental proof<span class="pagenum"><a name="Page_53" id="Page_53">[Pg 53]</a></span> +of the inheritance of injuries, or mutilations. But +in making this answer they appear to forget that +Darwin has already shown its inefficiency. That the +self-styled Neo-Lamarckians have been much more +unguarded in this respect, I fully admit; but it is +obviously unfair to identify Darwin's views with those +of a small section of evolutionists, who are really as +much opposed to Darwin's teaching on one side as is +the school of Weismann on the other. Yet, on reading +the essays of Weismann himself—and still more +those of his followers—one would almost be led to +gather that it is claimed by him to have enunciated +the distinction between congenital and acquired characters +in respect of transmissibility; and therefore +also to have first raised the objection which lies +against the theory of Pangenesis in respect of the +non-transmissibility of mutilations. In point of fact, +however, Darwin is as clear and decided on these +points as Weismann. And his answer to the obvious +difficulty touching the non-transmissibility of mutilations +is, to quote his own words, "the long-continued +inheritance of a part which has been removed during +many generations is no real anomaly, for gemmules +formerly derived from the part are multiplied and +transmitted from generation to generation<a name="FNanchor_29_29" id="FNanchor_29_29"></a><a href="#Footnote_29_29" class="fnanchor">[29]</a>." Therefore, +so far as Darwin's theory is concerned, the +challenge to produce evidence of the transmission of +injuries is irrelevant: it is no more a part of Darwin's +theory than it is of Weismann's to maintain that +injuries <i>are</i> transmitted.</p> + +<p>There is, however, one point in this connexion to +which allusion must here be made. Although Darwin<span class="pagenum"><a name="Page_54" id="Page_54">[Pg 54]</a></span> +did not believe in the transmissibility of mutilations +when these consist merely in the amputation of parts +of an organism, he did believe in a probable tendency +to transmission when removal of the part is followed +by gangrene. For, as he says, in that case, all the +gemmules of the mutilated or amputated part, as they +are gradually attracted to that part (in accordance +with the law of affinity which the theory assumes), +will be successively destroyed by the morbid process. +Now it is of importance to note that Darwin made +this exception to the general rule of the non-transmissibility +of mutilations, not because his theory of +pangenesis required it, but because there appeared to +be certain very definite observations and experiments—which +will be mentioned later on—proving that +when mutilations are followed by gangrene they are +apt to be inherited: his object, therefore, was to +reconcile these alleged facts with his theory, quite as +much as to sustain his theory by such facts.</p> + +<p>So much, then, for the challenge to produce +direct evidence of the transmissibility of acquired +characters, so far as mutilations are concerned: +believers in Darwin's theory, as distinguished from +Weismann's, are under no obligation to take up such +a challenge. But the challenge does not end here. +Show us, say the school of Weismann, a single instance +where an acquired character <i>of any kind</i> (be it +a mutilation or otherwise) has been inherited: this is +all that we require: this is all that we wait for: and +surely, unless it be acknowledged that the Lamarckian +doctrine reposes on mere assumption, at least one +such case ought to be forthcoming. Well, nothing +can sound more reasonable than this in the first instance;<span class="pagenum"><a name="Page_55" id="Page_55">[Pg 55]</a></span> +but as soon as we begin to cast about for +cases which will satisfy the Neo-Darwinians, we find +that the structure of their theory is such as to preclude, +in almost every conceivable instance, the possibility +of meeting their demand. For their theory begins +by assuming that natural selection is the one and only +cause of organic evolution. Consequently, what their +demand amounts to is throwing upon the other side +the burden of disproving this assumption—or, in other +words, of proving the negative that in any given case of +transmitted adaptation natural selection has <i>not</i> been +the sole agent at work. Now, it must obviously be +in almost all cases impossible to prove this negative +among species in a state of nature. For, even supposing +that among such species Lamarckian principles +have had a large share in the formation of +hereditary and adaptive characters, how would Weismann +himself propose that we should set about the +proof of such a fact, where the proof demanded by his +assumption is, that the <i>abstract possibility</i> of natural +selection having had anything to do with the matter +must be excluded? Obviously this is impossible in +the case of inherited characters which are also +<i>adaptive</i> characters. How then does it fare with the +case of inherited characters which are not also +adaptive? Merely that this case is met by another +and sequent assumption, which constitutes an integral +part of the Neo-Darwinian creed—namely, that in +nature there <i>can be no such characters</i>. Seeing that +natural selection is taken to be the only possible +cause of change in species, it follows that all changes +occurring in species must necessarily be adaptive, +whether or not we are able to perceive the adaptations.<span class="pagenum"><a name="Page_56" id="Page_56">[Pg 56]</a></span> +In this way apparently useless characters, as well as +obviously useful ones, are ruled out of the question: +that is to say, <i>all</i> hereditary characters of species in +a state of nature are <i>assumed</i> to be due to natural +selection, and then it is demanded that the validity of +this assumption should be disproved by anybody who +doubts it. Yet Weismann himself would be unable +to suggest any conceivable method by which it can +be disproved among species in a state of nature—and +this even supposing that the assumption is entirely +false<a name="FNanchor_30_30" id="FNanchor_30_30"></a><a href="#Footnote_30_30" class="fnanchor">[30]</a>.</p> + +<p>Consequently, the only way in which these +speciously-sounding challenges can be adequately met +is by removing some individuals of a species from +a state of nature, and so from all known influences +of natural selection; then, while carefully avoiding +artificial selection, causing these individuals and their +progeny through many generations unduly to exercise +some parts of their bodies, or unduly to fail in +the exercise of others. But, clearly, such an experiment +is one that must take years to perform, and +therefore it is now too early in the day to reproach +the followers of Darwin with not having met the +challenges which are thrown down by the followers +of Weismann<a name="FNanchor_31_31" id="FNanchor_31_31"></a><a href="#Footnote_31_31" class="fnanchor">[31]</a>.</p> +<p><span class="pagenum"><a name="Page_57" id="Page_57">[Pg 57]</a></span></p> +<p>Probably enough has now been said to show that +the Neo-Darwinian assumption precludes the possibility +of its own disproof from any of the facts of +nature (as distinguished from domestication)—and +this even supposing that the assumption be false. On +the other hand, of course, it equally precludes the +possibility of its own proof; and therefore it is as +idle in Darwinists to challenge Weismann for proof of +his negative (i. e. that acquired characters are not transmitted), +as it is in Weismann to challenge Darwinists +for proof of the opposite negative (i. e. that all +seeming cases of such transmission are not due to +natural selection). This dead-lock arises from the +fact that in nature it is beyond the power of the +followers of Darwin to exclude the abstract possibility +of natural selection in any given case, while it is +equally beyond the power of the followers of Weismann +to exclude the abstract possibility of Lamarckian +principles. Therefore at present the question must +remain for the most part a matter of opinion, based +upon general reasoning as distinguished from special +facts or crucial experiments. The evidence available +on either side is presumptive, not demonstrative<a name="FNanchor_32_32" id="FNanchor_32_32"></a><a href="#Footnote_32_32" class="fnanchor">[32]</a>. +But it is to be hoped that in the future, when time +shall have been allowed for the performance of definite +experiments on a number of generations of domesticated +plants or animals, intentionally shielded from +the influences of natural selection while exposed to +those of the Lamarckian principles, results will be<span class="pagenum"><a name="Page_58" id="Page_58">[Pg 58]</a></span> +gained which will finally settle the question one +way or the other.</p> + +<p>Meanwhile, however, we must be content with the +evidence as it stands; and this will lead us to the +second division of our subject. That is to say, having +now dealt with the antecedent, or merely logical, +state of the question, we have next to consider what +actual, or biological, evidence there is at present +available on either side of it. Thus far, neither side +in the debate has any advantage over the other. On +grounds of general reasoning alone they both have +to rely on more or less dogmatic assumptions. For +it is equally an unreasoned statement of opinion +whether we allege that all the phenomena of organic +evolution can be, or can not be, explained by the +theory of natural selection alone. We are at present +much too ignorant touching the causes of organic +evolution to indulge in dogmatism of this kind; +and if the question is to be referred for its answer +to authority, it would appear that, both in respect +of number and weight, opinions on the side of having +provisionally to retain the Lamarckian factors are +more authoritative than those <i>per contra</i><a name="FNanchor_33_33" id="FNanchor_33_33"></a><a href="#Footnote_33_33" class="fnanchor">[33]</a>.</p> + +<hr class="tb" /> + +<p>Turning then to the question of fact, with which +the following chapters are concerned, I will conclude +this preliminary one with a few words on the method +of discussion to be adopted.</p> + +<p>First I will give the evidence in favour of Lamarckianism; +this will occupy the next two chapters.<span class="pagenum"><a name="Page_59" id="Page_59">[Pg 59]</a></span> +Then, in Chapter V, I will similarly give the evidence +<i>per contra</i>, or in favour of Continuity as absolute. +Lastly, I will sum up the evidence on both sides, +and give my own judgement on the whole case. But +on whichever side I am thus acting as special pleader +for the time being, I will adduce only such arguments +as seem to me valid—excluding alike from both the +many irrelevant or otherwise invalid reasonings which +have been but too abundantly published. Moreover, +I think it will be convenient to consider all that has +been said—or may be said—in the way of criticism +to each argument by the opposite side while such +argument is under discussion—i. e. not to wait till +all the special pleading on one side shall have been +exhausted before considering the exceptions which +have been (or admit of being) taken to the arguments +adduced, but to deal with such exceptions at the time +when each of these arguments shall have been severally +stated. Again, and lastly, I will arrange the evidence +in each case—i. e. on both sides—under three +headings, viz. (A) Indirect, (B) Direct, and (C) Experimental<a name="FNanchor_34_34" id="FNanchor_34_34"></a><a href="#Footnote_34_34" class="fnanchor">[34]</a>. +]</p> + + + + +<hr class="chap" /> +<p class="pagenum"><a name="Page_60" id="Page_60">[Pg 60]</a></p> +<h2>CHAPTER III.<br /> +<span class="smcap">Characters as Hereditary and Acquired</span><br /> +(<i>continued</i>).</h2> + + +<h3>(A.)<br /> +<i>Indirect Evidence in favour of the Inheritance +of Acquired Characters.</i></h3> + +<p>Starting with the evidence in favour of the so-called +Lamarckian factors, we have to begin with the +Indirect—and this without any special reference to +the theories, either of Weismann or of others.</p> + +<p>It has already been shown, while setting forth in +the preceding chapter the antecedent standing of the +issue, that in this respect the <i>prima facie</i> presumption +is wholly on the side of the transmission, in +greater degree or less, of acquired characters. Even +Weismann allows that all "<i>appearances</i>" point in +this direction, while there is no inductive evidence +of the action of natural selection in any one case, +either as regards germs or somas, and therefore, +<i>a fortiori</i>, of the "all-sufficiency" of this cause<a name="FNanchor_35_35" id="FNanchor_35_35"></a><a href="#Footnote_35_35" class="fnanchor">[35]</a>. It +is true that in some of his earlier essays he has +argued that there is no small weight of <i>prima facie</i> +evidence in favour of his own views as to the non-inheritance<span class="pagenum"><a name="Page_61" id="Page_61">[Pg 61]</a></span> +of acquired characters. This, however, +will have to be considered in its proper place further +on. Meanwhile I shall say merely in general terms +that it arises almost entirely from a confusion of +the doctrine of Continuity as absolute with that of +Continuity as partial, and therefore, as admitting of +degrees in different cases—which, as already explained, +are doctrines wide as the poles asunder. +But, leaving aside for the present such <i>prima facie</i> +evidence as Weismann has adduced on his side +of the issue, I may quote him as a hostile witness +to the weight of this kind of evidence <i>per contra</i>, +in so far as it has already been presented in the +foregoing chapter. Indeed, Weismann is much too +logical a thinker not to perceive the cogency of +the "appearances" which lie against his view of +Continuity as absolute—although he has not been +sufficiently careful in distinguishing between such +Continuity and that which admits of degrees.</p> + +<p>We may take it, then, as agreed on all hands that +whatever weight merely <i>prima facie</i> evidence may in +this matter be entitled to, is on the side of what +I have termed moderated Lamarckianism: first sight +"appearances" are against the Neo-Darwinian doctrine +of the absolute non-inheritance of acquired +characters.</p> + +<hr class="tb" /> + +<p>Let us now turn to another and much more +important line of indirect evidence in favour of +moderated Lamarckianism.</p> + +<p>The difficulty of <i>excluding the possibility</i> of natural +selection having been at work in the case of +wild plants and animals has already been noticed.<span class="pagenum"><a name="Page_62" id="Page_62">[Pg 62]</a></span> +Therefore we may now appreciate the importance +of all facts or arguments which <i>attenuate the probability</i> +of natural selection having been at work. +This may be done by searching for cases in nature +where a congenital structure, although unquestionably +adaptive, nevertheless presents so small an amount +of adaptation, that we can scarcely suppose it to +have been arrived at by natural selection in the +struggle for existence, as distinguished from the +inheritance of functionally-produced modifications. +For if functionally-produced modifications are ever +transmitted at all, there is no limit to the minuteness +of adaptive values which may thus become +congenital; whereas, in order that any adaptive +structure or instinct should be seized upon and accumulated +by natural selection, it must from the +very first have had an adaptive value sufficiently +great to have constituted its presence a matter of +life and death in the struggle for existence. Such +structures or instincts must not only have always +presented some measure of adaptive value, but +this must always have been sufficiently great to +reach what I have elsewhere called a selection-value. +Hence, if we meet with cases in nature where +adaptive structures or instincts present so low a +degree of adaptive value that it is difficult to conceive +how they could ever have exercised any +appreciable influence in the battle for life, such cases +may fairly be adduced in favour of the Lamarckian +theory. For example, the Neo-Lamarckian school of +the United States is chiefly composed of palaeontologists; +and the reason of this seems to be that +the study of fossil forms—or of species in process of<span class="pagenum"><a name="Page_63" id="Page_63">[Pg 63]</a></span> +formation—reveals so many instances of adaptations +which in their nascent condition present such exceedingly +minute degrees of adaptive value, that it +seems unreasonable to attribute their development to +a survival of the fittest in the complex struggle for +existence. But as this argument is in my opinion +of greatest force when it is applied to certain facts +of physiology with which I am about to deal, I will +not occupy space by considering any of the numberless +cases to which the Neo-Lamarckians apply it +within the region of palaeontology<a name="FNanchor_36_36" id="FNanchor_36_36"></a><a href="#Footnote_36_36" class="fnanchor">[36]</a>.</p> + +<p>Turning then to inherited actions, it is here that +we might antecedently expect to find our best evidence +of the Lamarckian principles, if these principles +have really had any share in the process of adaptive +evolution. For we know that in the life-time of +individuals it is action, and the cessation of action, +which produce nearly all the phenomena of acquired +adaptation—use and disuse in animals being merely +other names for action and the cessation of action. +Again, we know that it is where neuro-muscular +machinery is concerned that we meet with the most +conclusive evidence of the remarkable extent to +which action is capable of co-ordinating structures +for the ready performance of particular functions; +so that even during the years of childhood "practice +makes perfect" to the extent of organizing neuro-muscular +adjustments, so elaborate and complete as +to be indistinguishable from those which in natural<span class="pagenum"><a name="Page_64" id="Page_64">[Pg 64]</a></span> +species we recognized as reflex actions on the one +hand, and instinctive actions on the other. Hence, +if there be any such thing as "use-inheritance" at +all, it is in the domain of reflex actions and instinctive +actions that we may expect to find our best +evidence of the fact. Therefore I will restrict the +present line of evidence—(A)—to these two classes +of phenomena, as together yielding the best evidence +obtainable within this line of argument.</p> + +<hr class="tb" /> + +<p>The evidence in favour of the Lamarckian factors +which may be derived from the phenomena of reflex +action has never, I believe, been pointed out before; +but it appears to me of a more cogent nature than +perhaps any other. In order to do it justice, I will +begin by re-stating an argument in favour of these +factors which has already been adduced by previous +writers, and discussed by myself in published correspondence +with several leaders of the ultra-Darwinian +school.</p> + +<p>Long ago Professor Broca and Mr. Herbert Spencer +pointed to the facts of co-adaptation, or co-ordination +within the limits of the same organism, as presenting +good evidence of Lamarckian principles, working in +association with natural selection. Thus, taking one +of Lamarck's own illustrations, Mr. Spencer argued +that there must be numberless changes—extending to +all the organs, and even to all the tissues, of the +animal—which in the course of many generations +have conspired to convert an antelope into a giraffe. +Now the point is, that throughout the entire history +of these changes their utility must always have been +dependent on their association. It would be useless<span class="pagenum"><a name="Page_65" id="Page_65">[Pg 65]</a></span> +that an incipient giraffe should present the peculiar +form of the hind-quarters which we now perceive, +unless at the same time it presented the correspondingly +peculiar form of the fore-quarters; and as each +of these great modifications entails innumerable subordinate +modifications throughout both halves of the +creature concerned, the chances must have been infinitely +great against the required association of so many +changes happening to have arisen congenitally in the +same individuals by way of merely fortuitous variation. +Yet, if we exclude the Lamarckian interpretation, +which gives an intelligible <i>cause</i> of co-ordination, +we are required to suppose that such a happy concurrence +of innumerable independent variations must +have occurred by mere accident—and this on innumerable +different occasions in the bodies of as many +successive ancestors of the existing species. For at +each successive stage of the improvement natural +selection (if working alone) must have needed all, or +at any rate most, of the co-ordinated parts to occur in +the same individual organisms<a name="FNanchor_37_37" id="FNanchor_37_37"></a><a href="#Footnote_37_37" class="fnanchor">[37]</a>.</p> + +<p>In alluding to what I have already published upon +the difficulty which thus appears to be presented to +his theory, Weismann says, "At no distant time I hope +to be able to consider this objection, and to show that +the apparent support given to the old idea [i. e. of the +transmission of functionally-produced modifications] +is really insecure, and breaks down as soon as it is +critically examined<a name="FNanchor_38_38" id="FNanchor_38_38"></a><a href="#Footnote_38_38" class="fnanchor">[38]</a>."</p> +<p><span class="pagenum"><a name="Page_66" id="Page_66">[Pg 66]</a></span></p> +<p>So much for what Weismann has said touching this +matter. But the matter has also been dealt with both +by Darwin and by Wallace. Darwin very properly +distinguishes between the fallacy that "with animals +such as the giraffe, of which the whole structure is +admirably co-ordinated for certain purposes, it has +been supposed that all the parts must have been +simultaneously modified<a name="FNanchor_39_39" id="FNanchor_39_39"></a><a href="#Footnote_39_39" class="fnanchor">[39]</a>," and the sound argument +that the co-ordination itself cannot have been due to +natural selection alone. This important distinction +may be rendered more clear as follows.</p> + +<p>The facts of artificial selection prove that immense +modifications of structure may be caused by a cumulative +blending in the same individuals of characters +which were originally distributed among different +individuals. Now, in the parallel case of natural +selection the characters thus blended will usually—if +not invariably—be of an adaptive kind; and their +eventual blending together in the same individuals +will be due to free intercrossing of the most fit. +But this <i>blending of adaptations</i> is quite a different +matter from the <i>occurrence of co-ordination</i>. For +it belongs to the essence of co-ordination that each +of the co-ordinated parts should be destitute of adaptive +value <i>per se</i>: the adaptation only begins to arise +if all the parts in question occur associated together in +the same individuals <i>from the very first</i>. In this +case it is obvious that the analogy of artificial selection +can be of no avail in explaining the facts, +since the difficulty presented has nothing to do with<span class="pagenum"><a name="Page_67" id="Page_67">[Pg 67]</a></span> +the blending in single individuals of adaptations +previously distributed among different individuals; +it has to do with the simultaneous appearance in +single individuals of a co-adaptation of parts, none +of which could ever have been of any adaptive +value had it been previously distributed among +different individuals. Consequently, where Darwin +comes to consider this particular case (or the case +of co-adaptation as distinguished from the blending +of adaptations), he freely invokes the aid of the +Lamarckian principles<a name="FNanchor_40_40" id="FNanchor_40_40"></a><a href="#Footnote_40_40" class="fnanchor">[40]</a>.</p> + +<p>Wallace, on the other hand, refuses to do this, and +says that "the best answer to the difficulty" of supposing +natural selection to have been the only cause +of co-adaptation may be "found in the fact that +the very thing said to be impossible by variation +and natural selection, has been again and again +affected by variation and artificial selection<a name="FNanchor_41_41" id="FNanchor_41_41"></a><a href="#Footnote_41_41" class="fnanchor">[41]</a>." This +analogy (which Darwin had already and very properly +adduced with regard to the <i>blending of adaptations</i>) +he enforces by special illustrations; but he does not +appear to perceive that it misses the whole and +only point of the "difficulty" against which it is +brought. For the case which his analogy sustains +is not that which Darwin, Spencer, Broca and others, +mean by <i>co-adaptation</i>: it is the case of a blending +of <i>adaptations</i>. It is not the case where adaptation +is <i>first initiated in spite of intercrossing</i>, by a fortuitous +concurrence of variations each in itself being without +adaptive value: it is the case where adaptation +is <i>afterwards increased by means of intercrossing</i>,<span class="pagenum"><a name="Page_68" id="Page_68">[Pg 68]</a></span> +through the blending of variations each of which +has always been in itself of adaptive value.</p> + +<p>From this I hope it will be apparent that the only +way in which the "difficulty" from co-adaptation can +be logically met by the ultra-Darwinian school, is by +denying that the phenomenon of co-adaptation (as +distinguished from the blending of adaptations) is ever +to be really met with in organic nature. It may be +argued that in all cases where co-adaptation <i>appears</i> +to occur, closer examination will show that the facts +are really due to a blending of adaptations. The +characters A + B + C + D, which are now found united +in the same organism, and, as thus united, all conspiring +to a common end, may originally have been distributed +among different organisms, where they <i>severally</i> +subserved some other ends—or possibly the same +end, though in a less efficient manner. Obviously, +however, in this case their subsequent combination +in the same organism would not be an instance of +co-adaptation, but merely of an advantageous blending +together of already existing adaptations. This +argument, or rejoinder, has in point of fact been +adopted by Professor Meldola, he believes that all +cases of seeming co-adaptation are thus due to a +mere blending of adaptations<a name="FNanchor_42_42" id="FNanchor_42_42"></a><a href="#Footnote_42_42" class="fnanchor">[42]</a>. Of course, if this +position can be maintained, the whole difficulty<span class="pagenum"><a name="Page_69" id="Page_69">[Pg 69]</a></span> +from co-adaptation would lapse. But even then it +would lapse on the ground of <i>fact</i>. It would not +have been overturned, or in any way affected, by +Wallace's <i>argument</i> from artificial selection. For, in +that event, no such argument would be required, and, +if adduced, would be irrelevant, since no one has +ever alleged that there is any difficulty in understanding +the mere confluence of adaptations by free-intercrossing +of the best adapted.</p> + +<p>Now, if we are agreed that the only question in debate +is the question of fact whether or not co-adaptation +ever occurs in nature, it appears to me that the best +field for debating the question is furnished by the +phenomena of reflex action. I can well perceive that +the instances adduced by Broca and Spencer in support +of their common argument—such as the giraffe, the +elk, &c.—are equivocal. But I think that many +instances which may be adduced of reflex action are +much more to the point. <i>For it belongs to the very +nature of reflex action that it cannot work unless +all parts of the machinery concerned are already present, +and already co-ordinated, in the same organism.</i> +It would be useless, in so far as such action is concerned +if the afferent and efferent nerves, the nerve-centre, +and the muscles organically grouped together, +were not all present from the very first in the same +individuals, and from the very first were not co-ordinated +as a definite piece of organic machinery.</p> + +<p>With respect to reflex actions, therefore, it is +desirable to begin by pointing out how widely the<span class="pagenum"><a name="Page_70" id="Page_70">[Pg 70]</a></span> +adaptations which they involve differ from those where +no manufacture, so to speak, of special machinery is +required. Thus, it is easy to understand how natural +selection alone is capable of gradually accumulating +congenital variations in the direction of protective +colouring; of mimicry; of general size, form, mutual +correlation of parts as connected with superior strength, +fleetness, agility, &c.; of greater or less development +of particular parts, such as legs, wings, tails, &c. For +in all such cases the adaptation which is in process of +accumulation is from its very commencement and +throughout each of its subsequent stages, of <i>use</i> in +the struggle for existence. And inasmuch as all the +individuals of each successive generation vary round +the specific mean which characterized the preceding +generation, there will always be a sufficient number of +individuals which present congenital variations of the +kind required for natural selection to seize upon, +without danger of their being swamped by free intercrossing—as +Mr. Wallace has very ably shown in +his <i>Darwinism</i>. But this law of averages can apply +only to cases where single structures—or a single +group of correlated structures—are already present, +and already varying round a specific mean. The case +is quite different where a <i>co-ordination</i> of structures is +required for the performance of a <i>previously non-existent</i> +reflex action. For some, at least, of these structures +must be <i>new</i>, as must also be the function which all of +them first conspire to perform. Therefore, neither the +new elements of structure, nor the new combination of +structures, can have been previously given as varying +round a specific mean. On the contrary, a very +definite piece of machinery, consisting of many co-ordinated<span class="pagenum"><a name="Page_71" id="Page_71">[Pg 71]</a></span> +parts, must somehow or other be originated +in a high degree of working efficiency, before it can +be capable of answering its purpose in the prompt +performance of a particular action under particular +circumstances of stimulation. Lastly, such pieces of +machinery are always of a highly delicate character, +and usually involve so immensely complex a co-ordination +of mutually dependent parts, that it is only +a physiologist who can fully appreciate the magnitude +of the distinction between "adaptations" of this kind, +and "adaptations" of the kind which arise through +natural selection seizing upon congenital variations as +these oscillate round a specific mean.</p> + +<p>Or the whole argument may be presented in another +form, under three different headings, thus:—</p> + +<p>In the first place, it will be evident from what has +just been said, that such a piece of machinery as is concerned +in even the simplest reflex action cannot have +occurred in any considerable number of individuals +of a species, <i>when it first began to be constructed</i>. +On the contrary, if its <i>origin</i> were dependent on congenital +variations alone, the needful co-adaptation of +parts which it requires can scarcely have happened to +occur in more than a very small percentage of cases—even +if it be held conceivable that by such means +alone it should ever have occurred at all. Hence, +instead of preservation and subsequent improvement +having taken place <i>in consequence of</i> free intercrossing +among all individuals of the species (as in the cases +of protective colouring, &c., where adaptation has no +reference to any mechanical co-adaptation of parts), +they must have taken place <i>in spite of</i> such intercrossing.</p><p><span class="pagenum"><a name="Page_72" id="Page_72">[Pg 72]</a></span></p> + +<p>In the second place, adaptations due to organic +machineries of this kind differ in another all-important +respect from those due to a summation of adaptive +characters which are already present and already +varying round a specific mean. The latter depend for +their summation upon the fact—not merely, as just +stated, that they are already present, already varying +round a specific mean, and therefore owe their progressive +evolution to free intercrossing, but also—<i>that +they admit of very different degrees of adaptation</i>. It +is only because the degree of adaptation in generation +B is superior to that in generation A that <i>gradual +improvement</i> in respect of adaptation is here possible. +In the case of protective resemblance, for example, +a very imperfect and merely accidental resemblance +to a leaf, to another insect, &c., may at the first start +have conferred a sufficient degree of adaptive imitation +to count for something in the struggle for life; and, if +so, the basis would be given for a progressive building +up by natural selection of structures and colours +in ever-advancing degrees of adaptive resemblance. +There is here no necessity to suppose—nor in point +of fact is it ever supposed, since the supposition +would involve nothing short of a miracle—that such +extreme perfection in this respect as we now so frequently +admire has originated suddenly in a single +generation, as a collective variation of a congenital +kind affecting simultaneously a large proportional +number of individuals. But in the case of a reflex +mechanism—which may involve even greater marvels +of adaptive adjustment, and <i>all</i> the parts of which +must occur in the same <i>individuals</i> to be of any +use—it <i>is</i> necessary to suppose some such sudden<span class="pagenum"><a name="Page_73" id="Page_73">[Pg 73]</a></span> +and collective origin in some very high degree of +efficiency, if natural selection has been the only +principle concerned in afterwards perfecting the +mechanism. For it is self-evident that a reflex action, +from its very nature, cannot admit of any great +differences in its degrees of adaptation: if it is to +work at all, so as to count for anything in the struggle +for life, it must already be given in a state of working +efficiency. So that, unless we invoke either the +doctrine of "prophetic types" or the theory of sudden +creations, I confess I do not see how we are to explain +either the origin, or the development, of a reflex +mechanism by means of natural selection alone.</p> + +<p>Lastly, in the third place, <i>even when reflex +mechanisms have been fully formed</i>, it is often beyond +the power of sober credence to believe that they now +are, or ever can have been, of selective value in the +struggle for existence, as I will show further on. And +such cases go to fortify the preceding argument. For +if not conceivably of selective value even when completely +evolved, much less can they conceivably have +been so through all the stages of their complex +evolution back to their very origin. Therefore, supposing +for the present that there are such cases of +reflex action in nature, neither their origin nor their +development can conceivably have been due to +natural selection alone. The Lamarckian factors, +however, have no reference to degrees of adaptation, +any more than they have to degrees of complexity. +No question of value, as selective or otherwise, can +obtain in their case: neither in their case does any +difficulty obtain as regards the co-adaptation of +severally useless parts.</p><p><span class="pagenum"><a name="Page_74" id="Page_74">[Pg 74]</a></span></p> + +<p>Now, if all these distinctions between the Darwinian +and Lamarckian principles are valid—and +I cannot see any possibility of doubt upon this point—strong +evidence in favour of the latter would be +furnished by cases (if any occur) where structures, +actions, instincts, &c., although of some adaptive +value, are nevertheless plainly not of selective value. +According to the ultra-Darwinian theory, no such +cases ought ever to occur: according to the theory +of Darwin himself, they ought frequently to occur. +Therefore a good test, or criterion, as between these +different theories of organic evolution is furnished by +putting the simple question of fact—Can we, or can +we not, show that there are cases of adaptation where +the degree of adaptation is so small as to be incompatible +with the supposition of its presenting a selective +value? And if we put the wider question—Are there +any cases where the co-adaptation of severally useless +parts has been brought about, when even the resulting +whole does not present a selective value?—then, +of course, we impose a still more rigid test.</p> + +<p>Well, notwithstanding the difficulty of proving such +a negative as the absence of natural selection where +adaptive development is concerned, I believe that there +are cases which conform to both these tests simultaneously; +and, moreover, that they are to be found in +most abundance where the theory of use-inheritance +would most expect them to occur—namely, in the +province of reflex action. For the very essence of +this theory is the doctrine, that constantly associated +use of the same parts for the performance of the same +action will progressively organize those parts into +a reflex mechanism—no matter how high a degree of<span class="pagenum"><a name="Page_75" id="Page_75">[Pg 75]</a></span> +co-adaptation may thus be reached on the one hand, +or how low a degree of utilitarian value on the other.</p> + +<p>Having now stated the general or abstract principles +which I regard as constituting a defence of +the Lamarckian factors, so far as this admits of +being raised on grounds of physiology, we will now +consider a few concrete cases by way of illustration. +It is needless to multiply such cases for the +mere purpose of illustration. For, on reading those +here given, every physiologist will at once perceive +that they might be added to indefinitely. The +point to observe is, the relation in which these +samples of reflex action stand to the general +principles in question; for there is nothing unusual +in the samples themselves. On the contrary, they +are chosen because they are fairly typical of the +phenomena of reflex action in general.</p> + +<p>In our own organization there is a reflex mechanism +which ensures the prompt withdrawal of the legs +from any source of irritation supplied to the feet. +For instance, even after a man has broken his spine +in such a manner as totally to interrupt the functional +continuity of his spinal cord and brain, +the reflex mechanism in question will continue to +retract his legs when his feet are stimulated by +a touch, a burn, &c. This responsive action is +clearly an adaptive action, and, as the man neither +feels the stimulation nor the resulting movement, +it is as clearly a reflex action. The question now is +as to the mode of its origin and development.</p> + +<p>I will not here dwell upon the argument from +co-adaptation, because this may be done more +effectually in the case of more complicated reflex<span class="pagenum"><a name="Page_76" id="Page_76">[Pg 76]</a></span> +actions, but will ask whether we can reasonably +hold that this particular reflex action—comparatively +simple though it is—has ever been of selective +value to the human species, or to the ancestors +thereof? Even in its present fully-formed condition +it is fairly questionable whether it is of any +adaptive <i>value</i> at all. The movement performed is +no doubt an adaptive <i>movement</i>; but is there any +occasion upon which the reflex mechanism concerned +therein can ever have been of adaptive <i>use</i>? +Until a man's legs have been paralyzed as to +their voluntary motion, he will always promptly +withdraw his feet from any injurious source of +irritation by means of his conscious intelligence. +True, the reflex mechanism secures an almost inappreciable +saving in the time of response to a +stimulus, as compared with the time required for +response by an act of will; but the difference is +so exceedingly small, that we can hardly suppose +the saving of it in this particular case to be +a matter of any adaptive—much less selective—importance. +Nor is it more easy to suppose +that the reflex mechanism has been developed by +natural selection for the purpose of replacing voluntary +action when the latter has been destroyed or +suspended by grave spinal injury, paralysis, coma, +or even ordinary sleep. In short, even if for the +sake of argument we allow it to be conceivable that +any single human being, ape, or still more distant +ancestor, has ever owed its life to the possession of +this mechanism, we may still be certain that not one +in a million can have done so. And, if this is the +case with regard to the mechanism as now fully<span class="pagenum"><a name="Page_77" id="Page_77">[Pg 77]</a></span> +constructed, still more must it have been the case +with regard to all the previous stages of construction. +For here, without elaborating the point, it would +appear that a process of construction by survival of +the fittest alone is incomprehensible.</p> + +<p>On the other hand, of course, the theory of use-inheritance +furnishes a fully intelligible—whether or not +a true—explanation. For those nerve-centres in the +spinal cord which co-ordinate the muscles required for +retracting the feet are the centres used by the will +for this purpose. And, by hypothesis, the frequent +use of them for this purpose under circumstances +of stimulation which render the muscular response +appropriate, will eventually establish an organic +connexion between such response and the kind of +stimulation to which it is appropriate—even though +there be no utilitarian reason for its establishment<a name="FNanchor_43_43" id="FNanchor_43_43"></a><a href="#Footnote_43_43" class="fnanchor">[43]</a>. +To invert a phrase of Aristotle, we do not +frequently use this mechanism because we have it +(seeing that in our normal condition there is no +necessity for such use); but, by hypothesis, we have +it because we have frequently used its several elements +in appropriate combination.</p> + +<p>I will adduce but one further example in illustration +of these general principles—passing at once +from the foregoing case of comparative simplicity +to one of extreme complexity.</p> + +<p>There is a well-known experiment on a brainless +frog, which reveals a beautiful reflex mechanism in<span class="pagenum"><a name="Page_78" id="Page_78">[Pg 78]</a></span> +the animal, whereby the whole body is enabled continually +to readjust its balance on a book (or any +other plane surface), as this is slowly rotated on +a horizontal axis. So long as the book is lying flat, +the frog remains motionless; but as soon as the book +is tilted a little, so that the frog is in danger of +slipping off, all the four feet begin to crawl up the +hill; and the steeper the hill becomes, the faster +they crawl. When the book is vertical, the frog +has reached the now horizontal back, and so on. +Such being the facts, the question is—How can the +complicated piece of machinery thus implied have +been developed by natural selection? Obviously it +cannot have been so by any of the parts concerned +having been originally distributed among different +individuals, and afterwards united in single individuals +by survival (i.e. free intercrossing) of the fittest. +In other words, the case is obviously one of co-adaptation, +and not one of the blending of adaptations. +Again, and no less obviously, it is impossible that +the co-adaptation can have been <i>gradually developed</i> +by natural selection, because, in order to have been +so, it must by hypothesis have been of some degree +of use in every one of its stages; yet it plainly +cannot have been until it had been fully perfected +in all its astonishing complexity<a name="FNanchor_44_44" id="FNanchor_44_44"></a><a href="#Footnote_44_44" class="fnanchor">[44]</a>.</p> +<p><span class="pagenum"><a name="Page_79" id="Page_79">[Pg 79]</a></span></p> +<p>Lastly, not only does it thus appear impossible +that during all stages of its development—or while +as yet incapable of performing its intricate function—this +nascent mechanism can have had any adaptive +value; but even as now fully developed, who will +venture to maintain that it presents any selective +value? As long as the animal preserves its brain, +it will likewise preserve its balance, by the exercise +of its intelligent volition. And, if the brain were +in some way destroyed, the animal would be +unable to breed, or even to feed; so that natural +selection can never have had any <i>opportunity</i>, so +to speak, of developing this reflex mechanism in +brainless frogs. On the other hand, as we have just +seen, we cannot perceive how there can ever have +been any <i>raison d'être</i> for its development in normal +frogs—even if its development were conceivably +possible by means of this agency. But if practice +makes perfect in the race, as it does in the individual, +we can immediately perceive that the constant habit +of correctly adjusting its balance may have gradually +developed, in the batrachian organization, this non-necessary +reflex<a name="FNanchor_45_45" id="FNanchor_45_45"></a><a href="#Footnote_45_45" class="fnanchor">[45]</a>.</p> +<p><span class="pagenum"><a name="Page_80" id="Page_80">[Pg 80]</a></span></p> +<p>And, of course, this example—like that of withdrawing +the feet from a source of stimulation, which +a frog will do as well as a man—does not stand alone. +Without going further a-field than this same animal, +any one who reads, from our present point of view, +Goltz's work on the reflex actions of the frog, will +find that the great majority of them—complex and +refined though most of them are—cannot conceivably +have ever been of any use to any frog that was in +undisturbed possession of its brain.</p> + +<p>Hence, not to occupy space with a reiteration of +facts all more or less of the same general kind, +and therefore all presenting identical difficulties to +ultra-Darwinian theory, I shall proceed to give two +others which appear to me of particular interest in +the present connexion, because they furnish illustrations +of reflex actions in a state of only partial +development, and are therefore at the present moment +demonstrably useless to the animal which displays +them.</p> + +<p>Many of our domesticated dogs, when we gently +scratch their sides and certain other parts of the body, +will themselves perform scratching movements with +the hind leg of the same side as that upon which the +irritation is being supplied. According to Goltz<a name="FNanchor_46_46" id="FNanchor_46_46"></a><a href="#Footnote_46_46" class="fnanchor">[46]</a>, +this action is a true reflex; for he found that it is +performed equally well in a dog which has been +deprived of its cerebral hemispheres, and therefore +of its normal volition. Again, according to Haycraft<a name="FNanchor_47_47" id="FNanchor_47_47"></a><a href="#Footnote_47_47" class="fnanchor">[47]</a>,<span class="pagenum"><a name="Page_81" id="Page_81">[Pg 81]</a></span> +this reflex is congenital, or not acquired during the +life-time of each individual dog. Now, although the +action of scratching is doubtless adaptive, it appears +to me incredible that it could ever have become +organized into a congenital reflex by natural selection. +For, in order that it should, the scratching +away fleas would require to have been a function of +selective value. Yet, even if the irritation caused by +fleas were supposed to be so far fatal in the struggle +for existence, it is certain that they would always be +scratched away by the conscious intelligence of each +individual dog; and, therefore, that no advantage +could be gained by organizing the action into a +reflex. On the other hand, if acquired characters +are ever in any degree transmitted, it is easy to +understand how so frequently repeated an action +should have become, in numberless generations of +dogs, congenitally automatic.</p> + + +<p>So much for the general principle of selective +value as applied to this particular case. And similarly, +of course, we might here repeat the application<span class="pagenum"><a name="Page_82" id="Page_82">[Pg 82]</a></span> +of all the other general principles, which have just +been applied in the two preceding cases. But it is +only one of these other general principles which +I desire in the present case specially to consider, +for the purpose of considering more closely than +hitherto the difficulty which this principle presents +to ultra-Darwinian theory.</p> + +<p>The difficulty to which I allude is that of understanding +how all the stages in the <i>development</i> of +a reflex action can have been due to natural selection, +seeing that, before the reflex mechanism has been +sufficiently elaborated to perform its function, it cannot +have presented any degree of utility. Now the +particular force of the present example, the action +of scratching—as also of the one to follow—consists +in the fact that it is a case where a reflex action is +not yet completely organized. It appears to be only +in course of construction, so that it is neither invariably +present, nor, when it is present, is it ever +fully adapted to the performance of its function.</p> + +<p>That it is not invariably present (when the brain +is so) may be proved by trying the simple experiment +on a number of puppies—and also of full-grown +dogs. Again, that even when it is present +it is far from being fully adapted to the performance +of its function, may be proved by observing +that only in rare instances does the scratching +leg succeed in scratching the place which is being +irritated. The movements are made more or less at +random, and as often as not the foot fails to touch +the body at any place at all. Hence, although we +have a "prophecy" of a reflex action well designed +for the discharge of a particular function, at present<span class="pagenum"><a name="Page_83" id="Page_83">[Pg 83]</a></span> +the machinery is not sufficiently perfected for the +adequate discharge of that function. In this important +respect it differs from the otherwise closely +analogous reflex action of the frog, whereby the +foot of the hind leg is enabled to localize with +precision a seat of irritation on the side of the +body. But this beautiful mechanism in the frog cannot +have sprung into existence ready formed at any +historical moment in the past history of the phyla. +It must have been the subject of a more or less +prolonged evolution, in some stage of which it must +presumably have resembled the now nascent scratching +reflex of the dog, in making merely abortive +attempts at localizing the seat of irritation—supposing, +of course, that some physiologist had been there to +try the experiment by first removing the brain. +Now, even if one could imagine it to be, either in the +frog or in the dog, a matter of selective importance that +so exceedingly refined a mechanism should have been +developed for the sole purpose of inhibiting the bites +of parasites—which in every normal animal would +certainly be discharged by an <i>intentional</i> performance +of the movements in question,—even if, in order to +save an hypothesis at all costs, we make so violent +a supposition as this, still we should do so in vain. +For it would still remain undeniably certain that +the reflex mechanism is <i>not</i> of any selective value. +Even now the mechanism in the dog is not sufficiently +precise to subserve the only function which occasionally +and abortively it attempts to perform. Thus it has +all the appearance of being but an imitating shadow +of certain neuro-muscular adjustments, which have +been habitually performed in the canine phyla by a<span class="pagenum"><a name="Page_84" id="Page_84">[Pg 84]</a></span> +volitional response to cutaneous irritation. Were +it necessary, this argument might be strengthened +by observing that the reflex action is positively +<i>improved</i> by removal of the brain.</p> + +<p>The second example of a nascent reflex in dogs +which I have to mention is as follows.</p> + +<p>Goltz found that his brainless dogs, when wetted +with water, would shake themselves as dry as possible, +in just the same way as normal dogs will do under +similar circumstances. This, of course, proves that +the shaking movements may be performed by a +reflex mechanism, which can have no other function +to perform in the organization of a dog, and which, +besides being of a highly elaborate character, will +respond only to a very special kind of stimulation. +Now, here also I find that the mechanism is congenital, +or not acquired by individual experience. +For the puppies on which I experimented were kept +indoors from the time of their birth—so as never +to have had any experience of being wetted by rain, +&c.—till they were old enough to run about with +a full power of co-ordinating their general movements. +If these young animals were suddenly plunged into +water, the shock proved too great: they would +merely lie and shiver. But if their feet alone were +wetted, by being dipped in a basin of water, the +puppies would soon afterwards shake their heads in +the peculiar manner which is required for shaking +water off the ears, and which in adult dogs constitutes +the first phase of a general shaking of the +whole body.</p> + +<p>Here, then, we seem to have good evidence of all +the same facts which were presented in the case of the<span class="pagenum"><a name="Page_85" id="Page_85">[Pg 85]</a></span> +scratching reflex. In the first place, co-adaptation +is present in a very high degree, because this shaking +reflex in the dog, unlike the skin-twitching reflex +in the horse, does not involve only a single muscle, +or even a single group of muscles; it involves more +or less the co-ordinated activity of many voluntary +muscles all over the body. Such, at any rate, is +the case when the action is performed by the intelligent +volition of an adult dog; and if a brainless +dog, or a young puppy, does not perform it so +extensively or so vigorously, this only goes to prove +that the reflex has not yet been sufficiently developed +to serve as a substitute for intelligent volition—i.e. +that it is <i>useless</i>, or a mere organic shadow of the +really adaptive substance. Again, even if this nascent +reflex had been so far developed as to have been +capable of superseding voluntary action, still we may +fairly doubt whether it could have proved of selective +value. For it is questionable whether the immediate +riddance of water after a wetting is a matter +of life and death to dogs in a state of nature. +Moreover, even if it were, every individual dog would +always have got rid of the irritation, and so of +the danger, by means of a <i>voluntary</i> shake—with +the double result that natural selection has never +had any opportunity of gradually building up +a special reflex mechanism for the purpose of +securing a shake, and that the canine race have +not had to wait for any such unnecessary process. +Lastly, such a process, besides being unnecessary, +must surely have been, under any circumstances, +impossible. For even if we were to suppose—again +for the sake of saving an hypothesis at any<span class="pagenum"><a name="Page_86" id="Page_86">[Pg 86]</a></span> +cost—that the presence of a fully-formed shaking +reflex is of selective value in the struggle for existence, +it is perfectly certain that all the stages +through which the construction of so elaborate a +mechanism must have passed could not have been, +under any circumstances, of any such value.</p> + +<p>But, it is needless to repeat, according to the +hypothesis of use-inheritance, there is no necessity +to suppose that these incipient reflex mechanisms +<i>are</i> of any value. If function produces structure in +the race as it does in the individual, the voluntary +and frequently repeated actions of scratching and +shaking may very well have led to an organic +integration of the neuro-muscular mechanisms concerned. +Their various parts having been always +co-ordinated for the performance of these actions by +the intelligence of innumerable dogs in the past, +their co-adapted activity in their now automatic +responses to appropriate stimuli presents no difficulty. +And the consideration that neither in their prospectively +more fully developed condition, nor, <i>a fortiori</i>, +in their present and all previous stages of evolution, +can these reflex mechanisms be regarded as presenting +any selective—or even so much as any adaptive—value, +is neither more nor less than the theory of +use-inheritance would expect.</p> + +<p>Thus, with regard to the phenomena of reflex action +in general, all the facts are such as this theory requires, +while many of the facts are such as the theory of +natural selection alone cannot conceivably explain. +Indeed, it is scarcely too much to say, that most +of the facts are such as directly contradict the latter +theory in its application to them. But, be this<span class="pagenum"><a name="Page_87" id="Page_87">[Pg 87]</a></span> +as it may, at present there are only two hypotheses +in the field whereby to account for the facts +of adaptive evolution. One of these hypotheses +is universally accepted, and the only question is +whether we are to regard it as <i>alone</i> sufficient to explain +<i>all</i> the facts. The other hypothesis having been +questioned, we can test its validity only by finding +cases which it is fully capable of explaining, and +which do not admit of being explained by its companion +hypothesis. I have endeavoured to show +that we have a large class of such cases in the +domain of reflex action, and shall next endeavour to +show that there is another large class in the domain +of instinct.</p> + +<hr class="tb" /> + +<p>If instinct be, as Professor Hering, Mr. Samuel +Butler, and others have argued, "hereditary habit"—i. e. +if it comprises an element of transmitted experience—we +at once find a complete explanation of +many cases of the display of instinct which otherwise +remain inexplicable. For although a large number—or +even, as I believe, a large majority—of instincts +are explicable by the theory of natural selection alone, +or by supposing that they were gradually developed +by the survival of fortuitous variations in the way of +advantageous psychological peculiarities, this only +applies to comparatively simple instincts, such as that +of a protectively coloured animal exhibiting a preference +for the surroundings which it resembles, or even +adopting attitudes in imitation of objects which occur +in such surroundings. But in all cases where instincts +become complex and refined, we seem almost compelled +to accept Darwin's view that their origin is to<span class="pagenum"><a name="Page_88" id="Page_88">[Pg 88]</a></span> +be sought in consciously intelligent adjustments on +the part of ancestors.</p> + +<p>Thus, to give only one example, a species of +Sphex preys upon caterpillars, which it stings in +their nerve-centres for the purpose of paralyzing, +without killing them. The victims, when thus rendered +motionless, are then buried with the eggs of +the Sphex, in order to serve as food for her larvae +which subsequently develop from these eggs. Now, +in order thus to paralyze a caterpillar, the Sphex has +to sting it successively in nine minute and particular +points along the ventral surface of the animal—and +this the Sphex unerringly does, to the exclusion +of all other points of the caterpillar's anatomy. Well, +such being the facts—according to M. Fabre, who +appears to have observed them carefully—it is conceivable +enough, as Darwin supposed<a name="FNanchor_48_48" id="FNanchor_48_48"></a><a href="#Footnote_48_48" class="fnanchor">[48]</a>, that the +ancestors of the Sphex, being like many other hymenopterous +insects highly intelligent, should have +observed that on stinging caterpillars in these particular +spots a greater amount of effect was produced than +could be produced by stinging them anywhere else; +and, therefore, that they habitually stung the caterpillars +in these places only, till, in course of time, this +originally intelligent habit became by heredity instinctive. +But now, on the other hand, if we exclude the +possibility of this explanation, it appears to me incredible +that such an instinct should ever have been +evolved at all; for it appears to me incredible that +natural selection, unaided by originally intelligent +action, could ever have developed such an instinct<span class="pagenum"><a name="Page_89" id="Page_89">[Pg 89]</a></span> +out of merely fortuitous variations—there being, by +hypothesis, nothing to <i>determine</i> variations of an +insect's mind in the direction of stinging caterpillars +only in these nine intensely localized spots<a name="FNanchor_49_49" id="FNanchor_49_49"></a><a href="#Footnote_49_49" class="fnanchor">[49]</a>.</p> + +<p>Again, there are not a few instincts which appear +to be wholly useless to their possessors, and others +again which appear to be even deleterious. The +dusting over of their excrement by certain freely-roaming +carnivora; the choice by certain herbivora +of particular places on which to void their urine, or +in which to die; the howling of wolves at the moon; +purring of cats, &c., under pleasurable emotion; and +sundry other hereditary actions of the same apparently +unmeaning kind, all admit of being readily +accounted for as useless habits originally acquired +in various ways, and afterwards perpetuated by +heredity, because not sufficiently deleterious to have +been stamped out by natural selection<a name="FNanchor_50_50" id="FNanchor_50_50"></a><a href="#Footnote_50_50" class="fnanchor">[50]</a>. But it does +not seem possible to explain them by survival of the +fittest in the struggle for existence.</p> + +<p>Finally, in the case of our own species, it is self-evident +that the aesthetic, moral, and religious instincts +admit of a natural and easy explanation on the +hypothesis of use-inheritance, while such is by no +means the case if that hypothesis is rejected. Our +emotions of the ludicrous, of the beautiful, and of the +sublime, appear to be of the nature of hereditary +instincts; and be this as it may, it would further +appear that, whatever else they may be, they are +certainly not of a life-preserving character. And<span class="pagenum"><a name="Page_90" id="Page_90">[Pg 90]</a></span> +although this cannot be said of the moral sense when +the theory of natural selection is extended from the +individual to the tribe, still, when we remember the +extraordinary complexity and refinement to which +they have attained in civilized man, we may well +doubt whether they can have been due to natural +selection alone. But space forbids discussion of this +large and important question on the present occasion. +Suffice it therefore to say, that I doubt not Weismann +himself would be the first to allow that his theory of +heredity encounters greater difficulties in the domain +of ethics than in any other—unless, indeed, it be that +of religion<a name="FNanchor_51_51" id="FNanchor_51_51"></a><a href="#Footnote_51_51" class="fnanchor">[51]</a>.</p> + +<hr class="tb" /> + +<p>I have now given a brief sketch of the indirect +evidence in favour of the so-called Lamarckian factors, +in so far as this appears fairly deducible from the +facts of reflex action and of instinct. It will now be +my endeavour to present as briefly what has to be said +against this evidence.</p> + +<p>As previously observed, the facts of reflex action +have not been hitherto adduced in the present connexion. +This has led me to occupy considerably +more space in the treatment of them than those of +instinct. On this account, also, there is here nothing +to quote, or to consider, <i>per contra</i>. On the other +hand, however, Weismann has himself dealt with the +phenomena of instinct in animals, though not, I think, +in man—if we except his brilliant essay on music. +Therefore let us now begin this division of our<span class="pagenum"><a name="Page_91" id="Page_91">[Pg 91]</a></span> +subject by briefly stating, and considering, what he +has said upon the subject.</p> + +<p>The answer of Weismann to difficulties which arise +against the ultra-Darwinian theory in the domain of +instinct, is as follows:—</p> + +<blockquote><p>"The necessity for extreme caution in appealing to the supposed +hereditary effects of use, is well shown in the case of those +numerous instincts which only come into play once in a life-time, +and which do not therefore admit of improvement by practice. +The queen-bee takes her nuptial flight only once, and yet how +many and complex are the instincts and the reflex mechanisms +which come into play on that occasion. Again, in many insects +the deposition of eggs occurs but once in a life-time, and yet +such insects always fulfil the necessary conditions with unfailing +accuracy<a name="FNanchor_52_52" id="FNanchor_52_52"></a><a href="#Footnote_52_52" class="fnanchor">[52]</a>."</p></blockquote> + +<p>But in this rejoinder the possibility is forgotten, +that although such actions are <i>now</i> performed only +once in the individual life-time, <i>originally</i>—i.e. when +the instincts were being developed in a remote +ancestry—they may have been performed on many +frequent and successive occasions during the individual +life-time. In all the cases quoted by Weismann, +instincts of the kind in question bear independent +evidence of high antiquity, by occurring in whole +genera (or even families), by being associated with +peculiar and often highly evolved structures required +for their performance, and so on. Consequently, in +these cases ample time has been allowed for subsequent +changes of habit, and of seasonal alterations +with respect to propagation—both these things being +of frequent and facile occurrence among animals of all +kinds, even within periods which fall under actual<span class="pagenum"><a name="Page_92" id="Page_92">[Pg 92]</a></span> +observation. Nevertheless, I do not question that +there are instinctive activities which, as far as we are +able to see, can never have been performed more +than once in each individual life-time<a name="FNanchor_53_53" id="FNanchor_53_53"></a><a href="#Footnote_53_53" class="fnanchor">[53]</a>. The fact, +however, only goes to show what is fully admitted—that +some instincts (and even highly complex instincts) +have apparently been developed by natural selection +alone. Which, of course, is not equivalent to showing +that all instincts must have been developed by natural +selection alone. The issue is not to be debated on +general grounds like this, but on those of particular +cases. Even if it were satisfactorily proved that the +instincts of a queen-bee have been developed by +natural selection, it would not thereby be proved +that such has been the case with the instincts of +a Sphex wasp. One can very well understand how +the nuptial flight of the former, with all its associated +actions, may have been brought about by natural +selection alone; but this does not help us to understand +how the peculiar instincts of the latter can have +been thus caused.</p> + +<p>Strong evidence in favour of Weismann's views +does, however, at first sight seem to be furnished by +social hymenoptera in other respects. For not only +does the queen present highly specialized and altogether +remarkable instincts; but the neuters present +totally different and even still more remarkable +instincts—which, moreover, are often divided into +two or more classes, corresponding with the different +"castes." Yet the neuters, being barren females, +never have an opportunity of bequeathing their +instincts to progeny. Thus it appears necessary to<span class="pagenum"><a name="Page_93" id="Page_93">[Pg 93]</a></span> +suppose that the instincts of all the different castes of +neuters are latent in the queen and drones, together +with the other instincts which are patent in both. +Lastly, it seems necessary to suppose that all this +wonderful organization of complex and segregated +instincts must have been built up by natural selection +acting exclusively on the queens and drones—seeing +that these exercise their own instincts only once in +a life-time, while, as just observed, the neuters cannot +possibly bequeath their individual experience to +progeny. Obviously, however, natural selection must +here be supposed to be operating at an immense +disadvantage; for it must have built up the often +diverse and always complex instincts of neuters, not +directly, but indirectly through the queens and drones, +which never manifest any of these instincts themselves.</p> + +<p>Now Darwin fully acknowledged the difficulty of +attributing these results to the unaided influence of +natural selection; but the fact of neuter insects being +unable to propagate seemed to him to leave no +alternative. And so it seems to Weismann, who +accordingly quotes these instincts in support of his +views. And so it seemed to me, until my work +on <i>Animal Intelligence</i> was translated into French, +and an able Preface was supplied to that translation +by M. Perrier. In this Preface it is argued that we +are not necessarily obliged to exclude the possibility +of Lamarckian principles having operated in the +original formation of these instincts. On the contrary, +if such principles ever operate at all, Perrier shows +that here we have a case where it is virtually certain +that they must have operated. For although neuter +insects are now unable to propagate, their organization<span class="pagenum"><a name="Page_94" id="Page_94">[Pg 94]</a></span> +indicates—if it does not actually prove—that +they are descended from working insects which were +able to propagate. Thus, in all probability, what we +now call a "hive" was originally a society of sexually +mature insects, all presenting the same instincts, both +as to propagation and to co-operation. When these +instincts, thus common to all individuals composing +the hive, had been highly perfected, it became of +advantage in the struggle for existence (between +different hives or communities) that the functions +of reproduction should devolve more upon some +individuals, while those of co-operation should devolve +more upon others. Consequently, this division of +labour began, and gradually became complete, as +we now find it in bees and ants. Perrier sustains +the hypothesis thus briefly sketched by pointing +to certain species of social hymenoptera where +we may actually observe different stages of the +process—from cases where all the females of the +hive are at the same time workers and breeders, up +to the cases where the severance between these functions +has become complete. Therefore, it seems to +me, it is no longer necessary to suppose that in these +latter cases all the instincts of the (now) barren females +can only have been due to the unaided influence of +natural selection.</p> + +<p>Nevertheless, although I think that Perrier has +made good his position thus far, that his hypothesis +fails to account for some of the instincts which are +manifested by neuter insects, such as those which, so +far as I can see, must necessarily be supposed to +have originated after the breeding and working +functions had become separated—seeing that they<span class="pagenum"><a name="Page_95" id="Page_95">[Pg 95]</a></span> +appear to have exclusive reference to this peculiar +state of matters. Possibly, however, Perrier might +be able to meet each of these particular instincts, +by showing how they could have arisen out of +simpler beginnings, prior to the separation of the two +functions in question. There is no space to consider +such possibilities in detail; but, until this shall +have been done, I do not think we are entitled to +conclude that the phenomena of instinct as presented +by neuter insects are demonstrably incompatible with +the doctrines of Lamarck—or, that these phenomena +are available as a logical proof of the unassisted +agency of natural selection in the case of instincts +in general<a name="FNanchor_54_54" id="FNanchor_54_54"></a><a href="#Footnote_54_54" class="fnanchor">[54]</a>.</p> + + +<h3>(B.)<br /> +<i>Inherited Effects of Use and of Disuse.</i></h3> + +<p>There is no doubt that Darwin everywhere attaches +great weight to this line of evidence. Nevertheless, +in my opinion, there is equally little doubt that, +taken by itself, it is of immeasurably less weight than +Darwin supposed. Indeed, I quite agree with Weismann +that the whole of this line of evidence is +practically worthless; and for the following reasons.</p> + +<p>The evidence on which Darwin relied to prove<span class="pagenum"><a name="Page_96" id="Page_96">[Pg 96]</a></span> +the inherited effects of use and disuse was derived +from his careful measurements of the increase or +decrease which certain bones of our domesticated +animals have undergone, as compared with the corresponding +bones of ancestral stocks in a state of +nature. He chose domesticated animals for these +investigations, because, while yielding unquestionable +cases of increased or diminished use of certain organs +over a large number of sequent generations, the results +were not complicated by the possible interference +of natural selection on the one hand, or by that +of the economy of nutrition on the other. For "with +highly-fed domesticated animals there seems to be +no economy of growth, or any tendency to the elimination +of superfluous details<a name="FNanchor_55_55" id="FNanchor_55_55"></a><a href="#Footnote_55_55" class="fnanchor">[55]</a>;" seeing that, among +other considerations pointing in the same direction, +"structures which are rudimentary in the parent +species, sometimes become partially re-developed in +our domesticated productions<a name="FNanchor_56_56" id="FNanchor_56_56"></a><a href="#Footnote_56_56" class="fnanchor">[56]</a>."</p> + +<p>The method of Darwin's researches in this connexion +was as follows. Taking, for example, the case +of ducks, he carefully weighed and measured the +wing-bones and leg-bones of wild and tame ducks; +and he found that the wing-bones were smaller, +while the leg-bones were larger, in the tame than in +the wild specimens. These facts he attributed to many +generations of tame ducks using their wings less, and +their legs more, than was the case with their wild +ancestry. Similarly he compared the leg-bones of +wild rabbits with those of tame ones, and so forth—in +all cases finding that where domestication had led +to increased use of a part, that part was larger than in<span class="pagenum"><a name="Page_97" id="Page_97">[Pg 97]</a></span> +the wild parent stock; while the reverse was the case +with parts less used. Now, although at first sight +these facts certainly do seem to yield good evidence +of the inherited effects of use and disuse, they are +really open to the following very weighty objections.</p> + +<p>First of all, there is no means of knowing how +far the observed effects may have been due to increased +or diminished use during only the individual +life-time of each domesticated animal. Again, and +this is a more important point, in all Darwin's +investigations the increase or decrease of a part +was estimated, not by directly comparing, say the +wing-bones of a domesticated duck with the wing-bones +of a wild duck, but by comparing the <i>ratio</i> +between the wing and leg bones of a tame duck +with the <i>ratio</i> between the wing and leg bones +of a wild duck. Consequently, if there be any reason +to doubt the supposition that a really inherited +decrease in the size of a part thus estimated is due +to the inherited effects of disuse, such a doubt will +also extend to the evidence of increased size being +due to the inherited effects of use. Now there is the +gravest possible doubt lying against the supposition +that any really inherited decrease in the size of a +part is due to the inherited effects of disuse. For +it may be—and, at any rate to some extent, must +be—due to another principle, which it is strange that +Darwin should have overlooked. This is the principle +which Weismann has called Panmixia, and which +cannot be better expressed than in his own words:—</p> + +<blockquote><p>"A goose or a duck must possess strong powers of flight in the +natural state, but such powers are no longer necessary for +obtaining food when it is brought into the poultry-yard; so<span class="pagenum"><a name="Page_98" id="Page_98">[Pg 98]</a></span> +that a rigid selection of individuals with well-developed wings +at once ceases among its descendants. Hence, in the course +of generations, a deterioration of the organs of flight must +necessarily ensue<a name="FNanchor_57_57" id="FNanchor_57_57"></a><a href="#Footnote_57_57" class="fnanchor">[57]</a>."</p></blockquote> + +<p>Or, to state the case in another way: if any +structure which was originally built up by natural +selection on account of its use, ceases any longer +to be of so much use, in whatever degree it ceases +to be of use, in that degree will the premium before +set upon it by natural selection be withdrawn. And +the consequence of this withdrawal of selection as +regards that particular part will be to allow the +part to degenerate in successive generations. Such +is the principle which Weismann calls Panmixia, +because, by the withdrawal of selection from any +particular part, promiscuous breeding ensues with +regard to that part. And it is easy to see that +this principle must be one of very great importance +in nature; because it must necessarily come into +operation in all cases where any structure or any +instinct has, through any change in the environment +or in the habits of a species, ceased to be useful. +It is likewise easy to see that its effect must be +the same as that which was attributed by Darwin +to the inherited effect of disuse; and, therefore, that +the evidence on which he relied in proof of the +inherited effects both of use and of disuse is vitiated +by the fact that the idea of Panmixia did not occur to +him.</p> + +<p>Here, however, it may be said that the idea first +occurred to me<a name="FNanchor_58_58" id="FNanchor_58_58"></a><a href="#Footnote_58_58" class="fnanchor">[58]</a> just after the publication of the<span class="pagenum"><a name="Page_99" id="Page_99">[Pg 99]</a></span> +last edition of the <i>Origin of Species</i>. I called the +principle the Cessation of Selection—which I still +think a better, because a more descriptive, term +than Panmixia; and at that time it appeared to me, +as it now appears to Weismann, entirely to supersede +the necessity of supposing that the effect of disuse is +ever inherited in any degree at all. Thus it raised +the whole question as to the admissibility of Lamarckian +principles in general; or the question on +which we are now engaged touching the possible +inheritance of acquired, as distinguished from congenital, +characters. But on discussing the matter +with Mr. Darwin, he satisfied me that the larger +question was not to be so easily closed. That is to +say, although he fully accepted the principle of the +Cessation of Selection, and as fully acknowledged +its obvious importance, he convinced me that there +was independent evidence for the transmission of +acquired characters, sufficient in amount to leave +the general structure of his previous theory unaffected +by what he nevertheless recognized as a factor which +must necessarily be added. All this I now mention +in order to show that the issue which Weismann +has raised since Darwin's death was expressly contemplated +during the later years of Darwin's life. +For if the idea of Panmixia—in the absence of which +Weismann's entire system would be impossible—had +never been present to Darwin's mind, we should +have been left in uncertainty how he would have +regarded this subsequent revolt against what are +generally called the Lamarckian principles<a name="FNanchor_59_59" id="FNanchor_59_59"></a><a href="#Footnote_59_59" class="fnanchor">[59]</a>.</p> + +<p>Moreover, in this connexion we must take particular<span class="pagenum"><a name="Page_100" id="Page_100">[Pg 100]</a></span> +notice that the year after I had published +these articles on the Cessation of Selection, and +discussed with Mr. Darwin the bearing of this principle +on the question of the transmission of acquired +characters, Mr. Galton followed with his highly +important essay on Heredity. For in this essay +Mr. Galton fully adopted the principle of the Cessation +of Selection, and was in consequence the first +publicly to challenge the Lamarckian principles—pointing +out that, if it were thus possible to deny +the transmission of acquired characters <i>in toto</i>, "we +should be relieved from all further trouble"; but +that, if such characters are transmitted "in however +faint a degree, a complete theory of heredity must +account for them." Thus the question which, in its +revived condition, is now attracting so much attention, +was propounded in all its parts some fifteen or sixteen +years ago; and no additional facts or new +considerations of any great importance bearing upon +the subject have been adduced since that time. In +other words, about a year after my own conversations +with Mr. Darwin, the whole matter was still more +effectively brought before his notice by his own +cousin. And the result was that he still retained his +belief in the Lamarckian factors of organic evolution, +even more strongly than it was retained either by +Mr. Galton or myself<a name="FNanchor_60_60" id="FNanchor_60_60"></a><a href="#Footnote_60_60" class="fnanchor">[60]</a>.</p> + +<p>We have now considered the line of evidence on +which Darwin chiefly relied in proof of the transmissibility +of acquired characters; and it must be allowed +that this line of evidence is practically worthless.<span class="pagenum"><a name="Page_101" id="Page_101">[Pg 101]</a></span> +What he regarded as the inherited effects of use and +of disuse may be entirely due to the cessation of +selection in the case of our domesticated animals, +combined with an active <i>reversal</i> of selection in the +case of natural species. And in accordance with +this view is the fact that the degeneration of disused +parts proceeds much further in the case of wild +species than it does in that of domesticated varieties. +For although it may be said that in the case of wild +species more time has been allowed for a greater +accumulation of the inherited effects of disuse than +can have been the case with domesticated varieties, +the alternative explanation is at least as probable—that +in the case of wild species the merely negative, +or passive, influence of the <i>cessation</i> of selection has +been continuously and powerfully assisted by the +positive, or active, influence of the <i>reversal</i> of selection, +through economy of growth and the general advantage +to be derived from the abolition of useless parts<a name="FNanchor_61_61" id="FNanchor_61_61"></a><a href="#Footnote_61_61" class="fnanchor">[61]</a>.</p> + +<p>The absence of any good evidence of this direct +kind in favour of use-inheritance will be rendered +strikingly apparent to any one who reads a learned +and interesting work by Professor Semper<a name="FNanchor_62_62" id="FNanchor_62_62"></a><a href="#Footnote_62_62" class="fnanchor">[62]</a>. His +object was to show the large part which he believed +to have been played by external conditions of life in +directly modifying organic types—or, in other words, +of proving that side of Lamarckianism which refers +to the immediate action of the environment, whether +with or without the co-operation of use-inheritance +and natural selection. Although Semper gathered<span class="pagenum"><a name="Page_102" id="Page_102">[Pg 102]</a></span> +together a great array of facts, the more carefully +one reads his book the more apparent does it become +that no single one of the facts is in itself conclusive +evidence of the transmission to progeny of characters +which are acquired through use-inheritance or +through direct action of the environment. Every one +of the facts is susceptible of explanation on the +hypothesis that the principle of natural selection +has been the only principle concerned. This, however, +it must be observed, is by no means equivalent +to proving that characters thus acquired are not +transmitted. As already pointed out, it is impracticable +with species in a state of nature to dissociate +the distinctively Darwinian from the possibly +Lamarckian factors; so that even if the latter +are largely operative, we can only hope for direct +evidence of the fact from direct experiments on +varieties in a state of domestication. To this branch +of our subject, therefore, we will now proceed.</p> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_103" id="Page_103">[Pg 103]</a></p> + + + + +<h2>CHAPTER IV.<br /> +<span class="smcap">Characters As Hereditary and Acquired</span><br /> +(<i>continued</i>).</h2> + + +<h3>(C.)<br /> +<i>Experimental Evidence in favour of the Inheritance +of Acquired Characters.</i></h3> + +<p>Notwithstanding the fact already noticed, that +no experiments have hitherto been published with +reference to the question of the transmission of +acquired characters<a name="FNanchor_63_63" id="FNanchor_63_63"></a><a href="#Footnote_63_63" class="fnanchor">[63]</a>, there are several researches<span class="pagenum"><a name="Page_104" id="Page_104">[Pg 104]</a></span> +which, with other objects in view, have incidentally +yielded seemingly good evidence of such transmission. +The best-known of these researches—and therefore +the one with which I shall begin—is that of Brown-Séquard +touching the effects of certain injuries of the +nervous system in guinea-pigs.</p> + +<p>During a period of thirty years Brown-Séquard +bred many thousands of guinea-pigs as material for +his various researches; and in those whose parents +had not been operated upon in the ways to be +immediately mentioned, he never saw any of the +peculiarities which are about to be described. Therefore +the hypothesis of coincidence, at all events, must +be excluded. The following is his own summary +of the results with which we are concerned:—</p> + +<blockquote><p>1st. Appearance of epilepsy in animals born of parents which +had been rendered epileptic by an injury to the spinal cord.</p> + +<p>2nd. Appearance of epilepsy also in animals born of parents +which had been rendered epileptic by section of the sciatic nerve.</p> + +<p>3rd. A change in the shape of the ear in animals born of +parents in which such a change was the effect of a division +of the cervical sympathetic nerve.</p> + +<p>4th. Partial closure of the eyelids in animals born of parents<span class="pagenum"><a name="Page_105" id="Page_105">[Pg 105]</a></span> +in which that state of the eyelids had been caused either by +section of the cervical sympathetic nerve, or the removal of the +superior cervical ganglion.</p> + +<p>5th. Exophthalmia in animals born of parents in which an +injury to the restiform body had produced that protrusion of the +eyeball. This interesting fact I have witnessed a good many +times, and seen the transmission of the morbid state of the +eye continue through four generations. In these animals, +modified by heredity, the two eyes generally protruded, although +in the parents usually only one showed exophthalmia, the lesion +having been made in most cases only on one of the corpora +restiformia.</p> + +<p>6th. Haematoma and dry gangrene of the ears in animals +born of parents in which these ear-alterations had been caused +by an injury to the restiform body near the nib of the calamus.</p> + +<p>7th. Absence of two toes out of the three of the hind leg, and +sometimes of the three, in animals whose parents had eaten up +their hind-leg toes which had become anaesthetic from a section +of the sciatic nerve alone, or of that nerve and also of the crural. +Sometimes, instead of complete absence of the toes, only a part +of one or two or three was missing in the young, although in the +parent not only the toes but the whole foot were absent (partly +eaten off, partly destroyed by inflammation, ulceration, or +gangrene.)</p> + +<p>8th. Appearance of various morbid states of the skin and +hair of the neck and face in animals born of parents having had +similar alterations in the same parts, as effects of an injury to +the sciatic nerve.</p></blockquote> + +<p>These results<a name="FNanchor_64_64" id="FNanchor_64_64"></a><a href="#Footnote_64_64" class="fnanchor">[64]</a> have been independently vouched +for by two of Brown-Séquard's former assistants—Dr. +Dupuy, and the late Professor Westphal. +Moreover, his results with regard to epilepsy have +been corroborated also by Obersteiner<a name="FNanchor_65_65" id="FNanchor_65_65"></a><a href="#Footnote_65_65" class="fnanchor">[65]</a>. I may<span class="pagenum"><a name="Page_106" id="Page_106">[Pg 106]</a></span> +observe, in passing, that this labour of testing Brown-Séquard's +statements is one which, in my opinion, +ought rather to have been undertaken, if not by +Weismann himself, at all events by some of his +followers. Both he and they are incessant in their +demand for evidence of the transmission of acquired +characters; yet they have virtually ignored the foregoing +very remarkable statements. However, be +this as it may, all that we have now to do is to +consider what the school of Weismann has had to say +with regard to these experiments on the grounds of +general reasoning which they have thus far been +satisfied to occupy.</p> + +<p>In view of Obersteiner's corroboration of Brown-Séquard's +results touching the artificial production +and subsequent transmission of epilepsy, Weismann +accepts the facts, but, in order to save his theory +of heredity, he argues that the transmission may +be due to a traumatic introduction of "some unknown +microbe" which causes the epilepsy in the parent, +and, by invading the ova or spermatozoa as the +case may be, also produces epilepsy in the offspring. +Here, of course, there would be transmission of +epilepsy, but it would not be, technically speaking, +an hereditary transmission. The case would resemble +that of syphilis, where the sexual elements remain +unaffected as to their congenital endowments, although +they have been made the vehicles for conveying an +organic poison to the next generation.</p> + +<p>Now it would seem that this suggestion is not, +on the face of it, a probable one. For "some unknown +microbe" it indeed must be, which is always +on hand to enter a guinea-pig when certain operations<span class="pagenum"><a name="Page_107" id="Page_107">[Pg 107]</a></span> +are being performed on certain parts of the nervous +system, but yet will never enter when operations +of any kind are being effected elsewhere. Moreover, +Westphal has produced the epilepsy <i>without any +incision</i>, by striking the heads of the animals with +a hammer<a name="FNanchor_66_66" id="FNanchor_66_66"></a><a href="#Footnote_66_66" class="fnanchor">[66]</a>. This latter fact, it appears to me, +entirely abolishes the intrinsically improbable suggestion +touching an unknown—and strangely eclectic—microbe. +However, it is but fair to state what +Weismann himself has made of this fact. The following +is what he says:—</p> + +<blockquote><p>"It is obvious that the presence of microbes can have nothing +to do with such an attack, but the shock alone must have caused +morphological and functional changes in the centre of the pons +and medulla oblongata, identical with those produced by microbes +in the other cases.... Various stimuli might cause the nervous +centres concerned to develop the convulsive attack which, +together with its after-effects, we call epilepsy. In Westphal's +case, such a stimulus would be given by a powerful mechanical +shock (viz. blows on the head with a hammer); in Brown-Séquard's +experiments, by the penetration of microbes<a name="FNanchor_67_67" id="FNanchor_67_67"></a><a href="#Footnote_67_67" class="fnanchor">[67]</a>."</p></blockquote> + +<p>But from this passage it would seem that Weismann +has failed to notice that in "Westphal's case," as +in "Brown-Séquard's experiments," the epilepsy was +<i>transmitted to progeny</i>. That epilepsy may be produced +in guinea-pigs by a method which does not +involve any cutting (i.e. possibility of inoculation) +would no doubt tend to corroborate the suggestion +of microbes being concerned in its transmission when +it is produced by cutting, <i>if in the former case there +were no such transmission</i>. But as there <i>is</i> transmission +in <i>both</i> cases, the facts, so far as I can see,<span class="pagenum"><a name="Page_108" id="Page_108">[Pg 108]</a></span> +entirely abolish the suggestion. For they prove that +even when epilepsy is produced in the parents under +circumstances which render "it obvious that the +presence of microbes can have nothing to do with +such an attack," the epileptiform condition is notwithstanding +transmitted to the progeny. What, +then, is gained by retaining the intrinsically improbable +hypothesis of microbes to explain the fact +of transmission "in Brown-Séquard's experiments," +when this very same fact is proved to occur without +the possibility of microbes "in Westphal's case"?</p> + +<p>The only other objection with regard to the seeming +transmission of traumatic epilepsy which Weismann +has advanced is, that such epilepsy may be produced +by two or three very different operations—viz. division +of the sciatic nerves (one or both), an injury to the +spinal cord, and a stroke on the head. Does not +this show, it is asked, that the epileptic condition +of guinea-pigs is due to a generally unstable condition +of the whole nervous system and is not associated +with any particular part thereof? Well, supposing +that such is the case, what would it amount to? +I cannot see that it would in any way affect the +only question in debate—viz. What is the significance +of the fact that epilepsy is <i>transmitted</i>? Even if it +be but "a tendency," "a disposition," or "a diathesis" +that is transmitted, it is none the less a case of +transmission, in fact quite as much so as if the pathological +state were dependent on the impaired condition +of any particular nerve-centre. For, it must be +observed, there can be no question that it is always +produced by an operation of <i>some</i> kind. If it were +ever to originate in guinea-pigs spontaneously, there<span class="pagenum"><a name="Page_109" id="Page_109">[Pg 109]</a></span> +might be some room for supposing that its transmission +is due to a congenital tendency running +through the whole species—although even then it +would remain unaccountable, on the ultra-Darwinian +view, why this tendency should be congenitally +<i>increased</i> by means of an operation. But epilepsy +does not originate spontaneously in guinea-pigs; +and therefore the criticism in question appears to me +irrelevant.</p> + +<p>Again, it may be worth while to remark that +Brown-Séquard's experiments do not disprove the +possibility of its being some one nerve-centre which +is concerned in all cases of traumatic epilepsy. And +this possibility becomes, I think, a probability in view +of Luciani's recent experiments on the dog. These +show that the epileptic condition can be produced +in this animal by injury to the cortical substance +of the hemispheres, and is then transmitted to progeny<a name="FNanchor_68_68" id="FNanchor_68_68"></a><a href="#Footnote_68_68" class="fnanchor">[68]</a>. +These experiments, therefore, are of great +interest—first, as showing that traumatic and transmissible +epilepsy is not confined to guinea-pigs; +and next, as indicating that the pathological state +in question is associated with the highest nerve-centres, +which may therefore well be affected by +injury to the lower centres, or even by section of a +large nerve trunk.</p> + +<p>So much, then, with regard to the case of transmitted +epilepsy. But now it must be noted that, +even if Weismann's suggestion touching microbes +were fully adequate to meet this case, it would still +leave unaffected those of transmitted protrusion of +the eye, drooping of the eyelid, gangrene of the<span class="pagenum"><a name="Page_110" id="Page_110">[Pg 110]</a></span> +ear, absence of toes, &c. In all these cases the facts, +as stated by Brown-Séquard, are plainly unamenable +to any explanation which would suppose them due +to microbes, or even to any general neurotic condition +induced by the operation. They are much too +definite, peculiar, and localized. Doubtless it is on +this account that the school of Weismann has not +seriously attempted to deal with them, but merely +recommends their repetition by other physiologists<a name="FNanchor_69_69" id="FNanchor_69_69"></a><a href="#Footnote_69_69" class="fnanchor">[69]</a>. +Certain criticisms, however, have been urged by +Weismann against the <i>interpretation</i> of Brown-Séquard's +facts as evidence in favour of the transmission +of acquired characters. It does not appear +to me that these criticisms present much weight; +but it is only fair that we should here briefly consider +them<a name="FNanchor_70_70" id="FNanchor_70_70"></a><a href="#Footnote_70_70" class="fnanchor">[70]</a>.</p> + +<p>First, with regard to Brown-Séquard's results other +than the production of transmitted epilepsy, Weismann +allows that the hypothesis of microbes can scarcely +apply. In order to meet these results, therefore, he +furnishes another suggestion—viz. that where the +nervous system has sustained "a great shock," the +animals are very likely to bear "weak descendants, +and such as are readily affected by disease." Then, in +answer to the obvious consideration, "that this does +not explain why the offspring should suffer from the +same disease" as that which has been produced +in the parents, he adds—"But this does not appear +to have been by any means invariably the case.<span class="pagenum"><a name="Page_111" id="Page_111">[Pg 111]</a></span> +For 'Brown-Séquard himself says, the changes in +the eye of the offspring were of a very variable +nature, and were only occasionally exactly similar +to those observed in the parents.'"</p> + +<p>Now, this does not appear to me a good commentary. +In the first place, it does not apply to +the other cases (such as the ears and the toes), +where the changes in the offspring, when they +occurred at all, <i>were</i> exactly similar to those observed +in the parents, save that some of them occasionally +occurred on the <i>opposite</i> side, and frequently also on +<i>both</i> sides of the offspring. These subordinate facts, +however, will not be regarded by any physiologist +as making against the more ready interpretation of +the results as due to heredity. For a physiologist well +knows that homologous parts are apt to exhibit +correlated variability—and this especially where variations +of a congenital kind are concerned, and also +where there is any reason to suppose that the nervous +system is involved. Moreover, even in the case of +the eye, it was always protrusion that was caused in +the parent and transmitted to the offspring as a result +of injuring the restiform bodies of the former; while +it was always partial closure of the eyelids that was +caused and transmitted by section of the sympathetic +nerve, or removal of the cervical ganglia. Therefore, if +we call such effects "diseases," surely it <i>was</i> "the same +disease" which in each case appeared in the parents +and reappeared in their offspring. Again, the "diseases" +were so peculiar, definite, and localized, that +I cannot see how they can be reasonably ascribed +to a general nervous "shock." Why, for instance, +if this were the case, should a protruding eye never<span class="pagenum"><a name="Page_112" id="Page_112">[Pg 112]</a></span> +result from removal of the cervical ganglia, a drooping +eyelid from a puncture of the restiform body, +a toeless foot from either or both of these operations, +and so on? In view of such considerations I +cannot deem these suggestions touching "microbes" +and "diseases" as worthy of the distinguished +biologist from whom they emanate.</p> + +<p>Secondly, Weismann asks—How can we suppose +these results to be instances of the transmission of +acquired characters, when from Brown-Séquard's own +statement of them it appears that the mutilation +itself was not inherited, but only its effects? Neither +in the case of the sciatic nerve, the sympathetic nerve, +the cervical ganglion, nor the restiform bodies, was +there ever any trace of transmitted injury in the +corresponding parts of the offspring; so that, if the +"diseases" from which they suffered be regarded as +hereditary, we have to suppose that a consequence +was in each case transmitted without the transmission +of its cause, which is absurd. But I do not think +that this criticism can be deemed of much weight +by a physiologist as distinguished from a naturalist. +For nothing is more certain to a student of physiology, +in any of its branches, than that negative evidence, if +yielded by the microscope alone, is most precarious. +Therefore it does not need a <i>visible</i> change in the +nervous system to be present, in order that the part +affected should be functionally weak or incapable: +pathology can show numberless cases of nerve-disorder +the "structural" causes of which neither +the scalpel nor the microscope can detect. So that, +if any peculiar form of nerve-disorder is transmitted +to progeny, and if it be certain that it has been<span class="pagenum"><a name="Page_113" id="Page_113">[Pg 113]</a></span> +caused by injury to some particular part of the +nervous system, I cannot see that there is any +reason to doubt the transmission of a nervous lesion +merely on the ground that it is not visibly discernible. +Of course there may be other grounds for doubting +it; but I am satisfied that this ground is untenable. +Besides, it must be remembered, as regards the +particular cases in question, that no one has thus far +investigated the histology of the matter by the greatly +improved methods which are now at our disposal.</p> + +<hr class="tb" /> + +<p>I have now considered all the criticisms which +have been advanced against what may be called +the Lamarckian interpretation of Brown-Séquard's +results; and I think it will be seen that they present +very little force—even if it can be seen that they +present any force at all. But it must be remembered +that this is a different thing from saying that the +Lamarckian interpretation is the true one. The +facts alleged are, without question, highly peculiar; +and, on this account alone, Brown-Séquard's interpretation +of them ought to be deemed provisional. +Hence, although as yet they have not encountered +any valid criticism from the side of ultra-Darwinian +theory, I do not agree with Darwin that, on the supposition +of their truth as facts, they furnish positive +proof of the transmission of acquired characters. +Rather do I agree with Weismann that further investigation +is needed in order to establish such an +important conclusion on the basis of so unusual a +class of facts. This further investigation, therefore, +I have undertaken, and will now state the results.</p> + +<p>Although this work was begun over twenty years<span class="pagenum"><a name="Page_114" id="Page_114">[Pg 114]</a></span> +ago, and then yielded negative results, it was only +within the last decade that I resumed it more systematically, +and under the tutelage of Brown-Séquard +himself. During the last two years, however, the +experiments have been so much interrupted by illness +that even now the research is far from complete. +Therefore I will here confine myself to a tabular +statement of the results as far as they have hitherto +gone, on the understanding that, in so far as they +are negative or doubtful, I am not yet prepared to +announce them as final.</p> + +<p>We may take Brown-Séquard's propositions in his +own order, as already given on page <a href="#Page_104">104</a>.</p> + +<blockquote><p>1st. Appearance of epilepsy in animals born of parents which +had been rendered epileptic by an injury to the spinal cord.</p> + +<p>2nd. Appearance of epilepsy also in animals born of parents +which had been rendered epileptic by section of the sciatic nerve.</p></blockquote> + +<p>I did not repeat these experiments with a view +to producing epilepsy, because, as above stated, they +had been already and sufficiently corroborated in +this respect. But I repeated many times the experiments +of dividing the sciatic nerve for the purpose of +testing the statements made later on in paragraphs +7 and 8, and observed that it almost always had +the effect of producing epilepsy in the animal thus +operated upon—and this of a peculiar kind, the chief +characteristics of which may here be summarized. +The epileptiform habit does not supervene until +some considerable time after the operation; it is +then transitory, lasting only for some weeks or +months. While the habit endures the fits never +occur spontaneously, but only as a result of irritating +a small area of skin behind the ear on the same side of<span class="pagenum"><a name="Page_115" id="Page_115">[Pg 115]</a></span> +the body as that on which the sciatic nerve had been +divided. Effectual irritation may be either mechanical +(such as gentle pinching), electrical, or, though +less certainly, thermal. The area of skin in question, +soon after the epileptiform habit supervenes, and +during all the time that it lasts, swarms with lice +of the kind which infest guinea-pigs—i.e. the lice +congregate in this area, on account, I think, of the +animal being there insensitive, and therefore not +disturbing its parasites in that particular spot; otherwise +it would presumably throw itself into fits +by scratching that spot. On removing the skin from +the area in question, no kind or degree of irritation +supplied to the subjacent tissue has any effect in producing +a fit. A fit never lasts for more than a very +few minutes, during which the animal is unconscious +and convulsed, though not with any great violence. The +epileptiform habit is but rarely transmitted to progeny. +Most of these observations are in accordance with +those previously made by Brown-Séquard, and also +by others who have repeated his experiments under +this heading. I can have no doubt that the injury +of the sciatic nerve or spinal cord produces a change +in some of the cerebral centres, and that it is +this change—whatever it is and in whatever part +of the brain it takes place—which causes the remarkable +phenomena in question.</p> + +<blockquote><p>3rd. A change in the shape of the ear in animals born of +parents in which such a change was the effect of a division +of the cervical sympathetic nerve.</p> + +<p>4th. Partial closure of the eyelids in animals born of parents +in which that state of the eyelids had been caused either by +section of the cervical sympathetic nerve, or the removal of the +superior cervical ganglion.</p></blockquote><p><span class="pagenum"><a name="Page_116" id="Page_116">[Pg 116]</a></span></p> + +<p>I have not succeeded in corroborating these results. +It must be added, however, that up to the time of +going to press my experiments on this, the easiest +branch of the research, have been too few fairly to +prove a negative.</p> + +<blockquote><p>5th. Exophthalmia in animals born of parents in which an +injury to the restiform body had produced that protrusion of the +eyeball.... In these animals, modified by heredity, the two +eyes generally protruded, although in the parents usually only +one showed exophthalmia, the lesion having been made in most +cases only on one of the corpora restiformia.</p></blockquote> + +<p>I have fully corroborated the statement that +injury to a particular spot of the restiform body is +quickly followed by a marked protrusion of the eyeball +on the same side. I have also had many cases +in which some of the progeny of parents thus affected +have shown considerable protrusion of the eyeballs on +both sides, and this seemingly abnormal protrusion +has been occasionally transmitted to the next generation. +Nevertheless, I am far from satisfied that +this latter fact is anything more than an accidental +coincidence. For I have never seen the so-called exophthalmia +of progeny exhibited in so high a degree +as it occurs in the parents as an immediate result +of the operation, while, on examining any large +stock of normal guinea-pigs, there is found a considerable +amount of individual variation in regard +to prominence of eyeballs. Therefore, while not +denying that the obviously abnormal amount of +protrusion due to the operation may be inherited +in lesser degrees, and thus may be the cause of the +unusual degree of prominence which is sometimes +seen in the eyeballs of progeny born of exophthalmic<span class="pagenum"><a name="Page_117" id="Page_117">[Pg 117]</a></span> +parents, I am unable to affirm so important a conclusion +on the basis supplied by these experiments.</p> + +<blockquote><p>6th. Haematoma and dry gangrene of the ears in animals +born of parents in which these ear-alterations had been caused +by an injury to the restiform body.</p></blockquote> + +<p>As regards the animals operated upon (i. e. the +parents), I find that the haematoma and dry gangrene +may supervene either several weeks after the +operation, or at any subsequent time up to many +months. When it does supervene it usually affects +the upper parts of both ears, and may then eat its +way down until, in extreme cases, it has entirely +consumed two-thirds of the tissue of both ears. +As regards the progeny of animals thus affected, +in some cases, but by no means in all, a similarly +morbid state of the ears may arise apparently +at any time in the life-history of the individual. +But I have observed that in cases where two or +more individuals <i>of the same litter</i> develop this +diseased condition, they usually do so at about the +same time—even though this be many months after +birth, and therefore after the animals are fully grown. +But in progeny the morbid process never goes so +far as in the parents which have been operated +upon, and it almost always affects the <i>middle</i> thirds +of the ears. In order to illustrate these points, reproductions +of two of my photographs are appended. +They represent the consequences of the operation on +a male and a female guinea-pig. Among the progeny +of both these animals there were several in which +a portion of each ear was consumed by apparently the +same process, where, of course, there had been no +operation.</p> +<p class="pagenum"><a name="Page_118" id="Page_118">[Pg 118]</a></p> + +<div class="figcenter" style="width: 303px;"> +<img src="images/illus_130.jpg" width="303" height="600" alt="Fig. 1.—Reproduction of photographs from life of a male and female +guinea-pig, whose left restiform bodies had been injured by a scalpel +six months previously. The loss of tissue in both ears was due to +haematoma and dry gangrene, which, however, had ceased when the +photograph was taken." title="Fig. 1.—Reproduction of photographs from life of a male and female +guinea-pig, whose left restiform bodies had been injured by a scalpel +six months previously. The loss of tissue in both ears was due to +haematoma and dry gangrene, which, however, had ceased when the +photograph was taken." /> +<span class="caption"><span class="smcap">Fig. 1.</span>—Reproduction of photographs from life of a male and female +guinea-pig, whose left restiform bodies had been injured by a scalpel +six months previously. The loss of tissue in both ears was due to +haematoma and dry gangrene, which, however, had ceased when the +photograph was taken.</span> +</div> + +<p><span class="pagenum"><a name="Page_119" id="Page_119">[Pg 119]</a></span>It should be observed that not only is a different <i>part</i> +of the ear affected in the progeny, but also a very +much less <i>quantity</i> thereof. Naturally, therefore, the +hypothesis of heredity seems less probable than that +of mere coincidence on the one hand, or of transmitted +microbes on the other. But I hope to have fairly +excluded both these alternative explanations. For, +as regards merely accidental coincidence, I have +never seen this very peculiar morbid process in the ears, +or in any other parts, of guinea-pigs which have +neither themselves had their restiform bodies injured, +nor been born of parents thus mutilated. As +regards the hypothesis of microbes, I have tried to +inoculate the corresponding parts of the ears of +normal guinea-pigs, by first scarifying those parts +and then rubbing them with the diseased surfaces of +the ears of mutilated guinea-pigs; but have not been +able in this way to communicate the disease.</p> + +<p>It will be seen that the above results in large +measure corroborate the statements of Brown-Séquard; +and it is only fair to add that he told me +they are the results which he had himself obtained +most frequently, but that he had also met with many +cases where the diseased condition of the ears in +parents affected the same parts in their progeny, and +also occurred in more equal degrees. Lastly, I should +like to remark, with regard to these experiments on +restiform bodies, and for the benefit of any one else who +may hereafter repeat them, that it will be necessary +for him to obtain precise information touching the +<i>modus operandi</i>. For it is only one very localized +spot in each restiform body which has to be injured in +order to produce any of the results in question.<span class="pagenum"><a name="Page_120" id="Page_120">[Pg 120]</a></span> +I myself lost two years of work on account of not +knowing this exact spot before going to Paris for the +purpose of seeing Brown-Séquard himself perform +the operation. I had in the preceding year seen one +of his assistants do so, but this gentleman had a much +more careless method, and one which in my hands +yielded uniformly negative results. The exact spot +in question in the restiform body is as far forwards as +it is possible to reach, and as far down in depth as is +compatible with not producing rotatory movements.</p> + +<blockquote><p>7th. Absence of two toes out of the three of the hind leg, and +sometimes of the three, in animals whose parents had eaten up +their hind-leg toes which had become anaesthetic from a section +of the sciatic nerve alone, or of that nerve and also of the crural. +Sometimes, instead of complete absence of the toes, only a part +of one or two or three was missing in the young, although in the +parent not only the toes but the whole foot were absent.</p></blockquote> + +<p>As I found that the results here described were +usually given by division of the sciatic nerve alone—or, +more correctly, by excision of a considerable portion +of the nerve, in order to prevent regeneration—I +did not also divide the crural. But, although I have +bred numerous litters from parents thus injured, there +has been no case of any inherited deficiency of toes. +My experiments in this connexion were carried on +through a series of six successive generations, so as to +produce, if possible, a cumulative effect. Nevertheless, +no effect of any kind was produced. On the other +hand, Brown-Séquard informed me that he had +observed this inherited absence of toes only in about +one or two per cent. of cases. Hence it is possible +enough, that my experiments have not been +sufficiently numerous to furnish a case. It may be<span class="pagenum"><a name="Page_121" id="Page_121">[Pg 121]</a></span> +added that there is here no measurable possibility +of accidental coincidence (seeing that normal guinea-pigs +do not seem ever to produce young with any +deficiency of toes), while the only possibility of +mal-observation consists in some error with regard +to the isolation (or the tabulation) of parents and +progeny. Such an error, however, may easily arise. +For gangrene of the toes does not set in till some +considerable time after division of the sciatic nerve. +Hence, if the wound be healed before the gangrene +begins, and if any mistake has been made with regard +to the isolation (or tabulation) of the animal, it +becomes possible that the latter should be recorded +as an uninjured, instead of an injured, individual. On +this account one would like to be assured that +Brown-Séquard took the precaution of examining +the state of the sciatic nerve in those comparatively +few specimens which he alleges to have displayed +such exceedingly definite proof of the inheritance +of a mutilation. For it is needless to remark, after +what has been said in the preceding chapter on the +analogous case of epilepsy, that the proof would +not be regarded by any physiologist as displaced +by the fact that there is no observable deficiency +in the sciatic nerve of the toeless young.</p> + +<blockquote><p>8th. Appearance of various morbid states of the skin and +hair of the neck and face in animals born of parents having had +similar alterations in the same parts, as effects of an injury to +the sciatic nerve.</p></blockquote> + +<p>I have not paid any attention to this paragraph, +because the facts which it alleges did not seem of +a sufficiently definite character to serve as a guide to +further experiment.</p> + +<p><span class="pagenum"><a name="Page_122" id="Page_122">[Pg 122]</a></span>On the whole, then, as regards Brown-Séquard's +experiments, it will be seen that I have not been +able to furnish any approach to a full corroboration. +But I must repeat that my own experiments have +not as yet been sufficiently numerous to justify +me in repudiating those of his statements which +I have not been able to verify.</p> + +<p>The only other experimental results, where animals +are concerned, which seemed to tell on the side of +Lamarckianism, are those of Mr. Cunningham, already +alluded to. But, as the research is still in progress, +the school of Weismann may fairly say that it would +be premature to discuss its theoretical bearings.</p> + +<hr class="tb" /> + +<p>Passing now from experiments on animals to +experiments on plants, I must again ask it to be +borne in mind, that here also no researches have +been published, which have had for their object the +testing of the question on which we are engaged. +As in the case of animals, therefore, so in that of +plants, we are dependent for any experimental results +bearing upon the subject to such as have been gained +incidentally during the course of investigations in +quite other directions.</p> + +<p>Allusion has already been made, in my previous +essay, to De Vries' observations on the chromatophores +of algae passing from the ovum of the mother to +the daughter organism; and we have seen that +even Weismann admits, "It appears possible that +a transmission of somatogenetic variation has here +occurred<a name="FNanchor_71_71" id="FNanchor_71_71"></a><a href="#Footnote_71_71" class="fnanchor">[71]</a>." It will now be my object to show that +such variations appear to be sometimes transmitted<span class="pagenum"><a name="Page_123" id="Page_123">[Pg 123]</a></span> +in the case of higher plants, and this under circumstances +which carry much less equivocal evidence +of the inheritance of acquired characters, than can +be rendered by the much more simple organization +of an alga.</p> + +<p>I have previously mentioned Hoffmann's experiments +on transplantation, the result of which was +to show that variations, directly induced by changed +conditions of life, were reproduced by seed<a name="FNanchor_72_72" id="FNanchor_72_72"></a><a href="#Footnote_72_72" class="fnanchor">[72]</a>. Weismann, +however, as we have seen, questions the +<i>somatogenetic</i> origin of these variations—attributing +the facts to a <i>blastogenetic</i> change produced in the +plants by a direct action of the changed conditions +upon the germ-plasm itself<a name="FNanchor_73_73" id="FNanchor_73_73"></a><a href="#Footnote_73_73" class="fnanchor">[73]</a>. And he points out +that whether he is right or wrong in this interpretation +can only be settled by ascertaining whether +the observable somatic changes occur in the generation +which is first exposed to the changed conditions +of life. If they do occur in the first generation, they +are somatogenetic changes, which afterwards <span class="correction" title="Transcriber's Note: 're-act' in the text.">react</span> +on the substance of heredity, so as to transmit the +acquired peculiarities to progeny. But if they do +not occur till the second (or any later) generation, +they are presumably blastogenetic. Unfortunately +Hoffmann does not appear to have attended to +this point with sufficient care, but there are other +experiments of the same kind where the point has +been specially observed.</p> + +<p>For instance, M. L. A. Carrière<a name="FNanchor_74_74" id="FNanchor_74_74"></a><a href="#Footnote_74_74" class="fnanchor">[74]</a> gathered seed from +the wild radish (<i>Raphanus Raphanistrum</i>) in France,<span class="pagenum"><a name="Page_124" id="Page_124">[Pg 124]</a></span> +and sowed one lot in the light dry soil near the +Museum of Natural History in Paris, while another +lot was sown by him at the same time in heavy +soil elsewhere. His object was to ascertain whether +he could produce a good cultivated radish by +methodical selection; and this he did; in a wonderfully +rapid manner, during the course of a very few +generations. But the point for us is, that <i>from the +first</i> the plants grown in the light soil of Paris +presented sundry marked differences from those +grown in the heavy soil of the country; and that +these points of difference had nothing to do with +the variations on which his artificial selection was +brought to bear. For while his artificial selection +was directed to increasing the <i>size</i> of the "root," +the differences in question had reference to its <i>form</i> +and <i>colour</i>. In Paris an elongated form prevailed, +which presented either a white or a rose colour: in +the country the form was more rounded, and the +colour violet, dark brown, or "almost black." Now, +as these differences were strongly apparent in the +first generation, and were not afterwards made the +subject of selection, both in origin and development +they must have been due to "climatic" influences +acting on the somatic tissues. And although the author +does not appear to have tested their hereditary characters +by afterwards sowing the seed from the Paris +variety in the country, or <i>vice versa</i>, we may +fairly conclude that these changes must have been +hereditary—1st, from the fact of their intensification +in the course of the five sequent generations over +which the experiment extended, and, 2nd, from the +very analogous results which were similarly obtained<span class="pagenum"><a name="Page_125" id="Page_125">[Pg 125]</a></span> +in the following case with another genus, where +both the somatogenetic and the hereditary characters +of the change were carefully and specially observed. +This case is as follows.</p> + +<p>The late Professor James Buckman, F.R.S., saved +some seed from wild parsnips (<i>P. sativa</i>) in the +summer of 1847, and sowed under changed conditions +of life in the spring of 1848. The plants grown +from these wild seeds were for the most part like +wild plants; but some of them had "already +(i.e. in the autumn of 1848) the light green and +smooth aspect devoid of hairs which is peculiar to +the cultivated plant; and among the latter there +were a few with longer leaves and broader divisions +of leaf-lobes than the rest—the leaves, too, all growing +systematically round one central bud. The roots +of the plant when taken up were observed to be +for the most part more fleshy than those of wild +examples<a name="FNanchor_75_75" id="FNanchor_75_75"></a><a href="#Footnote_75_75" class="fnanchor">[75]</a>."</p> + +<p>Professor Buckman then proceeds to describe how +he selected the best samples for cultivation in +succeeding generations, till eventually the variety +which he called "The Student" was produced, and +which Messrs. Sutton still regard as the best variety +in their catalogue. That is to say, it has come +true to seed for the last forty years; and although +such great excellence and stability are doubtless in +chief part due to the subsequent process of selection +by Professor Buckman in the years 1848-1850, +this does not affect the point with which we are +here concerned—namely, that the somatogenetic +changes of the plants in the first generation were<span class="pagenum"><a name="Page_126" id="Page_126">[Pg 126]</a></span> +transmitted by seed to the second generation, +and thus furnished Professor Buckman with the +material for his subsequent process of selection. +And the changes in question were not merely of +a very definite character, but also of what may be +termed a very <i>local</i> character—affecting only particular +tissues of the soma, and therefore expressive +of a high degree of <i>representation</i> on the part of the +subsequently developed seed, by which they were +faithfully reproduced in the next generation.</p> + +<p>Here is another case. M. Lesage examined the +tissues of a large number of plants growing both +near to, and remote from, the sea. He suspected +that the characteristic fleshiness, &c. of seaside plants +was due to the influence of sea-salt; and proved that +such was the case by causing the characters to +occur in inland plants as a result of watering them +with salt-water. Then he adds:—</p> + +<blockquote><p>"J'ai réussi surtout pour le <i>Lepidium sativum</i> cultivé en +1888; j'ai obtenu pour la même plante des résultats plus nets +encore dans la culture de 1889, entreprise en semant les graines +récoltées avec soin des pots de l'année précédente et traitées +exactement de la même façon<a name="FNanchor_76_76" id="FNanchor_76_76"></a><a href="#Footnote_76_76" class="fnanchor">[76]</a>."</p></blockquote> + +<p>Here, it will be observed, there was no selection; +and therefore the increased hereditary effect +in the second generation must apparently be ascribed +to a continuance of influence exercised by somatic +tissues on germinal elements; for at the time when +the changes were produced no seed had been formed. +In other words, the accumulated change, like the +initial change, would seem to have been exclusively +of somatogenetic origin; and yet it so influenced the<span class="pagenum"><a name="Page_127" id="Page_127">[Pg 127]</a></span> +qualities of the seed (as this was afterwards formed), +that the augmented changes were transmitted to the +next generation, part for part, as the lesser changes had +occurred in the preceding generation. "This experiment, +therefore, like Professor Buckman's, shows that +the alteration of the tissues was carried on in the +second generation from the point gained in the first. +In both cases no germ-plasm (in the germ-cells) +existed at the time during which the alterations +arose, as they were confined to the vegetative system; +and in the case of the parsnips and carrots, being +biennials no germ-cells are produced till the second +year has arrived<a name="FNanchor_77_77" id="FNanchor_77_77"></a><a href="#Footnote_77_77" class="fnanchor">[77]</a>."</p> + +<p>Once more, Professor Bailey remarks:—</p> + +<blockquote><p>"Squashes often show remarkable differences when grown +upon different soils; and these differences can sometimes be perpetuated +for a time by seeds. The writer has produced, from +the same parent, squashes so dissimilar, through the simple +agency of a change of soil in one season, that they might readily +be taken for distinct varieties. Peas are known to vary in the +same manner. The seeds of a row of peas of the same kind, +last year gave the writer marked variations due to differences +of soil.... Pea-growers characterize soils as 'good' and +'viney.' Upon the latter sort the plants run to vine at the +expense of the fruit, and their offspring for two or three +generations have the same tendency<a name="FNanchor_78_78" id="FNanchor_78_78"></a><a href="#Footnote_78_78" class="fnanchor">[78]</a>."</p></blockquote> + +<p>I think these several cases are enough to show +that, while the Weismannian assumption as to the +seeming transmission of somatogenetic characters +being restricted to the lowest kinds of plants is<span class="pagenum"><a name="Page_128" id="Page_128">[Pg 128]</a></span> +purely gratuitous, there is no small amount of +evidence to the contrary—or evidence which seems +to prove that a similar transmission occurs likewise +in the higher plants. And no doubt many additional +cases might be advanced by any one who is well +read in the literature of economic botany.</p> + +<p>It appears to me that the only answer to such cases +would be furnished by supposing that the hereditary +changes are due to an alteration of the residual +"germ-plasm" in the wild seed, when this is first +exposed to the changed conditions of life, due to +its growth in a strange kind of soil—e.g. while germinating +in an unusual kind of earth for producing the +first generation. But this would be going a long +way to save an hypothesis. In case, however, it +should now be suggested, I may remark that it +would be negatived by the following facts.<a name="FNanchor_79_79" id="FNanchor_79_79"></a><a href="#Footnote_79_79" class="fnanchor">[79]</a></p> + +<p>In the first place, an endless number of cases might +be quoted where somatogenetic changes thus produced +by changed conditions of life are not hereditary. +Therefore, in all these cases it is certainly not the +"germ-plasm" that is affected. In other words, there +can be no question that somatogenetic changes of the +kinds above mentioned do very readily admit of being +produced in the first generation by changes of soil, +altitude, &c. And that somatogenetic changes thus +produced should not always—or even generally—prove +themselves to be hereditary from the first +moment of their occurrence, is no more than any theory<span class="pagenum"><a name="Page_129" id="Page_129">[Pg 129]</a></span> +of heredity would expect. Indeed, looking to the +known potency of reversion, the wonder is that in any +case such changes should become hereditary in a single +generation. On the other hand, there is no reason to +imagine that the hypothetical germ-plasm—howsoever +<i>unstable</i> we may suppose it to be—can admit of being +directly affected by a change of soil in a single +generation. For, on this view, it must presumably be +chiefly affected during the short time that the seed is +germinating; and during that time the changed conditions +can scarcely be conceived as having any points +of attack, so to speak, upon the residual germ-plasm. +There are no roots on which the change of <i>soil</i> can +make itself perceptible, nor any stem and leaves on +which the change of <i>atmosphere</i> can operate. Yet the +changed condition's may produce hereditary modifications +in any parts of the plant, which are not only +precisely analogous to non-hereditary changes similarly +produced in the somatic tissues of innumerable other +plants, but are always of precisely the same kind in +the same lot of plants that are affected. When all the +radishes grown from wild seed in Paris, for instance, +varied in the direction of rotundity and dark colour, +while those grown in the country presented the opposite +characters, we can well understand the facts as due +to an entire season's action upon the whole of the +growing plant, with the result that all the changes +produced in each set of plants were similar—just as +in the cases where similarly "climatic" modifications +are not hereditary, and therefore unquestionably due +to changed conditions acting on roots, stems, leaves, +or flowers, as the case may be. On the other hand, +it is not thus intelligible that during the short<span class="pagenum"><a name="Page_130" id="Page_130">[Pg 130]</a></span> +time of germination the changed conditions should +effect a re-shuffling (or any other modification) of +the "germ-plasm" in the seeds—and this in such +a manner that the effect on the residual germ-plasm +reserved for future generations is precisely similar to +that produced on the somatic tissues of the developing +embryo.</p> + +<p>In the second place, as we have seen, in some of +the foregoing cases the changes were produced +months—and even years—before the seeds of the first +germination were formed. Therefore the hereditary +effect, if subsequent to the period of embryonic germination, +must have been produced on germ-plasm +as this occurs diffused through the somatic tissues. +But, if so, we shall have to suppose that such germ-plasm +is afterwards gathered in the seeds when these +are subsequently formed. This supposition, however, +would be radically opposed to Weismann's theory of +heredity: nor do I know of any other theory with +which it would be reconcilable, save such as entertain +the possibility of the Lamarckian factors.</p> + +<p>Lastly, in the third place, I deem the following +considerations of the highest importance:—</p> + +<blockquote><p>"As other instances in which peculiar structures are now +hereditary may be mentioned aquatic plants and those producing +subterraneous stems. Whether they be dicotyledons or monocotyledons, +there is a fundamental agreement in the anatomy +of the roots and stem of aquatic plants, and, in many cases, of +the leaves as well. Such has hitherto been attributed to the +aquatic habit. The inference or deduction was, of course, based +upon innumerable coincidences; the water being supposed to +be the direct cause of the degenerate structures, which are +hereditary and characteristic of such plants in the wild state. +M. Costantin has, however, verified this deduction, by making<span class="pagenum"><a name="Page_131" id="Page_131">[Pg 131]</a></span> +terrestrial and aerial stems to grow underground and in water: +the structures <i>at once</i> began to assume the subterranean or +aquatic type, as the case might be; and, conversely, aquatic +plants made to grow upon land <i>at once</i> began to assume the +terrestrial type of structure, while analogous results followed +changes from a subterranean to an aerial position, and <i>vice +versa</i>."</p></blockquote> + +<p>This is also quoted from the Rev. Prof. Henslow's +letters to me, and the important point in it is, that +the great changes in question are proved to be of +a purely "somatogenetic" kind; for they occurred "at +once" <i>in the ready-grown plant</i>, when the organs +concerned were exposed to the change from aquatic +to terrestrial life, or <i>vice versa</i>—and also from a subterranean +to an aerial position, or <i>vice versa</i>. Consequently, +even the abstract possibility of the changed +conditions of life having operated on the <i>seed</i> is here +excluded. Yet the changes are of precisely the same +kind as are now <i>hereditary</i> in the wild species. It +thus appears undeniable that all these remarkable and +uniform changes must originally have been somatogenetic +changes; yet they have now become blastogenetic. +This much, I say, seems undeniable; and +therefore it goes a long way to prove that the non-blastogenetic +character of the changes has been due +to their originally somatogenetic character. For, if +not, how did natural selection ever get an opportunity +of making any of them blastogenetic, when every +individual plant has always presented them as already +given somatogenetically? This last consideration +appears in no small measure to justify the opinion of +Mr. Henslow, who concludes—"These experiments +prove, not only that the influence of the environment<span class="pagenum"><a name="Page_132" id="Page_132">[Pg 132]</a></span> +is <i>at once</i> felt by the organ; but that it is indubitably +the <i>cause</i> of the now specific and hereditary traits +peculiar to normally aquatic, subterranean, and +aerial stems, or roots<a name="FNanchor_80_80" id="FNanchor_80_80"></a><a href="#Footnote_80_80" class="fnanchor">[80]</a>."</p> + +<p>He continues to furnish other instances in the same +line of proof—such as the distinctive "habits" of +insectivorous, parasitic, and climbing plants; the +difference in structure between the upper and under +sides of horizontal leaves, &c. "For here, as in all +organs, we discover by experiment how easily the +anatomy of plants can be affected by their environment; +and that, as long as the latter is constant, so are +the characters of the plants constant and hereditary."</p> + +<blockquote><p>[The following letter, contributed by Dr. Hill to <i>Nature</i>, vol. I. p. 617, +may here be quoted. C. Ll. M.</p> + +<p>"It may be of interest to your readers to know that two guinea-pigs +were born at Oxford a day or two before the death Dr. Romanes, both +of which exhibited a well-marked droop of the left upper <span class="correction" title="Transcriber's Note: 'eye-lid' in the text.">eyelid</span>. These +guinea-pigs were the offspring of a male and a female guinea-pig in both +of which I had produced for Dr. Romanes, some months earlier, a droop +of the left upper eyelid by division of the left cervical sympathetic nerve. +This result is a corroboration of the series of Brown-Séquard's experiments +on the inheritance of acquired characteristics. A very large series +of such experiments are of course needed to eliminate all sources of error, +but this I unfortunately cannot carry out at present, owing to the need of +a special farm in the country, for the proper care and breeding of the +animals.—<span class="smcap">Leonard Hill.</span></p> + +<p>"Physiological Laboratory, Univ. Coll. London, Oct. 18, 1894."]</p></blockquote> +<hr class="chap" /> +<p class="pagenum"><a name="Page_133" id="Page_133">[Pg 133]</a></p> + + + + +<h2>CHAPTER V.<br /> +<span class="smcap">Characters as Hereditary and Acquired</span><br /> +(<i>continued</i>).</h2> + + +<h3>(A. and B.)<br /> +<i>Direct and Indirect Evidence in favour of the Non-inheritance +of Acquired Characters</i><a name="FNanchor_81_81" id="FNanchor_81_81"></a><a href="#Footnote_81_81" class="fnanchor">[81]</a>.</h3> + +<p>The strongest argument in favour of "continuity" +is that based upon the immense difference between +congenital and acquired characters in respect of +heritability. For that there is a great difference +in this respect is a matter of undeniable fact. And +it is obvious that this difference, the importance of +which must be allowed its full weight, is just what +we should expect on the theory of the continuity of +the germ-plasm, as opposed to that of pangenesis. +Indeed it may be said that the difference in question, +while it constitutes important <i>evidence</i> in favour of +the former theory, is a <i>difficulty</i> in the way of the +latter. But here two or three considerations must be +borne in mind.</p> + +<p>In the first place, this fact has long been one which +has met with wide recognition and now constitutes +the main ground on which the theory of continuity<span class="pagenum"><a name="Page_134" id="Page_134">[Pg 134]</a></span> +stands. That is to say, it was the previous knowledge +of this contrast between congenital and acquired +characters which led to the formulation of a theory of +continuity by Mr. Galton, and to its subsequent +development by Prof Weismann.</p> + +<p>But, in the second place, there is a wide difference +between the certainty of this fact and that of the +theory based upon it. The certain fact is, that +a great distinction in respect of heritability is +observable between congenital and acquired characters. +The theory, as formulated by Weismann, is +that the distinction is not only great but absolute, or, +in other words, that in no case and in no degree +can any acquired character be ever inherited. This +hypothesis, it will be observed, goes far beyond the +observed fact, for it is obviously possible that, notwithstanding +this great difference in regard to heritability +between congenital and acquired characters, +the latter may nevertheless, sometimes and in some +degree, be inherited, however much difficulty we may +experience in observing these lesser phenomena in +presence of the greater. The Weismannian hypothesis +of <i>absolute</i> continuity is one thing, while the +observed fact of at least a <i>high relative degree</i> of +continuity is quite another thing. And it is necessary +to be emphatic on this point, since some of the +reviewers of my <i>Examination of Weismannism</i> confound +these two things. Being apparently under the +impression that it was reserved for Weismann to +perceive the fact of there being a great difference +between the heritability of congenital and acquired +characters, they deem it inconsistent in me to +acknowledge this fact while at the same time<span class="pagenum"><a name="Page_135" id="Page_135">[Pg 135]</a></span> +questioning the hypothetical basis of his fundamental +postulate touching the absolute continuity of +germ-plasm. It is one merit of Galton's theory, as +against Weismann's, that it does not dogmatically +exclude the possible interruption of continuity on +some occasions and in some degree. Herein, indeed, +would seem to lie the central core of the whole +question in dispute. For it is certain and has long +been known that individually acquired characters +are at all events much less heritable than are long-inherited +or congenital ones. But Lamarckian theory +supposes that congenital characters were in some +cases originally acquired, and that what are now +blastogenetic characters were in some cases at first +somatogenetic and have become blastogenetic only +in virtue of sufficiently long inheritance. Since +Darwin's time, however, evolutionists (even of the +so-called Lamarckian type) have supposed that +natural selection greatly assists this process of determining +which somatogenetic characters shall become +congenital or blastogenetic. Hence all schools of +evolutionists are, and have long been, agreed in +regarding the continuity principle as true in the main. +No evolutionist would at any time have propounded +the view that one generation depends for <i>all</i> its +characters on those acquired by its <i>immediate</i> ancestors, +for this would merely be to unsay the theory of +Evolution itself, as well as to deny the patent facts +of heredity as shown, for example, in atavism. At +most only some fraction of a <i>per cent.</i> could be +supposed to do so. But Weismann's contention is +that this principle is not only true in the main, but +<i>absolutely</i> true; so that natural selection becomes all<span class="pagenum"><a name="Page_136" id="Page_136">[Pg 136]</a></span> +in all or not at all. Unless Weismannism be regarded +as this doctrine of absolutism it permits no basis for +his attempted theory of evolution.</p> + +<p>And, whatever may be said to the contrary by the +more enthusiastic followers of Prof. Weismann, I must +insist that there is the widest possible difference +between the truly scientific question of fact which is +assumed by Weismann as answered (the base-line of +the diagram on p. <a href="#Page_43">43</a>), and the elaborate structure +of deductive reasoning which he has reared on this +assumption (the Y-like structure). Even if the +assumption should ever admit of inductive proof, the +almost bewildering edifice of deductive reasoning +which he has built upon it would still appear to me to +present extremely little value of a scientific kind. Interesting +though it may be as a monument of ingenious +speculation hitherto unique in the history of science, +the mere flimsiness of its material must always prevent +its far-reaching conclusions from being worthy +of serious attention from a biological point of view. +But having already attempted to show fully in my +<i>Examination</i> this great distinction between the +scientific importance of the question which lies at the +base of "Weismannism," and that of the system which +he has constructed on his assumed answer thereto, +I need not now say anything further with regard to it.</p> + +<p>Again, on the present occasion and in this connexion +I should like to dissipate a misunderstanding into +which some of the reviewers of the work just mentioned +have fallen. They appear to have concluded +that because I have criticized unfavourably a considerable +number of Weismann's theories, I have +shown myself hostile to his entire system. Such,<span class="pagenum"><a name="Page_137" id="Page_137">[Pg 137]</a></span> +however, is by no means the case; and the misunderstanding +can only be accounted for by supposing +that the strongly partisan spirit which these +critics display on the side of neo-Darwinism has +rendered them incapable of appreciating any attempt +at impartial—or even so much as independent—criticism. +At all events, it is a matter of fact that +throughout the work in question I have been particularly +careful to avoid this misunderstanding as to +my own position. Over and over again it is there +stated that, far from having any objection to the +principle of "Continuity" as represented in the base-line +of the above diagram, I have been convinced +of its truth ever since reading Mr. Galton's <i>Theory +of Heredity</i> in 1875. All the "hard words" which +I have written against Weismann's system of theories +have reference to those parts of it which go to constitute +the Y-like structure of the diagram.</p> + +<p>It is, however, desirable to recur to another point, +and one which I hope will be borne in mind throughout +the following discussion. It has already been +stated, a few pages back, that the doctrine of continuity +admits of being held in two very different +significations. It may be held as absolute, or as +relative. In the former case we have the Weismannian +doctrine of germ-plasm: the substance of +heredity is taken to be a substance <i>per se</i>, which +has always occupied a separate "sphere" of its own, +without any contact with that of somatoplasm further +than is required for its lodgement and nutrition; +hence it can never have been in any degree modified +as to its hereditary qualities by use-inheritance +or any other kind of somatogenetic change; it has<span class="pagenum"><a name="Page_138" id="Page_138">[Pg 138]</a></span> +been <i>absolutely</i> continuous "since the first origin of +life." On the other hand, the doctrine of continuity +may be held in the widely different sense in which +it has been presented by Galton's theory of Stirp. +Here the doctrine is, that while for the most part +the phenomena of heredity are due to the continuity +of the substance of heredity through numberless +generations, this substance ("Stirp") is nevertheless +not absolutely continuous, but may admit, in small +though cumulative degrees, of modification by use-inheritance +and other factors of the Lamarckian kind. +Now this all-important distinction between these two +theories of continuity has been fully explained and +thoroughly discussed in my <i>Examination</i>; therefore +I will not here repeat myself further than to make +the following remarks.</p> + +<p>The Weismannian doctrine of continuity as absolute +(base-line of the diagram) is necessary for the +vast edifice of theories which he has raised upon it +(the Y), first as to the minute nature and exact +composition of the substance of heredity itself +("Germ-plasm"), next as to the precise mechanism +of its action in producing the visible phenomena of +heredity, variation, and all allied phenomena, and, +lastly, the elaborate and ever-changing theory of +organic evolution which is either founded on or +interwoven with this vast system of hypothetic +speculation. Galton's doctrine of continuity, on +the other hand, is a "Theory of Heredity," and +a theory of heredity alone. It does not meddle +with any other matters whatsoever, and rigidly +avoids all speculation further than is necessary for +the bare statement and inductive support of the<span class="pagenum"><a name="Page_139" id="Page_139">[Pg 139]</a></span> +doctrine in question. Hence, it would appear that +this, the only important respect wherein the doctrine +of continuity as held by Galton differs from +the doctrine as held by Weismann, arisen from the +necessity under which the latter finds himself of +postulating <i>absolute</i> continuity as a logical basis +for his deductive theory of the precise mechanism +of heredity on the one hand, and of his similarly +deductive theory of evolution on the other. So far +as the doctrine of continuity is itself concerned +(i.e. the question of the inheritance of acquired +characters), there is certainly no more inductive +reason for supposing the continuity absolute "since +the first origin of life," than there is for supposing +it to be more or less susceptible of interruption by +the Lamarckian factors. In other words, but for +the sake of constructing a speculative foundation +for the support of his further theories as to "the +architecture of germ-plasm" and the factors of +organic evolution, there is no reason why Weismann +should maintain the absolute separation of the +"sphere" of germ-plasm from that of somatoplasm. +On the contrary, he has no reason for concluding +against even a considerable and a frequent amount +of cutting, or overlapping, on the part of these two +spheres.</p> + +<p>But although this seems to me sufficiently obvious, +as I have shown at greater length in the <i>Examination +of Weismannism</i>, it must not be understood that +I hold that there is room for any large amount of +such overlapping. On the contrary, it appears to me +as certain as anything can well be that the amount +of such overlapping from one generation to another,<span class="pagenum"><a name="Page_140" id="Page_140">[Pg 140]</a></span> +if it ever occur at all, must be exceedingly small, +so that, if we have regard to only a few sequent +generations, the effects of use-inheritance, and Lamarckian +factors are, at all events as a rule, +demonstrably imperceptible. But this fact does not +constitute any evidence—as Weismann and his +followers seem to suppose—against a possibly important +influence being exercised by the Lamarckian +factors, in the way of gradual increments through +a long series of generations. It has long been well +known that acquired characters are at best far less +fully and far less certainly inherited than are congenital +ones. And this fact is of itself sufficient +to prove the doctrine of continuity to the extent +that even the Lamarckian is rationally bound to +concede. But the fact yields no proof—scarcely +indeed so much as a presumption—in favour of the +doctrine of continuity as absolute. For it is sufficiently +obvious that the adaptive work of heredity +could not be carried on at all if there had to be +a discontinuity in the substance of heredity at every +generation, or even after any very large number of +generations.</p> + +<p>Little more need be said concerning the arguments +which fall under the headings A and B. The +Indirect evidence is considered in Appendix I of the +<i>Examination of Weismannism</i>; while the Direct +evidence is considered in the text of that work in +treating of Professor Weismann's researches on the +<i>Hydromedusae</i> (pp. 71-76).</p> + +<p>The facts of karyokinesis are generally claimed +by the school of Weismann as making exclusively +in favour of continuity as absolute. But this is<span class="pagenum"><a name="Page_141" id="Page_141">[Pg 141]</a></span> +a partisan view to take. In any impartial survey +it should be seen that while the facts are fairly +interpretable on Weismann's theory, they are by +no means proof thereof. For any other theory of +Heredity must suppose the material of heredity to +be of a kind more or less specialized, and the +mechanism of heredity extremely precise and well +ordered. And this is all that the facts of karyokinesis +prove. Granting that they prove continuity, +they cannot be held to prove that continuity to +be absolute. In other words, the facts are by no +means incompatible with even a large amount of +commerce between germ-plasm and somato-plasm, or +a frequent transmission of acquired characters.</p> + +<p>Again, Weismann's theory, that the somatic and +the germ-plasm determinants may be similarly and +simultaneously modified by external conditions may +be extended much further than he has used it +himself, so as to exclude, or at any rate invalidate, +<i>all</i> evidence in favour of Lamarckianism, other than +the inheritance of the effects of use and disuse. All +evidence from apparently inherited effects produced +by change of external conditions is thus virtually +put out of court, leaving only evidence from the +apparently inherited effects of functionally produced +modifications. And this line of evidence is invalidated +by Panmixia. Hence there remain only the arguments +from selective value and co-adaptation. Weismann +meets these by adducing the case of neuter insects, +which have been already considered at sufficient +length.</p> +<p class="pagenum"><a name="Page_142" id="Page_142">[Pg 142]</a></p> + + +<h3>(C.)<br /> +<i>Experimental Evidence as to the Non-inheritance +of Acquired Characters.</i></h3> + +<p>Let us now proceed to the experimental evidence +which has been adduced on the side of Weismannism.</p> + +<p>Taking this evidence in order of date, we have +first to mention that on which the school of +Weismann has hitherto been satisfied almost exclusively +to rely. This is the line of negative +evidence, or the seeming absence of any experimental +demonstration of the inheritance of acquired characters. +This kind of evidence, however, presents +much less cogency than is usually supposed. And +it has been shown in the last chapter that the +amount of experimental evidence in favour of the +transmission of acquired characters is more considerable +than the school of Weismann seems to be +aware—especially in the vegetable kingdom. I do +not think that this negative line of evidence presents +much weight; and, to show that I am not biassed +in forming this judgement, I may here state that few +have more reason than myself for appreciating the +weight of such evidence. For, as already stated, +when first led to doubt the Lamarckian factors, now +more than twenty years ago, I undertook a research +upon the whole question—only a part of which was +devoted to testing the particular case of Brown-Séquard's +statements, with the result recorded in the +preceding chapter. As this research yielded negative +results in all its divisions—and, not only in the matter +of Brown-Séquard's statements—I have not hitherto<span class="pagenum"><a name="Page_143" id="Page_143">[Pg 143]</a></span> +published a word upon the subject. But it now +seems worth while to do so, and for the following +reasons.</p> + +<p>First, as just observed, a brief account of my old +experiences in this field will serve to show what good +reason I have for feeling the weight of such negative +evidence in favour of Continuity as arises from failure +to produce any good experimental evidence to the +contrary. In the second place, now that the question +has become one of world-wide interest, it would seem +that even negative results deserve to be published +for whatever they may be worth on the side of Neo-Darwinism. +Lastly, in the third place, although the +research yielded negative results in my hands, it is +perhaps not undesirable to state the nature of it, +if only to furnish suggestions to other physiologists, +in whose hands the experiments—especially in these +days of antiseptics—may lead to a different termination. +Altogether I made thousands of experiments +in graft-hydridization (comprising bines, bulbs of +various kinds, buds, and tubers); but with uniformly +negative results. With animals I tried a number of +experiments in grafting characteristic congenital tissues +from one variety on another—such as the combs of +Spanish cocks upon the heads of Hamburgs; also, +in mice and rats, the grafting together of different +varieties; and, in rabbits and bitches, the transplantation +of ovaries of newly-born individuals belonging +to different well-marked breeds. This latter experiment +seems to be one which, if successfully performed +(so that the transplanted ovaries would form their +attachment in a young bitch puppy and subsequently +yield progeny to a dog of the same breed as herself)<span class="pagenum"><a name="Page_144" id="Page_144">[Pg 144]</a></span> +would furnish a crucial test as to the inheritance or +non-inheritance of acquired characters. Therefore +I devoted to it a large share of my attention, and +tried the experiment in several different ways. But +I was never able to get the foreign ovary—or even any +portion thereof—to graft. Eventually the passing of +the Vivisection Act caused me to abandon the whole +research as far as animals were concerned—a research, +indeed, of which I had become heartily tired, since in +no one instance did I obtain any adhesion. During +the last few years, however, I have returned to these +experiments under a licence, and with antiseptic +precautions, but with a similar want of success. +Perhaps this prolonged and uniformly fruitless experience +may now have the effect of saving the time of +other physiologists, by warning them off the roads +where there seems to be no thoroughfare. On the +other hand, it may possibly lead some one else to +try some variation in the method, or in the material, +which has not occurred to me. In particular, I am +not without hope that the transplantation of ovaries +in very young animals may eventually prove to be +physiologically possible; and, if so, that the whole +issue as between the rival theories of heredity will +be settled by the result of a single experiment. +Possibly some of the invertebrata will be found to +furnish the suitable material, although I have been +unable to think of any of these which present +sufficiently well-marked varieties for the purpose. +But, pending the successful accomplishment of this +particular experiment in the grafting of any animal +tissue, I think it would be clearly unjustifiable to +conclude against the Lamarckian factors on the<span class="pagenum"><a name="Page_145" id="Page_145">[Pg 145]</a></span> +ground of any other experiments yielding negative +results in but one generation or even in a large +number of sequent generations.</p> + +<p>For instance, the latter consideration applies to the +negative results of Mr. Francis Galton's celebrated +<i>Experiments in Pangenesis</i>.<a name="FNanchor_82_82" id="FNanchor_82_82"></a><a href="#Footnote_82_82" class="fnanchor">[82]</a>. These consisted in +transfusing the blood of one variety of rabbit into +the veins of both sexes of another, and then allowing +the latter to breed together: in no case was there any +appearance in the progeny of characters distinctive +of the variety from which the transfused blood was +derived. But, as Mr. Galton himself subsequently +allowed, this negative result constitutes no disproof +of pangenesis, seeing that only a portion of the +parents' blood was replaced; that this portion, even +if charged with "gemmules," would contain but +a very small number of these hypothetical bodies, +compared with those contained in all the tissues of +the parents; and that even this small proportional +number would presumably be soon overwhelmed by +those contained in blood newly-made by the parents. +Nevertheless the experiment was unquestionably +worth trying, on the chance of its yielding a positive +result; for, in this event, the question at issue +would have been closed. Accordingly I repeated +these experiments (with the kind help of Professor +Schäfer), but with slight differences in the method, +designed to give pangenesis a better chance, so to +speak.</p> + +<p>Thus I chose wild rabbits to supply the blood, +and Himalayan to receive it—the former being the +ancestral type (and therefore giving reversion an<span class="pagenum"><a name="Page_146" id="Page_146">[Pg 146]</a></span> +opportunity of coming into play), while the latter, +although a product of domestication, is a remarkably +constant variety, and one which differs very much +in size and colour from the parent species. Again, +instead of a single transfusion, there were several +transfusions performed at different times. Moreover, +we did not merely allow the blood of one rabbit +to flow into the veins of the other (whereby little +more than half the blood could be substituted); +but sacrificed three wild rabbits for refilling the +vascular system of each tame one on each occasion. +Even as thus improved, however, the experiment +yielded only negative results, which, therefore, we +never published.</p> + +<p>Subsequently I found that all this labour, both +on Mr. Galton's part and our own, was simply +thrown away—not because it yielded only negative +results, but because it did not serve as a crucial +experiment at all. The material chosen was unserviceable +for the purpose, inasmuch as rabbits, +even when crossed in the ordinary way, never throw +intermediate characters. Needless to say, had I been +aware of this fact before, I should never have repeated +Mr. Galton's experiments—nor, indeed, would +he have originally performed them had he been aware +of it. So all this work goes for nothing. The research +must begin all over again with some other animals, +the varieties of which when crossed do throw intermediate +characters.</p> + +<p>Therefore I have this year made arrangements +for again repeating the experiments in question—only, +instead of rabbits, using well-marked varieties +of dogs. A renewed attack of illness, however, has<span class="pagenum"><a name="Page_147" id="Page_147">[Pg 147]</a></span> +necessitated the surrender of this research to other +hands, with a consequent delay in its commencement.</p> + +<p>My ignorance of the unfortunate peculiarity displayed +by rabbits in not throwing intermediate +characters has led to a further waste of time in +another line of experiment. On finding that mammalian +ovaries did not admit of being grafted, it +seemed to me that the next best thing to try would be +the transplantation of fertilized ova from one variety +to another, for the purpose of ascertaining whether, +if a parturition should take place under such circumstances, +gestation by the uterine mother would affect +the characters of the ovum derived from the ovarian +mother—she, of course, having been fertilized by a +male of her own variety. Of course it was necessary +that both the mothers should be in season at about the +same time, and therefore I again chose rabbits, seeing +that in the breeding season they are virtually in a +chronic state of "heat." I selected Himalayans and +Belgian hares, because they are well-marked varieties, +breed true, and in respect of colour are very different +from one another. It so happened that while I was +at work upon this experiment, it was also being tried, +unknown to me, by Messrs. Heape and Buckley who, +curiously enough, employed exactly the same material. +They were the first to obtain a successful result. +Two fertilized ova of the Angora breed having been +introduced into the fallopian tube of a Belgian hare, +developed there in due course, and gave rise to two +Angora rabbits in no way modified by their Belgian +hare gestation<a name="FNanchor_83_83" id="FNanchor_83_83"></a><a href="#Footnote_83_83" class="fnanchor">[83]</a>.</p> + +<p><span class="pagenum"><a name="Page_148" id="Page_148">[Pg 148]</a></span> +But, interesting and suggestive as this experiment +is in other connexions, it is clearly without significance +in the present one, for the reason already +stated. It will have to be tried on well-marked varieties +of other species of animals, which are known to throw +intermediate characters. Even, however, if it should +then yield a similarly negative result, the fact would +not tell against the inheritance of acquired characters; +seeing that an ovum by the time it is ripe is a finished +product, and therefore not to be expected, on any +theory of heredity, to be influenced as to its hereditary +potentialities by the mere process of gestation. On +the other hand, if it should prove that it does admit +of being thus affected, so that against all reasonable +expectation the young animal presents any of the +hereditary characters of its uterine mother, the +fact would terminate the question of the transmission +of acquired characters—and this quite as effectually +as would a similarly positive result in the case of +progeny from an ingrafted ovary of a different +variety. In point of fact, the only difference between +the two cases would be, that in the former it <i>might</i> +prove possible to close the question on the side of +Lamarckianism, in the latter it would <i>certainly</i> +close the question, either on this side or on the +opposite as the event would determine.</p> + +<p>The only additional fact that has hitherto been +published by the school of Weismann is the result +of Weismann's own experiment in cutting off the +tails of mice through successive generations. But +this experiment does not bear upon any question +that is in debate; for no one who is acquainted +with the literature of the subject would have expected<span class="pagenum"><a name="Page_149" id="Page_149">[Pg 149]</a></span> +any positive result to follow from such a line of +inquiry. As shown further back in the text, Darwin +had carefully considered the case of mutilations, +and explained that their non-transmissibility constitutes +no valid objection to his theory of pangenesis. +Furthermore, it may now be added, he expressly +alluded in this connexion to the cutting off of tails, +as practised by horse-breeders and dog-fanciers, +"through a number of generations, without any +inherited effect." He also alluded to the still better +evidence which is furnished by the practice of circumcision. +Therefore it is difficult to understand +the object of Weismann's experiment. Yet, other +than the result of this experiment, no new fact +bearing on the question at issue has been even so +much as alleged.</p> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_150" id="Page_150">[Pg 150]</a></p> + + + + +<h2>CHAPTER VI.<br /> +<span class="smcap">Characters as Hereditary and Acquired</span><br /> +(<i>conclusion</i><a name="FNanchor_84_84" id="FNanchor_84_84"></a><a href="#Footnote_84_84" class="fnanchor">[84]</a>).</h2> + +<p>In the foregoing chapters I have endeavoured +to be, before all things, impartial; and if it seems +that I have been arguing chiefly in favour of the +Lamarckian principles, this has been because the +only way of examining the question is to consider +what has to be said on the affirmative side, and +then to see what the negative side can say in +reply. Before we are entitled to discard the Lamarckian +factors <i>in toto</i>, we must be able to destroy +all evidence of their action. This, indeed, is what +the ultra-Darwinians profess to have done. But +is not their profession premature? Is it not evident +that they have not sufficiently considered certain +general facts of nature, or certain particular results +of experiment, which at all events appear inexplicable +by the theory of natural selection alone? +In any case the present discussion has been devoted +mainly to indicating such general facts and particular +results. If I have fallen into errors, either<span class="pagenum"><a name="Page_151" id="Page_151">[Pg 151]</a></span> +of statement or of reasoning, it is for the ultra-Darwinians +to correct them; but it may be well to +remark beforehand, that any criticism of a merely +general kind touching the comparative paucity of the +facts thus adduced in favour of Lamarckian doctrine, +will not stand as a valid criticism. For, as we +have seen in the opening part of the discussion, +even if use-inheritance and direct action of the +environment have been of high importance as factors +of organic evolution, it must be in almost all cases +impossible to dissociate their influence from that +of natural selection—at any rate where plants and +animals in a state of nature are concerned. On +the other hand, experiments expressly devised to +test the question have not hitherto been carried +out. Besides, the facts and arguments here adduced +are but <i>comparatively</i> few. For, unless it can be +shown that what has been said of reflex action, +instinct, so-called "self-adaptation" in plants, &c., is +wrong in principle, the facts which tell in favour +of Lamarckian theory are <i>absolutely</i> very numerous. +Only when considered in relation to cases where +we are unable to exclude the conceivable possibility +of natural selection having been at work, can +it be said that the facts in question are not +numerous.</p> + +<p>Comparatively few, then, though the facts may +be of which I have given some examples, in my +opinion they are amply sufficient for the purpose +in hand. This purpose is to show that the question +which we are now considering is very far from +being a closed question; and, therefore, that the +school of Weismann is much too precipitate in<span class="pagenum"><a name="Page_152" id="Page_152">[Pg 152]</a></span> +alleging that there is neither any necessity for, +nor evidence of, the so-called Lamarckian factors<a name="FNanchor_85_85" id="FNanchor_85_85"></a><a href="#Footnote_85_85" class="fnanchor">[85]</a>. +And this opinion, whatever it may be worth, is +at all events both deliberate and impartial. As +one of the first to doubt the transmission of acquired +characters, and as one who has spent many years +in experimental inquiries upon the subject, any +bias that I may have is assuredly against the +Lamarckian principles—seeing that nearly all my +experiments have yielded negative results. It was +Darwin himself who checked this bias. But if the +ultra-Darwinians of the last ten years had succeeded +in showing that Darwin was mistaken, I should be +extremely glad to fall into line with them. As +already shown, however, they have in no way affected +this question as it was left by Galton in 1875. And +if it be supposed a matter of but little importance +whether we agree with Galton in largely diminishing +the comparative potency of the Lamarckian +principles, or whether we agree with Weismann +in abolishing them together, it cannot be too often +repeated that such is an entirely erroneous view. +No matter how faintly or how fitfully acquired +characters may be transmitted, in so far as they +are likewise adaptive characters, their transmission +(and therefore their development) must be cumulative. +Hence, the only effect of attenuating our +estimate of their <i>intensity</i>, is that of increasing +our estimate of their <i>duration</i>—i.e. of the time over +which they have to operate in order to produce<span class="pagenum"><a name="Page_153" id="Page_153">[Pg 153]</a></span> +important results. And, even so, it is to be remembered +that the importance of such results is +not to be estimated by the magnitude of modification. +Far more is it to be estimated by the character +of modification as adaptive. For if functionally +produced changes, and changes produced in adaptive +response to the environment, are ever transmitted +in a cumulative manner, a time must sooner or +later arrive when they will reach a selective value +in the struggle for existence—when, of course, they +will be rapidly augmented by natural selection. +Thus, if in any degree operative at all, the great +function of these principles must be that of supplying +to natural selection those incipient stages of adaptive +modifications in all cases where, but for their +agency, there would have been nothing of the kind +to select. Themselves in no way dependent on +adaptive modifications having already attained a +selective value, these Lamarckian principles are +(under the Darwinian theory) direct causes of determinate +variation in adaptive lines; and variation +in those lines being cumulative, the result is that +natural selection is in large part presented with the +raw material of its manufacture—special material of +the particular kinds required, as distinguished from +promiscuous material of all kinds. And the more +complex the manufacture the more important will +be the work of this subordinate factory. We can +well imagine how the shell of a nut, for instance, +or even the protective colouring of an insect, may +have been gradually built up by natural selection +alone. But just in proportion as structures or organs +are not merely thus of passive <i>use</i> (where, of course,<span class="pagenum"><a name="Page_154" id="Page_154">[Pg 154]</a></span> +the Lamarckian principles cannot obtain), but require +to be actively <i>used</i>, in that proportion does it become +difficult to understand the <i>incipient</i> construction +of them by natural selection alone. Therefore, in +many such cases, if the incipient construction is +not to be explained by the Lamarckian principles, +it is difficult to see how it is to be explained at all.</p> + +<p>Furthermore, since the question as to the transmission +of acquired characters stands now exactly +as it did after the publication of Mr. Galton's +<i>Theory of Heredity</i> twenty years ago, it would seem +that our judgement with regard to it should remain +exactly what it was then. Although we must +"out-Darwin Darwin" to the extent of holding +that he assigned too large a measure of intensity +to the Lamarckian factors, no sufficient reason +has been shown for denying the existence of +these factors <i>in toto</i>; while, on the other hand, +there are certain general considerations, and certain +particular facts, which appear to render it probable +that they have played a highly important +part in the process of organic evolution as a whole. +At the same time, and in the present state of +our information, this judgement must be deemed +provisional, or liable eventually to be overturned +by experimental proof of the non-inheritance of +acquired characters. But, even if this should ever +be finally accomplished, the question would still +remain whether the principle of natural selection +alone is capable of explaining all the facts of adaptation; +and, for my own part, I should then be +disposed to believe that there must be some other, +though hitherto undiscovered, principle at work,<span class="pagenum"><a name="Page_155" id="Page_155">[Pg 155]</a></span> +which co-operates with natural selection, by playing +the subordinate role which was assigned by Darwin +to the principles of Lamarck.</p> + +<p>Finally, let it be noted that no part of the foregoing +argument is to be regarded as directed against +the <i>principle</i> of what Professor Weismann calls "continuity." +On the contrary, it appears to be self-evident +that this principle must be accepted in some degree +or another by every one, whether Darwinians, Neo-Darwinians, +Lamarckians, Neo-Lamarckians, or even +the advocates of special creation. Yet, to hear or +to read some of the followers of Weismann, one +can only conclude that, prior to his publications on +the subject, they had never thought about it at all. +These naturalists appear to suppose that until then +the belief of Darwinians was, that there could be +no hereditary "continuity" between any one organic +type and another (such, for instance, as between +Ape and Man), but that the whole structure of any +given generation must be due to "gemmules" +or "somato-plasm," derived exclusively from the +preceding generation. Nothing can show more +ignorance, or more thoughtlessness, with regard to +the whole subject. The very basis of the general +theory of evolution is that there must always have +been a continuity in the material substance of +heredity since the time when the process of evolution +began; and it was not reserved for our generation, +or even for our century, to perceive the special +nature of this material substance in the case of sexual +organisms. No, the real and the sole question, where +Weismann's theory of heredity is concerned, is simply +this—Are we to hold that this material substance<span class="pagenum"><a name="Page_156" id="Page_156">[Pg 156]</a></span> +has been <i>absolutely</i> continuous "since the first origin +of sexual propagation," always occupying a separate +"sphere" of its own, at all events to the extent of +never having been modified by the body substance +in which it resides (Lamarckian factors); <i>or</i>, are +we to hold that this "germ-plasm," "stirp," or "formative-material," +has been but <i>relatively</i> continuous, +so as to admit of some amount of commerce +with body-substance, and therefore to admit of +acquired characters, when sufficiently long continued +as such, eventually becoming congenital? If this +question be answered in the latter sense, of course +the further question arises as to the <i>degree</i> of +such commerce, or the <i>time</i> during which acquired +characters must continue to be acquired in successive +generations before they can sufficiently +impress themselves on the substance of heredity +to become congenital. But this is a subordinate +question, and one which, in the present state of +our information, it seems to me almost useless to +speculate upon. My own opinion has always been +the same as that of Mr. Galton; and my belief is +that eventually both Weismann and his followers +will gravitate into it. It was in order to precipitate +this result as far as possible that I wrote the +<i>Examination</i>. If it ever should be accomplished, +Professor Weismann's elaborate theory of evolution +will have had its bases removed.</p> + +<hr class="full" /> +<p class="pagenum"><a name="Page_157" id="Page_157">[Pg 157]</a></p> + + + + +<h2>SECTION II<br /> +<i>UTILITY</i></h2> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_159" id="Page_159">[Pg 159]</a></p> + + + + +<h2>CHAPTER VII.<br /> +<span class="smcap">Characters as Adaptive and Specific.</span></h2> + + +<p>One of the great changes which has been wrought +in biological science by the Darwinian theory of +natural selection, consists in its having furnished +an intelligible explanation of the phenomena of +<i>adaptation</i>. Indeed, in my opinion, this is the most +important function which this theory has had to +perform; and although we still find systematic +zoologists and systematic botanists who hold that +the chief merit of Darwin's work consists in its +having furnished an explanation of the origin of +<i>species</i>, a very little consideration is enough to +show that such an idea is but a survival, or a +vestige, of an archaic system of thought. So long +as species were regarded as due to separate acts +of creation, any theory which could explain their +production by a process of natural evolution became +of such commanding importance in this respect, +that we cannot wonder if in those days the principal +function of Darwin's work was held to be what +the title of that work—<i>The Origin of Species by +means of Natural Selection</i>—itself serves to convey. +And, indeed, in those days this actually was the +principal function of Darwin's work, seeing that in<span class="pagenum"><a name="Page_160" id="Page_160">[Pg 160]</a></span> +those days the <i>fact</i> of evolution itself, as distinguished +from its <i>method</i>, had to be proved; and +that the whole proof had to stand or fall with +the evidence which could be adduced touching the +mutability of species. Therefore, without question, +Darwin was right in placing this issue as to the +stability or instability of species in the forefront of +his generalizations, and hence in constituting it the +title of his epoch-making book. But nowadays, when +the fact of evolution has been sufficiently established, +one would suppose it self-evident that the theory +of natural selection should be recognized as covering +a very much larger field than that of explaining +the origin of <i>species</i>—that it should be recognized +as embracing the whole area of organic nature in +respect of <i>adaptations</i>, whether these happen to be +distinctive of species only, or of genera, families, +orders, classes, and sub-kingdoms. For it follows +from the general fact of evolution that species are +merely arbitrary divisions, which present no deeper +significance from a philosophical point of view than +is presented by well-marked varieties, out of which +they are in all cases believed to have arisen, and +from which it is often a matter of mere individual +taste whether they shall be separated by receiving +the baptism of a specific name. Yet, although +naturalists are now unanimously agreed that what +they classify as species are nothing more than +pronounced—and in some greater or less degree +permanent—varieties, so forcible is the influence of +traditional modes of thought, that many zoologists +and botanists still continue to regard the origin of +species as a matter of more importance than the origin<span class="pagenum"><a name="Page_161" id="Page_161">[Pg 161]</a></span> +of adaptations. Consequently, they continue to represent +the theory of natural selection as concerned, +primarily, with explaining the origin of species, +and denounce as a "heretic" any one who regards +the theory as primarily a theory of the origin and +cumulative development of adaptations—whether +structural or instinctive, and whether the adaptations +are severally characteristic of species only or of +any of the higher taxonomic divisions. Indeed, these +naturalists appear to deem it in some way a disparagement +of the theory to state that it is, primarily, +a theory of adaptations, and only becomes secondarily +a theory of species in those comparatively +insignificant cases where the adaptations happen +to be distinctive of the lowest order of taxonomic +division—a view of the matter which may fitly +be compared to that of an astronomer who should +define the nebular hypothesis as a theory of the +origin of Saturn's rings. It is indeed a theory of the +origin of Saturn's rings; but only because it is a theory +of the origin of the entire solar system, of which +Saturn's rings form a part. Similarly, the theory +of natural selection is a theory of the entire system +of organic nature in respect of adaptations, whether +these happen to be distinctive of particular species +only, or are common to any number of species.</p> + +<p>Now the outcry which has been raised over this +definition of the theory of natural selection is +a curious proof of the opposition which may be +furnished by habitual modes of thought to an exceedingly +plain matter of definition. For, I submit, that +no one can deny any of the following propositions; +nor can it be denied that from these propositions<span class="pagenum"><a name="Page_162" id="Page_162">[Pg 162]</a></span> +the foregoing definition of the theory in question +follows by way of necessity. The propositions are, +first, that natural selection is taken to be the +agency which is mainly, if not exclusively, concerned +in the evolution of adaptive characters: +secondly, that these characters, when evolved, are in +some cases peculiar to single species only, while in +other cases, and in process of time, they become +the common property of many species: thirdly, that +in cases where they are peculiar to single species +only, they constitute at all events one of the reasons +(or even, as the ultra-Darwinians believe, the only +reason) why the particular species presenting them +have come to be species at all. Now, these being +the propositions on which we are all agreed, it +obviously follows, of logical necessity, that the theory +in question is primarily one which explains the existence +of adaptive characters wherever these occur; +and, therefore, whether they happen to be restricted +to single species, or are common to a whole +group of species. Of course in cases where they +are restricted to single species, the theory which +explains the origin of these particular adaptations +becomes also a theory which explains the origin +of these particular species; seeing that, as we are +all agreed, it is in virtue of such particular adaptations +that such particular species exist. Yet even +in these cases the theory is, primarily, a theory +of the adaptations in virtue of which the particular +species exists; for, <i>ex hypothesi</i>, it is the adaptations +which condition the species, not the species the +adaptations. But, as just observed, adaptations may +be the common property of whole groups of species;<span class="pagenum"><a name="Page_163" id="Page_163">[Pg 163]</a></span> +and thus the theory of natural selection becomes +a theory of the origin of genera, of families, of orders, +and of classes, quite as much as it is a theory of the +origin of species. In other words, it is everywhere +a theory of adaptations; and it is only where +the adaptations happen to be restricted to single +species that the theory therefore and incidentally +becomes also a theory of the particular species which +presents them. Hence it is by no means the same +proposition to affirm that the theory of natural +selection is a theory of the origin of species, and +that it is a theory of the origin of adaptations, as +some of my critics have represented it to be; for +these two things are by no means conterminous. +And in as far as the two propositions differ, it is +perfectly obvious that the latter is the true one.</p> + +<p>Possibly, however, it may be said—Assuredly natural +selection is a theory of the origin (i.e. cumulative +development) of adaptations; and, no less assuredly, +although species owe their origin to such adaptations, +there is now no common measure between these two +things, seeing that in numberless cases the same +adaptations are the common property of numberless +species. But, allowing all this, we must still remember +that in their <i>first beginnings</i> all these adaptations must +have been distinctive of, or peculiar to, some one particular +species, which afterwards gave rise to a whole +genus, family, order, or class of species, all of which +inherited the particular adaptations derived from +this common ancestor, while progressively gaining +additional adaptive characters severally distinctive of +their subsequently diverging lines of descent. So +that really all adaptive characters must originally<span class="pagenum"><a name="Page_164" id="Page_164">[Pg 164]</a></span> +have been specific characters; and therefore there is +no real distinction to draw between natural selection +as a theory of species and as a theory of adaptations.</p> + +<p>Well, if this objection were to be advanced, the +answer would be obvious. Although it is true that +every adaptive character which is now common to +a group of species must originally have been distinctive +of a single parent species, it by no means +follows that in its first beginning as a specific character +it appeared in the fully developed form which it now +presents as a generic, family, ordinal, or yet higher +character. On the contrary, it is perfectly certain +that in the great majority of instances such cannot +possibly have been the case; and the larger the group +of species over which any particular adaptive character +now extends, the more evidently do we perceive that +this character must itself have been the product of +a gradual evolution by natural selection through an +innumerable succession of species in branching lines. +The wing of a bird, for example, is an adaptive +structure which cannot possibly have ever appeared +suddenly as a merely specific character: it must have +been slowly elaborated through an incalculable number +of successive species, as these branched into genera, +families, and orders of the existing class. So it is +with other class distinctions of an adaptive kind; +and so, in progressively lessening degrees, is it with +adaptive characters of an ordinal, a family, or a generic +value. That is to say, in <i>all</i> cases where an adaptive +structure is common to any considerable group of +species, we meet with clear evidence that the structure +has been the product of evolution through the ancestry +of those species; and this evidence becomes increasingly<span class="pagenum"><a name="Page_165" id="Page_165">[Pg 165]</a></span> +cogent the higher the taxonomic value +of the structure. Indeed, it may be laid down as +a general rule, that the greater the <i>degree</i> of adaptation +the greater is its <i>diffusion</i>—both as regards +the number of species which present it now, and +the number of extinct species through which it has +been handed down, in an ever ramifying extension +and in an ever improving form. Species, therefore, +may be likened to leaves: successive and transient +crops are necessary for the gradual building up of +adaptations, which, like the woody and permanent +branches, grow continuously in importance and +efficiency through all the tree of life. Now, in my +view, it is the great office of natural selection to see +to the growth of these permanent branches; and +although natural selection has likewise had an enormously +large share in the origination of each successive +crop of leaves—nay, let it be granted to the +ultra-Darwinians for the sake of argument, an exclusive +prerogative in this respect—still, in my view, +this is really the least important part of its work. +Not as an explanation of those merely permanent +varieties which we call species, but as an explanation +of the adaptive machinery of organic nature, which +has led to the construction both of the animal and +vegetable kingdoms in all their divisions do I regard +the Darwinian theory as one of the greatest generalizations +in the history of science.</p> + +<hr class="tb" /> + +<p>I have dwelt thus at some length upon a mere +matter of definition because, as we shall now find, +although it is but a matter of definition, it is fraught +with consequences of no small importance to the<span class="pagenum"><a name="Page_166" id="Page_166">[Pg 166]</a></span> +general theory of descent. Starting from an erroneous +definition of the theory of natural selection as primarily +a theory of the origin of species, both friends and +foes of the theory have concluded that the principle +of utility must by hypothesis be of universal occurrence +so far as species are concerned; whereas, if once +these naturalists were to perceive that their definition +of the theory is erroneous, they would likewise +perceive that their conclusion cannot follow deductively +from the theory itself. If such a conclusion is +to be established at all, it can only be by other +and independent evidence of the inductive kind—to +wit, by actual observation.</p> + +<p>Hence we see the importance of starting with an +accurate definition of the theory before proceeding +to examine the doctrine of utility as of universal +application to species—a doctrine which, as just +stated, has been habitually and expressly deduced +from the theory. This doctrine occurs in two forms; +or, more correctly, there are with reference to this +subject two distinct doctrines, which partly coincide +and partly exclude one another. First, it is held by +some naturalists that all species must necessarily owe +their origin to natural selection. And secondly, it is +held by other naturalists, that not only all species, +but likewise all specific characters must necessarily +do the same. Let us consider these two doctrines +separately.</p> + +<p>The first, and less extensive doctrine, rests on the +deduction that every species must owe its differentiation +as a species to the evolution of at least one adaptive +character, which is peculiar to that species. Although, +when thus originated, a species may come to present<span class="pagenum"><a name="Page_167" id="Page_167">[Pg 167]</a></span> +any number of other peculiar characters of a non-adaptive +kind, these merely indifferent peculiarities +are supposed to hang, as it were, on the peg supplied +by the one adaptive peculiarity; it is the latter which +conditions the species, and so furnishes an opportunity +for any number of the former to supervene. +But without the evolution of at least one adaptive +character there could have been no distinct species, +and therefore no merely adventitious characters as +belonging to that species. I will call this the +Huxleyan doctrine, because Professor Huxley is its +most express and most authoritative supporter.</p> + +<p>The second and more extensive doctrine I will call, +for the same reason, the Wallacean doctrine. This +is, as already stated, that it follows deductively from +the theory of natural selection, that not only all +species, but even all the distinctive characters of every +species, must necessarily be due to natural selection; +and, therefore, can never be other than themselves +useful, or, at the least, correlated with some other +distinctive characters which are so.</p> + +<p>Here, however, I should like to remark parenthetically, +that in choosing Professor Huxley and +Mr. Wallace as severally representative of the doctrines +in question, I earnestly desire to avoid any appearance +of discourtesy towards such high authorities.</p> + +<p>I am persuaded—as I shall hereafter seek to show +Darwin was persuaded—that the doctrine of utility as +universal where species are concerned, is, in both the +above forms, unsound. But it is less detrimental +in its Huxleyan than in its Wallacean form, because +it does not carry the erroneous deduction to +so extreme a point. Therefore let us first consider<span class="pagenum"><a name="Page_168" id="Page_168">[Pg 168]</a></span> +the doctrine in its more restricted form, and then proceed, +at considerably greater length, to deal with it in +its more extended form.</p> + +<hr class="tb" /> + +<p>The doctrine that all <i>species</i> must necessarily be due +to natural selection, and therefore must severally +present at least one adaptive character, appears to me +doubly erroneous.</p> + +<p>In the first place, it is drawn from what I have +just shown to be a false premiss; and, in the second +place, the conclusion does not follow even from this +premiss. That the premiss—or definition of the theory +as primarily a theory of the origin of species—is false, +I need not wait again to argue. That the conclusion +does not follow even from this erroneous premiss, +a very few words will suffice to prove. For, even if +it were true that natural selection is primarily a theory +of the origin of species, it would not follow that it +must therefore be a theory of the origin of <i>all</i> species. +This would only follow if it were first shown that the +theory is not merely <i>a</i> theory of the origin of species, +but <i>the</i> theory of the origin of species—i.e. that there +can be no further theory upon this subject, or any +cause other than natural selection which is capable of +transforming any single specific type.</p> + +<p>Needless to say, this cannot be shown by way of +deduction from the theory of natural selection itself—which, +nevertheless, is the only way whereby it is +alleged that the doctrine is arrived at<a name="FNanchor_86_86" id="FNanchor_86_86"></a><a href="#Footnote_86_86" class="fnanchor">[86]</a>.</p> + +<hr class="tb" /> + +<p>From the doctrine of utility as advocated by Professor<span class="pagenum"><a name="Page_169" id="Page_169">[Pg 169]</a></span> +Huxley, we may now pass on to consider it in +the much more comprehensive form advocated by +Mr. Wallace. Of course it is obvious that if the +doctrine is erroneous in its Huxleyan form, much +more must it be so in its Wallacean; and, therefore, +that having shown its erroneousness in its less extended +application, there is little need to consider it further in +its more extended form. Looking, however, to its +importance in this more extended application, I think +we ought to examine it independently as thus presented +by Mr. Wallace and his school. Let us therefore +consider, on its own merits, the following statement:—It +follows directly from the theory of natural +selection that not only all species, but likewise all +specific characters, must be due to natural selection, +and, therefore, must all be of use to the species +which present them, or else correlated with other +characters which are so.</p> + +<p>It seems worth while to observe, <i>in limine</i>, that +this doctrine is contradicted by that of Professor +Huxley. For supposing natural selection to be the +only principle concerned in the origin of all species, +it by no means follows that it is the sole agency +concerned in the origin of all specific characters. +It is enough for the former proposition if only +some of the characters distinctive of any given +species—nay, as he very properly expresses it, if +only one such character—has been due to natural +selection; for it is clear that, as he adds, "any number +of indifferent [specific] characters" may thus have +been furnished with an opportunity, so to speak, of +being produced by causes other than natural selection. +Hence, as previously remarked, the Huxleyan doctrine,<span class="pagenum"><a name="Page_170" id="Page_170">[Pg 170]</a></span> +although coinciding with the Wallacean up to the +point of maintaining utility as the only principle +which can be concerned in the origin of species, +designedly excludes the Wallacean doctrine where +this proceeds to extend any similar deduction to the +case of specific characters<a name="FNanchor_87_87" id="FNanchor_87_87"></a><a href="#Footnote_87_87" class="fnanchor">[87]</a>.</p> + +<p>In the next place, and with special reference to the +Wallacean doctrine, it is of importance to observe +that, up to a certain point there is complete agreement +between Darwinists of all schools. We all accept +natural selection as a true cause of the origin of species +(though we may not all subscribe to the Huxleyan +deduction that it is necessarily a cause of the origin of +<i>all</i> species). Moreover, we agree that specific characters +are often what is called rudimentary or vestigial; and, +once more, that our inability to detect the use of +any given structure or instinct is no proof that such +a structure or instinct is actually useless, seeing that +it may very probably possess some function hitherto +undetected, or possibly undetectable. Lastly, we all +agree that a structure which is of use may incidentally +entail the existence of some other structure which is +not of use; for, in virtue of the so-called principle of +correlation, the useless structure may be an indirect +consequence of natural selection, since its development +may be due to that of the useful structure, with the +growth of which the useless one is correlated.</p> + +<p>Nevertheless, while fully conceding all these facts +and principles to the Wallacean party, those who +think with Professor Huxley—and still more, of course, +those few naturalists who think as I do——are unable<span class="pagenum"><a name="Page_171" id="Page_171">[Pg 171]</a></span> +to perceive that they constitute any grounds for +holding the doctrine that all specific <i>characters</i> are, +or formerly have been, directly or indirectly due to +natural selection. My own reasons for dissenting +from this Wallacean doctrine are as follows.</p> + +<hr class="tb" /> + +<p>From what has just been said, it will be apparent +that the question in debate is not merely a question +of fact which can be settled by a direct appeal to +observation. If this were the case, systematic naturalists +could soon settle the question by their detailed +knowledge of the structures which are severally +distinctive of any given group of species. But so far +is this from being the case, that systematic naturalists +are really no better qualified to adjudicate upon the +matter than are naturalists who have not devoted so +much of their time to purely diagnostic work. The +question is one of general principles, and as such +cannot be settled by appeals to special cases. For +example, suppose that the rest of this chapter +were devoted to a mere enumeration of cases where +it appears impossible to suggest the utility of certain +specific characters, although such cases could be +adduced by the thousand, how should I be met at the +end of it all? Not by any one attempting to suggest +the utility, past or present, of the characters named; +but by being told that they must all present some +<i>hidden</i> use, must be <i>vestigial</i>, or else must be due to +<i>correlation</i>. By appealing to one or other of these assumptions, +our opponents are always able to escape the +necessity of justifying their doctrine in the presence of +otherwise inexplicable facts. No matter how many +seemingly "indifferent characters" we may thus accumulate,<span class="pagenum"><a name="Page_172" id="Page_172">[Pg 172]</a></span> +Mr. Wallace and his followers will always throw +upon us the impossible burden of proving the negative, +that these apparently useless characters do <i>not</i> present +some hidden or former use, are <i>not</i> due to correlation, +and therefore have <i>not</i> been produced by natural selection. +It is in vain to retort that the burden of proof +really lies the other way, or on the side of those who +affirm that there is utility where no man can see +it, or that there is correlation where no one can +detect it. Thus, so far as any appeal to particular +facts is concerned, it does not appear that there is any +<i>modus vivendi</i>. Our opinions upon the question are +really determined by the views which we severally +take on matters of general principle. The issue, +though it has a biological bearing, is a logical issue, +not a biological one: it turns exclusively on those +questions of definition and deduction with which +we have just been dealing.</p> + +<p>But although it thus follows that we cannot +determine in fact what proportion of apparently +useless characters are or are not really useful, we +may very easily determine in fact what proportion +of specific characters <i>fail to present any observable +evidences of utility</i>. Yet, even upon this question of +observable fact, it is surprising to note the divergent +statements which have of late years been +made by competent writers; statements in fact so +divergent that they can only be explained by some +want of sufficient thought on the part of those +naturalists who are antecedently persuaded that all +specific characters must be either directly or indirectly +due to natural selection. Hence they fail +to give to apparently useless specific characters the<span class="pagenum"><a name="Page_173" id="Page_173">[Pg 173]</a></span> +attention which, apart from any such antecedent +persuasion, they deserve. For example, a few years +ago I incidentally stated in a paper before the +Linnaean Society, that "a large proportional number +of specific characters" are of a trivial and apparently +unmeaning kind, to which no function admits of being +assigned, and also stated that Darwin himself had +expressly given utterance to the same opinion. +When these statements were made, I did not anticipate +that they would be challenged by anybody, +except perhaps, by Mr. Wallace. And, in order now +to show that my innocence at that time was not +due to ignorance of contemporary thought on such +matters, a sentence may here be quoted from a +paper which was read at the meeting of the +British Association of the same year, by a highly +competent systematic naturalist, Mr. Henry Seebohm, +and soon afterwards extensively republished. Criticizing +adversely my then recently published paper, +he said:—</p> + +<blockquote><p>"I fully admit the truth of this statement; and I presume +that few naturalists would be prepared to deny that 'distinctions +of specific value frequently have reference to structures which +are without any utilitarian significance<a name="FNanchor_88_88" id="FNanchor_88_88"></a><a href="#Footnote_88_88" class="fnanchor">[88]</a>.'"</p></blockquote> + +<p>But since that time the course of Darwinian speculation +has been greatly influenced by the writings of +Weismann, who, among other respects in which he +out-darwins Darwin, maintains the doctrine of utility +as universal. In consequence of the influence which +these writings have exercised, I have been more +recently and extensively accused of "heresy" to +Darwinian principles, for having stated that "a large<span class="pagenum"><a name="Page_174" id="Page_174">[Pg 174]</a></span> +proportional number of specific characters" do not +admit of being proved useful, or correlated with other +characters that are useful. Now, observe, we have +here a simple question of fact. We are not at present +concerned with the question how far the argument +from ignorance may be held to apply in mitigation +of such cases; but we are concerned only with the +question of fact, as to what proportional number of +cases actually occur where we are <i>unable to suggest</i> +the use of specific characters, or the useful characters +with which these apparently useless ones are correlated. +I maintain, as a matter of fact, that the cases +in question embrace "a large proportional number +of specific characters." On the other hand, I am +accused of betraying ignorance of species, and of the +work of "species-makers," in advancing this statement; +and have been told by Mr. Wallace, and +others of his school, that there is absolutely no +evidence to be derived from nature in support of my +views. Well, in the first place, if this be the case, +it is somewhat remarkable that a large body of +competent naturalists, such as Bronn, Broca, Nägeli, +Kerner, Sachs, De Vries, Focke, Henslow, Haeckel, +Kölliker, Eimer, Giard, Pascoe, Mivart, Seebohm, +Lloyd Morgan, Dixon, Beddard, Geddes Gulick, and +also, as we shall presently see, Darwin himself, should +have fallen into the same error. And it is further +remarkable that the more a man devotes himself to +systematic work in any particular department—whether +as an ornithologist, a conchologist, an entomologist, +and so forth—the less is he disposed to +accept the dogma of specific characters as universally +adaptive characters. But, in the second place, and<span class="pagenum"><a name="Page_175" id="Page_175">[Pg 175]</a></span> +quitting considerations of mere authority, I appeal +to the facts of nature themselves; and will now +proceed, as briefly as possible, to indicate the result +of such an appeal.</p> + +<p>For the following reasons, that birds and mammals +seem to furnish the best field for testing the +question by direct observation. First, these classes +present many genera which have been more carefully +worked out than is usually the case with +genera of invertebrates, or even of cold-blooded +vertebrates. Secondly, they comprise many genera +each including a large number of species, whose +habits and conditions of life are better known than +is the case with species belonging to large genera +of other classes. Thirdly, as birds and mammals +represent the highest products of evolution in respect +of organization, a more severe test is imposed than +could be imposed elsewhere, when the question is +as to the utility of specific characters; for if these +highest products of organization fail to reveal, in a +large proportional number of cases, the utility of their +specific characters, much more is this likely to be the +case among organic beings which stand lower in the +scale of organization, and therefore, <i>ex hypothesi</i>, +are less elaborate products of natural selection. +Fourthly, and lastly, birds and mammals are the +classes which Mr. Wallace has expressly chosen to +constitute his ground of argument with regard to +the issue on which we are now engaged.</p> + +<p>It would take far too long to show, even in epitome, +the results of this inquiry. Therefore I will +only state the general upshot. Choosing genera of +birds and mammals which contain a large number<span class="pagenum"><a name="Page_176" id="Page_176">[Pg 176]</a></span> +of species whose diagnostic characters have been +worked out with most completeness, I restricted +the inquiry to specific distinctions of colour, not +only for the sake of having a uniform basis for +comparisons, but still more because it seemed that +the argument from our ignorance of possibly unknown +uses could be more successfully met in the +case of slight differences of colour or of shading, +than in that of any differences of structure or of +form. Finally, after tabulating all the differences of +colour which are given as diagnostic of each species +in a genus, and placing in one column those which +may conceivably be useful, while placing in another +column those of which it appeared inconceivable +that any use could be suggested, I added up the +figures in the two columns, and thus obtained a +grand total of all the specific characters of the +genus in respect of colours, separated into the two +classes of conceivably useful and apparently useless. +Now, in all cases the apparently useless characters +largely preponderated over the conceivably useful +ones; and therefore I abundantly satisfied myself +regarding the accuracy of my previous statement, +that a large proportional number—if not an actual +majority—of specific characters belong to the latter +category.</p> + +<p>The following is a brief abstract of these results.</p> + +<p>With respect to Birds, a large number of cases +were collected wherein the characters of allied +species differ from one another in such minute +respects of colour or shading, that it seemed unreasonable +to suppose them due to any selective +value to the birds in question. It is needless—even<span class="pagenum"><a name="Page_177" id="Page_177">[Pg 177]</a></span> +if it were practicable on the present occasion—to +adduce this evidence in detail, since an +exceedingly good sample of it may be found in +a small book which is specially devoted to considering +the question in its relation to birds. I allude +to an essay by Mr. Charles Dixon, entitled <i>Evolution +without Natural Selection</i> (1885). In this work +Mr. Dixon embodies the results of five years' "careful +working at the geographical distribution and +variations of plumage of Palaearctic birds and their +allies in various other parts of the world"; and +shows, by a large accumulation of facts, not only +that there is no utility to be suggested in reference +to the minute or trivial differences of colouration +which he describes; but also that these differences +are usually correlated with isolation on the one +hand, or with slight differences of climate on the +other. Now it will be shown later on that both +these agents can be proved, by independent evidence, +capable of inducing changes of specific type without +reference to utility: therefore the correlation +which Mr. Dixon unquestionably establishes between +apparently useless (because utterly trivial) specific +distinctions on the one hand, and isolation or +climatic change on the other, constitutes additional +evidence to show that the uselessness is not only +apparent, but real. Moreover I have collected a +number of cases where such minute differences of +colour between allied species of birds happen to +affect parts of the plumage which are <i>concealed</i>—as +for instance, the breast and abdomen of creepers. In +such cases it seems impossible to suggest how natural +selection can have operated, seeing that the parts<span class="pagenum"><a name="Page_178" id="Page_178">[Pg 178]</a></span> +affected are not exposed to the view either of enemies +or of prey.</p> + +<p>Analogous illustrations to any amount may be drawn +from Mammals. For instance, I have worked through +the Marsupials with the aid of Mr. Oldfield Thomas' +diagnostic description of their numerous species. +Now, let us take any one of the genera, such as +the kangaroos. This comprises 23 species living on +an island continent of high antiquity, and not exposed +to the depredations of any existing carnivorous +enemies; so that there is here no present need +to vary colour for purposes of protection. Moreover, +in all cases the diagnostic distinctions of +colour are so exceedingly trivial, that even if large +carnivora were recently abundant in Australia, no one +could reasonably suggest that the differences in +question would then have been protective. On an +average, each of the 23 species presents rather more +than 20 peculiarities of shading, which are quoted +as specifically diagnostic. Altogether there are 474 +of these peculiarities distributed pretty evenly among +the 23 species; and in no case can I conceive that +utility can be suggested.</p> + +<hr class="tb" /> + +<p>Hitherto we have been considering the question of +fact, as to whether "a large proportional number +of specific characters" do or do not admit of having +their utility demonstrated, or even so much as plausibly +suggested. In the result, I can only conclude +that this question of fact is really not an open one, +seeing that it admits of an abundantly conclusive +answer by any naturalist who will take the trouble +to work through the species of any considerable<span class="pagenum"><a name="Page_179" id="Page_179">[Pg 179]</a></span> +number of genera in the way above indicated. But +although the question of fact is thus really closed, +there remains a more ultimate question as to its +theoretical interpretation. For, as already pointed +out, no matter how great an accumulation of such +facts may be collected, our opponents are always able +to brush them aside by their <i>a priori</i> appeal to the +argument from ignorance. In effect they say—We +do not care for any number of thousands of such +facts; it makes no difference to us what "proportional +number" of specific characters fail to show evidence +of utility; you are merely beating the air by adducing +them, for we are already persuaded, on antecedent +grounds, that <i>all</i> specific characters <i>must</i> be either +themselves useful, or correlated with others that are, +whether or not we can perceive the utility, or suggest +the correlation.</p> + +<p>To this question of theoretical interpretation, therefore, +we must next address ourselves. And here, +first of all, I should like to point out how sturdy must +be the antecedent conviction of our opponents, if +they are to maintain it in the face of such facts as +have just been adduced. It must be remembered +that this antecedent conviction is of a most uncompromising +kind. By its own premisses it is committed +to the doctrine that <i>all</i> specific characters, without +a single exception, <i>must</i> be either useful, vestigial, or +correlated. Well, if such be the case, is it not somewhat +astonishing that out of 474 differences of colour +which are distinctive of the 23 species of the genus +Macropus, no single one appears capable of having any +utility demonstrated, or indeed so much as suggested? +For even the recent theory that slight differences of<span class="pagenum"><a name="Page_180" id="Page_180">[Pg 180]</a></span> +colour, which cannot be conceived as serving any +other purpose, may enable the sexes of the same +species quickly to recognize each other, is not here +available. The species of the genus Macropus are +more conspicuously distinguished by differences of size +and form than by these minute differences of colour; +and therefore no such use can be attributed to the +latter. And, as previously stated, even within the +order Marsupialia the genus Macropus is not at all +exceptional in this respect; so that by including +other genera of the order it would be easy to gather +such apparently indifferent specific characters by +the hundred, without any one of them presenting +evidence—or even suggestion—of utility. How robust +therefore is the faith of an <i>a priori</i> conviction which +can stand against such facts as these! What, then, +are the <i>a priori</i> grounds on which it stands? +Mr. Wallace, the great leader of this school of thought, +says:—</p> + +<blockquote><p>"It is a necessary deduction from the theory of natural selection, +that none of the definite facts of organic nature, no special +organ, no characteristic form or marking, no peculiarities of +instinct or of habit, no relations between species or between +groups of species, can exist, but which must now be, or once +have been, <i>useful</i> to the individuals or the races which possess +them<a name="FNanchor_89_89" id="FNanchor_89_89"></a><a href="#Footnote_89_89" class="fnanchor">[89]</a>."</p></blockquote> + +<p>Here, then, we have in brief compass the whole +essence of our opponents' argument. It is confessedly +an argument <i>a priori</i>, a deduction from the theory +of natural selection, a supposed consequence of that +theory which is alleged to be so necessary that to<span class="pagenum"><a name="Page_181" id="Page_181">[Pg 181]</a></span> +dispute the consequence is tantamount to denying the +theory from which it is derived. In short, as before +stated, it is a question of theory, not a question of +fact: our difference of opinion is logical, not biological: +it depends on our interpretation of principles, not +on our observation of species. It will therefore be +my endeavour to show that the reasoning in question +is fallacious: that it is <i>not</i> a necessary deduction +from the theory of natural selection that no characteristic +form or marking, no peculiarities of instinct or +of habit, can exist, but which must now be, or once +have been, useful, or correlated with some other +peculiarity that is useful.</p> + +<p>"The tuft of hair on the breast of a wild turkey-cock +<i>cannot be of any use</i>, and it is doubtful whether +it can be ornamental in the eyes of the female bird;—indeed, +had the tuft appeared under domestication, +it would have been called a monstrosity<a name="FNanchor_90_90" id="FNanchor_90_90"></a><a href="#Footnote_90_90" class="fnanchor">[90]</a>."</p> + +<p>As a matter of common sense, unprejudiced by +dogma, this appears to be a perfectly sound judgement; +but if Wallace had asked Darwin to prove such +a negative, Darwin could only have replied that it +was for Wallace to prove the affirmative—and thus +the issue would have been thrown back upon a discussion +of general principles. Then Wallace would +have said—"The assertion of inutility in the case of +any organ or peculiarity which is not a rudiment or +a correlation <i>is not, and can never be</i>, the statement +of a fact, but <i>merely an expression of our ignorance of +its purpose or origin</i><a name="FNanchor_91_91" id="FNanchor_91_91"></a><a href="#Footnote_91_91" class="fnanchor">[91]</a>." Darwin, however, would have +replied:—"Our ignorance of the laws of variation is<span class="pagenum"><a name="Page_182" id="Page_182">[Pg 182]</a></span> +profound"; and while, on this account, we ought "to +be extremely cautious in <i>pretending to decide what +structures are now, or have formerly been, of use to +each species</i>," in point of fact "there can be little +doubt that the tendency to vary in the same manner +has <i>often</i> been so strong, that <i>all</i> individuals of the +same <i>species</i> have been similarly modified <i>without the +aid of any form of selection</i><a name="FNanchor_92_92" id="FNanchor_92_92"></a><a href="#Footnote_92_92" class="fnanchor">[92]</a>."</p> + +<p>It will be my endeavour in the following discussion +to show that Darwin would have had an immeasurable +advantage in this imaginary debate.</p> + +<p>To begin with, Wallace's deductive argument is +a clear case of circular reasoning. We set out by inferring +that natural selection is a cause from numberless +cases of observed utility as an effect: yet, when "in +a large proportional number" of cases we fail to +perceive any imaginable utility, it is argued that +nevertheless utility must be there, since otherwise +natural selection could not have been the cause.</p> + +<p>Be it observed, in any given case we may properly +anticipate utility as <i>probable</i>, even where it is not +perceived; because there are already so enormous +a number of cases where it is perceived, that, if the +principle of natural selection be accepted at all, we must +conclude with Darwin that it is "the <i>main</i> means of +modification." Therefore, in particular cases of unperceived +utility we may take this antecedent probability +as a guide in our biological researches—as has<span class="pagenum"><a name="Page_183" id="Page_183">[Pg 183]</a></span> +been done with such brilliant success both by Darwin +and Wallace, as well as by many of their followers. +But this is a very different thing from laying down +the universal maxim, that in <i>all</i> cases utility <i>must</i> +be present, whether or not we shall ever be able to +detect it<a name="FNanchor_93_93" id="FNanchor_93_93"></a><a href="#Footnote_93_93" class="fnanchor">[93]</a>. For this universal maxim amounts to an +assumption that natural selection has been the "<i>exclusive</i> +means of modification." That it has been "the +main means of modification" is proved by the generality +of the observed facts of adaptation. That it has +been "the exclusive means of modification," with the +result that these facts are universal, cannot be thus +proved by observation. Why, then, is it alleged? +Confessedly it is alleged by way of deduction from +the theory of natural selection itself. Or, as above +stated, after having deduced the theory from the facts, +it is sought to deduce the facts from the theory.</p> + +<p>Thus far I have been endeavouring to show +that the universality of adaptation cannot be inferred +from its generality, or from the theory of natural selection +itself. But, of course, the case would be quite +different if there were any independent evidence—or +rather, let us say, any logical argument—to show that +natural selection is "the exclusive means of modification." +For in this event it would no longer involve +circular reasoning to maintain that all specific characters +are likewise adaptive characters. It might +indeed appear antecedently improbable that no +other principle than natural selection can possibly +have been concerned in the differentiation of those +relatively permanent varieties which we call species—that +in all the realm of organic nature, and in all the<span class="pagenum"><a name="Page_184" id="Page_184">[Pg 184]</a></span> +complexities of living processes, there is no room for +any other influence in the production of change, even +of the most trivial and apparently unmeaning kind. +But if there were any good evidence or logical argument +to the contrary, this antecedent presumption +would have to give way; and the certainty that all +specific characters are likewise adaptive characters +would be determined by the cogency of such evidence +or argument as could be adduced. In short, we are +not entitled to conclude—and still less does it follow +"as a necessary deduction from the theory of natural +selection"—that all the details of specific differentiation +must in every case be either useful, vestigial, or +correlated, <i>unless it has been previously shown, by +independent evidence, or accurate reasoning, that there +is no room for any other principle of specific change</i>.</p> + +<p>This, apparently, is the central core of the question. +Therefore I will now proceed to consider such arguments +as have been adduced to prove that, other +than natural selection, there <i>can</i> have been no "means +of modification." And, after having exhibited the +worthlessness of these arguments, I will devote the +next chapter to showing that, as a matter of observable +fact, there <i>are</i> a considerable number of +other principles, which can be proved to be capable +of producing such minute differences of form and +colour as "in a large proportional number" of cases +constitute diagnostic distinctions between species and +species.</p> + +<p>First, then, for the reasons <i>a priori</i>—and they +are confessedly <i>a priori</i>—which have been adduced +to prove that natural selection has been what in +Darwin's opinion it has not been,—"the <i>exclusive</i><span class="pagenum"><a name="Page_185" id="Page_185">[Pg 185]</a></span> +means of modification." Disregarding the Lamarckian +factors—which, even if valid, have but little relation to +the present question, seeing that they are concerned, +almost exclusively, with the evolution of <i>adaptive</i> +characters—it is alleged that natural selection must +occupy the whole field, because no other principle +of change can be allowed to operate in the presence +of natural selection. Now, I fully agree that this +statement may hold as regards any principle of change +which is deleterious; but clearly it does not hold +as regards any principle which is merely neutral. +If any one were to allege that specific characters +are frequently detrimental to the species presenting +them, he would no doubt lay himself open to the +retort that natural selection could not allow such +characters to persist; or, which amounts to the same +thing, that it <i>does</i> "necessarily follow from the theory +of natural selection" that specific characters can +never be in any large number, or in any large +measure, <i>harmful</i> to the species presenting them. +But where the statement is that specific characters +are frequently <i>indifferent</i>—again to use Professor +Huxley's term—the retort loses all its relevancy. No +reason has ever been shown why natural selection should +interfere with merely indifferent characters, supposing +such to have been produced by any of the agencies +which we shall presently have to consider. Therefore +this argument—or rather assertion—goes for nothing.</p> + +<p>The only other argument I have met with on this +side of the question is one that has recently been +adduced by Mr. Wallace. He says:—</p> + +<blockquote><p>"One very weighty objection to the theory that <i>specific</i> +characters can ever be wholly useless appears to have been<span class="pagenum"><a name="Page_186" id="Page_186">[Pg 186]</a></span> +overlooked by those who have maintained the frequency of +such characters, and that is, their almost necessary instability<a name="FNanchor_94_94" id="FNanchor_94_94"></a><a href="#Footnote_94_94" class="fnanchor">[94]</a>."</p></blockquote> + +<p>This argument he proceeds to elaborate at considerable +length, but fails to perceive what appears +to me the obvious answer. Provided that the cause +of the useless character is constant, there is no +difficulty in understanding why the character is +stable. Utility is not the only principle that can +lead to stability: any other principle must do the +same, provided that it acts for a sufficient length +of time, and with a sufficient degree of uniformity, +on all the individuals of a species. This is a consideration +the cogency of which was clearly recognized +by Darwin, as the following quotations will +show. Speaking of unadaptive characters, he says +they may arise as merely</p> + +<blockquote><p>"fluctuating variations, which sooner or later become <i>constant</i> +through the nature of the organism and of surrounding conditions, +<i>but not through natural selection</i><a name="FNanchor_95_95" id="FNanchor_95_95"></a><a href="#Footnote_95_95" class="fnanchor">[95]</a>."</p></blockquote> + +<p>Elsewhere we read:—</p> + +<blockquote><p>"Each of the endless variations which we see in the plumage +of our fowls must have had some efficient cause; and if the +<i>same</i> cause were to act <i>uniformly</i> during a long series of generations +on <i>many</i> individuals, <i>all</i> probably would be modified in +the same manner."</p></blockquote> + +<p>As special illustrations of this fact I may quote +the following cases from Darwin's works.</p> + +<blockquote><p>"Dr. Bachman states that he has seen turkeys raised from +the eggs of wild species, lose their metallic tints, and become +spotted in the third generation. Mr. Yarrell many years ago +informed me that the wild ducks bred in St James' Park lost<span class="pagenum"><a name="Page_187" id="Page_187">[Pg 187]</a></span> +their true plumage after a few generations. An excellent +observer (Mr. Hewitt) ... found that he could not breed wild +ducks true for more than five or six generations, as they proved +so much less beautiful. The white collar round the neck of the +mallard became broader and more irregular, and white feathers +appeared in the duckling's wings &c.<a name="FNanchor_96_96" id="FNanchor_96_96"></a><a href="#Footnote_96_96" class="fnanchor">[96]</a>"</p></blockquote> + +<p>Now, such cases—to which numberless others might +be added—prove that even the subtle and inconspicuous +causes incidental to domestication are +capable of inducing changes of specific character +quite as great, and quite as "stable," as any that +in a state of nature are taken to constitute specific +distinctions. Yet there can here be no suggestion +of utility, inasmuch as the change takes place in the +course of a few generations, and therefore without +leaving time for natural selection to come into play—even +if it ever could come into play among the +sundry domesticated birds in question.</p> + +<p>But the facts of domestication also make for the +same conclusion in another way—namely, by proving +that when time enough <i>has</i> been allowed for the production +of useless changes of greater magnitude, +such changes are not infrequently produced. And +the value of this line of evidence is that, great as are +the changes, it is impossible that either natural or +artificial selection can have been concerned in their +production. It will be sufficient to give two examples—both +with regard to structure.</p> + +<p>The first I will render in the words whereby it +has already been stated in my own paper on +<i>Physiological Selection</i>, because I should like to take +this opportunity of answering Mr. Wallace's objection +to it.</p><p><span class="pagenum"><a name="Page_188" id="Page_188">[Pg 188]</a></span></p> + +<blockquote><p>"Elsewhere (<i>Origin of Species</i>, p. 158) Mr. Darwin points out +that modifications which appear to present obvious utility are +often found on further examination to be really useless. This +latter consideration, therefore, may be said to act as a foil to +the one against which I am arguing, namely, that modifications +which appear to be useless may nevertheless be useful. But +here is a still more suggestive consideration, also derived from +Mr. Darwin's writings. Among our domesticated productions +changes of structure—or even structures wholly new—not unfrequently +arise, which are in every way analogous to the apparently +useless distinctions between wild species. Take, for example, +the following most instructive case:—</p> + +<div class="figcenter" style="width: 376px;"> +<img src="images/illus_200.jpg" width="376" height="256" alt="Old Irish Pig, showing jaw-appendages" title="Old Irish Pig, showing jaw-appendages" /> +<span class="caption"><span class="smcap">Fig. 2.</span>—Old Irish Pig, showing jaw-appendages (after Richardson).</span></div> + +<p>"'Another curious anomaly is offered by the appendages +described by M. Eudes-Deslongchamps as often characterizing +the Normandy pigs. These appendages are always attached +to the same spot, to the corners of the jaws; they are cylindrical, +about three inches in length, covered with bristles, and with +a pencil of bristles rising out of a sinus on one side; they have +a cartilaginous centre with two small longitudinal muscles; +they occur either symmetrically on both sides of the face, +or on one side alone. Richardson figures them on the gaunt +old Irish Greyhound pig; and Nathusius states that they<span class="pagenum"><a name="Page_189" id="Page_189">[Pg 189]</a></span> +occasionally appear in all the long-eared races, but are not +strictly inherited, for they occur or fail in the animals of the +same litter. As no wild pigs are known to have analogous +appendages, we have at present no reason to suppose that their +appearance is due to reversion; and if this be so, we are forced +to admit that a somewhat complex, though apparently useless, +structure may be suddenly developed without the aid of +selection<a name="FNanchor_97_97" id="FNanchor_97_97"></a><a href="#Footnote_97_97" class="fnanchor">[97]</a>.'"</p></blockquote> + +<p>To this case Mr. Wallace objects:—</p> + +<blockquote><p>"But it is expressly stated that they are not constant; they +appear 'frequently' or 'occasionally,' they are 'not strictly +inherited, for they occur or fail in animals of the same litter'; +and they are not always symmetrical, sometimes appearing on +one side of the face alone. Now, whatever may be the cause +or explanation of these anomalous appendages, they cannot be +classed with 'specific characters,' the most essential features +of which are, that they <i>are</i> symmetrical, that they <i>are</i> inherited, +and that they <i>are</i> constant<a name="FNanchor_98_98" id="FNanchor_98_98"></a><a href="#Footnote_98_98" class="fnanchor">[98]</a>."</p></blockquote> + +<p>But, to begin with, I have not classed these appendages +with "specific characters," nor maintained +that Normandy pigs ought to be regarded as specifically +distinct on account of them. What I said +was:—</p> + +<blockquote><p>"Now, if any such structure as this occurred in a wild species, +and if any one were to ask what is the use of it, those who rely +on the argument from ignorance would have a much stronger +case than they usually have; for they might point to the +cartilage supplied with muscles, and supporting a curious +arrangement of bristles, as much too specialized a structure to +be wholly meaningless. Yet we happen to know that this +particular structure is wholly meaningless<a name="FNanchor_99_99" id="FNanchor_99_99"></a><a href="#Footnote_99_99" class="fnanchor">[99]</a>."</p></blockquote> +<p><span class="pagenum"><a name="Page_190" id="Page_190">[Pg 190]</a></span></p> +<p>In the next place, is it either fair or reasonable to +expect that a varietal character of presumably very +recent origin should be as strongly inherited—and +therefore as constant both in occurrence and symmetry—as +a true specific character, say, of a thousand +times its age? Even characters of so-called "constant +varieties" in a state of nature are usually less constant +than specific characters; while, again, as Darwin +says, "it is notorious that specific characters are +more variable than generic,"—the reason in both +cases being, as he proceeds to show, that the less +constant characters are characters of more recent +origin, and therefore less firmly fixed by heredity<a name="FNanchor_100_100" id="FNanchor_100_100"></a><a href="#Footnote_100_100" class="fnanchor">[100]</a>. +Hence I do not understand how Mr. Wallace can +conclude, as he does, "that, admitting that this peculiar +appendage is wholly useless and meaningless, the fact +would be rather an argument against specific characters +being also meaningless, because the latter never +have the characteristics [i.e. inconstancy of occurrence, +form, and transmission] which this particular +variation possesses<a name="FNanchor_101_101" id="FNanchor_101_101"></a><a href="#Footnote_101_101" class="fnanchor">[101]</a>." Mr. Wallace can scarcely +suppose that when specific characters first arise, +they present the three-fold kind of constancy +to which he here alludes. But, if not, can it be +denied that these peculiar appendages appear to +be passing through a phase of development which +all "specific characters" must have passed through,<span class="pagenum"><a name="Page_191" id="Page_191">[Pg 191]</a></span> +before they have had time enough to be firmly +fixed by heredity<a name="FNanchor_102_102" id="FNanchor_102_102"></a><a href="#Footnote_102_102" class="fnanchor">[102]</a>?</p> + +<p>If, however, even this should be denied, what +will be said of the second case, that of the niata +cattle?</p> + +<blockquote><p>"I saw two herds on the northern bank of the Plata.... The +forehead is very short and broad, with the nasal end of the skull, +together with the whole plane of the upper molar-teeth, curved +upwards. The lower jaw projects beyond the upper, and has +a corresponding upward curvature.... The skull which I presented +to the College of Surgeons has been thus described +by Professor Owen. 'It is remarkable from the stunted development +of the nasals, premaxillaries, and fore part of the lower +jaw, which is unusually curved upwards to come into contact +with the premaxillaries. The nasal bones are about one-third +the ordinary length, but retain almost their normal breadth. +The triangular vacuity is left between them and the frontal +and lachrymal, which latter bone articulates with the premaxillary, +and thus excludes the maxillary from any junction<span class="pagenum"><a name="Page_192" id="Page_192">[Pg 192]</a><br /><a name="Page_193" id="Page_193">[Pg 193]</a></span> +with the nasal.' So that even the connexion of some of the +bones is changed. Other differences might be added: thus the +plane of the condyles is somewhat modified, and the terminal +edge of the premaxillaries forms an arch. In fact, on comparison +with the skull of a common ox, scarcely a single bone presents +the same exact shape, and the whole skull has a wonderfully +different appearance<a name="FNanchor_103_103" id="FNanchor_103_103"></a><a href="#Footnote_103_103" class="fnanchor">[103]</a>."</p></blockquote> + +<div class="figcenter" style="width: 337px;"> +<img src="images/illus_204.jpg" width="337" height="600" alt="Skulls of Niata Ox and Wild White Ox" title="Skulls of Niata Ox and Wild White Ox" /> +<span class="caption"><span class="smcap">Fig. 3.</span>—Drawn from nature. R. Coll. Surg. Mus.</span></div> + +<p>As I cannot find that this remarkable skull has +been figured before, I have had the accompanying +woodcut made in order to compare it with the +skull of a Charsley Forest ox; and a glance is sufficient +to show what "a wonderfully different appearance" +it presents.</p> + +<hr class="tb" /> + +<p>Now the important points in the present connexion +with regard to this peculiar race of cattle are the +following.</p> + +<p>Their origin is not known; but it must have been +subsequent to the year 1552, when cattle were first +introduced to America from Europe, and it is known +that such cattle have been in existence for at least +a century. The breed is very true, and a niata bull +and cow invariably produce niata calves. A niata +bull crossed with a common cow, and the reverse +cross, yield offspring having an intermediate character, +but with the niata peculiarities highly conspicuous<a name="FNanchor_104_104" id="FNanchor_104_104"></a><a href="#Footnote_104_104" class="fnanchor">[104]</a>.</p> + +<p>Here, then, we have unquestionable evidence of +a whole congeries of very distinctive characters, so +unlike anything that occurs in any other cattle, +that, had they been found in a state of nature, +they would have been regarded as a distinct<span class="pagenum"><a name="Page_194" id="Page_194">[Pg 194]</a></span> +species. And the highly peculiar characters which +they present conform to all "the most essential +features of specific characters," as these are stated +by Mr. Wallace in his objection to the case of the +pig's appendages. That is to say, "they <i>are</i> symmetrical, +they <i>are</i> inherited, and they <i>are</i> constant." +In point of fact, they are <i>always</i> "constant," both as +to occurrence and symmetry, while they are so +completely "inherited" that not only does "a niata +bull and cow <i>invariably</i> produce niata calves"; but +even when crossed with other cattle the result is a +<i>hybrid</i>, "with the niata character <i>strongly</i> displayed."</p> + +<p>Hence, if we were to follow Mr. Wallace's criteria +of specific characters, which show that the pig's +appendages "cannot be classed with specific characters" +(or with anything of the nature of specific +characters), it would follow that the niata peculiarities +<i>can</i> be so classed. This, therefore, is a case where +he will find all the reasons which in other cases +he takes to justify him in falling back upon the +argument from ignorance. The cattle are half +wild, he may urge; and so the three-fold constancy +of their peculiar characters may very well +be due, either directly or indirectly, to natural +selection—i.e. they may either be of some hidden +use themselves, or correlated with some other modifications +that are of use: it is, he may say, as in +such cases he often does say, for us to disprove both +these possibilities.</p> + +<p>Well, here we have one of those rare cases where +historical information, or other accidents, admit of +our discharging this burden of proving a negative. +Darwin's further description shows that this customary<span class="pagenum"><a name="Page_195" id="Page_195">[Pg 195]</a></span> +refuge in the argument from ignorance is most +effectually closed. For—</p> + +<blockquote><p>"When the pasture is tolerably long, these cattle feed as well +as common cattle with their tongue and palate; but during the +great droughts, when so many animals perish on the Pampas, +the niata breed lies under a great disadvantage, and would, +if not attended to, become extinct; for the common cattle, like +horses, are able to keep alive by browsing with their lips on the +twigs of trees and on reeds; this the niatas cannot so well do, +as their lips do not join, and hence they are found to perish +before the common cattle. This strikes me as a good illustration +of how little we are able to judge from the ordinary +habits of an animal, on what circumstances, occurring only at +long intervals of time, its rarity or extinction may depend. +It shows us, also, how natural selection would have determined +the rejection of the niata modification, had it arisen in a state +of nature<a name="FNanchor_105_105" id="FNanchor_105_105"></a><a href="#Footnote_105_105" class="fnanchor">[105]</a>."</p></blockquote> + +<p>Hence, it is plainly <i>impossible</i> to attribute this +modification to natural selection, either as acting +directly on the modified parts themselves, or indirectly +through correlation of growth. And as the +modification is of specific magnitude on the one +hand, while it presents all "the most essential features +of specific characters" on the other, I do not +see any means whereby Mr. Wallace can meet it +on his <i>a priori</i> principles. It would be useless to +answer that these characters, although conforming to +all his tests of specific characters, differ in respect +of being deleterious, and would therefore lead to extermination +were the animals in a wholly wild state; +because, considered as an argument, this would involve +the assumption that, apart from natural selection, +only deleterious characters can arise under nature—i. e.<span class="pagenum"><a name="Page_196" id="Page_196">[Pg 196]</a></span> +that merely "indifferent" characters can never +do so, which would be absurd. Indeed, I have chosen +this case of the niata cattle expressly because their +strongly marked peculiarities <i>are</i> deleterious, and +therefore exclude Mr. Wallace's appeal to the argument +from ignorance of a possible utility. But if even +these pronounced and deleterious peculiarities can +arise and be perpetuated with such constancy and +fidelity, much more is this likely to be the case with +less pronounced and merely neutral peculiarities.</p> + +<p>It may, however, be further objected that these +cattle are not improbably the result of <i>artificial</i> selection. +It may be suggested that the semi-monstrous +breed originated in a single congenital variation, or +"sport," which was isolated and multiplied as a +curiosity by the early settlers. But even if such be the +explanation of this particular case, the fact would +not weaken our illustration. On the contrary, it +would strengthen our general argument, by showing an +additional means whereby indifferent specific characters +can arise and become fixed in a state of nature. +As it seems to me extremely probable that the niata +cattle did originate in a congenital monstrosity, which +was then isolated and multiplied by human agency +(as is known to have been the case with the "ancon +sheep"), I will explain why this tends to strengthen +our general argument.</p> + +<p>It is certain that if these animals were ever subject +to artificial isolation for the purpose of establishing +their breed, the process must have ceased a long time +ago, seeing that there is no memory or tradition of +its occurrence. Now this proves that, however the +breed may have originated, it has been able to maintain<span class="pagenum"><a name="Page_197" id="Page_197">[Pg 197]</a></span> +its many and highly peculiar characters for a +number of generations without the help of selection, +either natural or artificial. This is the first point to +be clear upon. Be its origin what it may, we know +that this breed has proved capable of perpetuating +itself with uniform "constancy" for a number of +generations after the artificial selection has ceased—supposing +such a process ever to have occurred. And +this certain fact that artificial selection, even if it +was originally needed to establish the type, has not +been needed to perpetuate the type, is a full answer +to the supposed objection. For, in view of this fact, it +is immaterial what the origin of the niata breed may +have been. In the present connexion, the importance +of this breed consists in its proving the subsequent +"stability" of an almost monstrous form, continued +through a long series of generations by the force +of heredity alone, without the aid of any form of +selection.</p> + +<p>The next point is, that not only is a seeming +objection to the illustration thus removed, but that, +if we do entertain the question of origin, and if we +do suppose the origin of these cattle to have been +in a congenital "sport," afterwards multiplied by +artificial isolation, we actually strengthen our general +argument by increasing the importance of this particular +illustration. For the illustration then becomes +available to show how indifferent specific characters +may sometimes originate in merely individual sports, +which, if not immediately extinguished by free +intercrossing, will perpetuate themselves by the +unaided force of heredity. But this is a point to which +we shall recur in the ensuing chapter.</p><p><span class="pagenum"><a name="Page_198" id="Page_198">[Pg 198]</a></span></p> + +<p>In conclusion, it is worth while to remark, with +regard to Mr. Wallace's argument from constancy, +that, as a matter of fact, utility does not seem to +present any greater power in securing "stability of +characters" than any other cause of like constancy. +Thus, for instance, whatever the causes may have +been which have produced and perpetuated the niata +breed of cattle, they have certainly produced a wonderful +"stability" of a great modification in a wonderfully +short time. And the same has to be said of the +ducks in St. James' Park, as well as sundry other cases. +On the other hand, when, as in the case of numberless +natural species, modification has been undoubtedly +produced by natural selection, although the modification +must have had a very much longer time in which +to have been fixed by heredity, it is often far from +being stable—notwithstanding that Mr. Wallace +regards stability as a criterion of specific characters. +Indeed—and this is more suggestive still—there even +seems to be a kind of <i>inverse</i> proportion between the +utility and the stability of a specific character. The explanation +appears to be (<i>Origin of Species</i>, pp. 120-2), +that the more a specific character has been forced on +by natural selection on account of its utility, the less +time will it have had to become well fixed by heredity +before attaining a full development. Moreover, as +Darwin adds, in cases where the modification has +not only been thus "comparatively recent," but also +"extraordinarily great," the probability is that the +parts so modified must have been very variable in the +first instance, and so are all the more difficult to +render constant by heredity. Thus we see that utility +is no better—even if it be so good—a cause of<span class="pagenum"><a name="Page_199" id="Page_199">[Pg 199]</a></span> +stability in specific characters, as are the unknown +causes of stability in many varietal characters<a name="FNanchor_106_106" id="FNanchor_106_106"></a><a href="#Footnote_106_106" class="fnanchor">[106]</a>.</p> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_200" id="Page_200">[Pg 200]</a></p> + + + + +<h2>CHAPTER VIII.<br /> +<span class="smcap">Characters as Adaptive and Specific</span><br /> +(<i>continued</i>).</h2> + + +<p>Let us now proceed to indicate some of the +causes, other than natural selection, which may be +regarded as adequate to induce such changes in +organic types as are taken by systematists to constitute +diagnostic distinctions between species and +species. We will first consider causes external to +organisms, and will then go on to consider those which +occur within the organisms themselves: following, in +fact, the classification which Darwin has himself laid +down. For he constantly speaks of such causes as +arising on the one hand, from "changed conditions of +life" and, on the other hand, from "the nature of the +organism"—that is, from internal processes leading +to "variations which seem to us in our ignorance to +arise spontaneously."</p> + +<p>In neither case will it be practicable to give more +than a brief <i>résumé</i> of all that might be said on these +interesting topics.</p> + + +<h3>I. <i>Climate.</i></h3> + +<p>There is an overwhelming mass of evidence to +prove that the assemblage of external conditions of +life conveniently summarized in the word Climate,<span class="pagenum"><a name="Page_201" id="Page_201">[Pg 201]</a></span> +exercise a potent, an uniform, and a permanent influence +on specific characters.</p> + +<p>With regard to plants, Darwin adduces a number +of facts to show the effects of climate on wheat, +cabbages, and other vegetables. Here, for example, +is what he says with regard to maize imported +from America to Germany:—</p> + +<blockquote><p>"During the first year the plants were twelve feet high, and +a few seeds were perfected; the lower seeds in the ear kept +true to their proper form, but the upper seeds became slightly +changed. In the second generation the plants were from nine +to ten feet high, and ripened their seed better; the depression +on the outer side of the seed had almost disappeared, and the +original beautiful white colour had become duskier. Some +of the seeds had even become yellow, and in their now rounded +form they approached the common European maize. In the +third generation nearly all resemblance to the original and very +distinct American parent-form was lost<a name="FNanchor_107_107" id="FNanchor_107_107"></a><a href="#Footnote_107_107" class="fnanchor">[107]</a>."</p></blockquote> + +<p>As these "highly remarkable" changes were effected +in but three generations, it is obvious that they +cannot have been dependent on selection of any +kind. The same remark applies to trees. Thus,—</p> + +<blockquote><p>"Mr. Meehan has compared twenty-nine kinds of American +trees with their nearest European allies, all grown in close +proximity and under as nearly as possible the same conditions. +In the American species he finds, with the rarest exceptions, +that the leaves fall earlier in the season, and assume before their +fall a brighter tint; that they are less deeply toothed or serrated; +that the buds are smaller; that the trees are more diffuse in +growth and have fewer branchlets; and, lastly, that the seeds +are smaller—all in comparison with the corresponding European +species. Now, considering that these corresponding trees<span class="pagenum"><a name="Page_202" id="Page_202">[Pg 202]</a></span> +belong to several distinct orders, and that they are adapted to +widely different stations, it can hardly be supposed that their +differences are of any special service to them in the New and +Old worlds; and, if so, such differences cannot have been gained +through natural selection, and must be attributed to the long +continued action of a different climate<a name="FNanchor_108_108" id="FNanchor_108_108"></a><a href="#Footnote_108_108" class="fnanchor">[108]</a>."</p></blockquote> + +<p>These cases, however, I quote mainly in order to +show Darwin's opinion upon the matter, with reference +to the absence of natural selection. For, where the +vegetable kingdom is concerned, the fact of climatic +variation is so general, and in its relation to diagnostic +work so important, that it constitutes one of +the chief difficulties against which species-makers +have to contend. And the more carefully the subject +is examined the greater does the difficulty become. +But, as to this and other general facts, it will be +best to allow a recognized authority to speak; and +therefore I will give a few extracts from Kerner's +work on <i>Gute und schlechte Arten</i>.</p> + +<p>He begins by showing that geographical (or it +may be topographical) varieties of species are often +so divergent, that without a knowledge of intermediate +forms there could be no question as to their being +good species. As a result of his own researches on +the subject, he can scarcely find language strong +enough to express his estimate of the extent and +the generality of this source of error. In different +parts of Europe, or even in different parts of the +Alps, he has found these climatic varieties in such +multitudes and in such high degrees both of constancy +and divergence, that, after detailing his results,<span class="pagenum"><a name="Page_203" id="Page_203">[Pg 203]</a></span> +he finishes his essay with the following remarkable +conclusions:—</p> + +<blockquote><p>"Die Wissenchaft geht aber ihren Entwicklungsgang im +grossen Ganzen gerade so, wie die Erkenntniss bei jedem einzelnen +Naturforscher. Fast jeder Botaniker muss seinen Entwicklungsgang +durchmachen und gelangt endlich mehr oder weniger +nahe zu demselben Ziele. Die Ungleichheit besteht nur darin, +dass der eine langsamer, der andere aber rascher bei dem Ziele +ankommt. Anfänglich müht sich jeder ab, die Formen in +hergebrachter Weise zu gliedern und die 'guten Arten' herauszulesen. +Mit der Erweiterung des Gesichtskreises und mit der +Vermehrung der Anschauungen aber schwindet auch immer +mehr der Boden unter den Füssen, die bisher für unverrückbar +gehaltenen Grenzen der gut geglaubten Arten stellen sich als +eine der Natur angelegte Zwangsjacke heraus, die Uebcrzeugung, +dass die Grenzen, welche wir ziehen, eben nur künstliche sind, +gewinnt immer mehr und mehr die Oberhand, und wer nicht +gerade zu den hartgesottenen Eigensinnigen gehört, und wer +die Wahrheit höher stellt als das starre Festhalten an seinen +früheren Ansichten, geht schliesslich bewusst oder unbewusst +in das Lager derjenigen über, in welchem auch ich mir ein +bescheidenes Plätzchen aufgesucht habe."</p></blockquote> + +<p>By these "hard-boiled" botanists he means those +who entertain the traditional notion of a species as +an assemblage of definite characters, always and +everywhere associated together. This notion (Artsbeständigkeit) +must be entirely abandoned. Summarizing +Kerner's facts for their general results we find +that his extensive investigations have proved that in +his numberless kinds of European plants the following +relations frequently obtain. Supposing that there are +two or more allied species, A and B, then A' and B' +may be taken to represent their respective types as +found in some particular area. It does not signify<span class="pagenum"><a name="Page_204" id="Page_204">[Pg 204]</a></span> +whether A' and B' are geographically remote from, +or close to, A and B; the point is that, whether in +respect of temperature, altitude, moisture, character +of soil, &c., there is some difference in the conditions +of life experienced by the plants growing at the different +places. Now, in numberless plants it is found +that the typical or constant peculiarities of A' differ +more from those of A than they do from those of B; +while, conversely, the characters of A' may bear more +resemblance to those of B' than they do to those +of A—on account of such characters being due to +the same external causes in both cases. The consequence +is that A' might more correctly be classified +with B', or <i>vice versa</i>. Another consequence is that +whether A and B, or A' and B', be recorded as the +"good species" usually depends upon which has +happened to have been first described.</p> + +<p>Such a mere abstract of Kerner's general results, +however, can give no adequate idea of their cogency: +for this arises from the number of species in which +specific characters are thus found to change, and even to +<i>interchange</i>, with different conditions of life. Thus he +gives an amusing parable of an ardent young botanist, +Simplicius, who starts on a tour in the Tyrol with +the works of the most authoritative systematists to +assist him in his study of the flora. The result is +that Simplicius becomes so hopelessly bewildered in +his attempts at squaring their diagnostic descriptions +with the facts of nature, that he can only exclaim +in despair—"Sonderbare Flora, diese tirolische, in +welcher so viele characteristische Pflanzen nur +schlechte Arten, oder gar noch schlechter als schlechte +Arten, sind." Now, in giving illustrations of this<span class="pagenum"><a name="Page_205" id="Page_205">[Pg 205]</a></span> +young man's troubles, Kerner fills five or six pages +with little else than rows of specific names.</p> + +<p>Upon the whole, Kerner concludes that the more +the subject is studied, the more convinced must the +student become that all distinction between species as +"good" and "bad" vanishes. In other words, the more +that our knowledge of species and of their diagnostic +characters increases, the more do we find that "bad +species" multiply at the expense of "good species"; so +that eventually we must relinquish the idea of "good +species" altogether. Or, conversely stated, we must +agree to regard as equally "good species" any and +every assemblage of individuals which present the +same peculiarities: provided that these peculiarities +do not rise to a generic value, they equally deserve +to be regarded as "specific characters," no matter +how trivial, or how local, they may be. In fact, he +goes so far as to say that when, as a result of +experiments in transplantation from one set of +physical conditions to another, seedlings are found +to present any considerable and constant change in +their specific characters, these seedlings are no less +entitled to be regarded as a "good species" than +are the plants from which they have been derived. +Probably few systematists will consent to go quite +so far as this; but the fact that Kerner has been +led deliberately to propound such a statement as +a result of his wide observations and experiments +is about as good evidence as possible on the +points with which we are here concerned. For even +Simplicius would hardly be quite so simple as to +suppose that each one of all the characters which +he observes in his "remarkable flora," so largely<span class="pagenum"><a name="Page_206" id="Page_206">[Pg 206]</a></span> +composed of "bad or even worse than bad species," +is of utilitarian significance.</p> + +<p>Be it noted, however, that I am not now expressing +my own opinion. There are weighty reasons +against thus identifying climatic variations with +good species—reasons which will be dealt with +in the next chapter. Kerner does not seem to +appreciate the weight of these reasons, and therefore +I do not call him as a witness to the subject as +a whole; but only to that part of it which has to do +with the great and general importance of climatic +variability in relation to diagnostic work. And thus +far his testimony is fully corroborated by every other +botanist who has ever attended to the subject. +Therefore it does not seem worth while to quote +further authorities in substantiation of this point, such +as Gärtner, De Candolle, Nägeli, Peter, Jordan, &c. +For nowadays no one will dispute the high generality +and the frequently great extent of climatic variation +where the vegetable kingdom is concerned. Indeed, +it may fairly be doubted whether there is any one +species of plant, whose distribution exposes it to any +considerable differences in its external conditions of +life, which does not present more or less considerable +differences as to its characters in different parts of its +range. The principal causes of such climatic variation +appear to be the chemical, and, still more, the +mechanical nature of soil; temperature; intensity and +diurnal duration of light in spring and summer; +moisture; presence of certain salts in the air and soil +of marine plants, or of plants growing near mineral +springs; and sundry other circumstances of a more +or less unknown character.</p> + +<p><span class="pagenum"><a name="Page_207" id="Page_207">[Pg 207]</a></span> +Before closing these remarks on climatic variation in +the vegetable kingdom, prominent attention must be +directed to a fact of broad generality and, in relation +to our present subject, of considerable importance. +This is that the same external causes very frequently +produce the same effects in the way of specific change +throughout large numbers of <i>unrelated</i> species—i.e. +species belonging to different genera, families, and +orders. Moreover, throughout all these unrelated +species, we can frequently trace a uniform correlation +between the degrees of change and the degrees to +which they have been subjected to the causes in +question.</p> + +<p>As examples, all botanists who have attended to +the subject are struck by the similarity of variation +presented by different species growing on the same +soils, altitudes, latitudes, longitudes, and so forth. +Plants growing on chalky soils, when compared with +those growing on richer soils, are often more thickly +covered with down, which is usually of a white or +grey colour. Their leaves are frequently of a bluish-green +tint, more deeply cut, and less veined, while +their flowers tend to be larger and of a lighter +tint. There are similarly constant differences in +other respects in varieties growing on sundry other +kinds of soils. Sea-salt has the general effect, on +many different kinds of plants, of producing moist +fleshy leaves, and red tints. Experiments in transplantation +have shown that these changes may be +induced artificially; so there can be no doubt as to its +being this that and the other set of external conditions +which produces them in nature. Again, dampness +causes leaves to become smoother, greener, less cut,<span class="pagenum"><a name="Page_208" id="Page_208">[Pg 208]</a></span> +and the flowers to become darker; while dryness +tends to produce opposite effects. I need not go on +to specify the particular results on all kinds of plants +of altitude, latitude, longitude, and so forth. For we +are concerned only with the fact that these two +correlations may be regarded as general laws appertaining +to the vegetable kingdom—namely, (A) that +the same external causes produce similar varietal +effects in numerous unallied species of plants; and, +(B) that the more these species are exposed to such +causes the greater is the amount of varietal effect +produced—so that, for instance, on travelling from +latitude to latitude, longitude to longitude, altitude +to altitude, &c., we may see greater and greater +degrees of such definite and more or less common +varietal changes affecting the unallied species in +question. Now these general laws are of importance +for us, because they prove unequivocally that it is the +direct action of external conditions of life which +produce climatic variations of specific types. And, +taken in connexion with the results of experiments in +transplantation (which in a single generation may +yield variations similar to those found in nature under +similar circumstances), these general laws still further +indicate that climatic variations are "indifferent" +variations. In other words, we find that changes of +specific characters are of widespread occurrence in the +vegetable kingdom, that they are constantly and even +proportionally related to definite external circumstances, +but yet that, in as far as they are climatic, they cannot +be attributed to the agency of natural selection<a name="FNanchor_109_109" id="FNanchor_109_109"></a><a href="#Footnote_109_109" class="fnanchor">[109]</a>.</p> +<p><span class="pagenum"><a name="Page_209" id="Page_209">[Pg 209]</a></span></p> +<p>Turning next to animals, it may first be observed +that climatic conditions do not appear to exercise +an influence either so general or so considerable +as in the case of plants. Nevertheless, although +these influences are relatively more effective in the +vegetable kingdom than they are in the animal, +absolutely considered they are of high generality and +great importance even in the latter. But as this +fact is so well recognized by all zoologists, it will +be needless to give more than a very few illustrations. +Indeed, throughout this discussion on climatic influences +my aim is merely to give the general reader +some idea of their importance in regard to systematic +natural history; and, therefore, such particular +cases as are mentioned are selected only as samples +of whole groups of cases more or less similar.</p> + +<p>With regard to animals, then, we may best begin +by noticing that, just as in the case of plants, there is +good evidence of the same external causes producing +the same effects in multitudes of species belonging +to different genera, families, orders, and even classes. +Moreover, we are not without similarly good evidence +of <i>degrees</i> of specific change taking place in correlation +with <i>degrees</i> of climatic change, so that we may +frequently trace a gradual progress of the former as +we advance, say, from one part of a large continent +to another. Instances of these correlations are +not indeed so numerous in the animal kingdom as +they are in the vegetable. Nevertheless they are +amply sufficient for our present purposes.</p> + +<p>For example, Mr. Allen has studied in detail<span class="pagenum"><a name="Page_210" id="Page_210">[Pg 210]</a></span> +changes of size and colour among birds and mammals +on the American continent; and he finds a wonderfully +close sliding scale of both, corresponding +stage by stage with gradual changes of climate. +Very reasonably he attributes this to the direct +influence of climatic conditions, without reference +to natural selection—as does also Mr. Gould with +reference to similar facts which he has observed +among the birds of Australia. Against this view +Mr. Wallace urges, "that the effects are due to the +greater or less need of protection." But it is difficult +to believe that such can be the case where so innumerable +a multitude of widely different species +are concerned—presenting so many diverse habits, +as well as so many distinct habitats. Moreover, the +explanation seems incompatible with the <i>graduated</i> +nature of the change, and also with the fact that not +only colouration but size, is implicated.</p> + +<p>We meet with analogous facts in butterflies. +Thus <i>Lycaena agestis</i> not only presents seasonal +variations, (A) and (B); but while (A) and (B) are +respectively the winter and summer forms in +Germany, (B) and (C) are the corresponding forms +in Italy. Therefore, (B) is in Germany the summer +form, and in Italy the winter form—the German +winter form (A) being absent in Italy, while the +Italian summer form (C) is absent in Germany. +Probably these facts are due to differences of temperature +in the two countries, for experiments have +shown that when pupae of sundry species of moths +and butterflies are exposed to different degrees of +temperature, the most wonderful changes of colour +may result in the insects which emerge. The remarkable<span class="pagenum"><a name="Page_211" id="Page_211">[Pg 211]</a></span> +experiments of Dorfmeister and Weismann +in relation to this subject are well known. More +recently Mr. Merrifield has added to their facts, and +concludes that the action of cold upon the pupae—and +also, apparently, upon the larvae—has a tendency +to produce dark hues in the perfect insect<a name="FNanchor_110_110" id="FNanchor_110_110"></a><a href="#Footnote_110_110" class="fnanchor">[110]</a>.</p> + +<p>But, passing now from such facts of climatic variations +over wide areas to similar facts within small +areas, in an important <i>Memoir on the Cave Fauna +of North America</i>, published a few years ago by the +American Academy of Sciences, it is stated:—</p> + +<blockquote><p>"As regards change of colour, we do not recall an exception to +the general rule that all cave animals are either colourless or +nearly white, or, as in the case of Arachnida and Insects, much +paler than their out-of-door relatives."</p></blockquote> + +<p>Now, when we remember that these cave faunas +comprise representatives of nearly all classes of the +animal kingdom, it becomes difficult, if not impossible, +to imagine that so universal a discharge of +colouring can be due to natural selection. It must +be admitted that the only way in which natural +selection could act in this case would be indirectly +through the principle of correlation. There being no +light in the caves, it can be of no advantage to the +animals concerned that they should lose their colour +for the sake of protection, or for any other reason of +a similarly direct kind. Therefore, if the loss of colour +is to be ascribed to natural selection, this can only +be done by supposing that natural selection has here +acted indirectly through the principle of correlation. +There is evidence to show that elsewhere modification<span class="pagenum"><a name="Page_212" id="Page_212">[Pg 212]</a></span> +or loss of colour is in some cases brought about by +natural selection, on account of the original colour +being correlated with certain physiological characters +(such as liability to particular diseases, &c.); so that +when natural selection operates directly upon these +physiological characters, it thereby also operates +indirectly upon the correlated colours. But to suppose +that this can be the explanation of the uniform +diminution of colour in all inhabitants of dark caves +would be manifestly absurd. If there were only one +class of animals in these caves, such as Insects, it +might be possible to surmise that their change of +colour is due to natural selection acting directly upon +their physiological constitutions, and so indirectly +upon their colours. But it would be absurd to +suppose that such can be the explanation of the +facts, when these extend in so similar a manner over +so many scores of species belonging to such different +types of animal life.</p> + +<p>With more plausibility it might be held that the +universal discharge of colour in these cave-faunas +is due, not to the presence, but to the absence of +selection—i. e. to the cessation of selection, or panmixia. +But against this—at all events as a full or +general explanation—lie the following facts. First, +in the case of Proteus—which has often been kept +for the purposes of exhibition &c., in tanks—the skin +becomes dark when the animal is removed from the +cave and kept in the light. Secondly, deep-sea faunas, +though as much exposed as the cave-faunas, to the +condition of darkness, are not by any means invariably +colourless. On the contrary, they frequently present +brilliant colouration. Thus it is evident that if panmixia<span class="pagenum"><a name="Page_213" id="Page_213">[Pg 213]</a></span> +be suggested in explanation of the discharge +of colouring in cave-faunas, the continuance of colour +in deep-sea faunas appears to show the explanation +insufficient. Thirdly, according to my view of the +action of panmixia as previously explained, no <i>total</i> +discharge of colouration is likely to be caused by such +action alone. At most the bleaching as a result +of the mere withdrawal of selection would proceed +only to some comparatively small extent. Fourthly, +Mr. Packard in the elaborate <i>Memoir on Cave +Fauna</i>, already alluded to, states that in some of +the cases the phenomena of bleaching appear to have +been induced within very recent times—if not, indeed, +within the limits of a single generation. Should +the evidence in support of this opinion prove trustworthy, +of course in itself it disposes of any suggestion +either of the presence or the absence of natural +selection as concerned in the process.</p> + +<p>Nevertheless, I myself think it inevitable that to +some extent the cessation of selection must have +helped in discharging the colour of cave faunas; +although for the reasons now given it appears to me +that the main causes of change must have been of +that direct order which we understand by the term +climatic.</p> + +<p>As regards dogs, the Rev. E. Everest found it impossible +to breed Scotch setters in India true to their type. +Even in the second generation no single young dog +resembled its parents either in form or shape. "Their +nostrils were more contracted, their noses more pointed, +their size inferior, and their limbs more slender<a name="FNanchor_111_111" id="FNanchor_111_111"></a><a href="#Footnote_111_111" class="fnanchor">[111]</a>." +Similarly on the coast of New Guinea, Bosman says<span class="pagenum"><a name="Page_214" id="Page_214">[Pg 214]</a></span> +that imported breeds of dogs "alter strangely; their +ears grow long and stiff like those of foxes, to which +colour they also incline ... and in three or four +broods their barking turns into a howl<a name="FNanchor_112_112" id="FNanchor_112_112"></a><a href="#Footnote_112_112" class="fnanchor">[112]</a>."</p> + +<p>Darwin gives numerous facts showing the effects of +climate on horses, cattle, and sheep, in altering, more +or less considerably, the characters of their ancestral +stocks. He also gives the following remarkable case +with regard to the rabbit. Early in the fifteenth +century a common rabbit and her young ones were +turned out on the island of Porto Santo, near Madeira. +The feral progeny now differ in many respects from +their parent stock. They are only about one-third of +the weight, present many differences in the relative +sizes of different parts, and have greatly changed in +colour. In particular, the black on the upper surface +of the tail and tips of the ears, which is so constant +in all other wild rabbits of the world as to be given +in most works as a specific character, has entirely +disappeared. Again, "the throat and certain parts of +the under surface, instead of being pure white, are +generally grey or leaden colour," while the upper +surface of the whole body is redder than in the +common rabbit. Now, what answer have our opponents +to make to such a case as this? Presumably +they will answer that the case simply proves the +action of natural selection during the best part of 400 +years on an isolated section of a species. Although +we cannot say of what use all these changes have +been to the rabbits presenting them, nevertheless we +<i>must</i> believe that they have been produced by natural +selection, and therefore <i>must</i> present some hidden use<span class="pagenum"><a name="Page_215" id="Page_215">[Pg 215]</a></span> +to the isolated colony of rabbits thus peculiarly +situated. Four centuries is long enough to admit of +natural selection effecting all these changes in the case +of so rapidly breeding an animal as the rabbit, and therefore +it is needless to look further for any explanation +of the facts. Such, I say, is presumably the answer +that would be given by the upholders of natural +selection as the only possible cause of specific change. +But now, in this particular case it so happens that +the answer admits of being conclusively negatived, +by showing that the great assumption on which it +reposes is demonstrably false. For Darwin examined +two living specimens of these rabbits which had +recently been sent from Porto Santo to the Zoological +Gardens, and found them coloured as just +described. Four years afterwards the dead body +of one of them was sent to him, and then he found +that the following changes had taken place. "The ears +were plainly edged, and the upper surface of the tail +was covered with blackish-grey fur, and the whole +body was much less red; so that under the English +climate this individual rabbit has recovered the proper +colour of its fur in rather less than four years!"</p> + +<p>Mr. Darwin adds:—</p> + +<blockquote><p>"If the history of these Porto Santo rabbits had not been +known, most naturalists, on observing their much reduced size, +their colour, reddish above and grey beneath, their tails and +ears not tipped with black, would have ranked them as a +distinct species. They would have been strongly confirmed in +this view by seeing them alive in the Zoological Gardens, and +hearing that they refused to couple with other rabbits. Yet this +rabbit, which there can be little doubt would thus have been +ranked as a distinct species, as certainly originated since the +year 1420<a name="FNanchor_113_113" id="FNanchor_113_113"></a><a href="#Footnote_113_113" class="fnanchor">[113]</a>."</p></blockquote> +<p><span class="pagenum"><a name="Page_216" id="Page_216">[Pg 216]</a></span></p> +<p>Moreover, it certainly originated as a direct result +of climatic influences, independent of natural selection; +seeing that, as soon as individual members of this +apparently new species were restored to their original +climate, they recovered their original colouration.</p> + +<p>As previously remarked, it is, from the nature +of the case, an exceedingly difficult thing to prove +in any given instance that natural selection has not +been the cause of specific change, and so finally to +disprove the assumption that it must have been. +Here, however, on account of historical information, +we have a crucial test of the validity of this assumption, +just as we had in the case of the niata cattle; +and, just as in their case, the result is definitely +and conclusively to overturn the assumption. If +these changes in the Porto Santo rabbits had been +due to the gradual influence of natural selection +guided by inscrutable utility, it is simply impossible +that the same individual animals, in the course of +their own individual <span class="correction" title="Transcriber's Note: 'lifetimes' in the text.">life-times</span>, should revert to the +specific characters of their ancestral stock on being +returned to the conditions of their ancestral climate. +Therefore, unless any naturalist is prepared to contradict +Darwin's statement that the changes in +question amount to changes of specific magnitude, +he can find no escape from the conclusion that +distinctions of specific importance may be brought +about by changes of habitat alone, without reference +to utility, and therefore independently of natural +selection.</p> + +<p class="pagenum"><a name="Page_217" id="Page_217">[Pg 217]</a></p> + + +<h3>II. <i>Food.</i></h3> + +<p>Although, as yet, little is definitely known on the +subject, there can be no doubt that in the case of +many animals differences of food induce differences +of colour within the <span class="correction" title="Transcriber's Note: 'lifetime' in the text.">life-time</span> of individuals, and +therefore independently of natural selection.</p> + +<p>Thus, sundry definite varieties of the butterfly +<i>Euprepia caja</i> can be reared according to the different +nourishment which is supplied to the caterpillar; and +other butterflies are also known on whose colouring +and markings the food of the caterpillar has great +influence<a name="FNanchor_114_114" id="FNanchor_114_114"></a><a href="#Footnote_114_114" class="fnanchor">[114]</a>.</p> + +<p>Again, I may mention the remarkable case communicated +to Darwin by Moritz Wagner, of a species +of <i>Saturnia</i>, some pupae of which were transported +from Texas to Switzerland in 1870. The moths +which emerged in the following year were like the +normal type in Texas. Their young were supplied +with leaves of <i>Juglans regia</i>, instead of their natural +food, <i>J. nigra</i>; and the moths into which these +caterpillars changed were so different from their +parents, both in form and colour, "that they were +reckoned by entomologists as a distinct species<a name="FNanchor_115_115" id="FNanchor_115_115"></a><a href="#Footnote_115_115" class="fnanchor">[115]</a>."</p> + +<p>With regard to mollusks, M. Costa tells us that +English oysters, when turned down in the Mediterranean, +"<i>rapidly</i> became like the true Mediterranean<span class="pagenum"><a name="Page_218" id="Page_218">[Pg 218]</a></span> +oyster, altered their manner of growth, and formed +prominent diverging rays." This is most probably due +to some change of food. So likewise may be the even +more remarkable case of <i>Helix nemoralis</i>, which was +introduced from Europe to Virginia a few years ago. +Under the new conditions it varied to such an extent +that up to last year no less than 125 varieties had +been discovered. Of these 67, or more than half, +are new—that is, unknown in the native continent of +the species<a name="FNanchor_116_116" id="FNanchor_116_116"></a><a href="#Footnote_116_116" class="fnanchor">[116]</a>.</p> + +<p>In the case of Birds, the Brazilian parrot <i>Chrysotis +festiva</i> changes the green in its feathers to red or +yellow, if fed on the fat of certain fishes; and the +Indian Lori has its splendid colouring preserved by +a peculiar kind of food (Wallace). The Bullfinch +is well known to turn black when fed on hemp +seeds, and the Canary to become red when fed on +cayenne pepper (Darwin). Starting from these facts, +Dr. Sauermann has recently investigated the subject +experimentally; and finds that not only finches, but +likewise other birds, such as fowls, and pigeons, are +subject to similar variations of colour when fed on +cayenne pepper; but in all cases the effect is produced +only if the pepper is given to the young birds +before their first moult. Moreover, he finds that +a moist atmosphere facilitates the change of colour, +and that the ruddy hue is discharged under the +influence either of sunlight or of cold. Lastly, he +has observed that sundry other materials such as +glycerine and aniline dyes, produce the same results; +so there can be no doubt that organic compounds +probably occur in nature which are capable of<span class="pagenum"><a name="Page_219" id="Page_219">[Pg 219]</a></span> +directly affecting the colours of plumage when eaten +by birds. Therefore the presence of such materials +in the food-stuffs of birds occupying different areas +may very well in many cases determine differences +of colouration, which are constant or stable so long +as the conditions of their production are maintained.</p> + + +<h3>III. <i>Sexual Selection.</i></h3> + +<p>Passing on now to causes of specific change which +are internal, or comprised within the organisms +themselves, we may first consider the case of Sexual +Selection.</p> + +<p>Mr. Wallace rejects the theory of sexual selection +<i>in toto</i>, and therefore nothing that can be said under +this head would be held by him to be relevant. +Many naturalists, however, believe that Darwin was +right in the large generalization which he published +under this title; and in so far as any one holds that +sexual selection is a true cause of specific modification, +he is obliged to believe that innumerable specific +characters—especially in birds and mammals—have +been produced without reference to utility (other, +of course, than utility for sexual purposes), and +therefore without reference to natural selection. This +is so obvious that I need not pause to dilate upon it. +One remark, however, may be useful. Mr. Wallace +is able to make a much more effective use of his +argument from "necessary instability" when he +brings it against the Darwinian doctrine of sexual +selection, than he does when he brings it against the +equally Darwinian doctrine of specific characters in +general not being all necessarily due to natural<span class="pagenum"><a name="Page_220" id="Page_220">[Pg 220]</a></span> +selection. In the latter case, it will be remembered, +he is easily met by showing that the causes of specific +change other than natural selection, such as food, +climate, &c., may be quite as general, persistent, and +uniform, as natural selection itself; and therefore in +this connexion Mr. Wallace's argument falls to the +ground. But the argument is much more formidable +as he brings it to bear against the theory of sexual +selection. Here he asks, What is there to guarantee +the uniformity and the constancy of feminine taste +with regard to small matters of embellishment through +thousands of generations, and among animals living +on extensive areas? And, as we have seen in Part 1, +it is not easy to supply an answer. Therefore this +argument from the "necessary instability of character" +is of immeasurably greater force as thus applied +against Darwin's doctrine of sexual selection, than it +is when brought against his doctrine that all specific +characters need not necessarily be due to natural +selection. Therefore, also, if any one feels disposed +to attach the smallest degree of value to this argument +in the latter case, consistency will require him +to allow that in the former case it is simply overwhelming, +or in itself destructive of the whole theory +of sexual selection. And, conversely, if his belief in +the theory of sexual selection can survive collision +with this objection from instability, he ought not to +feel any tremor of contact when the objection is +brought to bear against his scepticism regarding the +alleged utility of all specific characters. For assuredly +no specific character which is apparent to our eyes +can be supposed to be so refined and complex (and +therefore so presumably inconstant and unstable), as<span class="pagenum"><a name="Page_221" id="Page_221">[Pg 221]</a></span> +are those minute changes of cerebral structure on +which a <span class="correction" title="Transcriber's Note: 'pyschological' in the text.">psychological</span> preference for all the refined +shadings and many pigments of a complicated +pattern must be held ultimately to depend. For this +reason, then, as well as for those previously adduced, +if any one agrees with Darwin in holding to the +theory of sexual selection notwithstanding this objection +from the necessary instability of unuseful +embellishments, <i>a fortiori</i> he ought to disregard the +objection altogether in its relation to useless specific +characters of other kinds.</p> + +<p>But quite apart from this consideration, which +Mr. Wallace and his followers may very properly say +does not apply to them, let us see what they themselves +have made of the facts of secondary sexual +characters—which, of course, are for the most part +specific characters—in relation to the doctrine of +utility.</p> + +<p>Mr. Wallace himself, in his last work, quotes +approvingly a letter which he received in 1869 from +the Rev. O Pickard-Cambridge, as follows:—</p> + +<blockquote><p>"I myself doubt that particular application of the Darwinian +theory which attributes male peculiarities of form, structure, +colour, and ornament to female appetency or predilection. +There is, it seems to me, undoubtedly something in the male +organization of a special and sexual nature, which, of its own +vital force, develops the remarkable male peculiarities so +commonly seen, <i>and of no imaginable use to that sex</i>. In as far +as these peculiarities show a great vital power, they point out +to us the finest and strongest individuals of the sex, and show +us which of them would most certainly appropriate to themselves +the best and greatest number of females, and leave behind them +the strongest and greatest number of progeny. And here would +come in, as it appears to me, the proper application of Darwin's<span class="pagenum"><a name="Page_222" id="Page_222">[Pg 222]</a></span> +theory of Natural Selection; <i>for the possessors of greatest vital +power being those most frequently produced and reproduced, the +external signs of it would go on developing in an ever increasing +exaggeration</i>, only to be checked where it became really +detrimental in some respect or other to the individual<a name="FNanchor_117_117" id="FNanchor_117_117"></a><a href="#Footnote_117_117" class="fnanchor">[117]</a>."</p></blockquote> + +<p>Here then the idea is, as more fully expressed by +Mr. Wallace in the context, that all the innumerable, +frequently considerable, and generally elaborate "peculiarities +of form, structure, colour, and ornament," +which Darwin attributed to sexual selection, are really +due to "the laws of growth." Diverse, definite, and +constant though these specific peculiarities be, they +are all but the accidental or adventitious accompaniments +of "vigour," or "vital power," due to natural +selection. Now, without waiting to dispute this view, +which has already been dealt with in the chapter +on Sexual Selection in Part I, it necessarily follows +that "a large proportional number of specific characters," +which, while presenting "no imaginable use," +are very much less remarkable, less considerable, less +elaborate, &c., must likewise be due to this "correlation +with vital power." But if the principle of correlation +is to be extended in this vague and general manner, it +appears to me that the difference between Mr. Wallace +and myself, with respect to the principle of utility, is +abolished. For of course no one will dispute that +the prime condition to the occurrence of "specific +characters," whether useful or useless, is the existence +of some form which has been denominated a "species" +to present them; and this is merely another way of +saying that such characters cannot arise except in +correlation with a general fitness due to natural<span class="pagenum"><a name="Page_223" id="Page_223">[Pg 223]</a></span> +selection. Or, to put the case in Mr. Wallace's +own words—"This development [of useless specific +characters] will necessarily proceed by the agency of +natural selection [as a necessary condition] <i>and the +general laws which determine the production of colour +and of ornamental appendages</i>." The case, therefore, +is just the same as if one were to say, for example, +that all the ailments of animals and plants proceed +from correlation with life (as a necessary condition), +"and the general laws which determine the production" +of ill-health, or of specific disease. In short, the +word "correlation" is here used in a totally different +sense from that in which it is used by Darwin, and in +which it is elsewhere used by Wallace for the purpose +of sustaining his doctrine of specific characters as +necessarily useful. To say that a useless character +A is correlated with a useful one B, is a very different +thing from saying that A is "correlated with vital +power," or with the general conditions to the existence +of the species to which it belongs. So far as the +present discussion is concerned, no exception need be +taken to the latter statement. For it simply surrenders +the doctrine against which I am contending.</p> + + +<h3>IV. <i>Isolation.</i></h3> + +<p>It is the opinion of many naturalists who are +well entitled to have an opinion upon the subject, +that, in the words of Mr. Dixon, "Isolation can +preserve a non-beneficial as effectually as natural +selection can preserve a beneficial variation<a name="FNanchor_118_118" id="FNanchor_118_118"></a><a href="#Footnote_118_118" class="fnanchor">[118]</a>." The +ground on which this doctrine rests is thus clearly<span class="pagenum"><a name="Page_224" id="Page_224">[Pg 224]</a></span> +set forth by Mr. Gulick:—"The fundamental cause +of this seems to lie in the fact that no two portions of +a species possess exactly the same average characters; +and, therefore, that the initial differences are for +ever reacting on the environment and on each other +in such a way as to ensure increasing divergence +in each generation, as long as the individuals of +the two groups are kept from intergenerating<a name="FNanchor_119_119" id="FNanchor_119_119"></a><a href="#Footnote_119_119" class="fnanchor">[119]</a>." In +other words, as soon as a portion of a species is +separated from the rest of that species, so that +breeding between the two portions is no longer +possible, the general average of characters in the +separated portion not being in all respects precisely +the same as it is in the other portion, the result of +in-breeding among all individuals of the separated +portion will eventually be different from that which +obtains in the other portion; so that, after a number +of generations, the separated portion may become +a distinct species from the effect of isolation alone. +Even without the aid of isolation, any original difference +of average characters may become, as it +were, magnified in successive generations, provided +that the divergence is not harmful to the individuals +presenting it, and that it occurs in a sufficient proportional +number of individuals not to be immediately +swamped by intercrossing. For, as Mr. Murphy +has pointed out, in accordance with Delbœuf's law, +"if, in any species, a number of individuals, bearing +a ratio not infinitely small to the entire number of +births, are in every generation born with a particular +variation which is neither beneficial nor injurious,<span class="pagenum"><a name="Page_225" id="Page_225">[Pg 225]</a></span> +and if it be not counteracted by reversion, then +the proportion of the new variety to the original +form will increase till it approaches indefinitely +near to equality<a name="FNanchor_120_120" id="FNanchor_120_120"></a><a href="#Footnote_120_120" class="fnanchor">[120]</a>." Now even Mr. Wallace himself +allows that this must be the case; and thinks that in +these considerations we may find an explanation of +the existence of certain definite varieties, such as +the melanic form of the jaguar, the brindled or ring-eyed +guillemot, &c. But, on the other hand, he +thinks that such varieties must always be unstable, +and continually produced in varying proportions +from the parent forms. We need not, however, +wait to dispute this arbitrary assumption, because +we can see that it fails, even as an assumption, in +all cases where the superadded influence of isolation +is concerned. Here there is nothing to intercept +the original tendency to divergent evolution, which +arises directly out of the initially different average +of qualities presented by the isolated section of the +species, as compared with the rest of that species<a name="FNanchor_121_121" id="FNanchor_121_121"></a><a href="#Footnote_121_121" class="fnanchor">[121]</a>.</p> + +<p><span class="pagenum"><a name="Page_226" id="Page_226">[Pg 226]</a></span>As we shall have to consider the important principle +of isolation more fully on a subsequent occasion, +I need not deal with it in the present connexion, +further than to remark that in this principle we have +what appears to me a full and adequate condition to +the rise and continuance of specific characters which +need not necessarily be adaptive characters. And, when +we come to consider the facts of isolation more closely, +we shall find superabundant evidence of this having +actually been the case.</p> + + +<h3>V. <i>Laws of Growth.</i></h3> + +<p>Under this general term Darwin included the operation +of all unknown causes internal to organisms +leading to modifications of form or structure—such +modifications, therefore, appearing to arise, as he +says "spontaneously," or without reference to utility. +That he attributed no small importance to the operation<span class="pagenum"><a name="Page_227" id="Page_227">[Pg 227]</a></span> +of these principles is evident from the last +edition of the <i>Origin of Species</i>. But as these "laws +of growth" refer to causes confessedly unknown, +I will not occupy space by discussing this division +of our subject—further than to observe that, as we +shall subsequently see, many of the facts which +fall under it are so irreconcilably adverse to the +Wallacean doctrine of specific characters as universally +adaptive, that in the face of them Mr. Wallace +himself appears at times to abandon his doctrine +<i>in toto</i>.</p> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_228" id="Page_228">[Pg 228]</a></p> + + + + +<h2>CHAPTER IX.<br /> +<span class="smcap">Characters as Adaptive and Specific</span><br /> +(<i>continued</i>).</h2> + + +<p>It must have appeared strange that hitherto I +should have failed to distinguish between "true +species" and merely "climatic varieties." But it +will conduce to clearness of discussion if we consider +our subject point by point. Therefore, having +now given a fair statement of the facts of climatic +variation, I propose to deal with their theoretical +implications—especially as regards the distinction +which naturalists are in the habit of drawing +between them and so-called true species.</p> + +<p>First of all, then, what is this distinction? Take, +for example, the case of the Porto Santo rabbits. +To almost every naturalist who reads what has been +said touching these animals, it will have appeared +that the connexion in which they are adduced is +wholly irrelevant to the question in debate. For, +it will be said that the very fact of the seemingly +specific differentiation of these animals having proved +to be illusory when some of them were restored to +their ancestral conditions, is proof that their peculiar +characters are not specific characters; but only what +Mr. Wallace would term "individual characters," or<span class="pagenum"><a name="Page_229" id="Page_229">[Pg 229]</a></span> +variations that are not <i>inherited</i>. And the same +remark applies to all the other cases which have been +adduced to show the generality and extent of climatic +variation, both in other animals and also in plants. +Why, then, it will be asked, commit the absurdity of +adducing such cases in the present discussion? Is it +not self-evident that however general, or however +considerable, such merely individual, or non-heritable, +variations may be, they cannot possibly have ever had +anything to do with the origin of <i>species</i>? Therefore, is +it not simply preposterous to so much as mention +them in relation to the question touching the utility +of specific characters?</p> + +<p>Well, whether or not it is absurd and preposterous +to consider climatic variations in connexion with the +origin of species, will depend, and depend exclusively, +on what it is that we are to understand by a species. +Hitherto I have assumed, for the sake of argument, +that we all know what is meant by a species. But +the time has now come for showing that such is far +from being the case. And as it would be clearly +absurd and preposterous to conclude anything with +regard to specific characters before agreeing upon +what we mean by a character as specific, I will +begin by giving all the logically possible definitions +of a species.</p> + +<p>1. <i>A group of individuals descended by way of natural +generation from an originally and specially created type.</i></p> + +<p>This definition may be taken as virtually obsolete.</p> + +<p>2. <i>A group of individuals which, while fully fertile</i> +inter se, <i>are sterile with all other individuals—or, at +any rate, do not generate fully fertile hybrids.</i></p> + +<p>This purely physiological definition is not nowadays<span class="pagenum"><a name="Page_230" id="Page_230">[Pg 230]</a></span> +entertained by any naturalist. Even though the +physiological distinction be allowed to count for +something in otherwise doubtful cases, no systematist +would constitute a species on such grounds alone. +Therefore we need not concern ourselves with this +definition, further than to observe that it is often +taken as more or less supplementary to each of the +following definitions.</p> + +<p>3. <i>A group of individuals which, however many +characters they share with other individuals, agree in +presenting one or more characters of a peculiar kind, +with some certain degree of distinctness.</i></p> + +<p>In this we have the definition which is practically +followed by all naturalists at the present time. But, +as we shall presently see more fully, it is an extremely +lax definition. For it is impossible to determine, by +any fixed and general rule, what degree of distinctness +on the part of peculiar characters is to be taken as +a uniform standard of specific separation. So long +as naturalists believed in special creation, they could +feel that by following this definition (3) they were +at any rate doing their best to tabulate very real +distinctions in nature—viz. between types as originally +produced by a supernatural cause, and as subsequently +more or less modified (i.e. within the limits imposed +by the test of cross-fertility) by natural causes. But +evolutionists are unable to hold any belief in such +real distinctions, being confessedly aware that all +distinctions between species and varieties are purely +artificial. So to speak, they well know that it is +they themselves who create species, by determining +round what degrees of differentiation their diagnostic +boundaries shall be drawn. And, seeing that these<span class="pagenum"><a name="Page_231" id="Page_231">[Pg 231]</a></span> +degrees of differentiation so frequently shade into +one another by indistinguishable stages (or, rather, +that they <i>always</i> do so, unless intermediate varieties +have perished), modern naturalists are well awake to +the impossibility of securing any approach to a uniform +standard of specific distinction. On this account +many of them feel a pressing need for some firmer +definition of a species than this one—which, in +point of fact, scarcely deserves to be regarded as +a definition at all, seeing that it does not formulate +any definite criterion of specific distinctness, +but leaves every man to follow his own standards +of discrimination. Now, as far as I can see, +there are only two definitions of a species which +will yield to evolutionists the steady and uniform +criterion required. These two definitions are as +follows.</p> + +<p>4. <i>A group of individuals which, however many +characters they share with other individuals, agree in +presenting one or more characters of a peculiar and +hereditary kind, with some certain degree of distinctness.</i></p> + +<p>It will be observed that this definition is exactly +the same as the last one, save in the addition of the +words "and hereditary." But, it is needless to say, +the addition of these words is of the highest importance, +inasmuch as it supplies exactly that objective +and rigid criterion of specific distinctness which the +preceding definition lacks. It immediately gets rid +of the otherwise hopeless wrangling over species as +"good" and "bad," or "true" and "climatic," of +which (as we have seen) Kerner's essay is such +a remarkable outcome. Therefore evolutionists have<span class="pagenum"><a name="Page_232" id="Page_232">[Pg 232]</a></span> +more and more grown to lay stress on the hereditary +character of such peculiarities as they select for +diagnostic features of specific distinctness. Indeed +it is not too much to say that, at the present time, +evolutionists in general recognize this character as, +theoretically, indispensable to the constitution of +a species. But it is likewise not too much to say +that, practically, no one of our systematic naturalists +has hitherto concerned himself with this matter. +At all events, I do not know of any who has ever +taken the trouble to ascertain by experiment, with +regard to any of the species which he has constituted, +whether the peculiar characters on which his +diagnoses have been founded are, or are not, hereditary. +Doubtless the labour of constituting (or, still +more, of <i>re</i>-constituting) species on such a basis of +experimental inquiry would be insuperable; while, +even if it could be accomplished, would prove undesirable, +on account of the chaos it would produce +in our specific nomenclature. But, all the same, we +must remember that this nomenclature as we now +have it—and, therefore, the partitioning of species as +we have now made them—has no reference to the +criterion of heredity. Our system of distinguishing +between species and varieties is not based upon the +definition which we are now considering, but upon +that which we last considered—frequently coupled, +to some undefinable extent, with No. 2.</p> + +<p>5. There is, however, yet another and closer definition, +which may be suggested by the ultra-Darwinian +school, who maintain the doctrine of natural selection +as the only possible cause of the origin of species, +namely:<span class="pagenum"><a name="Page_233" id="Page_233">[Pg 233]</a></span>—</p> + +<p><i>A group of individuals which, however many +characters they share with other individuals, agree +in presenting one or more characters of a peculiar, +hereditary, and adaptive kind, with some certain degree +of distinctness.</i></p> + +<p>Of course this definition rests upon the dogma of +utility as a necessary attribute of characters <i>quâ</i> +specific—i.e. the dogma against which the whole +of the present discussion is directed. Therefore +all I need say with reference to it is, that at +any rate it cannot be adduced in any argument +where the validity of its basal dogma is in question. +For it would be a mere begging of this question to +argue that every species must present at least one +peculiar and adaptive character, because, according +to definition, unless an organic type does present at +least one such character, it is not a specific type. +Moreover, and quite apart from this, it is to be hoped +that naturalists as a body will never consent to base +their diagnostic work on what at best must always +be a highly speculative extension of the Darwinian +theory. While, lastly, if they were to do so with +any sort of consistency, the precise adaptation which +each peculiar character subserves, and which because +of this adaptation is constituted a character of specific +distinction, would have to be determined by actual +observation. For no criterion of specific distinction +could be more vague and mischievous than this one, +if it were to be applied on grounds of mere inference +that such and such a character, because seemingly +constant, must "necessarily" be either useful, vestigial, +or correlated.</p> + +<p>Such then, as far as I can see, are all the<span class="pagenum"><a name="Page_234" id="Page_234">[Pg 234]</a></span> +definitions of a species that are logically possible<a name="FNanchor_122_122" id="FNanchor_122_122"></a><a href="#Footnote_122_122" class="fnanchor">[122]</a>. +Which of them is chosen by those who maintain +the necessary usefulness of all specific characters? +Observe, it is for those who maintain this doctrine +to choose their definition: it is not for me to do so. +My contention is, that the term does not admit of +any definition sufficiently close and constant to serve +as a basis for the doctrine in question—and this for +the simple reason that species-makers have never +agreed among themselves upon any criterion of specific +distinction. My opponents, on the other hand, are +clearly bound to take an opposite view, because, +unless they suppose that there is some such definition +of a species, they would be self-convicted of the +absurdity of maintaining a great generalization on +a confessedly untenable basis. For example, a few +years ago I was allowed to raise a debate in the +Biological Section of the British Association on the +question to which the present chapters are devoted. +But the debate ended as I had anticipated that it +must end. No one of the naturalists present could +give even the vaguest definition of what was meant by<span class="pagenum"><a name="Page_235" id="Page_235">[Pg 235]</a></span> +a species—or, consequently, of a character as specific. +On this account the debate ended in as complete +a destruction as was possible of the doctrine that +all the distinctive characters of every species must +necessarily be useful, vestigial, or correlated. For it +became unquestionable that the same generalization +admitted of being made, with the same degree of +effect, touching all the distinctive characters of every +"snark."</p> + +<p>Probably, however, it will be thought unfair to have +thus sprung a difficult question of definition in oral +debate. Therefore I allude to this fiasco at the +British Association, merely for the purpose of emphasizing +the necessity of agreeing upon some definition +of a species, before we can conclude anything with +regard to the generalization of specific characters as +necessarily due to natural selection. But when a +naturalist has had full time to consider this fundamental +matter of definition, and to decide on what +his own shall be, he cannot complain of unfairness on +the part of any one else who holds him to what he +thus says he means by a species. Now Mr. Wallace, +in his last work, has given a matured statement of +what it is that he means by a species. This, therefore, +I will take as the avowed basis of his doctrine +touching the necessary origin and maintenance of all +specific characters by natural selection. His definition +is as follows:—</p> + +<blockquote><p>"An assemblage of individuals which have become somewhat +modified in structure, form, and constitution, <i>so as to adapt them +to slightly different conditions of life</i>; which can be differentiated +from allied assemblages; which reproduce their like; which +usually breed together; and, perhaps, when crossed with their<span class="pagenum"><a name="Page_236" id="Page_236">[Pg 236]</a></span> +near allies, always produce offspring which are more or less sterile +<i>inter se</i><a name="FNanchor_123_123" id="FNanchor_123_123"></a><a href="#Footnote_123_123" class="fnanchor">[123]</a>."</p></blockquote> + +<p>From this definition the portion which I have +italicized must be omitted in the present discussion, +for the reasons already given while considering +definition No. 5. What remains is a combination of +Nos. 2 and 4. According to Mr. Wallace, therefore, +our criterion of a species is to be the heredity of +peculiar characters, combined, perhaps, with a more +or less exclusive fertility of the component individuals +<i>inter se</i>. This is the basis on which his generalization +of the utility of specific characters as necessary and +universal is reared. Here, then, we have something +definite to go upon, at all events as far as Mr. Wallace +is concerned. Let us see how far such a basis of +definition is competent to sustain his generalization.</p> + +<p>First of all it must be remarked that, as species +have actually been constituted by systematists, the +test of exclusive fertility does not apply. For my +own part I think this is to be regretted, because +I believe that such is the only natural—and therefore +the only firm—basis on which specific distinctions +can be reared. But, as previously observed, +this is not the view which has been taken by our +species-makers. At most they regard the physiological +criterion as but lending some additional weight +to their judgement upon morphological features, in +cases where it is doubtful whether the latter alone +are of sufficient distinctness to justify a recognition +of specific value. Or, conversely, if the morphological +features are clearly sufficient to justify such a recognition, +yet if it happens to be known that there is<span class="pagenum"><a name="Page_237" id="Page_237">[Pg 237]</a></span> +full fertility between the form presenting them and +other forms which do not, then the latter fact will +usually prevent naturalists from constituting the well +differentiated form a species on grounds of its morphological +features alone—as, for instance, in the case of +our domesticated varieties. In short, the physiological +criterion has not been employed with sufficient closeness +to admit of its being now comprised within any +practical definition of the term "species"—if by this +term we are to understand, not what any one may +think species <i>ought to be</i>, but what species actually +<i>are</i>, as they have been constituted for us by their +makers.</p> + +<p>From all this it follows that the definition of the +term "species" on which Mr. Wallace relies for his +deduction with respect to specific characters, is the +definition No. 4. In other words, omitting his <i>petitio +principii</i> and his allusion to the test of fertility, the +great criterion in his view is the criterion of Heredity. +And in this all other evolutionists, of whatever school, +will doubtless agree with him. They will recognize +that it is really the distinguishing test between +"climatic varieties" and "true species," so that however +widely or however constantly the former may +diverge from one another in regard to their peculiar +characters, they are not to be classed among the +latter unless their peculiar characters are likewise +hereditary characters.</p> + +<p>Now, if we are all agreed so far, the only question +that remains is whether or not this criterion of +Heredity is capable of supplying a basis for the +generalization, that all characters which have been +ranked as of specific value must necessarily be<span class="pagenum"><a name="Page_238" id="Page_238">[Pg 238]</a></span> +regarded as presenting also an adaptive, or life-serving, +value? I will now endeavour to show that +there are certain very good reasons for answering +this question in the negative.</p> + + +<h3>(A.)</h3> + +<p>In the first place, even if the modifications induced +by the direct action of a changed environment are +not hereditary, who is to know that they are not? +Assuredly not the botanist or zoologist who in +a particular area finds what he is fully entitled to +regard as a well-marked specific type. Only by +experiments in transposition could it be proved +that the modifications have been produced by local +conditions; and although the researches of many +experimentalists have shown how considerable and +how constant such modifications may be, where is the +systematic botanist who would ever think of transplanting +an apparently new species from one distant +area to another before he concludes that it is a new +species? Or where is the systematic zoologist who +would take the trouble to transport what appears +to be an obviously endemic species of animal from +one country to another before venturing to give it +a new specific name? No doubt, both in the case +of plants and animals, it is tacitly assumed that +constant differences, if sufficient in amount to be regarded +as specific differences are hereditary; but there +is not one case in a hundred where the validity of this +assumption has ever been tested by experiments +in transposition. Therefore naturalists are apt to +regard it as remarkable when the few experiments +which have been made in this direction are found<span class="pagenum"><a name="Page_239" id="Page_239">[Pg 239]</a></span> +to negative their assumption—for example, that +a diagnostic character in species of the genus <i>Hieratium</i> +is found by transplantation not to be hereditary, +or that the several named species of British trout +are similarly proved to be all "local varieties" of one +another. But, in point of fact, there ought to be +nothing to surprise us in such results—unless, indeed, +it is the unwarrantable nature of the assumption that +any given differences of size, form, colour, &c., which +naturalists may have regarded as of specific value, +are, on this account, hereditary. Indeed, so surprising +is this assumption in the face of what we +know touching both the extent and the constancy +of climatic variation, that it seems to me such a +naturalist as Kerner, who never considers the +criterion of heredity at all, is less assailable than those +who profess to constitute this their chief criterion +of specific distinction. For it is certain that whatever +their professions may have nowadays become, systematic +naturalists have never been in the habit +of really following this criterion. In theory they have +of late years attached more and more weight to +definition No. 4; but in practice they have always +adopted definition No. 3. The consequence is, that +in literally numberless cases (particularly in the +vegetable kingdom) "specific characters" are assumed +to be hereditary characters merely because systematic +naturalists have bestowed a specific name on the +form which presents them. Nor is this all. For, +conversely, even when it is known that constant morphological +characters are unquestionably hereditary +characters, if they happen to present but small +degrees of divergence from those of allied forms, then<span class="pagenum"><a name="Page_240" id="Page_240">[Pg 240]</a></span> +the form which presents them is not ranked as a +species, but as a constant variety. In other words, +when definitions 3 and 4 are found to clash, it is not +4, but 3, that is followed. In short, even up to the +present time, systematic naturalists play fast and +loose with the criterion of Heredity to such an +extent, that, as above observed, it has been rendered +wellnigh worthless in fact, whatever may be thought +of it in theory.</p> + +<p>Now, unless all this can be denied, what is the +use of representing that a species is distinguished +from a variety—"climatic" or otherwise—by the +fact that its constituent individuals "reproduce their +like"? We are not here engaged on any abstract +question of what might have been the best principles +of specific distinction for naturalists to have adopted. +We are engaged on the practical question of the +principles which they actually have adopted. And +of these principles the reproduction of like by like, +under all circumstances of environment, has been +virtually ignored.</p> + + +<h3>(B.)</h3> + +<p>In the second place, supposing that the criterion +of Heredity had been as universally and as rigidly +employed by our systematists in their work of constructing +species as it has been but occasionally and +loosely employed, could it be said that even then a basis +would have been furnished for the doctrine that all specific +characters must necessarily be useful characters? +Obviously not, and for the following reasons.</p> + +<p>It is admitted that climatic characters are not +necessarily—or even generally—useful characters.<span class="pagenum"><a name="Page_241" id="Page_241">[Pg 241]</a></span> +Consequently, if there be any reason for believing +that climatic characters may become in time hereditary +characters, the doctrine in question would +collapse, even supposing that all specific types were +to be re-constituted on a basis of experimental +inquiry, for the purpose of ascertaining which of +them conform to the test of Heredity. Now there +are very good reasons for believing that climatic +characters not unfrequently do become hereditary +characters; and it was mainly in view of those +reasons that I deemed it worth while to devote so +much space in the preceding chapter to the facts of +climatic variation. I will now state the reasons in +question under two different lines of argument.</p> + +<p>We are not as yet entitled to conclude definitely +against the possible inheritance of acquired characters. +Consequently, we are not as yet entitled +to assume that climatic characters—i. e. characters +acquired by converse with a new environment, continued, +say, since the last glacial period—can never +have become congenital characters. But, if they ever +have become congenital characters, they will have +become, at all events as a general rule, congenital +characters that are useless; for it is conceded that, +<i>quâ</i> climatic characters, they have not been due to +natural selection.</p> + +<p>Doubtless the followers of Weismann will repudiate +this line of argument, if not as entirely worthless, +at all events as too questionable to be of much +practical worth. But even to the followers of Weismann +it may be pointed out, that the Wallacean +doctrine of the origin of all specific characters by +means of natural selection was propounded many years<span class="pagenum"><a name="Page_242" id="Page_242">[Pg 242]</a></span> +before either Galton or Weismann had questioned +the transmission of acquired characters. However. +I allow that this line of argument has now become—for +the time being at all events—a dubious line, and +will therefore at once pass on to the second line, +which is not open to doubt from any quarter.</p> + +<p>Whether or not we accept Weismann's views, it +will here be convenient to employ his terminology, +since this will serve to convey the somewhat important +distinctions which it is now my object to +express.</p> + +<p>In the foregoing paragraphs, under heading (A), we +have seen that there must be "literally numberless +forms" which have been ranked as true species, +whose diagnostic characters are nevertheless not +congenital. In the case of plants especially, we know +that there must be large numbers of named species +which do not conform to the criterion of Heredity, +although we do not know which species they are. +For present purposes, however, it is enough for us +to know that there are many such named species, +where some change of environment has acted directly +and similarly on all the individual "somas" exposed +to it, without affecting their "germ-plasms," or the +material bases of their hereditary qualities. For named +species of this kind we may employ the term <i>somatogenetic +species</i>.</p> + +<p>But now, if there are any cases where a change of +environment does act on the germ-plasms exposed to +it, the result would be what we may call <i>blastogenetic +species</i>—i.e. species which conform to the +criterion of Heredity, and would therefore be ranked +by all naturalists as "true species." It would not<span class="pagenum"><a name="Page_243" id="Page_243">[Pg 243]</a></span> +signify in such a case whether the changed conditions +of life first affected the soma, and then, through +changed nutrition, the germ-plasm; or whether +from the first it directly affected the germ-plasm itself. +For in either case the result would be a "species," +which would continue to reproduce its peculiar +features by heredity.</p> + +<p>Now, the supposition that changed conditions of life +may thus affect the congenital endowments of germ-plasm +is not a gratuitous one. The sundry facts +already given in previous chapters are enough to +show that the origin of a blastogenetic species by the +direct action on germ-plasm of changed conditions +of life is, at all events, a possibility. And a little +further thought is enough to show that this possibility +becomes a probability—if not a virtual certainty. +Even Weismann—notwithstanding his desire to maintain, +as far as he possibly can, the "stability" of +germ-plasm—is obliged to allow that external conditions +acting on the organism may in some cases +modify the hereditary qualities of its germ-plasm, and +so, as he says, "determine the phyletic development +of its descendants." Again, we have seen that he is +compelled to interpret the results of his own experiments +on the climatic varieties of certain butterflies +by saying, "I cannot explain the facts otherwise than +by supposing the passive acquisition of characters +produced by direct influences of climate"; by which +he means that in this case the influence of climate +acts directly on the hereditary qualities of germ-plasm. +Lastly, and more generally, he says:—</p> + +<blockquote><p>"But although I hold it improbable that individual variability +can depend on a direct action of external influences upon the<span class="pagenum"><a name="Page_244" id="Page_244">[Pg 244]</a></span> +germ-cells and their contained germ-plasm, because—as +follows from sundry facts—the molecular structure of the +germ-plasm must be very difficult to change, yet it is by no +means to be implied that this structure may not possibly be +altered by influences of the same kind continuing for a very +long time. Thus it seems to me the possibility is not to be +rejected, that influences continued for a long time, that is, +for generations, such as temperature, kind of nourishment, +&c., which may affect the germ-cells as well as any other +part of the organism, may produce a change in the constitution +of the germ-plasm. But such influences would not then +produce individual variation, but would necessarily modify in +the same way all the individuals of a species living in a certain +district. It is possible, though it cannot be proved, that +many climatic varieties have arisen in this manner."</p></blockquote> + +<p>So far, then, we have testimony to this point, as it +were, from a reluctant witness. But if we have no +theory involving the "stability of germ-plasm" to +maintain, we can scarcely fail to see how susceptible +the germ-plasm is likely to prove to changed conditions +of life. For we know how eminently susceptible +it is in this respect when gauged by the +practical test of fertility; and as this is but an expression +of its extraordinarily complex character, it would +indeed be surprising if it were to enjoy any immunity +against modification by changed conditions of life. +We have seen in the foregoing chapter how frequently +and how considerably somatogenetic changes +are thus caused, so as to produce "somatogenetic +species"—or, where we happen to know that the +changes are not hereditary, "climatic varieties." But +the constitution of germ-plasm is much more complex +than that of any of the structures which are developed +therefrom. Consequently, the only wonder is that +hitherto experimentalists have not been more successful<span class="pagenum"><a name="Page_245" id="Page_245">[Pg 245]</a></span> +in producing "blastogenetic species" by artificial +changes of environment. Or, as Ray Lankester has +well stated this consideration, "It is not difficult to +suggest possible ways in which the changed conditions, +shown to be important by Darwin, could act +through the parental body upon the nuclear matter +of the egg-cell and sperm-cell, with its immensely +complex and therefore unstable constitution.... The +wonder is, not that [blastogenetic] variation occurs, +but that it is not excessive and monstrous in every +product of fertilization<a name="FNanchor_124_124" id="FNanchor_124_124"></a><a href="#Footnote_124_124" class="fnanchor">[124]</a>."</p> + +<p>If to this it should be objected that, as a matter +of fact, experimentalists have not been nearly so +successful in producing congenital modifications of +type by changed conditions of life as they have been +in thus producing merely somatic modifications; or if it +should be further objected that we have no evidence +at all in nature of a "blastogenetic species" having +been formed by means of climatic influences alone,—if +these objections were to be raised, they would admit +of the following answer.</p> + +<p>With regard to experiments, so few have thus far +been made upon the subject, that objections founded +on their negative results do not carry much weight—especially +when we remember that these results have +not been uniformly negative, but sometimes positive, +as shown in Chapter VI. With regard to plants and +animals in a state of nature, the objection is wholly +futile, for the simple reason that in as many cases as +changed conditions of life may have caused an hereditary +change of specific type, there is now no means<span class="pagenum"><a name="Page_246" id="Page_246">[Pg 246]</a></span> +of obtaining "evidence" upon the subject. But we +are not on this account entitled to conclude against +the probability of such changes of specific type +having been more or less frequently thus produced. +And still less can we be on this account entitled to +conclude against the <i>possibility</i> of such a change +having ever occurred in any single instance. Yet +this is what must be concluded by any one who +maintains that the origin of all species—and, <i>a fortiori</i>, +of all specific characters—must <i>necessarily</i> have +been due to natural selection.</p> + +<p>Now, if all this be admitted—and I do not see how +it can be reasonably questioned—consider how important +its bearing becomes on the issue before us. If +germ-plasm (using this term for whatever it is that +constitutes the material basis of heredity) is ever +capable of having its congenital endowments altered +by the direct action of external conditions, the resulting +change of hereditary characters, whatever else +it may be, need not be an adaptive change. Indeed, +according to Weismann's theory of germ-plasm, the +chances must be infinitely against the change being +an adaptive one. On the theory of pangenesis—that +is to say, on the so-called Lamarckian principles—there +would be much more reason for entertaining the +possibly adaptive character of hereditary change due +to the direct action of the environment. Therefore +we arrive at this curious result. The more that we are +disposed to accept Weismann's theory of heredity, and +with it the corollary that natural selection is the sole +cause of adaptive modification in species the less are +we entitled to assume that all specific characters +must necessarily be adaptive. Seeing that in nature<span class="pagenum"><a name="Page_247" id="Page_247">[Pg 247]</a></span> +there are presumably many cases like those of Hoffmann's +plants, Weismann's butterflies, &c., where the +hereditary qualities of germ-plasm have (on his hypothesis) +been modified by changed conditions of life, +we are bound to believe that, in all cases where such +changes do not happen to be actively deleterious, +they will persist. And inasmuch as characters which +are only of "specific" value must be the characters +most easily—and therefore most frequently—induced +by any slight changes in the constitution of germ-plasm, +while, for the same reason (namely, that of +their trivial nature) they are least likely to prove +injurious, it follows that the less we believe in the +functionally-produced adaptations of Lamarck, the +more ought we to resist the assumption that all +specific characters must necessarily be adaptive +characters.</p> + +<hr class="tb" /> + +<p>Upon the whole, then, and with regard to the +direct action of external conditions, I conclude—not +only from general considerations, but also from special +facts or instances quite sufficient for the purpose—that +these must certainly give rise to immense numbers +of somatogenetic species on the one hand, and +probably to considerable numbers of blastogenetic +species on the other; that in neither case is there any +reason for supposing the distinctively "specific characters" +to be other than "neutral" or "indifferent"; +while there are the best of reasons for concluding the +contrary. So that, under this division of our subject +alone (B), there appears to be ample justification +for the statement that "a large proportional number +of specific characters" are in reality, as they are in<span class="pagenum"><a name="Page_248" id="Page_248">[Pg 248]</a></span> +appearance, destitute of significance from a utilitarian +point of view.</p> + + +<h3>(C.)</h3> + +<p>Thus far in the present chapter we have been +dealing exclusively with the case of "climatic variation," +or change of specific type due to changes in +the external conditions of life. But it will be remembered +that, in the preceding chapter, allusion was +likewise made to changes of specific type due to +internal causes, or to what Darwin has called "the +nature of the organism." Under this division of +our subject I mentioned especially Sexual Selection, +which is supposed to arise in the aesthetic taste +of animals themselves; Isolation, which is supposed +to originate new types by allowing the average +characters of an isolated section of an old type to +develop a new history of varietal change, as we shall +see more fully in the ensuing part of this treatise; +and the Laws of Growth, which is a general term for +the operation of unknown causes of change incidental +to the living processes of organisms which present the +change.</p> + +<p>Now, under none of these divisions of our subject +can there be any question touching the criterion of +Heredity. For if new species—or even single specific +characters of new species—are ever produced by any +of these causes, they must certainly all "reproduce +their like." Therefore the only question which can +here obtain is as to whether or not such causes ever do +originate new species, or even so much as new specific +characters. Mr. Wallace, though not always consistently, +answers this question in the negative; but the<span class="pagenum"><a name="Page_249" id="Page_249">[Pg 249]</a></span> +great majority of naturalists follow Darwin by answering +it in the affirmative. And this is enough to show the +only point which we need at present concern ourselves +with showing—viz. that the question is, at the least, +an open one. For as long as this question is an open +one among believers in the theory of natural selection, +it must clearly be an unwarrantable deduction from +that theory, that all species, and <i>a fortiori</i> all specific +characters, are necessarily due to natural selection. +The deduction cannot be legitimately drawn until +the possibility of any other cause of specific modification +has been excluded. But the bare fact of the +question as just stated being still and at the least an +open question, is enough to prove that this possibility +has not been excluded. Therefore the deduction must +be, again on this ground alone (C), unwarrantable.</p> + +<hr class="tb" /> + +<p>Such are my several reasons—and it is to be +observed that they are all <i>independent</i> reasons—for +concluding that it makes no practical difference to +the present discussion whether or not we entertain +Heredity as a criterion of specific distinction. Seeing +that our species-makers have paid so little regard to +this criterion, it is neither absurd nor preposterous +to have adduced, in the preceding chapter, the facts +of climatic variation. On the contrary, as the definition +of "species" which has been practically followed +by our species-makers in No. 3, and not No. 4, these +facts form part and parcel of our subject. It is perfectly +certain that, in the vegetable kingdom at all +events, "a large proportional number" of specifically +diagnostic characters would be proved by experiment +to be "somatogenetic"; while there are numerous<span class="pagenum"><a name="Page_250" id="Page_250">[Pg 250]</a></span> +constant characters classed as varietal, although it is +well known that they are "blastogenetic." Moreover, +we can scarcely doubt that many specific characters +which are also hereditary characters owe their existence, +not to natural selection, but to the direct action +of external causes on the hereditary structure of +"germ-plasm"; while, even apart from this consideration, +there are at least three distinct and highly +general principles of specific change, which are accepted +by the great majority of Darwinists, and the +only common peculiarity of which is that they produce +hereditary changes of specific types without any +reference to the principle of utility.</p> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_251" id="Page_251">[Pg 251]</a></p> + + + + +<h2>CHAPTER X.<br /> +<span class="smcap">Characters as Adaptive and Specific</span><br /> +(<i>concluded</i>).</h2> + + +<p>Our subject is not yet exhausted. For it remains +to observe the consequences which arise from the +dogma of utility as the only <i>raison d'être</i> of species, +or of specific characters, when this dogma is applied +in practice by its own promoters.</p> + +<hr class="tb" /> + +<p>Any definition of "species"—excepting Nos. 1, 2, +and 5, which may here be disregarded—must needs +contain some such phrase as the one with which Nos. 3 +and 4 conclude. This is, that peculiar characters, in +order to be recognized as of specific value, must +present neither more nor less than "some certain +degree of distinctness." If they present more than +this degree of distinctness, the form, or forms, in +question must be ranked as generic; while if they +present less than this degree of distinctness, they +must be regarded as varietal—and this even if +they are known to be mutually sterile. What, +then, is this certain degree of distinctness? What +are its upper and lower limits? This question is +one that cannot be answered. From the very +nature of the case it is impossible to find a<span class="pagenum"><a name="Page_252" id="Page_252">[Pg 252]</a></span> +uniform standard of distinction whereby to draw +our boundary lines between varieties and species +on the one hand, or between species and genera on +the other. One or two quotations will be sufficient +to satisfy the general reader upon this point.</p> + +<p>Mr. Wallace himself alludes to "the great difficulty +that is felt by botanists in determining the +limits of species in many large genera," and gives +as examples well-known instances where systematic +botanists of the highest eminence differ hopelessly +in their respective estimates of "specific characters." +Thus:—</p> + +<blockquote><p>"Mr. Baker includes under a single species, Rosa canina, +no less than twenty-eight named varieties distinguished by +more or less constant characters, and often confined to special +localities, and to these are referred about seventy of the +species of British and continental botanists. Of the genus +Rubus or bramble, five British species are given in Bentham's +<i>Handbook of British Flora</i>, while in the fifth edition of +Babington's <i>Manual of British Botany</i>, published about the +same time, no less than forty-five species are described. Of +willows (Salix) the same two works enumerate fifteen and +thirty-one species respectively. The hawkweeds (Hieracium) +are equally puzzling, for while Mr. Bentham admits only seven +British species, Professor Babington describes no less than +seventy-two, besides several named varieties<a name="FNanchor_125_125" id="FNanchor_125_125"></a><a href="#Footnote_125_125" class="fnanchor">[125]</a>."</p></blockquote> + +<p>Mr. Wallace goes on to quote further instances, +such as that of Draba verna, which Jordan has +found to present, in the south of France alone, no less +than fifty-two permanent varieties, which all "come +true from seed, and thus present all the characteristics +of a true species"; so that, "as the plant is<span class="pagenum"><a name="Page_253" id="Page_253">[Pg 253]</a></span> +very common almost all over Europe, and ranges +from North America to the Himalayas, the number +of similar forms over this wide area would probably +have to be reckoned by hundreds, if not by thousands<a name="FNanchor_126_126" id="FNanchor_126_126"></a><a href="#Footnote_126_126" class="fnanchor">[126]</a>."</p> + +<p>One or two further quotations may be given to +the same general effect, selected from the writings of +specialists in their several departments.</p> + +<blockquote><p>"There is nothing that divides systematists more than what +constitutes a genus. Species that resemble each other more than +other species, is perhaps the best definition that can be given. +This is obviously an uncertain test, much depending on +individual judgement and experience; but that, in the evolution +of forms, such difficulties should arise in the limitation +of genera and species was inevitable. What is a generic +character in one may be only a specific character in another. +As an illustration of the uncertain importance of characters, +I may mention the weevil genus <i>Centrinus</i> in which the +leading characters in the classification of the family to which +it belongs are so mixed that systematists have been content +to keep the species together in a group that cannot be defined.... +No advantage or disadvantage is attached, apparently, +to any of the characters. There are about 200 species, all +American.</p> + +<p>The venation of the wings of insects is another example of +modifications without serving any special purpose. There is +no vein in certain Thripidae, and only a rudiment or a single +vein in Chalcididae. There are thousands of variations more +or less marked, some of the same type with comparatively +trivial variation, others presenting distinct types, even in the +same family, such genera, for example, as <i>Polyneura</i>, <i>Tettigetra</i>, +<i>Huechys</i>, &c. in the Cicadidae.</p> + +<p>Individual differences have often been regarded as distinctive +of species; varieties also are very deceptive, and races come +very near to species. A South-American beetle, <i>Arescus +histrio</i>, has varieties of yellow, red, and black, or these colours<span class="pagenum"><a name="Page_254" id="Page_254">[Pg 254]</a></span> +variously intermixed, and, what is very unusual, longitudinal +stripes in some and transverse bars in others, and all taken +in the same locality. Mr. A. G. Butler, of the British Museum, +is of opinion that 'what is generally understood by the term +species (that is to say, a well-defined, distinct, and constant type, +having no near allies) is non-existent in the Lepidoptera, and +that the nearest approach to it in this order is a constant, though +but slightly differing, rare or local form—that genera, in fact, consist +wholly of a gradational series of such forms (Ann. Mag. Nat. +Hist. 5, xix. 103)<a name="FNanchor_127_127" id="FNanchor_127_127"></a><a href="#Footnote_127_127" class="fnanchor">[127]</a>.'"</p></blockquote> + +<p>So much as regards entomology, and still living +forms. In illustration of the same principles in +connexion with palaeontological series, I may quote +Würtenberger, who says:—</p> + +<blockquote><p>"With respect to these fossil forms [i.e. multitudinous forms +of fossil Ammonites], it is quite immaterial whether a very +short or a somewhat longer part of any branch be dignified with +a separate name, and regarded as a species. The prickly +Ammonites, classed under the designation of Armata, are so +intimately connected that it becomes impossible to separate the +accepted species sharply from one another. The same remark +applies to the group of which the manifold forms are distinguished +by their ribbed shells, and are called Planulata<a name="FNanchor_128_128" id="FNanchor_128_128"></a><a href="#Footnote_128_128" class="fnanchor">[128]</a>."</p></blockquote> + +<p>I had here supplied a number of similar quotations +from writers in various other departments of systematic +work, but afterwards struck them out as superfluous. +For it is not to be anticipated that any competent +naturalist will nowadays dispute that the terms +"variety," "species," and "genus" stand for merely +conventional divisions, and that whether a given form +shall be ranked under one or the other of them is<span class="pagenum"><a name="Page_255" id="Page_255">[Pg 255]</a></span> +often no more than a matter of individual taste. +From the nature of the case there can be no objective, +and therefore no common, standards of delimitation. +This is true even as regards any one given department +of systematic work; but when we compare the +standards of delimitation which prevail in one department +with those which prevail in another, it becomes +evident that there is not so much as any attempt at +agreeing upon a common measure of specific distinction.</p> + +<p>But what, it may well be asked, is the use of thus +insisting upon well-known facts, which nobody will +dispute? Well, in the first place, we have already +seen, in the last chapter, that it is incumbent on those +who maintain that all species, or even all specific +characters, must be due to natural selection, to tell us +what they mean by a species, or by characters as +specific. If I am told to believe that the definite +quality A is a necessary attribute of B, and yet that +B is "not a distinct entity," but an undefinable abstraction, +I can only marvel that any one should +expect me to be so simple. But, without recurring +to this point, the use of insisting on the facts above +stated is, in the second place, that otherwise I cannot +suppose any general reader could believe them in view +of what is to follow. For he cannot but feel that the +cost of believing them is to render inexplicable the +mental processes of those naturalists who, in the face of +such facts, have deduced the following conclusions.</p> + +<p>The school of naturalists against which I am +contending maintains, as a generalization deduced +from the theory of natural selection, that all species, +or even all specific characters, must necessarily owe<span class="pagenum"><a name="Page_256" id="Page_256">[Pg 256]</a></span> +their origin to the principle of utility. Yet this same +school does not maintain any such generalization, +either with regard to varietal characters on the one +hand, or to generic characters on the other. On the +contrary, Professor Huxley, Mr. Wallace, and all +other naturalists who agree with them in refusing to +entertain so much as the abstract possibility of any +cause other than natural selection having been productive +of species, fully accept the fact of other +causes having been largely concerned in the production +of varieties, genera, families, and all higher groups, +or of the characters severally distinctive of each. +Indeed, Mr. Wallace does not question what appears +to me the extravagant estimate of Professor Cope, +that the non-adaptive characters distinctive of those +higher groups are fully equal, in point of numbers, to +the adaptive. But, surely, if the theory of evolution +by natural selection is, as we all agree, a true theory +of the origin of species, it must likewise be a true +theory of the origin of genera; and if it be supposed +essential to the integrity of the theory in its former +aspect that all specific characters should be held to +be useful, I fail to see how, in regard to its latter +aspect, we are so readily to surrender the necessary +usefulness of all generic characters. And exactly the +same remark applies to the case of constant "varieties," +where again the doctrine of utility as universal is not +maintained. Yet, according to the general theory of +evolution, constant varieties are what Darwin termed +"incipient species," while species are what may be +termed "incipient genera." Therefore, if the doctrine +of utility as universal be conceded to fail in the case +of varieties on the one hand and of genera on the<span class="pagenum"><a name="Page_257" id="Page_257">[Pg 257]</a></span> +other, where is the consistency in maintaining that it +must "necessarily" hold as regards the intermediate +division, species? Truly the shade of Darwin may +exclaim, "Save me from my friends." And truly +against logic of this description a follower of Darwin +must find it difficult to argue. If one's opponents +were believers in special creation, and therefore stood +upon some definite ground while maintaining this +difference between species and all other taxonomic +divisions, there would at least be some issue to argue +about. But when on the one hand it is conceded +that species are merely arbitrary divisions, which +differ in no respect as to the process of their evolution +from either varieties or genera, while on the other +hand it is affirmed that there is thus so great a +difference in the result, all we can say is that our +opponents are entangling themselves in the meshes +of a sheer contradiction.</p> + +<p>Or, otherwise stated, specific characters differ from +varietal characters in being, as a rule, more pronounced +and more constant: on this account advocates of +utility as universal apply the doctrine to species, +while they do not feel the "necessity" of applying it +to varieties. But now, generic and all higher characters +are even more constant and more pronounced +than specific characters—not to say, in many cases, +more generally diffused over a larger number of +organisms usually occupying larger areas. Therefore, +<i>a fortiori</i>, if for the reasons above stated evolutionists +regard it as a necessary deduction from the +theory of natural selection that all specific characters +must be useful, much more ought it to be +a necessary deduction from this theory that all generic,<span class="pagenum"><a name="Page_258" id="Page_258">[Pg 258]</a></span> +and still more all higher, characters must be useful. +But, as we have seen, this is not maintained by our +opponents. On the contrary, they draw the sharpest +distinction between specific and all other characters in +this respect, freely conceding that both those below +and those above them need not—and very often do +not—present any utilitarian significance.</p> + +<p>Although it appears to me that this doctrine is self-contradictory, +and on this ground alone might be +summarily dismissed, as it is now held in one or +other of its forms by many naturalists, I will give it +a more detailed consideration in both its parts—namely, +first with respect to the distinction between +varieties and species, and next with respect to the +distinction between species and genera.</p> + +<hr class="tb" /> + +<p>Until it can be shown that species are something +more than merely arbitrary divisions, due to the +disappearance of intermediate varietal links; that in +some way or another they <i>are</i> "definite entities," +which admit of being delineated by the application of +some uniform or general principles of definition; +that, in short, species have only then been classified +as such when it has been shown that the origin of +each has been due to the operation of causes which +have not been concerned in the production of varieties;—until +these things are shown, it clearly remains +a gratuitous dogma to maintain that forms which +have been called species differ from forms which have +been called varieties in the important respect, that +they (let alone each of all their distinctive characters) +must necessarily have been due to the principle of +utility. Yet, as we have seen, even Mr. Wallace<span class="pagenum"><a name="Page_259" id="Page_259">[Pg 259]</a></span> +allows that a species is "not a distinct entity," but +"an assemblage of individuals which have become +somewhat modified in structure, form, and constitution"; +while estimates of the kinds and degrees +of modification which are to be taken as of specific +value are conceded to be undefinable, fluctuating, and +in not a few cases almost ludicrously divergent.</p> + +<p>Perhaps one cannot more forcibly present the +rational value of this position than by noting the following +consequences of it. Mr. Gulick writes me that +while studying the land-shells of the Sandwich Islands, +and finding there a rich profusion of unique varieties, +in cases where the intermediate varieties were rare he +could himself have created a number of species by +simply throwing these intermediate varieties into his +fire. Now it follows from the dogma which we are +considering, that, by so doing, not only would he +have created new species, but at the same time +he would have proved them due to natural selection, +and endowed the diagnostic characters of each with +a "necessarily" adaptive meaning, which previously it +was not necessary that they should present. Before +his destruction of these intermediate varieties, he need +have felt himself under no obligation to assume that +any given character at either end of the series was +of utilitarian significance: but, after his destruction of +the intermediate forms, he could no longer entertain +any question upon the matter, under pain of being +denounced as a Darwinian heretic.</p> + +<p>Now the application is self-evident. It is a general +fact, which admits of no denial, that the more our +knowledge of any flora or fauna increases, the greater +is the number of intermediate forms which are<span class="pagenum"><a name="Page_260" id="Page_260">[Pg 260]</a></span> +brought to light, either as still existing or as having +once existed. Consequently, the more that such +knowledge increases, the more does our catalogue of +"species" diminish. As Kerner says, "bad species" +are always multiplying at the expense of "good +species"; or, as Oscar Schmidt (following Häckel) +similarly remarks, if we could know as much about +the latter as we do about the former, "all species, +without any exception, would become what species-makers +understand by 'bad species'<a name="FNanchor_129_129" id="FNanchor_129_129"></a><a href="#Footnote_129_129" class="fnanchor">[129]</a>." Hence we +see that, just as Mr. Gulick could have created good +species by secretly destroying his intermediate +varieties, so has Nature produced her "good species" +for the delectation of systematists. And just as Mr. +Gulick, by first hiding and afterwards revealing his +intermediate forms, could have made the self-same +characters in the first instance necessarily useful, but +ever afterwards presumably useless, so has Nature +caused the utility of diagnostic characters to vary +with our knowledge of her intermediate forms. It +belongs to the essence of our theory of descent, that +in <i>all</i> cases these intermediate forms must either be +now existing or have once existed; and, therefore, +that the work of species-makers consists in nothing +more than marking out the <i>lacunae</i> in our knowledge +of them. Yet we are bound to believe that wherever +these <i>lacunae</i> in our knowledge occur, there occurs +also the objective necessity of causation as utilitarian—a +necessity, however, which vanishes so soon as +our advancing information supplies the intermediate +forms in question. It may indeed appear strange that<span class="pagenum"><a name="Page_261" id="Page_261">[Pg 261]</a></span> +the utility or non-utility of organic structures should +thus depend on the accidents of human knowledge; +but this is the Darwinian faith, and he who doubts the +dogma is to be anathema.</p> + +<p>Turning next to the similar distinction which it +is sought to draw between species and genera, here +it will probably be urged, as I understand it to +be urged by Mr. Wallace, that generic characters +(and still more characters of families, orders, &c.) refer +back to so remote a state of things that utility +may have been present at their birth which has +disappeared in their maturity. In other words, it +is held that all generic characters were originally +specific characters; that as such they were all originally +of use; but that, after having been rendered +stable by heredity, many of them may have ceased +to be of service to the descendants of those species +in which they originated, and whose extinction has +now made it impossible to divine what that service +may have been.</p> + +<p>Now, in the first place; this is not the interpretation +adopted by Darwin. For instance, he expressly +contrasts such cases with those of vestigial or "rudimentary" +structures, pointing out that they differ +from vestigial structures in respect of their permanence. +One quotation will be sufficient to establish +the present point.</p> + +<blockquote><p>"A structure which has been developed through long-continued +selection, when it ceases to be of service to a species, +generally becomes variable, as we see with rudimentary organs, +for it will no longer be regulated by this same power of +selection. But when, from the nature of the organism and +of the conditions, modifications have been induced which are<span class="pagenum"><a name="Page_262" id="Page_262">[Pg 262]</a></span> +unimportant for the welfare of the species, they may be, and +apparently often have been, transmitted in nearly the same +state to numerous, otherwise modified, descendants<a name="FNanchor_130_130" id="FNanchor_130_130"></a><a href="#Footnote_130_130" class="fnanchor">[130]</a>."</p></blockquote> + +<p>Here, and in the context, we have a sufficiently +clear statement of Darwin's view—first, that unadaptive +characters may arise in <i>species</i> as "fluctuating +variations, which sooner or later become <i>constant</i> +through the nature of the organism and of surrounding +conditions, as well as through the intercrossing +of distinct individuals, but <i>not</i> through natural selection"<a name="FNanchor_131_131" id="FNanchor_131_131"></a><a href="#Footnote_131_131" class="fnanchor">[131]</a>; +second, that such unadaptive characters may +then be transmitted in this their stable condition to +species-progeny, so as to become distinctive of genera, +families, &c.; third, that, on account of such characters +not being afterwards liable to diverse adaptive +modifications in different branches of the species-progeny, +they are of more value as indicating lines +of pedigree than are characters which from the first +have been useful; and, lastly, they are therefore now +empirically recognized by systematists as of most +value in guiding the work of classification. To me +it appears that this view is not only perfectly rational +in itself, but likewise fully compatible with the theory +of natural selection—which, as I have previously +shown, is <i>primarily</i> a theory of adaptive characters, +and therefore not necessarily a theory of <i>all</i> specific +characters. But to those who think otherwise, it +must appear—and does appear—that there is something +wrong about such a view of the case—that +it was not consistent in the author of the <i>Origin of +Species</i> thus to refer non-adaptive generic characters +to a parentage of non-adaptive specific characters.<span class="pagenum"><a name="Page_263" id="Page_263">[Pg 263]</a></span> +Nevertheless, as a matter of fact, Darwin was perfectly +consistent in putting forth this view, because, unlike +Wallace, he was not under the sway of any antecedent +dogma erroneously deduced from the theory of +natural selection.</p> + +<p>Next without reference to Darwin's authority, let +us see for ourselves where the inconsistency really lies. +To allow that generic characters may be useless, while +denying that specific characters can ever be so (unless +correlated with others that are useful), involves an +appeal to the argument from ignorance touching +the ancestral habits, life-conditions, &c., of a parent +species now extinct. Well, even upon this assumption +of utility as obsolete, there remains to be explained the +"stability" of useless characters now distinctive of +genera, families, orders, and the rest. We know that +specific characters which have owed their origin to +utility and have afterwards ceased to present utility, +degenerate, become variable, inconstant, "rudimentary," +and finally disappear. Why, then, should these +things not happen with regard to useless generic +distinctions? Still more, why should they not happen +with regard to family, ordinal, and class distinctions? +On the lines against which I am arguing it would +appear impossible that any answer to this question +can be suggested. For what explanation can be +given of the contrast thus presented between the +obsolescence of specific characters where previous +utility is demonstrable, and the permanence of +higher characters whose previous utility is assumed? +As we have already seen, Mr. Wallace himself +employs this consideration of permanence and constancy +against the view that any cause other than<span class="pagenum"><a name="Page_264" id="Page_264">[Pg 264]</a></span> +natural selection can have been concerned in the +origin and maintenance of <i>specific</i> characters. But +he does not seem to see that the consideration cuts +two ways—and much more forcibly against his +views than in favour of them. For while, as already +shown in the chapter before last, it is sufficiently +easy to dispose of the consideration as Wallace uses +it (by simply pointing out with Darwin that any +causes other than natural selection which may have +been concerned in the genesis of <i>specific</i> characters, +must, if equally uniform in their operation, equally +give rise to permanence and constancy in their results); +on the other hand, it becomes impossible to explain +the stability of useless <i>generic</i> characters, if, as +Wallace's use of the argument requires, natural selection +is the only possible cause of stability. The +argument is one that cannot be played with fast +and loose. Either utility is the sole condition to +the stability of <i>any</i> diagnostic character (in which +case it is not open to Mr. Wallace to assume that +all <i>generic</i> or higher characters which are now useless +have owed their origin to a past utility); or +else utility is not the sole condition to stability +(in which case his use of the present argument in +relation to <i>specific</i> characters collapses). We have +seen, indeed, in the chapter before last, that his use +of the argument collapses anyhow, or quite irrespective +of his inconsistent attitude towards generic +characters, with which we were not then concerned. +But the point now is that, as a mere matter of logic, +the argument from stability as Wallace applies it +to the case of specific characters, is incompatible +with his argument that useless generic characters<span class="pagenum"><a name="Page_265" id="Page_265">[Pg 265]</a></span> +may originally have been useful specific characters. +It can scarcely be questioned that the transmutation +of a species into a genus must, as a rule, have +allowed time enough for a newly acquired—i.e. +peculiar specific-character—to show some signs of +undergoing degeneration, if, as supposed, the original +cause of its development and maintenance was withdrawn +when the parent species began to ramify into its +species-progeny. Yet, as Darwin says, "it is notorious +that specific characters are more variable than +generic<a name="FNanchor_132_132" id="FNanchor_132_132"></a><a href="#Footnote_132_132" class="fnanchor">[132]</a>." So that, upon the whole, I do not see +how on grounds of general reasoning it is logically +possible to maintain Mr. Wallace's distinction between +specific and generic characters in respect of necessary +utility.</p> + +<p>But now, and lastly, we shall reach the same +conclusion if, discarding all consideration of general +principles and formal reasoning, we fasten attention +upon certain particular cases, or concrete facts. +Thus, to select only two illustrations within the +limits of genera, it is a diagnostic feature of the +genus <i>Equus</i> that small warty callosities occur on +the legs. It is impossible to suggest any useful +function that is now discharged by these callosities +in any of the existing species of the genus. +If it be assumed that they must have been of +some use to the species from which the genus +originally sprang, the assumption, it seems to me, +can only be saved by further assuming that in existing +species of the genus these callosities are in a vestigial +condition—i. e. that in the original or parent +species they performed some function which is now<span class="pagenum"><a name="Page_266" id="Page_266">[Pg 266]</a></span> +obsolete. But against these assumptions there lies +the following fact. The callosities in question are +not similarly distributed through all existing species +of the genus. The horse has them upon all +his four legs, while other species have them only +upon two. Therefore, if all specific characters are +necessarily due to natural selection, it is manifest +that these callosities are <i>not</i> now vestigial: on the +contrary, they <i>must</i> still be—or, at best, have recently +been—of so much importance to all existing species +of the genus, that not only is it a matter of selection-value +to all these species that they should possess +these callosities; but it is even a matter of selection-value +to a horse that he should possess four of +them, while it is equally a matter of selection-value +to the ass that he should possess only two. Here, +it seems to me, we have once more the doctrine of +the necessary utility of specific characters reduced +to an absurdity; while at the same time we display +the incoherency of the distinction between specific +characters and generic characters in respect of this +doctrine. For the distinction in such a case amounts +to saying that a generic character, if evenly distributed +among all the species, need not be an adaptive +character; whereas, if any one of the species presents +it in a slightly different form, the character must +be, on this account, necessarily adaptive. In other +words, the uniformity with which a generic character +occurs among the species of the genus is taken to +remove that character from the necessarily useful +class, while the absence of such uniformity is taken +as proof that the character must be placed within +the necessarily useful class. Which is surely no less<span class="pagenum"><a name="Page_267" id="Page_267">[Pg 267]</a></span> +a <i>reductio ad absurdum</i> with regard to the generic +character than the one just presented with regard to +its variants as specific characters. And, of course, +this twofold absurdity is presented in all cases where +a generic character is unequally distributed among +the constituent species of a genus.</p> + +<div class="figcenter" style="width: 276px;"> +<img src="images/illus_279.jpg" width="276" height="202" alt="Lower Teeth of Orang" title="Lower Teeth of Orang" /> +<span class="caption"><span class="smcap">Fig. 4.</span>—Lower Teeth of Orang (after Tomes).</span></div> + +<p>But here is an illustration of another class of cases. +Mr. Tomes has shown that the molar teeth of the +Orang present an extraordinary and altogether superfluous +amount of attachment in their sockets—the fangs +being not only exceedingly long, and therefore deeply +buried in the jaw-bone, but also curving round one +another, so as still further to strengthen the whole<a name="FNanchor_133_133" id="FNanchor_133_133"></a><a href="#Footnote_133_133" class="fnanchor">[133]</a>. +In the allied genera of anthropoid apes there is no +such abnormal amount of attachment. Now, the +question is, of what conceivable use can it <i>ever</i> +have been, either to the existing genus, or to its +parent species, that such an abnormal amount of +attachment should obtain? It certainly is not required +to prevent dislocation of the teeth, seeing that +in all allied genera, and even in man himself, the<span class="pagenum"><a name="Page_268" id="Page_268">[Pg 268]</a></span> +amount of attachment is already so great that teeth +will break before they can be drawn by anything +short of a dentist's forceps. Therefore I conclude +that this peculiarity in the dentition of the genus +must have arisen in its parent species by way +of what Darwin calls a "fluctuating variation," without +utilitarian significance. And I adduce it in +the present connexion because the peculiarity is one +which is equally unamenable to a utilitarian explanation, +whether it happens to occur as a generic +or a specific character.</p> + +<p>Numberless similar cases might be quoted; but +probably enough has now been said to prove the +inconsistency of the distinction which our opponents +draw between specific and all higher characters +in respect of utility. In point of fact, a very +little thought is enough to show that no such +distinction admits of being drawn; and, therefore, +that any one who maintains the doctrine of utility +as universal in the case of specific characters, must +in consistency hold to the same doctrine in the case +of generic and all higher characters. And the fact +that our opponents are unable to do this becomes +a virtual confession on their part of the futility of +the generalization which they have propounded<a name="FNanchor_134_134" id="FNanchor_134_134"></a><a href="#Footnote_134_134" class="fnanchor">[134]</a>.</p> +<p><span class="pagenum"><a name="Page_269" id="Page_269">[Pg 269]</a></span></p> +<p>On what then do Mr. Wallace and his followers +rely for their great distinction between specific and +all other characters in respect of utility? This is +the final and fundamental question which I must +leave these naturalists themselves to answer; for my +whole contention is, that it is unanswerable. But +although I am satisfied that they have nothing on +which to base their generalization, it seems worth +while to conclude by showing yet one further point. +And this is, that these naturalists themselves, as soon +as they quit merely abstract assertions and come to +deal with actual facts, contradict their own generalization. +It is worth while to show this by means of +a few quotations, that we may perceive how impossible +it is for them to sustain their generalization in the +domain of fact.</p> + +<p>As it is desirable to be brief, I will confine myself +to quoting from Mr. Wallace.</p> + +<blockquote><p>"Colour may be looked upon as a necessary result of the +highly complex chemical constitution of animal tissues and +fluids. The blood, the bile, the bones, the fat, and other +tissues have characteristic, and often brilliant colours, which +we cannot suppose to have been determined for any special +purpose as colours, since they are usually concealed. The +external organs and integuments, would, by the same general +laws, naturally give rise to a greater variety of colour<a name="FNanchor_135_135" id="FNanchor_135_135"></a><a href="#Footnote_135_135" class="fnanchor">[135]</a>."</p></blockquote> + +<p>Surely comment is needless. Have the colour of +external organs and integuments nothing to do with<span class="pagenum"><a name="Page_270" id="Page_270">[Pg 270]</a></span> +the determining of specific distinctions by systematists? +Or, may we not rather ask, are there any +other "characters" which have had more to do with +their delineation of animal species? Therefore, if +"the external organs and integuments naturally give +rise to a greater variety of colours," for non-utilitarian +reasons, than is the case with internal organs and +tissues; while even the latter present, for similarly +non-utilitarian reasons, such variety and intensity of +colours as they do; must it not follow that, on the +ground of the "Laws of Growth" alone, Mr. Wallace +has conceded the entire case as regards "a large +proportional number of specific characters" being +non-adaptive—"spontaneous" in their occurrence, +and "meaningless" in their persistence?</p> + +<p>Once more:—</p> + +<blockquote><p>"The enormously lengthened plumes of the bird of paradise +and of the peacock, can, however, have no such use [i.e. for purposes +of defence], but must be rather injurious than beneficial +in the birds' ordinary life. The fact that they have been developed +to so great an extent in a few species is an indication +of such perfect adaptation to the conditions of existence, such +complete success in the battle for life, that there is, in the +adult male at all events, a surplus of strength, vitality, and +growth-power, which is able to expend itself in this way without +injury. That such is the case is shown by the great abundance +of most of the species which possess these wonderful +superfluities of plumage.... Why, in allied species, the +development of accessory plumes has taken different forms, we +are unable to say, except that it may be due to that individual +variability which has served as a starting-point for so much +of what seems to us strange in form, or fantastic in colour, +both in the animal and vegetable world<a name="FNanchor_136_136" id="FNanchor_136_136"></a><a href="#Footnote_136_136" class="fnanchor">[136]</a>."</p></blockquote> + +<p>Here, again, one need only ask, How can such statements<span class="pagenum"><a name="Page_271" id="Page_271">[Pg 271]</a></span> +be reconciled with the great dogma, "which is +indeed a necessary deduction from the theory of +Natural Selection, namely, that none of the definite +facts of organic nature, no special organ, no characteristic +form or marking can exist, but which must now +be, or once have been, <i>useful</i>"? Can it be said that +the plumes of a bird of paradise present "no characteristic +form," or the tail of a peacock "no characteristic +marking"? Can it be held that all the "fantastic +colours," which Darwin attributes to sexual selection, +and all the "strange forms" in the vegetable world +which present no conceivable reference to adaptation, +are to be ascribed to "individual variability" without +reference to utility, while at the same time it is held, +"as a necessary deduction from the theory of Natural +Selection," that <i>all</i> specific characters must be "<i>useful</i>"? +Or must we not conclude that we have here +a contradiction as direct as a contradiction can +well be<a name="FNanchor_137_137" id="FNanchor_137_137"></a><a href="#Footnote_137_137" class="fnanchor">[137]</a>?</p> + +<p>Nor is it any more possible to reconcile these +contradictory statements by an indefinite extension +of the term "correlation," than we found it to be in +the cases previously quoted. It might indeed be +logically possible, howsoever biologically absurd, to +attribute the tail of a peacock—with all its elaboration +of structure and pattern of colour, with all the +drain that its large size and weight makes upon the +vital resources of the bird, with all the increased +danger to which it exposes the bird by rendering it +more conspicuous, more easy of capture, &c.—to +correlation with some useful character peculiar to<span class="pagenum"><a name="Page_272" id="Page_272">[Pg 272]</a></span> +peacocks. But to say that it is due to correlation +with general "vitality," is merely to discharge the +doctrine of correlation of any assignable meaning. +Vitality, or "perfect adaptation to the conditions of +existence," is obviously a prime condition to the +occurrence of a peacock's tail, as it is to the occurrence +of a peacock itself; but this is quite a different +thing from saying that the specific characters which +are presented by a peacock's tail, although useless +in themselves, are correlated with some other and +useful specific characters of the same bird—as we saw +in a previous chapter with reference to secondary +sexual characters in general. Therefore, when Mr. +Wallace comes to the obvious question why it is that +even in "allied species," which must be in equally +"perfect adaptation to the conditions of existence," +there are no such "wonderful superfluities of plumage," +he falls back—as he previously fell back—on whatever +unknown <i>causes</i> it may have been which produced +the peacock's tail, when the primary <i>condition</i> +to their operation has been furnished by "complete +success in the battle for life."</p> + +<p>I have quoted the above passages, not so much for +the sake of exposing fundamental inconsistencies on +the part of an adversary, as for the sake of observing +that they constitute a much truer exposition of +"Darwinism" than do the contradictory views expressed +in some other parts of the work bearing that +title. For even if characters of so much size and elaboration +as the tail of a peacock, the plumes of a bird of +paradise &c., are admitted to be due to non-utilitarian +causes, much more must innumerable other characters +of incomparably less size and elaboration be mere<span class="pagenum"><a name="Page_273" id="Page_273">[Pg 273]</a></span> +"superfluities." Without being actually deleterious, +"a large proportional number of specific characters," +whose utility is not apparent, must <i>a fortiori</i> have been +due to "individual variation," to "general laws which +determine the production" of such characters—or, in +short, to some causes other than natural selection. +And this, I say, is a doctrine much more in harmony +with "Darwinism" than is the contradictory doctrine +which I am endeavouring to resist.</p> + +<p>But once again, and still more generally, after +saying of "the delicate tints of spring foliage, and the +intense hues of autumn," that "as colours they are +unadaptive, and appear to have no more relation to +the well-being of plants themselves than do the +colours of gems and minerals," Mr. Wallace proceeds +thus:—</p> + +<blockquote><p>"We may also include in the same category those algae +and fungi which have bright colours—the red snow of the +Arctic regions, the red, green, or purple seaweeds, the brilliant +scarlet, yellow, white or black agarics, and other fungi. All +these colours are probably the direct results of chemical composition +or molecular structure, and being thus normal products +of the vegetable organism, need no special explanation from +our present point of view; and the same remark will apply +to the varied tints of the bark of trunks, branches and twigs, +which are often of various shades of brown and green, or +even vivid reds and yellows<a name="FNanchor_138_138" id="FNanchor_138_138"></a><a href="#Footnote_138_138" class="fnanchor">[138]</a>."</p></blockquote> + +<p>Here, as Mr. Gulick has already observed, "Mr. +Wallace seems to admit that instead of useless specific +characters being unknown, they are so common and +so easily explained by 'the chemical constitution of +the organism' that they claim no special attention<a name="FNanchor_139_139" id="FNanchor_139_139"></a><a href="#Footnote_139_139" class="fnanchor">[139]</a>."<span class="pagenum"><a name="Page_274" id="Page_274">[Pg 274]</a></span> +And whatever answer Mr. Wallace may make to this +criticism, I do not see how he is to meet the point at +present before us—namely, that, upon his own showing, +there are in nature numberless instances of +"characters which are useless without being hurtful," +and which nevertheless present absolute "constancy." +If, in order to explain the contradiction, he should fall +back upon the principle of correlation, the case would +not be in any way improved. For, here again, if the +term correlation were extended so as to include "the +chemical constitution or the molecular structure of +the organism," it would thereby be extended so as to +discharge all Darwinian significance from the term.</p> + + +<h3><i>Summary.</i></h3> + +<p>I will conclude this discussion of the Utility +question by recapitulating the main points in an +order somewhat different from that in which they +have been presented in the foregoing chapters. Such +a variation may render their mutual connexions more +apparent. But it is only to the main points that +allusion will here be made, and, in order the better +to show their independent character, I will separately +number them.</p> + +<hr class="tb" /> + +<p>1. The doctrine of utility as universal, whether +with respect to species only or likewise with respect +to specific characters, is confessedly an <i>a priori</i> +doctrine, deduced by way of general reasoning from +the theory of natural selection.</p> + +<p>2. Being thus founded exclusively on grounds of +deduction, the doctrine cannot be combated by any<span class="pagenum"><a name="Page_275" id="Page_275">[Pg 275]</a></span> +appeal to facts. For this question is not one of fact: +it is a question of reasoning. The treatment of our +subject matter is logical: not biological.</p> + +<p>3. The doctrine is both universal and absolute. +According to one form of it <i>all</i> species, and according +to another form of it <i>all</i> specific characters, must +<i>necessarily</i> be due to the principle of utility.</p> + +<p>4. The doctrine in both its forms is deduced from +a definition of the theory of natural selection as +a theory, and the sole theory, of the origin of <i>species</i>; +but, as Professor Huxley has already shown, it does +not really follow, even from this definition, that all +specific <i>characters</i> must be "necessarily useful." +Hence the two forms of the doctrine, although coincident +with regard to species, are at variance with +one another in respect of specific characters. Thus +far, of course, I agree with Professor Huxley; but +if I have been successful in showing that the above +definition of the theory of natural selection is logically +fallacious, it follows that the doctrine in both its +forms is radically erroneous. The theory of natural +selection is not, accurately speaking, a theory of the +origin of species: it is a theory of the origin and +cumulative development of adaptations, to whatever +order of taxonomic division these may happen to +belong. Thus the premisses of the deduction which +we are considering collapse: the principle of utility +is shown not to have any other or further reference +to species, or to specific characters, than it has to +fixed varieties, genera, families, &c., or to the characters +severally distinctive of each.</p> + +<p>5. But, quitting all such antecedent considerations, +we next proceeded to examine the doctrine<span class="pagenum"><a name="Page_276" id="Page_276">[Pg 276]</a></span> +<i>a posteriori</i>, taking the arguments which have been +advanced in favour of the doctrine, other than those +which rest upon the fallacious definition. These +arguments, as presented by Mr. Wallace, are two in +number.</p> + +<p>First, it is represented that natural selection must +occupy the whole field, because no other principle +of change can be allowed to operate in the presence +of natural selection. Now I fully agree that this +statement holds as regards any principle of change +which is deleterious, but I cannot agree that it does +so as regards any such principle which is merely +neutral. No reason has ever been shown why natural +selection should interfere with "indifferent" characters—to +adopt Professor Huxley's term—supposing such +to have been produced by any of the agencies which +we shall presently have to name. Therefore this +argument—or rather assertion—goes for nothing.</p> + +<p>Mr. Wallace's second argument is, that utility is +the only principle which can endow specific characters +with their characteristic stability. But this again +is mere assertion. Moreover, it is assertion opposed +alike to common sense and to observable fact. It +is opposed to common sense, because it is obvious +that any other principle would equally confer stability +on characters due to it, provided that its action is +constant, as Darwin expressly held. Again, this +argument is opposed to fact, because we know of +thousands of cases where peculiar characters are +stable, which, nevertheless, cannot possibly be due +to natural selection. Of such are the Porto Santo +rabbits, the niata cattle, the ducks in St. James' +Park, turkeys, dogs, horses, &c., and, in the case of<span class="pagenum"><a name="Page_277" id="Page_277">[Pg 277]</a></span> +plants, wheat, cabbage, maize, &c., as well as all +the hosts of climatic varieties, both of animals and +plants, in a state of nature. Indeed, on taking a +wide survey of the facts, we do not find that the +principle of utility is any better able to confer +stability of character than are many other principles, +both known and unknown. Nay, it is positively less +able to do so than are some of these other principles. +Darwin gives two very probable reasons for this +fact; but I need not quote them a second time. It +is enough to have seen that this argument from +stability or constancy is no less worthless than the +previous one. Yet these are the only two arguments +of a corroborative kind which Mr. Wallace adduces +whereby to sustain his "necessary deduction."</p> + +<p>6. At this point, therefore, it may well seem that +we need not have troubled ourselves any further +with a generalization which does not appear to have +anything to support it. And to this view of the +case I should myself agree, were it not that many +naturalists now entertain the doctrine as an essential +article of their Darwinian creed. Hence, I proceeded +to adduce considerations <i>per contra</i>.</p> + +<p>Seeing that the doctrine in question can only rest +on the assumption that there is no cause other than +natural selection which is capable of originating any +single species—if not even so much as any single +specific character—I began by examining this assumption. +It was shown first that, on merely antecedent +grounds, the assumption is "infinitely precarious." +There is absolutely no justification for the statement +that in all the varied and complex processes of +organic nature natural selection is the only possible<span class="pagenum"><a name="Page_278" id="Page_278">[Pg 278]</a></span> +cause of specific change. But, apart altogether +from this <i>a priori</i> refutation of the dogma, our +analysis went on to show that, in point of actual +fact, there are not a few well-known causes of high +generality, which, while having no connexion with +the principle of utility, are demonstrably capable +of originating species and specific characters—if by +"species" and "specific characters" we are to understand +organic types which are ranked as species, +and characters which are described as diagnostic +of species. Such causes I grouped under five different +headings, viz. Climate, Food, Sexual Selection, +Isolation, and Laws of Growth. Sexual Selection +and Isolation are, indeed, repudiated by Mr. Wallace; +but, in common I believe with all biologists, he +accepts the other three groups of causes as fully +adequate to produce such kinds and degrees of +modification as are taken to constitute specific distinction. +And this is amply sufficient for our present +purposes. Besides, under the head of Sexual Selection, +it does not signify in the present connexion whether +or not we accept Darwin's theory on this subject. +For, in any case, the facts of secondary sexual characters +are indisputable: these characters are, for the +most part, specific characters: and they cannot be +explained by the principle of utility. Even Mr. +Wallace does not attempt to do so; and the explanation +which he does give is clearly incompatible +with his doctrine touching the necessarily life-serving +value of all specific characters. Lastly, the same has +to be said of the Laws of Growth. For we have just +seen that on the grounds of this principle likewise +Mr. Wallace abandons the doctrine in question. As<span class="pagenum"><a name="Page_279" id="Page_279">[Pg 279]</a></span> +regards Isolation, much more remains to be said in +the ensuing portion of this work, while, as regards +Climatic Variation, there are literally innumerable +cases where changes of specific type are known to +have been caused by this means.</p> + +<p>7. To the latter class of cases, however, it will be +objected that these changes of specific type, although +no doubt sufficiently "stable" so long as the changed +conditions remain constant, are found by experiment +not to be hereditary; and this clearly makes all the +difference between a true specific change and a merely +fictitious appearance of it.</p> + +<p>Well, in the first place, this objection can have +reference only to the first two of the five principles +above stated. It can have no reference to the last +three, because of these heredity constitutes the very +foundation. This consideration ought to be borne in +mind throughout. But now, in the second place, even +as regards changes produced by climate and food, the +reply is nugatory. And this for three reasons, as +follows.</p> + +<p>(<i>a</i>) No one is thus far entitled to conclude against +the possible transmission of acquired characters; and, +so long as there is even so much as a possibility of +climatic (or any other admittedly non-utilitarian) +variations becoming in this way hereditary, the reply +before us merely begs the question.</p> + +<p>(<i>b</i>) Even supposing, for the sake of argument, that +acquired characters can never in any case become +congenital, there remains the strong probability—sanctioned +as such even by Weismann—that changed +conditions of life may not unfrequently act upon the +material of heredity itself, thus giving rise to specific<span class="pagenum"><a name="Page_280" id="Page_280">[Pg 280]</a></span> +changes which are from the first congenital, though +not utilitarian. Indeed, there are not a few facts +(Hoffmann's plants, Weismann's butterflies, &c.), +which can only be explained either in this way, or +as above (<i>a</i>). And in the present connexion it is +immaterial which of these alternative explanations +we choose to adopt, seeing that they equally +refute our opponents' objection. And not only +do these considerations—(<i>a</i>) and (<i>b</i>)—refute this +particular objection; they overturn on new and +independent grounds the whole of our opponents' +generalization. For the generalization is, that the +principle of utility, acting through natural selection, +is "necessarily" the sole principle which can be +concerned in hereditary changes of specific type. +But here we perceive both a possibility (<i>a</i>) and a +probability (<i>b</i>), if not indeed a certainty, that quite +other principles have been largely concerned in the +production of such changes.</p> + +<p>(<i>c</i>) Altogether apart from these considerations, +there remains a much more important one. For +the objection that fixed—or "stable"—climatic +varieties differ from true species in not being subject +to heredity, raises the question—What are we +to understand by a "species"? This question, which +was thus far purposely left in abeyance, had now +to be dealt with seriously. For it would clearly +be irrational in our opponents to make this highly +important generalization with regard to species and +specific characters, unless they are prepared to tell +us what they mean by species, and therefore by +characters as specific. In as far as there is any +ambiguity on this point it makes entirely for our<span class="pagenum"><a name="Page_281" id="Page_281">[Pg 281]</a></span> +side in the debate, because even any small degree +of uncertainty with regard to it would render the +generalization in question proportionally unsound. +Yet it is notorious that no word in existence is more +vague, or more impossible to define, than the word +"species." The very same men who at one time +pronounce their great generalization with regard to +species, at another time asseverate that "a species +is not a definite entity," but a merely abstract term, +serving to denote this that and the other organic type, +which this that and the other systematist regards +as deserving such a title. Moreover it is acknowledged +that systematists differ among themselves +to a wide extent as to the kinds and degrees of +peculiarity which entitle a given form to a specific +rank. Even in the same department of systematic +work much depends on merely individual taste, while +in different departments widely different standards +of delimination are in vogue. Hence, our <i>reductio +ad absurdum</i> consists in this—that whether a given +form is to be regarded as necessarily due to natural +selection, and whether all its distinctive characters +are to be regarded as necessarily utilitarian characters, +will often depend on whether it has been described by +naturalist A or by naturalist B. There is no one +criterion—there is not even any one set of criteria—agreed +upon by naturalists for the construction of +specific types. In particular, as regards the principle +of heredity, it is not known of one named species +in twenty—probably not in a hundred—whether its +diagnostic characters are hereditary characters; while, +on the other hand, even in cases where experiment +has proved "constant varieties" to be hereditary—and<span class="pagenum"><a name="Page_282" id="Page_282">[Pg 282]</a></span> +even also cross-sterile with allied varieties—it is +only some three or four living botanists who for these +reasons advocate the elevation of such varieties to +the rank of species. In short, as we are not engaged on +any abstract question touching the principles on which +species ought to have been constituted by their makers, +but upon the actual manner in which they have been, +the criterion of heredity must needs be disregarded in +the present discussion, as it has been in the work of +systematists. And the result of this is, that any +objection to our introducing the facts of climatic variation +in the present discussion is excluded. In particular, +so far as any question of heredity is concerned, +all these facts are as assuredly as they are cogently +relevant. It is perfectly certain that there is "a large +proportional number" of named species—particularly +of plants—which further investigation would resolve +into climatic varieties. With the advance of knowledge, +"bad species" are always increasing at the +expense of "good species," so that we are now justified +in concluding with Kerner, Häckel, and other naturalists +best qualified to speak on this subject, that if we could +know as much about the past history and present relations +of the remaining good species as we do about the +bad, all the former, without exception, would become +resolved into the latter. In point of fact, and apart +altogether from the inductive experience on which this +conclusion is based, the conclusion follows "as a necessary +deduction" from the general theory of descent. +For this theory essentially consists in supposing +either the past or the present existence of intermediate +varietal forms in all cases, with the consequence +that "good species" serve merely to mark <i>lacunae</i> in<span class="pagenum"><a name="Page_283" id="Page_283">[Pg 283]</a></span> +our knowledge of what is everywhere a finely graduated +process of transmutation. Hence, if we place +this unquestionably "necessary deduction" from +the general theory of descent side by side with the +alleged "necessary deduction" from the theory of +natural selection, we cannot avoid the following +absurdity—Whether or not a given form is to be +regarded as necessarily due to natural selection, +and all its characters necessarily utilitarian, is to be +determined, and determined solely, by the mere +accident of our having found, or not having found, +either in a living or in a fossil state, its varietal +ancestry.</p> + +<p>8. But this leads us to consider the final and +crowning incongruities which have been dealt with in +the present chapter. For here we have seen, not +only that our opponents thus draw a hard and fast +line between "varieties" and "species" in regard +to "necessary origin" and "necessary utility," but that +they further draw a similar line between "species" +and "genera" in the same respects. Yet, in accordance +with the general theory of evolution, it is +plainly as impossible to draw any such line in the +one case as it is to do so in the other. Just as +fixed varieties are what Darwin called "incipient +species," so are species incipient genera, genera +incipient families, and so on. Evolutionists must +believe that the process of evolution is everywhere +the same. Nevertheless, while admitting all this, the +school of Huxley contradicts itself by alleging some +unintelligible exception in the case of "species," while +the school of Wallace presses this exception so as to +embrace "specific characters." Indeed Mr. Wallace,<span class="pagenum"><a name="Page_284" id="Page_284">[Pg 284]</a></span> +while maintaining that all specific characters must +necessarily be useful, maintains at the same time +that any number of varietal characters on the one +hand, and a good half of generic characters on +the other, are probably useless. Thus he contradicts +his argument from the "constancy of specific +characters" (seeing that generic characters are still +more constant), as later on we saw that he contradicts +his deductive generalization touching their +necessary utility, by giving a non-utilitarian explanation +of whole multitudes of specific characters. +I need not, however, again go over the ground so +recently traversed; but will conclude by once more +recurring to the only explanation which I have +been able to devise of the otherwise inexplicable +fact, that in regard to this subject so many naturalists +still continue to entangle themselves in the +meshes of absurdity and contradiction.</p> + +<hr class="tb" /> + +<p>The only conceivable explanation is, that these +naturalists have not yet wholly divested themselves +of the special creation theory. Although professing +to have discarded the belief that "species" are +"definite entities," differing in kind from "varieties" +on the one hand and from "genera" on the other, +these writers are still imbued with a vague survival +of that belief. They well know it to belong to the +very essence of their new theory that "species" +are but "pronounced varieties," or, should we prefer +it, "incipient genera"; but still they cannot altogether +escape the pre-Darwinian conception of species +as organic units, whose single mode of origin need +not extend to other taxonomic groups, and whose<span class="pagenum"><a name="Page_285" id="Page_285">[Pg 285]</a></span> +characters therefore present some exceptional significance +to the scientific naturalist. So to speak, such +divinity doth still hedge a species, that even in the +very act of declaring it but an idol of their own +creation, these naturalists bow before their fetish as +something that is unique—differing alike in its origin +and in its characters from the varieties beneath and +the genera above. The consequence is that they +have endeavoured to reconcile these incompatible +ideas by substituting the principle of natural selection +for that of super-natural creation, where the +particular case of "species" is concerned. In this +way, it vaguely seems to them, they are able to +save the doctrine of some one mode of origin as +appertaining to species, which need not "necessarily" +appertain to any other taxonomic division. All +other such divisions they regard, with their pre-Darwinian +forefathers, as merely artificial constructions; +but, likewise with these forefathers, they look +upon species as natural divisions, proved to be such +by a single and necessary mode of origin. Hence, +Mr. Wallace expressly defines a species with reference +to this single and necessary mode of origin (<i>see</i> above, +p. 235), although he must be well aware that there is +no better, or more frequent, proof of it in the case +of species, than there is in that of somewhat less +pronounced types on the one hand (fixed varieties), +or of more pronounced types on the other (genera, +families, &c.). Hence, also, the theory of natural +selection is defined as <i>par excellence</i> a theory of the +origin of species; it is taken as applying to the +particular case of the origin of species in a peculiarly +stringent manner, or in a manner which does not<span class="pagenum"><a name="Page_286" id="Page_286">[Pg 286]</a></span> +apply to the origin of any other groups. And +I believe that an important accessory reason of the +continuance of this view for more than thirty years +after the publication of the <i>Origin of Species by means +of Natural Selection</i>, is to be found in the title of that +work. "Natural Selection" has thus become verbally +associated with "Origin of Species," till it is thoughtlessly +felt that, in some way or another, natural selection +must have a peculiar reference to those artificially +delineated forms which stand anywhere between +a fixed variety and a so-called genus. This verbal +association has no doubt had the effect of still further +preserving the traditional halo of mystery which clings +to the idea of a "species." Hence it comes that the +title which Darwin chose—and, looking to the circumstances +of the time, wisely chose—for his great work, +has subsequently had the effect of fostering the very +idea which it was the object of that work to dissipate, +namely, that species are peculiar entities, which differ +more or less in origin or kind from all other taxonomic +groups. The full title of this work is—<i>The Origin of +Species by means of Natural Selection: or the Preservation +of Favoured Races in the Struggle for Life</i>. Now, +supposing that instead of this its author had chosen +some such title as the following:—<i>The Origin of +Organic Types by means of Adaptive Evolution: or +Survival of the Fittest Forms in the Struggle for Life</i>. +Of course this would have been a bad substitute from +various points of view; but could any objection have +been urged against it from our present point of view? +I do not see that there could. Yet, if such had been +the title, I have little doubt that we should never have +heard of those great generalizations with regard to<span class="pagenum"><a name="Page_287" id="Page_287">[Pg 287]</a></span> +species and specific characters, the futility of which it +has been the object of these chapters to expose.</p> + +<hr class="tb" /> + +<p>In conclusion, it only remains to reiterate that in +thus combating what appears to me plainly erroneous +deductions from the theory of natural selection, +I am in no wise combating that theory itself. On +the contrary, I hope that I am rendering it no unimportant +service by endeavouring to relieve it of +a parasitic growth—an accretion of false logic. +Regarding as I do the theory of natural selection as, +primarily, a theory of the origin (or cumulative +development) of adaptations, I see in merely non-adaptive +characters—be they "specific" or other—a +comparatively insignificant class of phenomena, +which may be due to a great variety of incidental +causes, without any further reference to the master-principle +of natural selection than that in the presence +of this principle none of these non-adaptive characters +can be actively deleterious. But that there may be +"any number of indifferent characters" it is no part +of the theory of natural selection to deny; and all +attempts to foist upon it <i>a priori</i> "deductions" opposed +alike to the facts of nature and to the logic of +the case, can only act to the detriment of the great +generalization which was expressly guarded from such +fallacies by the ever-careful judgement of Darwin.</p> + +<hr class="full" /> +<p class="pagenum"><a name="Page_289" id="Page_289">[Pg 289]</a></p> + + + + +<h2>APPENDICES AND NOTES</h2> +<hr class="chap" /> +<p class="pagenum"><a name="Page_291" id="Page_291">[Pg 291]</a></p> + + + + +<h2>APPENDIX I.<br /> +<span class="smcap">On Panmixia.</span></h2> + + +<p>There are several points of considerable theoretical importance +connected with Panmixia, which were omitted +from the text, in order to avoid distracting attention from +the main issue which is there under consideration. These +side issues may now be appropriately presented in the form +in which they were published in <i>Nature</i>, March 13, 1890<a name="FNanchor_140_140" id="FNanchor_140_140"></a><a href="#Footnote_140_140" class="fnanchor">[140]</a>. +After stating, in almost the same words, what has already +been said in Chapter X, this paper proceeds, with the exception +of a few verbal alterations, as follows.</p> + +<blockquote><p>"There is, however, one respect in which Professor Weismann's +statement of the principle of panmixia differs from that which was +considered by Mr. Darwin; and it is this difference of statement—which +amounts to an important difference of theory—that I +now wish to discuss.</p> + +<p>"The difference in question is, that while Professor Weismann +believes the cessation of selection to be capable of inducing degeneration +down to the almost complete disappearance of a rudimentary +organ, I have argued that, <i>unless assisted by some other +principle</i>, it can at most only reduce the degenerating organ to +considerably above one-half its original size—or probably not +through so much as one-quarter. The ground of this argument +(which is given in detail in the <i>Nature</i> articles of 1873-1874) is, +that panmixia depends for its action upon fortuitous variations +round an ever-diminishing average—the average thus diminishing +because it is no longer <i>sustained</i> by natural selection. But +although no longer sustained by <i>natural selection</i>, it does continue<span class="pagenum"><a name="Page_292" id="Page_292">[Pg 292]</a></span> +to be sustained by <i>heredity</i>; and therefore, as long as the +force of heredity persists unimpaired, fortuitous variations alone—or +variation which is no longer controlled by natural selection—cannot +reduce the dwindling organ to so much as one-half of +its original size; indeed, as above foreshadowed, the balance +between the positive force of heredity and the negative effects +of promiscuous variability will most likely be arrived at above +the middle line thus indicated. Only if for any reason the +force of heredity begins to fail can the average round which the +cessation of selection works become a progressively diminishing +average. In other words, so long as the original force of heredity +as regards the useless organ remains unimpaired, the mere withdrawal +of selection cannot reduce the organ much below the level +of efficiency above which it was previously <i>maintained</i> by the +<i>presence</i> of selection. If we take this level to be 80 or 90 per +cent. of the original size, cessation of selection will reduce the +organ through the 10 or 20 per cent., and there leave it fluctuating +about this average, unless for any reason the force of +heredity begins to fail—in which case, of course, the average will +progressively fall in proportion to the progressive weakening +of this force.</p> + +<p>"Now, according to my views, the force of heredity under such +circumstances is always bound to fail, and this for two reasons. +In the first place, it must usually happen that when an organ +becomes useless, natural selection as regards that organ will not +only <i>cease</i>, but become <i>reversed</i>. For the organ is now absorbing +nutriment, causing weight, occupying space, and so on, <i>uselessly</i>. +Hence, even if it be not also a source of actual danger, 'economy +of growth' will determine a reversal of selection against an organ +which is now not merely useless, but deleterious. And this degenerating +influence of the reversal of selection will throughout be +assisted by the cessation of selection, which will now be always +acting round a continuously sinking average. Nevertheless, +a point of balance will eventually be reached in this case, just as +it was in the previous case where the cessation of selection was +supposed to be working alone. For, where the reversal of selection +has reduced the diminishing organ to so minute a size that +its presence is no longer a source of detriment to the organism, +the cessation of selection will carry the reduction a small degree<span class="pagenum"><a name="Page_293" id="Page_293">[Pg 293]</a></span> +further; and then the organ will remain as a 'rudiment.' And +so it will remain permanently, unless there be some further reason +why the still remaining force of heredity should be abolished. +This further (or second) reason I found in the consideration that, +however enduring we may suppose the force of heredity to be, we +cannot suppose that it is actually everlasting; and, therefore, +that we may reasonably attribute the eventual disappearance of +rudimentary organs to the eventual failure of heredity itself. In +support of this view there is the fact that rudimentary organs, +although very persistent, are not everlasting. That they should +be very persistent is what we should expect, if the hold which +heredity has upon them is great in proportion to the time during +which they were originally useful, and thus firmly stamped upon +the organization by natural selection causing them to be strongly +inherited in the first instance. For example, we might expect +that it would be more difficult finally to eradicate the rudiment of +a wing than the rudiment of a feather; and accordingly we find +it a general rule that long-enduring rudiments are rudiments of +organs distinctive of the higher taxonomic divisions—i.e. of +organs which were longest in building up, and therefore longest +sustained in a state of working efficiency.</p> + +<p>"Thus, upon the whole, my view of the facts of degeneration +remains the same as it was when first published in these columns +seventeen years ago, and may be summarized as follows.</p> + +<p>"The cessation of selection when working alone (as it probably +does during the first centuries of its action upon structures +or colours which do not entail any danger to, or perceptible drain +upon, the nutritive resources of the organism) cannot cause degeneration +below, probably, some 10 to 20 per cent. But if from +the first the cessation of selection has been assisted by the +<i>reversal</i> of selection (on account of the degenerating structure +having originally been of a size sufficient to entail a perceptible +drain on the nutritive resources of the organism, having now +become a source of danger, and so forth), the two principles +acting together will continue to reduce the ever-diminishing +structure down to the point at which its presence is no longer +a perceptible disadvantage to the species. When that point is +reached, the reversal of selection will terminate, and the cessation +of selection will not then be able of itself to reduce the organ<span class="pagenum"><a name="Page_294" id="Page_294">[Pg 294]</a></span> +through more than at most a very few further percentages of its +original size. But, after this point has been reached, the now +total absence of selection, either for or against the organ, will +sooner or later entail this further and most important consequence, +a failure of heredity as regards the organ. So long as the +organ was of use, its efficiency was constantly <i>maintained</i> by +the <i>presence</i> of selection—which is merely another way of saying +that selection was constantly maintaining the force of heredity as +regards that organ. But as soon as the organ ceased to be of +use, selection ceased to maintain the force of heredity; and thus, +sooner or later, that force began to waver or fade. Now it is +this wavering or fading of the force of heredity, thus originally +due to the cessation of selection, that in turn co-operates with +the still continued cessation of selection in reducing the structure +below the level where its reduction was left by the actual reversal +of selection. So that from that level downwards the cessation +of selection, and the consequent failing of heredity, act and react +in their common work of causing obsolescence. In the case of +newly added characters, the force of heredity will be less than +in that of more anciently added characters; and thus we can +understand the long endurance of 'vestiges' characteristic +of the higher taxonomic divisions, as compared with those +characteristic of the lower. But in all cases, if time enough be +allowed under the cessation of selection, the force of heredity +will eventually fall to zero, when the hitherto obsolescent structure +will finally become obsolete. In cases of newly added and +comparatively trivial characters, with regard to which reversal +of selection is not likely to take place (e.g. slight differences of +colour between allied species), cessation of selection is likely to +be very soon assisted by a failure in the force of heredity; seeing +that such newly added characters will not be so strongly +inherited as are the more ancient characters distinctive of higher +taxonomic groups.</p> + +<p>"Let us now turn to Weismann's view of degeneration. First +of all, he has omitted to perceive that 'panmixia' alone (if unassisted +either by reversed selection or an inherent diminishing +of the force of heredity) cannot reduce a functionless organ +to the condition of a <i>rudiment</i>. Therefore he everywhere +represents panmixia (or the mere <i>cessation</i> of selection) as of<span class="pagenum"><a name="Page_295" id="Page_295">[Pg 295]</a></span> +itself sufficient to cause degeneration, say from 100 to 5, instead +of from 100 to 90 or 80, which, for the reasons above given, +appeared (and still appears) to me about the most that this +principle can accomplish, so long as the original force of heredity +continues unimpaired. No doubt we have here what must be +regarded as a mere oversight on the part of Professor Weismann; +but the oversight is rendered remarkable by the fact +that he <i>does</i> invoke the aid of reversed selection <i>in order to +explain the final disappearance of a rudiment</i>. Yet it is self-evident +that the reversal of selection must be much more active +during the initial than during the final stages of degeneration, +seeing that, <i>ex hypothesi</i>, the greater the degree of reduction +which has been attained the less must be the detriment arising +from any useless expenditure of nutrition, &c.</p> + +<p>"And this leads me to a second oversight in Professor Weismann's +statement, which is of more importance than the first. +For the place at which he does invoke the assistance of reversed +selection is exactly the place at which reversed selection must +necessarily have ceased to act. This place, as already explained, +is where an obsolescent organ has become rudimentary, +or, as above supposed, reduced to 5 per cent. of its original size; +and the reason why he invokes the aid of reversed selection at +this place is in order to save his doctrine of 'the stability of +germ-plasm.' That the force of heredity should finally become +exhausted if no longer <i>maintained</i> by the <i>presence</i> of selection, +is what Darwin's theory of perishable gemmules would lead +us to expect, while such a fact would be fatal to Weismann's +theory of an imperishable germ-plasm. Therefore he seeks to +explain the eventual failure of heredity (which is certainly a fact) +by supposing that after the point at which the cessation of selection +alone can no longer act (and which his first oversight has +placed some 80 per cent. too low), the reversal of selection will +begin to act directly against the force of heredity as regards the +diminishing organ, until such direct action of reversed selection +will have removed the organ altogether. Or, in his own words, +'The complete disappearance of a rudimentary organ can only +take place by the operation of natural selection; this principle +will lead to its diminution, inasmuch as the disappearing structure +takes the place and the nutriment of other useful and important<span class="pagenum"><a name="Page_296" id="Page_296">[Pg 296]</a></span> +organs.' That is to say, the rudimentary organ finally +disappears, not because the force of heredity is finally exhausted, +but because natural selection has begun to utilize this force +against the continuance of the organ—always picking out those +congenital variations of the organ which are of smallest size, and +thus, by its now <i>reversed</i> action, <i>reversing</i> the force of heredity +as regards the organ.</p> + +<p>"Now the oversight here is in not perceiving that the smaller +the disappearing structure becomes, the less hold must 'this +principle' of reversed selection retain upon it. As above +observed, during the earlier stages of reduction (or while co-operating +with the cessation of selection) the reversal of selection +will be at its <i>maximum</i> of efficiency; and, as the process +of diminution continues, a point must eventually be reached at +which the reversal of selection can no longer act. Take the +original mass of a now obsolescent organ in relation to that +of the entire organism of which it then formed a part to be +represented by the ratio 1:100. For the sake of argument we +may assume that the mass of the organism has throughout +remained constant, and that by 'mass' in both cases is meant +capacity for absorbing nutriment, causing weight, occupying +space, and so forth. Now, we may further assume that when +the mass of the organ stood to that of its organism in the ratio +of 1:100, natural selection was strongly reversed with respect +to the organ. But when this ratio fell to 1:1000, the activity of +such reversal must have become enormously diminished, even +if it still continued to exercise any influence at all. For we must +remember, on the one hand, that the reversal of selection can +only act as long as the presence of a diminishing organ continues +to be so injurious that variations in its size are matters of +life and death in the struggle for existence; and, on the other +hand, that natural selection in the case of the diminishing organ +does not have reference to the presence and the absence of the +organ, but only to such variations in its mass as any given +generation may supply. Now, the process of reduction does +not end even at 1:1000. It goes on to 1:10,000, and eventually +1:∞. Consequently, however great our faith in natural selection +may be, a point must eventually come for all of us at which +we can no longer believe that the reduction of an obsolescent<span class="pagenum"><a name="Page_297" id="Page_297">[Pg 297]</a></span> +organ is due to reversed selection. And I cannot doubt that if +Professor Weismann had sufficiently considered the matter, he +would not have committed himself to the statement that 'the +complete disappearance of a rudimentary organ can only take +place by the operation of natural selection.'</p> + +<p>"According to my view, the complete disappearance of a rudimentary +organ can only take place by the <i>cessation</i> of natural +selection, which permits the eventual exhaustion of heredity, +when heredity is thus simply left to itself. During all the earlier +stages of reduction, the cessation of selection was assisted in its +work by the reversal of selection; but when the rudiment +became too small for such assistance any longer to be supplied, +the rudiment persisted in that greatly reduced condition until +the force of heredity with regard to it was eventually worn +out. This appears to me, as it appeared in 1873, the only +reasonable conclusion that can be drawn from the facts. And +it is because this conclusion is fatal to Professor Weismann's +doctrine of the permanent 'stability' of germ-plasm, while +quite in accordance with all theories which belong to the family +of pangenesis, that I deem the facts of degeneration of great +importance as tests between these rival interpretations of the +facts of heredity. It is on this account that I have occupied so +much space with the foregoing discussion; and I shall be glad +to ascertain whether any of the followers of Professor Weismann +are able to controvert these views.</p> + +<p class="smcap" style="margin-left:80%;">"George J. Romanes."</p> + +<p>"P.S.—Since the above article was sent in, Professor Weismann +has published in these columns (February 6) his reply to a criticism +by Professor Vines (October 24, 1889). In this reply +he appears to have considerably modified his views on the +theory of degeneration; for while in his Essays he says (as in +the passage above quoted) that 'the complete disappearance of +a rudimentary organ can only take place by the operation +of natural selection'—i.e. only by the <i>reversal</i> of selection,—in +his reply to Professor Vines he says, 'I believe that I have +proved that organs no longer in use become rudimentary, and +must finally disappear, solely by 'panmixia'; not through the +direct action of disuse, but because natural selection no longer<span class="pagenum"><a name="Page_298" id="Page_298">[Pg 298]</a></span> +sustains their standard structure'—i.e. solely by the <i>cessation</i> +of selection. Obviously, there is here a flat contradiction. If +Professor Weismann now believes that a rudimentary organ +'must finally disappear <i>solely</i>' through the <i>withdrawal</i> of +selection, he has abandoned his previous belief that 'the +complete disappearance of a rudimentary organ can <i>only</i> take +place by the <i>operation</i> of selection.' And this change of belief +on his part is a matter of the highest importance to his system +of theories as a whole, since it betokens a surrender of his +doctrine of the 'stability' of germ-plasm—or of the virtually +everlasting persistence of the force of heredity, and the +consequent necessity for a reversal of this force itself (by natural +selection placing its premium on <i>minus</i> instead of on <i>plus</i> +variations), in order that a rudimentary organ should finally +disappear. In other words, it now seems he no longer believes +that the force of heredity in one direction (that of sustaining +a rudimentary organ) can only be abolished by the active influence +of natural selection determining this force in the opposite +direction (that of removing a rudimentary organ). It seems he +now believes that the force of heredity, if merely left to itself +by the withdrawal of natural selection altogether, will sooner or +later become exhausted through the mere lapse of time. This, +of course, is my own theory of the matter as originally published +in these columns; but I do not see how it is to be reconciled +with Professor Weismann's doctrine of so high a degree of +stability on the part of germ-plasm, that we must look to the +Protozoa and the Protophyta for the original source of congenital +variations as now exhibited by the Metazoa and Metaphyta. +Nevertheless, and so far as the philosophy of degeneration is +concerned, I shall be very glad if (as it now appears) Professor +Weismann's more recent contemplation has brought his principle +of panmixia into exact coincidence with that of my cessation +of selection."</p></blockquote> + +<p>Before passing on it may here be noted that, to any one +who believes in the inheritance of acquired characters, there +is open yet another hypothetical cause of degeneration, and +one to which the final disappearance of vestigial organs may +be attributed. Roux has shown in his work on <i>The Struggle<span class="pagenum"><a name="Page_299" id="Page_299">[Pg 299]</a></span> +for Existence between Parts of an Organism</i> that the principle +of selection must operate in every constituent tissue, and as +between every constituent cell of which an organism is composed. +Now, if an organ falls into disuse, its constituent cells +become worsted in their struggles with other cells in the +organism. Hence, degeneration of the disused organ may +progressively increase, quite independently of any struggle +for existence on the part of the organism as a whole. Consequently, +degeneration may proceed without any reference +to the principle of "economized nutrition"; and, if it does +so, and if the effects of its doing so are transmitted from +generation to generation, the disused organ will finally disappear +by means of Roux's principle.</p> + +<p>The long communication above quoted led to a still longer +correspondence in the pages of <i>Nature</i>. For Professor Ray +Lankester wrote<a name="FNanchor_141_141" id="FNanchor_141_141"></a><a href="#Footnote_141_141" class="fnanchor">[141]</a> to impugn the doctrine of panmixia, or cessation +of selection, <i>in toto</i>, arguing with much insistence that +"cessation of selection must be supplemented by economy of +growth in order to produce the results attributed to panmixia." +In other words, he denied that panmixia alone can cause +degeneration in any degree at all; at most, he said, it can +be but "a condition," or "a state," which occurs when an +organ or part ceases to be useful, and therefore falls under +the degenerating influence of active causes, such as economy +of nutrition. Or, in yet other words, he refused to recognize +that any degenerative process can be due to natural selection +as merely withdrawn: only when, besides being <i>withdrawn</i>, +natural selection is <i>reversed</i>, did he regard a degenerative +process as possible. As a result of the correspondence, +however, he eventually<a name="FNanchor_142_142" id="FNanchor_142_142"></a><a href="#Footnote_142_142" class="fnanchor">[142]</a> agreed that, if the "birth-mean" of +an organ, in respect either of size or complexity of structure, +be lower than the "selection-mean" while the organ is useful +(a fact which he does not dispute); then, if the organ ceases<span class="pagenum"><a name="Page_300" id="Page_300">[Pg 300]</a></span> +to be useful, it will degenerate by the withdrawal of selection +alone. Which, of course, is merely a re-statement of the +doctrine of panmixia, or cessation of selection, in somewhat +varied terminology—provided that the birth-mean be taken +over a number of generations, or not only over a few following +the selection-mean of the structure while still in its +highest state of efficiency. For the sake of brevity I will +hereafter speak of these "few following" generations by the +term of "first generations."</p> + +<p>It remains to consider the views of Professor Lloyd +Morgan upon the subject. In my opinion he is the +shrewdest, as well as the most logical critic that we have +in the field of Darwinian speculation; therefore, if possible, +I should like to arrive at a full agreement with him upon +this matter. His latest utterance with regard to it is as +follows:—</p> + +<blockquote><p>"To account for the diminution of organs or structures +no longer of use, apart from any inherited effects of disuse, +Mr. Romanes has invoked the Cessation of Selection; and +Mr. Francis Galton has, in another connexion, summarized the +effects of this cessation of selection in the convenient phrase +'Regression to Mediocrity.' This is the Panmixia of Professor +Weismann and his followers; but the phrase regression to +mediocrity through the cessation of selection appears to me +preferable. It is clear that so long as any organ or structure +is subject to natural selection through elimination, it is, if not +actually undergoing improvement, kept at a high standard of +efficiency through the elimination of all those individuals in +which the organ in question falls below the required standard. +But if, from change in the environment or any other cause, the +character in question ceases to be subject to selection, elimination +no longer takes place, and the high standard will no longer +be maintained. There will be reversion to mediocrity. The +probable amount of this reversion is at present a matter under +discussion<a name="FNanchor_143_143" id="FNanchor_143_143"></a><a href="#Footnote_143_143" class="fnanchor">[143]</a>."</p></blockquote> +<p><span class="pagenum"><a name="Page_301" id="Page_301">[Pg 301]</a></span></p> +<p>So far, then, Professor Lloyd Morgan is in complete +agreement with previous writers upon the subject. He does +not doubt that the cessation of selection must always be +a cause of degeneration: the only question is as to the +<i>potency</i> of this cause, or the <i>amount</i> of degeneration which +it is capable of effecting.</p> + +<p>Taking, first, the case of bulk or size of an organ, as +distinguished from its organization or complexity, we have +seen that Weismann represents the cessation of selection—even +if working quite alone, or without any assistance from +the reversal of selection—to be capable of reducing a fully +developed organ to the state of a rudiment, or even, if we +take his most recent view, of abolishing the organ <i>in toto</i>.</p> + +<p>Professor Lloyd Morgan, on the other hand, does not +think that the cessation of selection alone can cause reduction +further than the level of "mediocrity" in the first +generations—or, which is much the same thing, further than +the difference between the "birth-mean" and the "selection-mean" +of the first generations. This amount of reduction +he puts at 5 per cent., as "a very liberal estimate."</p> + +<p>Here, then, we have three estimates of the amount of +degeneration which can be produced by panmixia alone, +where mere size or bulk of an organ is concerned—say, +3 to 5 per cent., 10 to 20 per cent., and 95 per cent. to 0. +At first sight, these differences appear simply ludicrous; +but on seeking for the reasons of them, we find that they +are due to different views touching the manner in which +panmixia operates. The oversights which have led to +Weismann's extremely high estimate have already been +stated. The reason of the difference between the extremely +low estimate of Professor Lloyd Morgan, as compared with +my own intermediate one, is, that he supposes the power +of panmixia to become exhausted as soon as the level of +mediocrity of the first generations has become the general +level in succeeding generations. In my view, however, the<span class="pagenum"><a name="Page_302" id="Page_302">[Pg 302]</a></span> +level of mediocrity is itself a sinking level in successive +generations, with the result that there is no reason why the +reducing power of panmixia should ever become exhausted, +save that the more reduction it effects the greater is the +force of heredity which remains to be overcome, as +previously explained. Thus the only question between +Professor Lloyd Morgan and myself is—Does the level of +mediocrity fall in successive generations under the cessation +of selection, or does it remain permanently where it used to +be under the presence of selection? Does the "birth-mean" +remain constant throughout any number of generations, +notwithstanding that the sustaining influence of selection +has been withdrawn; or does it progressively sink as a consequence +of such withdrawal?</p> + +<p>In order to answer this question we had better begin by +considering now the case of organization of structure, as +distinguished from mere size of structure. Take any case +where a complex organ—such as a compound eye—has been +slowly elaborated by natural selection, and is it not self-evident +that, when natural selection is withdrawn, the complex +structure will deteriorate? In other words, the level of +mediocrity, say in the hundred thousandth generation after +the sustaining influence of natural selection has been withdrawn, +will not be so high as it was in the first generations. +For, by hypothesis, there is now no longer any elimination +of unfavourable variations, which may therefore perpetuate +themselves as regards any of the parts of this highly complex +mechanism; so that it is only a matter of time when the +mechanism must become disintegrated. I can scarcely +suppose that any one who considers the subject will question +this statement, and therefore I will not say anything that +might be said in the way of substantiating it. But, if the +statement be assented to, it follows that there is no need to +look for any cause of deterioration, further than the withdrawal +of selection—or cessation of the principle which (as<span class="pagenum"><a name="Page_303" id="Page_303">[Pg 303]</a></span> +we are supposing) had hitherto been the sole means of +maintaining efficient harmony among all the independently +variable parts of the highly complex structure.</p> + +<p>Now, I hold that the same thing is true, though in a lesser +degree, as regards degeneration of size. That there is no +difference <i>in kind</i> between the two cases, Professor Lloyd +Morgan implicitly allows; for what he says is—</p> + +<blockquote><p>"In any long-established character, such as wing-power in +birds, brain-development, the eyes of crustacea, &c., no shortcomer +in these respects would have been permitted by natural +selection to transmit his shortcomings for hundreds of generations. +All tendency to such shortcomings would, one would +suppose, have been bred out of the race. If after this long +process of selection there still remains a strong tendency to +deterioration, this tendency demands an explanation<a name="FNanchor_144_144" id="FNanchor_144_144"></a><a href="#Footnote_144_144" class="fnanchor">[144]</a>."</p></blockquote> + +<p>Here, then, deterioration as to size of structure (wings of +birds), and deterioration as to complexity of structure (brain +and eyes) are expressly put upon the same footing. Therefore, +if in the latter case the "tendency to deterioration" +does not "demand an explanation," beyond the fact that the +hitherto maintaining influence has been withdrawn, neither +is any such further explanation demanded in the former case. +Which is exactly my own view of the matter. It is also +Mr. Galton's view. For although, in the passage formerly +quoted, Professor Lloyd Morgan appears to think that by the +phrase "Regression to Mediocrity" Mr. Galton means to +indicate that panmixia can cause degeneration only as far as +the mediocrity level of the first generations, this, in point of +fact, is not what Galton means, nor is it what he says. The +phrase in question occurs "in another connexion," and, +indeed, in a different publication. But where he expressly +alludes to the cessation of selection, this is what he says. +The italics are mine.</p> +<p class="pagenum"><a name="Page_304" id="Page_304">[Pg 304]</a></p> + +<blockquote><p>"A special cause may be assigned for the effects of use in +causing hereditary <i>atrophy</i> of disused parts. It has already +been shown that all exceptionally developed organs tend to deteriorate: +consequently, those that are not <i>protected</i> by selection +will <i>dwindle</i>. The level of muscular efficiency in the wing +of a strongly flying bird [curiously enough, the same case that +is chosen by Professor Lloyd Morgan to illustrate his opposite +view], is like the level of water in the leaky vessel of a Danaid, +only secured to the race by <i>constant effort</i>, so to speak. <i>Let +the effort be relaxed ever so little, and the level immediately +falls<a name="FNanchor_145_145" id="FNanchor_145_145"></a><a href="#Footnote_145_145" class="fnanchor">[145]</a>.</i>"</p></blockquote> + +<p>I take it, then, that the burden of proof lies with Professor +Lloyd Morgan to show why the withdrawal of selection is +<i>not</i> sufficient to account for degeneration any further than +the mediocrity-level in the former presence of selection. +Why does "the strong tendency<a name="FNanchor_146_146" id="FNanchor_146_146"></a><a href="#Footnote_146_146" class="fnanchor">[146]</a> to deterioration demand +an explanation," further than the fact that when all variations +below the average in every generation are allowed to survive, +they must gradually lower the average itself through a series +of generations? To answer that any such tendency "would +have been bred out of the race" by the previous action of +selection, is to suppose that the function of selection is at an +end when once it has built up a structure to the highest +point of working efficiency,—that the presence of selection +is no longer required to <i>maintain</i> the structure at that point. +But it is enough to ask in reply—Why, under the cessation +of selection, does <i>complexity</i> of structure degenerate so +much more rapidly than <i>size</i> of structure? Why is it, for +instance, that "the eyes of crustacea" in dark caves have +entirely disappeared, while their foot-stalks (when originally +present) still remain? Can it be maintained that "for +hundreds of generations" natural selection was more intent<span class="pagenum"><a name="Page_305" id="Page_305">[Pg 305]</a></span> +on developing the foot-stalks than the eyes which were +mounted upon them—so that while the latter were left by +selection with "a strong tendency to deterioration," the +former have had this tendency "bred out in the race"<a name="FNanchor_147_147" id="FNanchor_147_147"></a><a href="#Footnote_147_147" class="fnanchor">[147]</a>?</p> + +<p>To sum up. There is now no question in any quarter +touching the fact that panmixia, or the cessation of selection, +is a true cause of degeneration. The only question is as to +the amount of degeneration which it is able to effect when +not assisted by the reversal of selection, or any other +cause of degeneration. Moreover, even with regard to this<span class="pagenum"><a name="Page_306" id="Page_306">[Pg 306]</a></span> +question of amount, there is no doubt on any side that +panmixia alone causes degeneration <i>more rapidly</i> where it +has to do with complexity of organization, than it does where +it is concerned with a mere reduction of mass.</p> + +<p>The question as to the amount of degeneration that is +caused by the cessation of selection alone is without any +practical importance where species in a state of nature are +concerned, because here the cessation of selection is probably +always associated more or less with the reversal of it; and it +is as impossible as it is immaterial to determine the relative +shares which these two co-operating principles take in +bringing about the observed results. But where organisms +in a state of domestication are concerned, the importance of +the question before us is very great. For if the cessation of +selection alone is capable of reducing an organ through +10 or 12 per cent. of its original size, nearly all the direct +evidence on which Darwin relied in favour of use-inheritance +is destroyed. On the other hand, if reduction through 5 per +cent. be deemed a "very liberal estimate" of what this +principle can accomplish, the whole body of Darwin's direct +evidence remains as he left it. I have now given my reasons +for rejecting this lower estimate on the one band, and what +seems to me the extravagant estimate of Weismann on the +other. But my own intermediate estimate is enough to +destroy the apparent proof of use-inheritance that was given +by Darwin. Therefore it remains for those who deny +Lamarckian principles, either to accept some such estimate, +or else to acknowledge the incompatibility of any lower one +with the opinion that there is no evidence in favour of these +principles.</p> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_307" id="Page_307">[Pg 307]</a></p> + + + + +<h2>APPENDIX II.<br /> +<span class="smcap">On Characters as Adaptive and Specific.</span></h2> + + +<p>It is the object of this Appendix to state, more fully than +in the text, the opinions with regard to this subject which +have been published by the two highest authorities on the +theory of natural selection—Darwin and Professor Huxley. +I will take first the opinion of Professor Huxley, quoted <i>in +extenso</i>, and then consider it somewhat more carefully than +seemed necessary in the text.</p> + +<p>As far as I am aware, the only occasion on which +Professor Huxley has alluded to the subject in question, is in +his obituary notice of Darwin in the <i>Proceedings of the Royal +Society</i>, Vol. XLIV, No. 269, p. xviii. The allusion is to my +paper on <i>Physiological Selection</i>, in the <i>Journal of the +Linnæan Society</i>, Zool. Vol. XIX, pp. 337-411. But it will be +observed that the criticism has no reference to the theory +which it is the object of that paper to set forth. It refers +only to my definition of the theory of natural selection as +primarily a theory of the origin, or cumulative development, +of adaptations. This criticism, together with my answer +thereto at the time, is conveyed in the following words.</p> + +<blockquote><p>"Every variety which is selected into a species is favoured +and preserved in consequence of being, in some one or more +respects, better adapted to its surroundings than its rivals. +In other words, every species which exists, exists in virtue +of adaptation, and whatever accounts for that adaptation accounts +for the existence of the species. To say that Darwin<span class="pagenum"><a name="Page_308" id="Page_308">[Pg 308]</a></span> +has put forward a theory of the adaptation of species, but not of +their origin, is therefore to misunderstand the first principles +of the theory. For, as has been pointed out, it is a necessary +consequence of the theory of selection that every species +must have some one or more structural or functional peculiarities, +in virtue of the advantage conferred by which it has +fought through the crowd of its competitors, and achieved a +certain duration. In this sense, it is true that every species +has been 'originated' by selection."</p> + +<p>Now, in the first place, I have nowhere said that "Darwin +has put forward a theory of the adaptation of species, but not +of their origin." I said, and continue to say, that he has +put forward a theory of <i>adaptations in general</i>, and that +where such adaptations appertain to species only (i.e. are +peculiar to particular species), the theory becomes "<i>also</i> a +theory of the origin of the species which present them." The +only possible misunderstanding, therefore, which can here be +alleged against me is, that I fail to perceive it as a "necessary +consequence of the theory of selection that <i>every</i> species <i>must</i> +have some one or more structural or functional <i>peculiarities</i>" +of an adaptive or utilitarian kind. Now, if this is a misunderstanding, +I must confess to not having had it removed by +Mr. Huxley's exposition.</p> + +<p>The whole criticism is tersely conveyed in the form of two +sequent propositions—namely, "Every species which exists, +exists in virtue of adaptation; and whatever accounts for that +adaptation accounts for the existence of the species." My +answer is likewise two-fold. First, I do not accept the premiss; +and next, even if I did, I can show that the resulting conclusion +would not overturn my definition. Let us consider +these two points separately, beginning with the latter, as the +one which may be most briefly disposed of.</p> + +<p>I. Provisionally conceding that "every species which exists, +exists in virtue of adaptation," I maintain that my definition +of the theory of natural selection still holds good. For even +on the basis of this concession, or on the ground of this +assumption, the theory of natural selection is not shown to be +"<i>primarily</i>" a theory of the origin of species. It follows, indeed, +from the assumption—is, in fact, part and parcel of the assumption—that<span class="pagenum"><a name="Page_309" id="Page_309">[Pg 309]</a></span> +all species have been originated by natural +selection; but why? <i>Only because natural selection has originated +those particular adaptive features in virtue of which (by the +hypothesis) species exist as species.</i> It is only in virtue of having +created these features that natural selection has created the +species presenting them—just as it has created genera, families, +orders, &c., in virtue of <i>other</i> adaptive features extending through +progressively wider areas of taxonomic division. Everywhere +and equally this principle has been "primarily" engaged in the +evolution of adaptations, and if one result of its work has +been that of enabling the systematist to trace lines of genetic +descent under his divisions of species, genera, and the rest, +such a result is but "secondary" or "incidental."</p> + +<p>In short, it is "<i>primarily</i>" a theory of adaptations <i>wherever +these occur</i>, and only becomes "<i>also</i>" or "<i>incidentally</i>" +a theory of species in cases where adaptations happen to be +restricted in their occurrence to organic types of a certain order +of taxonomic division.</p> + +<p>II. Hitherto, for the sake of argument, I have conceded +that, in the words of my critic, "it is a necessary consequence +of the theory of selection that every species must have some +one or more structural or functional peculiarities" of an +adaptive kind. But now I will endeavour to show that this +statement does not "follow as a necessary consequence" +from "the theory of selection."</p> + +<p>Most obviously "it follows" from the theory of selection that +"every variety which is selected into a species is favoured and +preserved in consequence of being, in some one or more +respects, better adapted to its surroundings than its rivals." +This, in fact, is no more than a re-statement of the theory +itself. But it does <i>not</i> follow that "every species which exists, +exists in virtue of adaptation" <i>peculiar to that species</i>; i.e. +that every species which exists, exists <i>in virtue of having +been "selected</i>." This may or may not be true as a matter +of fact: as a matter of logic, the inference is not deducible +from the selection theory. Every variety which is "<i>selected +into</i>" a species must, indeed, present some such peculiar +advantage; but this is by no means equivalent to saying, "in +other words," that every variety which <i>becomes</i> a species<span class="pagenum"><a name="Page_310" id="Page_310">[Pg 310]</a></span> +must do so. For the latter statement imports a completely +new assumption—namely, that every variety which <i>becomes</i> +a species must do so because it has been "<i>selected into</i>" a +species. In short, what we are here told is, that if we believe +the selection principle to have given origin to some species, +we must further believe, "as a necessary consequence," that +it has given origin to all species.</p></blockquote> + +<p>The above reply, which is here quoted <i>verbatim</i> from +<i>Nature</i>, Vol. 38, p. 616-18, proceeded to show that it does +not belong to "the first principles of the theory of natural +selection" to deny that no other cause than natural selection +can possibly be concerned in the origin of species; and facts +were given to prove that such unquestionably has been +the case as regards the origin of "local" or "permanent" +<i>varieties</i>. Yet such varieties are what Darwin correctly +terms "incipient" species, or species in process of taking +<i>origin</i>. Therefore, if Professor Huxley's criticism is to stand +at all, we must accept it "as a necessary consequence of the +theory of selection," that every such <i>variety</i> "which exists, +exists in virtue of adaptation"—a statement which is <i>proved</i> +to be untrue by the particular cases forthwith cited. But as +this point has been dealt with much more fully in the text of the +present treatise, I shall sum up the main points in a few words.</p> + +<p>The criticism is all embodied in two propositions—namely, +(<i>a</i>) that the theory of natural selection carries with it, as +a "necessary consequence," the doctrine that survival of the +fittest has been the cause of the origin of <i>all</i> species; and +(<i>b</i>) that therefore it amounts to one and the same thing +whether we define the theory as a theory of species or as +a theory of adaptations. Now, as a mere matter of logical +statement, it appears to me that both these propositions are +unsound. As regards the first, if we hold with Darwin that +other causes have co-operated with natural selection in the +origination of some (i. e. many) species, it is clearly no part +of the theory of natural selection to assume that none of<span class="pagenum"><a name="Page_311" id="Page_311">[Pg 311]</a></span> +these causes can ever have acted independently. In point +of fact, as we have seen in the foregoing chapters, such has +probably and frequently been the case under the influences +of isolation, climate, food, sexual selection, and laws of +growth; but I may here adduce some further remarks with +regard to yet another possible cause. If the Lamarckian +principles are valid at all, no reason can be shown why in +some cases they may not have been competent <i>of themselves</i> +to induce morphological changes of type by successive +increments, until a transmutation of species is effected by +their action alone—as, indeed, Weismann believes to have +been the case with all the species of Protozoa<a name="FNanchor_148_148" id="FNanchor_148_148"></a><a href="#Footnote_148_148" class="fnanchor">[148]</a>. That such +actually has often been the case also with numberless species +of Metozoa, is the belief of the neo-Lamarckians; and +whether they are right or wrong in holding this belief, it is +equally certain that, <i>as a matter of logical reasoning</i>, they are +not compelled by it to profess any <i>disbelief</i> in the agency of +natural selection. They may be mistaken as to the facts, as +Darwin in a lesser degree may have been similarly mistaken; +but just as Darwin has nowhere committed himself to the +statement that <i>all</i> species must <i>necessarily</i> have been originated +by natural selection, so these neo-Lamarckians are perfectly +logical in holding that <i>some</i> species may have been wholly +caused by the inheritance of acquired characters, as <i>other</i> +species may have been wholly caused by the natural selection +of congenital characters. In short, unless we begin by +assuming (with Wallace and against Darwin) that there +<i>can be no other cause</i> of the origin of species than that which +is furnished by natural selection, we have no basis for +Professor Huxley's statement "that every species has been +originated by selection"; while, if we do set out with this +assumption, we end in a mere tautology. What ought to +be done is to prove the validity of this assumption; but, as<span class="pagenum"><a name="Page_312" id="Page_312">[Pg 312]</a></span> +Professor Huxley makes no attempt to do this, his criticism +amounts to mere begging of the question.</p> + +<p>And now, as regards the second point (<i>b</i>), even if we grant +the assumption that natural selection is the only possible +cause of the origin of species—or, which is the same thing, +that every species has been originated by natural selection,—is +it likewise the same thing whether we define the theory of +natural selection as a theory of species or as a theory of +adaptations? Professor Huxley's criticism endeavours to show +that it is; but a little consideration is enough to show that it +is not. What does follow from the assumption is, that, <i>so far +as specific characters are concerned</i>, it is one and the same thing +to say that the theory is a theory of species, and to say that +it is a theory of adaptations. But specific characters are not +conterminous with adaptive characters; for innumerable +adaptive characters are not distinctive of species, but of +genera, families, orders, classes, and sub-kingdoms. Therefore, +if it is believed (as, of course, Professor Huxley +believes) that the theory in question explains the evolution +of all adaptive characters, obviously it is not one and the +same thing to define it indifferently as a theory of species or +as a theory of adaptations.</p> + +<p>Now, all this is not merely a matter of logic chopping. On +the contrary, the question whether we are to accept or to +reject the deduction that all species must necessarily have +owed their origin to natural selection, is a question of no +small importance to the general theory of evolution. And +our answer to this question must be determined by that +which we give to the ulterior question—Is the theory of +natural selection to be defined as a theory of species, or +as a theory of adaptations?</p> + +<hr class="tb" /> + +<p>We now pass on to our consideration of Darwin's opinion +touching the question, as stated by himself,—"The doctrine +of utility, how far true?" As I cannot ascertain that Darwin<span class="pagenum"><a name="Page_313" id="Page_313">[Pg 313]</a></span> +has anywhere expressed an opinion as to whether natural +selection has been necessarily concerned in the origin of all +<i>species</i>, the issue here is as to whether he held this with +regard to all <i>specific characters</i>. It will be remembered that +while opposing this doctrine as erroneous both in logic and +in fact, I have represented that it is not a doctrine which +Darwin sanctioned; but, on the contrary, that it is one +which he expressly failed to sanction, by recognizing the +frequent inutility of specific characters. Mr. Wallace, on the +other hand, alleges that Darwin did believe in the universal—as +distinguished from the general—utility of such characters. +And he adds that he has "looked in vain in Mr. Darwin's +works" for any justification of my statements to the contrary<a name="FNanchor_149_149" id="FNanchor_149_149"></a><a href="#Footnote_149_149" class="fnanchor">[149]</a>. +Therefore I will endeavour to show that Mr. Wallace's search +has not been a very careful one.</p> + +<p>We must remember, however, that it was not until the +appearance of my paper on <i>Physiological Selection</i>, four +years after Darwin's death, that the question now in debate +was raised. Consequently, he never had occasion to deal +expressly with this particular question—viz. whether "the +doctrine of utility" has any <i>peculiar</i> reference to <i>specific</i> +characters—as he surely would have done had he entertained +the important distinction between specific and all other +characters which Mr. Wallace now alleges that he did +entertain. But, be this as it may, we cannot expect +to find in Darwin's writings any express allusion to a +question which had not been raised until 1886. The +most we can expect to find are scattered sentences which +prove that the distinction in question was never so much +as present to his mind,—i. e. never occurred to him as +even a possible distinction.</p><p><span class="pagenum"><a name="Page_314" id="Page_314">[Pg 314]</a></span></p> + +<p>I will first take the passages which Mr. Wallace himself +supplies from among those which I had previously +indicated.</p> + +<blockquote><p>"But when, from the nature of the organism and of the +conditions, modifications have been induced which are unimportant +for the welfare of the <i>species</i>, they may be, and apparently +often have been, transmitted in nearly the same state +to numerous, otherwise modified, descendants<a name="FNanchor_150_150" id="FNanchor_150_150"></a><a href="#Footnote_150_150" class="fnanchor">[150]</a>."</p></blockquote> + +<p>On this passage Mr. Wallace remarks that the last five +words "clearly show that such characters are usually not +'specific,' in the sense that they are such as distinguish +species from one another, but are found in numerous allied +species." But I cannot see that the passage shows anything +of the sort. What to my mind it does show is, (<i>a</i>) that +Mr. Darwin repudiated Mr. Wallace's doctrine touching the +<i>necessary</i> utility of <i>all</i> specific characters: (<i>b</i>) that he takes +for granted the contrary doctrine touching the inutility of +<i>some</i> specific characters: (<i>c</i>) that without in this place +alluding to the proportional number of useless specific +characters, he refers their origin in some cases to "the +nature of the organism" (i.e. "spontaneous variability" due +to internal causes), and in other cases to "the conditions" +(i.e. variability induced by external causes): (<i>d</i>) that when +established as a specific character by heredity, such a useless +character was held by him not to tend to become obsolete by +the influence of natural selection or any other cause; but, on +the contrary, to be "transmitted in nearly the same state to +numerous, otherwise modified, descendants"—or progeny of +the species in genera, families, &c.: (<i>e</i>) and, therefore, that +useless characters which are now distinctive of genera, +families, &c., were held by him frequently, if not usually, to +point to uselessness of origin, when first they arose as merely +specific characters. Even the meaning which Mr. Wallace +reads into this passage must imply every one of these points;<span class="pagenum"><a name="Page_315" id="Page_315">[Pg 315]</a></span> +and therefore I do not see that he gains much by apparently +seeking to add this further meaning—viz. that in Darwin's +opinion there must have been some unassignable reason +preventing the occurrence of useless specific characters in +cases where species are <i>not</i> destined to become the parents +of genera.</p> + +<p>Moreover, any such meaning is out of accordance with +the context from which the passage is taken. For, after +a long consideration of the question of utility, Darwin sums +up,—"We thus see that with plants many morphological +changes may be attributed to the laws of growth and the +interaction of parts, <i>independently of natural selection</i>." And +then he adds,—"From the fact of the above characters being +<i>unimportant for the welfare of the species</i>, any slight variations +which occurred in them <i>would not have been augmented +through natural selection</i>." Again, still within the same +passage, he says, while alluding to the causes other than +natural selection which lead to changes of specific characters,—"If +the <i>unknown cause</i> were to act almost uniformly for +a length of time, we may infer that the result would be +almost uniform; and in this case <i>all</i> the individuals of the +<i>species</i> would be modified in the same manner." For my +own part I do not understand how Mr. Wallace can have +overlooked these various references to <i>species</i>, all of which +occur on the very page from which he is quoting. The +whole argument is to show that "many morphological +changes may be attributed to the laws of growth and the +inter-action of parts [<i>plus</i> external conditions of life], +independently of natural selection"; that such non-adaptive +changes, when they occur as "specific characters," may, if +the species should afterwards give rise to genera, families, +&c., become distinctive of these higher divisions. But there +is nothing here, or in any other part of Darwin's writings, +to countenance the inconsistent notion which Mr. Wallace +appears to entertain,—viz. that species which present useless<span class="pagenum"><a name="Page_316" id="Page_316">[Pg 316]</a></span> +characters are more apt to give rise to genera, families, &c., +than are species which do not present such characters.</p> + +<p>The next passage which Mr. Wallace quotes, with his +comments thereon, is as follows. The italics are his.</p> + +<blockquote><p>"'Thus a large yet undefined extension may safely be given +to the direct and indirect results of natural selection; but I +now admit, after reading the essay of Nägeli on plants, and +the remarks by various authors with respect to animals, more +especially those recently made by Professor Broca, that in +the earlier editions of my Origin of Species I perhaps attributed +too much to the action of natural selection, or the survival +of the fittest. I have altered the fifth edition of the +Origin so as to confine my remarks to adaptive changes of +structure; <i>but I am convinced, from the light gained during +even the last few years, that very many structures which now +appear to be useless, will hereafter be proved to be useful, +and will therefore come within the range of natural selection</i>. +Nevertheless I did not formerly consider sufficiently the existence +of structures which, as far as we can at present judge, +are neither beneficial nor injurious; and this I believe to be +one of the greatest oversights as yet detected in my work.'</p> + +<p>Now it is to be remarked that neither in these passages +nor in any of the other less distinct expressions of opinion on +this question, does Darwin ever admit that "specific characters"—that +is, the particular characters which serve to distinguish +one species from another—are ever useless, much less that +"a large proportion of them" are so, as Mr. Romanes makes +him "freely acknowledge." On the other hand, in the passage +which I have italicised he strongly expresses his view that +much of what we suppose to be useless is due to our ignorance; +and as I hold myself that, as regards many of the supposed +useless characters, this is the true explanation, it may +be well to give a brief sketch of the progress of knowledge +in transferring characters from the one category to the other<a name="FNanchor_151_151" id="FNanchor_151_151"></a><a href="#Footnote_151_151" class="fnanchor">[151]</a>."</p></blockquote> + +<p>It is needless to continue this quotation, because of course +no one is disputing that an enormous number of specific<span class="pagenum"><a name="Page_317" id="Page_317">[Pg 317]</a></span> +characters whose utility is unknown are nevertheless useful, +and therefore due to natural selection. In other words, +the question is not—Are there not many useful specific +characters whose utility is unknown? but—Does it follow +from the theory of natural selection that all specific +characters must necessarily be useful? Well, it appears to +me that without going further than the above passage, +which Mr. Wallace has quoted, we can see clearly enough +what was Darwin's opinion upon the subject. He did not +believe that it followed <i>deductively</i> from his theory that all +specific characters must necessarily be useful; and therefore +he regarded it as a question of <i>fact</i>—to be determined +by induction as distinguished from deduction—in what +proportional number of cases they are so. Moreover he +gives it as his more matured opinion, that, "as far as we can +at present judge" (i.e. from the present state of observation +upon the subject: if, with Mr. Wallace, his judgement were +<i>a priori</i>, why this qualification?), he had not previously +sufficiently considered the existence of non-adaptive characters—and +this he ended by believing was one of the greatest +oversights as yet detected in his work. To me it has always +seemed that this passage is one of the greatest exhibitions of +candour, combined with solidity of judgement, that is to be +met with even in the writings of Darwin. There is no talk +about any deductive "necessity"; but a perfect readiness to +allow that causes other than natural selection may have been +at work in evoking non-adaptive characters, so that the fifth +edition of the <i>Origin of Species</i> was altered in order to +confine the theory of natural selection to "adaptive changes"—i.e. +to constitute it, as I have said in other words, +"a theory of the origin, or cumulative development, of +<i>adaptations</i>."</p> + +<p>If to this it be said that in the above passage there +is no special mention of <i>species</i>, the quibble would admit +of a <span class="correction" title="Transcriber's Note: 'threefold' in the text.">three-fold</span> reply. In the first place, the quibble in<span class="pagenum"><a name="Page_318" id="Page_318">[Pg 318]</a></span> +question had never been raised. As already stated, it is +only since the appearance of my own paper on <i>Physiological +Selection</i> that anybody ever thought of drawing a distinction +between species and genera, such that while all specific characters +must be held necessarily useful, no such necessity extends +to generic characters. In the second place, that Darwin must +have had specific characters (as well as generic) in his mind +when writing the above passage, is rendered unquestionable +by the fact that many of the instances of inutility adduced by +Nägeli and Broca have reference to specific characters. +Lastly, as shown in the passages previously quoted from the +sixth edition of the <i>Origin of Species</i>, Darwin attributed the +origin of useless generic characters to useless specific +characters; so that Mr. Wallace really gains nothing by his +remark that specific characters are not specially mentioned +in the present passage.</p> + +<p>Once more:—</p> + +<blockquote><p>"Darwin's latest expression of opinion on this question is +interesting, since it shows he was inclined to return to his +earlier view of the general, or universal, utility of specific +characters<a name="FNanchor_152_152" id="FNanchor_152_152"></a><a href="#Footnote_152_152" class="fnanchor">[152]</a>."</p></blockquote> + +<p>This "latest expression of opinion," as I shall immediately +prove, shows nothing of the kind—being, in fact, a mere +re-statement of the opinion everywhere and at all times +expressed by Darwin, touching the caution that must be +observed in deciding, <i>with respect to individual cases</i>, whether +an apparently useless specific character is to be regarded as +really useless. Moreover, at no time and in no place did +Darwin entertain any "view of the general, or universal, +utility of specific characters." But the point now is, that if +(as was the case) Darwin "inclined" to depart more and +more from his earlier view of the highly <i>general</i> utility of +specific characters; and if (as was not the case) he ended by +showing an inclination "<i>to return</i>" to this earlier view; what<span class="pagenum"><a name="Page_319" id="Page_319">[Pg 319]</a></span> +becomes of the whole of Mr. Wallace's contention against +which this Appendix is directed, namely, <i>that Darwin never +entertained any other view than that of the "general, or +universal, utility of specific characters</i>"?</p> + +<p>The "latest expression of opinion" which Mr. Wallace +quotes, occurs in a letter written to Professor Semper in +1878. It is as follows:—</p> + +<blockquote><p>"As our knowledge advances, very slight differences, considered +by systematists as of no importance in structure, are +continually found to be functionally important; and I have +been especially struck with this fact in the case of plants, to +which my observations have of late years been confined. Therefore +it seems to me rather rash to consider the slight differences +between representative species, for instance those inhabiting +the different islands of the same archipelago, as of +no functional importance, and as not in any way due to natural +selection<a name="FNanchor_153_153" id="FNanchor_153_153"></a><a href="#Footnote_153_153" class="fnanchor">[153]</a>."</p></blockquote> + +<p>Now, with regard to this passage it is to be observed, as +already remarked, that it refers to the formation of final +judgements touching <i>particular cases</i>: there is nothing to show +that the writer is contemplating <i>general principles</i>, or advocating +on deductive grounds the dogma that specific characters +must be necessarily and universally adaptive characters. +Therefore, what he here says is neither more nor less than +I have said. For I have always held that it would be "rather +rash" to conclude that any given cases of apparent inutility +are certainly cases of real inutility, <i>merely on the ground that +utility is not perceived</i>. But this is clearly quite a distinct +matter from resisting the <i>a priori</i> generalization that all cases +of apparent inutility must certainly be cases of real utility. +And, I maintain, in every part of his writings, without any +exception, where Darwin alludes to this matter of general +principle, it is in terms which directly contradict the deduction +in question. As the whole of this Appendix has<span class="pagenum"><a name="Page_320" id="Page_320">[Pg 320]</a></span> +been directed to proving that such is the case, it will now, +I think, be sufficient to supply but one further quotation, in +order to show that the above "latest expression of opinion," +far from indicating that in his later years Darwin "inclined" +to Mr. Wallace's views upon this matter, is quite compatible +with a distinct "expression of opinion" to the contrary, in +a letter written less than six years before his death.</p> + +<blockquote><p>"In my opinion <i>the greatest error which I have committed</i>, +has been not allowing sufficient weight to the direct action of +the environment, i.e. food, climate, &c., <i>independently of natural +selection</i>. Modifications thus caused, <i>which are neither of +advantage nor disadvantage to the modified organisms</i>, would +be especially favoured, as I can now see chiefly through +your observations, <i>by isolation in a small area, where only +a few individuals lived under nearly uniform conditions</i><a name="FNanchor_154_154" id="FNanchor_154_154"></a><a href="#Footnote_154_154" class="fnanchor">[154]</a>."</p></blockquote> + +<p>I will now proceed to quote further passages from +Darwin's works, which appear to have escaped the notice of +Mr. Wallace, inasmuch as they admit of no doubt regarding +the allusions being to <i>specific</i> characters.</p> + +<blockquote><p>"<i>We may easily err in attributing importance to characters, +and in believing that they have been developed through natural +selection.</i> We must by no means overlook the effects of the +definite action of changed conditions of life,—of so-called +spontaneous variations, which seem to depend in a quite +subordinate degree on the nature of the conditions,—of the +tendency to reversion to long-lost characters,—of the complex +laws of growth, such as of correlation<a name="FNanchor_155_155" id="FNanchor_155_155"></a><a href="#Footnote_155_155" class="fnanchor">[155]</a>, compensation, of +pressure of one part on another, &c., and finally of sexual +selection, by which characters of use to one sex are often +gained and then transmitted more or less perfectly to the<span class="pagenum"><a name="Page_321" id="Page_321">[Pg 321]</a></span> +other sex, though of no use to this sex. But structures thus +indirectly gained, <i>although at first of no advantage to a species</i>, +may subsequently have been taken advantage of by its modified +descendants, under new conditions of life and newly acquired +habits<a name="FNanchor_156_156" id="FNanchor_156_156"></a><a href="#Footnote_156_156" class="fnanchor">[156]</a>."</p></blockquote> + +<p>It appeared—and still appears—to me, that where so many +causes are expressly assigned as producing useless <i>specific</i> +characters, and that some of them (such as climatic influences +and independent variability) must be highly general in their +action, I was justified in representing it as Darwin's opinion +that "a large proportional number of specific characters" +are useless to the <i>species</i> presenting them, although afterwards +they may sometimes become of use to genera, families, +&c. Moreover, this passage goes on to point out that +specific characters which at first sight appear to be obviously +useful, are sometimes found by fuller knowledge to be really +useless—a consideration which is the exact inverse of the +argument from ignorance as used by Mr. Wallace, and +serves still further to show that in Darwin's opinion utility is +by no means an invariable, still less a "necessary," mark of +specific character. The following are some of the instances +which he gives.</p> + +<blockquote><p>"The sutures in the skulls of young mammals have been advanced +as a beautiful adaptation for aiding parturition, and no +doubt they may facilitate, or be indispensable for this act; +but as sutures occur in the skulls of young birds and reptiles, +which have only to escape from a broken egg, we may infer +that this structure has <i>arisen from the laws of growth</i>, and +has been taken advantage of in the parturition of the higher +animals<a name="FNanchor_157_157" id="FNanchor_157_157"></a><a href="#Footnote_157_157" class="fnanchor">[157]</a>."</p> + +<p>"The naked skin on the head of a vulture is generally considered +as a direct adaptation for wallowing in putridity; +and so it may be, <i>or it may possibly be due to the direct +action of the putrid matter</i>; but we should be very cautious<span class="pagenum"><a name="Page_322" id="Page_322">[Pg 322]</a></span> +in drawing any such inference [i.e. as to utility] when we see +the skin on the head of the clean-feeding male Turkey is +likewise naked<a name="FNanchor_158_158" id="FNanchor_158_158"></a><a href="#Footnote_158_158" class="fnanchor">[158]</a>."</p></blockquote> + +<p>Similarly, in the <i>Descent of Man</i> it is said:—</p> + +<blockquote><p>"Variations of the same <i>general</i> nature have <i>often been taken +advantage of</i> and accumulated through sexual selection in relation +to the propagation of the species, and through natural +selection in relation to the general purposes of life. Hence, +<i>secondary sexual characters, when equally transmitted to both +sexes, can be distinguished from ordinary specific characters, +only by the light of analogy</i>. The modifications acquired +through sexual selection are often so strongly pronounced +that the two sexes have frequently been ranked as distinct +species, or even as distinct genera<a name="FNanchor_159_159" id="FNanchor_159_159"></a><a href="#Footnote_159_159" class="fnanchor">[159]</a>."</p></blockquote> + +<p>As Mr. Wallace does not recognize sexual selection, he +incurs the burden of proving utility (in the life-preserving +sense) in all these "frequently" occurring cases where there +are such "strongly pronounced modifications," and we have +already seen in the text his manner of dealing with this +burden. But the point here is, that whether or not we +accept the theory of sexual selection, we must accept +it as Darwin's opinion—first, that in their beginnings, as +<i>specific</i> characters, these sexual modifications were often +of a merely "<i>general nature</i>" (or without reference to +utility even in the life-embellishing sense), and only <i>afterwards</i> +"have often been taken advantage of and accumulated +through <i>sexual</i> selection": and, secondly, that "we +know they have been acquired in some instances <i>at the +cost not only of inconvenience, but of exposure to actual +dangers</i><a name="FNanchor_160_160" id="FNanchor_160_160"></a><a href="#Footnote_160_160" class="fnanchor">[160]</a>."</p> + +<p>We may now pass on to some further, and even stronger, +expressions of opinion with regard to the frequent inutility of +<i>specific</i> characters.</p><p><span class="pagenum"><a name="Page_323" id="Page_323">[Pg 323]</a></span></p> + +<blockquote><p>"I have made these remarks only to show that, if we are unable +to account for the characteristic differences of our several +domestic breeds, which nevertheless are generally admitted to +have arisen through ordinary generation from one or a few +parent stocks, we ought not to lay too much stress on our +ignorance of the precise cause [i.e. whether natural selection +or some other cause] of the slight analogous differences between +true <i>species</i>.... I fully admit that <i>many</i> structures are now +of no use to their possessors, and may never have been of +any use to their progenitors; but this does not prove that +they were formed solely for beauty or variety. No doubt the +definite action of changed conditions, and the various causes +of modification, lately specified, have all produced an effect, +<i>probably a great effect, independently of any advantage thus +gained</i>.... It is scarcely possible to decide how much +allowance ought to be made for such causes of change, as +the definite action of external conditions, so-called spontaneous +variations, and the complex laws of growth; but, <i>with these +important exceptions</i>, we may conclude that the structure of +every living creature either now is, or formerly was, of some +direct or indirect use to its possessor<a name="FNanchor_161_161" id="FNanchor_161_161"></a><a href="#Footnote_161_161" class="fnanchor">[161]</a>."</p></blockquote> + +<p>Here again, if we remember how "important" these +"exceptions" are, I cannot understand any one doubting +Darwin's opinion to have been that a large proportional +number of specific characters are useless. For that it is +"species" which he here has mainly in his mind is evident +from what he says when again alluding to the subject in +his "Summary of the Chapter"—namely, "In <i>many</i> other +cases [i.e. in cases where natural selection has not been +concerned] modifications are probably the direct result of +the laws of variation or of growth, independently of any +good having been thus gained." Now, not only do these +"laws" apply as much to species as they do to genera; +"but," the passage goes on to say, "even such structures +have often, we may feel assured, been subsequently taken<span class="pagenum"><a name="Page_324" id="Page_324">[Pg 324]</a></span> +advantage of, and still further modified, for the good of +<i>species</i> under new conditions of life." Obviously, therefore, +the inutility in such cases is taken to have been prior +to any utility subsequently acquired; and genera are not +historically prior to the species in which they originate.</p> + +<p>Here is another quotation:—</p> + +<blockquote><p>"Thus, as I am inclined to believe, morphological differences, +which we consider as important—such as the arrangement of +the leaves, the divisions of the flower or of the ovarium, the +position of the ovules, &c.—<i>first</i> appeared in <i>many</i> cases as +<i>fluctuating variations</i>, which sooner or later became constant +through the nature of the organism and of the surrounding +conditions, as well as through the intercrossing of distinct individuals, +<i>but not through natural selection</i>; for as these +morphological characters do not affect the welfare of the +<i>species</i>, any slight deviations in them could not have been +governed or accumulated through this latter agency. It is a +strange result which we thus arrive at, namely, that characters +of slight vital importance to the <i>species</i>, are the most important +to the systematist; but, as we shall hereafter see when +we treat of the genetic principle of classification, this is by +no means so paradoxical as it may at first appear<a name="FNanchor_162_162" id="FNanchor_162_162"></a><a href="#Footnote_162_162" class="fnanchor">[162]</a>."</p></blockquote> + +<p>Clearly the view here expressed is that characters which +are now distinctive of higher taxonomic divisions "first +appeared" in the parent species of such divisions; for +not only would it be unreasonable to attribute the rise and +preservation of useless characters to "fluctuating variations" +affecting a number of species or genera similarly and simultaneously; +but it would be impossible that, if such were the +case, they could be rendered "constant through the nature +of the organism and of the surrounding conditions, as well as +through the intercrossing of distinct individuals<a name="FNanchor_163_163" id="FNanchor_163_163"></a><a href="#Footnote_163_163" class="fnanchor">[163]</a>."</p> +<p><span class="pagenum"><a name="Page_325" id="Page_325">[Pg 325]</a></span></p> +<p>Here is another passage to the same general effect. In +alluding to the objection from inutility as advanced by +Bronn, Broca, and Nägeli, Mr. Darwin says:—"There is +much force in the above objection"; and, after again +pointing out the important possibility in any particular +cases of hidden or former use, and the action of the laws of +growth, he goes on to say,—"In the third place, we have +to allow for the direct and definite action of changed conditions +of life, and for so-called spontaneous variations, in +which the nature of the conditions plays quite a subordinate +part<a name="FNanchor_164_164" id="FNanchor_164_164"></a><a href="#Footnote_164_164" class="fnanchor">[164]</a>." Elsewhere he says,—"It appears that I +formerly underrated the frequency and value of these latter +forms of variation as leading to permanent modifications of +structure <i>independently of natural selection</i><a name="FNanchor_165_165" id="FNanchor_165_165"></a><a href="#Footnote_165_165" class="fnanchor">[165]</a>." The "forms of +variation" to which he here alludes are "variations which +seem to us in our ignorance to arise spontaneously"; and +it is evident that such variations cannot well "arise" in +two or more species of a genus similarly and simultaneously, +so as independently to lead "to permanent modifications +of structure" in two or more parallel lines. It is +further evident that by "spontaneous variations" Darwin +alludes to extreme cases of spontaneous departure from +the general average of specific characters; and therefore +that lesser or more ordinary departures must be of still +greater "frequency."</p> + +<p>Again, speaking of the principles of classification, +Darwin writes:—</p> + +<blockquote><p>"We care not how trifling a character may be—let it be the +mere inflection of the angle of the jaw, the manner in which<span class="pagenum"><a name="Page_326" id="Page_326">[Pg 326]</a></span> +an insect's wing is folded, whether the skin be covered by +hair or feathers—if it prevail throughout many and different +species, especially those having very different habits of life, +it assumes high value [i.e. for purposes of classification]; for +we can account for its presence in so many forms with such +<i>different habits</i>, only by inheritance from a common parent. +We may err in this respect in regard to single points of structure, +but when several characters, let them be ever so trifling, concur +throughout a large group of beings <i>having different habits</i>, we +may feel almost sure, on the theory of descent, that these +characters have been inherited from a common ancestor; and +we know that such aggregated characters have especial value +in classification<a name="FNanchor_166_166" id="FNanchor_166_166"></a><a href="#Footnote_166_166" class="fnanchor">[166]</a>."</p></blockquote> + +<p>Now it is evident that this argument for the general +theory of evolution would be destroyed, if Wallace's assumption +of utility of specific characters as universal were +to be entertained. And the fact of apparently "trifling" +characters occurring throughout a large group of beings +"having different habits" is proof that they are really trifling, +or without utilitarian significance.</p> + +<p>It is needless to multiply these quotations, for it appears +to me that the above are amply sufficient to establish +the only point with which we are here concerned, namely, +that Darwin's opinion on the subject of utility in relation +to specific characters was substantially identical with my +own. And this is established, not merely by the literal +meaning of the sundry passages here gathered together +from different parts of his writings; but likewise, and perhaps +still more, from the tone of thought which pervades +these writings as a whole. It requires no words of mine +to show that the literal meaning of the above quotations +is entirely opposed to Mr. Wallace's view touching the +<i>necessary</i> utility of <i>all</i> specific characters; but upon the +other point—or the general tone of Mr. Darwin's thought +regarding such topics—it may be well to add two remarks.</p><p><span class="pagenum"><a name="Page_327" id="Page_327">[Pg 327]</a></span></p> + +<p>In the first place, it must be evident that so soon as +we cease to be bound by any <i>a priori</i> deduction as to +natural selection being "the exclusive means of modifications," +it ceases to be a matter of much concern to the theory of +natural selection in what proportion other means of modification +have been at work—especially when non-adaptive +modifications are concerned, and where these have reference +to merely "specific characters," or modifications of +the most incipient kind, least generally diffused among +organic types, and representing the incidence of causes of +less importance than any others in the process of organic +evolution considered as a whole. Consequently, in the +second place, we find that Darwin nowhere displays any +solicitude touching the proportional number of specific characters +that may eventually prove to be due to causes other +than natural selection. He takes a much wider and +deeper view of organic evolution, and, having entirely +emancipated himself from the former conception of +species as the organic units, sees virtually no significance +in specific characters, except in so far as they are also +adaptive characters.</p> + +<p>Such, at all events, appears to me the obvious interpretation +of his writings when these are carefully read with a view to +ascertaining his ideas upon "Utilitarian doctrine: how far +true." And I make these remarks because it has been laid +to my charge, that in quoting such passages as the above I +have been putting "a strained interpretation" upon Darwin's +utterances: "such admissions," it is said, "Mr. Romanes +appears to me to treat as if wrung from a hostile witness<a name="FNanchor_167_167" id="FNanchor_167_167"></a><a href="#Footnote_167_167" class="fnanchor">[167]</a>." +But, from what has gone before, it ought to be apparent +that I take precisely the opposite view to that here imputed. +Far from deeming these and similar passages as "admissions +wrung from a hostile witness," and far from seeking<span class="pagenum"><a name="Page_328" id="Page_328">[Pg 328]</a></span> +to put any "strained interpretation" upon them, I believe +that they are but the plain and unequivocal expressions +of an opinion which I have always understood that +Darwin held. And if any one has been led to think otherwise, +I throw back this charge of "strained interpretation," +by challenging such a person to adduce a single quotation +from any part of Darwin's works, which can possibly be +held to indicate that he regarded passages like those +above quoted as in any way out of conformity with his +theory of natural selection—or as put forward merely +to "admit the possibility of explanations, to which really, +however, he did not attach much importance." To the +best of my judgement it is only some bias in favour of +Mr. Wallace's views that can lead a naturalist to view in +this way the clear and consistent expression of Darwin's.</p> + +<p>That Mr. Wallace himself should be biassed in this matter +might, perhaps, be expected. After rendering the following +very unequivocal passage from the <i>Origin of Species</i> (p. 72)—"There +can be little doubt that the tendency to vary in the +same manner has often been so strong, <i>that all individuals of +the same species have been similarly modified without the aid of +any form of selection</i>"—Mr. Wallace says, "But no proof +whatever is offered of this statement, and it is so entirely +opposed to all we know of the facts of variation as given by +Darwin himself, that the important word 'all' is probably an +oversight." But, if Mr. Wallace had read the very next +sentence he would have seen that here the important +word "all" could not <i>possibly</i> have been "an oversight." +For the passage continues,—"Or only a third, fifth, or tenth +part of the individuals may have been thus affected, of which +fact several instances could be given. Thus Graba estimates +that about one-fifth of the guillemots in the Faroe Islands +consist of a variety so well marked, that it was formerly +ranked as a distinct species under the name of Uria +lacrymans." And even if this passage had not been thus<span class="pagenum"><a name="Page_329" id="Page_329">[Pg 329]</a></span> +specially concerned with the question of the <i>proportion</i> in +which "<i>individuals of the same species have been similarly +modified without the aid of any form of selection</i>" the oversight +with respect to "the important word 'all'" would still have +remained an oversight of a recurrent character, as the following +additional quotations from other parts of Darwin's +writings may perhaps render apparent.</p> + +<blockquote><p>"There must be some efficient cause for each slight individual +difference, as well as for more strongly marked variations +which occasionally arise; and if the unknown cause were to +act persistently, it is almost certain that <i>all</i> the individuals +of the <i>species</i> would be similarly modified<a name="FNanchor_168_168" id="FNanchor_168_168"></a><a href="#Footnote_168_168" class="fnanchor">[168]</a>."</p> + +<p>"The acquisition of a useless part can hardly be said to +raise an organism in the natural scale.... We are so ignorant +of the exciting cause of the above specified modifications; +but if the unknown cause were to act almost uniformly for a +length of time, we may infer that the result would be almost +uniform; and in this case <i>all</i> the individuals of the <i>species</i> +would be modified in the same manner<a name="FNanchor_169_169" id="FNanchor_169_169"></a><a href="#Footnote_169_169" class="fnanchor">[169]</a>."</p></blockquote> + +<p>Moreover, when dealing even with such comparatively +slight changes as occur between our domesticated varieties—and +which, <i>a fortiori</i>, are less likely to become "stable" +through the uniform operation of causes other than selection, +seeing that they are not only smaller in amount than +occurs among natural species, but also have had but a +comparatively short time in which to accumulate—Darwin +is emphatic in his assertion of the same principles. For +instance, in the twenty-third chapter of the <i>Variation of +Plants and Animals under Domestication</i>, he repeatedly +uses the term "definite action of external conditions," and +begins the chapter by explaining his use of the term +thus:—</p> + +<blockquote><p>"By the term definite action, as used in this chapter, I mean +an action of such a nature that, when many individuals of<span class="pagenum"><a name="Page_330" id="Page_330">[Pg 330]</a></span> +the same variety are exposed during several generations to +any change in their physical conditions of life, <i>all</i>, or <i>nearly +all</i>, the individuals are modified in the same manner. A new +<i>sub-variety</i> would thus be produced <i>without the aid of selection</i><a name="FNanchor_170_170" id="FNanchor_170_170"></a><a href="#Footnote_170_170" class="fnanchor">[170]</a>."</p></blockquote> + +<p>As an example of the special instances that he gives, +I may quote the following from the same work:—</p> + +<blockquote><p>"Each of the endless variations which we see in the plumage +of our fowls must have had some efficient cause; and if the +same cause were to act uniformly during a long series of +generations on many individuals, <i>all</i> probably would be modified +in the same manner."</p></blockquote> + +<p>And, as instances of his more general statements in Chapter +XXIII, these may suffice:—</p> + +<blockquote><p>"The direct action of the conditions of life, whether leading +to definite or indefinite results, <i>is a totally distinct consideration +from the effects of natural selection</i>.... The +direct and definite action of changed conditions, in contradistinction +to the accumulation of indefinite variations, <i>seems +to me so important</i> that I will give a large additional body +of miscellaneous facts<a name="FNanchor_171_171" id="FNanchor_171_171"></a><a href="#Footnote_171_171" class="fnanchor">[171]</a>."</p></blockquote> + +<p>Then, after giving these facts, and showing how in the +case of species in a state of nature it is often impossible to +decide how much we are to attribute to natural selection and +how much to the definite action of changed conditions, he +begins his general summary of the chapter thus:—</p> + +<blockquote><p>"There can be no doubt, from the facts given in the early +part of this chapter, that extremely slight changes in the +conditions of life sometimes act in a definite manner on our +already variable domesticated productions [productions, therefore, +with regard to which uniformity and 'stability' of +modification are least likely to arise]; and, as the action +Of changed conditions in causing general or indefinite variability<span class="pagenum"><a name="Page_331" id="Page_331">[Pg 331]</a></span> +is accumulative, so it may be with their definite action. +Hence it is possible that <i>great</i> and <i>definite</i> modifications +of structure may result from altered conditions acting during +a long series of generations. In some few instances a marked +effect has been produced quickly on <i>all</i>, or <i>nearly all</i>, the +individuals which have been exposed to some considerable +change of climate, food, or other circumstance<a name="FNanchor_172_172" id="FNanchor_172_172"></a><a href="#Footnote_172_172" class="fnanchor">[172]</a>."</p></blockquote> + +<p>Once more, in order to show that he retained these views +to the end of his life, I may quote a passage from the second +edition of the <i>Descent of Man</i>, which is the latest expression +of his opinion upon these points:—</p> + +<blockquote><p>"Each of the endless diversities in plumage, which we see +in our domesticated birds, is, of course, the result of some definite +cause; and under natural and more uniform conditions, +some one tint, <i>assuming that it was in no way injurious, would +almost certainly sooner or later prevail</i>. The free-intercrossing +of the many individuals belonging to the same species +would ultimately tend to make any change of colour thus induced +<i>uniform in character</i>.... Can we believe that the +very slight differences in tints and markings between, for instance, +the female black-grouse and red-grouse serve as a +protection? Are partridges as they are now coloured, better +protected than if they had resembled quails? Do the slight +differences between the females of the common pheasant, the +Japan and golden pheasants, serve as a protection, or might +not their plumage have been interchanged with impunity? +From what Mr. Wallace has observed of the habits of certain +gallinaceous birds in the East, he thinks that such slight +differences are beneficial. For myself, I will only say, I am +not convinced<a name="FNanchor_173_173" id="FNanchor_173_173"></a><a href="#Footnote_173_173" class="fnanchor">[173]</a>."</p></blockquote> + +<p>Yet "convinced" he certainly must have been on merely +<i>a priori</i> grounds, had he countenanced Mr. Wallace's +reasoning from the general theory of natural selection; and +the fact that he here fails to be convinced even by "what +Mr. Wallace has observed of the habits of certain gallinaceous<span class="pagenum"><a name="Page_332" id="Page_332">[Pg 332]</a></span> +birds," appears to indicate that he had considered the question +of utility with special reference to Mr. Wallace's opinion. +That opinion was then, as now, the avowed result of a theoretical +prepossession; and this prepossession, as the above +quotations sufficiently show, was expressly repudiated by +Darwin.</p> + +<p>Lastly, this is not the only occasion on which Darwin +expressly repudiates Mr. Wallace's opinion on the point +in question. For it is notorious that these co-authors of +the theory of natural selection have expressed divergent +opinions concerning the origin by natural selection of the +most general of all specific characters—cross-sterility. +Although allowing that cross-sterility between allied species +may be of adaptive value in "keeping incipient species from +blending," Darwin persistently refused to be influenced by +Wallace's belief that it is due to natural selection; i.e. the +belief on which alone can be founded the "necessary deduction" +with which we have been throughout concerned.</p><hr class="chap" /><p><span class="pagenum"><a name="Page_333" id="Page_333">[Pg 333]</a></span></p> + + + + +<h2><span class="smcap">Note A to Page 57.</span></h2> + + +<p>I think it is desirable here to adduce one or two concrete +illustrations of these abstract principles, in order to show how, +as a matter of fact, the structure of Weismann's theory is +such as to preclude the possibility of its assumptions being +disproved—and this even supposing that the theory is false.</p> + +<p>At first sight nothing could seem more conclusive on the +side of Darwinian or Lamarckian principles than are the facts +of hereditary disease, in cases where the disease has unquestionably +been acquired by the parents. Take, for example, +the case of gout. Here there is no suspicion of any microbe +being concerned, nor is there any question about the fact +of the disease being one which is frequently acquired by +certain habits of life. Now, suppose the case of a man who +in middle age acquires the gout by these habits of life—such +as insufficient exercise, over-sufficient food, and free indulgence +in wine. His son inherits the gouty diathesis, and even though +the boy may have the fear of gout before his eyes, and consequently +avoid over-eating and alcoholic drinking, &c., the +disease may overtake him also. Well, the natural explanation +of all this is, that the sins of the fathers descend upon the +children; that gout acquired may become in the next generation +gout transmitted. But, on the other hand, the school of +Weismann will maintain that the reason why the parent +contracted the gout was because he had a congenital, or +"blastogenetic," tendency towards that disease—a tendency +which may, indeed, have been intensified by his habits of +life, but which, in so far as thus intensified, was not transmitted +to his offspring. All that was so transmitted was the<span class="pagenum"><a name="Page_334" id="Page_334">[Pg 334]</a></span> +congenital tendency; and all that is proved by such cases as +those above supposed, where the offspring of gouty parents +become gouty notwithstanding their abstemious habits, is that +in such offspring the congenital tendency is even more pronounced +than it was in their parents, and therefore did not +require so much inducement in the way of unguarded living +to bring it out. Now, here again, without waiting to consider +the relative probabilities of these two opposing explanations, +it is enough for the purposes of the illustration to remark +that it is obviously impossible to disprove either by means +of the other, or by any class of facts to which they may +severally appeal.</p> + +<p>I will give only one further example to show the elusiveness +of Weismann's theory, and the consequent impossibility of +finding any cases in nature which will satisfy the conditions +of proof which the theory imposes. In one of his papers +Weismann says that if there be any truth in the Lamarckian +doctrine of the transmission of acquired characters, it ought +to follow that the human infant should speak by instinct. +For, ever since man became human he has presumably been +a talking animal: at any rate it is certain that he has been +so for an innumerable number of generations. Therefore, by +this time the faculty of language ought to have been so +deeply impressed upon the psychology of the species, that +there ought to be no need to teach the young child its use +of language; and the fact that there is such need is taken +by Weismann to constitute good evidence in proof of the +non-transmissibility of individually acquired characters. Or, +to quote his own words, "it has never yet been found that +a child could read of itself, although its parents had throughout +their whole lives practised this art. Not even are our children +able to talk of their own accord; yet not only have their +parents, but, more than that, an infinitely long line of ancestors +have never ceased to drill their brains and to perfect their +organs of speech.... From this alone we may be disposed +to doubt whether acquired capabilities in the true sense can +ever be transmitted." Well, in answer to this particular case, +we have first of all to remark that the construction of even +the simplest language is, psychologically considered, a matter<span class="pagenum"><a name="Page_335" id="Page_335">[Pg 335]</a></span> +of such enormous complexity, that there is no real analogy +between it and the phenomena of instinct: therefore the fact +that Lamarckian principles cannot be applied to the case +of language is no evidence that they do not hold good as +regards instinct. Secondly, not only the construction, but +still more the use of language is quite out of analogy with +all the phenomena of instinct; for, in order to use, or speak, +a language, the mind must already be that of a thinking +agent; and therefore to expect that language should be instinctive +is tantamount to expecting that the thought of which +it is the vehicle should be instinctive—i.e. that human parents +should transmit the whole organization of their own intellectual +experiences to their unborn children. Thirdly, even neglecting +these considerations, we have to remember that language has +been itself the product of an immensely long course of evolution; +so that even if it were reasonable to expect that a child +should speak by instinct without instruction, it would be +necessary further to expect that the child should begin by +speaking in some score or two of unknown tongues before +it arrived at the one which alone its parents could understand. +Probably these considerations are enough to show +how absurd is the suggestion that Darwinians ought to expect +children to speak by instinct. But, now, although it is for +these reasons preposterous under any theory of evolution to +expect that children should be able to use a fully developed +language without instruction, it is by no means so preposterous +to expect that, if all languages present any one simple set +of features in common, these features might by this time +have grown to be instinctive; for these simple features, being +common to all languages, must have been constantly and +forcibly impressed upon the structure of human psychology +throughout an innumerable number of sequent generations. +Now, there is only one set of features common to all languages; +and this comprises the combinations of vowel and consonantal +sounds, which go to constitute what we know as articulate +syllables. And, is it not the case that these particular features, +thus common to all languages, as a matter of fact actually +<i>are</i> instinctive? Long before a young child is able to understand +the meanings of any words, it begins to babble articulate<span class="pagenum"><a name="Page_336" id="Page_336">[Pg 336]</a></span> +syllables; and I do not know that a more striking fact can +be adduced at the present stage of the Weismann controversy +than is this fact which he has thus himself unconsciously +suggested, namely, that the young of the only talking animal +should be alone in presenting—and in unmistakably presenting—the +instinct of articulation. Well, such being the +state of matters as regards this particular case, in the course +of a debate which was held at the Newcastle meeting of the +British Association upon the heredity question, I presented +this case as I present it now. And subsequently I was met, +as I expected to be met, by its being said that after all the +faculty of making articulate sounds might have been of congenital +origin. Seeing of how much importance this faculty +must always have been to the human species, it may very +well have been a faculty which early fell under the sway +of natural selection, and so it may have become congenital. +Now, be it remembered, I am only adducing this case in +illustration of the elusiveness of Weismann's theory. First +of all he selects the faculty of articulate speech to argue that +it is a faculty which ought to be instinctive if acquired characters +ever do become instinctive; and so good does he deem +it as a test case between the two theories, that he says <i>from +it alone</i> we should be prepared to accept the doctrine that +acquired characters can never become congenital. Then, when +it is shown that the only element in articulate speech which +possibly could have become congenital, actually has become +congenital, the answer we receive is a direct contradiction +of the previous argument: the faculty originally selected as +representative of an acquired character is now taken as representative +of a congenital one. By thus playing fast and loose +with whatever facts the followers of Darwin may adduce, the +followers of Weismann bring their own position simply to +this:—All characters which can be shown to be inherited +we assume to be congenital, or as we term it, "blastogenetic," +while all characters which can be shown not to be inherited, +we assume to be acquired, or as we term it, "somatogenetic"—and +this merely on the ground that they have been shown +to be inherited or not inherited as the case may be. Now, +there need be no objection to such assumptions, provided<span class="pagenum"><a name="Page_337" id="Page_337">[Pg 337]</a></span> +they are recognized as assumptions; but so long as the very +question in debate has reference to their validity as assumptions, +it is closely illogical to adduce them as arguments. And this +is the only point with which we are at present concerned.</p> + + + + +<h2><span class="smcap">Note B to Page 89.</span></h2> + + +<p>In answer to this illustration as previously adduced by me, +Mr. Poulton has objected that the benefit arising from the +peculiar mode of stinging in question is a benefit conferred, +not on the insect which stings, but upon its progeny. The +point of the illustration however has no reference to the +maternal instinct (which here, as elsewhere, I doubt not is +due to natural selection); it has reference only to the particular +instinct of selective stinging, which here ministers to the purposes +of the other and more general instinct of rearing progeny. +Given then the maternal instinct of stinging prey for the use +of progeny, the question is—What first determined the ancestors +of the Sphex to sting their prey only in nine particular points? +Darwin's answer to this question is as follows:—</p> + +<blockquote><p>"I have been thinking about Pompilius and its allies. Please +take the trouble to read on perforation of the corolla by Bees, p. 425 +of my 'Cross-fertilization,' to end of chapter. Bees show so much +intelligence in their acts, that it seems not improbable to me that the +progenitors of Pompilius originally stung caterpillars and spiders, &c., +in any part of their bodies, and then observed by their intelligence +that if they stung them in one particular place, as between certain +segments on the lower side, their prey was at once paralyzed. It +does, not seem to me at all incredible that this action should then +become instinctive, i.e. memory transmitted from one generation +to another. It does not seem necessary to suppose that when +Pompilius stung its prey in the ganglion it intended or knew that +their prey would keep long alive. The development of the larvae +may have been subsequently modified in relation to their half-dead, +instead of wholly dead prey; supposing that the prey was at first +quite killed, which would have required much stinging. Turn this +over in your mind," &c.</p></blockquote><p><span class="pagenum"><a name="Page_338" id="Page_338">[Pg 338]</a></span></p> + +<p>Weismann, on the other hand, can only suppose that this +intensely specialized instinct had its origin in fortuitous variations +in the psychology of the species. But, neglecting the +consideration that, in order to become fixed as an instinct +by natural selection, the particular variation required must +have occurred in many different individuals, not only in the +first, but also in the sequent generations, the chances against +its occurring only once, or in but one single individual case, are +many thousands if not millions to one.</p> + +<hr class="chap" /> +<p class="pagenum"><a name="Page_339" id="Page_339">[Pg 339]</a></p> + + + + +<h2>INDEX</h2> + + +<ul class="index"> +<li class="ifrst">A.</li> + +<li class="indx">Acceleration and retardation, <a href="#Page_16">16</a>.</li> + +<li class="indx">Acquired characters, heredity of, <a href="#Page_39">39</a>, <a href="#Page_103">103</a>, <a href="#Page_133">133</a>.</li> + +<li class="indx">Adaptation, <a href="#Page_7">7</a>, <a href="#Page_13">13</a>, <a href="#Page_55">55</a>, <a href="#Page_62">62</a>, <a href="#Page_67">67</a>, <a href="#Page_71">71</a>, <a href="#Page_159">159</a>, <a href="#Page_165">165</a>;</li> +<li class="isub1">of species and of specific characters, <a href="#Page_166">166</a>.</li> + +<li class="indx"><span class="smcap">Allen</span>, Mr., referred to, <a href="#Page_209">209</a>.</li> + +<li class="indx"><i>All-sufficiency of Natural Selection</i>, referred to, <a href="#Page_65">65</a>, <a href="#Page_95">95</a>.</li> + +<li class="indx"><i>Alone with the Hairy Ainu</i>, referred to, <a href="#Page_26">26</a>.</li> + +<li class="indx">American and European trees compared, <a href="#Page_201">201</a>.</li> + +<li class="indx"><i>American Journal of Science</i>, referred to, <a href="#Page_273">273</a>.</li> + +<li class="indx"><i>American Naturalist</i>, referred to, <a href="#Page_35">35</a>, <a href="#Page_58">58</a>.</li> + +<li class="indx">Ammonites, species of, <a href="#Page_254">254</a>.</li> + +<li class="indx"><i>Animal Intelligence</i>, referred to, <a href="#Page_93">93</a>.</li> + +<li class="indx"><i>Animal Life</i>, referred to, <a href="#Page_101">101</a>.</li> + +<li class="indx"><i>Animal Life and Intelligence</i>, referred to, <a href="#Page_33">33</a>, <a href="#Page_36">36</a>.</li> + +<li class="indx"><i>Apparent Paradox in Mental Evolution</i>, referred to, <a href="#Page_90">90</a>.</li> + +<li class="indx">Appendages of Normandy and Irish pigs, <a href="#Page_188">188</a>.</li> + +<li class="indx">Articulation and inheritance, <a href="#Page_335">335</a>.</li> + +<li class="indx">Artistic faculties of man, <a href="#Page_27">27</a>.</li> + + +<li class="ifrst">B.</li> + +<li class="indx"><span class="smcap">Babington</span>, Prof., referred to, <a href="#Page_252">252</a>.</li> + +<li class="indx"><span class="smcap">Bachman</span>, Dr., referred to, <a href="#Page_186">186</a>.</li> + +<li class="indx"><span class="smcap">Bailey</span>, Prof., referred to, <a href="#Page_127">127</a>.</li> + +<li class="indx"><span class="smcap">Baker</span>, Mr., referred to, <a href="#Page_252">252</a>.</li> + +<li class="indx">Balancing of brainless frog, <a href="#Page_78">78</a>.</li> + +<li class="indx"><span class="smcap">Ball</span>, Mr. Platt, referred to, <a href="#Page_3">3</a>, <a href="#Page_95">95</a>; quoted, <a href="#Page_50">50</a>.</li> + +<li class="indx"><span class="smcap">Bateson</span>, Mr. W., referred to, <a href="#Page_36">36</a>.</li> + +<li class="indx"><span class="smcap">Beddard</span>, Mr. F., referred to, <a href="#Page_174">174</a>.</li> + +<li class="indx"><span class="smcap">Bentham</span>, Mr., referred to, <a href="#Page_252">252</a>.</li> + +<li class="indx">Birds, diagnostic characters of, <a href="#Page_176">176</a>;</li> +<li class="isub1">of Australia, effect of climate on, <a href="#Page_210">210</a>;</li> +<li class="isub1">influence of food on, <a href="#Page_218">218</a>.</li> + +<li class="indx">Blastogenetic, <a href="#Page_123">123</a>, <a href="#Page_242">242</a>, <a href="#Page_245">245</a>, <a href="#Page_250">250</a>.</li> + +<li class="indx">Blending of adaptations, <a href="#Page_67">67</a>.</li> + +<li class="indx"><i>Brain</i>, referred to, <a href="#Page_80">80</a>.</li> + +<li class="indx"><span class="smcap">Broca</span>, Prof., referred to, <a href="#Page_64">64</a>, <a href="#Page_67">67</a>, <a href="#Page_174">174</a>, <a href="#Page_318">318</a>.</li> + +<li class="indx"><span class="smcap">Bronn</span>, Prof., referred to, <a href="#Page_174">174</a>.</li> + +<li class="indx"><span class="smcap">Brooks</span>, Prof., referred to, <a href="#Page_14">14</a>.</li> + +<li class="indx"><span class="smcap">Brown-Séquard</span>, referred to, <a href="#Page_104">104</a>, <a href="#Page_122">122</a>, <a href="#Page_142">142</a>; quoted, <a href="#Page_104">104</a>.</li> + +<li class="indx"><span class="smcap">Buckley</span>, Mr., referred to, <a href="#Page_147">147</a>.</li> + +<li class="indx"><span class="smcap">Buckman</span>, Prof. James, referred to, <a href="#Page_125">125</a>.</li> + +<li class="indx"><span class="smcap">Buckman</span>, Prof. S.S., referred to, <a href="#Page_24">24</a>.</li> + +<li class="indx"><span class="smcap">Butler</span>, Mr. A. G., referred to, <a href="#Page_254">254</a>.</li> + +<li class="indx"><span class="smcap">Butler</span>, Mr. Samuel, referred to, <a href="#Page_87">87</a>.</li> + +<li class="indx">Butterfly, seasonal changes of, <a href="#Page_210">210</a>;</li> +<li class="isub1">influence of food on, <a href="#Page_217">217</a>.</li> + + +<li class="indx">C.</li> + +<li class="indx">Carnivora, instincts of, <a href="#Page_89">89</a>.</li> + +<li class="indx"><span class="pagenum"><a name="Page_340" id="Page_340">[Pg 340]</a></span><span class="smcap">Carrière</span>, M. L. A., referred to, <a href="#Page_123">123</a>.</li> + +<li class="indx">Cave animals, colour-changes in, <a href="#Page_211">211</a>.</li> + +<li class="indx"><i>Cave Fauna of North America</i>, quoted, <a href="#Page_211">211</a>.</li> + +<li class="indx">Cessation of Selection, <a href="#Page_99">99</a>, <a href="#Page_199">199</a>, <a href="#Page_212">212</a>, <a href="#Page_292">292</a>.</li> + +<li class="indx">Characters, adaptive and specific, <a href="#Page_159">159</a>, <a href="#Page_307">307</a>;</li> +<li class="isub1">specific, due to Natural Selection, <a href="#Page_171">171</a>.</li> + +<li class="indx"><i>Charadriidae, Geographical Distribution of the Family</i>, quoted, <a href="#Page_173">173</a>.</li> + +<li class="indx">Chimpanzee, counting of, <a href="#Page_31">31</a>.</li> + +<li class="indx">Climate, influence of, on plants, <a href="#Page_200">200</a>;</li> +<li class="isub1">on animals, <a href="#Page_209">209</a>.</li> + +<li class="indx">Co-adaptation, <a href="#Page_64">64</a>.</li> + +<li class="indx"><span class="smcap">Cockerell</span>, Prof., referred to, <a href="#Page_218">218</a>.</li> + +<li class="indx">Colour, <a href="#Page_269">269</a>.</li> + +<li class="indx">Colour-changes in butterflies, <a href="#Page_210">210</a>.</li> +<li class="isub1">in cave animals, <a href="#Page_211">211</a>.</li> + +<li class="indx"><i>Colours of Animals</i>, referred to, <a href="#Page_36">36</a>.</li> + +<li class="indx">Congenital, as opposed to acquired characters, <a href="#Page_134">134</a>.</li> + +<li class="indx">Constancy of characters not necessarily due to Natural Selection, <a href="#Page_186">186</a>.</li> + +<li class="indx"><i>Contemporary Review</i>, referred to, <a href="#Page_60">60</a>, <a href="#Page_65">65</a>, <a href="#Page_95">95</a></li> + +<li class="indx">Continuity of germ-plasm, <a href="#Page_44">44</a>, <a href="#Page_61">61</a>, <a href="#Page_133">133</a>;</li> +<li class="isub1">absolute and relative, <a href="#Page_134">134</a>, <a href="#Page_155">155</a>.</li> + +<li class="indx"><i>Contributions to the Theory of Natural Selection</i>, referred to, <a href="#Page_2">2</a>; quoted, <a href="#Page_180">180</a>.</li> + +<li class="indx"><span class="smcap">Cope</span>, Prof., referred to, <a href="#Page_14">14</a>, <a href="#Page_15">15</a>, <a href="#Page_20">20</a>, <a href="#Page_63">63</a>, <a href="#Page_256">256</a>; quoted, <a href="#Page_16">16</a>.</li> + +<li class="indx">Correlation, <a href="#Page_171">171</a>, <a href="#Page_184">184</a>, <a href="#Page_211">211</a>, <a href="#Page_222">222</a>, <a href="#Page_268">268</a>.</li> + +<li class="indx"><span class="smcap">Costa</span>, M., quoted, <a href="#Page_217">217</a>.</li> + +<li class="indx"><span class="smcap">Cunningham</span>, Mr. J. T., quoted, <a href="#Page_103">103</a>; referred to, <a href="#Page_95">95</a>, <a href="#Page_122">122</a>.</li> + + +<li class="ifrst">D.</li> + +<li class="indx"><span class="smcap">Dall</span>, Prof., referred to, <a href="#Page_14">14</a>.</li> + +<li class="indx"><span class="smcap">Darwin</span>, Charles, referred to, <a href="#Page_1">1</a>-<a href="#Page_13">13</a>, <a href="#Page_20">20</a>-<a href="#Page_22">22</a>, <a href="#Page_25">25</a>, <a href="#Page_44">44</a>, <a href="#Page_45">45</a>, <a href="#Page_51">51</a>-<a href="#Page_53">53</a>, <a href="#Page_56">56</a>, <a href="#Page_66">66</a>, <a href="#Page_67">67</a>, <a href="#Page_74">74</a>, <a href="#Page_87">87</a>, <a href="#Page_88">88</a>, <a href="#Page_93">93</a>, <a href="#Page_95">95</a>, <a href="#Page_96">96</a>-<a href="#Page_100">100</a>, <a href="#Page_149">149</a>, <a href="#Page_159">159</a>, <a href="#Page_160">160</a>, <a href="#Page_167">167</a>, <a href="#Page_173">173</a>, <a href="#Page_174">174</a>, <a href="#Page_181">181</a>-<a href="#Page_183">183</a>, <a href="#Page_187">187</a>-<a href="#Page_191">191</a>, <a href="#Page_193">193</a>, <a href="#Page_195">195</a>, <a href="#Page_198">198</a>, <a href="#Page_200">200</a>-<a href="#Page_202">202</a>, <a href="#Page_213">213</a>-<a href="#Page_216">216</a>, <a href="#Page_218">218</a>, <a href="#Page_219">219</a>, <a href="#Page_226">226</a>, <a href="#Page_256">256</a>, <a href="#Page_261">261</a>-<a href="#Page_265">265</a>, <a href="#Page_268">268</a>, <a href="#Page_271">271</a>, <a href="#Page_277">277</a>, <a href="#Page_283">283</a>, <a href="#Page_287">287</a>, <a href="#Page_291">291</a>, <a href="#Page_305">305</a>-<a href="#Page_307">307</a>, <a href="#Page_313">313</a>-<a href="#Page_332">332</a>, <a href="#Page_337">337</a>; quoted, <a href="#Page_11">11</a>, <a href="#Page_53">53</a>, <a href="#Page_66">66</a>, <a href="#Page_96">96</a>, <a href="#Page_181">181</a>, <a href="#Page_182">182</a>, <a href="#Page_186">186</a>-<a href="#Page_191">191</a>, <a href="#Page_193">193</a>, <a href="#Page_195">195</a>, <a href="#Page_201">201</a>, <a href="#Page_202">202</a>, <a href="#Page_213">213</a>-<a href="#Page_215">215</a>, <a href="#Page_261">261</a>, <a href="#Page_262">262</a>, <a href="#Page_265">265</a>, <a href="#Page_313">313</a>-<a href="#Page_316">316</a>, <a href="#Page_319">319</a>-<a href="#Page_322">322</a>, <a href="#Page_324">324</a>-<a href="#Page_326">326</a>, <a href="#Page_328">328</a>-<a href="#Page_331">331</a>, <a href="#Page_337">337</a>.</li> + +<li class="indx"><i>Darwin et ses Précurseurs Français</i>, referred to, <a href="#Page_234">234</a>.</li> + +<li class="indx"><i>Darwinian Theory of the Origin of Species</i>, quoted, <a href="#Page_254">254</a>.</li> + +<li class="indx"><i>Darwinism</i>, quoted, <a href="#Page_22">22</a>, <a href="#Page_27">27</a>, <a href="#Page_67">67</a>, <a href="#Page_181">181</a>, <a href="#Page_182">182</a>, <a href="#Page_186">186</a>, <a href="#Page_189">189</a>-<a href="#Page_191">191</a>, <a href="#Page_221">221</a>, <a href="#Page_222">222</a>, <a href="#Page_235">235</a>, <a href="#Page_236">236</a>, <a href="#Page_252">252</a>, <a href="#Page_253">253</a>, <a href="#Page_269">269</a>, <a href="#Page_270">270</a>, <a href="#Page_273">273</a>, <a href="#Page_313">313</a>, <a href="#Page_316">316</a>; referred to, <a href="#Page_7">7</a>, <a href="#Page_12">12</a>, <a href="#Page_15">15</a>, <a href="#Page_20">20</a>, <a href="#Page_70">70</a>.</li> + +<li class="indx"><span class="smcap">De Candolle</span>, Prof., referred to, <a href="#Page_206">206</a>.</li> + +<li class="indx">Deep-sea faunas, <a href="#Page_212">212</a>.</li> + +<li class="indx"><span class="smcap">Delbœuf</span>, referred to, <a href="#Page_224">224</a>.</li> + +<li class="indx"><i>Descent of Man</i>, quoted, <a href="#Page_25">25</a>, <a href="#Page_322">322</a>-<a href="#Page_324">324</a>, <a href="#Page_331">331</a>.</li> + +<li class="indx"><i>Development of the Hard Parts of the Mammalia</i>, referred to, <a href="#Page_14">14</a>.</li> + +<li class="indx"><span class="smcap">De Vries</span>, Prof., referred to, <a href="#Page_122">122</a>, <a href="#Page_174">174</a>.</li> + +<li class="indx">Diagnostic characters of birds, <a href="#Page_176">176</a>;</li> +<li class="isub1">Marsupials, <a href="#Page_178">178</a>.</li> + +<li class="indx">Divergent Evolution through Cumulative Segregation, quoted, <a href="#Page_224">224</a>.</li> + +<li class="indx"><span class="smcap">Dixon</span>, Mr. Charles, referred to, <a href="#Page_174">174</a>; quoted, <a href="#Page_177">177</a>, <a href="#Page_223">223</a>.</li> + +<li class="indx"><i>Doctrine of Descent and Darwinism</i>, quoted, <a href="#Page_260">260</a>.</li> + +<li class="indx">Dogs, scratching, reflex of, <a href="#Page_80">80</a>;</li> +<li class="isub1">shaking off water, <a href="#Page_84">84</a>;</li> +<li class="isub1">transplantation of ovaries, <a href="#Page_143">143</a>.</li> + +<li class="indx"><span class="smcap">Dorfmeister</span>, Dr., referred to, <a href="#Page_211">211</a>.</li> + +<li class="indx">Ducks, use-inheritance in, <a href="#Page_96">96</a>;</li> +<li class="isub1">losing true plumage, <a href="#Page_187">187</a>.</li> + +<li class="indx"><span class="smcap">Dupuy</span>, Dr., referred to, <a href="#Page_105">105</a>.</li> + +<li class="indx"><span class="smcap">Dyer</span>, Mr. Thistleton, quoted, <a href="#Page_325">325</a>, <a href="#Page_327">327</a>.</li> + + +<li class="ifrst">E.</li> + +<li class="indx"><span class="pagenum"><a name="Page_341" id="Page_341">[Pg 341]</a></span><i>Effect of External Influences upon Development</i>, referred to, <a href="#Page_66">66</a>, <a href="#Page_95">95</a>.</li> + +<li class="indx"><i>Effects of Use and Disuse</i>, quoted, <a href="#Page_50">50</a>.</li> + +<li class="indx"><span class="smcap">Eimer</span>, Prof., referred to, <a href="#Page_14">14</a>, <a href="#Page_174">174</a>, <a href="#Page_217">217</a>.</li> + +<li class="indx"><i>Entomological Society, Trans. of</i>, quoted, <a href="#Page_211">211</a>; referred to, <a href="#Page_217">217</a>.</li> + +<li class="indx">Epilepsy of guinea-pigs, <a href="#Page_104">104</a>.</li> + +<li class="indx"><i>Essays on Heredity</i>, quoted, <a href="#Page_56">56</a>, <a href="#Page_91">91</a>, <a href="#Page_97">97</a>, <a href="#Page_107">107</a>, <a href="#Page_152">152</a>; referred to, <a href="#Page_12">12</a>, <a href="#Page_36">36</a>, <a href="#Page_65">65</a>, <a href="#Page_105">105</a>, <a href="#Page_110">110</a>.</li> + +<li class="indx"><span class="smcap">Eudes-Deslongchamps, M.</span>, referred to, <a href="#Page_188">188</a>.</li> + +<li class="indx">European and American trees, compared, <a href="#Page_201">201</a>.</li> + +<li class="indx"><span class="smcap">Everest</span>, Rev. E., quoted, <a href="#Page_213">213</a>.</li> + +<li class="indx"><i>Evolution without Natural Selection</i>, quoted, <a href="#Page_177">177</a>.</li> + +<li class="indx"><i>Examination of Weismannism</i>, referred to, <a href="#Page_39">39</a>-<a href="#Page_42">42</a>, <a href="#Page_44">44</a>, <a href="#Page_100">100</a>, <a href="#Page_122">122</a>, <a href="#Page_123">123</a>, <a href="#Page_134">134</a>, <a href="#Page_136">136</a>, <a href="#Page_138">138</a>-<a href="#Page_140">140</a>, <a href="#Page_156">156</a>.</li> + +<li class="indx"><i>Experiments in Pangenesis</i>, referred to, <a href="#Page_145">145</a>.</li> + + +<li class="ifrst">F.</li> + +<li class="indx"><span class="smcap">Fabre, M.</span>, referred to, <a href="#Page_88">88</a>.</li> + +<li class="indx">Factors of organic evolution:</li> +<li class="isub1">Natural Selection, <a href="#Page_2">2</a>, <a href="#Page_5">5</a>, <a href="#Page_6">6</a>;</li> +<li class="isub1">use-inheritance, <a href="#Page_3">3</a>, <a href="#Page_11">11</a>.</li> + +<li class="indx"><i>Factors of Organic Evolution</i>, referred to, <a href="#Page_8">8</a>.</li> + +<li class="indx">Faculties and organs, <a href="#Page_29">29</a>.</li> + +<li class="indx">Fertility, <a href="#Page_229">229</a>.</li> + +<li class="indx">Flat-fish, Mr. Cunningham on, <a href="#Page_103">103</a>.</li> + +<li class="indx"><i>Floral Structures</i>, referred to, <a href="#Page_19">19</a>.</li> + +<li class="indx"><span class="smcap">Focke</span>, Dr., referred to, <a href="#Page_174">174</a>.</li> + +<li class="indx"><i>Fonctions du Cerveau</i>, referred to, <a href="#Page_109">109</a>.</li> + +<li class="indx">Food, influence of, <a href="#Page_217">217</a>.</li> + +<li class="indx">Foot, of man, <a href="#Page_23">23</a>.</li> + +<li class="indx">Frog, brainless, balancing of, <a href="#Page_78">78</a>.</li> + + +<li class="ifrst">G.</li> + +<li class="indx"><span class="smcap">Galton</span>, Mr. Francis, referred to, <a href="#Page_40">40</a>-<a href="#Page_48">48</a>, <a href="#Page_100">100</a>, <a href="#Page_103">103</a>, <a href="#Page_134">134</a>-<a href="#Page_139">139</a>, <a href="#Page_145">145</a>, <a href="#Page_146">146</a>, <a href="#Page_152">152</a>, <a href="#Page_154">154</a>, <a href="#Page_156">156</a>, <a href="#Page_300">300</a>, <a href="#Page_303">303</a>-<a href="#Page_305">305</a>; quoted, <a href="#Page_46">46</a>, <a href="#Page_100">100</a>.</li> + +<li class="indx">Gangrene, effects of, <a href="#Page_54">54</a>, <a href="#Page_105">105</a>.</li> + +<li class="indx"><i>Gardener's Chronicle</i>, quoted, <a href="#Page_127">127</a>.</li> + +<li class="indx"><span class="smcap">Gärtner</span>, Dr., referred to, <a href="#Page_206">206</a>.</li> + +<li class="indx"><span class="smcap">Geddes</span>, Prof., referred to, <a href="#Page_15">15</a>, <a href="#Page_20">20</a>,<a href="#Page_174">174</a>.</li> + +<li class="indx">Gemmules, <a href="#Page_47">47</a>, <a href="#Page_145">145</a>, <a href="#Page_155">155</a>.</li> + +<li class="indx">Genera and species, <a href="#Page_261">261</a>.</li> + +<li class="indx">Germ-plasm and Stirp, <a href="#Page_40">40</a>;</li> +<li class="isub1">and pangenesis, <a href="#Page_42">42</a>;</li> +<li class="isub1">isolation of, <a href="#Page_137">137</a>;</li> +<li class="isub1">stability of, <a href="#Page_243">243</a>.</li> + +<li class="indx"><i>Germ-plasm</i>, referred to, <a href="#Page_128">128</a>.</li> + +<li class="indx"><span class="smcap">Giard</span>, Prof., referred to, <a href="#Page_14">14</a>, <a href="#Page_174">174</a>.</li> + +<li class="indx">Giraffe, co-adaptation in, <a href="#Page_64">64</a>.</li> + +<li class="indx"><span class="smcap">Goltz</span>, Prof., referred to, <a href="#Page_80">80</a>, <a href="#Page_84">84</a>.</li> + +<li class="indx"><span class="smcap">Gould</span>, Mr., referred to, <a href="#Page_210">210</a>.</li> + +<li class="indx">Graft-hybridization, <a href="#Page_143">143</a>.</li> + +<li class="indx">Growth, laws of, <a href="#Page_222">222</a>, <a href="#Page_226">226</a>, <a href="#Page_248">248</a>, <a href="#Page_270">270</a>, <a href="#Page_321">321</a>.</li> + +<li class="indx">Guinea-pigs, epilepsy of, <a href="#Page_104">104</a>.</li> + +<li class="indx"><span class="smcap">Gulick</span>, Mr., referred to, <a href="#Page_174">174</a>, <a href="#Page_259">259</a>, <a href="#Page_260">260</a>, <a href="#Page_271">271</a>; quoted, <a href="#Page_224">224</a>, <a href="#Page_273">273</a>.</li> + +<li class="indx"><i>Gute und schlechte Arten</i>, quoted, <a href="#Page_203">203</a>.</li> + + +<li class="ifrst">H.</li> + +<li class="indx">Habit, hereditary, <a href="#Page_87">87</a>.</li> + +<li class="indx"><i>Habit and Intelligence</i>, quoted, <a href="#Page_225">225</a>.</li> + +<li class="indx">Hand, of man, <a href="#Page_24">24</a>.</li> + +<li class="indx"><i>Handbook of British Flora</i>, referred to, <a href="#Page_252">252</a>.</li> + +<li class="indx"><span class="smcap">Haycraft</span>, Prof., referred to, <a href="#Page_80">80</a>.</li> + +<li class="indx"><span class="smcap">Heape</span>, Mr. Walter, referred to, <a href="#Page_147">147</a>.</li> + +<li class="indx"><span class="smcap">Henslow</span>, Prof. George, referred to, <a href="#Page_18">18</a>-<a href="#Page_20">20</a>, <a href="#Page_127">127</a>-<a href="#Page_132">132</a>, <a href="#Page_174">174</a>, <a href="#Page_208">208</a>; quoted, <a href="#Page_19">19</a>, <a href="#Page_130">130</a>, <a href="#Page_131">131</a>.</li> + +<li class="indx">Heredity, problems of, <a href="#Page_39">39</a>.</li> + +<li class="indx"><span class="smcap">Hering</span>, Prof., referred to, <a href="#Page_87">87</a>.</li> + +<li class="indx"><span class="smcap">Hewitt</span>, Mr., referred to, <a href="#Page_187">187</a>.</li> + +<li class="indx"><span class="smcap">Hill</span>, Prof. Leonard, quoted, <a href="#Page_132">132</a>.</li> + +<li class="indx"><span class="smcap">Haeckel</span>, Prof., referred to, <a href="#Page_174">174</a>, <a href="#Page_260">260</a>, <a href="#Page_282">282</a>.</li> + +<li class="indx"><span class="smcap">Hoffmann</span>, Dr., referred to, <a href="#Page_123">123</a>, <a href="#Page_280">280</a>.</li> + +<li class="indx">Horse, callosities of, <a href="#Page_265">265</a>.</li> + +<li class="indx"><span class="smcap">Huxley</span>, Prof. T. H., referred to, <a href="#Page_167">167</a>-<a href="#Page_170">170</a>, <a href="#Page_185">185</a>, <a href="#Page_256">256</a>, <a href="#Page_275">275</a>, <a href="#Page_283">283</a>, <a href="#Page_307">307</a>-<a href="#Page_312">312</a>; quoted, <a href="#Page_307">307</a>-<a href="#Page_309">309</a>.</li> + +<li class="indx">Huxleyan doctrine of species, <a href="#Page_167">167</a>.</li> + +<li class="indx"><i>Hyatt</i>, Prof., referred to, <a href="#Page_14">14</a>, <a href="#Page_15">15</a>.</li> + +<li class="indx">Hymenoptera, social, <a href="#Page_92">92</a>.</li> + + +<li class="ifrst">I.</li> + +<li class="indx"><i>Inadequacy of Natural Selection</i>, referred to, <a href="#Page_65">65</a>, <a href="#Page_95">95</a>.</li> + +<li class="indx"><span class="pagenum"><a name="Page_342" id="Page_342">[Pg 342]</a></span><i>Inconsistencies of Utilitarianism as the Exclusive Theory of Organic Evolution</i>, quoted, <a href="#Page_273">273</a>.</li> + +<li class="indx">Indifferent characters, <a href="#Page_171">171</a>, <a href="#Page_185">185</a>, <a href="#Page_208">208</a>, <a href="#Page_247">247</a>.</li> + +<li class="indx">Insects, instincts of, <a href="#Page_91">91</a>.</li> + +<li class="indx">Instability of useless characters, <a href="#Page_186">186</a>.</li> + +<li class="indx">Instinct and hereditary habit, <a href="#Page_87">87</a>;</li> +<li class="isub1">of Sphex, <a href="#Page_88">88</a>;</li> +<li class="isub1">of carnivora, <a href="#Page_89">89</a>;</li> +<li class="isub1">of man, <a href="#Page_89">89</a>;</li> +<li class="isub1">Prof. Weismann's views on, <a href="#Page_90">90</a>;</li> +<li class="isub1">of insects, <a href="#Page_91">91</a>.</li> + +<li class="indx">Intercrossing, <a href="#Page_67">67</a>-<a href="#Page_71">71</a>.</li> + +<li class="indx">Isolation, <a href="#Page_223">223</a> <i>et seq.</i></li> + + +<li class="ifrst">J.</li> + +<li class="indx"><span class="smcap">Jordan</span>, Dr., referred to, <a href="#Page_206">206</a>, <a href="#Page_252">252</a>.</li> + + +<li class="ifrst">K.</li> + +<li class="indx">Karyokinesis, <a href="#Page_140">140</a>.</li> + +<li class="indx"><span class="smcap">Kerner</span>, Prof., referred to, <a href="#Page_174">174</a>, <a href="#Page_202">202</a>-<a href="#Page_206">206</a>, <a href="#Page_231">231</a>, <a href="#Page_239">239</a>, <a href="#Page_260">260</a>, <a href="#Page_282">282</a>; quoted, <a href="#Page_203">203</a>.</li> + +<li class="indx"><span class="smcap">Koch</span>, Dr., referred to, <a href="#Page_217">217</a>.</li> + +<li class="indx"><span class="smcap">Kölliker</span>, Prof., referred to, <a href="#Page_174">174</a>.</li> + + +<li class="ifrst">L.</li> + +<li class="indx">Lamarck, referred to, <a href="#Page_9">9</a>-<a href="#Page_15">15</a>.</li> + +<li class="indx">Lamarckism, <a href="#Page_9">9</a>, <a href="#Page_61">61</a>, <a href="#Page_113">113</a>.</li> + +<li class="indx"><span class="smcap">Landor</span>, A. H. Savage, referred to, <a href="#Page_26">26</a>.</li> + +<li class="indx">Language and Weismannism, <a href="#Page_334">334</a>.</li> + +<li class="indx"><span class="smcap">Lankester</span>, Prof. Ray, quoted, <a href="#Page_245">245</a>, <a href="#Page_299">299</a>; referred to, <a href="#Page_305">305</a>.</li> + +<li class="indx"><span class="smcap">Lesage</span>, M., referred to, <a href="#Page_126">126</a>.</li> + +<li class="indx"><i>Life and Letters of Charles Darwin</i>, quoted, <a href="#Page_319">319</a>, <a href="#Page_320">320</a>; referred to, <a href="#Page_11">11</a>.</li> + +<li class="indx"><span class="smcap">Luciani</span>, referred to, <a href="#Page_109">109</a>.</li> + + +<li class="ifrst">M.</li> + +<li class="indx"><i>Making of Flowers</i>, referred to, <a href="#Page_19">19</a>.</li> + +<li class="indx"><i>Manual of British Botany</i>, referred to, <a href="#Page_252">252</a>.</li> + +<li class="indx"><i>Manual of Dental Anatomy</i>, figure from, <a href="#Page_267">267</a>.</li> + +<li class="indx">Marsupials, diagnostic characters of, <a href="#Page_178">178</a>.</li> + +<li class="indx"><i>Materials for the Study of Variation</i>, referred to, <a href="#Page_36">36</a>.</li> + +<li class="indx"><span class="smcap">Meehan</span>, Mr., referred to, <a href="#Page_201">201</a>.</li> + +<li class="indx"><span class="smcap">Meldola</span>, Prof., referred to, <a href="#Page_68">68</a>.</li> + +<li class="indx"><i>Mental Evolution in Animals</i>, referred to, <a href="#Page_25">25</a>, <a href="#Page_88">88</a>, <a href="#Page_89">89</a>, <a href="#Page_92">92</a>.</li> + +<li class="indx"><i>Mental Evolution in Man</i>, referred to, <a href="#Page_31">31</a>.</li> + +<li class="indx"><span class="smcap">Merrifield</span>, Mr., referred to, <a href="#Page_211">211</a>.</li> + +<li class="indx">Mice, mutilation of tails of, <a href="#Page_148">148</a>.</li> + +<li class="indx"><span class="smcap">Mivart</span>, Prof. St. George, referred to, <a href="#Page_4">4</a>, <a href="#Page_174">174</a>, <a href="#Page_217">217</a>.</li> + +<li class="indx">Monstrosity, in turkeys, <a href="#Page_181">181</a>;</li> +<li class="isub1">in cattle, <a href="#Page_196">196</a>.</li> + +<li class="indx"><span class="smcap">Morgan</span>, Prof. Lloyd, referred to, <a href="#Page_33">33</a>, <a href="#Page_36">36</a>, <a href="#Page_174">174</a>, <a href="#Page_271">271</a>, <a href="#Page_300">300</a>-<a href="#Page_305">305</a>; quoted, <a href="#Page_300">300</a>, <a href="#Page_303">303</a>.</li> + +<li class="indx"><span class="smcap">Moseley</span>, Prof., referred to, <a href="#Page_26">26</a>.</li> + +<li class="indx"><span class="smcap">Murphy</span>, Mr. J. J., referred to, <a href="#Page_224">224</a>.</li> + +<li class="indx">Mutilations, inheritance of, <a href="#Page_53">53</a>, <a href="#Page_148">148</a>.</li> + + +<li class="ifrst">N.</li> + +<li class="indx"><span class="smcap">Nägeli</span>, Prof., referred to, <a href="#Page_174">174</a>, <a href="#Page_206">206</a>, <a href="#Page_318">318</a>.</li> + +<li class="indx">Naked skin of man, <a href="#Page_25">25</a>.</li> + +<li class="indx"><span class="smcap">Nathusius</span>, referred to, <a href="#Page_188">188</a>.</li> + +<li class="indx">Natural Selection, range of, <a href="#Page_2">2</a>, <a href="#Page_5">5</a>, <a href="#Page_51">51</a>, <a href="#Page_62">62</a>, <a href="#Page_92">92</a>;</li> +<li class="isub1">a theory of species, <a href="#Page_161">161</a>, <a href="#Page_169">169</a>;</li> +<li class="isub1">and cave animals, <a href="#Page_211">211</a>;</li> +<li class="isub1">and Porto Santo rabbits, <a href="#Page_214">214</a>.</li> + +<li class="indx"><i>Natural Selection and Tropical Nature</i>, quoted, <a href="#Page_23">23</a>.</li> + +<li class="indx"><i>Natural Science</i>, quoted, <a href="#Page_104">104</a>.</li> + +<li class="indx"><i>Nature</i>, quoted, <a href="#Page_132">132</a>, <a href="#Page_223">223</a>, <a href="#Page_245">245</a>, <a href="#Page_299">299</a>, <a href="#Page_325">325</a>; referred to, <a href="#Page_68">68</a>, <a href="#Page_98">98</a>, <a href="#Page_218">218</a>.</li> + +<li class="indx">Neo-Darwinian school, <a href="#Page_10">10</a>, <a href="#Page_61">61</a>.</li> + +<li class="indx">Neo-Lamarckian school, <a href="#Page_13">13</a>, <a href="#Page_62">62</a>, <a href="#Page_63">63</a>.</li> + +<li class="indx"><i>Neuer Beitrag zum geologischen Beweis der Darwin'schen Theorie</i>, quoted, <a href="#Page_254">254</a>.</li> + +<li class="indx"><i>Neuter Insects and Darwinism</i>, referred to, <a href="#Page_95">95</a>.</li> + +<li class="indx"><i>Neuter Insects and Lamarckism</i>, referred to, <a href="#Page_95">95</a>.</li> + +<li class="indx">Neuters of hymenopterous insects, <a href="#Page_92">92</a>.</li> + +<li class="indx"><span class="smcap">Newman</span>, Cardinal, referred to, <a href="#Page_20">20</a>.</li> + +<li class="indx">Niata cattle, <a href="#Page_191">191</a>.</li> + + +<li class="ifrst">O.</li> + +<li class="indx"><span class="smcap">Obersteiner</span>, Dr., referred to, <a href="#Page_105">105</a>, <a href="#Page_106">106</a>.</li> + +<li class="indx"><span class="pagenum"><a name="Page_343" id="Page_343">[Pg 343]</a></span><i>Oesterreichische medicinische Jahrbücher</i>, referred to, <a href="#Page_105">105</a>.</li> + +<li class="indx"><i>On Truth</i>, referred to, <a href="#Page_217">217</a>.</li> + +<li class="indx">Orang-utan, teeth of, <a href="#Page_267">267</a>.</li> + +<li class="indx"><i>Organic Evolution</i>, referred to, <a href="#Page_217">217</a>.</li> + +<li class="indx"><i>Origin of the Fittest</i>, quoted, <a href="#Page_16">16</a>; referred to, <a href="#Page_14">14</a>.</li> + +<li class="indx"><i>Origine des Plantes Domestiques, démontrée par la culture du Radis sauvage</i>, referred to, <a href="#Page_123">123</a>.</li> + +<li class="indx"><i>Origin of Sex</i>, referred to, <a href="#Page_17">17</a>.</li> + +<li class="indx"><i>Origin of Species</i>, quoted, <a href="#Page_3">3</a>, <a href="#Page_4">4</a>, <a href="#Page_181">181</a>, <a href="#Page_182">182</a>, <a href="#Page_186">186</a>, <a href="#Page_188">188</a>, <a href="#Page_190">190</a>, <a href="#Page_261">261</a>, <a href="#Page_262">262</a>, <a href="#Page_265">265</a>, <a href="#Page_321">321</a>, <a href="#Page_322">322</a>, <a href="#Page_325">325</a>, <a href="#Page_326">326</a>, <a href="#Page_329">329</a>; referred to, <a href="#Page_67">67</a>, <a href="#Page_159">159</a>, <a href="#Page_227">227</a>, <a href="#Page_286">286</a>.</li> + +<li class="indx"><span class="smcap">Osborn</span>, Prof., referred to, <a href="#Page_14">14</a>, <a href="#Page_58">58</a>, <a href="#Page_63">63</a>.</li> + +<li class="indx"><span class="smcap">Owen</span>, Sir Richard, referred to, <a href="#Page_191">191</a>.</li> + +<li class="indx">Oxen, skulls of, compared, <a href="#Page_192">192</a>.</li> + +<li class="indx">Oysters, change of, <a href="#Page_217">217</a>.</li> + + +<li class="ifrst">P.</li> + +<li class="indx"><span class="smcap">Packard</span>, Prof., referred to, <a href="#Page_14">14</a>, <a href="#Page_213">213</a>.</li> + +<li class="indx">Pangenesis, <a href="#Page_11">11</a>, <a href="#Page_42">42</a>.</li> + +<li class="indx">Panmixia, <a href="#Page_97">97</a>, <a href="#Page_212">212</a>, <a href="#Page_291">291</a>.</li> + +<li class="indx">Parsimony, law of, <a href="#Page_51">51</a>.</li> + +<li class="indx">Parsnips, variation of, <a href="#Page_125">125</a>.</li> + +<li class="indx"><span class="smcap">Pascoe</span>, Mr., referred to, <a href="#Page_174">174</a>; quoted, <a href="#Page_254">254</a>.</li> + +<li class="indx"><span class="smcap">Perrier</span>, Prof., referred to, <a href="#Page_14">14</a>, <a href="#Page_93">93</a>, <a href="#Page_95">95</a>.</li> + +<li class="indx"><span class="smcap">Peter</span>, Dr., referred to, <a href="#Page_206">206</a>.</li> + +<li class="indx"><span class="smcap">Pfeffer</span>, Herr, referred to, <a href="#Page_15">15</a>.</li> + +<li class="indx"><i>Pflüger's Archiv</i>, referred to, <a href="#Page_80">80</a>.</li> + +<li class="indx"><i>Philosophical Transactions</i>, referred <a href="#Page_10">10</a>, <a href="#Page_103">103</a>.</li> + +<li class="indx"><i>Physiological Selection</i>, referred to, <a href="#Page_187">187</a>, <a href="#Page_307">307</a>, <a href="#Page_313">313</a>, <a href="#Page_324">324</a>; quoted, <a href="#Page_188">188</a>, <a href="#Page_308">308</a>.</li> + +<li class="indx"><i>Pickard-Cambridge</i>, Rev. O., quoted, <a href="#Page_221">221</a>.</li> + +<li class="indx">Pig, old Irish, <a href="#Page_188">188</a>.</li> + +<li class="indx">Plants, influence of climate on, <a href="#Page_122">122</a>-<a href="#Page_207">207</a>.</li> + +<li class="indx">Porto Santo rabbits, <a href="#Page_214">214</a>.</li> + +<li class="indx"><span class="smcap">Poulton</span>, E. B., referred to, <a href="#Page_36">36</a>, <a href="#Page_217">217</a>, <a href="#Page_337">337</a>.</li> + +<li class="indx"><i>Presidential Address to the Bristol Naturalists Society</i>, 1891; quoted, <a href="#Page_300">300</a>, <a href="#Page_303">303</a>.</li> + +<li class="indx"><i>Proceedings of the Royal Society</i>, referred to, <a href="#Page_145">145</a>, <a href="#Page_147">147</a>; quoted, <a href="#Page_307">307</a>.</li> + +<li class="indx">Protective resemblance, <a href="#Page_72">72</a>.</li> + +<li class="indx">Protrusion of eyeball, in epileptic guinea-pigs, <a href="#Page_111">111</a>.</li> + + +<li class="ifrst">Q.</li> + +<li class="indx"><span class="smcap">Quatrefages</span>, M., referred to, <a href="#Page_234">234</a>.</li> + + +<li class="indx">R.</li> + +<li class="indx">Rabbits, and use-inheritance, <a href="#Page_96">96</a>;</li> +<li class="isub1">transplantation of ovaries, <a href="#Page_143">143</a>;</li> +<li class="isub1">Porto Santo, <a href="#Page_214">214</a>.</li> + +<li class="indx">Radish, variation of, <a href="#Page_123">123</a>.</li> + +<li class="indx">Rats, scratching, reflex of, <a href="#Page_81">81</a>.</li> + +<li class="indx"><i>Raupen und Schmetterlinge der Wetterau</i>, referred to, <a href="#Page_217">217</a>.</li> + +<li class="indx">Reflex action and use-inheritance, <a href="#Page_64">64</a>-<a href="#Page_87">87</a>.</li> + +<li class="indx"><i>Rejoinder to Prof. Weismann</i>, referred to, <a href="#Page_95">95</a>.</li> + +<li class="indx">Reversal of selection, <a href="#Page_101">101</a>, <a href="#Page_292">292</a>.</li> + +<li class="indx"><i>Revue Générale de Botanie</i>, referred to, <a href="#Page_126">126</a>.</li> + +<li class="indx"><span class="smcap">Richardson</span>, referred to, <a href="#Page_188">188</a>.</li> + +<li class="indx"><span class="smcap">Roux</span>, Prof., referred to, <a href="#Page_298">298</a>.</li> + +<li class="indx">Rudiments, <a href="#Page_294">294</a>.</li> + +<li class="indx"><span class="smcap">Ryder</span>, Prof., referred to, <a href="#Page_14">14</a>.</li> + + +<li class="ifrst">S.</li> + +<li class="indx"><span class="smcap">Sachs</span>, Prof., referred to, <a href="#Page_15">15</a>, <a href="#Page_174">174</a>.</li> + +<li class="indx">"Sally," counting of, <a href="#Page_31">31</a>.</li> + +<li class="indx"><span class="smcap">Sauermann</span>, Dr., referred to, <a href="#Page_218">218</a>.</li> + +<li class="indx"><span class="smcap">Schäfer</span>, Prof., referred to, <a href="#Page_145">145</a>.</li> + +<li class="indx"><i>Schmetterlinge des Südwestlichen Deutschlands</i>, referred to, <a href="#Page_217">217</a>.</li> + +<li class="indx"><span class="smcap">Schmidt</span>, Dr. Oscar, quoted, <a href="#Page_260">260</a>.</li> + +<li class="indx">Schools of Evolutionists, <a href="#Page_12">12</a>-<a href="#Page_20">20</a>.</li> + +<li class="indx"><span class="smcap">Scott</span>, Prof., referred to, <a href="#Page_63">63</a>.</li> + +<li class="indx">Scratching, reflex, in dogs, <a href="#Page_80">80</a>;</li> +<li class="isub1">in rats, <a href="#Page_81">81</a>.</li> + +<li class="indx">Seasonal changes of butterflies, <a href="#Page_210">210</a>.</li> + +<li class="indx"><span class="smcap">Seebohm</span>, Mr. Henry, quoted, <a href="#Page_173">173</a>; referred to, <a href="#Page_174">174</a>.</li> + +<li class="indx">Selection, cessation of, <a href="#Page_99">99</a>, <a href="#Page_292">292</a>;</li> +<li class="isub1">reversal of, <a href="#Page_101">101</a>, <a href="#Page_292">292</a>.</li> + +<li class="indx">Selection, sexual, <a href="#Page_219">219</a> <i>et seq.</i></li> + +<li class="indx">Selective value, <a href="#Page_73">73</a>.</li> + +<li class="indx">Self-adaptation, <a href="#Page_18">18</a>.</li> + +<li class="indx"><span class="smcap">Semper</span>, Prof. Karl, referred to, <a href="#Page_101">101</a>.</li> + +<li class="indx"><span class="pagenum"><a name="Page_344" id="Page_344">[Pg 344]</a></span>Sexual selection, <a href="#Page_219">219</a> <i>et seq.</i></li> + +<li class="indx">Sole, pigment of, <a href="#Page_104">104</a>.</li> + +<li class="indx">Somatogenetic and somatoplasm, <a href="#Page_123">123</a>, <a href="#Page_137">137</a>, <a href="#Page_155">155</a>, <a href="#Page_242">242</a>-<a href="#Page_249">249</a>.</li> + +<li class="indx"><i>Some Laws of Heredity</i>, referred to, <a href="#Page_24">24</a>.</li> + +<li class="indx">Species, stress laid on origin of, <a href="#Page_159">159</a>;</li> +<li class="isub1">necessarily due to natural selection, <a href="#Page_168">168</a>.</li> + +<li class="indx">---- definitions of, <a href="#Page_229">229</a>.</li> + +<li class="indx"><span class="smcap">Spencer</span>, Herbert, referred to, <a href="#Page_8">8</a>, <a href="#Page_64">64</a>-<a href="#Page_68">68</a>, <a href="#Page_95">95</a>.</li> + +<li class="indx">Sphex, instincts of, <a href="#Page_88">88</a>, <a href="#Page_337">337</a>.</li> + +<li class="indx"><span class="smcap">Stebbing</span>, Rev. T. R., quoted, <a href="#Page_25">25</a>.</li> + +<li class="indx">Sterility, <a href="#Page_8">8</a>.</li> + +<li class="indx">Stirp and germ-plasm, <a href="#Page_40">40</a>, <a href="#Page_47">47</a>, <a href="#Page_138">138</a>.</li> + +<li class="indx"><i>Struggle for Existence between the parts of an Organism</i>, referred to, <a href="#Page_299">299</a>.</li> + + +<li class="indx">T.</li> + +<li class="indx">Theory of Heredity, referred to, <a href="#Page_40">40</a>, <a href="#Page_47">47</a>, <a href="#Page_137">137</a>, <a href="#Page_154">154</a>; quoted, <a href="#Page_46">46</a>, <a href="#Page_47">47</a>.</li> + +<li class="indx"><span class="smcap">Thomas</span>, Mr. Oldfield, referred to, <a href="#Page_178">178</a>.</li> + +<li class="indx"><span class="smcap">Thomson</span>, J. A., referred to, <a href="#Page_15">15</a>.</li> + +<li class="indx"><span class="smcap">Todd</span>, J. E., referred to, <a href="#Page_35">35</a>.</li> + +<li class="indx"><span class="smcap">Tomes</span>, Mr., referred to, <a href="#Page_267">267</a>.</li> + +<li class="indx">Transfusion of blood in rabbits, <a href="#Page_145">145</a>.</li> + +<li class="indx">Transplantation of ovaries in rabbits, <a href="#Page_143">143</a>, <a href="#Page_147">147</a>.</li> + +<li class="indx">Trees, comparison of European and American, <a href="#Page_201">201</a>.</li> + +<li class="indx">Turkey, tuft of hair of, <a href="#Page_181">181</a>;</li> +<li class="isub1">losing metallic tints, <a href="#Page_186">186</a>.</li> + + +<li class="indx">U.</li> + +<li class="indx">Use-inheritance, <a href="#Page_3">3</a>, <a href="#Page_49">49</a>, <a href="#Page_77">77</a>, <a href="#Page_95">95</a>, <a href="#Page_151">151</a>.</li> + +<li class="indx">Utility, law of, <a href="#Page_8">8</a>, <a href="#Page_20">20</a>, <a href="#Page_159">159</a>;</li> +<li class="isub1">universality of, <a href="#Page_166">166</a>;</li> +<li class="isub1">of specific characters, <a href="#Page_172">172</a>;</li> +<li class="isub1">of specific characters in birds, <a href="#Page_176">176</a>;</li> +<li class="isub1">of specific characters in Mammals, <a href="#Page_178">178</a>.</li> + + +<li class="ifrst">V.</li> + +<li class="indx"><i>Variation of Animals and Plants under Domestication</i>, quoted, <a href="#Page_3">3</a>, <a href="#Page_4">4</a>, <a href="#Page_53">53</a>, <a href="#Page_66">66</a>, <a href="#Page_96">96</a>, <a href="#Page_187">187</a>, <a href="#Page_189">189</a>, <a href="#Page_191">191</a>, <a href="#Page_193">193</a>, <a href="#Page_195">195</a>, <a href="#Page_213">213</a>-<a href="#Page_216">216</a>, <a href="#Page_330">330</a>, <a href="#Page_331">331</a>.</li> + +<li class="indx">Varieties, climatic, <a href="#Page_228">228</a>.</li> + +<li class="indx">Vestigial characters, <a href="#Page_171">171</a>, <a href="#Page_184">184</a>, <a href="#Page_261">261</a>, <a href="#Page_294">294</a>.</li> + +<li class="indx"><span class="smcap">Vines</span>, Prof., referred to, <a href="#Page_297">297</a>.</li> + +<li class="indx">Vitality, plumes of birds due to surplus, <a href="#Page_270">270</a>, <a href="#Page_25">25</a>.</li> + +<li class="indx">Voice, of man, <a href="#Page_25">25</a>.</li> + + +<li class="ifrst">W.</li> + +<li class="indx"><span class="smcap">Wagner</span>, Moritz, referred to, <a href="#Page_217">217</a>.</li> + +<li class="indx"><span class="smcap">Wallace</span>, Mr. A. R., referred to, <a href="#Page_2">2</a>, <a href="#Page_6">6</a>, <a href="#Page_9">9</a>, <a href="#Page_11">11</a>, <a href="#Page_15">15</a>, <a href="#Page_20">20</a>-<a href="#Page_35">35</a>, <a href="#Page_50">50</a>, <a href="#Page_66">66</a>-<a href="#Page_70">70</a>, <a href="#Page_167">167</a>, <a href="#Page_169">169</a>, <a href="#Page_172">172</a>-<a href="#Page_175">175</a>, <a href="#Page_180">180</a>-<a href="#Page_198">198</a>, <a href="#Page_210">210</a>, <a href="#Page_218">218</a>-<a href="#Page_227">227</a>, <a href="#Page_235">235</a>-<a href="#Page_237">237</a>, <a href="#Page_252">252</a>, <a href="#Page_256">256</a>, <a href="#Page_258">258</a>, <a href="#Page_263">263</a>-<a href="#Page_278">278</a>, <a href="#Page_285">285</a>, <a href="#Page_313">313</a>-<a href="#Page_322">322</a>, <a href="#Page_328">328</a>, <a href="#Page_331">331</a>, <a href="#Page_332">332</a>; quoted, <a href="#Page_22">22</a>-<a href="#Page_24">24</a>, <a href="#Page_27">27</a>, <a href="#Page_67">67</a>, <a href="#Page_180">180</a>-<a href="#Page_182">182</a>, <a href="#Page_185">185</a>, <a href="#Page_186">186</a>, <a href="#Page_190">190</a>, <a href="#Page_191">191</a>, <a href="#Page_221">221</a>-<a href="#Page_223">223</a>, <a href="#Page_235">235</a>, <a href="#Page_236">236</a>, <a href="#Page_269">269</a>, <a href="#Page_273">273</a>, <a href="#Page_313">313</a>.</li> + +<li class="indx">Wallacean doctrine of species, <a href="#Page_167">167</a>, <a href="#Page_169">169</a>.</li> + +<li class="indx"><span class="smcap">Weismann</span>, Prof., referred to, <a href="#Page_2">2</a>, <a href="#Page_7">7</a>, <a href="#Page_9">9</a>, <a href="#Page_12">12</a>, <a href="#Page_13">13</a>, <a href="#Page_39">39</a>-<a href="#Page_60">60</a>, <a href="#Page_65">65</a>, <a href="#Page_66">66</a>, <a href="#Page_90">90</a>-<a href="#Page_105">105</a>, <a href="#Page_112">112</a>, <a href="#Page_128">128</a>, <a href="#Page_134">134</a>-<a href="#Page_142">142</a>, <a href="#Page_148">148</a>, <a href="#Page_149">149</a>, <a href="#Page_151">151</a>, <a href="#Page_152">152</a>, <a href="#Page_155">155</a>, <a href="#Page_156">156</a>, <a href="#Page_173">173</a>, <a href="#Page_241">241</a>, <a href="#Page_243">243</a>, <a href="#Page_244">244</a>, <a href="#Page_246">246</a>, <a href="#Page_279">279</a>, <a href="#Page_280">280</a>, <a href="#Page_291">291</a>, <a href="#Page_294">294</a>, <a href="#Page_297">297</a>, <a href="#Page_298">298</a>, <a href="#Page_300">300</a>, <a href="#Page_311">311</a>, <a href="#Page_338">338</a>;</li> +<li class="isub1">quoted, <a href="#Page_56">56</a>, <a href="#Page_91">91</a>, <a href="#Page_97">97</a>, <a href="#Page_152">152</a>, <a href="#Page_243">243</a>, <a href="#Page_244">244</a>, <a href="#Page_297">297</a>.</li> + +<li class="indx">Weismannism, diagram of constituent theories, <a href="#Page_43">43</a>, <a href="#Page_136">136</a>;</li> +<li class="isub1">elusiveness of, <a href="#Page_334">334</a>.</li> + +<li class="indx"><i>Weismannism once more</i>, referred to, <a href="#Page_66">66</a>, <a href="#Page_95">95</a>.</li> + +<li class="indx"><span class="smcap">Welby</span>, Hon. Lady, referred to, <a href="#Page_90">90</a>.</li> + +<li class="indx"><span class="smcap">Westphal</span>, Prof., referred to, <a href="#Page_105">105</a>, <a href="#Page_107">107</a>.</li> + +<li class="indx">Withdrawal of foot by reflex action, <a href="#Page_75">75</a>.</li> + +<li class="indx"><span class="smcap">Würtenberger</span>, Dr., referred to, <a href="#Page_254">254</a>.</li> + + +<li class="ifrst">Y.</li> + +<li class="indx"><span class="smcap">Yarrell</span>, Mr., referred to, <a href="#Page_186">186</a>.</li> +</ul> + + + + +<hr class="full" /> +<h2>LIST OF OPEN COURT PUBLICATIONS +ON SCIENCE</h2> + + +<p><b>The Primary Factors of Organic Evolution.</b> By +<b>E. D. Cope</b>. Second edition. Pages, 550; illustrations, +121; tables, bibliography, and index. +Cloth, $2.00 net.</p> + +<blockquote><p>A comprehensive handbook of the Neo-Lamarckian +theory of Evolution.</p></blockquote> + + +<p><b>A Mechanico-Physiological Theory of Organic Evolution.</b> +By <b>Carl von Naegeli</b>. Translated by +V. A. Clark and F. A. Waugh. Price, cloth, 60c; +paper, 30c net.</p> + +<blockquote><p>A synopsis of his great work on evolution.</p></blockquote> + + +<p><b>Darwin and After Darwin.</b> An exposition of the +Darwinian Theory and a Discussion of Post-Darwinian +Questions. By <b>George J. Romanes</b>. +3 vols. Price, $4.00 net.</p> + +<p>Part I. The Darwinian Theory. Price, cloth, +$2.00 net.</p> + +<p>Part II. Post-Darwinian Questions: Heredity +and Utility. Price, cloth, $1.50 net.</p> + +<p>Part III. Post-Darwinian Questions. Isolation +and Physiological Selection. Price, cloth, +$1.00 net.</p> + + +<p><b>An Examination of Weismannism.</b> By <b>George J. +Romanes</b>. Price, cloth, $1.00 net; paper, 40c +net.</p> + +<blockquote><p>"The best criticism of the subject in our language."—<i>The +Outlook.</i></p></blockquote> + + +<p><b>On Germinal Selection.</b> By <b>August Weismann</b>. +Translated by T. J. McCormack. Price, paper, +30c net.</p> + + +<p><b>The Rise of Man.</b> A Sketch of the Origin of the +Human Race. By <b>Paul Carus</b>. Pages, 97; illustrated. +Boards, cloth back, 75c net.</p> + + +<p><b>The Scope and Content of the Science of Anthropology.</b> +By <b>Juul Dieserud</b>. Pages, 200; cloth, gilt +top, $2.00 net.</p> + +<blockquote><p>"The science of Anthropology," according to Topinard, +"is that branch of natural history which treats of man, and +the races of men."</p></blockquote> + + +<p><b>Experiments on the Generation of Insects.</b> By +<b>Francesco Redi</b>. Translated from the Italian +edition of 1688, by <b>Mab Bigelow</b>. Illustrated. +Cloth, $2.00 net.</p> + +<blockquote><p>This book may be counted as one of the classics of the +theory of evolution.</p></blockquote> + + +<p><b>Ants and Some Other Insects.</b> An Inquiry into the +Psychic Powers of these Animals, with an Appendix +on the peculiarities of their Olfactory +Sense. By <b>August Forel</b>. Translated by <b>William +M. Wheeler</b>. Price, $1.00 net; paper, 55c +net.</p> + + +<p><b>Plant Breeding.</b> Comments on the Experiments of +Nilsson and Burbank. By <b>Hugo de Vries</b>. +Pages, xv, 360. Illustrated with 114 half-tone +plates from nature. Printed on fine paper, in +large type. Cloth, gilt top. Price, $1.50 net.</p> + +<blockquote><p>A scientific book in simple language. Intensely interesting +as well as instructive. Of special value to every botanist, +horticulturist and farmer.</p></blockquote> + + +<p><b>Species and Varieties, Their Origin by Mutation.</b> +Lectures delivered at the University of California +by <b>Hugo de Vries</b>, Professor of Botany +in the University of Amsterdam. Pages, xviii, +847. Cloth, gilt top, $5.00 net.</p> + + +<p><b>The Mutation Theory.</b> Experiments and Observations +on the Origin of Species in the Vegetable +Kingdom. 2 vols. Numerous illustrations, colored +plates. By <b>Hugo de Vries</b>. Translated by +Prof. <b>A. B. Farmer</b> and <b>A. D. Darbishire</b>. Cloth, +per volume, $4.00.</p> + +<blockquote><p>This is de Vries' great book on a new explanation of the +evolution theory, accounting for the formation of species not +by the struggle for existence but by mutation.</p></blockquote> + + +<p><b>Intracellular Pangenesis.</b> Including a paper on Fertilization +and Hybridization. By <b>Hugo de Vries</b>. +Translated from the German by <b>C. Stuart Gager</b>. +Cloth, $3.00 net.</p> + +<blockquote><p>This is de Vries' first important book. It is not very +large, but ought to be read by all students of botany, and +also by those who are interested in the theory of evolution.</p></blockquote> + + +<p><b>On Orthogenesis and the Impotence of Natural +Selection in Species-Formation.</b> By <b>Th. Eimer</b>. +Translated by <b>T. J. McCormack</b>. Price, paper, +30c net.</p> + +<blockquote><p>Another critic of Darwin who claims that organisms +develop through transmission of acquired characters.</p></blockquote> + + +<p><b>On the Inheritance of Acquired Characters.</b> By +<b>Eugenio Rignano</b>. Translated by <b>Basil C. H. +Harvey</b>. With an Appendix "On the Mnemonic +Origin and Nature of Affective Tendencies." +Cloth, $3.00 net.</p> + +<blockquote><p>Rignano calls his theory "centro-epigenesis" and is greatly +influenced by Weismann.</p></blockquote> + + +<p><b>On Double Consciousness.</b> Studies in Experimental +Psychology. By <b>Alfred Binet</b>. Third edition. +Pages, 93. Cloth, 50c net; paper, 20c net.</p> + +<blockquote><p>"A most valuable contribution to this important subject +which none of its students can afford to leave unread."—<i>Public +Opinion.</i></p></blockquote> + + +<p><b>The Psychic Life of Micro-Organisms.</b> By <b>Alfred +Binet</b>. Authorized translation. Pages, xii, 120. +Cloth, 75c net; paper, 30c net.</p> + +<blockquote><p>"He fortifies his theory by such a wealth of exact observation +and experiments that the reader who follows his +demonstration carefully can hardly fail of conviction."—<i>New +York Tribune.</i></p></blockquote> + + +<p><b>The Psychology of Reasoning.</b> By <b>Alfred Binet</b>. +Translated from the second French edition by +<b>Adam Gowans Whyte</b>, B.Sc. Pages, 191. Cloth, +75c net; paper, 30c net.</p> + +<blockquote><p>"Like everything that Dr. Binet writes, the subject is +stated and expounded lucidly."—<i>The Lancet.</i></p></blockquote> + + +<p><b>The Diseases of Personality.</b> By <b>Théodule Ribot</b>. +Authorized translation. Fourth edition. Pages, +157. Cloth, 75c net; paper, 30c.</p> + +<blockquote><p>Contents: Introduction, Consciousness; Organic Disorders; +Affective Disorders; Diseases of the Intellect; Dissolution +of Personality.</p></blockquote> + + +<p><b>The Diseases of the Will.</b> By <b>Théodule Ribot</b>. +Authorized translation. Third edition. Pages, +vi, 121. Cloth, 75c net; paper, 30c net.</p> + +<blockquote><p>Contains chapters on impairments of the will and of +voluntary attention, the realm of caprices, and extinction of +the will.</p></blockquote> + + +<p><b>Essay on the Creative Imagination.</b> By <b>Théodule +Ribot</b>. Translated from the French by <b>A. H. N. +Baron</b>, Fellow in Clark University. Cloth, gilt +top. Pages, 357. $1.75 net.</p> + +<blockquote><p>The motor nature of the constructive imagination.</p></blockquote> + + +<p><b>The Psychology of Attention.</b> By <b>Théodule Ribot</b>, +Professor in the Collège de France and editor +of the "Revue Philosophique." Fifth and revised +edition. Authorized translation. Pages, 121. +Cloth, 75c net; paper, 30c net.</p> + +<blockquote><p>Contents: Spontaneous or Natural Attention; Voluntary +or Artificial Attention; Morbid States of Attention.</p></blockquote> + + +<p><b>The Diseases of Memory.</b> By <b>Théodule Ribot</b>. +Cloth, $1.50 net.</p> + + +<p><b>Memory. Lectures on the Specific Energies of the +Nervous System.</b> By <b>Ewald Hering</b>. Fourth +edition, containing an additional chapter on the +Theory of Nerve Activity. Cloth, $1.00 net.</p> + + +<p><b>The Analysis of Sensations and the Relation of the +Physical to the Psychical.</b> By <b>Ernst Mach</b>, +Emeritus Professor in the University of Vienna. +Translated by <b>C. M. Williams</b>. Third edition +revised and supplemented from the fifth German +edition by <b>Sydney Waterlow</b>, M.A. Pages, xvi, +380. Cuts, 37. Cloth, $1.50 net.</p> + + +<p><b>Popular Science Lectures.</b> By <b>Ernst Mach</b>, Professor +in the University of Vienna. Translated +from the German by <b>T. J. McCormack</b>. Third +edition. Pages, 415. Cloth, gilt top, $1.50 net; +paper, 60c net.</p> + +<blockquote><p>A portrayal of the methods and spirit of science, in lectures +on mechanics, sound, light, electricity, the conservation +of energy, philosophy and education.</p></blockquote> + + +<p><b>Man a Machine.</b> By <b>Julien Offray De La Mettrie</b>. +Including Frederick the Great's Eulogy on La +Mettrie and Extracts from La Mettrie's "Natural +History of the Soul." Translated, with +notes, by <b>Gertrude Carman Bussey</b>. French-English +edition. With a portrait of La Mettrie. +Pages, 226. Cloth, $2.00 net.</p> + +<blockquote><p>La Mettrie was the most extreme writer among the +earliest French materialists. His doctrine is an extension to +man of Descartes' doctrine that animals are automata.</p></blockquote> + + + + +<hr class="chap" /> +<h2>PORTRAITS</h2> + +<h3>Philosophical and Psychological Portrait Series</h3> + + +<p>Printed on large paper (11 × 14) with tint and platemark. +Many of them are reproduced from rare paintings, +engravings, or original photographs. They are suitable for +framing and hanging in public and private libraries, laboratories, +seminaries, recitation and lecture rooms, and will be +of interest to all concerned in education and general culture.</p> + + +<h4>PHILOSOPHICAL</h4> + +<p class="center"> +Pythagoras<br /> +Socrates<br /> +Plato<br /> +Aristotle<br /> +Epictetus<br /> +Thomas Aquinas<br /> +St. Augustine<br /> +Averrhoes<br /> +Duns Scotus<br /> +Giordano Bruno<br /> +Bacon<br /> +Hobbes<br /> +Descartes<br /> +Malebranche<br /> +Herbert Spencer<br /> +Schelling<br /> +Spinoza<br /> +Locke<br /> +Berkeley<br /> +Hume<br /> +Montesquieu<br /> +Voltaire<br /> +D'Alembert<br /> +Condillac<br /> +Diderot<br /> +Rousseau<br /> +Leibniz<br /> +Wolff<br /> +Kant<br /> +Fichte<br /> +Hegel<br /> +Schleiermacher<br /> +Schopenhauer<br /> +Herbart<br /> +Feuerbach<br /> +Lotze<br /> +Reid<br /> +Dugald Stewart<br /> +Sir W. Hamilton<br /> +Cousin<br /> +Comte<br /> +Rosmini<br /> +J. Stuart Mill<br /> +</p> + +<h4>PSYCHOLOGICAL</h4> + +<p class="center"> +Cabanis<br /> +Maine de Biran<br /> +Beneke<br /> +E. H. Weber<br /> +Fechner<br /> +Helmholtz<br /> +Wundt<br /> +Hering<br /> +G. T. Ladd<br /> +Aubert<br /> +Mach<br /> +Stumpf<br /> +Exner<br /> +Steinthal<br /> +Bain<br /> +Sully<br /> +Ward<br /> +C. L. Morgan<br /> +Romanes<br /> +Paul Janet<br /> +Ribot<br /> +Taine<br /> +Fouillée<br /> +Binet<br /> +G. Stanley Hall<br /> +</p> + +<h5>PRICES:</h5> + +<p>Philosophical and Psychological Portrait Series.</p> + +<blockquote><p>68 portraits on plate paper, $7.50 per set net. On Japanese +vellum, $12.50 per set net.</p></blockquote> + + +<p>Philosophical Portrait Series.</p> + +<blockquote><p>No. 100. 43 portraits on plate paper, $6.25 per set net.</p> + +<p>No. 100a. 43 portraits on Japanese vellum, $8.75 per set +net.</p> + +<p>Single portraits on American plate, 25c net.</p> + +<p>Single portraits on Japanese vellum, 35c net.</p></blockquote> + + +<p>Psychological Portrait Series.</p> + +<blockquote><p>No. 101. 25 portraits on plate paper, $3.75 net.</p> + +<p>No. 101a. 25 portraits on Japanese vellum, $5.00 net.</p> + +<p>Single portraits on American plate, 25c net.</p> + +<p>Single portraits on Japanese vellum, 35c net.</p></blockquote> + + +<p>Framing Portrait of Hugo de Vries.</p> + +<blockquote><p>Platino finish. 10" × 12", unmounted, $1.00 net.</p></blockquote> + + +<p>Framing Portrait of William James.</p> + +<blockquote><p>Printed on Japan paper. 11" × 14", $1.00.</p></blockquote> + + +<h4>Portraits of Eminent Mathematicians</h4> + +<p>Three portfolios edited by David Eugene Smith, Professor +of Mathematics in Teachers' College, Columbia University, +New York.</p> + +<p>In response to a widespread demand from those interested +in mathematics and the history of education, Professor Smith +has edited three portfolios of the portraits of some of the +most eminent of the world's contributors to the mathematical +sciences. Accompanying each portrait is a brief biographical +sketch, with occasional notes of interest concerning the artist +represented. The pictures are of a size that allows for +framing (11" × 14"), it being the hope that a new interest +in mathematics may be aroused through the decoration of +classrooms by the portraits of those who helped to create the +science.</p> + +<p>Portfolio No. 1.—Twelve great mathematicians down to +1700 A.D.: Thales, Pythagorus, Euclid, Archimedes, Leonardo +of Pisa, Cardan, Vieta, Napier, Descartes, Fermat, +Newton, Leibniz.</p> + +<p>Portfolio No. 2.—The most eminent founders and promotors +of the infinitesimal calculus: Cavallieri, Johann and +Jakob Bernoulli, Pascal, L'Hopital, Barrow, Laplace, Lagrange, +Euler, Gauss, Monge, and Niccolo Tartaglia.</p> + +<p>Portfolio No. 3—Eight portraits selected from the two +former portfolios, especially adapted for high schools and +academies, comprising portraits of</p> + +<blockquote><p>Thales—with whom began the study of scientific geometry;</p> + +<p>Pythagoras—who proved the proposition of the square +on the hypotenuse;</p> + +<p>Euclid—whose Elements of Geometry form the basis of +all modern text-books;</p> + +<p>Archimedes—whose treatment of the circle, cone, cylinder +and sphere influences our work today;</p> + +<p>Descartes—to whom we are indebted for the graphic +algebra in our high schools;</p> + +<p>Newton—who generalized the binomial theorem and invented +the calculus;</p> + +<p>Napier—who invented logarithms and contributed to +trigonometry;</p> + +<p>Pascal—who discovered the "Mystic Hexagram" at the +age of sixteen.</p></blockquote> + + +<p>Portraits of Mathematicians, Part I.</p> + +<blockquote><p>No. 102. 12 portraits on American plate paper, $3.00 net.</p> + +<p>No. 102a. 12 portraits on Japanese vellum, $5.00 net.</p> + +<p>Single portraits, American plate, 35c net.</p> + +<p>Single portraits, Japanese vellum, 50c net.</p></blockquote> + + +<p>Portraits of Mathematicians, Part II.</p> + +<blockquote><p>No. 103. 12 portraits on American plate paper, $3.00 net.</p> + +<p>No. 103a. 12 portraits on Japanese vellum, $5.00 net.</p> + +<p>Single portraits, American plate paper, 35c net.</p> + +<p>Single portraits, Japanese vellum, 50c net.</p></blockquote> + + +<p>Portraits of Mathematicians, High School Portfolio.</p> + +<blockquote><p>Eight portraits selected from the two preceding portfolios.</p> + +<p>No. 104. 8 portraits on American plate paper, $2.00 net.</p> + +<p>No. 104a. 8 portraits on Japanese vellum, $3.50 net.</p> + +<p>Single portraits, American plate paper, 35c net.</p> + +<p>Single portraits, Japanese vellum, 50c net.</p></blockquote> + + +<p><i>For Purchasers who may prefer not to frame the Portraits, +a neat Portfolio can be supplied at an extra cost of +$1.00.</i></p> + +<hr class="full" /> + +<h2>FOOTNOTES</h2> + +<div class="footnote"><p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">[1]</span></a> Part I, pp. 253-256.</p></div> + +<div class="footnote"><p><a name="Footnote_2_2" id="Footnote_2_2"></a><a href="#FNanchor_2_2"><span class="label">[2]</span></a> <i>Contributions to the Theory of Natural Selection</i>, p. 47.</p></div> + +<div class="footnote"><p><a name="Footnote_3_3" id="Footnote_3_3"></a><a href="#FNanchor_3_3"><span class="label">[3]</span></a> So far as we shall be concerned with them throughout this treatise, +the "Lamarckian factors" consist in the supposed transmission +of acquired characters, whether the latter be due to the direct influence +of external conditions of life on the one hand, or to the inherited effects of +use and disuse on the other. For the phrase "inherited effects of use and +disuse," I shall frequently employ the term "use-inheritance," which has +been coined by Mr. Platt Ball as a more convenient expression.</p></div> + +<div class="footnote"><p><a name="Footnote_4_4" id="Footnote_4_4"></a><a href="#FNanchor_4_4"><span class="label">[4]</span></a> <i>Origin of Species</i>, 6th ed. p. 8.</p></div> + +<div class="footnote"><p><a name="Footnote_5_5" id="Footnote_5_5"></a><a href="#FNanchor_5_5"><span class="label">[5]</span></a> <i>Variation</i> &c. 2nd ed. ii. p. 280.</p></div> + +<div class="footnote"><p><a name="Footnote_6_6" id="Footnote_6_6"></a><a href="#FNanchor_6_6"><span class="label">[6]</span></a> <i>Variation</i> &c. ii. p. 367.</p></div> + +<div class="footnote"><p><a name="Footnote_7_7" id="Footnote_7_7"></a><a href="#FNanchor_7_7"><span class="label">[7]</span></a> <i>Origin of Species</i>, p. 176.</p></div> + +<div class="footnote"><p><a name="Footnote_8_8" id="Footnote_8_8"></a><a href="#FNanchor_8_8"><span class="label">[8]</span></a> This, to the best of my judgement, is the fairest extract that I can +give of Mr. Wallace's most recently published opinions on the points in +question. [In particular as regards (<i>a</i>) see <i>Darwinism</i> pp. 435-6.] But +with regard to some of them, his expression of opinion is not always +consistent, as we shall find in detail later on. Besides, I am here taking +Mr. Wallace as representative of the Neo-Darwinian school, one or other +prominent member of which has given emphatic expression to each of the +above propositions.</p></div> + +<div class="footnote"><p><a name="Footnote_9_9" id="Footnote_9_9"></a><a href="#FNanchor_9_9"><span class="label">[9]</span></a> <i>Life and Letters</i>, vol. iii. pp. 72 and 75.</p></div> + +<div class="footnote"><p><a name="Footnote_10_10" id="Footnote_10_10"></a><a href="#FNanchor_10_10"><span class="label">[10]</span></a> Take, for example, the following, which is a fair epitome of the +whole:—"I believe that this is the simplest mode of stating and +explaining the law of variation; that some forms acquire something +which their parents did not possess; and that those which acquire +something additional have to pass through more numerous stages than +their ancestors; and those which lose something pass through fewer +stages than their ancestors; and these processes are expressed by the +terms 'acceleration' and 'retardation'" (<i>Origin of the Fittest</i>, pp. 125, +226, and 297). Even if this be "the simplest mode of <i>stating</i> the law +of variation," it obviously does nothing in the way of <i>explaining</i> the +law.</p></div> + +<div class="footnote"><p><a name="Footnote_11_11" id="Footnote_11_11"></a><a href="#FNanchor_11_11"><span class="label">[11]</span></a> <i>Floral Structures</i> (Internat. Sc. Ser. lxiv. 1888): <i>The Making of +Flowers</i> (Romance of Science Ser. 1891); and Linn. Soc. Papers 1893-4.</p></div> + +<div class="footnote"><p><a name="Footnote_12_12" id="Footnote_12_12"></a><a href="#FNanchor_12_12"><span class="label">[12]</span></a> "The law of correlation," and the "laws of growth," he does +recognize; and shows that they furnish an explanation of the origin +of many characters, which cannot be brought under "the law of +utility."</p></div> + +<div class="footnote"><p><a name="Footnote_13_13" id="Footnote_13_13"></a><a href="#FNanchor_13_13"><span class="label">[13]</span></a> <i>Natural Selection and Tropical Nature</i>, p. 205; 1891.</p></div> + +<div class="footnote"><p><a name="Footnote_14_14" id="Footnote_14_14"></a><a href="#FNanchor_14_14"><span class="label">[14]</span></a> <i>Ibid.</i> pp. 197-8.</p></div> + +<div class="footnote"><p><a name="Footnote_15_15" id="Footnote_15_15"></a><a href="#FNanchor_15_15"><span class="label">[15]</span></a> For an excellent discussion on the ontogeny of the child in this +connexion, see <i>Some Laws of Heredity</i>, by Mr. S. S. Buckman, pp. 290, +<i>et seq.</i> (Proc. Cotteswold Nat. Field Club, vol. x. p. 3, 1892).</p></div> + +<div class="footnote"><p><a name="Footnote_16_16" id="Footnote_16_16"></a><a href="#FNanchor_16_16"><span class="label">[16]</span></a> <i>loc. cit.</i> p. 198.</p></div> + +<div class="footnote"><p><a name="Footnote_17_17" id="Footnote_17_17"></a><a href="#FNanchor_17_17"><span class="label">[17]</span></a> For a discussion of this remarkable case, see <i>Mental Evolution in +Animals</i>, pp. 222-3. It appears to me that if Mr. Wallace's argument +from the "latent capacities of the voice of Man" is good for anything, +<i>a fortiori</i> it must be taken to prove that, in the case of the Parrot, "the +organ has been prepared in anticipation" of the amusement which the +cultivation of its latent capacities arouses in "civilized man."</p></div> + +<div class="footnote"><p><a name="Footnote_18_18" id="Footnote_18_18"></a><a href="#FNanchor_18_18"><span class="label">[18]</span></a> <i>Descent of Man</i>, 1st Ed. ch. xx. (Trans. Dev. Assoc. for Science, 1890).</p></div> + +<div class="footnote"><p><a name="Footnote_19_19" id="Footnote_19_19"></a><a href="#FNanchor_19_19"><span class="label">[19]</span></a> The late Prof. Moseley informed me that, during his voyage on the +<i>Challenger</i>, he had seen many men whose backs were well covered with +hair.—For an excellent discussion of the whole question, chiefly in the +light of embryology, see the paper by Buckman already alluded to, +pp. 280-289. Also, for an account of an extraordinary hairy race of men, +see <i>Alone with the Hairy Ainu</i>, by A. H. Savage Landor, 1893.</p></div> + +<div class="footnote"><p><a name="Footnote_20_20" id="Footnote_20_20"></a><a href="#FNanchor_20_20"><span class="label">[20]</span></a> E.g. "The special faculties we have been discussing clearly point to +the existence in man of something which he has not derived from +his animal progenitors—something which we may best refer to as +being of a spiritual essence or nature, capable of progressive development +under favourable conditions. On the hypothesis of this +spiritual nature, superadded to the animal nature of man, we are able +to understand much that is otherwise mysterious or unintelligible in +regard to him, especially the enormous influence of ideas, principles, +and beliefs over his whole life and action. Thus alone can we understand +the constancy of the martyr, the unselfishness of the philanthropist, +the devotion of the patriot, the enthusiasm of the artist, and the resolute +and persevering search of the scientific worker after nature's secrets. +Thus we may perceive that the love of truth, the delight in beauty, +the passion for justice, and the thrill of exultation with which we +hear of any act of courageous self-sacrifice, are the workings within +us of a higher nature which has not been developed by means of the +struggle for material existence." (<i>Darwinism</i>, p. 474.) I have quoted +this whole paragraph, because it is so inconsistent with the rest of +Mr. Wallace's system that a mere epitome of it might well have been +suspected of error. Given an intellectual being, howsoever produced, +and what is there "mysterious or unintelligible" in "the enormous +influence of ideas, principles, and beliefs over his whole life and +action"? Or again, if he be also a social being, what is the relevancy +of adducing "the constancy of the martyr," "the unselfishness of the +philanthropist," "the devotion of the patriot," "the love of truth," +"the passion for justice," "the thrill of exultation when we hear of any +act of courageous self-sacrifice," in evidence <i>against</i> the law of <i>utility</i>, +or in order to prove that a "nature" thus endowed has "<i>not</i> been +developed by means of the struggle for existence," when once this +struggle has been transferred from individuals to communities? The +whole passage reads like an ironical satire in favour of "Darwinism," +rather than a serious argument against it.</p></div> + +<div class="footnote"><p><a name="Footnote_21_21" id="Footnote_21_21"></a><a href="#FNanchor_21_21"><span class="label">[21]</span></a> See <i>Proc. Zool. Soc.</i> June 4, 1889, for an account of the performances +in this respect of the Chimpanzee "Sally." Also, for some remarks on +the psychology of the subject, in <i>Mental Evolution in Man</i>, p. 215. +I should like to take this opportunity of stating that, after the two +publications above referred to, this animal's instruction was continued, +and that, before her death, her "counting" extended as far as ten. +That is to say, any number of straws asked for from one to ten would +always be correctly given.</p></div> + +<div class="footnote"><p><a name="Footnote_22_22" id="Footnote_22_22"></a><a href="#FNanchor_22_22"><span class="label">[22]</span></a> In Prof. Lloyd Morgan's <i>Animal Life and Intelligence</i> there is an +admirable discussion on this subject, which has been published since the +above was written. The same has to be said of Weismann's Essay on +Music, where much that I have here said is anticipated. With the views +and arguments which Mr. Mivart has forcibly set forth I have already +dealt to the best of my ability in a work on <i>Mental Evolution in Man</i>.</p></div> + +<div class="footnote"><p><a name="Footnote_23_23" id="Footnote_23_23"></a><a href="#FNanchor_23_23"><span class="label">[23]</span></a> <i>American Naturalist</i>, xxii. pp. 201-207.</p></div> + +<div class="footnote"><p><a name="Footnote_24_24" id="Footnote_24_24"></a><a href="#FNanchor_24_24"><span class="label">[24]</span></a> It is almost needless to say that besides the works mentioned in this +chapter, many others have been added to the literature of Darwinism +since Darwin's death. But as none of these profess to contain much +that is original, I have not thought it necessary to consider any of them +in this merely general review of the period in question. In subsequent +chapters, however, allusions will be made to those among them which +I deem of most importance. +</p><p> +[Since this note was written and printed the following works have +been published to which it does not apply: <i>Animal Life and Intelligence</i>, +by Professor Lloyd Morgan; <i>The Colours of Animals</i>, by +Professor Poulton; and <i>Materials for the Study of Variation</i>, by +Mr. Bateson. All these works are of high value and importance. +Special reference should also be made to Professor Weismann's Essays.]</p></div> + +<div class="footnote"><p><a name="Footnote_25_25" id="Footnote_25_25"></a><a href="#FNanchor_25_25"><span class="label">[25]</span></a> Originally, Weismann's further assumption as to the perpetual +stability of germ-plasm, "since the first origin of sexual reproduction," +was another very important point of difference, but this has now been +withdrawn.</p></div> + +<div class="footnote"><p><a name="Footnote_26_26" id="Footnote_26_26"></a><a href="#FNanchor_26_26"><span class="label">[26]</span></a> I say "<i>mainly</i> formed anew," and "<i>for the most part</i> interrupted," +because even Darwin's theory does not, as is generally supposed, exclude +the doctrine of Continuity <i>in toto</i>.</p></div> + +<div class="footnote"><p><a name="Footnote_27_27" id="Footnote_27_27"></a><a href="#FNanchor_27_27"><span class="label">[27]</span></a> <i>Theory of Heredity</i> (Journ. Anthrop. Inst. 1875, p. 346).</p></div> + +<div class="footnote"><p><a name="Footnote_28_28" id="Footnote_28_28"></a><a href="#FNanchor_28_28"><span class="label">[28]</span></a> Mr. Platt Ball has, indeed, argued that "use-inheritance would often +be an evil," since, for example, "the condyle of the human jaw would +become larger than the body of the jaw, because as the fulcrum of the +lever it receives more pressure"; and similarly as regards many other +hypothetical cases which he mentions. (<i>The Effects of Use and Disuse</i>, +pp. 128-9 <i>et seq.</i>) But it is evident that this argument proves too much. +For if the effects of use and disuse as transmitted to progeny would be +an evil, it could only be because these effects as they occur in the parents +are an evil—and this they most certainly are not, being, on the contrary +and as a general rule, of a high order of adaptive value. Moreover, in the +race, there is a superadded agency always at work, which must effectually +prevent any undue accumulation of these effects—namely, natural +selection, which every Darwinist accepts as a controlling principle of all +or any other principles of change. Therefore, if, as first produced in +the life-time of individuals, the effects of use and disuse are not injurious, +much less can they become so if transmitted through the life-time of +species. Again, Mr. Wallace argues that, even supposing use-inheritance +to occur, its adapting work in the individual can never extend to the +race, seeing that the natural selection of fortuitous variations in the +directions required must always produce the adaptations <i>more quickly</i> +than would be possible by use-inheritance. This argument, being one +of more weight, will be dealt with in a future chapter.</p></div> + +<div class="footnote"><p><a name="Footnote_29_29" id="Footnote_29_29"></a><a href="#FNanchor_29_29"><span class="label">[29]</span></a> <i>Variation under Domestication</i>, ii. 392.</p></div> + +<div class="footnote"><p><a name="Footnote_30_30" id="Footnote_30_30"></a><a href="#FNanchor_30_30"><span class="label">[30]</span></a> In subsequent chapters, especially devoted to the question (i.e. +<a href="#Page_157">Section II</a>), the validity of this assumption will be considered on +its own merits.</p></div> + +<div class="footnote"><p><a name="Footnote_31_31" id="Footnote_31_31"></a><a href="#FNanchor_31_31"><span class="label">[31]</span></a> I say "the followers of Weismann," because Weismann himself, with +his clear perception of the requirements of experimental research, expressly +states the above considerations, with the conclusions to which they +lead. Nevertheless, he is not consistent in his utterances upon this +matter; for he frequently expresses himself to the effect, "that the <i>onus +probandi</i> rests with my opponents, and therefore they ought to bring +forward actual proofs" (<i>Essays</i>, i. p. 390). But, as above shown, the +<i>onus</i> rests as much with him as with his opponents; while, even if +his opponents are right, he elsewhere recognizes that they can bring +"actual proofs" of the fact only as a result of experiments which +must take many years to perform.</p></div> + +<div class="footnote"><p><a name="Footnote_32_32" id="Footnote_32_32"></a><a href="#FNanchor_32_32"><span class="label">[32]</span></a> <a href="#Page_333">Note A.</a></p></div> + +<div class="footnote"><p><a name="Footnote_33_33" id="Footnote_33_33"></a><a href="#FNanchor_33_33"><span class="label">[33]</span></a> For a fair and careful statement of the present balance of authoritative +opinion upon the question, see H. F. Osborn, <i>American Naturalist</i>, +1892, pp. 537-67.</p></div> + +<div class="footnote"><p><a name="Footnote_34_34" id="Footnote_34_34"></a><a href="#FNanchor_34_34"><span class="label">[34]</span></a> [The above paragraph is allowed to remain exactly as Mr. Romanes +left it. Chapters V and VI were however not completed. <i>See</i> <a href="#Page_vii">note</a> +appended to Preface. C. Ll. M.</p></div> + +<div class="footnote"><p><a name="Footnote_35_35" id="Footnote_35_35"></a><a href="#FNanchor_35_35"><span class="label">[35]</span></a> See, especially, his excellent remarks on this point, <i>Contemp. Rev.</i> +Sept. 1893.</p></div> + +<div class="footnote"><p><a name="Footnote_36_36" id="Footnote_36_36"></a><a href="#FNanchor_36_36"><span class="label">[36]</span></a> There is now an extensive literature within this region. The principal +writers are Cope, Scott and Osborn. Unfortunately, however, the +facts adduced are not crucial as test-cases between the rival theories—nearly +all of them, in fact, being equally susceptible of explanation by +either.</p></div> + +<div class="footnote"><p><a name="Footnote_37_37" id="Footnote_37_37"></a><a href="#FNanchor_37_37"><span class="label">[37]</span></a> For another and better illustration more recently published by +Mr. Spencer, see <i>The Inadequacy of Natural Selection</i>, p. 22.</p></div> + +<div class="footnote"><p><a name="Footnote_38_38" id="Footnote_38_38"></a><a href="#FNanchor_38_38"><span class="label">[38]</span></a> <i>Essays on Heredity</i>, vol. i. p. 389. +</p><p> +[For further treatment of the subject under discussion <i>see</i> Weismann, +<i>The All-sufficiency of Natural Selection</i> (Contemp. Rev. Sept. and +Oct. 1893), and <i>The Effect of External Influences upon Development</i>. +"Romanes Lecture" 1894, and Spencer, <i>Weismannism once more</i> (Cont. +Rev. Oct. 1894). C. Ll. M.]</p></div> + +<div class="footnote"><p><a name="Footnote_39_39" id="Footnote_39_39"></a><a href="#FNanchor_39_39"><span class="label">[39]</span></a> <i>Variation</i>, &c., vol. ii. p. 206.</p></div> + +<div class="footnote"><p><a name="Footnote_40_40" id="Footnote_40_40"></a><a href="#FNanchor_40_40"><span class="label">[40]</span></a> E. g. <i>Origin of Species</i>, p. 178.</p></div> + +<div class="footnote"><p><a name="Footnote_41_41" id="Footnote_41_41"></a><a href="#FNanchor_41_41"><span class="label">[41]</span></a> <i>Darwinism</i>, p. 418.</p></div> + +<div class="footnote"><p><a name="Footnote_42_42" id="Footnote_42_42"></a><a href="#FNanchor_42_42"><span class="label">[42]</span></a> <i>Nature</i>, vol. xliii. pp. 410, 557; vol. xliv. pp. 7, 29. I say +"adopted," because I had objected to his quoting the analogy of artificial +selection, and stated, as above, that the only way to meet Mr. Spencer's +"difficulty" was to deny the fact of co-adaptation as ever occurring in +any case. It then appeared that Professor Meldola agreed with me as to +this. But I do not yet understand why, if such were his view, he began +by endorsing Mr. Wallace's analogy from artificial selection—i. e. +confusing the case of co-adaptation with that of the blending of adaptations. +If any one denies the fact of co-adaptation, he cannot assist his +denial by arguing the totally different fact that adaptations may be +blended by free intercrossing; for this latter fact has never been questioned, +and has nothing to do with the one which he engaged in +disputing.</p></div> + +<div class="footnote"><p><a name="Footnote_43_43" id="Footnote_43_43"></a><a href="#FNanchor_43_43"><span class="label">[43]</span></a> It may be said, with regard to this particular reflex, that it may +perhaps be, so to speak, a mechanical accident, arising from the +contiguity of the sensory and motor roots in the cord. But as this +suggestion cannot apply to other reflexes presently to be adduced, it need +not be considered.</p></div> + +<div class="footnote"><p><a name="Footnote_44_44" id="Footnote_44_44"></a><a href="#FNanchor_44_44"><span class="label">[44]</span></a> Of course it will be observed that the question is not with regard +to the development of all the nerves and muscles concerned in this +particular process. It is as to the development of the co-ordinating +centres, which thus so delicately respond to the special stimuli furnished +by variations of angle to the horizon. And it is as inconceivable in this +case of reflex action, as it is in almost every other case of reflex action, +that the highly specialized machinery required for performing the adaptive +function can ever have had its origin in the performance of any other +function. Indeed, a noticeable peculiarity of reflex mechanisms as a class +is the highly specialized character of the functions which their highly +organized structures subserve.</p></div> + +<div class="footnote"><p><a name="Footnote_45_45" id="Footnote_45_45"></a><a href="#FNanchor_45_45"><span class="label">[45]</span></a> We meet with a closely analogous reflex mechanism in brainless +vertebrata of other kinds; but these do not furnish such good test cases, +because the possibility of natural selection cannot be so efficiently +attenuated. The perching of brainless birds, for instance, at once refers +us to the roosting of sleeping birds, where the reflex mechanism +concerned is clearly of high adaptive value. Therefore such a case is +not available as a test, although the probability is that birds have +inherited their balancing mechanisms from their sauropsidian ancestors, +where it would have been of no such adaptive importance.</p></div> + +<div class="footnote"><p><a name="Footnote_46_46" id="Footnote_46_46"></a><a href="#FNanchor_46_46"><span class="label">[46]</span></a> <i>Pflüger's Archiv</i>, Bd. xx. s. 23 (1879).</p></div> + +<div class="footnote"><p><a name="Footnote_47_47" id="Footnote_47_47"></a><a href="#FNanchor_47_47"><span class="label">[47]</span></a> <i>Brain</i>, part xlviii, pp. 516-19 (1889).—There is still better proof +of this in the case of certain rodents. For instance, observing that rats +and mice are under the necessity of very frequently scratching themselves +with their hind-feet, I tried the experiment of removing the latter from +newly-born individuals—i.e. before the animals were able to co-ordinate +their movements, and therefore before they had ever even attempted to +scratch themselves. Notwithstanding that they were thus destitute of +individual experience with regard to the benefit of scratching, they began +their scratching movements with their stumps as soon as they were +capable of executing co-ordinated movements, and afterwards continued +to do so till the end of their lives with as much vigour and frequency as +unmutilated animals. Although the stumps could not reach the seats +of irritation which were bent towards them, they used to move rapidly +in the air for a time sufficient to have given the itching part a good +scratch, had the feet been present—after which the animals would resume +their sundry other avocations with apparent satisfaction. These facts +showed the hereditary response to irritation by parasites to be so strong, +that even a whole life-time's experience of its futility made no difference +in the frequency or the vigour thereof.</p></div> + +<div class="footnote"><p><a name="Footnote_48_48" id="Footnote_48_48"></a><a href="#FNanchor_48_48"><span class="label">[48]</span></a> For details of his explanation of this particular case, for which +I particularly inquired, see <i>Mental Evolution in Animals</i>, pp. 301-2.</p></div> + +<div class="footnote"><p><a name="Footnote_49_49" id="Footnote_49_49"></a><a href="#FNanchor_49_49"><span class="label">[49]</span></a> <a href="#Page_337">Note B.</a></p></div> + +<div class="footnote"><p><a name="Footnote_50_50" id="Footnote_50_50"></a><a href="#FNanchor_50_50"><span class="label">[50]</span></a> For fuller treatment see <i>Mental Evolution in Animals</i>, pp. 274-285, +378-379, 381-383.</p></div> + +<div class="footnote"><p><a name="Footnote_51_51" id="Footnote_51_51"></a><a href="#FNanchor_51_51"><span class="label">[51]</span></a> For an excellent essay on the deleterious character of early forms of +religion from a biological point of view, see the Hon. Lady Welby, <i>An +Apparent Paradox in Mental Evolution</i> (Journ. Anthrop. Inst. May 1891).</p></div> + +<div class="footnote"><p><a name="Footnote_52_52" id="Footnote_52_52"></a><a href="#FNanchor_52_52"><span class="label">[52]</span></a> <i>Essays</i>, i. p. 93.</p></div> + +<div class="footnote"><p><a name="Footnote_53_53" id="Footnote_53_53"></a><a href="#FNanchor_53_53"><span class="label">[53]</span></a> See <i>Mental Evolution in Animals</i>, pp. 377-8.</p></div> + +<div class="footnote"><p><a name="Footnote_54_54" id="Footnote_54_54"></a><a href="#FNanchor_54_54"><span class="label">[54]</span></a> [See H. Spencer, <i>The Inadequacy of Natural Selection, A Rejoinder +to Professor Weismann</i>, Contemp. Rev. 1893; and <i>Weismannism once +more</i>, Ibid. Oct. 1894; Weismann, <i>The All-sufficiency of Natural Selection</i>, +Ibid. 1893; and <i>The Effect of External Influences upon Development</i>, +"Romanes Lecture" 1894: also <i>Neuter Insects and Lamarckism</i>, +W. Platt Ball, Natural Science, Feb. 1894, and <i>Neuter Insects and +Darwinism</i>, J. T. Cunningham, Ibid. April 1894. C. Ll. M.]</p></div> + +<div class="footnote"><p><a name="Footnote_55_55" id="Footnote_55_55"></a><a href="#FNanchor_55_55"><span class="label">[55]</span></a> <i>Variation of Plants and Animals</i>, vol. ii. p. 289.</p></div> + +<div class="footnote"><p><a name="Footnote_56_56" id="Footnote_56_56"></a><a href="#FNanchor_56_56"><span class="label">[56]</span></a> <i>Ibid.</i> p. 346.</p></div> + +<div class="footnote"><p><a name="Footnote_57_57" id="Footnote_57_57"></a><a href="#FNanchor_57_57"><span class="label">[57]</span></a> <i>Essays</i>, i. p. 90.</p></div> + +<div class="footnote"><p><a name="Footnote_58_58" id="Footnote_58_58"></a><a href="#FNanchor_58_58"><span class="label">[58]</span></a> <i>Nature</i>, vol. ix. pp. 361-2, 440-1; and vol. x. p. 164.</p></div> + +<div class="footnote"><p><a name="Footnote_59_59" id="Footnote_59_59"></a><a href="#FNanchor_59_59"><span class="label">[59]</span></a> <a href="#Page_291">Appendix I.</a></p></div> + +<div class="footnote"><p><a name="Footnote_60_60" id="Footnote_60_60"></a><a href="#FNanchor_60_60"><span class="label">[60]</span></a> For a fuller statement of Mr. Galton's theory of Heredity, and its +relation to Weismann's, see <i>An Examination of Weismannism</i>.</p></div> + +<div class="footnote"><p><a name="Footnote_61_61" id="Footnote_61_61"></a><a href="#FNanchor_61_61"><span class="label">[61]</span></a> For a fuller explanation of the important difference between the +mere cessation and the actual reversal of selection, see <a href="#Page_291">Appendix I.</a></p></div> + +<div class="footnote"><p><a name="Footnote_62_62" id="Footnote_62_62"></a><a href="#FNanchor_62_62"><span class="label">[62]</span></a> <i>Animal Life</i>, International Scientific Series, vol. xxxi.</p></div> + +<div class="footnote"><p><a name="Footnote_63_63" id="Footnote_63_63"></a><a href="#FNanchor_63_63"><span class="label">[63]</span></a> The experiments of Galton and Weismann upon this subject are +nugatory, as will be shown later on. But since the above was written +an important research has been published by Mr. Cunningham, of the +Marine Biological Association. For a full account I must refer the +reader to his forthcoming paper in the <i>Philosophical Transactions</i>. The +following is his own statement of the principal results:— +</p><p> +"A case which I have myself recently investigated experimentally +seems to me to support very strongly the theory of the inheritance of +acquired characters, I have shown that in normal flat-fishes, if the +lower side be artificially exposed to light for a long time, pigmentation +is developed on that side; but when the exposure is commenced +while the specimens are still in process of metamorphosis, when +pigment-cells are still present on the lower side, the action of light +does not prevent the disappearance of these pigment-cells. They +disappear as in individuals living under normal conditions, but after +prolonged exposure pigment-cells reappear. The first fact proves that +the disappearance of the pigment-cells from the lower side in the +metamorphosis is an hereditary character, and not a change produced in +each individual by the withdrawal of the lower side from the action +of light. On the other hand, the experiments show that the absence of +pigment-cells from the lower side throughout life is due to the fact +that light does not act upon that side, for, when it is allowed to +act, pigment-cells appear. It seems to me the only reasonable conclusion +from these facts is, that the disappearance of pigment-cells was +originally due to the absence of light, and that this change has now +become hereditary. The pigment-cells produced by the action of light +on the lower side are in all respects similar to those normally present +on the upper side of the fish. If the disappearance of the pigment-cells +were due entirely to a variation of the germ-plasm, no external influence +could cause them to reappear, and, on the other hand, if there were no +hereditary tendency, the colouration of the lower side of the flat-fish +when exposed would be rapid and complete."—<i>Natural Science</i>, +Oct. 1893.</p></div> + +<div class="footnote"><p><a name="Footnote_64_64" id="Footnote_64_64"></a><a href="#FNanchor_64_64"><span class="label">[64]</span></a> For Professor Weismann's statement of and discussion of these +results see <i>Essays</i>, vol. i. p. 313.</p></div> + +<div class="footnote"><p><a name="Footnote_65_65" id="Footnote_65_65"></a><a href="#FNanchor_65_65"><span class="label">[65]</span></a> <i>Oesterreichische medicinische Jahrbücher</i>, 1875, 179.</p></div> + +<div class="footnote"><p><a name="Footnote_66_66" id="Footnote_66_66"></a><a href="#FNanchor_66_66"><span class="label">[66]</span></a> <i>Loc. cit.</i></p></div> + +<div class="footnote"><p><a name="Footnote_67_67" id="Footnote_67_67"></a><a href="#FNanchor_67_67"><span class="label">[67]</span></a> <i>Essays</i>, vol. i. p. 315.</p></div> + +<div class="footnote"><p><a name="Footnote_68_68" id="Footnote_68_68"></a><a href="#FNanchor_68_68"><span class="label">[68]</span></a> <i>Les fonctions du Cerveau</i>, p. 102.</p></div> + +<div class="footnote"><p><a name="Footnote_69_69" id="Footnote_69_69"></a><a href="#FNanchor_69_69"><span class="label">[69]</span></a> <i>Essays</i>, vol. i. p. 82.</p></div> + +<div class="footnote"><p><a name="Footnote_70_70" id="Footnote_70_70"></a><a href="#FNanchor_70_70"><span class="label">[70]</span></a> As Weismann gives an excellent abstract of all the alleged facts up +to date (<i>Essays</i>, vol. i. pp. 319-324), it is needless for me to supply +another, further than that which I have already made from Brown-Séquard.</p></div> + +<div class="footnote"><p><a name="Footnote_71_71" id="Footnote_71_71"></a><a href="#FNanchor_71_71"><span class="label">[71]</span></a> <i>Examination of Weismannism</i>, p. 83.</p></div> + +<div class="footnote"><p><a name="Footnote_72_72" id="Footnote_72_72"></a><a href="#FNanchor_72_72"><span class="label">[72]</span></a> <i>Examination of Wiesmannism</i>, p. 93.</p></div> + +<div class="footnote"><p><a name="Footnote_73_73" id="Footnote_73_73"></a><a href="#FNanchor_73_73"><span class="label">[73]</span></a> <i>Ibid.</i> p. 153.</p></div> + +<div class="footnote"><p><a name="Footnote_74_74" id="Footnote_74_74"></a><a href="#FNanchor_74_74"><span class="label">[74]</span></a> <i>Origine des Plantes Domestiques, démontrée par la culture du Radis +Sauvage</i> (Paris, 1869).</p></div> + +<div class="footnote"><p><a name="Footnote_75_75" id="Footnote_75_75"></a><a href="#FNanchor_75_75"><span class="label">[75]</span></a> <i>Journl. Agric. Soc.</i> 1848.</p></div> + +<div class="footnote"><p><a name="Footnote_76_76" id="Footnote_76_76"></a><a href="#FNanchor_76_76"><span class="label">[76]</span></a> <i>Rev. Gén. de Bot.</i> tom. ii. p. 64.</p></div> + +<div class="footnote"><p><a name="Footnote_77_77" id="Footnote_77_77"></a><a href="#FNanchor_77_77"><span class="label">[77]</span></a> I am indebted to the Rev. G. Henslow for the references to +these cases. This and the passages which follow are quoted from his +letters to me.</p></div> + +<div class="footnote"><p><a name="Footnote_78_78" id="Footnote_78_78"></a><a href="#FNanchor_78_78"><span class="label">[78]</span></a> <i>Gardener's Chronicle</i>, May 31, 1890, p. 677.</p></div> + +<div class="footnote"><p><a name="Footnote_79_79" id="Footnote_79_79"></a><a href="#FNanchor_79_79"><span class="label">[79]</span></a> Since the above was written Professor Weismann has advanced, in +<i>The Germ-plasm</i>, a suggestion very similar to this. It is sufficient here +to remark, that nearly all the facts and considerations which ensue in +the present chapter are applicable to his suggestion, the essence of which +is anticipated in the above paragraph.</p></div> + +<div class="footnote"><p><a name="Footnote_80_80" id="Footnote_80_80"></a><a href="#FNanchor_80_80"><span class="label">[80]</span></a> It also serves to show that Weismann's newer doctrine of similar +"determinants" occurring both in the germ and in the somatic tissues +is a doctrine which cannot be applied to rebut this evidence of the +transmission of acquired characters in plants. Therefore even its +hypothetical validity as applied by him to explain the seasonal variation +of butterflies is rendered in a high degree dubious.</p></div> + +<div class="footnote"><p><a name="Footnote_81_81" id="Footnote_81_81"></a><a href="#FNanchor_81_81"><span class="label">[81]</span></a> [<i>See</i> <a href="#Page_vii">note</a> appended to Preface. C. LI. M.]</p></div> + +<div class="footnote"><p><a name="Footnote_82_82" id="Footnote_82_82"></a><a href="#FNanchor_82_82"><span class="label">[82]</span></a> <i>Proc. R. S. 1871.</i></p></div> + +<div class="footnote"><p><a name="Footnote_83_83" id="Footnote_83_83"></a><a href="#FNanchor_83_83"><span class="label">[83]</span></a> <i>Proc. R. S. 1890</i>, vol. xlviii. p. 457. It should be stated that the +authors do not here concern themselves with any theory of heredity.</p></div> + +<div class="footnote"><p><a name="Footnote_84_84" id="Footnote_84_84"></a><a href="#FNanchor_84_84"><span class="label">[84]</span></a> <i>See</i> <a href="#Page_vii">note</a> appended to Preface. C. Ll. M.</p></div> + +<div class="footnote"><p><a name="Footnote_85_85" id="Footnote_85_85"></a><a href="#FNanchor_85_85"><span class="label">[85]</span></a> E.g. "The supposed transmission of this artificially produced +disease (epilepsy) is the only definite instance which has been brought +forward in support of the transmission of acquired characters."—<i>Essays</i>, +p. 328.</p></div> + +<div class="footnote"><p><a name="Footnote_86_86" id="Footnote_86_86"></a><a href="#FNanchor_86_86"><span class="label">[86]</span></a> For a full treatment of Professor Huxley's views upon this subject, +see <a href="#Page_307">Appendix II.</a></p></div> + +<div class="footnote"><p><a name="Footnote_87_87" id="Footnote_87_87"></a><a href="#FNanchor_87_87"><span class="label">[87]</span></a> Professor Huxley's views upon this matter are quoted <i>in extenso</i> in +<a href="#Page_307">Appendix II.</a></p></div> + +<div class="footnote"><p><a name="Footnote_88_88" id="Footnote_88_88"></a><a href="#FNanchor_88_88"><span class="label">[88]</span></a> <i>Geographical Distribution of the Family Charadriidae</i>, p. 19.</p></div> + +<div class="footnote"><p><a name="Footnote_89_89" id="Footnote_89_89"></a><a href="#FNanchor_89_89"><span class="label">[89]</span></a> <i>Contributions to the Theory of Natural Selection</i>, p. 47 (1870); republished +in 1892.</p></div> + +<div class="footnote"><p><a name="Footnote_90_90" id="Footnote_90_90"></a><a href="#FNanchor_90_90"><span class="label">[90]</span></a> <i>Origin of Species</i>, p. 70: italics mine.</p></div> + +<div class="footnote"><p><a name="Footnote_91_91" id="Footnote_91_91"></a><a href="#FNanchor_91_91"><span class="label">[91]</span></a> <i>Darwinism</i>, p. 137: italics mine.</p></div> + +<div class="footnote"><p><a name="Footnote_92_92" id="Footnote_92_92"></a><a href="#FNanchor_92_92"><span class="label">[92]</span></a> <i>Origin of Species</i>, p. 72: Mr. Wallace himself quotes this passage +(<i>Darwinism</i>, p. 141); but says with regard to it "the important word +'all' is probably an oversight." In the Appendix (II), on Darwin's +views touching the doctrine of utility I adduce a number of precisely +equivalent passages, derived from all his different works on evolution, +and <i>every one of them</i> presenting "the important word 'all.'"</p></div> + +<div class="footnote"><p><a name="Footnote_93_93" id="Footnote_93_93"></a><a href="#FNanchor_93_93"><span class="label">[93]</span></a> See Introductory Chapter, p. 20.</p></div> + +<div class="footnote"><p><a name="Footnote_94_94" id="Footnote_94_94"></a><a href="#FNanchor_94_94"><span class="label">[94]</span></a> <i>Darwinism</i>, p. 138.</p></div> + +<div class="footnote"><p><a name="Footnote_95_95" id="Footnote_95_95"></a><a href="#FNanchor_95_95"><span class="label">[95]</span></a> <i>Origin of Species</i>, p. 176: italics mine, as also in the following.</p></div> + +<div class="footnote"><p><a name="Footnote_96_96" id="Footnote_96_96"></a><a href="#FNanchor_96_96"><span class="label">[96]</span></a> <i>Var.</i> vol. ii. p. 250.</p></div> + +<div class="footnote"><p><a name="Footnote_97_97" id="Footnote_97_97"></a><a href="#FNanchor_97_97"><span class="label">[97]</span></a> <i>Variation</i>, &c. vol. i. pp. 78-79.</p></div> + +<div class="footnote"><p><a name="Footnote_98_98" id="Footnote_98_98"></a><a href="#FNanchor_98_98"><span class="label">[98]</span></a> <i>Darwinism</i>, pp. 139-40.</p></div> + +<div class="footnote"><p><a name="Footnote_99_99" id="Footnote_99_99"></a><a href="#FNanchor_99_99"><span class="label">[99]</span></a> Mr. Wallace deems the concluding words "rather confident." +I was not, however, before aware that he extended his <i>a priori</i> views on +utility to domesticated varieties which are bred for the slaughter-house. +If he now means to indicate that these appendages are possibly +due to natural selection, he is surely going very far to save his +<i>a priori</i> dogma; and in the case next adduced will have to go further +still.</p></div> + +<div class="footnote"><p><a name="Footnote_100_100" id="Footnote_100_100"></a><a href="#FNanchor_100_100"><span class="label">[100]</span></a> <i>Origin of Species</i>, pp. 122-3.</p></div> + +<div class="footnote"><p><a name="Footnote_101_101" id="Footnote_101_101"></a><a href="#FNanchor_101_101"><span class="label">[101]</span></a> <i>Darwinism</i>, p. 140.</p></div> + +<div class="footnote"><p><a name="Footnote_102_102" id="Footnote_102_102"></a><a href="#FNanchor_102_102"><span class="label">[102]</span></a> In the next paragraph Mr. Wallace says that the appendages in +question "are apparently of the same nature as the 'sports' that arise +in our domesticated productions, but which, as Mr. Darwin says, +without the aid of selection would soon disappear." But I cannot +find that Mr. Darwin has made any such statement: what he does +say is, that whether or not a useless peculiarity will soon disappear +without the aid of selection depends upon the nature of the causes which +produce it. If these causes are of a merely transitory nature, the +peculiarity will also be transitory; but if the causes be constant, so will +be the result. Again, the point to be noticed about this "sport" is, +that, unlike what is usually understood by a "sport," it affects a whole +race or breed, is transmitted by sexual propagation, and has already +attained so definite a size and structure, that it can only be reasonably +accounted for by supposing the continued operation of <i>some constant</i> +cause. This cause can scarcely be correlation of growth, since closely +similar appendages are often seen in so different an animal as a +goat. Here, also, they run in breeds or strains, are strongly inherited, +and more "constant," as well as more "symmetrical" than they are +in pigs. This, at all events, is the account I have received of them +from goat-breeders in Switzerland.</p></div> + +<div class="footnote"><p><a name="Footnote_103_103" id="Footnote_103_103"></a><a href="#FNanchor_103_103"><span class="label">[103]</span></a> Darwin, <i>Variation</i>, &c., vol. i. pp. 92-4.</p></div> + +<div class="footnote"><p><a name="Footnote_104_104" id="Footnote_104_104"></a><a href="#FNanchor_104_104"><span class="label">[104]</span></a> <i>Ibid.</i> p. 94.</p></div> + +<div class="footnote"><p><a name="Footnote_105_105" id="Footnote_105_105"></a><a href="#FNanchor_105_105"><span class="label">[105]</span></a> Darwin, <i>Variation</i>, &c. vol. i. p. 94.</p></div> + +<div class="footnote"><p><a name="Footnote_106_106" id="Footnote_106_106"></a><a href="#FNanchor_106_106"><span class="label">[106]</span></a> Should it be objected that useless characters, according to my own +view of the Cessation of Selection, ought to disappear, and therefore +cannot be constant, the answer is evident. For, by hypothesis, it is only +those useless characters which were at one time useful that disappear +under this principle. Selection cannot cease unless it was previously present—i.e. +save in cases where the now useless character was originally due +to selection. Hence, in all cases where it was due to any other cause, the +useless character will persist at least as long as its originating cause +continues to operate. And even after the latter (whatever it may be) +has ceased to operate, the useless character will but slowly degenerate, +until the eventual failure of heredity causes it to disappear <i>in toto</i>—long +before which time it may very well have become a genetic, or some higher, +character.</p></div> + +<div class="footnote"><p><a name="Footnote_107_107" id="Footnote_107_107"></a><a href="#FNanchor_107_107"><span class="label">[107]</span></a> <i>Variation</i>, &c. vol. i. p. 340.</p></div> + +<div class="footnote"><p><a name="Footnote_108_108" id="Footnote_108_108"></a><a href="#FNanchor_108_108"><span class="label">[108]</span></a> <i>Variation</i>, &c. vol. ii. p. 271.</p></div> + +<div class="footnote"><p><a name="Footnote_109_109" id="Footnote_109_109"></a><a href="#FNanchor_109_109"><span class="label">[109]</span></a> Since the above paragraphs have been in type, the Rev. G. Henslow +has published his Linnaean Society papers which are mentioned in the +introductory chapter, and which deal in more detail with this subject, +especially as regards the facies of desert floras.</p></div> + +<div class="footnote"><p><a name="Footnote_110_110" id="Footnote_110_110"></a><a href="#FNanchor_110_110"><span class="label">[110]</span></a> <i>Trans. Entom. Soc.</i> 1889, part i. p. 79 <i>et seq.</i></p></div> + +<div class="footnote"><p><a name="Footnote_111_111" id="Footnote_111_111"></a><a href="#FNanchor_111_111"><span class="label">[111]</span></a> <i>Variation</i>, &c. vol. i. p. 40.</p></div> + +<div class="footnote"><p><a name="Footnote_112_112" id="Footnote_112_112"></a><a href="#FNanchor_112_112"><span class="label">[112]</span></a> <i>Variation</i>, &c. vol. i. p. 40.</p></div> + +<div class="footnote"><p><a name="Footnote_113_113" id="Footnote_113_113"></a><a href="#FNanchor_113_113"><span class="label">[113]</span></a> <i>Variation</i>, &c. vol. i. p. 120.</p></div> + +<div class="footnote"><p><a name="Footnote_114_114" id="Footnote_114_114"></a><a href="#FNanchor_114_114"><span class="label">[114]</span></a> See especially, Koch, <i>Die Raupen und Schmetterling der Wetterau</i>, +and <i>Die Schmetterling des Südwestlichen Deutschlands</i>, whose very +remarkable results of numerous and varied experiments are epitomized +by Eimer, <i>Organic Evolution</i>, Eng. Trans. pp. 147-153; also Poulton, +<i>Trans. Entom. Soc.</i> 1893.</p></div> + +<div class="footnote"><p><a name="Footnote_115_115" id="Footnote_115_115"></a><a href="#FNanchor_115_115"><span class="label">[115]</span></a> Mivart, <i>On Truth</i>, p. 378.</p></div> + +<div class="footnote"><p><a name="Footnote_116_116" id="Footnote_116_116"></a><a href="#FNanchor_116_116"><span class="label">[116]</span></a> Cockerell, <i>Nature</i>, vol. xli. p. 393.</p></div> + +<div class="footnote"><p><a name="Footnote_117_117" id="Footnote_117_117"></a><a href="#FNanchor_117_117"><span class="label">[117]</span></a> <i>Darwinism</i>, pp.[typo: period missing in scan] 296-7: italics mine.</p></div> + +<div class="footnote"><p><a name="Footnote_118_118" id="Footnote_118_118"></a><a href="#FNanchor_118_118"><span class="label">[118]</span></a> <i>Nature</i>, vol. xxxiii. p. 100.</p></div> + +<div class="footnote"><p><a name="Footnote_119_119" id="Footnote_119_119"></a><a href="#FNanchor_119_119"><span class="label">[119]</span></a> <i>Divergent Evolution through Cumulative Segregation</i>, Linn. Journ. +Zoology, vol. xx. p. 215.</p></div> + +<div class="footnote"><p><a name="Footnote_120_120" id="Footnote_120_120"></a><a href="#FNanchor_120_120"><span class="label">[120]</span></a> <i>Habit and Intelligence</i>, p. 241.</p></div> + +<div class="footnote"><p><a name="Footnote_121_121" id="Footnote_121_121"></a><a href="#FNanchor_121_121"><span class="label">[121]</span></a> Allusion may here again be made to the case of the niata cattle. +For here is a case where a very extreme variety is certainly not unstable, +nor produced in varying proportions from the parent form. Moreover, +as we have seen in the preceding chapter, this almost monstrous +variety most probably originated as an individual sport—being afterwards +maintained and multiplied for a time by artificial selection. Now, +whether or not this was the case, we can very well see that it may have +been. Hence it will serve to illustrate another possibility touching the +origin and maintenance of useless specific characters. For what is +to prevent an individual congenital variation of any kind (provided it +be not harmful) from perpetuating itself as a "varietal," and eventually, +should offspring become sufficiently numerous, a "specific character"? +There is nothing to prevent this, save panmixia, or the presence of free +intercrossing. But, as we shall see in the next division of this treatise, +there are in nature many forms of isolation. Hence, as often as a small +number of individuals may have experienced isolation in any of its forms, +opportunity for perpetuation will have been given to any congenital +variations which may happen to arise. Should any of these be pronounced +variations, it would afterwards be ranked as a specific character. +I do not myself think that this is the way in which indifferent specific +characters <i>usually</i> originate. On the contrary, I believe that their +origin is most frequently due to the influence of isolation on the average +characters of the whole population, as briefly stated in the text. But +here it seems worth while to notice this possibility of their occasionally +arising as merely individual variations, afterwards perpetuated +by any of the numerous isolating conditions which occur in nature. +For, if this can be the case with a varietal form so extreme as to border +on the monstrous, much more can it be so with such minute differences +as frequently go to constitute specific distinctions. It is the business of +species-makers to search out such distinctions, no matter how trivial, +and to record them as "specific characters." Consequently, wherever +in nature a congenital variation happens to arise, and to be perpetuated +by the force of heredity alone under any of the numerous forms of isolation +which occur in nature, there will be a case analogous to that of the +niata cattle.</p></div> + +<div class="footnote"><p><a name="Footnote_122_122" id="Footnote_122_122"></a><a href="#FNanchor_122_122"><span class="label">[122]</span></a> It is almost needless to say that by a definition as "logical" +is meant one which, while including all the differentiae of the thing +defined, excludes any qualities which that thing may share in common +with any other thing. But by definitions as "logically possible" I mean +the number of separate definitions which admit of being correctly given +of the same thing from different points of view. Thus, for instance, in +the present case, since the above has been in type the late M. Quatrefages' +posthumous work on <i>Darwin et ses Précurseurs Français</i> has +been published, and gives a long list of definitions of the term "species" +which from time to time have been enunciated by as many naturalists +of the highest standing as such (pp. 186-187). But while none of +these twenty or more definitions is logical in the sense just defined, +they all present one or other of the differentiae given by those in +the text.</p></div> + +<div class="footnote"><p><a name="Footnote_123_123" id="Footnote_123_123"></a><a href="#FNanchor_123_123"><span class="label">[123]</span></a> Darwinism, p. 167.</p></div> + +<div class="footnote"><p><a name="Footnote_124_124" id="Footnote_124_124"></a><a href="#FNanchor_124_124"><span class="label">[124]</span></a> <i>Nature</i>, Dec. 12, 1889, p. 129.</p></div> + +<div class="footnote"><p><a name="Footnote_125_125" id="Footnote_125_125"></a><a href="#FNanchor_125_125"><span class="label">[125]</span></a> <i>Darwinism</i>, p. 77.</p></div> + +<div class="footnote"><p><a name="Footnote_126_126" id="Footnote_126_126"></a><a href="#FNanchor_126_126"><span class="label">[126]</span></a> <i>Darwinism</i>, p. 77.</p></div> + +<div class="footnote"><p><a name="Footnote_127_127" id="Footnote_127_127"></a><a href="#FNanchor_127_127"><span class="label">[127]</span></a> Pascoe, <i>The Darwinian Theory of the Origin of Species</i>, 1891, +pp. 31-33, and 46.</p></div> + +<div class="footnote"><p><a name="Footnote_128_128" id="Footnote_128_128"></a><a href="#FNanchor_128_128"><span class="label">[128]</span></a> <i>Neuer Beitrag zum geologischen Beweis der Darwinischen Theorie</i>, +1873.</p></div> + +<div class="footnote"><p><a name="Footnote_129_129" id="Footnote_129_129"></a><a href="#FNanchor_129_129"><span class="label">[129]</span></a> <i>The Doctrine of Descent and Darwinism</i>, Eng. Trans. p. 102.</p></div> + +<div class="footnote"><p><a name="Footnote_130_130" id="Footnote_130_130"></a><a href="#FNanchor_130_130"><span class="label">[130]</span></a> <i>Origin of Species</i>, p. 175.</p></div> + +<div class="footnote"><p><a name="Footnote_131_131" id="Footnote_131_131"></a><a href="#FNanchor_131_131"><span class="label">[131]</span></a> <i>Ibid.</i> p. 176: italics mine.</p></div> + +<div class="footnote"><p><a name="Footnote_132_132" id="Footnote_132_132"></a><a href="#FNanchor_132_132"><span class="label">[132]</span></a> <i>Origin of Species</i>, p. 122.</p></div> + +<div class="footnote"><p><a name="Footnote_133_133" id="Footnote_133_133"></a><a href="#FNanchor_133_133"><span class="label">[133]</span></a> <i>A Manual of Dental Anatomy</i>, p. 455.</p></div> + +<div class="footnote"><p><a name="Footnote_134_134" id="Footnote_134_134"></a><a href="#FNanchor_134_134"><span class="label">[134]</span></a> It may be observed that this distinction was not propounded by +Mr. Wallace—nor, so far as I am aware, by anybody else—until he +joined issue with me on the subject of specific characters. Whether he +has always held this important distinction between specific and generic +characters, I know not; but, as originally enunciated, his doctrine of +utility as universal was subject to no such limitation: it was stated +unconditionally, as applying to all taxonomic divisions indifferently. +The words have already been quoted on page <a href="#Page_180">180</a>; and, if the reader +will turn to them, he may further observe that, prior to our discussion, +Mr. Wallace made no allowance for the principle of correlation, which, +as we have seen, furnishes so convenient a loop-hole of escape in cases +where even the argument from our ignorance of possible utility appears +absurd. In his latest work, however, he is much less sweeping in +his statements. He limits his doctrine to the case of "specific characters" +alone, and even with regard to them makes unlimited drafts upon +the principle of correlation.</p></div> + +<div class="footnote"><p><a name="Footnote_135_135" id="Footnote_135_135"></a><a href="#FNanchor_135_135"><span class="label">[135]</span></a> <i>Darwinism</i>, p. 297.</p></div> + +<div class="footnote"><p><a name="Footnote_136_136" id="Footnote_136_136"></a><a href="#FNanchor_136_136"><span class="label">[136]</span></a> <i>Darwinism</i>, pp. 292-3.</p></div> + +<div class="footnote"><p><a name="Footnote_137_137" id="Footnote_137_137"></a><a href="#FNanchor_137_137"><span class="label">[137]</span></a> Since the above was written both Mr. Gulick and Professor Lloyd +Morgan have independently noticed the contradiction.</p></div> + +<div class="footnote"><p><a name="Footnote_138_138" id="Footnote_138_138"></a><a href="#FNanchor_138_138"><span class="label">[138]</span></a> <i>Darwinism</i>, p. 302.</p></div> + +<div class="footnote"><p><a name="Footnote_139_139" id="Footnote_139_139"></a><a href="#FNanchor_139_139"><span class="label">[139]</span></a> <i>American Journal of Science</i>, Vol. XL. art. I. on <i>The Inconsistencies +of Utilitarianism as the Exclusive Theory of Organic Evolution</i>.</p></div> + +<div class="footnote"><p><a name="Footnote_140_140" id="Footnote_140_140"></a><a href="#FNanchor_140_140"><span class="label">[140]</span></a> Vol. xli. p. 438.</p></div> + +<div class="footnote"><p><a name="Footnote_141_141" id="Footnote_141_141"></a><a href="#FNanchor_141_141"><span class="label">[141]</span></a> <i>Nature</i>, vol. xli. p. 486.</p></div> + +<div class="footnote"><p><a name="Footnote_142_142" id="Footnote_142_142"></a><a href="#FNanchor_142_142"><span class="label">[142]</span></a> <i>Ibid.</i> vol. xlii. p. 52.</p></div> + +<div class="footnote"><p><a name="Footnote_143_143" id="Footnote_143_143"></a><a href="#FNanchor_143_143"><span class="label">[143]</span></a> <i>Presidential Address to the Bristol Naturalists' Society</i>, 1891.</p></div> + +<div class="footnote"><p><a name="Footnote_144_144" id="Footnote_144_144"></a><a href="#FNanchor_144_144"><span class="label">[144]</span></a> <i>Presidential Address to the Bristol Naturalists' Society</i>, 1891.</p></div> + +<div class="footnote"><p><a name="Footnote_145_145" id="Footnote_145_145"></a><a href="#FNanchor_145_145"><span class="label">[145]</span></a> <i>A Theory of Heredity</i>, Journal of Anthropological Institute, 1875. +Vol. v. p. 345.</p></div> + +<div class="footnote"><p><a name="Footnote_146_146" id="Footnote_146_146"></a><a href="#FNanchor_146_146"><span class="label">[146]</span></a> No one has supposed that the tendency need be "strong": it has +only to be persistent.</p></div> + +<div class="footnote"><p><a name="Footnote_147_147" id="Footnote_147_147"></a><a href="#FNanchor_147_147"><span class="label">[147]</span></a> Of course it must be observed that degeneration of complexity +involves also degeneration of size, so that a more correct statement +of the case would be—Why, under the cessation of selection, does an +organ of extreme complexity degenerate much more rapidly than one of +much less complexity? For example, under domestication the brains +of rabbits and ducks appear to have been reduced in some cases by +as much as 50 per cent. (Darwin, and Sir J. Crichton Browne.) But +if it is possible to attribute this effect—or part of it—to an artificial +selection of stupid animals, I give in the text an example occurring +under nature. Many other cases, however, might be given to show the +general rule, that under cessation of selection complexity of structure +degenerates more rapidly—and also more thoroughly—than size of it. +This, of course, is what Mr. Galton and I should expect, seeing that the +more complex a structure the greater are the number of points for +deterioration to invade when the structure is no longer "protected by +selection." (On the other hand, of course, this fact is opposed to the +view that degeneration of useless structures below the "birth-mean" of +the first generations, is exclusively due to the reversal of selection; for +economy of growth, deleterious effect of weight, and so forth, ought to +affect size of structure <i>much more</i> than complexity of it.) But I choose +the above case, partly because Professor Lloyd Morgan has himself +alluded to "the eyes of crustacea," and partly because Professor Ray +Lankester has maintained that the loss of these eyes in dark caves is due +to the reversal of selection, as distinguished from the cessation of it. In +view of the above parenthesis it will be seen that the point is not of +much importance in the present connexion; but it appears to me that +cessation of selection must here have had at least the larger share in the +process of atrophy. For while the economy of nutrition ought to have +removed the relatively large <i>foot-stalks</i> as rapidly as the <i>eyes</i>, I cannot +see that there is any advantage, other than the economy of nutrition, to +be gained by the rapid loss of hard-coated <i>eyes</i>, even though they have +ceased to be of use.</p></div> + +<div class="footnote"><p><a name="Footnote_148_148" id="Footnote_148_148"></a><a href="#FNanchor_148_148"><span class="label">[148]</span></a> Since the above was written Professor Weismann has transferred +this doctrine from the Protozoa to their ancestors.</p></div> + +<div class="footnote"><p><a name="Footnote_149_149" id="Footnote_149_149"></a><a href="#FNanchor_149_149"><span class="label">[149]</span></a> <i>Darwinism</i>, p. 131. He says:—"I have looked in vain in +Mr. Darwin's works for any such acknowledgement" (i.e. "that a large +proportion of specific distinctions must be conceded useless to the species +presenting them").</p></div> + +<div class="footnote"><p><a name="Footnote_150_150" id="Footnote_150_150"></a><a href="#FNanchor_150_150"><span class="label">[150]</span></a> <i>Origin of Species</i>, p. 175. Italics mine.</p></div> + +<div class="footnote"><p><a name="Footnote_151_151" id="Footnote_151_151"></a><a href="#FNanchor_151_151"><span class="label">[151]</span></a> <i>Darwinism</i>, p. 132.</p></div> + +<div class="footnote"><p><a name="Footnote_152_152" id="Footnote_152_152"></a><a href="#FNanchor_152_152"><span class="label">[152]</span></a> <i>Darwinism</i>, p. 142.</p></div> + +<div class="footnote"><p><a name="Footnote_153_153" id="Footnote_153_153"></a><a href="#FNanchor_153_153"><span class="label">[153]</span></a> <i>Life and Letters</i>, vol. iii. p. 161.</p></div> + +<div class="footnote"><p><a name="Footnote_154_154" id="Footnote_154_154"></a><a href="#FNanchor_154_154"><span class="label">[154]</span></a> <i>Life and Letters</i>, vol. iii. p. 158.</p></div> + +<div class="footnote"><p><a name="Footnote_155_155" id="Footnote_155_155"></a><a href="#FNanchor_155_155"><span class="label">[155]</span></a> It must be observed that Darwin uses this word, not as Mr. Wallace +always uses it (viz. as if correlation can only be with regard to adaptive +characters), but in the wider sense that any change in one part of an +organism—whether or not it happens to be an adaptive change—is apt +to induce changes in other parts.</p></div> + +<div class="footnote"><p><a name="Footnote_156_156" id="Footnote_156_156"></a><a href="#FNanchor_156_156"><span class="label">[156]</span></a> <i>Origin of Species</i>, pp. 157-8.</p></div> + +<div class="footnote"><p><a name="Footnote_157_157" id="Footnote_157_157"></a><a href="#FNanchor_157_157"><span class="label">[157]</span></a> <i>Ibid.</i></p></div> + +<div class="footnote"><p><a name="Footnote_158_158" id="Footnote_158_158"></a><a href="#FNanchor_158_158"><span class="label">[158]</span></a> <i>Origin of Species</i>, pp. 157-8.</p></div> + +<div class="footnote"><p><a name="Footnote_159_159" id="Footnote_159_159"></a><a href="#FNanchor_159_159"><span class="label">[159]</span></a> <i>Descent of Man</i>, p. 615.</p></div> + +<div class="footnote"><p><a name="Footnote_160_160" id="Footnote_160_160"></a><a href="#FNanchor_160_160"><span class="label">[160]</span></a> <i>Ibid.</i></p></div> + +<div class="footnote"><p><a name="Footnote_161_161" id="Footnote_161_161"></a><a href="#FNanchor_161_161"><span class="label">[161]</span></a> <i>Descent of Man</i>, pp. 159-60.</p></div> + +<div class="footnote"><p><a name="Footnote_162_162" id="Footnote_162_162"></a><a href="#FNanchor_162_162"><span class="label">[162]</span></a> <i>Descent of Man</i>, p. 176.</p></div> + +<div class="footnote"><p><a name="Footnote_163_163" id="Footnote_163_163"></a><a href="#FNanchor_163_163"><span class="label">[163]</span></a> The passage to which these remarks apply is likewise quoted, +in the same connexion as above, in my paper on <i>Physiological Selection</i>. +In criticising that paper in <i>Nature</i> (vol. xxxix. p. 127), Mr. Thiselton +Dyer says of my interpretation of this passage, "the obvious drift of this +does not relate to specific differences, but to those which are characteristic +of family." But in making this remark Mr. Dyer could not +have read the passage with sufficient care to note the points which I have +now explained.</p></div> + +<div class="footnote"><p><a name="Footnote_164_164" id="Footnote_164_164"></a><a href="#FNanchor_164_164"><span class="label">[164]</span></a> <i>Origin of Species</i>, p. 171.</p></div> + +<div class="footnote"><p><a name="Footnote_165_165" id="Footnote_165_165"></a><a href="#FNanchor_165_165"><span class="label">[165]</span></a> <i>Ibid.</i> p. 421.</p></div> + +<div class="footnote"><p><a name="Footnote_166_166" id="Footnote_166_166"></a><a href="#FNanchor_166_166"><span class="label">[166]</span></a> <i>Origin of Species</i>, pp. 372-373.</p></div> + +<div class="footnote"><p><a name="Footnote_167_167" id="Footnote_167_167"></a><a href="#FNanchor_167_167"><span class="label">[167]</span></a> Mr. Thiselton Dyer in <i>Nature</i>, <i>loc. cit.</i></p></div> + +<div class="footnote"><p><a name="Footnote_168_168" id="Footnote_168_168"></a><a href="#FNanchor_168_168"><span class="label">[168]</span></a> <i>Origin of Species</i>, p. 171.</p></div> + +<div class="footnote"><p><a name="Footnote_169_169" id="Footnote_169_169"></a><a href="#FNanchor_169_169"><span class="label">[169]</span></a> <i>Ibid.</i> p. 175.</p></div> + +<div class="footnote"><p><a name="Footnote_170_170" id="Footnote_170_170"></a><a href="#FNanchor_170_170"><span class="label">[170]</span></a> <i>Variation</i>, &c., vol. ii. p. 260.</p></div> + +<div class="footnote"><p><a name="Footnote_171_171" id="Footnote_171_171"></a><a href="#FNanchor_171_171"><span class="label">[171]</span></a> <i>Ibid.</i> vol. ii. p. 261.</p></div> + +<div class="footnote"><p><a name="Footnote_172_172" id="Footnote_172_172"></a><a href="#FNanchor_172_172"><span class="label">[172]</span></a> <i>Variation</i>, &c., vol. ii. p. 280.</p></div> + +<div class="footnote"><p><a name="Footnote_173_173" id="Footnote_173_173"></a><a href="#FNanchor_173_173"><span class="label">[173]</span></a> <i>Descent of Man</i>, pp. 473-4.</p></div> +<p> </p> + +<div class="transnote"> +<h4>Transcriber's Note</h4> + +<p>The following typographical errors were correctred.</p> + + +<div class="center"> +<table border="1" cellpadding="4" cellspacing="0" summary=""> +<tr><td align="left"><b>Page</b></td><td align="left"><b>Error</b></td><td align="left"><b>Correction</b></td></tr> +<tr><td align="left">10</td><td align="left">dicussion</td><td align="left">discussion</td></tr> +<tr><td align="left">45</td><td align="left">thoughout</td><td align="left">throughout</td></tr> +<tr><td align="left">229</td><td align="left">pyschological</td><td align="left">psychological</td></tr> +</table></div> + +<p>The following inconsistent hyphenations were changed.</p> + +<div class="center"> +<table border="1" cellpadding="4" cellspacing="0" summary=""> +<tr><td align="left"><b>Page</b></td><td align="left"><b>Original</b></td><td align="left"><b>Changed to</b></td></tr> +<tr><td align="left">34</td><td align="left">inter-crossing</td><td align="left">intercrossing</td></tr> +<tr><td align="left">46</td><td align="left">re-appear</td><td align="left">reappear</td></tr> +<tr><td align="left">123</td><td align="left">re-act</td><td align="left">react</td></tr> +<tr><td align="left">132</td><td align="left">eye-lid</td><td align="left">eyelid</td></tr> +<tr><td align="left">216</td><td align="left">lifetimes</td><td align="left">life-times</td></tr> +<tr><td align="left">217</td><td align="left">lifetime</td><td align="left">life-time</td></tr> +<tr><td align="left">317</td><td align="left">threefold</td><td align="left">three-fold</td></tr> +</table></div> + +<p>The following inconsistent hyphenations were not changed.</p> + +<ul><li>"somatoplasm" (3 instances) and "somato-plasm" (2 instances)</li> +<li>"twofold" (2) and "two-fold" (1)</li> +<li>"interaction" (1) and "inter-action" (1)</li> +<li>"supernatural" (1) and "super-natural" (1)</li></ul> + + +<p>Other changes:</p> + +<p>Page 16 Footnote 10 - double quotes around "acceleration" and +"retardation" changed to single quotes. A double quote inserted at the +end.</p> + +<p>In the Index - Entries "On Truth" and "Orang-utan, teeth of" moved from +under "M" to under "O".</p> +</div> + +<p> </p> +<hr class="pg" /> +<p>***END OF THE PROJECT GUTENBERG EBOOK DARWIN, AND AFTER DARWIN, VOLUME II (OF 3)***</p> +<p>******* This file should be named 37759-h.txt or 37759-h.zip *******</p> +<p>This and all associated files of various formats will be found in:<br /> +<a href="http://www.gutenberg.org/dirs/3/7/7/5/37759">http://www.gutenberg.org/3/7/7/5/37759</a></p> +<p>Updated editions will replace the previous one--the old editions +will be renamed.</p> + +<p>Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution.</p> + + + +<pre> +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +<a href="http://www.gutenberg.org/license">http://www.gutenberg.org/license)</a>. + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS,' WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.gutenberg.org/fundraising/pglaf. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://www.gutenberg.org/about/contact + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://www.gutenberg.org/fundraising/pglaf + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: http://www.gutenberg.org/fundraising/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + +Each eBook is in a subdirectory of the same number as the eBook's +eBook number, often in several formats including plain vanilla ASCII, +compressed (zipped), HTML and others. + +Corrected EDITIONS of our eBooks replace the old file and take over +the old filename and etext number. The replaced older file is renamed. +VERSIONS based on separate sources are treated as new eBooks receiving +new filenames and etext numbers. + +Most people start at our Web site which has the main PG search facility: + +<a href="http://www.gutenberg.org">http://www.gutenberg.org</a> + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. + +EBooks posted prior to November 2003, with eBook numbers BELOW #10000, +are filed in directories based on their release date. If you want to +download any of these eBooks directly, rather than using the regular +search system you may utilize the following addresses and just +download by the etext year. + +<a href="http://www.gutenberg.org/dirs/etext06/">http://www.gutenberg.org/dirs/etext06/</a> + + (Or /etext 05, 04, 03, 02, 01, 00, 99, + 98, 97, 96, 95, 94, 93, 92, 92, 91 or 90) + +EBooks posted since November 2003, with etext numbers OVER #10000, are +filed in a different way. The year of a release date is no longer part +of the directory path. The path is based on the etext number (which is +identical to the filename). The path to the file is made up of single +digits corresponding to all but the last digit in the filename. For +example an eBook of filename 10234 would be found at: + +http://www.gutenberg.org/dirs/1/0/2/3/10234 + +or filename 24689 would be found at: +http://www.gutenberg.org/dirs/2/4/6/8/24689 + +An alternative method of locating eBooks: +<a href="http://www.gutenberg.org/dirs/GUTINDEX.ALL">http://www.gutenberg.org/dirs/GUTINDEX.ALL</a> + +*** END: FULL LICENSE *** +</pre> +</body> +</html> diff --git a/37759-h/images/illus_002.jpg b/37759-h/images/illus_002.jpg Binary files differnew file mode 100644 index 0000000..0950d30 --- /dev/null +++ b/37759-h/images/illus_002.jpg diff --git a/37759-h/images/illus_055.png b/37759-h/images/illus_055.png Binary files differnew file mode 100644 index 0000000..21a83be --- /dev/null +++ b/37759-h/images/illus_055.png diff --git a/37759-h/images/illus_130.jpg b/37759-h/images/illus_130.jpg Binary files differnew file mode 100644 index 0000000..b832460 --- /dev/null +++ b/37759-h/images/illus_130.jpg diff --git a/37759-h/images/illus_200.jpg b/37759-h/images/illus_200.jpg Binary files differnew file mode 100644 index 0000000..9e25617 --- /dev/null +++ b/37759-h/images/illus_200.jpg diff --git a/37759-h/images/illus_204.jpg b/37759-h/images/illus_204.jpg Binary files differnew file mode 100644 index 0000000..22c4ede --- /dev/null +++ b/37759-h/images/illus_204.jpg diff --git a/37759-h/images/illus_279.jpg b/37759-h/images/illus_279.jpg Binary files differnew file mode 100644 index 0000000..16208bf --- /dev/null +++ b/37759-h/images/illus_279.jpg diff --git a/37759.txt b/37759.txt new file mode 100644 index 0000000..8079614 --- /dev/null +++ b/37759.txt @@ -0,0 +1,11467 @@ +The Project Gutenberg eBook, Darwin, and After Darwin, Volume II (of 3), +by George John Romanes + + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + + + + +Title: Darwin, and After Darwin, Volume II (of 3) + Post-Darwinian Questions: Heredity and Utility + + +Author: George John Romanes + + + +Release Date: October 15, 2011 [eBook #37759] + +Language: English + +Character set encoding: ISO-646-US (US-ASCII) + + +***START OF THE PROJECT GUTENBERG EBOOK DARWIN, AND AFTER DARWIN, VOLUME +II (OF 3)*** + + +E-text prepared by Marilynda Fraser-Cunliffe, L. N. Yaddanapudi, and the +Online Distributed Proofreading Team (http://www.pgdp.net) + + + +Note: Project Gutenberg also has an HTML version of this + file which includes the original illustrations. + See 37759-h.htm or 37759-h.zip: + (http://www.gutenberg.org/files/37759/37759-h/37759-h.htm) + or + (http://www.gutenberg.org/files/37759/37759-h.zip) + + + + + +DARWIN, AND AFTER DARWIN + +II + +Post-Darwinian Questions + +Heredity and Utility + + * * * * * + + +BY THE SAME AUTHOR. + + + DARWIN AND AFTER DARWIN. An Exposition of the Darwinian Theory and a + Discussion of Post-Darwinian Questions. + 1. THE DARWINIAN THEORY. 460 pages. 125 illustrations. Cloth, + $2.00. + 2. POST-DARWINIAN QUESTIONS. Edited by Prof. C. Lloyd Morgan. + 338 pages. Cloth, $1.50. Both volumes together, $3.00 net. + + AN EXAMINATION OF WEISMANNISM. 236 pages. Cloth, $1.00. + + THOUGHTS ON RELIGION. Edited by Charles Gore, M.A., Canon of + Westminster. Second Edition. 184 pages. Cloth, gilt top, $1.25. + + +THE OPEN COURT PUBLISHING COMPANY, +324 DEARBORN STREET, CHICAGO. + + * * * * * + + +[Illustration: Frontispiece] + + +DARWIN, AND AFTER DARWIN + +AN EXPOSITION OF THE DARWINIAN THEORY +AND A DISCUSSION OF POST-DARWINIAN QUESTIONS + +by the Late + +GEORGE JOHN ROMANES, M.A., LL.D., F.R.S. +Honorary Fellow of Gonville and Caius College, Cambridge + +II + +Post-Darwinian Questions +Heredity and Utility + +FOURTH EDITION + + + + + + + +Chicago London +The Open Court Publishing Company +1916 + +Chapter 1 Copyrighted by +The Open Court Publishing Co. +Chicago, Ill., 1895 + +Printed in the +United States of America + + + + +PREFACE + + +As its sub-title announces, the present volume is mainly devoted to a +consideration of those Post-Darwinian Theories which involve fundamental +questions of Heredity and Utility. + +As regards Heredity, I have restricted the discussion almost exclusively +to Professor Weismann's views, partly because he is at present by far +the most important writer upon this subject, and partly because his +views with regard to it raise with most distinctness the issue which +lies at the base of all Post-Darwinian speculation touching this +subject--the issue as to the inheritance or non-inheritance of acquired +characters. + +My examination of the Utility question may well seem to the general +reader needlessly elaborate; for to such a reader it can scarcely fail +to appear that the doctrine which I am assailing has been broken to +fragments long before the criticism has drawn to a close. But from my +previous experience of the hardness with which this fallacious doctrine +dies, I do not deem it safe to allow even one fragment of it to remain, +lest, hydra-like, it should re-develop into its former proportions. And +I can scarcely think that naturalists who know the growing prevalence of +the doctrine, and who may have followed the issues of previous +discussions with regard to it, will accuse me of being more over-zealous +in my attempt to make a full end thereof. + +One more remark. It is a misfortune attending the aim and scope of Part +II that they bring me into frequent discord with one or other of the +most eminent of Post-Darwinian writers--especially with Mr. Wallace. But +such is the case only because the subject-matter of this volume is +avowedly restricted to debateable topics, and because I choose those +naturalists who are deservedly held in most esteem to act spokesmen on +behalf of such Post-Darwinian views as appear to me doubtful or +erroneous. Obviously, however, differences of opinion on particular +points ought not to be taken as implying any failure on my part to +recognize the general scientific authority of these men, or any +inability to appreciate their labours in the varied fields of Biology. + +G. J. R. +CHRIST CHURCH, OXFORD. + + + + +NOTE + +Some time before his death Mr. Romanes decided to publish those sections +of his work which deal with Heredity and Utility, as a separate volume, +leaving Isolation and Physiological Selection for the third and +concluding part of _Darwin, and after Darwin_. + +Most of the matter contained in this part was already in type, but was +not finally corrected for the press. The alterations made therein are +for the most part verbal. + +Chapter IV was type-written; in it, too, no alterations of any moment +have been made. + +For Chapters V and VI there were notes and isolated paragraphs not yet +arranged. I had promised during his life to write for Mr. Romanes +Chapter V on the basis of these notes, extending it in such ways as +seemed to be desirable. In that case it would have been revised and +amended by the author and received his final sanction. Death annulled +this friendly compact; and since, had I written the chapter myself, it +could not receive that imprimatur which would have given its chief +value, I have decided to arrange the material that passed into my hands +without adding anything of importance thereto. The substance of Chapters +V and VI is therefore entirely the author's: even the phraseology is +his; the arrangement only is by another hand. + +Such parts of the Preface as more particularly refer to Isolation and +Physiological Selection are reserved for publication in Part III. A year +or more must elapse before that part will be ready for publication. + +Mr. F. Howard Collins has, as a kindly tribute to the memory of the +author, read through the proofs. Messrs. F. Darwin, F. Galton, H. +Seebohm, and others, have rendered incidental assistance. After much +search I am unable to give the references to one or two passages. + +I have allowed a too flattering reference to myself to stand, in +accordance with a particular injunction of Mr. Romanes given shortly +before that sad day on which he died, leaving many to mourn the loss of +a personal friend most bright, lovable, and generous-hearted, and +thousands to regret that the hand which had written so much for them +would write for them no more. + +C. LL. M. + +UNIVERSITY COLLEGE, BRISTOL, +_April, 1894_. + + + + +CONTENTS + + PAGE +CHAPTER I. +INTRODUCTORY: THE DARWINISM OF DARWIN AND OF THE +POST-DARWINIAN SCHOOLS 1 + +CHAPTER II. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Preliminary_) 39 + +CHAPTER III. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + A. _Indirect evidence in favour of the Inheritance of Acquired + Characters_ 60 + B. _Inherited effects of Use and of Disuse_ 95 + +CHAPTER IV. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + C. _Experimental evidence in favour of the Inheritance of Acquired + Characters_ 103 + +CHAPTER V. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Continued_) + A. and B. _Direct and Indirect Evidence in favour of the + Non-inheritance of Acquired Characters_ 133 + + C. _Experimental Evidence as to the Non-inheritance of Acquired + Characters_ 142 + +CHAPTER VI. +CHARACTERS AS HEREDITARY AND ACQUIRED (_Conclusion_) 150 + +CHAPTER VII. +CHARACTERS AS ADAPTIVE AND SPECIFIC 159 + +CHAPTER VIII. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Continued_) + I. _Climate_ 200 + II. _Food_ 217 + III. _Sexual Selection_ 219 + IV. _Isolation_ 223 + V. _Laws of Growth_ 226 + +CHAPTER IX. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Continued_) 228 + +CHAPTER X. +CHARACTERS AS ADAPTIVE AND SPECIFIC (_Concluded_) 251 + SUMMARY 274 + +APPENDIX I. ON PANMIXIA 291 + +APPENDIX II. ON CHARACTERS AS ADAPTIVE AND SPECIFIC 307 + +NOTE A TO PAGE 57 333 + +NOTE B TO PAGE 89 337 + + + + +LIST OF ILLUSTRATIONS + + PAGE + +Portrait of George John Romanes _Frontispiece_ + +Diagram of Prof. Weismann's Theories 43 + +FIG. 1. Guinea pigs, showing gangrene of ears due to injury of + restiform bodies 118 + +FIG. 2. Old Irish Pig (after Richardson) 188 + +FIG. 3. Skulls of Niata Ox and of Wild White Ox 192 + +FIG. 4. Lower teeth of Orang (after Tomes) 261 + + + + +CHAPTER I. + +INTRODUCTORY: THE DARWINISM OF DARWIN, AND OF THE POST-DARWINIAN +SCHOOLS. + + +It is desirable to open this volume of the treatise on _Darwin and after +Darwin_ by taking a brief survey of the general theory of descent, +first, as this was held by Darwin himself, and next, as it is now held +by the several divergent schools of thought which have arisen since +Darwin's death. + +The most important of the questions in debate is one which I have +already had occasion to mention, while dealing, in historical order, +with the objections that were brought against the theory of natural +selection during the life-time of Darwin[1]. Here, however, we must +consider it somewhat more in detail, and justify by quotation what was +previously said regarding the very definite nature of his utterances +upon the matter. This question is whether natural selection has been the +sole, or but the main, cause of organic evolution. + + [1] Part I, pp. 253-256. + +Must we regard survival of the fittest as the one and only principle +which has been concerned in the progressive modification of living +forms, or are we to suppose that this great and leading principle has +been assisted by other and subordinate principles, without the +co-operation of which the results, as presented in the animal and +vegetable kingdoms, could not have been effected? Now Darwin's answer to +this question was distinct and unequivocal. He stoutly resisted the +doctrine that natural selection was to be regarded as the only cause of +organic evolution. On the other hand, this opinion was--and still +continues to be--persistently maintained by Mr. Wallace; and it +constitutes the source of all the differences between his views and +those of Darwin. Moreover, up to the time of Darwin's death, Mr. Wallace +was absolutely alone in maintaining this opinion: the whole body of +scientific thought throughout the world being against him; for it was +deemed improbable that, in the enormously complex and endlessly varied +processes of organic evolution, only a single principle should be +everywhere and exclusively concerned[2]. But since Darwin's death there +has been a great revolution of biological thought in favour of Mr. +Wallace's opinion. And the reason for this revolution has been, that his +doctrine of natural selection as the sole cause of organic evolution has +received the corroborative support of Professor Weismann's theory of +heredity--which has been more or less cordially embraced by a certain +section of evolutionists, and which appears to carry the doctrine in +question as a logical corollary, so far, at all events, as adaptive +structures are concerned. + + [2] _Contributions to the Theory of Natural Selection_, p. 47. + +Now in this opening chapter we shall have to do merely with a setting +forth of Darwin's opinion: we are not considering how far that opinion +ought to be regarded as having been in any measure displaced by the +results of more recent progress. Such, then, being the only matter which +here concerns us, I will supply a few brief quotations, to show how +unequivocally Darwin has stated his views. First, we may take what he +says upon the "Lamarckian factors[3];" and next we may consider what he +says with regard to other factors, or, in general, upon natural +selection not being the sole cause of organic evolution. + + [3] So far as we shall be concerned with them throughout this + treatise, the "Lamarckian factors" consist in the supposed + transmission of acquired characters, whether the latter be due + to the direct influence of external conditions of life on the + one hand, or to the inherited effects of use and disuse on the + other. For the phrase "inherited effects of use and disuse," I + shall frequently employ the term "use-inheritance," which has + been coined by Mr. Platt Ball as a more convenient expression. + + "Changed habits produce an inherited effect, as in the period of + the flowering of plants when transported from one climate to + another. With animals the increased use or disuse of parts has had + a more marked influence[4]." + + [4] _Origin of Species_, 6th ed. p. 8. + + "There can be no doubt, from the facts given in this chapter, that + extremely slight changes in the conditions of life sometimes, + probably often, act in a definite manner on our domesticated + productions; and, as the action of changed conditions in causing + indefinite variability is accumulative, so it may be with their + definite action. Hence considerable and definite modifications of + structure probably follow from altered conditions acting during + long series of generations[5]." + + [5] _Variation_ &c. 2nd ed. ii. p. 280. + + "How, again, can we explain the inherited effects of the use and + disuse of particular organs? The domesticated duck flies less and + walks more than the wild duck, and its limb bones have become + diminished and increased in a corresponding manner in comparison + with those of the wild duck. A horse is trained to certain paces, + and the colt inherits similar consensual movements. The + domesticated rabbit becomes tame from close confinement; the dog, + intelligent from associating with man; the retriever is taught to + fetch and carry; and these mental endowments and bodily powers are + all inherited. Nothing in the whole circuit of physiology is more + wonderful. How can the use or disuse of a particular limb or of the + brain affect a small aggregate of reproductive cells, seated in a + distant part of the body, in such a manner that the being developed + from these cells inherits the characters of either one or both + parents?... In the chapters devoted to inheritance, it was shown + that a multitude of newly acquired characters, whether injurious or + beneficial, whether of the lowest or highest vital importance, are + often faithfully transmitted[6]." + + [6] _Variation_ &c. ii. p. 367. + + "When discussing special cases, Mr. Mivart passes over the effects + of the increased use and disuse of parts, which I have always + maintained to be highly important, and have treated in my + 'Variation under Domestication' at greater length than, as I + believe, any other writer[7]." + + [7] _Origin of Species_, p. 176. + +So much for the matured opinion of Darwin touching the validity of the +theory of use-inheritance. Turning now to his opinion on the question +whether or not there are yet any further factors concerned in the +process of organic evolution, I think it will be sufficient to quote a +single passage from the _Origin of Species_. The first paragraph of the +"Conclusion" is devoted to a _resume_ of his views upon this matter, and +consists of the following most emphatic words. + + "I have now recapitulated the facts and considerations which have + thoroughly convinced me that species have been modified, during a + long course of descent. This has been effected chiefly through the + natural selection of numerous successive, slight, favourable + variations; aided in an important manner by the inherited effects + of the use and disuse of parts; and in an unimportant manner, that + is in relation to adaptive structures, whether past or present, by + the direct action of external conditions, and by variations which + seem to us in our ignorance to arise spontaneously. It appears that + I formerly underrated the frequency and value of these latter forms + of variation, as leading to permanent modifications of structure + independently of natural selection. But as my conclusions have + lately been much misrepresented, and it has been stated that I + attribute the modification of species exclusively to natural + selection, I may be permitted to remark that in the first edition + of this work, and subsequently, I placed in a most conspicuous + position--namely, at the close of the Introduction--the following + words: 'I am convinced that natural selection has been the main, + but not the exclusive means of modification.' This has been of no + avail. Great is the power of steady misrepresentation; but the + history of science shows that fortunately this power does not long + endure." + +In the whole range of Darwin's writings there cannot be found a passage +so strongly worded as this: it presents the only note of bitterness in +all the thousands of pages which he has published. Therefore I do not +think it is necessary to supply any further quotations for the purpose +of proving the state of his opinion upon the point in question. But, be +it carefully noted, from this great or radical difference of opinion +between the joint originators of the theory of natural selection, all +their other differences of opinion arise; and seeing that since the +death of Darwin a large number of naturalists have gone over to the side +of Wallace, it seems desirable here to state categorically what these +other or sequent points of difference are. Without at present discussing +them, therefore, I will merely set them out in a tabular form, in order +that a clear perception may be gained of their logical connexion with +this primary point of difference. + + |_The Theory of Natural |_The theory of Natural | + |Selection according to |Selection according to | + |Darwin._ |Wallace._ | + | | | + |Natural Selection has been |Natural Selection has been | + |the main means of |the sole means of | + |modification, not excepting |modification, excepting in | + |the case of Man. |the case of Man. | + | | | + |(_a_) Therefore it is a |(_a_) Therefore it is | + |question of evidence |antecedently impossible | + |whether the Lamarckian |that the Lamarckian factors | + |factors have co-operated. |can have co-operated. | + | | | + |(_b_) Neither all species, |(_b_) Not only all species, | + |nor, _a fortiori_, all |but all specific | + |specific characters, have |characters, must | + |been due to natural |necessarily have been due | + |selection. |to natural selection. | + | | | + |(_c_) Thus the principle of |(_c_) Thus the principle of | + |Utility is not of universal |Utility must necessarily be | + |application, even where |of universal application, | + |species are concerned. |where species are | + | |concerned. | + | | | + |(_d_) Thus, also, the |(_d_) Thus, also, the | + |suggestion as to Sexual |suggestion as to Sexual | + |Selection, or any other |Selection, or of any other | + |supplementary cause of |supplementary cause of | + |modification, may be |modification, must be ruled | + |entertained; and, as in the |out; and, as in the case of | + |case of the Lamarckian |the Lamarckian factors, | + |factors, it is a question |their co-operation deemed | + |of evidence whether, or how |impossible. | + |far, they have co-operated. | | + | | | + |(_e_) No detriment arises |(_e_) The possibility--and, | + |to the theory of natural |_a fortiori_ the | + |selection as a theory of |probability--of any | + |the origin of species by |supplementary factors | + |entertaining the |cannot be entertained | + |possibility, or the |without serious detriment | + |probability, of |to the theory of natural | + |supplementary factors. |selection, as a theory of | + | |the origin of species. | + | | | + |(_f_) Cross-sterility in |(_f_) Cross-sterility in | + |species cannot possibly be |species is probably due to | + |due to natural selection. |natural selection[8]. | + + [8] This, to the best of my judgement, is the fairest extract that I + can give of Mr. Wallace's most recently published opinions on + the points in question. [In particular as regards (_a_) see + _Darwinism_ pp. 435-6.] But with regard to some of them, his + expression of opinion is not always consistent, as we shall find + in detail later on. Besides, I am here taking Mr. Wallace as + representative of the Neo-Darwinian school, one or other + prominent member of which has given emphatic expression to each + of the above propositions. + +As it will be my endeavour in the ensuing chapters to consider the +rights and the wrongs of these antithetical propositions, I may reserve +further quotations from Darwin's works, which will show that the above +is a correct epitome of his views as contrasted with those of Wallace +and the Neo-Darwinian school of Weismann. But here, where the object is +merely a statement of Darwin's theory touching the points in which it +differs from those of Wallace and Weismann, it will be sufficient to set +forth these points of difference in another and somewhat fuller form. So +far then as we are at present concerned, the following are the matters +of doctrine which have been clearly, emphatically, repeatedly, and +uniformly expressed throughout the whole range of Darwin's writings. + +1. That natural selection has been the main means of modification. + +2. That, nevertheless, it has not been the only means; but has been +supplemented or assisted by the co-operation of other causes. + +3. That the most "important" of these other causes has been the +inheritance of functionally-produced modifications (use-inheritance); +but this only because the transmission of such modifications to progeny +must always have had immediate reference to _adaptive_ ends, as +distinguished from merely useless change. + +4. That there are sundry other causes which lead to merely useless +change--in particular, "the direct action of external conditions, and +variations which seem to us in our ignorance to arise spontaneously." + +5. Hence, that the "principle of utility," far from being of universal +occurrence in the sphere of animate nature, is only of what may be +termed highly general occurrence; and, therefore, that certain other +advocates of the theory of natural selection were mistaken in +representing the universality of this principle as following by way of +necessary consequence from that theory. + +6. Cross-sterility in species cannot possibly be due to natural +selection; but everywhere arises as a result of some physiological +change having exclusive reference to the sexual system--a change which +is probably everywhere due to the same cause, although what this cause +could be Darwin was confessedly unable to suggest. + +Such, then, was the theory of evolution as held by Darwin, so far as the +points at present before us are concerned. And, it may now be added, +that the longer he lived, and the more he pondered these points, the +less exclusive was the _role_ which he assigned to natural selection, +and the more importance did he attribute to the supplementary factors +above named. This admits of being easily demonstrated by comparing +successive editions of his works; a method adopted by Mr. Herbert +Spencer in his essay on the _Factors of Organic Evolution_. + +My object in thus clearly defining Darwin's attitude regarding these +sundry points is twofold. + +In the first place, with regard to merely historical accuracy, it +appears to me undesirable that naturalists should endeavour to hide +certain parts of Darwin's teaching, and give undue prominence to others. +In the second place, it appears to me still more undesirable that this +should be done--as it usually is done--for the purpose of making it +appear that Darwin's teaching did not really differ very much from that +of Wallace and Weismann on the important points in question. I myself +believe that Darwin's judgement with regard to all these points will +eventually prove more sound and accurate than that of any of the recent +would-be improvers upon his system; but even apart from this opinion of +my own it is undesirable that Darwin's views should be misrepresented, +whether the misrepresentation be due to any unfavourable bias against +one side of his teaching, or to sheer carelessness in the reading of his +books. Yet the new school of evolutionists, to which allusion has now so +frequently been made, speak of their own modifications of Darwin's +teaching as "pure Darwinism," in contradistinction to what they call +"Lamarckism." In other words, they represent the principles of +"Darwinism" as standing in some kind of opposition to those of +"Lamarckism": the Darwinian principle of natural selection, they think, +is in itself enough to account for all the facts of adaptation in +organic nature. Therefore they are eager to dispense with the Lamarckian +principle of the inherited effects of use and disuse, together with the +direct influence of external conditions of life, and all or any other +causes of modification which either have been, or in the future may +possibly be, suggested. Now, of course, there is no reason why any one +should not hold these or any other opinions to which his own +independent study of natural science may lead him; but it appears to me +that there is the very strongest reason why any one who deviates from +the carefully formed opinions of such a man as Darwin, should above all +things be careful to be absolutely fair in his representations of them; +he should be scrupulously jealous, so to speak, of not letting it appear +that he is unjustifiably throwing over his own opinions the authority of +Darwin's name. + +But in the present case, as we have seen, not only do the Neo-Darwinians +strain the teachings of Darwin; they positively reverse those +teachings--representing as anti-Darwinian the whole of one side of +Darwin's system, and calling those who continue to accept that system in +its entirety by the name "Lamarckians." I know it is sometimes said by +members of this school, that in his utilization of Lamarckian principles +as accessory to his own, Darwin was actuated by motives of "generosity." +But a more preposterous suggestion could not well be made. We may +fearlessly challenge any one who speaks or writes in such a way, to show +any other instance where Darwin's great generosity of disposition had +the effect of influencing by one hair's breadth his still greater +loyalty to truth. Moreover, and with special regard to this particular +case, I would point out that in no one of his many allusions to, and +often lengthy discussions of, these so-called Lamarckian principles, +does he ever once introduce the name of Lamarck; while, on the other +hand, in the only places where he does so--whether in his books or in +his now published letters--he does so in order to express an almost +contemptuous dissatisfaction, and a total absence of obligation. Hence, +having regard to the "generosity" with which he always acknowledged +obligations, there can be no reasonable doubt that Darwin was not in the +smallest degree influenced by the speculative writings of Lamarck; or +that, even if Lamarck had never lived, the _Origin of Species_ would +have differed in any single particular from the form in which it now +stands. Finally, it must not be forgotten that Darwin's acceptance of +the theory of use-inheritance was vitally essential to his theory of +Pangenesis--that "beloved child" over which he had "thought so much as +to have lost all power of judging it[9]." + + [9] _Life and Letters_, vol. iii. pp. 72 and 75. + +What has just been said touching the relations between Darwin's theory +and that of Lamarck, applies with equal force to the relations between +Darwin's theory and any other theory appertaining to evolution which has +already been, or may hereafter be propounded. Yet so greatly have some +of the Neo-Darwinians misunderstood the teachings of Darwin, that they +represent as "Darwinian heresy" any suggestions in the way of factors +"supplementary to," or "co-operative with" natural selection. Of course, +if these naturalists were to avow themselves followers of Wallace, +instead of followers of Darwin, they would be perfectly justified in +repudiating any such suggestions as, _ipso facto_ heretical. But, as we +have now seen, through all his life Darwin differed from Wallace with +regard to this very point; and therefore, unlike Wallace, he was always +ready to entertain "additional suggestions" regarding the causes of +organic evolution--several of which, indeed, he himself supplied. Hence +we arrive at this curious state of matters. Those biologists who of late +years have been led by Weismann to adopt the opinions of Wallace, +represent as anti-Darwinian the opinions of other biologists who still +adhere to the unadulterated doctrines of Darwin. Weismann's _Essays on +Heredity_ (which argue that natural selection is the only possible cause +of adaptive modification) and Wallace's work on _Darwinism_ (which in +all the respects where any charge of "heresy" is concerned directly +contradicts the doctrine of Darwin)--these are the writings which are +now habitually represented by the Neo-Darwinians as setting forth the +views of Darwin in their "pure" form. The result is that, both in +conversation and in the press, we habitually meet with complete +inversions of the truth, which show the state of confusion into which a +very simple matter has been wrought by the eagerness of certain +naturalists to identify the views of Darwin with those of Wallace and +Weismann. But we may easily escape this confusion, if we remember that +wherever in the writings of these naturalists there occur such phrases +as "pure Darwinism" we are to understand pure _Wallaceism_, or the pure +theory of natural selection to the exclusion of any supplementary +theory. Therefore it is that for the sake of clearness I coined, several +years ago, the terms "Neo-Darwinian" and "Ultra-Darwinian" whereby to +designate the school in question. + + * * * * * + +So much, then, for the Darwinism of Darwin, as contrasted with the +Darwinism of Wallace, or, what is the same thing, of the Neo-Darwinian +school of Weismann. Next we may turn, by way of antithesis, to the +so-called "Neo-Lamarckian" school of the United States. For, by a +curious irony of fate, while the Neo-Darwinian school is in Europe +seeking to out-Darwin Darwin by assigning an exclusive prerogative to +natural selection in both kingdoms of animate nature, the Neo-Lamarckian +school is in America endeavouring to reform Darwinism in precisely the +opposite direction--viz. by transferring the sovereignty from natural +selection to the principles of Lamarck. Without denying to natural +selection a more or less important part in the process of organic +evolution, members of this school believe that much greater importance +ought to be assigned to the inherited effects of use and disuse than was +assigned to these agencies by Darwin. Perhaps this noteworthy state of +affairs, within a decade of Darwin's death, may lead us to anticipate +that his judgement--standing, as it does, between these two +extremes--will eventually prove the most accurate of all, with respect +to the relative importance of these factors of evolution. But, be this +as it may, I must now offer a few remarks upon the present position of +the matter. + +In the first place, to any one who (with Darwin and against Weismann) +admits not only the abstract possibility, but an actual working, of the +Lamarckian factors, it becomes difficult to determine, even +approximately, the degrees of value which ought to be ascribed to them +and to natural selection respectively. For, since the results are in +both cases identical in kind (as, adaptive changes of organic types), +where both sets of causes are supposed to be in operation together, we +have no means of estimating the relative shares which they have had in +bringing about these results. Of course there are large numbers of cases +where it cannot possibly be supposed that the Lamarckian factors have +taken any part at all in producing the observed effects; and therefore +in such cases there is almost full agreement among evolutionists in +theoretically ascribing such effects to the exclusive agency of natural +selection. Of such, for instance, are the facts of protective colouring, +of mimicry, of the growth of parts which, although _useful_, are never +_active_ (e.g. shells of mollusks, hard coverings of seeds), and so on. +But in the majority of cases where adaptive structures are concerned, +there is no means of discriminating between the influences of the +Lamarckian and the Darwinian factors. Consequently, if by the +Neo-Lamarckian school we understand all those naturalists who assign any +higher importance to the Lamarckian factors than was assigned to them by +Darwin, we may observe that members of this school differ very greatly +among themselves as to the degree of importance that ought to be +assigned. On the one hand we have, in Europe, Giard, Perrier, and Eimer, +who stand nearer to Darwin than do a number of the American +representatives--of whom the most prominent are Cope, Osborn, Packard, +Hyatt, Brooks, Ryder, and Dall. The most extreme of these is Professor +Cope, whose collection of essays entitled _The Origin of the Fittest_, +as well as his more recent and elaborate monograph on _The Development +of the Hard Parts of the Mammalia_, represent what appears even to some +other members of his school an extravagant estimate of the importance +of Lamarckian principles. + +But the most novel, and in many respects the most remarkable school of +what may be termed Anti-selectionists is one which is now (1894) rapidly +increasing both in numbers and in weight, not only in the New World, but +also in Germany, and to a lesser extent, in Great Britain. + +This school, without being either Lamarckian or Darwinian (for its +individual members differ widely from one another in these respects) +maintains a principle which it deems of more importance than either +use-inheritance or natural selection. This principle it calls +Self-adaptation. It is chiefly botanists who constitute this school, and +its principal representatives, in regard to authority, are Sachs, +Pfeffer and Henslow. + +Apart from topics which are to be dealt with in subsequent chapters, the +only matters of much importance which have been raised in the +Post-Darwinian period are those presented by the theories of Geddes, +Cope, Hyatt, and others, and certain more or less novel ideas set forth +in Wallace's _Darwinism_. + +Mr. Geddes has propounded a new theory of the origin of species, which +in his judgement supersedes to a large extent the theory of natural +selection. He has also, in conjunction with Mr. Thomson, propounded a +theory of the origin of sex. For my own part, I cannot see that these +views embody any principles or suggestions of a sufficiently definite +kind to constitute them theories at all. In this respect the views of +Mr. Geddes resemble those of Professors Cope, Hyatt, and others, on what +they term "the law of acceleration and retardation." In all these +cases, so far as I can see, the so-called explanations are not in fact +any explanations; but either a mere re-statement of the facts, or else +an enunciation of more or less meaningless propositions. Thus, when it +is said that the evolution of any given type has been due to the +"acceleration of growth-force" with respect to some structures, and the +"retardation of growth-force" with respect to others, it appears evident +that we have not any real explanation in terms of causality; we have +only the form of an explanation in the terms of a proposition. All that +has been done is to express the fact of evolution in somewhat obscure +phraseology, since the very thing we want to know about this fact +is--What are the causes of it as a fact, or the reasons which have led +to the increase of some of the parts of any given type, and the +concomitant decrease of others? It is merely the facts themselves that +are again presented by saying that the development has been in the one +case accelerated, while in the other it has been retarded[10]. + + [10] Take, for example, the following, which is a fair epitome of + the whole:--"I believe that this is the simplest mode of + stating and explaining the law of variation; that some forms + acquire something which their parents did not possess; and that + those which acquire something additional have to pass through + more numerous stages than their ancestors; and those which lose + something pass through fewer stages than their ancestors; and + these processes are expressed by the terms 'acceleration' and + 'retardation'" (_Origin of the Fittest_, pp. 125, 226, and + 297). Even if this be "the simplest mode of _stating_ the law + of variation," it obviously does nothing in the way of + _explaining_ the law. + +So much for what may be termed this New World theory of the origin of +species: it is a mere re-statement of the facts. Mr. Geddes' theory, on +the other hand, although more than a mere re-statement of the facts, +appears to me too vague to be of any explanatory service. His view is +that organic evolution has everywhere depended upon an antagonism, +within the limits of the same organism, between the processes of +nutrition and those of reproduction. But although he is thus able +hypothetically to explain certain facts--such as the shortening of a +flower-spike into a composite flower--the suggestion is obviously +inadequate to meet, even hypothetically, most of the facts of organic +evolution, and especially the development of _adaptive_ structures. +Therefore, it seems to me, we may dismiss it even as regards the +comparatively few facts which it might conceivably explain--seeing that +these same facts may be equally well explained by the causes which are +already known to operate in other cases. For it is the business of +natural selection to ensure that there shall nowhere be any needless +expenditure of vital energy, and, consequently, that everywhere the +balance between nutrition and reproduction shall be most profitably +adjusted. + +Similarly with respect to the theory of the _Origin of Sex_, I am unable +to perceive even this much of scientific relevancy. As stated by its +authors the theory is, that the female is everywhere "anabolic," as +compared with the male, which is "katabolic." By anabolic is meant +comparative inactivity of protoplasmic change due to a nutritive winding +up of molecular constitution, while by katabolic is meant the opposite +condition of comparative activity due to a dynamic running down of +molecular constitution. How, then, can the _origin_ of sex be explained, +or the _causes_ which led to the differentiation of the sexes be shown +by saying that the one sex is anabolic and the other katabolic? In so +far as these verbal statements serve to express what is said to be a +general fact--namely, that the female sexual elements are less mobile +than the male--they merely serve to re-state this general fact in +terminology which, as the authors themselves observe, is "unquestionably +ugly." But in so far as any question of _origin_ or _causality_ is +concerned, it appears to me that there is absolutely no meaning in such +statements. They belong to the order of merely formal explanations, as +when it is said that the toxic qualities of morphia are due to this drug +possessing a soporific character. + +Much the same, in my opinion, has to be said of the Rev. G. Henslow's +theory of the origin of species by what he terms "self-adaptation." +Stated briefly his view is that there is no sufficient evidence of +natural selection as a _vera causa_, while there is very abundant +evidence of adjustments occurring without it, first in individual +organisms, and next, by inheritance of acquired characters, in species. +Now, much that he says in criticism of the selection theory is of +considerable interest as such; but when we pass from the critical to the +constructive portions of his books and papers, we again meet with the +want of clearness in thought between a statement of facts in terms of a +proposition, and an explanation of them in those of causality. Indeed, I +understand from private correspondence, that Mr. Henslow himself admits +the validity of this criticism; for in answer to my questions,--"How +does Self-adaptation work in each case, and why should protoplasm be +able to _adapt itself_ into the millions of diverse mechanisms in +nature?"--he writes. "Self-adaptation does not profess to be a _vera +causa_ at all; for the true causes of variation can only be found in the +answer to your [above] questions, and I must say at once, _these +questions cannot be answered_." That is, they cannot be answered on the +hypothesis of self-adaptation, which is therefore a statement of the +facts of adaptation as distinguished from an explanation of them. +Nevertheless, two things have here to be noted. In the first place, the +statement of facts which Mr. Henslow has collected is of considerable +theoretical importance as tending to show that there are probably causes +of an internal kind (i. e. other than natural selection) which have been +largely concerned in the adaptive modification of plants. And, in the +second place, it is not quite true that the theory of self-adaptation +is, as its author says in the sentences above quoted, a mere statement +of the facts of adaptation, without any attempt at explaining their +causes. For in his published words he does attempt to do so[11]. And, +although I think his attempt is a conspicuous failure, I ought in +fairness to give examples of it. His books are almost exclusively +concerned in an application of his theory to the mechanisms of flowers +for securing their own fertilization. These mechanisms he ascribes, in +the case of entomophylous flowers, to the "thrusts," "strains," and +other "irritations" supplied to the flowers by their insect visitors, +and consequent "reactions" of the vegetable "protoplasm." But no attempt +is made to show why these "reactions" should be of an _adaptive_ kind, +so as to build up the millions of diverse and often elaborate mechanisms +in question--including not only forms and movements, but also colours, +odours, and secretions. For my own part I confess that, even granting to +an ultra-Lamarckian extent the inheritance of acquired characters, I +could conceive of "self-adaptation" alone producing all such innumerable +and diversified adjustments only after seeing, with Cardinal Newman, an +angel in every flower. Yet Mr. Henslow somewhat vehemently repudiates +any association between his theory and that of teleology. + + [11] _Floral Structures_ (Internat. Sc. Ser. lxiv. 1888): _The + Making of Flowers_ (Romance of Science Ser. 1891); and Linn. + Soc. Papers 1893-4. + +On the whole, then, I regard all the works which are here classed +together (those by Cope, Geddes, and Henslow), as resembling one another +both in their merits and defects. Their common merits lie in their +erudition and much of their criticism, while their common defects +consist on the one hand in not sufficiently distinguishing between mere +statements and real explanations of facts, and, on the other, in not +perceiving that the theories severally suggested as substitutes for that +of natural selection, even if they be granted true, could be accepted +only as co-operative factors, and by no stretch of logic as substitutes. + + * * * * * + +Turning now to Mr. Wallace's work on _Darwinism_, we have to notice, in +the first place, that its doctrine differs from "Darwinism" in regard to +the important dogma which it is the leading purpose of that work to +sustain--namely, that "the law of utility" is, to all intents and +purposes, universal, with the result that natural selection is virtually +the only cause of organic evolution. I say "to all intents and +purposes," or "virtually," because Mr. Wallace does not expressly +maintain the abstract impossibility of laws and causes other than those +of utility and natural selection; indeed, at the end of his treatise, he +quotes with approval Darwin's judgement, that "natural selection has +been the most important, but not the exclusive means of modification." +Nevertheless, as he nowhere recognizes any other law or cause of +adaptive evolution[12], he practically concludes that, on inductive or +empirical grounds, there _is_ no such other law or cause to be +entertained--until we come to the particular case of the human mind. But +even in making this one particular exception--or in representing that +some other law than that of utility, and some other cause than that of +natural selection, must have been concerned in evolving the mind of +man--he is not approximating his system to that of Darwin. On the +contrary, he is but increasing the divergence, for, of course, it was +Darwin's view that no such exception could be legitimately drawn with +respect to this particular instance. And if, as I understand must be the +case, his expressed agreement with Darwin touching natural selection not +being the only cause of adaptive evolution has reference to this point, +the quotation is singularly inapt. + + [12] "The law of correlation," and the "laws of growth," he does + recognize; and shows that they furnish an explanation of the + origin of many characters, which cannot be brought under "the + law of utility." + +Looking, then, to these serious differences between his own doctrine of +evolution--both organic and mental--and that of Darwin, I cannot think +that Mr. Wallace has chosen a suitable title for his book; because, in +view of the points just mentioned, it is unquestionable that _Darwinism_ +differs more widely from the _Origin of Species_ than does the _Origin +of Species_ from the writings of the Neo-Lamarckians. But, passing over +this merely nominal matter, a few words ought to be added on the very +material question regarding the human mind. In subsequent chapters the +more general question, or that which relates to the range of utility and +natural selection elsewhere will be fully considered. + +Mr. Wallace says,-- + + "The immense interest that attaches to the origin of the human + race, and the amount of misconception which prevails regarding the + essential teachings of Darwin's theory on the question, as well as + regarding my own special views upon it, induce me to devote a final + chapter to its discussion." + +Now I am not aware that there is any misconception in any quarter as to +the essential teachings of Darwin's theory on this question. Surely it +is rather the case that there is a very general and very complete +understanding on this point, both by the friends and the foes of +Darwin's theory--so much so, indeed, that it is about the only point of +similar import in all Darwin's writings of which this can be said. Mr. +Wallace's "special views" on the other hand are, briefly stated, that +certain features, both of the morphology and the psychology of man, are +inexplicable by natural selection--or indeed by any other cause of the +kind ordinarily understood by the term natural: they can be explained +only by supposing "the intervention of some distinct individual +intelligence," which, however, need not necessarily be "one Supreme +Intelligence," but some other order of Personality standing anywhere in +"an infinite chasm between man and the Great Mind of the universe[13]." +Let us consider separately the corporeal and the mental peculiarities +which are given as justifying this important conclusion. + + [13] _Natural Selection and Tropical Nature_, p. 205; 1891. + +The bodily peculiarities are the feet, the hands, the brain, the voice, +and the naked skin. + +As regards the feet Mr. Wallace writes, "It is difficult to see why the +prehensile power [of the great toe] should have been taken away," +because, although "it may not be compatible with perfectly easy erect +locomotion," "how can we conceive that early man, _as an animal_, gained +anything by purely erect locomotion[14]?" But surely it is not difficult +to conceive this. In the proportion that our simian progenitors ceased +to be arboreal in their habits (and there may well have been very good +utilitarian reasons for such a change of habitat, analogous to those +which are known to have occurred in the phylogenesis of countless other +animals), it would clearly have been of advantage to them that their +already semi-erect attitude should have been rendered more and more +erect. To name one among several probabilities, the more erect the +attitude, and the more habitually it was assumed, the more would the +hands have been liberated for all the important purposes of +manipulation. The principle of the physiological division of labour +would thus have come more and more into play: natural selection would +therefore have rendered the upper extremities more and more suited to +the execution of these purposes, while at the same time it would have +more and more adapted the lower ones to discharging the sole function of +locomotion. For my own part, I cannot perceive any difficulty about +this: in fact, there is an admirable repetition of the process in the +ontogeny of our own children[15]. + + [14] _Ibid._ pp. 197-8. + + [15] For an excellent discussion on the ontogeny of the child in + this connexion, see _Some Laws of Heredity_, by Mr. S. S. + Buckman, pp. 290, _et seq._ (Proc. Cotteswold Nat. Field Club, + vol. x. p. 3, 1892). + +Next, with regard to the hand, Mr. Wallace says, that it "contains +latent capacities which are unused by savages, and must have been even +less used by palaeolithic man and his still ruder predecessors." Thus, +"it has all the appearance of an organ prepared for the use of civilized +man[16]." Even if this be true, however, it would surely be a dangerous +argument to rely upon, seeing that we cannot say of how much importance +it may have been for early man--or even apes--to have had their power of +manipulation progressively improved. But is the statement true? It +appears to me that if Mr. Wallace had endeavoured to imitate the +manufactures that were practised by "palaeolithic man," he would have +found the very best of reasons for cancelling his statement. For it is +an extremely difficult thing to chip a flint into the form of an +arrow-head: when made, the suitable attachment of it to a previously +prepared arrow is no easy matter: neither a bow nor a bow-string could +have been constructed by hands of much less perfection than our own: and +the slaying of game with the whole apparatus, when it has been +constructed, requires a manual dexterity which we may be perfectly +certain that Mr. Wallace--unless he has practised the art from +boyhood--does not possess. + + [16] _loc. cit._ p. 198. + +So it is with his similar argument that the human voice is more +"powerful," more "flexible," and presents a greater "range" and +"sweetness" than the needs of savage life can be held to require. The +futility of this argument is self-evident as regards "power." And +although its weakness is not so obvious with respect to the other three +qualities which are named, need we go further than the closely analogous +case of certain birds to show the precariousness of arguing from such +facts of organic nature to the special operation of "a superior +intelligence"? I can hardly suppose that Mr. Wallace will invoke any +such agency for the purpose of explaining the "latent capacities" of the +voice of a parrot. Yet, in many respects, these are even more wonderful +than those of the human voice, albeit in a wild state they are "never +required or used[17]." + + [17] For a discussion of this remarkable case, see _Mental Evolution + in Animals_, pp. 222-3. It appears to me that if Mr. Wallace's + argument from the "latent capacities of the voice of Man" is + good for anything, _a fortiori_ it must be taken to prove that, + in the case of the Parrot, "the organ has been prepared in + anticipation" of the amusement which the cultivation of its + latent capacities arouses in "civilized man." + +Once more, with regard to the naked skin, it seems sufficient to quote +the following passage from the first edition of the _Descent of Man_. + + "The Rev. T. R. Stebbing, in commenting on this view, remarks, that + had Mr. Wallace 'employed his usual ingenuity on the question of + man's hairless skin, he might have seen the possibility of its + selection through its superior beauty, or the health attaching to + superior cleanliness. At any rate it is surprising that he should + picture to himself a superior intelligence plucking the hair from + the backs of savage men (to whom, according to his own account, it + would have been useful and beneficial), in order that the + descendants of the poor shorn wretches might, after many deaths + from cold and damp in the course of many generations,' have been + forced to raise themselves in the scale of civilization through the + practice of various arts, in the manner indicated by Mr. + Wallace[18]." + + [18] _Descent of Man_, 1st Ed. ch. xx. (Trans. Dev. Assoc. for + Science, 1890). + +To this it may be added that the Chimpanzee "Sally" was largely denuded +of hair, especially on the back, or the part of "man's organization" on +which Mr. Wallace lays special stress, as being in this respect out of +analogy with other mammalia[19]. + + [19] The late Prof. Moseley informed me that, during his voyage on + the _Challenger_, he had seen many men whose backs were well + covered with hair.--For an excellent discussion of the whole + question, chiefly in the light of embryology, see the paper by + Buckman already alluded to, pp. 280-289. Also, for an account + of an extraordinary hairy race of men, see _Alone with the + Hairy Ainu_, by A. H. Savage Landor, 1893. + +Lastly, touching his statement that the brain of savage man is both +quantitatively and qualitatively in advance of his requirements, it is +here also sufficient to refer to Darwin's answer, as given in the +_Descent of Man_. Mr. Wallace, indeed, ignores this answer in his recent +re-publication of the argument; but it is impossible to understand why +he should have done so. To me, at all events, it seems that one out of +several considerations which Darwin advances is alone sufficient to show +the futility of this argument. I allude to the consideration that the +power of forming abstract ideas with the complex machinery of language +as the vehicle of their expression, is probably of itself enough to +account for both the mass and the structure of a savage's brain. But +this leads us to the second division of Mr. Wallace's argument, or that +derived from the mental endowments of mankind. + +Here the peculiarities called into evidence are, "the Mathematical +Faculty," "the Artistic Faculties," and "the Moral Sense." With regard +to the latter, he avows himself a member of the intuitional school of +ethics; but does not prove a very powerful advocate as against the +utilitarian[20]. + + [20] E.g. "The special faculties we have been discussing clearly + point to the existence in man of something which he has not + derived from his animal progenitors--something which we may + best refer to as being of a spiritual essence or nature, + capable of progressive development under favourable conditions. + On the hypothesis of this spiritual nature, superadded to the + animal nature of man, we are able to understand much that is + otherwise mysterious or unintelligible in regard to him, + especially the enormous influence of ideas, principles, and + beliefs over his whole life and action. Thus alone can we + understand the constancy of the martyr, the unselfishness of + the philanthropist, the devotion of the patriot, the enthusiasm + of the artist, and the resolute and persevering search of the + scientific worker after nature's secrets. Thus we may perceive + that the love of truth, the delight in beauty, the passion for + justice, and the thrill of exultation with which we hear of any + act of courageous self-sacrifice, are the workings within us of + a higher nature which has not been developed by means of the + struggle for material existence." (_Darwinism_, p. 474.) I have + quoted this whole paragraph, because it is so inconsistent with + the rest of Mr. Wallace's system that a mere epitome of it + might well have been suspected of error. Given an intellectual + being, howsoever produced, and what is there "mysterious or + unintelligible" in "the enormous influence of ideas, + principles, and beliefs over his whole life and action"? Or + again, if he be also a social being, what is the relevancy of + adducing "the constancy of the martyr," "the unselfishness of + the philanthropist," "the devotion of the patriot," "the love + of truth," "the passion for justice," "the thrill of exultation + when we hear of any act of courageous self-sacrifice," in + evidence _against_ the law of _utility_, or in order to prove + that a "nature" thus endowed has "_not_ been developed by means + of the struggle for existence," when once this struggle has + been transferred from individuals to communities? The whole + passage reads like an ironical satire in favour of "Darwinism," + rather than a serious argument against it. + +It comes, then, to this. According to Mr. Wallace's eventual +conclusion, man is to be separated from the rest of organic nature, and +the steady progress of evolution by natural causes is to be regarded as +stopped at its final stage, because the human mind presents the +faculties of mathematical calculation and aesthetic perception. Surely, +on antecedent grounds alone, it must be apparent that there is here no +kind of proportion between the conclusion and the _data_ from which it +is drawn. That we are not confined to any such grounds, I will now try +to show. + +Let it be remembered, however, that in the following brief criticism I +am not concerned with the issue as to whether, or how far, the +"faculties" in question have owed their origin or their development to +_natural selection_. I am concerned only with the doctrine that in order +to account for such and such particular "faculty" of the human mind, +some order of causation must be supposed other than what we call +natural. I am not a Neo-Darwinist, and so have no desire to make +"natural selection" synonymous with "natural causation" throughout the +whole domain of life and of mind. And I quite agree with Mr. Wallace +that, at any rate, the "aesthetic faculty" cannot conceivably have been +produced by natural selection--seeing that it is of no conceivable +life-serving value in any of the stages of its growth. Moreover, it +appears to me that the same thing has to be said of the play instincts, +sense of the ludicrous, and sundry other "faculties" of mind among the +lower animals. It being thus understood that I am not differing from Mr. +Wallace where he imposes "limits" on the powers of natural selection, +but only where he seems to take for granted that this is the same thing +as imposing limits on the powers of natural causation, my criticism is +as follows. + +In the first place, it is a psychological fallacy to regard the +so-called "faculties" of mind as analogous to "organs" of the body. To +classify the latter with reference to the functions which they severally +perform is to follow a natural method of classification. But it is an +artificial method which seeks to partition mental _faculty_ into this, +that, and the other mental _faculties_. Like all other purely artificial +classifications, this one has its practical uses; but, also like them, +it is destitute of philosophical meaning. This statement is so well +recognized by psychologists, that there is no occasion to justify it. +But I must remark that any cogency which Mr. Wallace's argument may +appear to present, arises from his not having recognized the fact which +the statement conveys. For, had he considered the mind as a whole, +instead of having contemplated it under the artificial categories of +constituent "faculties," he would probably not have laid any such +special stress upon some of the latter. In other words, he would have +seen that the general development of the human mind as a whole has +presumably involved the growth of those conventionally abstracted parts, +which he regards as really separate endowments. Or, if he should find it +easier to retain the terms of his metaphor, we may answer him by saying +that the "faculties" of mind are "correlated," like "organs" of the +body; and, therefore, that any general development of the various other +"faculties" have presumably entailed a collateral development of the two +in question. + +Again, in the second place, it would seem that Mr. Wallace has not +sufficiently considered the co-operation of either well-known natural +causes, which must have materially assisted the survival of the fittest +where these two "faculties" are concerned. For, even if we disregard the +inherited effects of use--which, however, if entertained as possible in +any degree at all, must have here constituted an important +factor,--there remain on the one hand, the unquestionable influences of +individual education and, on the other hand, of the selection principle +operating in the mind itself. + +Taking these two points separately, it is surely sufficiently well known +that individual education--or special training, whether of mind or +body--usually raises congenital powers of any kind to a more or less +considerable level above those of the normal type. In other words, +whatever doubt there may be touching the _inherited_ effects of use, +there can be no question touching the immense _developmental_ effects +thereof in the individual life-time. Now, the conditions of savage life +are not such as lead to any deliberate cultivation of the "faculties" +either of the mathematical or aesthetic order. Consequently, as might be +expected, we find both of them in what Mr. Wallace regards as but a +"latent" stage of development. But in just the same way do we find that +the marvellous powers of an acrobat when specially trained from +childhood--say to curve his spine backwards until his teeth can bite his +heels--are "latent" in all men. Or, more correctly, they are _potential +in every child_. So it is with the prodigious muscular development of a +trained athlete, and with any number of other cases where either the +body or the mind is concerned. Why then should Mr. Wallace select the +particular instances of the mathematical and aesthetic powers in savages +as in any special sense "prophetic" of future development in trained +members of civilized races? Although it is true that these "latent +capacities and powers are unused by savages," is it not equally true +that savages fail to use their latent capacities and powers as tumblers +and athletes? Moreover, is it not likewise true that _as_ used by +savages, or as occurring normally in man, such capacities and powers are +no less poorly developed than are those of the "faculties" on which Mr. +Wallace lays so much stress? In other words, are not "latent capacities +and powers" of all kinds more or less equally in excess of anything that +is ever required of them by man in a state of nature? Therefore, if we +say that where mathematics and the fine arts are concerned the potential +capacities of savage man are in some mystical sense "prophetic" of a +Newton or a Beethoven, so in consistency ought we to say that in these +same capacities we discern a similar prophecy of those other uses of +civilized life which we have in a rope-dancer or a clown. + +Again, and in addition to this, it should be remembered that, even if we +do suppose any prophecy of this kind where the particular capacities in +question are concerned, we must clearly extend the reference to the +lower animals. Not a few birds display aesthetic feelings in a measure +fairly comparable with those of savages; while we know that some animals +present the germs of a "faculty" of computation[21]. But, it is +needless to add, this fact is fatal to Mr. Wallace's argument as I +understand it--viz. that the "faculties" in question have been in some +special manner communicated by some superior intelligence to _man_. + + [21] See _Proc. Zool. Soc._ June 4, 1889, for an account of the + performances in this respect of the Chimpanzee "Sally." Also, + for some remarks on the psychology of the subject, in _Mental + Evolution in Man_, p. 215. I should like to take this + opportunity of stating that, after the two publications above + referred to, this animal's instruction was continued, and that, + before her death, her "counting" extended as far as ten. That + is to say, any number of straws asked for from one to ten would + always be correctly given. + +Once more, it is obviously unfair to select such men as a "Newton, a La +Place, a Gauss, or a Cayley" for the purpose of estimating the +difference between savages and civilized man in regard to the latter +"faculty." These men are the picked mathematicians of centuries. +Therefore they are men who not only enjoyed all the highest possible +benefits of individual culture, but likewise those who have been most +endowed with mathematical power congenitally. So to speak, they are the +best variations in this particular direction which our race is known to +have produced. But had such variations arisen among savages it is +sufficiently obvious that they could have come to nothing. Therefore, it +is the _normal average_ of "mathematical faculty" in civilized man that +should be contrasted with that of savage man; and, when due regard is +paid to the all-important consideration which immediately follows, I +cannot feel that the contrast presents any difficulty to the theory of +human evolution by natural causation. + +Lastly, the consideration just alluded to is, that civilized man enjoys +an advantage over savage man far in advance even of those which arise +from a settled state of society, incentives to intellectual training, +and so on. This inestimable advantage consists in the art of writing, +_and the consequent transmission of the effects of culture from +generation to generation_. Quite apart from any question as to the +hereditary transmission of acquired characters, we have in this +_intellectual_ transmission of acquired _experience_ a means of +accumulative cultivation quite beyond our powers to estimate. For, +unlike all other cases where we recognize the great influence of +individual use or practice in augmenting congenital "faculties" (such as +in the athlete, pianist, &c.), in this case the effects of special +cultivation do not end with the individual life, but are carried on and +on through successive generations _ad infinitum_. Hence, a civilized man +inherits mentally, if not physically, the effects of culture for ages +past, and this in whatever direction he may choose to profit therefrom. +Moreover--and I deem this an immensely important addition--in this +unique department of purely intellectual transmission, a kind of +non-physical natural selection is perpetually engaged in producing the +best results. For here a struggle for existence is constantly taking +place among "ideas," "methods," and so forth, in what may be termed a +psychological environment. The less fit are superseded by the more fit, +and this not only in the mind of the individual, but, through language +and literature, still more in the mind of the race. "A Newton, a La +Place, a Gauss, or a Cayley," would all alike have been impossible, but +for a previously prolonged course of mental evolution due to the +selection principle operating in the region of mathematics, by means of +continuous survivals of the best products in successive generations. +And, of course, the same remark applies to art in all its branches[22]. + + [22] In Prof. Lloyd Morgan's _Animal Life and Intelligence_ there is + an admirable discussion on this subject, which has been + published since the above was written. The same has to be said + of Weismann's Essay on Music, where much that I have here said + is anticipated. With the views and arguments which Mr. Mivart + has forcibly set forth I have already dealt to the best of my + ability in a work on _Mental Evolution in Man_. + +Quitting then the last, and in my opinion the weakest chapter of +_Darwinism_, the most important points presented by other portions of +this work are--to quote its author's own enumeration of them--an +attempted "proof that all specific characters are (or once have been) +either useful in themselves or correlated with useful characters": an +attempted "proof that natural selection can, in certain cases, increase +the sterility of crosses": an attempted "proof that the effects of use +and disuse, even if inherited, must be overpowered by natural +selection": an attempted proof that the facts of variation in nature are +in themselves sufficient to meet the difficulty which arises against the +theory of natural selection, as held by him, from the swamping effects +of free intercrossing: and, lastly, "a fuller discussion on the colour +relations of animals, with additional facts and arguments on the origin +of sexual differences of colour." As I intend to deal with all these +points hereafter, excepting the last, it will be sufficient in this +opening chapter to remark, that in as far as I disagree with Mr. Wallace +(and agree with Darwin), on the subject of "sexual differences of +colour," my reasons for doing so have been already sufficiently stated +in Part I. But there is much else in his treatment of this subject which +appears to me highly valuable, and therefore presenting an admirable +contribution to the literature of Darwinism. In particular, it appears +to me that the most important of his views in this connexion probably +represents the truth--namely, that, among the higher animals, more or +less conspicuous peculiarities of colour have often been acquired for +the purpose of enabling members of the same species quickly and +certainly to recognize one another. This theory was first published by +Mr. J. E. Todd, in 1888, and therefore but a short time before its +re-publication by Mr. Wallace. As his part in the matter has not been +sufficiently recognized, I should like to conclude this introductory +chapter by drawing prominent attention to the merits of Mr. Todd's +paper. For not only has it the merit of priority, but it deals with the +whole subject of "recognition colours"--or, as he calls them, "directive +colours"--in a more comprehensive manner than has been done by any of +his successors. In particular, he shows that the principle of +recognition-marking is not restricted to facilitating sexual +intercourse, but extends also to several other matters of importance in +the economy of animal life[23]. + + [23] _American Naturalist_, xxii. pp. 201-207. + + * * * * * + +Having thus briefly sketched the doctrines of the sundry Post-Darwinian +Schools from a general point of view, I shall endeavour throughout the +rest of this treatise to discuss in appropriate detail the questions +which have more specially come to the front in the post-Darwinian +period. It can scarcely be said that any one of these questions has +arisen altogether _de novo_ during this period; for glimmerings, more or +less conspicuous, of all are to be met with in the writings of Darwin +himself. Nevertheless it is no less true that only after his death have +they been lighted up to the full blaze of active discussion[24]. By far +the most important of them are those to which the rest of this treatise +will be confined. They are four in number, and it is noteworthy that +they are all intimately connected with the great question which Darwin +spent the best years of his life in contemplating, and which has +therefore, in one form or another, occupied the whole of the present +chapter--the question as to whether natural selection has been the sole +cause, or but the chief cause of modification. + + [24] It is almost needless to say that besides the works mentioned + in this chapter, many others have been added to the literature + of Darwinism since Darwin's death. But as none of these profess + to contain much that is original, I have not thought it + necessary to consider any of them in this merely general review + of the period in question. In subsequent chapters, however, + allusions will be made to those among them which I deem of most + importance. + + [Since this note was written and printed the following works + have been published to which it does not apply: _Animal Life + and Intelligence_, by Professor Lloyd Morgan; _The Colours of + Animals_, by Professor Poulton; and _Materials for the Study of + Variation_, by Mr. Bateson. All these works are of high value + and importance. Special reference should also be made to + Professor Weismann's Essays.] + +The four questions above alluded to appertain respectively to Heredity, +Utility, Isolation, and Physiological Selection. Of these the first two +will form the subject-matter of the present volume, while the last two +will be dealt with in the final instalment of _Darwin, and after +Darwin_. + + + + +SECTION I + +_HEREDITY_ + + + + +CHAPTER II. + +CHARACTERS AS HEREDITARY AND ACQUIRED (PRELIMINARY). + + +We will proceed to consider, throughout Section I of the present work, +the most important among those sundry questions which have come to the +front since the death of Darwin. For it was in the year after this event +that Weismann published the first of his numerous essays on the subject +of Heredity, and, unquestionably, it has been these essays which have +given such prominence to this subject during the last decade. + +At the outset it is desirable to be clear upon certain points touching +the history of the subject; the limits within which our discussion is to +be confined; the relation in which the present essay stands to the one +that I published last year under the title _An Examination of +Weismannism_; and several other matters of a preliminary kind. + +The problems presented by the phenomena of heredity are manifold; but +chief among them is the hitherto unanswered question as to the +transmission or non-transmission of acquired characters. This is the +question to which the present Section will be confined. + +Although it is usually supposed that this question was first raised by +Weismann, such was not the case. Any attentive reader of the successive +editions of Darwin's works may perceive that at least from the year 1859 +he had the question clearly before his mind; and that during the rest of +his life his opinion with regard to it underwent considerable +modifications--becoming more and more Lamarckian the longer that he +pondered it. But it was not till 1875 that the question was clearly +presented to the general public by the independent thought of Mr. +Galton, who was led to challenge the Lamarckian factors _in toto_ by way +of deduction from his theory of Stirp--the close resemblance of which to +Professor Weismann's theory of Germ-plasm has been shown in my +_Examination of Weismannism_. Lastly, I was myself led to doubt the +Lamarckian factors still further back in the seventies, by having found +a reason for questioning the main evidence which Mr. Darwin had adduced +in their favour. This doubt was greatly strengthened on reading, in the +following year, Mr. Galton's _Theory of Heredity_ just alluded to; and +thereupon I commenced a prolonged course of experiments upon the +subject, the general nature of which will be stated in future chapters. +Presumably many other persons must have entertained similar misgivings +touching the inheritance of acquired characters long before the +publication of Weismann's first essay upon the subject in 1883. The +question as to the inheritance of acquired characters was therefore +certainly not first raised by Weismann--although, of course, there is no +doubt that it was conceived by him independently, and that he had the +great merit of calling general attention to its existence and +importance. On the other hand, it cannot be said that he has succeeded +in doing very much towards its solution. It is for these reasons that +any attempt at dealing with Weismann's fundamental postulate--i.e. that +of the non-inheritance of acquired characters--was excluded from my +_Examination of Weismannism_. As there stated, he is justified in +assuming, for the purposes of his discussion, a negative answer to the +question of such inheritance; but evidently the question itself ought +not to be included within what we may properly understand by +"Weismannism." Weismannism, properly so called, is an elaborate system +of theories based on the fundamental postulate just mentioned--theories +having reference to the mechanism of heredity on the one hand, and to +the course of organic evolution on the other. Now it was the object of +the foregoing _Examination_ to deal with this system of theories _per +se_; and therefore we have here to take a new point of departure and to +consider separately the question of fact as to the inheritance or +non-inheritance of acquired characters. At first sight, no doubt, it +will appear that in adopting this method I am putting the cart before +the horse. For it may well appear that I ought first to have dealt with +the validity of Weismann's postulate, and not till then to have +considered the system of theories which he has raised upon it. But this +criticism is not likely to be urged by any one who is well acquainted +with the questions at issue. For, in the first place, it is notorious +that the question of fact is still open to question; and therefore it +ought to be considered separately, or apart from any theories which may +have been formed with regard to it. In the second place, our judgement +upon this question of fact must be largely influenced by the validity of +general reasonings, such as those put forward in the interests of rival +theories of heredity; and, as the theory of germ-plasm has been so +thoughtfully elaborated by Professor Weismann, I have sought to give it +the attention which it deserves as preliminary to our discussion of the +question of fact which now lies before us. Thirdly and lastly, even if +this question could be definitely answered by proving either that +acquired characters are inherited or that they are not, it would by no +means follow that Weismann's theory of heredity would be proved wholly +false in the one case, or wholly true in the other. That it need not be +wholly true, even were its fundamental postulate to be proved so, is +evident, because, although the fact might be taken to prove the theory +of Continuity, the theory of Germ-plasm is, as above stated, very much +more than this. That the theory of Germ-plasm need not be wholly false, +even if acquired characters should ever be proved heritable, a little +thought may easily show, because, in this event, the further question +would immediately arise as to the degrees and the comparative frequency +of such inheritance. For my own part, as stated in the _Examination_, I +have always been disposed to accept Mr. Galton's theory of Stirp in +preference to that of Germ-plasm on this very ground--i. e. that it does +not dogmatically exclude the possibility of an occasional inheritance of +acquired characters in faint though cumulative degrees. And whatever our +individual opinions may be touching the admissibility of such a _via +media_ between the theories of Pangenesis and Germ-plasm, at least we +may all agree on the desirability of fully considering the matter as a +preliminary to the discussion of the question of fact. + +As it is not to be expected that even those who may have read my +previous essay can now carry all these points in their memories, I will +here re-state them in a somewhat fuller form. + +The following diagram will serve to give a clearer view of the sundry +parts of Professor Weismann's system of theories, as well as of their +relations to one another. + +[Illustration: Postulate as to the absolute non-inheritance of acquired +characters.] + +Now, as just explained, the parts of this system which may be properly +and distinctively called "Weismannism" are those which go to form the +Y-like structure of deductions from the fundamental postulate. +Therefore, it was the Y-like system of deductions which were dealt with +in the _Examination of Weismannism_, while it is only his basal +postulate which has to be dealt with in the following chapters. + +So much, then, for the relations of Weismann's system of theories to one +another. It is, however, of even more importance that we should gain a +clear view of the relations between his theory of _heredity_ to those of +Darwin and of Galton, as preliminary to considering the fundamental +question of fact. + +As we have already seen, the theory of germ-plasm is not only a theory +of heredity: it is also, and more distinctively, a theory of evolution, +&c. As a theory of heredity it is grounded on its author's fundamental +postulate--the _continuity_ of germ-plasm. But as a theory of evolution, +it requires for its support this additional postulate, that the +continuity of germ-plasm has been _absolute_ "since the first origin of +life." It is clear that this additional postulate is not needed for his +theory of heredity, but only for his additional theory of evolution, &c. +There have been one or two other theories of heredity, prior to this +one, which, like it, have been founded on the postulate of Continuity of +the substance of heredity; but it has not been needful for any of these +theories to postulate further that this substance has been _always_ thus +isolated, or even that it is now _invariably_ so. For even though the +isolation be frequently invaded by influences of body-changes on the +congenital characters of this substance, it does not follow that this +principle of Continuity may not still be true _in the main_, even +although it is supplemented in some degree by that of use-inheritance. +Indeed, so far as the phenomena of heredity are concerned, it is +conceivable that all congenital characters were originally acquired, +and afterwards became congenital on account of their long inheritance. I +do not myself advocate this view as biologically probable, but merely +state it as logically possible, and in order to show that, so far as the +phenomena of heredity are concerned, there appears to be no reason for +Weismann's deduction that the principle of Continuity, if true at all, +must be _absolute_. And it would further appear, the only reason why he +makes this deduction (stem of the Y) is in order to provide a foundation +for his further theories of evolution, &c. (arms of the Y). It is indeed +necessary for these further theories that body-changes should never +exercise any hereditary influence on the hereditary endowments of +germ-plasm, and therefore it is that he posits the substance of heredity +as, not only continuous, but uninterruptably so "since the first origin +of life." + +Now, this may be made more clear by briefly comparing Weismann's theory +with those of Darwin and of Galton. Weismann's theory of heredity, then, +agrees with its predecessors which we are considering in all the +following respects. The substance of heredity is particulate; is mainly +lodged in highly specialized cells; is nevertheless also distributed +throughout the general cellular tissues, where it is concerned in all +processes of regeneration, repair, and a-sexual reproduction; presents +an enormously complex structure, in that every constituent part of a +potentially future organism is represented in a fertilized ovum by +corresponding particles; is everywhere capable of virtually unlimited +multiplication, without ever losing its hereditary endowments; is often +capable of carrying these endowments in a dormant state through a long +series of generations until at last they reappear in what we recognize +as recursions. Thus far all three theories are in agreement. In fact, +the only matter of any great importance wherein they disagree has +reference to the doctrine of Continuity[25]. For while Darwin's theory +supposes the substance of heredity to be mainly formed anew in each +ontogeny, and therefore that the continuity of this substance is for the +most part interrupted in every generation[26], Weismann's theory +supposes this substance to be formed only during the phylogeny of each +species, and therefore to have been absolutely uninterrupted since the +first origin of life. + + [25] Originally, Weismann's further assumption as to the perpetual + stability of germ-plasm, "since the first origin of sexual + reproduction," was another very important point of difference, + but this has now been withdrawn. + + [26] I say "_mainly_ formed anew," and "_for the most part_ + interrupted," because even Darwin's theory does not, as is + generally supposed, exclude the doctrine of Continuity _in + toto_. + +But now, Galton's theory of heredity stands much nearer to Weismann's in +this matter of Continuity; for it is, as he says, a theory of "modified +pangenesis," and the modification consists in allowing very much more +for the principle of Continuity than is allowed by Darwin's theory; in +fact he expresses himself as quite willing to adopt (on adequate grounds +being shown) the doctrine of Continuity as absolute, and therefore +propounded, as logically possible, the identical theory which was +afterwards and independently announced by Weismann. Or, to quote his own +words-- + + "We might almost reserve our belief that the structural [i. e. + somatic] cells can react on the sexual elements at all, and we may + be confident that at most they do so in a very faint degree; in + other words, that acquired modifications are barely, if at all, + _inherited_, in the correct sense of that word[27]." + + [27] _Theory of Heredity_ (Journ. Anthrop. Inst. 1875, p. 346). + +So far Mr. Galton; but for Weismann's further theory of evolution, &c., +it is necessary to postulate the additional doctrine in question; and it +makes a literally immeasurable difference to any theory of evolution +whether or not we entertain this additional postulate. For no matter how +faintly or how fitfully the substance of heredity may be modified by +somatic tissues, the Lamarckian principles are hypothetically allowed +some degree of play. And although this is a lower degree than Darwin +supposed, their influence in determining the course of organic evolution +may still have been enormous; seeing that their action in any degree +must always have been _directive_ of variation on the one hand, and +_cumulative_ on the other. + +Thus, by merely laying this theory side by side with Weismann's we can +perceive at a glance how a _pure_ theory of _heredity_ admits of being +based on the postulate of Continuity alone, without cumbering itself by +any further postulate as to this Continuity being _absolute_. And this, +in my opinion is the truly scientific attitude of mind for us to adopt +as preliminary to the following investigation. For the whole +investigation will be concerned--and concerned only--with this question +of Continuity as absolute, or as admitting of degrees. There is, without +any question, abundant evidence to prove that the substance of heredity +is at least partly continuous (Gemmules). It may be that there is also +abundant evidence to prove this substance much more _largely_ +continuous than Darwin supposed (Stirp); but be this as it may, it is +certain that any such question as to the _degree_ of continuity differs, +_toto caelo_, from that as to whether there can ever be any continuity +at all. + +How, then, we may well ask, is it that so able a naturalist and so clear +a thinker as Weismann can have so far departed from the inductive +methods as to have not merely propounded the question touching +Continuity and its degrees, or even of Continuity as absolute; but to +have straightway assumed the latter possibility as a basis on which to +run a system of branching and ever-changing speculations concerning +evolution, variation, the ultimate structure of living material, the +intimate mechanism of heredity, or, in short, such a system of deductive +conjectures as has never been approached in the history of science? The +answer to this question is surely not far to seek. Must it not be the +answer already given? Must it not have been for the sake of rearing this +enormous structure of speculation that Weismann has adopted the +assumption of Continuity as absolute? As we have just seen, Galton had +well shown how a theory of heredity could be founded on the general +doctrine of Continuity, without anywhere departing from the inductive +methods--even while fully recognizing the possibility of such continuity +as absolute. But Galton's theory was a "_Theory of Heredity_," and +nothing more. Therefore, while clearly perceiving that the Continuity in +question _may_ be absolute, he saw no reason, either in fact or in +theory, for concluding that it _must_ be. On the contrary, he saw that +this question is, for the present, necessarily unripe for profitable +discussion--and, _a fortiori_, for the shedding of clouds of seed in all +the directions of "Weismannism." + +Hence, what I desire to be borne in mind throughout the following +discussion is, that it will have exclusive reference to the question of +fact already stated, without regard to any superjacent theories; and, +still more, that there is a vast distinction between any question +touching the degrees in which acquired characters are transmitted to +progeny, and the question as to whether they are ever transmitted in any +degree at all. Now, the latter question, being of much greater +importance than the former, is the one which will mainly occupy our +attention throughout the rest of this Section. + +We have already seen that before the subject was taken up by Weismann +the difference between acquired and congenital characters in respect to +transmissibility was generally taken to be one of degree; not one of +kind. It was usually supposed that acquired characters, although not so +fully and not so certainly inherited as congenital characters, +nevertheless were inherited in some lesser degree; so that if the same +acquired character continued to be successively acquired in a number of +sequent generations, what was at first only a slight tendency to be +inherited would become by summation a more and more pronounced tendency, +till eventually the acquired character might become as strongly +inherited as a congenital one. Or, more precisely, it was supposed that +an acquired character, in virtue of such a summation of hereditary +influence, would in time become congenital. Now, if this supposition be +true, it is evident that more or less assistance must be lent to +natural selection in its work of evolving adaptive modifications[28]. +And inasmuch as we know to what a wonderful extent adaptive +modifications are secured during individual life-times--by the direct +action of the environment on the one hand, and by increased or +diminished use of special organs and mental faculties on the other--it +becomes obvious of what importance even a small measure of +transmissibility on their part would be in furnishing to natural +selection ready-made variations in required directions, as distinguished +from promiscuous variations in all directions. Contrariwise, if +functionally-produced adaptations and adaptations produced by the direct +action of the environment are never transmitted in any degree, not only +would there be an incalculable waste, so to speak, of adaptive +modifications--these being all laboriously and often most delicately +built up during life-times of individuals only to be thrown down again +as regards the interest of species--but so large an additional burden +would be thrown upon the shoulders of natural selection that it becomes +difficult to conceive how even this gigantic principle could sustain it, +as I shall endeavour to show more fully in future chapters. On the other +hand, however, Weismann and his followers not only feel no difficulty in +throwing overboard all this ready-made machinery for turning out +adaptive modifications when and as required; but they even represent +that by so doing they are following the logical maxim, _Entia non sunt +multiplicanda praeter necessitatem_--which means, in its relation to +causality, that we must not needlessly multiply hypothetical principles +to explain given results. But when appeal is here made to this logical +principle--the so-called Law of Parsimony--two things are forgotten. + + [28] Mr. Platt Ball has, indeed, argued that "use-inheritance would + often be an evil," since, for example, "the condyle of the + human jaw would become larger than the body of the jaw, because + as the fulcrum of the lever it receives more pressure"; and + similarly as regards many other hypothetical cases which he + mentions. (_The Effects of Use and Disuse_, pp. 128-9 _et + seq._) But it is evident that this argument proves too much. + For if the effects of use and disuse as transmitted to progeny + would be an evil, it could only be because these effects as + they occur in the parents are an evil--and this they most + certainly are not, being, on the contrary and as a general + rule, of a high order of adaptive value. Moreover, in the race, + there is a superadded agency always at work, which must + effectually prevent any undue accumulation of these + effects--namely, natural selection, which every Darwinist + accepts as a controlling principle of all or any other + principles of change. Therefore, if, as first produced in the + life-time of individuals, the effects of use and disuse are not + injurious, much less can they become so if transmitted through + the life-time of species. Again, Mr. Wallace argues that, even + supposing use-inheritance to occur, its adapting work in the + individual can never extend to the race, seeing that the + natural selection of fortuitous variations in the directions + required must always produce the adaptations _more quickly_ + than would be possible by use-inheritance. This argument, being + one of more weight, will be dealt with in a future chapter. + +In the first place, it is forgotten that the very question in debate is +whether causes of the Lamarckian order _are_ unnecessary to explain all +the phenomena of organic nature. Of course if it could be proved that +the theory of natural selection alone is competent to explain all these +phenomena, appeal to the logical principle in question would be +justifiable. But this is precisely the point which the followers of +Darwin refuse to accept; and so long as it remains the very point at +issue, it is a mere begging the question to represent that a class of +causes which have hitherto been regarded as necessary are, in fact, +unnecessary. Or, in other words, when Darwin himself so decidedly held +that these causes are necessary as supplements to natural selection, the +burden of proof is quite as much on the side of Weismann and his +followers to show that Darwin's opinion was wrong, as it is on the side +of Darwin's followers to show that it was right. Yet, notwithstanding +the elaborate structure of theory which Weismann has raised, there is +nowhere one single fact or one single consideration of much importance +to the question in debate which was not perfectly well known to Darwin. +Therefore I say that all this challenging of Darwinists to justify their +"Lamarckian assumptions" really amounts to nothing more than a pitting +of opinion against opinion, where there is at least as much call for +justification on the one side as on the other. + +Again, when these challenges are thrown down by Weismann and his +followers, it appears to be forgotten that the conditions of their own +theory are such as to render acceptance of the gauge a matter of great +difficulty. The case is very much like that of a doughty knight pitching +his glove into the sea, and then defying any antagonist to take it up. +That this is the case a very little explanation will suffice to show. + +The question to be settled is whether acquired characters are ever +transmitted by heredity. Now suppose, for the sake of argument, that +acquired characters are transmitted by heredity--though not so fully and +not so certainly as congenital characters--how is this fact to be proved +to the satisfaction of Weismann and his followers? First of all they +answer,--Assuredly by adducing experimental proof of the inheritance of +injuries, or mutilations. But in making this answer they appear to +forget that Darwin has already shown its inefficiency. That the +self-styled Neo-Lamarckians have been much more unguarded in this +respect, I fully admit; but it is obviously unfair to identify Darwin's +views with those of a small section of evolutionists, who are really as +much opposed to Darwin's teaching on one side as is the school of +Weismann on the other. Yet, on reading the essays of Weismann +himself--and still more those of his followers--one would almost be led +to gather that it is claimed by him to have enunciated the distinction +between congenital and acquired characters in respect of +transmissibility; and therefore also to have first raised the objection +which lies against the theory of Pangenesis in respect of the +non-transmissibility of mutilations. In point of fact, however, Darwin +is as clear and decided on these points as Weismann. And his answer to +the obvious difficulty touching the non-transmissibility of mutilations +is, to quote his own words, "the long-continued inheritance of a part +which has been removed during many generations is no real anomaly, for +gemmules formerly derived from the part are multiplied and transmitted +from generation to generation[29]." Therefore, so far as Darwin's theory +is concerned, the challenge to produce evidence of the transmission of +injuries is irrelevant: it is no more a part of Darwin's theory than it +is of Weismann's to maintain that injuries _are_ transmitted. + + [29] _Variation under Domestication_, ii. 392. + +There is, however, one point in this connexion to which allusion must +here be made. Although Darwin did not believe in the transmissibility +of mutilations when these consist merely in the amputation of parts of +an organism, he did believe in a probable tendency to transmission when +removal of the part is followed by gangrene. For, as he says, in that +case, all the gemmules of the mutilated or amputated part, as they are +gradually attracted to that part (in accordance with the law of affinity +which the theory assumes), will be successively destroyed by the morbid +process. Now it is of importance to note that Darwin made this exception +to the general rule of the non-transmissibility of mutilations, not +because his theory of pangenesis required it, but because there appeared +to be certain very definite observations and experiments--which will be +mentioned later on--proving that when mutilations are followed by +gangrene they are apt to be inherited: his object, therefore, was to +reconcile these alleged facts with his theory, quite as much as to +sustain his theory by such facts. + +So much, then, for the challenge to produce direct evidence of the +transmissibility of acquired characters, so far as mutilations are +concerned: believers in Darwin's theory, as distinguished from +Weismann's, are under no obligation to take up such a challenge. But the +challenge does not end here. Show us, say the school of Weismann, a +single instance where an acquired character _of any kind_ (be it a +mutilation or otherwise) has been inherited: this is all that we +require: this is all that we wait for: and surely, unless it be +acknowledged that the Lamarckian doctrine reposes on mere assumption, at +least one such case ought to be forthcoming. Well, nothing can sound +more reasonable than this in the first instance; but as soon as we +begin to cast about for cases which will satisfy the Neo-Darwinians, we +find that the structure of their theory is such as to preclude, in +almost every conceivable instance, the possibility of meeting their +demand. For their theory begins by assuming that natural selection is +the one and only cause of organic evolution. Consequently, what their +demand amounts to is throwing upon the other side the burden of +disproving this assumption--or, in other words, of proving the negative +that in any given case of transmitted adaptation natural selection has +_not_ been the sole agent at work. Now, it must obviously be in almost +all cases impossible to prove this negative among species in a state of +nature. For, even supposing that among such species Lamarckian +principles have had a large share in the formation of hereditary and +adaptive characters, how would Weismann himself propose that we should +set about the proof of such a fact, where the proof demanded by his +assumption is, that the _abstract possibility_ of natural selection +having had anything to do with the matter must be excluded? Obviously +this is impossible in the case of inherited characters which are also +_adaptive_ characters. How then does it fare with the case of inherited +characters which are not also adaptive? Merely that this case is met by +another and sequent assumption, which constitutes an integral part of +the Neo-Darwinian creed--namely, that in nature there _can be no such +characters_. Seeing that natural selection is taken to be the only +possible cause of change in species, it follows that all changes +occurring in species must necessarily be adaptive, whether or not we are +able to perceive the adaptations. In this way apparently useless +characters, as well as obviously useful ones, are ruled out of the +question: that is to say, _all_ hereditary characters of species in a +state of nature are _assumed_ to be due to natural selection, and then +it is demanded that the validity of this assumption should be disproved +by anybody who doubts it. Yet Weismann himself would be unable to +suggest any conceivable method by which it can be disproved among +species in a state of nature--and this even supposing that the +assumption is entirely false[30]. + + [30] In subsequent chapters, especially devoted to the question + (i.e. Section II), the validity of this assumption will be + considered on its own merits. + +Consequently, the only way in which these speciously-sounding challenges +can be adequately met is by removing some individuals of a species from +a state of nature, and so from all known influences of natural +selection; then, while carefully avoiding artificial selection, causing +these individuals and their progeny through many generations unduly to +exercise some parts of their bodies, or unduly to fail in the exercise +of others. But, clearly, such an experiment is one that must take years +to perform, and therefore it is now too early in the day to reproach the +followers of Darwin with not having met the challenges which are thrown +down by the followers of Weismann[31]. + + [31] I say "the followers of Weismann," because Weismann himself, + with his clear perception of the requirements of experimental + research, expressly states the above considerations, with the + conclusions to which they lead. Nevertheless, he is not + consistent in his utterances upon this matter; for he + frequently expresses himself to the effect, "that the _onus + probandi_ rests with my opponents, and therefore they ought to + bring forward actual proofs" (_Essays_, i. p. 390). But, as + above shown, the _onus_ rests as much with him as with his + opponents; while, even if his opponents are right, he elsewhere + recognizes that they can bring "actual proofs" of the fact only + as a result of experiments which must take many years to + perform. + +Probably enough has now been said to show that the Neo-Darwinian +assumption precludes the possibility of its own disproof from any of the +facts of nature (as distinguished from domestication)--and this even +supposing that the assumption be false. On the other hand, of course, it +equally precludes the possibility of its own proof; and therefore it is +as idle in Darwinists to challenge Weismann for proof of his negative +(i. e. that acquired characters are not transmitted), as it is in +Weismann to challenge Darwinists for proof of the opposite negative (i. +e. that all seeming cases of such transmission are not due to natural +selection). This dead-lock arises from the fact that in nature it is +beyond the power of the followers of Darwin to exclude the abstract +possibility of natural selection in any given case, while it is equally +beyond the power of the followers of Weismann to exclude the abstract +possibility of Lamarckian principles. Therefore at present the question +must remain for the most part a matter of opinion, based upon general +reasoning as distinguished from special facts or crucial experiments. +The evidence available on either side is presumptive, not +demonstrative[32]. But it is to be hoped that in the future, when time +shall have been allowed for the performance of definite experiments on a +number of generations of domesticated plants or animals, intentionally +shielded from the influences of natural selection while exposed to those +of the Lamarckian principles, results will be gained which will finally +settle the question one way or the other. + + [32] Note A. + +Meanwhile, however, we must be content with the evidence as it stands; +and this will lead us to the second division of our subject. That is to +say, having now dealt with the antecedent, or merely logical, state of +the question, we have next to consider what actual, or biological, +evidence there is at present available on either side of it. Thus far, +neither side in the debate has any advantage over the other. On grounds +of general reasoning alone they both have to rely on more or less +dogmatic assumptions. For it is equally an unreasoned statement of +opinion whether we allege that all the phenomena of organic evolution +can be, or can not be, explained by the theory of natural selection +alone. We are at present much too ignorant touching the causes of +organic evolution to indulge in dogmatism of this kind; and if the +question is to be referred for its answer to authority, it would appear +that, both in respect of number and weight, opinions on the side of +having provisionally to retain the Lamarckian factors are more +authoritative than those _per contra_[33]. + + [33] For a fair and careful statement of the present balance of + authoritative opinion upon the question, see H. F. Osborn, + _American Naturalist_, 1892, pp. 537-67. + + * * * * * + +Turning then to the question of fact, with which the following chapters +are concerned, I will conclude this preliminary one with a few words on +the method of discussion to be adopted. + +First I will give the evidence in favour of Lamarckianism; this will +occupy the next two chapters. Then, in Chapter V, I will similarly give +the evidence _per contra_, or in favour of Continuity as absolute. +Lastly, I will sum up the evidence on both sides, and give my own +judgement on the whole case. But on whichever side I am thus acting as +special pleader for the time being, I will adduce only such arguments as +seem to me valid--excluding alike from both the many irrelevant or +otherwise invalid reasonings which have been but too abundantly +published. Moreover, I think it will be convenient to consider all that +has been said--or may be said--in the way of criticism to each argument +by the opposite side while such argument is under discussion--i. e. not +to wait till all the special pleading on one side shall have been +exhausted before considering the exceptions which have been (or admit of +being) taken to the arguments adduced, but to deal with such exceptions +at the time when each of these arguments shall have been severally +stated. Again, and lastly, I will arrange the evidence in each case--i. +e. on both sides--under three headings, viz. (A) Indirect, (B) Direct, +and (C) Experimental[34]. + + [34] [The above paragraph is allowed to remain exactly as Mr. + Romanes left it. Chapters V and VI were however not completed. + _See_ note appended to Preface. C. Ll. M.] + + + + +CHAPTER III. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(A.) +_Indirect Evidence in favour of the Inheritance of Acquired Characters._ + + +Starting with the evidence in favour of the so-called Lamarckian +factors, we have to begin with the Indirect--and this without any +special reference to the theories, either of Weismann or of others. + +It has already been shown, while setting forth in the preceding chapter +the antecedent standing of the issue, that in this respect the _prima +facie_ presumption is wholly on the side of the transmission, in greater +degree or less, of acquired characters. Even Weismann allows that all +"_appearances_" point in this direction, while there is no inductive +evidence of the action of natural selection in any one case, either as +regards germs or somas, and therefore, _a fortiori_, of the +"all-sufficiency" of this cause[35]. It is true that in some of his +earlier essays he has argued that there is no small weight of _prima +facie_ evidence in favour of his own views as to the non-inheritance of +acquired characters. This, however, will have to be considered in its +proper place further on. Meanwhile I shall say merely in general terms +that it arises almost entirely from a confusion of the doctrine of +Continuity as absolute with that of Continuity as partial, and +therefore, as admitting of degrees in different cases--which, as already +explained, are doctrines wide as the poles asunder. But, leaving aside +for the present such _prima facie_ evidence as Weismann has adduced on +his side of the issue, I may quote him as a hostile witness to the +weight of this kind of evidence _per contra_, in so far as it has +already been presented in the foregoing chapter. Indeed, Weismann is +much too logical a thinker not to perceive the cogency of the +"appearances" which lie against his view of Continuity as +absolute--although he has not been sufficiently careful in +distinguishing between such Continuity and that which admits of degrees. + + [35] See, especially, his excellent remarks on this point, _Contemp. + Rev._ Sept. 1893. + +We may take it, then, as agreed on all hands that whatever weight merely +_prima facie_ evidence may in this matter be entitled to, is on the side +of what I have termed moderated Lamarckianism: first sight "appearances" +are against the Neo-Darwinian doctrine of the absolute non-inheritance +of acquired characters. + + * * * * * + +Let us now turn to another and much more important line of indirect +evidence in favour of moderated Lamarckianism. + +The difficulty of _excluding the possibility_ of natural selection +having been at work in the case of wild plants and animals has already +been noticed. Therefore we may now appreciate the importance of all +facts or arguments which _attenuate the probability_ of natural +selection having been at work. This may be done by searching for cases +in nature where a congenital structure, although unquestionably +adaptive, nevertheless presents so small an amount of adaptation, that +we can scarcely suppose it to have been arrived at by natural selection +in the struggle for existence, as distinguished from the inheritance of +functionally-produced modifications. For if functionally-produced +modifications are ever transmitted at all, there is no limit to the +minuteness of adaptive values which may thus become congenital; whereas, +in order that any adaptive structure or instinct should be seized upon +and accumulated by natural selection, it must from the very first have +had an adaptive value sufficiently great to have constituted its +presence a matter of life and death in the struggle for existence. Such +structures or instincts must not only have always presented some measure +of adaptive value, but this must always have been sufficiently great to +reach what I have elsewhere called a selection-value. Hence, if we meet +with cases in nature where adaptive structures or instincts present so +low a degree of adaptive value that it is difficult to conceive how they +could ever have exercised any appreciable influence in the battle for +life, such cases may fairly be adduced in favour of the Lamarckian +theory. For example, the Neo-Lamarckian school of the United States is +chiefly composed of palaeontologists; and the reason of this seems to be +that the study of fossil forms--or of species in process of +formation--reveals so many instances of adaptations which in their +nascent condition present such exceedingly minute degrees of adaptive +value, that it seems unreasonable to attribute their development to a +survival of the fittest in the complex struggle for existence. But as +this argument is in my opinion of greatest force when it is applied to +certain facts of physiology with which I am about to deal, I will not +occupy space by considering any of the numberless cases to which the +Neo-Lamarckians apply it within the region of palaeontology[36]. + + [36] There is now an extensive literature within this region. The + principal writers are Cope, Scott and Osborn. Unfortunately, + however, the facts adduced are not crucial as test-cases + between the rival theories--nearly all of them, in fact, being + equally susceptible of explanation by either. + +Turning then to inherited actions, it is here that we might antecedently +expect to find our best evidence of the Lamarckian principles, if these +principles have really had any share in the process of adaptive +evolution. For we know that in the life-time of individuals it is +action, and the cessation of action, which produce nearly all the +phenomena of acquired adaptation--use and disuse in animals being merely +other names for action and the cessation of action. Again, we know that +it is where neuro-muscular machinery is concerned that we meet with the +most conclusive evidence of the remarkable extent to which action is +capable of co-ordinating structures for the ready performance of +particular functions; so that even during the years of childhood +"practice makes perfect" to the extent of organizing neuro-muscular +adjustments, so elaborate and complete as to be indistinguishable from +those which in natural species we recognized as reflex actions on the +one hand, and instinctive actions on the other. Hence, if there be any +such thing as "use-inheritance" at all, it is in the domain of reflex +actions and instinctive actions that we may expect to find our best +evidence of the fact. Therefore I will restrict the present line of +evidence--(A)--to these two classes of phenomena, as together yielding +the best evidence obtainable within this line of argument. + + * * * * * + +The evidence in favour of the Lamarckian factors which may be derived +from the phenomena of reflex action has never, I believe, been pointed +out before; but it appears to me of a more cogent nature than perhaps +any other. In order to do it justice, I will begin by re-stating an +argument in favour of these factors which has already been adduced by +previous writers, and discussed by myself in published correspondence +with several leaders of the ultra-Darwinian school. + +Long ago Professor Broca and Mr. Herbert Spencer pointed to the facts of +co-adaptation, or co-ordination within the limits of the same organism, +as presenting good evidence of Lamarckian principles, working in +association with natural selection. Thus, taking one of Lamarck's own +illustrations, Mr. Spencer argued that there must be numberless +changes--extending to all the organs, and even to all the tissues, of +the animal--which in the course of many generations have conspired to +convert an antelope into a giraffe. Now the point is, that throughout +the entire history of these changes their utility must always have been +dependent on their association. It would be useless that an incipient +giraffe should present the peculiar form of the hind-quarters which we +now perceive, unless at the same time it presented the correspondingly +peculiar form of the fore-quarters; and as each of these great +modifications entails innumerable subordinate modifications throughout +both halves of the creature concerned, the chances must have been +infinitely great against the required association of so many changes +happening to have arisen congenitally in the same individuals by way of +merely fortuitous variation. Yet, if we exclude the Lamarckian +interpretation, which gives an intelligible _cause_ of co-ordination, we +are required to suppose that such a happy concurrence of innumerable +independent variations must have occurred by mere accident--and this on +innumerable different occasions in the bodies of as many successive +ancestors of the existing species. For at each successive stage of the +improvement natural selection (if working alone) must have needed all, +or at any rate most, of the co-ordinated parts to occur in the same +individual organisms[37]. + + [37] For another and better illustration more recently published by + Mr. Spencer, see _The Inadequacy of Natural Selection_, p. 22. + +In alluding to what I have already published upon the difficulty which +thus appears to be presented to his theory, Weismann says, "At no +distant time I hope to be able to consider this objection, and to show +that the apparent support given to the old idea [i. e. of the +transmission of functionally-produced modifications] is really insecure, +and breaks down as soon as it is critically examined[38]." + + [38] _Essays on Heredity_, vol. i. p. 389. + + [For further treatment of the subject under discussion _see_ + Weismann, _The All-sufficiency of Natural Selection_ (Contemp. + Rev. Sept. and Oct. 1893), and _The Effect of External + Influences upon Development_. "Romanes Lecture" 1894, and + Spencer, _Weismannism once more_ (Cont. Rev. Oct. 1894). C. Ll. + M.] + +So much for what Weismann has said touching this matter. But the matter +has also been dealt with both by Darwin and by Wallace. Darwin very +properly distinguishes between the fallacy that "with animals such as +the giraffe, of which the whole structure is admirably co-ordinated for +certain purposes, it has been supposed that all the parts must have been +simultaneously modified[39]," and the sound argument that the +co-ordination itself cannot have been due to natural selection alone. +This important distinction may be rendered more clear as follows. + + [39] _Variation_, &c., vol. ii. p. 206. + +The facts of artificial selection prove that immense modifications of +structure may be caused by a cumulative blending in the same individuals +of characters which were originally distributed among different +individuals. Now, in the parallel case of natural selection the +characters thus blended will usually--if not invariably--be of an +adaptive kind; and their eventual blending together in the same +individuals will be due to free intercrossing of the most fit. But this +_blending of adaptations_ is quite a different matter from the +_occurrence of co-ordination_. For it belongs to the essence of +co-ordination that each of the co-ordinated parts should be destitute of +adaptive value _per se_: the adaptation only begins to arise if all the +parts in question occur associated together in the same individuals +_from the very first_. In this case it is obvious that the analogy of +artificial selection can be of no avail in explaining the facts, since +the difficulty presented has nothing to do with the blending in single +individuals of adaptations previously distributed among different +individuals; it has to do with the simultaneous appearance in single +individuals of a co-adaptation of parts, none of which could ever have +been of any adaptive value had it been previously distributed among +different individuals. Consequently, where Darwin comes to consider this +particular case (or the case of co-adaptation as distinguished from the +blending of adaptations), he freely invokes the aid of the Lamarckian +principles[40]. + + [40] E. g. _Origin of Species_, p. 178. + +Wallace, on the other hand, refuses to do this, and says that "the best +answer to the difficulty" of supposing natural selection to have been +the only cause of co-adaptation may be "found in the fact that the very +thing said to be impossible by variation and natural selection, has been +again and again affected by variation and artificial selection[41]." +This analogy (which Darwin had already and very properly adduced with +regard to the _blending of adaptations_) he enforces by special +illustrations; but he does not appear to perceive that it misses the +whole and only point of the "difficulty" against which it is brought. +For the case which his analogy sustains is not that which Darwin, +Spencer, Broca and others, mean by _co-adaptation_: it is the case of a +blending of _adaptations_. It is not the case where adaptation is _first +initiated in spite of intercrossing_, by a fortuitous concurrence of +variations each in itself being without adaptive value: it is the case +where adaptation is _afterwards increased by means of intercrossing_, +through the blending of variations each of which has always been in +itself of adaptive value. + + [41] _Darwinism_, p. 418. + +From this I hope it will be apparent that the only way in which the +"difficulty" from co-adaptation can be logically met by the +ultra-Darwinian school, is by denying that the phenomenon of +co-adaptation (as distinguished from the blending of adaptations) is +ever to be really met with in organic nature. It may be argued that in +all cases where co-adaptation _appears_ to occur, closer examination +will show that the facts are really due to a blending of adaptations. +The characters A + B + C + D, which are now found united in the same +organism, and, as thus united, all conspiring to a common end, may +originally have been distributed among different organisms, where they +_severally_ subserved some other ends--or possibly the same end, though +in a less efficient manner. Obviously, however, in this case their +subsequent combination in the same organism would not be an instance of +co-adaptation, but merely of an advantageous blending together of +already existing adaptations. This argument, or rejoinder, has in point +of fact been adopted by Professor Meldola, he believes that all cases of +seeming co-adaptation are thus due to a mere blending of +adaptations[42]. Of course, if this position can be maintained, the +whole difficulty from co-adaptation would lapse. But even then it would +lapse on the ground of _fact_. It would not have been overturned, or in +any way affected, by Wallace's _argument_ from artificial selection. +For, in that event, no such argument would be required, and, if adduced, +would be irrelevant, since no one has ever alleged that there is any +difficulty in understanding the mere confluence of adaptations by +free-intercrossing of the best adapted. + + [42] _Nature_, vol. xliii. pp. 410, 557; vol. xliv. pp. 7, 29. I say + "adopted," because I had objected to his quoting the analogy of + artificial selection, and stated, as above, that the only way + to meet Mr. Spencer's "difficulty" was to deny the fact of + co-adaptation as ever occurring in any case. It then appeared + that Professor Meldola agreed with me as to this. But I do not + yet understand why, if such were his view, he began by + endorsing Mr. Wallace's analogy from artificial selection--i. + e. confusing the case of co-adaptation with that of the + blending of adaptations. If any one denies the fact of + co-adaptation, he cannot assist his denial by arguing the + totally different fact that adaptations may be blended by free + intercrossing; for this latter fact has never been questioned, + and has nothing to do with the one which he engaged in + disputing. + +Now, if we are agreed that the only question in debate is the question +of fact whether or not co-adaptation ever occurs in nature, it appears +to me that the best field for debating the question is furnished by the +phenomena of reflex action. I can well perceive that the instances +adduced by Broca and Spencer in support of their common argument--such +as the giraffe, the elk, &c.--are equivocal. But I think that many +instances which may be adduced of reflex action are much more to the +point. _For it belongs to the very nature of reflex action that it +cannot work unless all parts of the machinery concerned are already +present, and already co-ordinated, in the same organism._ It would be +useless, in so far as such action is concerned if the afferent and +efferent nerves, the nerve-centre, and the muscles organically grouped +together, were not all present from the very first in the same +individuals, and from the very first were not co-ordinated as a definite +piece of organic machinery. + +With respect to reflex actions, therefore, it is desirable to begin by +pointing out how widely the adaptations which they involve differ from +those where no manufacture, so to speak, of special machinery is +required. Thus, it is easy to understand how natural selection alone is +capable of gradually accumulating congenital variations in the direction +of protective colouring; of mimicry; of general size, form, mutual +correlation of parts as connected with superior strength, fleetness, +agility, &c.; of greater or less development of particular parts, such +as legs, wings, tails, &c. For in all such cases the adaptation which is +in process of accumulation is from its very commencement and throughout +each of its subsequent stages, of _use_ in the struggle for existence. +And inasmuch as all the individuals of each successive generation vary +round the specific mean which characterized the preceding generation, +there will always be a sufficient number of individuals which present +congenital variations of the kind required for natural selection to +seize upon, without danger of their being swamped by free +intercrossing--as Mr. Wallace has very ably shown in his _Darwinism_. +But this law of averages can apply only to cases where single +structures--or a single group of correlated structures--are already +present, and already varying round a specific mean. The case is quite +different where a _co-ordination_ of structures is required for the +performance of a _previously non-existent_ reflex action. For some, at +least, of these structures must be _new_, as must also be the function +which all of them first conspire to perform. Therefore, neither the new +elements of structure, nor the new combination of structures, can have +been previously given as varying round a specific mean. On the contrary, +a very definite piece of machinery, consisting of many co-ordinated +parts, must somehow or other be originated in a high degree of working +efficiency, before it can be capable of answering its purpose in the +prompt performance of a particular action under particular circumstances +of stimulation. Lastly, such pieces of machinery are always of a highly +delicate character, and usually involve so immensely complex a +co-ordination of mutually dependent parts, that it is only a +physiologist who can fully appreciate the magnitude of the distinction +between "adaptations" of this kind, and "adaptations" of the kind which +arise through natural selection seizing upon congenital variations as +these oscillate round a specific mean. + +Or the whole argument may be presented in another form, under three +different headings, thus:-- + +In the first place, it will be evident from what has just been said, +that such a piece of machinery as is concerned in even the simplest +reflex action cannot have occurred in any considerable number of +individuals of a species, _when it first began to be constructed_. On +the contrary, if its _origin_ were dependent on congenital variations +alone, the needful co-adaptation of parts which it requires can scarcely +have happened to occur in more than a very small percentage of +cases--even if it be held conceivable that by such means alone it should +ever have occurred at all. Hence, instead of preservation and subsequent +improvement having taken place _in consequence of_ free intercrossing +among all individuals of the species (as in the cases of protective +colouring, &c., where adaptation has no reference to any mechanical +co-adaptation of parts), they must have taken place _in spite of_ such +intercrossing. + +In the second place, adaptations due to organic machineries of this kind +differ in another all-important respect from those due to a summation of +adaptive characters which are already present and already varying round +a specific mean. The latter depend for their summation upon the +fact--not merely, as just stated, that they are already present, already +varying round a specific mean, and therefore owe their progressive +evolution to free intercrossing, but also--_that they admit of very +different degrees of adaptation_. It is only because the degree of +adaptation in generation B is superior to that in generation A that +_gradual improvement_ in respect of adaptation is here possible. In the +case of protective resemblance, for example, a very imperfect and merely +accidental resemblance to a leaf, to another insect, &c., may at the +first start have conferred a sufficient degree of adaptive imitation to +count for something in the struggle for life; and, if so, the basis +would be given for a progressive building up by natural selection of +structures and colours in ever-advancing degrees of adaptive +resemblance. There is here no necessity to suppose--nor in point of fact +is it ever supposed, since the supposition would involve nothing short +of a miracle--that such extreme perfection in this respect as we now so +frequently admire has originated suddenly in a single generation, as a +collective variation of a congenital kind affecting simultaneously a +large proportional number of individuals. But in the case of a reflex +mechanism--which may involve even greater marvels of adaptive +adjustment, and _all_ the parts of which must occur in the same +_individuals_ to be of any use--it _is_ necessary to suppose some such +sudden and collective origin in some very high degree of efficiency, if +natural selection has been the only principle concerned in afterwards +perfecting the mechanism. For it is self-evident that a reflex action, +from its very nature, cannot admit of any great differences in its +degrees of adaptation: if it is to work at all, so as to count for +anything in the struggle for life, it must already be given in a state +of working efficiency. So that, unless we invoke either the doctrine of +"prophetic types" or the theory of sudden creations, I confess I do not +see how we are to explain either the origin, or the development, of a +reflex mechanism by means of natural selection alone. + +Lastly, in the third place, _even when reflex mechanisms have been fully +formed_, it is often beyond the power of sober credence to believe that +they now are, or ever can have been, of selective value in the struggle +for existence, as I will show further on. And such cases go to fortify +the preceding argument. For if not conceivably of selective value even +when completely evolved, much less can they conceivably have been so +through all the stages of their complex evolution back to their very +origin. Therefore, supposing for the present that there are such cases +of reflex action in nature, neither their origin nor their development +can conceivably have been due to natural selection alone. The Lamarckian +factors, however, have no reference to degrees of adaptation, any more +than they have to degrees of complexity. No question of value, as +selective or otherwise, can obtain in their case: neither in their case +does any difficulty obtain as regards the co-adaptation of severally +useless parts. + +Now, if all these distinctions between the Darwinian and Lamarckian +principles are valid--and I cannot see any possibility of doubt upon +this point--strong evidence in favour of the latter would be furnished +by cases (if any occur) where structures, actions, instincts, &c., +although of some adaptive value, are nevertheless plainly not of +selective value. According to the ultra-Darwinian theory, no such cases +ought ever to occur: according to the theory of Darwin himself, they +ought frequently to occur. Therefore a good test, or criterion, as +between these different theories of organic evolution is furnished by +putting the simple question of fact--Can we, or can we not, show that +there are cases of adaptation where the degree of adaptation is so small +as to be incompatible with the supposition of its presenting a selective +value? And if we put the wider question--Are there any cases where the +co-adaptation of severally useless parts has been brought about, when +even the resulting whole does not present a selective value?--then, of +course, we impose a still more rigid test. + +Well, notwithstanding the difficulty of proving such a negative as the +absence of natural selection where adaptive development is concerned, I +believe that there are cases which conform to both these tests +simultaneously; and, moreover, that they are to be found in most +abundance where the theory of use-inheritance would most expect them to +occur--namely, in the province of reflex action. For the very essence of +this theory is the doctrine, that constantly associated use of the same +parts for the performance of the same action will progressively organize +those parts into a reflex mechanism--no matter how high a degree of +co-adaptation may thus be reached on the one hand, or how low a degree +of utilitarian value on the other. + +Having now stated the general or abstract principles which I regard as +constituting a defence of the Lamarckian factors, so far as this admits +of being raised on grounds of physiology, we will now consider a few +concrete cases by way of illustration. It is needless to multiply such +cases for the mere purpose of illustration. For, on reading those here +given, every physiologist will at once perceive that they might be added +to indefinitely. The point to observe is, the relation in which these +samples of reflex action stand to the general principles in question; +for there is nothing unusual in the samples themselves. On the contrary, +they are chosen because they are fairly typical of the phenomena of +reflex action in general. + +In our own organization there is a reflex mechanism which ensures the +prompt withdrawal of the legs from any source of irritation supplied to +the feet. For instance, even after a man has broken his spine in such a +manner as totally to interrupt the functional continuity of his spinal +cord and brain, the reflex mechanism in question will continue to +retract his legs when his feet are stimulated by a touch, a burn, &c. +This responsive action is clearly an adaptive action, and, as the man +neither feels the stimulation nor the resulting movement, it is as +clearly a reflex action. The question now is as to the mode of its +origin and development. + +I will not here dwell upon the argument from co-adaptation, because this +may be done more effectually in the case of more complicated reflex +actions, but will ask whether we can reasonably hold that this +particular reflex action--comparatively simple though it is--has ever +been of selective value to the human species, or to the ancestors +thereof? Even in its present fully-formed condition it is fairly +questionable whether it is of any adaptive _value_ at all. The movement +performed is no doubt an adaptive _movement_; but is there any occasion +upon which the reflex mechanism concerned therein can ever have been of +adaptive _use_? Until a man's legs have been paralyzed as to their +voluntary motion, he will always promptly withdraw his feet from any +injurious source of irritation by means of his conscious intelligence. +True, the reflex mechanism secures an almost inappreciable saving in the +time of response to a stimulus, as compared with the time required for +response by an act of will; but the difference is so exceedingly small, +that we can hardly suppose the saving of it in this particular case to +be a matter of any adaptive--much less selective--importance. Nor is it +more easy to suppose that the reflex mechanism has been developed by +natural selection for the purpose of replacing voluntary action when the +latter has been destroyed or suspended by grave spinal injury, +paralysis, coma, or even ordinary sleep. In short, even if for the sake +of argument we allow it to be conceivable that any single human being, +ape, or still more distant ancestor, has ever owed its life to the +possession of this mechanism, we may still be certain that not one in a +million can have done so. And, if this is the case with regard to the +mechanism as now fully constructed, still more must it have been the +case with regard to all the previous stages of construction. For here, +without elaborating the point, it would appear that a process of +construction by survival of the fittest alone is incomprehensible. + +On the other hand, of course, the theory of use-inheritance furnishes a +fully intelligible--whether or not a true--explanation. For those +nerve-centres in the spinal cord which co-ordinate the muscles required +for retracting the feet are the centres used by the will for this +purpose. And, by hypothesis, the frequent use of them for this purpose +under circumstances of stimulation which render the muscular response +appropriate, will eventually establish an organic connexion between such +response and the kind of stimulation to which it is appropriate--even +though there be no utilitarian reason for its establishment[43]. To +invert a phrase of Aristotle, we do not frequently use this mechanism +because we have it (seeing that in our normal condition there is no +necessity for such use); but, by hypothesis, we have it because we have +frequently used its several elements in appropriate combination. + + [43] It may be said, with regard to this particular reflex, that it + may perhaps be, so to speak, a mechanical accident, arising + from the contiguity of the sensory and motor roots in the cord. + But as this suggestion cannot apply to other reflexes presently + to be adduced, it need not be considered. + +I will adduce but one further example in illustration of these general +principles--passing at once from the foregoing case of comparative +simplicity to one of extreme complexity. + +There is a well-known experiment on a brainless frog, which reveals a +beautiful reflex mechanism in the animal, whereby the whole body is +enabled continually to readjust its balance on a book (or any other +plane surface), as this is slowly rotated on a horizontal axis. So long +as the book is lying flat, the frog remains motionless; but as soon as +the book is tilted a little, so that the frog is in danger of slipping +off, all the four feet begin to crawl up the hill; and the steeper the +hill becomes, the faster they crawl. When the book is vertical, the frog +has reached the now horizontal back, and so on. Such being the facts, +the question is--How can the complicated piece of machinery thus implied +have been developed by natural selection? Obviously it cannot have been +so by any of the parts concerned having been originally distributed +among different individuals, and afterwards united in single individuals +by survival (i.e. free intercrossing) of the fittest. In other words, +the case is obviously one of co-adaptation, and not one of the blending +of adaptations. Again, and no less obviously, it is impossible that the +co-adaptation can have been _gradually developed_ by natural selection, +because, in order to have been so, it must by hypothesis have been of +some degree of use in every one of its stages; yet it plainly cannot +have been until it had been fully perfected in all its astonishing +complexity[44]. + + [44] Of course it will be observed that the question is not with + regard to the development of all the nerves and muscles + concerned in this particular process. It is as to the + development of the co-ordinating centres, which thus so + delicately respond to the special stimuli furnished by + variations of angle to the horizon. And it is as inconceivable + in this case of reflex action, as it is in almost every other + case of reflex action, that the highly specialized machinery + required for performing the adaptive function can ever have had + its origin in the performance of any other function. Indeed, a + noticeable peculiarity of reflex mechanisms as a class is the + highly specialized character of the functions which their + highly organized structures subserve. + +Lastly, not only does it thus appear impossible that during all stages +of its development--or while as yet incapable of performing its +intricate function--this nascent mechanism can have had any adaptive +value; but even as now fully developed, who will venture to maintain +that it presents any selective value? As long as the animal preserves +its brain, it will likewise preserve its balance, by the exercise of its +intelligent volition. And, if the brain were in some way destroyed, the +animal would be unable to breed, or even to feed; so that natural +selection can never have had any _opportunity_, so to speak, of +developing this reflex mechanism in brainless frogs. On the other hand, +as we have just seen, we cannot perceive how there can ever have been +any _raison d'etre_ for its development in normal frogs--even if its +development were conceivably possible by means of this agency. But if +practice makes perfect in the race, as it does in the individual, we can +immediately perceive that the constant habit of correctly adjusting its +balance may have gradually developed, in the batrachian organization, +this non-necessary reflex[45]. + + [45] We meet with a closely analogous reflex mechanism in brainless + vertebrata of other kinds; but these do not furnish such good + test cases, because the possibility of natural selection cannot + be so efficiently attenuated. The perching of brainless birds, + for instance, at once refers us to the roosting of sleeping + birds, where the reflex mechanism concerned is clearly of high + adaptive value. Therefore such a case is not available as a + test, although the probability is that birds have inherited + their balancing mechanisms from their sauropsidian ancestors, + where it would have been of no such adaptive importance. + +And, of course, this example--like that of withdrawing the feet from a +source of stimulation, which a frog will do as well as a man--does not +stand alone. Without going further a-field than this same animal, any +one who reads, from our present point of view, Goltz's work on the +reflex actions of the frog, will find that the great majority of +them--complex and refined though most of them are--cannot conceivably +have ever been of any use to any frog that was in undisturbed possession +of its brain. + +Hence, not to occupy space with a reiteration of facts all more or less +of the same general kind, and therefore all presenting identical +difficulties to ultra-Darwinian theory, I shall proceed to give two +others which appear to me of particular interest in the present +connexion, because they furnish illustrations of reflex actions in a +state of only partial development, and are therefore at the present +moment demonstrably useless to the animal which displays them. + +Many of our domesticated dogs, when we gently scratch their sides and +certain other parts of the body, will themselves perform scratching +movements with the hind leg of the same side as that upon which the +irritation is being supplied. According to Goltz[46], this action is a +true reflex; for he found that it is performed equally well in a dog +which has been deprived of its cerebral hemispheres, and therefore of +its normal volition. Again, according to Haycraft[47], this reflex is +congenital, or not acquired during the life-time of each individual dog. +Now, although the action of scratching is doubtless adaptive, it appears +to me incredible that it could ever have become organized into a +congenital reflex by natural selection. For, in order that it should, +the scratching away fleas would require to have been a function of +selective value. Yet, even if the irritation caused by fleas were +supposed to be so far fatal in the struggle for existence, it is certain +that they would always be scratched away by the conscious intelligence +of each individual dog; and, therefore, that no advantage could be +gained by organizing the action into a reflex. On the other hand, if +acquired characters are ever in any degree transmitted, it is easy to +understand how so frequently repeated an action should have become, in +numberless generations of dogs, congenitally automatic. + + [46] _Pflueger's Archiv_, Bd. xx. s. 23 (1879). + + [47] _Brain_, part xlviii, pp. 516-19 (1889).--There is still better + proof of this in the case of certain rodents. For instance, + observing that rats and mice are under the necessity of very + frequently scratching themselves with their hind-feet, I tried + the experiment of removing the latter from newly-born + individuals--i.e. before the animals were able to co-ordinate + their movements, and therefore before they had ever even + attempted to scratch themselves. Notwithstanding that they were + thus destitute of individual experience with regard to the + benefit of scratching, they began their scratching movements + with their stumps as soon as they were capable of executing + co-ordinated movements, and afterwards continued to do so till + the end of their lives with as much vigour and frequency as + unmutilated animals. Although the stumps could not reach the + seats of irritation which were bent towards them, they used to + move rapidly in the air for a time sufficient to have given the + itching part a good scratch, had the feet been present--after + which the animals would resume their sundry other avocations + with apparent satisfaction. These facts showed the hereditary + response to irritation by parasites to be so strong, that even + a whole life-time's experience of its futility made no + difference in the frequency or the vigour thereof. + +So much for the general principle of selective value as applied to this +particular case. And similarly, of course, we might here repeat the +application of all the other general principles, which have just been +applied in the two preceding cases. But it is only one of these other +general principles which I desire in the present case specially to +consider, for the purpose of considering more closely than hitherto the +difficulty which this principle presents to ultra-Darwinian theory. + +The difficulty to which I allude is that of understanding how all the +stages in the _development_ of a reflex action can have been due to +natural selection, seeing that, before the reflex mechanism has been +sufficiently elaborated to perform its function, it cannot have +presented any degree of utility. Now the particular force of the present +example, the action of scratching--as also of the one to +follow--consists in the fact that it is a case where a reflex action is +not yet completely organized. It appears to be only in course of +construction, so that it is neither invariably present, nor, when it is +present, is it ever fully adapted to the performance of its function. + +That it is not invariably present (when the brain is so) may be proved +by trying the simple experiment on a number of puppies--and also of +full-grown dogs. Again, that even when it is present it is far from +being fully adapted to the performance of its function, may be proved by +observing that only in rare instances does the scratching leg succeed in +scratching the place which is being irritated. The movements are made +more or less at random, and as often as not the foot fails to touch the +body at any place at all. Hence, although we have a "prophecy" of a +reflex action well designed for the discharge of a particular function, +at present the machinery is not sufficiently perfected for the adequate +discharge of that function. In this important respect it differs from +the otherwise closely analogous reflex action of the frog, whereby the +foot of the hind leg is enabled to localize with precision a seat of +irritation on the side of the body. But this beautiful mechanism in the +frog cannot have sprung into existence ready formed at any historical +moment in the past history of the phyla. It must have been the subject +of a more or less prolonged evolution, in some stage of which it must +presumably have resembled the now nascent scratching reflex of the dog, +in making merely abortive attempts at localizing the seat of +irritation--supposing, of course, that some physiologist had been there +to try the experiment by first removing the brain. Now, even if one +could imagine it to be, either in the frog or in the dog, a matter of +selective importance that so exceedingly refined a mechanism should have +been developed for the sole purpose of inhibiting the bites of +parasites--which in every normal animal would certainly be discharged by +an _intentional_ performance of the movements in question,--even if, in +order to save an hypothesis at all costs, we make so violent a +supposition as this, still we should do so in vain. For it would still +remain undeniably certain that the reflex mechanism is _not_ of any +selective value. Even now the mechanism in the dog is not sufficiently +precise to subserve the only function which occasionally and abortively +it attempts to perform. Thus it has all the appearance of being but an +imitating shadow of certain neuro-muscular adjustments, which have been +habitually performed in the canine phyla by a volitional response to +cutaneous irritation. Were it necessary, this argument might be +strengthened by observing that the reflex action is positively +_improved_ by removal of the brain. + +The second example of a nascent reflex in dogs which I have to mention +is as follows. + +Goltz found that his brainless dogs, when wetted with water, would shake +themselves as dry as possible, in just the same way as normal dogs will +do under similar circumstances. This, of course, proves that the shaking +movements may be performed by a reflex mechanism, which can have no +other function to perform in the organization of a dog, and which, +besides being of a highly elaborate character, will respond only to a +very special kind of stimulation. Now, here also I find that the +mechanism is congenital, or not acquired by individual experience. For +the puppies on which I experimented were kept indoors from the time of +their birth--so as never to have had any experience of being wetted by +rain, &c.--till they were old enough to run about with a full power of +co-ordinating their general movements. If these young animals were +suddenly plunged into water, the shock proved too great: they would +merely lie and shiver. But if their feet alone were wetted, by being +dipped in a basin of water, the puppies would soon afterwards shake +their heads in the peculiar manner which is required for shaking water +off the ears, and which in adult dogs constitutes the first phase of a +general shaking of the whole body. + +Here, then, we seem to have good evidence of all the same facts which +were presented in the case of the scratching reflex. In the first +place, co-adaptation is present in a very high degree, because this +shaking reflex in the dog, unlike the skin-twitching reflex in the +horse, does not involve only a single muscle, or even a single group of +muscles; it involves more or less the co-ordinated activity of many +voluntary muscles all over the body. Such, at any rate, is the case when +the action is performed by the intelligent volition of an adult dog; and +if a brainless dog, or a young puppy, does not perform it so extensively +or so vigorously, this only goes to prove that the reflex has not yet +been sufficiently developed to serve as a substitute for intelligent +volition--i.e. that it is _useless_, or a mere organic shadow of the +really adaptive substance. Again, even if this nascent reflex had been +so far developed as to have been capable of superseding voluntary +action, still we may fairly doubt whether it could have proved of +selective value. For it is questionable whether the immediate riddance +of water after a wetting is a matter of life and death to dogs in a +state of nature. Moreover, even if it were, every individual dog would +always have got rid of the irritation, and so of the danger, by means of +a _voluntary_ shake--with the double result that natural selection has +never had any opportunity of gradually building up a special reflex +mechanism for the purpose of securing a shake, and that the canine race +have not had to wait for any such unnecessary process. Lastly, such a +process, besides being unnecessary, must surely have been, under any +circumstances, impossible. For even if we were to suppose--again for the +sake of saving an hypothesis at any cost--that the presence of a +fully-formed shaking reflex is of selective value in the struggle for +existence, it is perfectly certain that all the stages through which the +construction of so elaborate a mechanism must have passed could not have +been, under any circumstances, of any such value. + +But, it is needless to repeat, according to the hypothesis of +use-inheritance, there is no necessity to suppose that these incipient +reflex mechanisms _are_ of any value. If function produces structure in +the race as it does in the individual, the voluntary and frequently +repeated actions of scratching and shaking may very well have led to an +organic integration of the neuro-muscular mechanisms concerned. Their +various parts having been always co-ordinated for the performance of +these actions by the intelligence of innumerable dogs in the past, their +co-adapted activity in their now automatic responses to appropriate +stimuli presents no difficulty. And the consideration that neither in +their prospectively more fully developed condition, nor, _a fortiori_, +in their present and all previous stages of evolution, can these reflex +mechanisms be regarded as presenting any selective--or even so much as +any adaptive--value, is neither more nor less than the theory of +use-inheritance would expect. + +Thus, with regard to the phenomena of reflex action in general, all the +facts are such as this theory requires, while many of the facts are such +as the theory of natural selection alone cannot conceivably explain. +Indeed, it is scarcely too much to say, that most of the facts are such +as directly contradict the latter theory in its application to them. +But, be this as it may, at present there are only two hypotheses in the +field whereby to account for the facts of adaptive evolution. One of +these hypotheses is universally accepted, and the only question is +whether we are to regard it as _alone_ sufficient to explain _all_ the +facts. The other hypothesis having been questioned, we can test its +validity only by finding cases which it is fully capable of explaining, +and which do not admit of being explained by its companion hypothesis. I +have endeavoured to show that we have a large class of such cases in the +domain of reflex action, and shall next endeavour to show that there is +another large class in the domain of instinct. + + * * * * * + +If instinct be, as Professor Hering, Mr. Samuel Butler, and others have +argued, "hereditary habit"--i. e. if it comprises an element of +transmitted experience--we at once find a complete explanation of many +cases of the display of instinct which otherwise remain inexplicable. +For although a large number--or even, as I believe, a large majority--of +instincts are explicable by the theory of natural selection alone, or by +supposing that they were gradually developed by the survival of +fortuitous variations in the way of advantageous psychological +peculiarities, this only applies to comparatively simple instincts, such +as that of a protectively coloured animal exhibiting a preference for +the surroundings which it resembles, or even adopting attitudes in +imitation of objects which occur in such surroundings. But in all cases +where instincts become complex and refined, we seem almost compelled to +accept Darwin's view that their origin is to be sought in consciously +intelligent adjustments on the part of ancestors. + +Thus, to give only one example, a species of Sphex preys upon +caterpillars, which it stings in their nerve-centres for the purpose of +paralyzing, without killing them. The victims, when thus rendered +motionless, are then buried with the eggs of the Sphex, in order to +serve as food for her larvae which subsequently develop from these eggs. +Now, in order thus to paralyze a caterpillar, the Sphex has to sting it +successively in nine minute and particular points along the ventral +surface of the animal--and this the Sphex unerringly does, to the +exclusion of all other points of the caterpillar's anatomy. Well, such +being the facts--according to M. Fabre, who appears to have observed +them carefully--it is conceivable enough, as Darwin supposed[48], that +the ancestors of the Sphex, being like many other hymenopterous insects +highly intelligent, should have observed that on stinging caterpillars +in these particular spots a greater amount of effect was produced than +could be produced by stinging them anywhere else; and, therefore, that +they habitually stung the caterpillars in these places only, till, in +course of time, this originally intelligent habit became by heredity +instinctive. But now, on the other hand, if we exclude the possibility +of this explanation, it appears to me incredible that such an instinct +should ever have been evolved at all; for it appears to me incredible +that natural selection, unaided by originally intelligent action, could +ever have developed such an instinct out of merely fortuitous +variations--there being, by hypothesis, nothing to _determine_ +variations of an insect's mind in the direction of stinging caterpillars +only in these nine intensely localized spots[49]. + + [48] For details of his explanation of this particular case, for + which I particularly inquired, see _Mental Evolution in + Animals_, pp. 301-2. + + [49] Note B. + +Again, there are not a few instincts which appear to be wholly useless +to their possessors, and others again which appear to be even +deleterious. The dusting over of their excrement by certain +freely-roaming carnivora; the choice by certain herbivora of particular +places on which to void their urine, or in which to die; the howling of +wolves at the moon; purring of cats, &c., under pleasurable emotion; and +sundry other hereditary actions of the same apparently unmeaning kind, +all admit of being readily accounted for as useless habits originally +acquired in various ways, and afterwards perpetuated by heredity, +because not sufficiently deleterious to have been stamped out by natural +selection[50]. But it does not seem possible to explain them by survival +of the fittest in the struggle for existence. + + [50] For fuller treatment see _Mental Evolution in Animals_, pp. + 274-285, 378-379, 381-383. + +Finally, in the case of our own species, it is self-evident that the +aesthetic, moral, and religious instincts admit of a natural and easy +explanation on the hypothesis of use-inheritance, while such is by no +means the case if that hypothesis is rejected. Our emotions of the +ludicrous, of the beautiful, and of the sublime, appear to be of the +nature of hereditary instincts; and be this as it may, it would further +appear that, whatever else they may be, they are certainly not of a +life-preserving character. And although this cannot be said of the +moral sense when the theory of natural selection is extended from the +individual to the tribe, still, when we remember the extraordinary +complexity and refinement to which they have attained in civilized man, +we may well doubt whether they can have been due to natural selection +alone. But space forbids discussion of this large and important question +on the present occasion. Suffice it therefore to say, that I doubt not +Weismann himself would be the first to allow that his theory of heredity +encounters greater difficulties in the domain of ethics than in any +other--unless, indeed, it be that of religion[51]. + + [51] For an excellent essay on the deleterious character of early + forms of religion from a biological point of view, see the Hon. + Lady Welby, _An Apparent Paradox in Mental Evolution_ (Journ. + Anthrop. Inst. May 1891). + + * * * * * + +I have now given a brief sketch of the indirect evidence in favour of +the so-called Lamarckian factors, in so far as this appears fairly +deducible from the facts of reflex action and of instinct. It will now +be my endeavour to present as briefly what has to be said against this +evidence. + +As previously observed, the facts of reflex action have not been +hitherto adduced in the present connexion. This has led me to occupy +considerably more space in the treatment of them than those of instinct. +On this account, also, there is here nothing to quote, or to consider, +_per contra_. On the other hand, however, Weismann has himself dealt +with the phenomena of instinct in animals, though not, I think, in +man--if we except his brilliant essay on music. Therefore let us now +begin this division of our subject by briefly stating, and considering, +what he has said upon the subject. + +The answer of Weismann to difficulties which arise against the +ultra-Darwinian theory in the domain of instinct, is as follows:-- + + "The necessity for extreme caution in appealing to the supposed + hereditary effects of use, is well shown in the case of those + numerous instincts which only come into play once in a life-time, + and which do not therefore admit of improvement by practice. The + queen-bee takes her nuptial flight only once, and yet how many and + complex are the instincts and the reflex mechanisms which come into + play on that occasion. Again, in many insects the deposition of + eggs occurs but once in a life-time, and yet such insects always + fulfil the necessary conditions with unfailing accuracy[52]." + + [52] _Essays_, i. p. 93. + +But in this rejoinder the possibility is forgotten, that although such +actions are _now_ performed only once in the individual life-time, +_originally_--i.e. when the instincts were being developed in a remote +ancestry--they may have been performed on many frequent and successive +occasions during the individual life-time. In all the cases quoted by +Weismann, instincts of the kind in question bear independent evidence of +high antiquity, by occurring in whole genera (or even families), by +being associated with peculiar and often highly evolved structures +required for their performance, and so on. Consequently, in these cases +ample time has been allowed for subsequent changes of habit, and of +seasonal alterations with respect to propagation--both these things +being of frequent and facile occurrence among animals of all kinds, even +within periods which fall under actual observation. Nevertheless, I do +not question that there are instinctive activities which, as far as we +are able to see, can never have been performed more than once in each +individual life-time[53]. The fact, however, only goes to show what is +fully admitted--that some instincts (and even highly complex instincts) +have apparently been developed by natural selection alone. Which, of +course, is not equivalent to showing that all instincts must have been +developed by natural selection alone. The issue is not to be debated on +general grounds like this, but on those of particular cases. Even if it +were satisfactorily proved that the instincts of a queen-bee have been +developed by natural selection, it would not thereby be proved that such +has been the case with the instincts of a Sphex wasp. One can very well +understand how the nuptial flight of the former, with all its associated +actions, may have been brought about by natural selection alone; but +this does not help us to understand how the peculiar instincts of the +latter can have been thus caused. + + [53] See _Mental Evolution in Animals_, pp. 377-8. + +Strong evidence in favour of Weismann's views does, however, at first +sight seem to be furnished by social hymenoptera in other respects. For +not only does the queen present highly specialized and altogether +remarkable instincts; but the neuters present totally different and even +still more remarkable instincts--which, moreover, are often divided into +two or more classes, corresponding with the different "castes." Yet the +neuters, being barren females, never have an opportunity of bequeathing +their instincts to progeny. Thus it appears necessary to suppose that +the instincts of all the different castes of neuters are latent in the +queen and drones, together with the other instincts which are patent in +both. Lastly, it seems necessary to suppose that all this wonderful +organization of complex and segregated instincts must have been built up +by natural selection acting exclusively on the queens and drones--seeing +that these exercise their own instincts only once in a life-time, while, +as just observed, the neuters cannot possibly bequeath their individual +experience to progeny. Obviously, however, natural selection must here +be supposed to be operating at an immense disadvantage; for it must have +built up the often diverse and always complex instincts of neuters, not +directly, but indirectly through the queens and drones, which never +manifest any of these instincts themselves. + +Now Darwin fully acknowledged the difficulty of attributing these +results to the unaided influence of natural selection; but the fact of +neuter insects being unable to propagate seemed to him to leave no +alternative. And so it seems to Weismann, who accordingly quotes these +instincts in support of his views. And so it seemed to me, until my work +on _Animal Intelligence_ was translated into French, and an able Preface +was supplied to that translation by M. Perrier. In this Preface it is +argued that we are not necessarily obliged to exclude the possibility of +Lamarckian principles having operated in the original formation of these +instincts. On the contrary, if such principles ever operate at all, +Perrier shows that here we have a case where it is virtually certain +that they must have operated. For although neuter insects are now unable +to propagate, their organization indicates--if it does not actually +prove--that they are descended from working insects which were able to +propagate. Thus, in all probability, what we now call a "hive" was +originally a society of sexually mature insects, all presenting the same +instincts, both as to propagation and to co-operation. When these +instincts, thus common to all individuals composing the hive, had been +highly perfected, it became of advantage in the struggle for existence +(between different hives or communities) that the functions of +reproduction should devolve more upon some individuals, while those of +co-operation should devolve more upon others. Consequently, this +division of labour began, and gradually became complete, as we now find +it in bees and ants. Perrier sustains the hypothesis thus briefly +sketched by pointing to certain species of social hymenoptera where we +may actually observe different stages of the process--from cases where +all the females of the hive are at the same time workers and breeders, +up to the cases where the severance between these functions has become +complete. Therefore, it seems to me, it is no longer necessary to +suppose that in these latter cases all the instincts of the (now) barren +females can only have been due to the unaided influence of natural +selection. + +Nevertheless, although I think that Perrier has made good his position +thus far, that his hypothesis fails to account for some of the instincts +which are manifested by neuter insects, such as those which, so far as I +can see, must necessarily be supposed to have originated after the +breeding and working functions had become separated--seeing that they +appear to have exclusive reference to this peculiar state of matters. +Possibly, however, Perrier might be able to meet each of these +particular instincts, by showing how they could have arisen out of +simpler beginnings, prior to the separation of the two functions in +question. There is no space to consider such possibilities in detail; +but, until this shall have been done, I do not think we are entitled to +conclude that the phenomena of instinct as presented by neuter insects +are demonstrably incompatible with the doctrines of Lamarck--or, that +these phenomena are available as a logical proof of the unassisted +agency of natural selection in the case of instincts in general[54]. + + [54] [See H. Spencer, _The Inadequacy of Natural Selection, A + Rejoinder to Professor Weismann_, Contemp. Rev. 1893; and + _Weismannism once more_, Ibid. Oct. 1894; Weismann, _The + All-sufficiency of Natural Selection_, Ibid. 1893; and _The + Effect of External Influences upon Development_, "Romanes + Lecture" 1894: also _Neuter Insects and Lamarckism_, W. Platt + Ball, Natural Science, Feb. 1894, and _Neuter Insects and + Darwinism_, J. T. Cunningham, Ibid. April 1894. C. Ll. M.] + + +(B.) +_Inherited Effects of Use and of Disuse._ + +There is no doubt that Darwin everywhere attaches great weight to this +line of evidence. Nevertheless, in my opinion, there is equally little +doubt that, taken by itself, it is of immeasurably less weight than +Darwin supposed. Indeed, I quite agree with Weismann that the whole of +this line of evidence is practically worthless; and for the following +reasons. + +The evidence on which Darwin relied to prove the inherited effects of +use and disuse was derived from his careful measurements of the increase +or decrease which certain bones of our domesticated animals have +undergone, as compared with the corresponding bones of ancestral stocks +in a state of nature. He chose domesticated animals for these +investigations, because, while yielding unquestionable cases of +increased or diminished use of certain organs over a large number of +sequent generations, the results were not complicated by the possible +interference of natural selection on the one hand, or by that of the +economy of nutrition on the other. For "with highly-fed domesticated +animals there seems to be no economy of growth, or any tendency to the +elimination of superfluous details[55];" seeing that, among other +considerations pointing in the same direction, "structures which are +rudimentary in the parent species, sometimes become partially +re-developed in our domesticated productions[56]." + + [55] _Variation of Plants and Animals_, vol. ii. p. 289. + + [56] _Ibid._ p. 346. + +The method of Darwin's researches in this connexion was as follows. +Taking, for example, the case of ducks, he carefully weighed and +measured the wing-bones and leg-bones of wild and tame ducks; and he +found that the wing-bones were smaller, while the leg-bones were larger, +in the tame than in the wild specimens. These facts he attributed to +many generations of tame ducks using their wings less, and their legs +more, than was the case with their wild ancestry. Similarly he compared +the leg-bones of wild rabbits with those of tame ones, and so forth--in +all cases finding that where domestication had led to increased use of a +part, that part was larger than in the wild parent stock; while the +reverse was the case with parts less used. Now, although at first sight +these facts certainly do seem to yield good evidence of the inherited +effects of use and disuse, they are really open to the following very +weighty objections. + +First of all, there is no means of knowing how far the observed effects +may have been due to increased or diminished use during only the +individual life-time of each domesticated animal. Again, and this is a +more important point, in all Darwin's investigations the increase or +decrease of a part was estimated, not by directly comparing, say the +wing-bones of a domesticated duck with the wing-bones of a wild duck, +but by comparing the _ratio_ between the wing and leg bones of a tame +duck with the _ratio_ between the wing and leg bones of a wild duck. +Consequently, if there be any reason to doubt the supposition that a +really inherited decrease in the size of a part thus estimated is due to +the inherited effects of disuse, such a doubt will also extend to the +evidence of increased size being due to the inherited effects of use. +Now there is the gravest possible doubt lying against the supposition +that any really inherited decrease in the size of a part is due to the +inherited effects of disuse. For it may be--and, at any rate to some +extent, must be--due to another principle, which it is strange that +Darwin should have overlooked. This is the principle which Weismann has +called Panmixia, and which cannot be better expressed than in his own +words:-- + + "A goose or a duck must possess strong powers of flight in the + natural state, but such powers are no longer necessary for + obtaining food when it is brought into the poultry-yard; so that a + rigid selection of individuals with well-developed wings at once + ceases among its descendants. Hence, in the course of generations, + a deterioration of the organs of flight must necessarily + ensue[57]." + + [57] _Essays_, i. p. 90. + +Or, to state the case in another way: if any structure which was +originally built up by natural selection on account of its use, ceases +any longer to be of so much use, in whatever degree it ceases to be of +use, in that degree will the premium before set upon it by natural +selection be withdrawn. And the consequence of this withdrawal of +selection as regards that particular part will be to allow the part to +degenerate in successive generations. Such is the principle which +Weismann calls Panmixia, because, by the withdrawal of selection from +any particular part, promiscuous breeding ensues with regard to that +part. And it is easy to see that this principle must be one of very +great importance in nature; because it must necessarily come into +operation in all cases where any structure or any instinct has, through +any change in the environment or in the habits of a species, ceased to +be useful. It is likewise easy to see that its effect must be the same +as that which was attributed by Darwin to the inherited effect of +disuse; and, therefore, that the evidence on which he relied in proof of +the inherited effects both of use and of disuse is vitiated by the fact +that the idea of Panmixia did not occur to him. + +Here, however, it may be said that the idea first occurred to me[58] +just after the publication of the last edition of the _Origin of +Species_. I called the principle the Cessation of Selection--which I +still think a better, because a more descriptive, term than Panmixia; +and at that time it appeared to me, as it now appears to Weismann, +entirely to supersede the necessity of supposing that the effect of +disuse is ever inherited in any degree at all. Thus it raised the whole +question as to the admissibility of Lamarckian principles in general; or +the question on which we are now engaged touching the possible +inheritance of acquired, as distinguished from congenital, characters. +But on discussing the matter with Mr. Darwin, he satisfied me that the +larger question was not to be so easily closed. That is to say, although +he fully accepted the principle of the Cessation of Selection, and as +fully acknowledged its obvious importance, he convinced me that there +was independent evidence for the transmission of acquired characters, +sufficient in amount to leave the general structure of his previous +theory unaffected by what he nevertheless recognized as a factor which +must necessarily be added. All this I now mention in order to show that +the issue which Weismann has raised since Darwin's death was expressly +contemplated during the later years of Darwin's life. For if the idea of +Panmixia--in the absence of which Weismann's entire system would be +impossible--had never been present to Darwin's mind, we should have been +left in uncertainty how he would have regarded this subsequent revolt +against what are generally called the Lamarckian principles[59]. + + [58] _Nature_, vol. ix. pp. 361-2, 440-1; and vol. x. p. 164. + + [59] Appendix I. + +Moreover, in this connexion we must take particular notice that the +year after I had published these articles on the Cessation of Selection, +and discussed with Mr. Darwin the bearing of this principle on the +question of the transmission of acquired characters, Mr. Galton followed +with his highly important essay on Heredity. For in this essay Mr. +Galton fully adopted the principle of the Cessation of Selection, and +was in consequence the first publicly to challenge the Lamarckian +principles--pointing out that, if it were thus possible to deny the +transmission of acquired characters _in toto_, "we should be relieved +from all further trouble"; but that, if such characters are transmitted +"in however faint a degree, a complete theory of heredity must account +for them." Thus the question which, in its revived condition, is now +attracting so much attention, was propounded in all its parts some +fifteen or sixteen years ago; and no additional facts or new +considerations of any great importance bearing upon the subject have +been adduced since that time. In other words, about a year after my own +conversations with Mr. Darwin, the whole matter was still more +effectively brought before his notice by his own cousin. And the result +was that he still retained his belief in the Lamarckian factors of +organic evolution, even more strongly than it was retained either by Mr. +Galton or myself[60]. + + [60] For a fuller statement of Mr. Galton's theory of Heredity, and + its relation to Weismann's, see _An Examination of + Weismannism_. + +We have now considered the line of evidence on which Darwin chiefly +relied in proof of the transmissibility of acquired characters; and it +must be allowed that this line of evidence is practically worthless. +What he regarded as the inherited effects of use and of disuse may be +entirely due to the cessation of selection in the case of our +domesticated animals, combined with an active _reversal_ of selection in +the case of natural species. And in accordance with this view is the +fact that the degeneration of disused parts proceeds much further in the +case of wild species than it does in that of domesticated varieties. For +although it may be said that in the case of wild species more time has +been allowed for a greater accumulation of the inherited effects of +disuse than can have been the case with domesticated varieties, the +alternative explanation is at least as probable--that in the case of +wild species the merely negative, or passive, influence of the +_cessation_ of selection has been continuously and powerfully assisted +by the positive, or active, influence of the _reversal_ of selection, +through economy of growth and the general advantage to be derived from +the abolition of useless parts[61]. + + [61] For a fuller explanation of the important difference between + the mere cessation and the actual reversal of selection, see + Appendix I. + +The absence of any good evidence of this direct kind in favour of +use-inheritance will be rendered strikingly apparent to any one who +reads a learned and interesting work by Professor Semper[62]. His object +was to show the large part which he believed to have been played by +external conditions of life in directly modifying organic types--or, in +other words, of proving that side of Lamarckianism which refers to the +immediate action of the environment, whether with or without the +co-operation of use-inheritance and natural selection. Although Semper +gathered together a great array of facts, the more carefully one reads +his book the more apparent does it become that no single one of the +facts is in itself conclusive evidence of the transmission to progeny of +characters which are acquired through use-inheritance or through direct +action of the environment. Every one of the facts is susceptible of +explanation on the hypothesis that the principle of natural selection +has been the only principle concerned. This, however, it must be +observed, is by no means equivalent to proving that characters thus +acquired are not transmitted. As already pointed out, it is +impracticable with species in a state of nature to dissociate the +distinctively Darwinian from the possibly Lamarckian factors; so that +even if the latter are largely operative, we can only hope for direct +evidence of the fact from direct experiments on varieties in a state of +domestication. To this branch of our subject, therefore, we will now +proceed. + + [62] _Animal Life_, International Scientific Series, vol. xxxi. + + + + +CHAPTER IV. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(C.) +_Experimental Evidence in favour of the Inheritance of Acquired +Characters._ + + +Notwithstanding the fact already noticed, that no experiments have +hitherto been published with reference to the question of the +transmission of acquired characters[63], there are several researches +which, with other objects in view, have incidentally yielded seemingly +good evidence of such transmission. The best-known of these +researches--and therefore the one with which I shall begin--is that of +Brown-Sequard touching the effects of certain injuries of the nervous +system in guinea-pigs. + + [63] The experiments of Galton and Weismann upon this subject are + nugatory, as will be shown later on. But since the above was + written an important research has been published by Mr. + Cunningham, of the Marine Biological Association. For a full + account I must refer the reader to his forthcoming paper in the + _Philosophical Transactions_. The following is his own + statement of the principal results:-- + + "A case which I have myself recently investigated + experimentally seems to me to support very strongly the theory + of the inheritance of acquired characters, I have shown that in + normal flat-fishes, if the lower side be artificially exposed + to light for a long time, pigmentation is developed on that + side; but when the exposure is commenced while the specimens + are still in process of metamorphosis, when pigment-cells are + still present on the lower side, the action of light does not + prevent the disappearance of these pigment-cells. They + disappear as in individuals living under normal conditions, but + after prolonged exposure pigment-cells reappear. The first fact + proves that the disappearance of the pigment-cells from the + lower side in the metamorphosis is an hereditary character, and + not a change produced in each individual by the withdrawal of + the lower side from the action of light. On the other hand, the + experiments show that the absence of pigment-cells from the + lower side throughout life is due to the fact that light does + not act upon that side, for, when it is allowed to act, + pigment-cells appear. It seems to me the only reasonable + conclusion from these facts is, that the disappearance of + pigment-cells was originally due to the absence of light, and + that this change has now become hereditary. The pigment-cells + produced by the action of light on the lower side are in all + respects similar to those normally present on the upper side of + the fish. If the disappearance of the pigment-cells were due + entirely to a variation of the germ-plasm, no external + influence could cause them to reappear, and, on the other hand, + if there were no hereditary tendency, the colouration of the + lower side of the flat-fish when exposed would be rapid and + complete."--_Natural Science_, Oct. 1893. + +During a period of thirty years Brown-Sequard bred many thousands of +guinea-pigs as material for his various researches; and in those whose +parents had not been operated upon in the ways to be immediately +mentioned, he never saw any of the peculiarities which are about to be +described. Therefore the hypothesis of coincidence, at all events, must +be excluded. The following is his own summary of the results with which +we are concerned:-- + + 1st. Appearance of epilepsy in animals born of parents which had + been rendered epileptic by an injury to the spinal cord. + + 2nd. Appearance of epilepsy also in animals born of parents which + had been rendered epileptic by section of the sciatic nerve. + + 3rd. A change in the shape of the ear in animals born of parents in + which such a change was the effect of a division of the cervical + sympathetic nerve. + + 4th. Partial closure of the eyelids in animals born of parents in + which that state of the eyelids had been caused either by section + of the cervical sympathetic nerve, or the removal of the superior + cervical ganglion. + + 5th. Exophthalmia in animals born of parents in which an injury to + the restiform body had produced that protrusion of the eyeball. + This interesting fact I have witnessed a good many times, and seen + the transmission of the morbid state of the eye continue through + four generations. In these animals, modified by heredity, the two + eyes generally protruded, although in the parents usually only one + showed exophthalmia, the lesion having been made in most cases only + on one of the corpora restiformia. + + 6th. Haematoma and dry gangrene of the ears in animals born of + parents in which these ear-alterations had been caused by an injury + to the restiform body near the nib of the calamus. + + 7th. Absence of two toes out of the three of the hind leg, and + sometimes of the three, in animals whose parents had eaten up their + hind-leg toes which had become anaesthetic from a section of the + sciatic nerve alone, or of that nerve and also of the crural. + Sometimes, instead of complete absence of the toes, only a part of + one or two or three was missing in the young, although in the + parent not only the toes but the whole foot were absent (partly + eaten off, partly destroyed by inflammation, ulceration, or + gangrene.) + + 8th. Appearance of various morbid states of the skin and hair of + the neck and face in animals born of parents having had similar + alterations in the same parts, as effects of an injury to the + sciatic nerve. + +These results[64] have been independently vouched for by two of +Brown-Sequard's former assistants--Dr. Dupuy, and the late Professor +Westphal. Moreover, his results with regard to epilepsy have been +corroborated also by Obersteiner[65]. I may observe, in passing, that +this labour of testing Brown-Sequard's statements is one which, in my +opinion, ought rather to have been undertaken, if not by Weismann +himself, at all events by some of his followers. Both he and they are +incessant in their demand for evidence of the transmission of acquired +characters; yet they have virtually ignored the foregoing very +remarkable statements. However, be this as it may, all that we have now +to do is to consider what the school of Weismann has had to say with +regard to these experiments on the grounds of general reasoning which +they have thus far been satisfied to occupy. + + [64] For Professor Weismann's statement of and discussion of these + results see _Essays_, vol. i. p. 313. + + [65] _Oesterreichische medicinische Jahrbuecher_, 1875, 179. + +In view of Obersteiner's corroboration of Brown-Sequard's results +touching the artificial production and subsequent transmission of +epilepsy, Weismann accepts the facts, but, in order to save his theory +of heredity, he argues that the transmission may be due to a traumatic +introduction of "some unknown microbe" which causes the epilepsy in the +parent, and, by invading the ova or spermatozoa as the case may be, also +produces epilepsy in the offspring. Here, of course, there would be +transmission of epilepsy, but it would not be, technically speaking, an +hereditary transmission. The case would resemble that of syphilis, where +the sexual elements remain unaffected as to their congenital endowments, +although they have been made the vehicles for conveying an organic +poison to the next generation. + +Now it would seem that this suggestion is not, on the face of it, a +probable one. For "some unknown microbe" it indeed must be, which is +always on hand to enter a guinea-pig when certain operations are being +performed on certain parts of the nervous system, but yet will never +enter when operations of any kind are being effected elsewhere. +Moreover, Westphal has produced the epilepsy _without any incision_, by +striking the heads of the animals with a hammer[66]. This latter fact, +it appears to me, entirely abolishes the intrinsically improbable +suggestion touching an unknown--and strangely eclectic--microbe. +However, it is but fair to state what Weismann himself has made of this +fact. The following is what he says:-- + + [66] _Loc. cit._ + + "It is obvious that the presence of microbes can have nothing to do + with such an attack, but the shock alone must have caused + morphological and functional changes in the centre of the pons and + medulla oblongata, identical with those produced by microbes in the + other cases.... Various stimuli might cause the nervous centres + concerned to develop the convulsive attack which, together with its + after-effects, we call epilepsy. In Westphal's case, such a + stimulus would be given by a powerful mechanical shock (viz. blows + on the head with a hammer); in Brown-Sequard's experiments, by the + penetration of microbes[67]." + + [67] _Essays_, vol. i. p. 315. + +But from this passage it would seem that Weismann has failed to notice +that in "Westphal's case," as in "Brown-Sequard's experiments," the +epilepsy was _transmitted to progeny_. That epilepsy may be produced in +guinea-pigs by a method which does not involve any cutting (i.e. +possibility of inoculation) would no doubt tend to corroborate the +suggestion of microbes being concerned in its transmission when it is +produced by cutting, _if in the former case there were no such +transmission_. But as there _is_ transmission in _both_ cases, the +facts, so far as I can see, entirely abolish the suggestion. For they +prove that even when epilepsy is produced in the parents under +circumstances which render "it obvious that the presence of microbes can +have nothing to do with such an attack," the epileptiform condition is +notwithstanding transmitted to the progeny. What, then, is gained by +retaining the intrinsically improbable hypothesis of microbes to explain +the fact of transmission "in Brown-Sequard's experiments," when this +very same fact is proved to occur without the possibility of microbes +"in Westphal's case"? + +The only other objection with regard to the seeming transmission of +traumatic epilepsy which Weismann has advanced is, that such epilepsy +may be produced by two or three very different operations--viz. division +of the sciatic nerves (one or both), an injury to the spinal cord, and a +stroke on the head. Does not this show, it is asked, that the epileptic +condition of guinea-pigs is due to a generally unstable condition of the +whole nervous system and is not associated with any particular part +thereof? Well, supposing that such is the case, what would it amount to? +I cannot see that it would in any way affect the only question in +debate--viz. What is the significance of the fact that epilepsy is +_transmitted_? Even if it be but "a tendency," "a disposition," or "a +diathesis" that is transmitted, it is none the less a case of +transmission, in fact quite as much so as if the pathological state were +dependent on the impaired condition of any particular nerve-centre. For, +it must be observed, there can be no question that it is always produced +by an operation of _some_ kind. If it were ever to originate in +guinea-pigs spontaneously, there might be some room for supposing that +its transmission is due to a congenital tendency running through the +whole species--although even then it would remain unaccountable, on the +ultra-Darwinian view, why this tendency should be congenitally +_increased_ by means of an operation. But epilepsy does not originate +spontaneously in guinea-pigs; and therefore the criticism in question +appears to me irrelevant. + +Again, it may be worth while to remark that Brown-Sequard's experiments +do not disprove the possibility of its being some one nerve-centre which +is concerned in all cases of traumatic epilepsy. And this possibility +becomes, I think, a probability in view of Luciani's recent experiments +on the dog. These show that the epileptic condition can be produced in +this animal by injury to the cortical substance of the hemispheres, and +is then transmitted to progeny[68]. These experiments, therefore, are of +great interest--first, as showing that traumatic and transmissible +epilepsy is not confined to guinea-pigs; and next, as indicating that +the pathological state in question is associated with the highest +nerve-centres, which may therefore well be affected by injury to the +lower centres, or even by section of a large nerve trunk. + + [68] _Les fonctions du Cerveau_, p. 102. + +So much, then, with regard to the case of transmitted epilepsy. But now +it must be noted that, even if Weismann's suggestion touching microbes +were fully adequate to meet this case, it would still leave unaffected +those of transmitted protrusion of the eye, drooping of the eyelid, +gangrene of the ear, absence of toes, &c. In all these cases the facts, +as stated by Brown-Sequard, are plainly unamenable to any explanation +which would suppose them due to microbes, or even to any general +neurotic condition induced by the operation. They are much too definite, +peculiar, and localized. Doubtless it is on this account that the school +of Weismann has not seriously attempted to deal with them, but merely +recommends their repetition by other physiologists[69]. Certain +criticisms, however, have been urged by Weismann against the +_interpretation_ of Brown-Sequard's facts as evidence in favour of the +transmission of acquired characters. It does not appear to me that these +criticisms present much weight; but it is only fair that we should here +briefly consider them[70]. + + [69] _Essays_, vol. i. p. 82. + + [70] As Weismann gives an excellent abstract of all the alleged + facts up to date (_Essays_, vol. i. pp. 319-324), it is + needless for me to supply another, further than that which I + have already made from Brown-Sequard. + +First, with regard to Brown-Sequard's results other than the production +of transmitted epilepsy, Weismann allows that the hypothesis of microbes +can scarcely apply. In order to meet these results, therefore, he +furnishes another suggestion--viz. that where the nervous system has +sustained "a great shock," the animals are very likely to bear "weak +descendants, and such as are readily affected by disease." Then, in +answer to the obvious consideration, "that this does not explain why the +offspring should suffer from the same disease" as that which has been +produced in the parents, he adds--"But this does not appear to have been +by any means invariably the case. For 'Brown-Sequard himself says, the +changes in the eye of the offspring were of a very variable nature, and +were only occasionally exactly similar to those observed in the +parents.'" + +Now, this does not appear to me a good commentary. In the first place, +it does not apply to the other cases (such as the ears and the toes), +where the changes in the offspring, when they occurred at all, _were_ +exactly similar to those observed in the parents, save that some of them +occasionally occurred on the _opposite_ side, and frequently also on +_both_ sides of the offspring. These subordinate facts, however, will +not be regarded by any physiologist as making against the more ready +interpretation of the results as due to heredity. For a physiologist +well knows that homologous parts are apt to exhibit correlated +variability--and this especially where variations of a congenital kind +are concerned, and also where there is any reason to suppose that the +nervous system is involved. Moreover, even in the case of the eye, it +was always protrusion that was caused in the parent and transmitted to +the offspring as a result of injuring the restiform bodies of the +former; while it was always partial closure of the eyelids that was +caused and transmitted by section of the sympathetic nerve, or removal +of the cervical ganglia. Therefore, if we call such effects "diseases," +surely it _was_ "the same disease" which in each case appeared in the +parents and reappeared in their offspring. Again, the "diseases" were so +peculiar, definite, and localized, that I cannot see how they can be +reasonably ascribed to a general nervous "shock." Why, for instance, if +this were the case, should a protruding eye never result from removal +of the cervical ganglia, a drooping eyelid from a puncture of the +restiform body, a toeless foot from either or both of these operations, +and so on? In view of such considerations I cannot deem these +suggestions touching "microbes" and "diseases" as worthy of the +distinguished biologist from whom they emanate. + +Secondly, Weismann asks--How can we suppose these results to be +instances of the transmission of acquired characters, when from +Brown-Sequard's own statement of them it appears that the mutilation +itself was not inherited, but only its effects? Neither in the case of +the sciatic nerve, the sympathetic nerve, the cervical ganglion, nor the +restiform bodies, was there ever any trace of transmitted injury in the +corresponding parts of the offspring; so that, if the "diseases" from +which they suffered be regarded as hereditary, we have to suppose that a +consequence was in each case transmitted without the transmission of its +cause, which is absurd. But I do not think that this criticism can be +deemed of much weight by a physiologist as distinguished from a +naturalist. For nothing is more certain to a student of physiology, in +any of its branches, than that negative evidence, if yielded by the +microscope alone, is most precarious. Therefore it does not need a +_visible_ change in the nervous system to be present, in order that the +part affected should be functionally weak or incapable: pathology can +show numberless cases of nerve-disorder the "structural" causes of which +neither the scalpel nor the microscope can detect. So that, if any +peculiar form of nerve-disorder is transmitted to progeny, and if it be +certain that it has been caused by injury to some particular part of +the nervous system, I cannot see that there is any reason to doubt the +transmission of a nervous lesion merely on the ground that it is not +visibly discernible. Of course there may be other grounds for doubting +it; but I am satisfied that this ground is untenable. Besides, it must +be remembered, as regards the particular cases in question, that no one +has thus far investigated the histology of the matter by the greatly +improved methods which are now at our disposal. + + * * * * * + +I have now considered all the criticisms which have been advanced +against what may be called the Lamarckian interpretation of +Brown-Sequard's results; and I think it will be seen that they present +very little force--even if it can be seen that they present any force at +all. But it must be remembered that this is a different thing from +saying that the Lamarckian interpretation is the true one. The facts +alleged are, without question, highly peculiar; and, on this account +alone, Brown-Sequard's interpretation of them ought to be deemed +provisional. Hence, although as yet they have not encountered any valid +criticism from the side of ultra-Darwinian theory, I do not agree with +Darwin that, on the supposition of their truth as facts, they furnish +positive proof of the transmission of acquired characters. Rather do I +agree with Weismann that further investigation is needed in order to +establish such an important conclusion on the basis of so unusual a +class of facts. This further investigation, therefore, I have +undertaken, and will now state the results. + +Although this work was begun over twenty years ago, and then yielded +negative results, it was only within the last decade that I resumed it +more systematically, and under the tutelage of Brown-Sequard himself. +During the last two years, however, the experiments have been so much +interrupted by illness that even now the research is far from complete. +Therefore I will here confine myself to a tabular statement of the +results as far as they have hitherto gone, on the understanding that, in +so far as they are negative or doubtful, I am not yet prepared to +announce them as final. + +We may take Brown-Sequard's propositions in his own order, as already +given on page 104. + + 1st. Appearance of epilepsy in animals born of parents which had + been rendered epileptic by an injury to the spinal cord. + + 2nd. Appearance of epilepsy also in animals born of parents which + had been rendered epileptic by section of the sciatic nerve. + +I did not repeat these experiments with a view to producing epilepsy, +because, as above stated, they had been already and sufficiently +corroborated in this respect. But I repeated many times the experiments +of dividing the sciatic nerve for the purpose of testing the statements +made later on in paragraphs 7 and 8, and observed that it almost always +had the effect of producing epilepsy in the animal thus operated +upon--and this of a peculiar kind, the chief characteristics of which +may here be summarized. The epileptiform habit does not supervene until +some considerable time after the operation; it is then transitory, +lasting only for some weeks or months. While the habit endures the fits +never occur spontaneously, but only as a result of irritating a small +area of skin behind the ear on the same side of the body as that on +which the sciatic nerve had been divided. Effectual irritation may be +either mechanical (such as gentle pinching), electrical, or, though less +certainly, thermal. The area of skin in question, soon after the +epileptiform habit supervenes, and during all the time that it lasts, +swarms with lice of the kind which infest guinea-pigs--i.e. the lice +congregate in this area, on account, I think, of the animal being there +insensitive, and therefore not disturbing its parasites in that +particular spot; otherwise it would presumably throw itself into fits by +scratching that spot. On removing the skin from the area in question, no +kind or degree of irritation supplied to the subjacent tissue has any +effect in producing a fit. A fit never lasts for more than a very few +minutes, during which the animal is unconscious and convulsed, though +not with any great violence. The epileptiform habit is but rarely +transmitted to progeny. Most of these observations are in accordance +with those previously made by Brown-Sequard, and also by others who have +repeated his experiments under this heading. I can have no doubt that +the injury of the sciatic nerve or spinal cord produces a change in some +of the cerebral centres, and that it is this change--whatever it is and +in whatever part of the brain it takes place--which causes the +remarkable phenomena in question. + + 3rd. A change in the shape of the ear in animals born of parents in + which such a change was the effect of a division of the cervical + sympathetic nerve. + + 4th. Partial closure of the eyelids in animals born of parents in + which that state of the eyelids had been caused either by section + of the cervical sympathetic nerve, or the removal of the superior + cervical ganglion. + +I have not succeeded in corroborating these results. It must be added, +however, that up to the time of going to press my experiments on this, +the easiest branch of the research, have been too few fairly to prove a +negative. + + 5th. Exophthalmia in animals born of parents in which an injury to + the restiform body had produced that protrusion of the eyeball.... + In these animals, modified by heredity, the two eyes generally + protruded, although in the parents usually only one showed + exophthalmia, the lesion having been made in most cases only on one + of the corpora restiformia. + +I have fully corroborated the statement that injury to a particular spot +of the restiform body is quickly followed by a marked protrusion of the +eyeball on the same side. I have also had many cases in which some of +the progeny of parents thus affected have shown considerable protrusion +of the eyeballs on both sides, and this seemingly abnormal protrusion +has been occasionally transmitted to the next generation. Nevertheless, +I am far from satisfied that this latter fact is anything more than an +accidental coincidence. For I have never seen the so-called exophthalmia +of progeny exhibited in so high a degree as it occurs in the parents as +an immediate result of the operation, while, on examining any large +stock of normal guinea-pigs, there is found a considerable amount of +individual variation in regard to prominence of eyeballs. Therefore, +while not denying that the obviously abnormal amount of protrusion due +to the operation may be inherited in lesser degrees, and thus may be the +cause of the unusual degree of prominence which is sometimes seen in the +eyeballs of progeny born of exophthalmic parents, I am unable to affirm +so important a conclusion on the basis supplied by these experiments. + + 6th. Haematoma and dry gangrene of the ears in animals born of + parents in which these ear-alterations had been caused by an injury + to the restiform body. + +As regards the animals operated upon (i. e. the parents), I find that +the haematoma and dry gangrene may supervene either several weeks after +the operation, or at any subsequent time up to many months. When it does +supervene it usually affects the upper parts of both ears, and may then +eat its way down until, in extreme cases, it has entirely consumed +two-thirds of the tissue of both ears. As regards the progeny of animals +thus affected, in some cases, but by no means in all, a similarly morbid +state of the ears may arise apparently at any time in the life-history +of the individual. But I have observed that in cases where two or more +individuals _of the same litter_ develop this diseased condition, they +usually do so at about the same time--even though this be many months +after birth, and therefore after the animals are fully grown. But in +progeny the morbid process never goes so far as in the parents which +have been operated upon, and it almost always affects the _middle_ +thirds of the ears. In order to illustrate these points, reproductions +of two of my photographs are appended. They represent the consequences +of the operation on a male and a female guinea-pig. Among the progeny of +both these animals there were several in which a portion of each ear was +consumed by apparently the same process, where, of course, there had +been no operation. + +[Illustration: FIG. 1.--Reproduction of photographs from life of a male +and female guinea-pig, whose left restiform bodies had been injured by a +scalpel six months previously. The loss of tissue in both ears was due +to haematoma and dry gangrene, which, however, had ceased when the +photograph was taken.] + +It should be observed that not only is a different _part_ of the ear +affected in the progeny, but also a very much less _quantity_ thereof. +Naturally, therefore, the hypothesis of heredity seems less probable +than that of mere coincidence on the one hand, or of transmitted +microbes on the other. But I hope to have fairly excluded both these +alternative explanations. For, as regards merely accidental coincidence, +I have never seen this very peculiar morbid process in the ears, or in +any other parts, of guinea-pigs which have neither themselves had their +restiform bodies injured, nor been born of parents thus mutilated. As +regards the hypothesis of microbes, I have tried to inoculate the +corresponding parts of the ears of normal guinea-pigs, by first +scarifying those parts and then rubbing them with the diseased surfaces +of the ears of mutilated guinea-pigs; but have not been able in this way +to communicate the disease. + +It will be seen that the above results in large measure corroborate the +statements of Brown-Sequard; and it is only fair to add that he told me +they are the results which he had himself obtained most frequently, but +that he had also met with many cases where the diseased condition of the +ears in parents affected the same parts in their progeny, and also +occurred in more equal degrees. Lastly, I should like to remark, with +regard to these experiments on restiform bodies, and for the benefit of +any one else who may hereafter repeat them, that it will be necessary +for him to obtain precise information touching the _modus operandi_. For +it is only one very localized spot in each restiform body which has to +be injured in order to produce any of the results in question. I myself +lost two years of work on account of not knowing this exact spot before +going to Paris for the purpose of seeing Brown-Sequard himself perform +the operation. I had in the preceding year seen one of his assistants do +so, but this gentleman had a much more careless method, and one which in +my hands yielded uniformly negative results. The exact spot in question +in the restiform body is as far forwards as it is possible to reach, and +as far down in depth as is compatible with not producing rotatory +movements. + + 7th. Absence of two toes out of the three of the hind leg, and + sometimes of the three, in animals whose parents had eaten up their + hind-leg toes which had become anaesthetic from a section of the + sciatic nerve alone, or of that nerve and also of the crural. + Sometimes, instead of complete absence of the toes, only a part of + one or two or three was missing in the young, although in the + parent not only the toes but the whole foot were absent. + +As I found that the results here described were usually given by +division of the sciatic nerve alone--or, more correctly, by excision of +a considerable portion of the nerve, in order to prevent regeneration--I +did not also divide the crural. But, although I have bred numerous +litters from parents thus injured, there has been no case of any +inherited deficiency of toes. My experiments in this connexion were +carried on through a series of six successive generations, so as to +produce, if possible, a cumulative effect. Nevertheless, no effect of +any kind was produced. On the other hand, Brown-Sequard informed me that +he had observed this inherited absence of toes only in about one or two +per cent. of cases. Hence it is possible enough, that my experiments +have not been sufficiently numerous to furnish a case. It may be added +that there is here no measurable possibility of accidental coincidence +(seeing that normal guinea-pigs do not seem ever to produce young with +any deficiency of toes), while the only possibility of mal-observation +consists in some error with regard to the isolation (or the tabulation) +of parents and progeny. Such an error, however, may easily arise. For +gangrene of the toes does not set in till some considerable time after +division of the sciatic nerve. Hence, if the wound be healed before the +gangrene begins, and if any mistake has been made with regard to the +isolation (or tabulation) of the animal, it becomes possible that the +latter should be recorded as an uninjured, instead of an injured, +individual. On this account one would like to be assured that +Brown-Sequard took the precaution of examining the state of the sciatic +nerve in those comparatively few specimens which he alleges to have +displayed such exceedingly definite proof of the inheritance of a +mutilation. For it is needless to remark, after what has been said in +the preceding chapter on the analogous case of epilepsy, that the proof +would not be regarded by any physiologist as displaced by the fact that +there is no observable deficiency in the sciatic nerve of the toeless +young. + + 8th. Appearance of various morbid states of the skin and hair of + the neck and face in animals born of parents having had similar + alterations in the same parts, as effects of an injury to the + sciatic nerve. + +I have not paid any attention to this paragraph, because the facts which +it alleges did not seem of a sufficiently definite character to serve as +a guide to further experiment. + +On the whole, then, as regards Brown-Sequard's experiments, it will be +seen that I have not been able to furnish any approach to a full +corroboration. But I must repeat that my own experiments have not as yet +been sufficiently numerous to justify me in repudiating those of his +statements which I have not been able to verify. + +The only other experimental results, where animals are concerned, which +seemed to tell on the side of Lamarckianism, are those of Mr. +Cunningham, already alluded to. But, as the research is still in +progress, the school of Weismann may fairly say that it would be +premature to discuss its theoretical bearings. + + * * * * * + +Passing now from experiments on animals to experiments on plants, I must +again ask it to be borne in mind, that here also no researches have been +published, which have had for their object the testing of the question +on which we are engaged. As in the case of animals, therefore, so in +that of plants, we are dependent for any experimental results bearing +upon the subject to such as have been gained incidentally during the +course of investigations in quite other directions. + +Allusion has already been made, in my previous essay, to De Vries' +observations on the chromatophores of algae passing from the ovum of the +mother to the daughter organism; and we have seen that even Weismann +admits, "It appears possible that a transmission of somatogenetic +variation has here occurred[71]." It will now be my object to show that +such variations appear to be sometimes transmitted in the case of +higher plants, and this under circumstances which carry much less +equivocal evidence of the inheritance of acquired characters, than can +be rendered by the much more simple organization of an alga. + + [71] _Examination of Weismannism_, p. 83. + +I have previously mentioned Hoffmann's experiments on transplantation, +the result of which was to show that variations, directly induced by +changed conditions of life, were reproduced by seed[72]. Weismann, +however, as we have seen, questions the _somatogenetic_ origin of these +variations--attributing the facts to a _blastogenetic_ change produced +in the plants by a direct action of the changed conditions upon the +germ-plasm itself[73]. And he points out that whether he is right or +wrong in this interpretation can only be settled by ascertaining whether +the observable somatic changes occur in the generation which is first +exposed to the changed conditions of life. If they do occur in the first +generation, they are somatogenetic changes, which afterwards react on +the substance of heredity, so as to transmit the acquired peculiarities +to progeny. But if they do not occur till the second (or any later) +generation, they are presumably blastogenetic. Unfortunately Hoffmann +does not appear to have attended to this point with sufficient care, but +there are other experiments of the same kind where the point has been +specially observed. + + [72] _Examination of Wiesmannism_, p. 93. + + [73] _Ibid._ p. 153. + +For instance, M. L. A. Carriere[74] gathered seed from the wild radish +(_Raphanus Raphanistrum_) in France, and sowed one lot in the light dry +soil near the Museum of Natural History in Paris, while another lot was +sown by him at the same time in heavy soil elsewhere. His object was to +ascertain whether he could produce a good cultivated radish by +methodical selection; and this he did; in a wonderfully rapid manner, +during the course of a very few generations. But the point for us is, +that _from the first_ the plants grown in the light soil of Paris +presented sundry marked differences from those grown in the heavy soil +of the country; and that these points of difference had nothing to do +with the variations on which his artificial selection was brought to +bear. For while his artificial selection was directed to increasing the +_size_ of the "root," the differences in question had reference to its +_form_ and _colour_. In Paris an elongated form prevailed, which +presented either a white or a rose colour: in the country the form was +more rounded, and the colour violet, dark brown, or "almost black." Now, +as these differences were strongly apparent in the first generation, and +were not afterwards made the subject of selection, both in origin and +development they must have been due to "climatic" influences acting on +the somatic tissues. And although the author does not appear to have +tested their hereditary characters by afterwards sowing the seed from +the Paris variety in the country, or _vice versa_, we may fairly +conclude that these changes must have been hereditary--1st, from the +fact of their intensification in the course of the five sequent +generations over which the experiment extended, and, 2nd, from the very +analogous results which were similarly obtained in the following case +with another genus, where both the somatogenetic and the hereditary +characters of the change were carefully and specially observed. This +case is as follows. + + [74] _Origine des Plantes Domestiques, demontree par la culture du + Radis Sauvage_ (Paris, 1869). + +The late Professor James Buckman, F.R.S., saved some seed from wild +parsnips (_P. sativa_) in the summer of 1847, and sowed under changed +conditions of life in the spring of 1848. The plants grown from these +wild seeds were for the most part like wild plants; but some of them had +"already (i.e. in the autumn of 1848) the light green and smooth aspect +devoid of hairs which is peculiar to the cultivated plant; and among the +latter there were a few with longer leaves and broader divisions of +leaf-lobes than the rest--the leaves, too, all growing systematically +round one central bud. The roots of the plant when taken up were +observed to be for the most part more fleshy than those of wild +examples[75]." + + [75] _Journl. Agric. Soc._ 1848. + +Professor Buckman then proceeds to describe how he selected the best +samples for cultivation in succeeding generations, till eventually the +variety which he called "The Student" was produced, and which Messrs. +Sutton still regard as the best variety in their catalogue. That is to +say, it has come true to seed for the last forty years; and although +such great excellence and stability are doubtless in chief part due to +the subsequent process of selection by Professor Buckman in the years +1848-1850, this does not affect the point with which we are here +concerned--namely, that the somatogenetic changes of the plants in the +first generation were transmitted by seed to the second generation, and +thus furnished Professor Buckman with the material for his subsequent +process of selection. And the changes in question were not merely of a +very definite character, but also of what may be termed a very _local_ +character--affecting only particular tissues of the soma, and therefore +expressive of a high degree of _representation_ on the part of the +subsequently developed seed, by which they were faithfully reproduced in +the next generation. + +Here is another case. M. Lesage examined the tissues of a large number +of plants growing both near to, and remote from, the sea. He suspected +that the characteristic fleshiness, &c. of seaside plants was due to the +influence of sea-salt; and proved that such was the case by causing the +characters to occur in inland plants as a result of watering them with +salt-water. Then he adds:-- + + "J'ai reussi surtout pour le _Lepidium sativum_ cultive en 1888; + j'ai obtenu pour la meme plante des resultats plus nets encore dans + la culture de 1889, entreprise en semant les graines recoltees avec + soin des pots de l'annee precedente et traitees exactement de la + meme facon[76]." + + [76] _Rev. Gen. de Bot._ tom. ii. p. 64. + +Here, it will be observed, there was no selection; and therefore the +increased hereditary effect in the second generation must apparently be +ascribed to a continuance of influence exercised by somatic tissues on +germinal elements; for at the time when the changes were produced no +seed had been formed. In other words, the accumulated change, like the +initial change, would seem to have been exclusively of somatogenetic +origin; and yet it so influenced the qualities of the seed (as this was +afterwards formed), that the augmented changes were transmitted to the +next generation, part for part, as the lesser changes had occurred in +the preceding generation. "This experiment, therefore, like Professor +Buckman's, shows that the alteration of the tissues was carried on in +the second generation from the point gained in the first. In both cases +no germ-plasm (in the germ-cells) existed at the time during which the +alterations arose, as they were confined to the vegetative system; and +in the case of the parsnips and carrots, being biennials no germ-cells +are produced till the second year has arrived[77]." + + [77] I am indebted to the Rev. G. Henslow for the references to + these cases. This and the passages which follow are quoted from + his letters to me. + +Once more, Professor Bailey remarks:-- + + "Squashes often show remarkable differences when grown upon + different soils; and these differences can sometimes be perpetuated + for a time by seeds. The writer has produced, from the same parent, + squashes so dissimilar, through the simple agency of a change of + soil in one season, that they might readily be taken for distinct + varieties. Peas are known to vary in the same manner. The seeds of + a row of peas of the same kind, last year gave the writer marked + variations due to differences of soil.... Pea-growers characterize + soils as 'good' and 'viney.' Upon the latter sort the plants run to + vine at the expense of the fruit, and their offspring for two or + three generations have the same tendency[78]." + + [78] _Gardener's Chronicle_, May 31, 1890, p. 677. + +I think these several cases are enough to show that, while the +Weismannian assumption as to the seeming transmission of somatogenetic +characters being restricted to the lowest kinds of plants is purely +gratuitous, there is no small amount of evidence to the contrary--or +evidence which seems to prove that a similar transmission occurs +likewise in the higher plants. And no doubt many additional cases might +be advanced by any one who is well read in the literature of economic +botany. + +It appears to me that the only answer to such cases would be furnished +by supposing that the hereditary changes are due to an alteration of the +residual "germ-plasm" in the wild seed, when this is first exposed to +the changed conditions of life, due to its growth in a strange kind of +soil--e.g. while germinating in an unusual kind of earth for producing +the first generation. But this would be going a long way to save an +hypothesis. In case, however, it should now be suggested, I may remark +that it would be negatived by the following facts.[79] + + [79] Since the above was written Professor Weismann has advanced, in + _The Germ-plasm_, a suggestion very similar to this. It is + sufficient here to remark, that nearly all the facts and + considerations which ensue in the present chapter are + applicable to his suggestion, the essence of which is + anticipated in the above paragraph. + +In the first place, an endless number of cases might be quoted where +somatogenetic changes thus produced by changed conditions of life are +not hereditary. Therefore, in all these cases it is certainly not the +"germ-plasm" that is affected. In other words, there can be no question +that somatogenetic changes of the kinds above mentioned do very readily +admit of being produced in the first generation by changes of soil, +altitude, &c. And that somatogenetic changes thus produced should not +always--or even generally--prove themselves to be hereditary from the +first moment of their occurrence, is no more than any theory of +heredity would expect. Indeed, looking to the known potency of +reversion, the wonder is that in any case such changes should become +hereditary in a single generation. On the other hand, there is no reason +to imagine that the hypothetical germ-plasm--howsoever _unstable_ we may +suppose it to be--can admit of being directly affected by a change of +soil in a single generation. For, on this view, it must presumably be +chiefly affected during the short time that the seed is germinating; and +during that time the changed conditions can scarcely be conceived as +having any points of attack, so to speak, upon the residual germ-plasm. +There are no roots on which the change of _soil_ can make itself +perceptible, nor any stem and leaves on which the change of _atmosphere_ +can operate. Yet the changed condition's may produce hereditary +modifications in any parts of the plant, which are not only precisely +analogous to non-hereditary changes similarly produced in the somatic +tissues of innumerable other plants, but are always of precisely the +same kind in the same lot of plants that are affected. When all the +radishes grown from wild seed in Paris, for instance, varied in the +direction of rotundity and dark colour, while those grown in the country +presented the opposite characters, we can well understand the facts as +due to an entire season's action upon the whole of the growing plant, +with the result that all the changes produced in each set of plants were +similar--just as in the cases where similarly "climatic" modifications +are not hereditary, and therefore unquestionably due to changed +conditions acting on roots, stems, leaves, or flowers, as the case may +be. On the other hand, it is not thus intelligible that during the +short time of germination the changed conditions should effect a +re-shuffling (or any other modification) of the "germ-plasm" in the +seeds--and this in such a manner that the effect on the residual +germ-plasm reserved for future generations is precisely similar to that +produced on the somatic tissues of the developing embryo. + +In the second place, as we have seen, in some of the foregoing cases the +changes were produced months--and even years--before the seeds of the +first germination were formed. Therefore the hereditary effect, if +subsequent to the period of embryonic germination, must have been +produced on germ-plasm as this occurs diffused through the somatic +tissues. But, if so, we shall have to suppose that such germ-plasm is +afterwards gathered in the seeds when these are subsequently formed. +This supposition, however, would be radically opposed to Weismann's +theory of heredity: nor do I know of any other theory with which it +would be reconcilable, save such as entertain the possibility of the +Lamarckian factors. + +Lastly, in the third place, I deem the following considerations of the +highest importance:-- + + "As other instances in which peculiar structures are now hereditary + may be mentioned aquatic plants and those producing subterraneous + stems. Whether they be dicotyledons or monocotyledons, there is a + fundamental agreement in the anatomy of the roots and stem of + aquatic plants, and, in many cases, of the leaves as well. Such has + hitherto been attributed to the aquatic habit. The inference or + deduction was, of course, based upon innumerable coincidences; the + water being supposed to be the direct cause of the degenerate + structures, which are hereditary and characteristic of such plants + in the wild state. M. Costantin has, however, verified this + deduction, by making terrestrial and aerial stems to grow + underground and in water: the structures _at once_ began to assume + the subterranean or aquatic type, as the case might be; and, + conversely, aquatic plants made to grow upon land _at once_ began + to assume the terrestrial type of structure, while analogous + results followed changes from a subterranean to an aerial position, + and _vice versa_." + +This is also quoted from the Rev. Prof. Henslow's letters to me, and the +important point in it is, that the great changes in question are proved +to be of a purely "somatogenetic" kind; for they occurred "at once" _in +the ready-grown plant_, when the organs concerned were exposed to the +change from aquatic to terrestrial life, or _vice versa_--and also from +a subterranean to an aerial position, or _vice versa_. Consequently, +even the abstract possibility of the changed conditions of life having +operated on the _seed_ is here excluded. Yet the changes are of +precisely the same kind as are now _hereditary_ in the wild species. It +thus appears undeniable that all these remarkable and uniform changes +must originally have been somatogenetic changes; yet they have now +become blastogenetic. This much, I say, seems undeniable; and therefore +it goes a long way to prove that the non-blastogenetic character of the +changes has been due to their originally somatogenetic character. For, +if not, how did natural selection ever get an opportunity of making any +of them blastogenetic, when every individual plant has always presented +them as already given somatogenetically? This last consideration appears +in no small measure to justify the opinion of Mr. Henslow, who +concludes--"These experiments prove, not only that the influence of the +environment is _at once_ felt by the organ; but that it is indubitably +the _cause_ of the now specific and hereditary traits peculiar to +normally aquatic, subterranean, and aerial stems, or roots[80]." + + [80] It also serves to show that Weismann's newer doctrine of + similar "determinants" occurring both in the germ and in the + somatic tissues is a doctrine which cannot be applied to rebut + this evidence of the transmission of acquired characters in + plants. Therefore even its hypothetical validity as applied by + him to explain the seasonal variation of butterflies is + rendered in a high degree dubious. + +He continues to furnish other instances in the same line of proof--such +as the distinctive "habits" of insectivorous, parasitic, and climbing +plants; the difference in structure between the upper and under sides of +horizontal leaves, &c. "For here, as in all organs, we discover by +experiment how easily the anatomy of plants can be affected by their +environment; and that, as long as the latter is constant, so are the +characters of the plants constant and hereditary." + + [The following letter, contributed by Dr. Hill to _Nature_, vol. I. + p. 617, may here be quoted. C. Ll. M. + + "It may be of interest to your readers to know that two guinea-pigs + were born at Oxford a day or two before the death Dr. Romanes, both + of which exhibited a well-marked droop of the left upper eyelid. + These guinea-pigs were the offspring of a male and a female + guinea-pig in both of which I had produced for Dr. Romanes, some + months earlier, a droop of the left upper eyelid by division of the + left cervical sympathetic nerve. This result is a corroboration of + the series of Brown-Sequard's experiments on the inheritance of + acquired characteristics. A very large series of such experiments + are of course needed to eliminate all sources of error, but this I + unfortunately cannot carry out at present, owing to the need of a + special farm in the country, for the proper care and breeding of + the animals.--LEONARD HILL. + + "Physiological Laboratory, Univ. Coll. London, Oct. 18, 1894."] + + + + +CHAPTER V. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_continued_). + + +(A. and B.) + + +_Direct and Indirect Evidence in favour of the Non-inheritance of +Acquired Characters_[81]. + + [81] [_See_ note appended to Preface. C. LI. M.] + +The strongest argument in favour of "continuity" is that based upon the +immense difference between congenital and acquired characters in respect +of heritability. For that there is a great difference in this respect is +a matter of undeniable fact. And it is obvious that this difference, the +importance of which must be allowed its full weight, is just what we +should expect on the theory of the continuity of the germ-plasm, as +opposed to that of pangenesis. Indeed it may be said that the difference +in question, while it constitutes important _evidence_ in favour of the +former theory, is a _difficulty_ in the way of the latter. But here two +or three considerations must be borne in mind. + +In the first place, this fact has long been one which has met with wide +recognition and now constitutes the main ground on which the theory of +continuity stands. That is to say, it was the previous knowledge of +this contrast between congenital and acquired characters which led to +the formulation of a theory of continuity by Mr. Galton, and to its +subsequent development by Prof Weismann. + +But, in the second place, there is a wide difference between the +certainty of this fact and that of the theory based upon it. The certain +fact is, that a great distinction in respect of heritability is +observable between congenital and acquired characters. The theory, as +formulated by Weismann, is that the distinction is not only great but +absolute, or, in other words, that in no case and in no degree can any +acquired character be ever inherited. This hypothesis, it will be +observed, goes far beyond the observed fact, for it is obviously +possible that, notwithstanding this great difference in regard to +heritability between congenital and acquired characters, the latter may +nevertheless, sometimes and in some degree, be inherited, however much +difficulty we may experience in observing these lesser phenomena in +presence of the greater. The Weismannian hypothesis of _absolute_ +continuity is one thing, while the observed fact of at least a _high +relative degree_ of continuity is quite another thing. And it is +necessary to be emphatic on this point, since some of the reviewers of +my _Examination of Weismannism_ confound these two things. Being +apparently under the impression that it was reserved for Weismann to +perceive the fact of there being a great difference between the +heritability of congenital and acquired characters, they deem it +inconsistent in me to acknowledge this fact while at the same time +questioning the hypothetical basis of his fundamental postulate touching +the absolute continuity of germ-plasm. It is one merit of Galton's +theory, as against Weismann's, that it does not dogmatically exclude the +possible interruption of continuity on some occasions and in some +degree. Herein, indeed, would seem to lie the central core of the whole +question in dispute. For it is certain and has long been known that +individually acquired characters are at all events much less heritable +than are long-inherited or congenital ones. But Lamarckian theory +supposes that congenital characters were in some cases originally +acquired, and that what are now blastogenetic characters were in some +cases at first somatogenetic and have become blastogenetic only in +virtue of sufficiently long inheritance. Since Darwin's time, however, +evolutionists (even of the so-called Lamarckian type) have supposed that +natural selection greatly assists this process of determining which +somatogenetic characters shall become congenital or blastogenetic. Hence +all schools of evolutionists are, and have long been, agreed in +regarding the continuity principle as true in the main. No evolutionist +would at any time have propounded the view that one generation depends +for _all_ its characters on those acquired by its _immediate_ ancestors, +for this would merely be to unsay the theory of Evolution itself, as +well as to deny the patent facts of heredity as shown, for example, in +atavism. At most only some fraction of a _per cent._ could be supposed +to do so. But Weismann's contention is that this principle is not only +true in the main, but _absolutely_ true; so that natural selection +becomes all in all or not at all. Unless Weismannism be regarded as +this doctrine of absolutism it permits no basis for his attempted theory +of evolution. + +And, whatever may be said to the contrary by the more enthusiastic +followers of Prof. Weismann, I must insist that there is the widest +possible difference between the truly scientific question of fact which +is assumed by Weismann as answered (the base-line of the diagram on p. +43), and the elaborate structure of deductive reasoning which he has +reared on this assumption (the Y-like structure). Even if the assumption +should ever admit of inductive proof, the almost bewildering edifice of +deductive reasoning which he has built upon it would still appear to me +to present extremely little value of a scientific kind. Interesting +though it may be as a monument of ingenious speculation hitherto unique +in the history of science, the mere flimsiness of its material must +always prevent its far-reaching conclusions from being worthy of serious +attention from a biological point of view. But having already attempted +to show fully in my _Examination_ this great distinction between the +scientific importance of the question which lies at the base of +"Weismannism," and that of the system which he has constructed on his +assumed answer thereto, I need not now say anything further with regard +to it. + +Again, on the present occasion and in this connexion I should like to +dissipate a misunderstanding into which some of the reviewers of the +work just mentioned have fallen. They appear to have concluded that +because I have criticized unfavourably a considerable number of +Weismann's theories, I have shown myself hostile to his entire system. +Such, however, is by no means the case; and the misunderstanding can +only be accounted for by supposing that the strongly partisan spirit +which these critics display on the side of neo-Darwinism has rendered +them incapable of appreciating any attempt at impartial--or even so much +as independent--criticism. At all events, it is a matter of fact that +throughout the work in question I have been particularly careful to +avoid this misunderstanding as to my own position. Over and over again +it is there stated that, far from having any objection to the principle +of "Continuity" as represented in the base-line of the above diagram, I +have been convinced of its truth ever since reading Mr. Galton's _Theory +of Heredity_ in 1875. All the "hard words" which I have written against +Weismann's system of theories have reference to those parts of it which +go to constitute the Y-like structure of the diagram. + +It is, however, desirable to recur to another point, and one which I +hope will be borne in mind throughout the following discussion. It has +already been stated, a few pages back, that the doctrine of continuity +admits of being held in two very different significations. It may be +held as absolute, or as relative. In the former case we have the +Weismannian doctrine of germ-plasm: the substance of heredity is taken +to be a substance _per se_, which has always occupied a separate +"sphere" of its own, without any contact with that of somatoplasm +further than is required for its lodgement and nutrition; hence it can +never have been in any degree modified as to its hereditary qualities by +use-inheritance or any other kind of somatogenetic change; it has been +_absolutely_ continuous "since the first origin of life." On the other +hand, the doctrine of continuity may be held in the widely different +sense in which it has been presented by Galton's theory of Stirp. Here +the doctrine is, that while for the most part the phenomena of heredity +are due to the continuity of the substance of heredity through +numberless generations, this substance ("Stirp") is nevertheless not +absolutely continuous, but may admit, in small though cumulative +degrees, of modification by use-inheritance and other factors of the +Lamarckian kind. Now this all-important distinction between these two +theories of continuity has been fully explained and thoroughly discussed +in my _Examination_; therefore I will not here repeat myself further +than to make the following remarks. + +The Weismannian doctrine of continuity as absolute (base-line of the +diagram) is necessary for the vast edifice of theories which he has +raised upon it (the Y), first as to the minute nature and exact +composition of the substance of heredity itself ("Germ-plasm"), next as +to the precise mechanism of its action in producing the visible +phenomena of heredity, variation, and all allied phenomena, and, lastly, +the elaborate and ever-changing theory of organic evolution which is +either founded on or interwoven with this vast system of hypothetic +speculation. Galton's doctrine of continuity, on the other hand, is a +"Theory of Heredity," and a theory of heredity alone. It does not meddle +with any other matters whatsoever, and rigidly avoids all speculation +further than is necessary for the bare statement and inductive support +of the doctrine in question. Hence, it would appear that this, the only +important respect wherein the doctrine of continuity as held by Galton +differs from the doctrine as held by Weismann, arisen from the necessity +under which the latter finds himself of postulating _absolute_ +continuity as a logical basis for his deductive theory of the precise +mechanism of heredity on the one hand, and of his similarly deductive +theory of evolution on the other. So far as the doctrine of continuity +is itself concerned (i.e. the question of the inheritance of acquired +characters), there is certainly no more inductive reason for supposing +the continuity absolute "since the first origin of life," than there is +for supposing it to be more or less susceptible of interruption by the +Lamarckian factors. In other words, but for the sake of constructing a +speculative foundation for the support of his further theories as to +"the architecture of germ-plasm" and the factors of organic evolution, +there is no reason why Weismann should maintain the absolute separation +of the "sphere" of germ-plasm from that of somatoplasm. On the contrary, +he has no reason for concluding against even a considerable and a +frequent amount of cutting, or overlapping, on the part of these two +spheres. + +But although this seems to me sufficiently obvious, as I have shown at +greater length in the _Examination of Weismannism_, it must not be +understood that I hold that there is room for any large amount of such +overlapping. On the contrary, it appears to me as certain as anything +can well be that the amount of such overlapping from one generation to +another, if it ever occur at all, must be exceedingly small, so that, +if we have regard to only a few sequent generations, the effects of +use-inheritance, and Lamarckian factors are, at all events as a rule, +demonstrably imperceptible. But this fact does not constitute any +evidence--as Weismann and his followers seem to suppose--against a +possibly important influence being exercised by the Lamarckian factors, +in the way of gradual increments through a long series of generations. +It has long been well known that acquired characters are at best far +less fully and far less certainly inherited than are congenital ones. +And this fact is of itself sufficient to prove the doctrine of +continuity to the extent that even the Lamarckian is rationally bound to +concede. But the fact yields no proof--scarcely indeed so much as a +presumption--in favour of the doctrine of continuity as absolute. For it +is sufficiently obvious that the adaptive work of heredity could not be +carried on at all if there had to be a discontinuity in the substance of +heredity at every generation, or even after any very large number of +generations. + +Little more need be said concerning the arguments which fall under the +headings A and B. The Indirect evidence is considered in Appendix I of +the _Examination of Weismannism_; while the Direct evidence is +considered in the text of that work in treating of Professor Weismann's +researches on the _Hydromedusae_ (pp. 71-76). + +The facts of karyokinesis are generally claimed by the school of +Weismann as making exclusively in favour of continuity as absolute. But +this is a partisan view to take. In any impartial survey it should be +seen that while the facts are fairly interpretable on Weismann's theory, +they are by no means proof thereof. For any other theory of Heredity +must suppose the material of heredity to be of a kind more or less +specialized, and the mechanism of heredity extremely precise and well +ordered. And this is all that the facts of karyokinesis prove. Granting +that they prove continuity, they cannot be held to prove that continuity +to be absolute. In other words, the facts are by no means incompatible +with even a large amount of commerce between germ-plasm and +somato-plasm, or a frequent transmission of acquired characters. + +Again, Weismann's theory, that the somatic and the germ-plasm +determinants may be similarly and simultaneously modified by external +conditions may be extended much further than he has used it himself, so +as to exclude, or at any rate invalidate, _all_ evidence in favour of +Lamarckianism, other than the inheritance of the effects of use and +disuse. All evidence from apparently inherited effects produced by +change of external conditions is thus virtually put out of court, +leaving only evidence from the apparently inherited effects of +functionally produced modifications. And this line of evidence is +invalidated by Panmixia. Hence there remain only the arguments from +selective value and co-adaptation. Weismann meets these by adducing the +case of neuter insects, which have been already considered at sufficient +length. + + +(C.) +_Experimental Evidence as to the Non-inheritance of Acquired +Characters._ + + +Let us now proceed to the experimental evidence which has been adduced +on the side of Weismannism. + +Taking this evidence in order of date, we have first to mention that on +which the school of Weismann has hitherto been satisfied almost +exclusively to rely. This is the line of negative evidence, or the +seeming absence of any experimental demonstration of the inheritance of +acquired characters. This kind of evidence, however, presents much less +cogency than is usually supposed. And it has been shown in the last +chapter that the amount of experimental evidence in favour of the +transmission of acquired characters is more considerable than the school +of Weismann seems to be aware--especially in the vegetable kingdom. I do +not think that this negative line of evidence presents much weight; and, +to show that I am not biassed in forming this judgement, I may here +state that few have more reason than myself for appreciating the weight +of such evidence. For, as already stated, when first led to doubt the +Lamarckian factors, now more than twenty years ago, I undertook a +research upon the whole question--only a part of which was devoted to +testing the particular case of Brown-Sequard's statements, with the +result recorded in the preceding chapter. As this research yielded +negative results in all its divisions--and, not only in the matter of +Brown-Sequard's statements--I have not hitherto published a word upon +the subject. But it now seems worth while to do so, and for the +following reasons. + +First, as just observed, a brief account of my old experiences in this +field will serve to show what good reason I have for feeling the weight +of such negative evidence in favour of Continuity as arises from failure +to produce any good experimental evidence to the contrary. In the second +place, now that the question has become one of world-wide interest, it +would seem that even negative results deserve to be published for +whatever they may be worth on the side of Neo-Darwinism. Lastly, in the +third place, although the research yielded negative results in my hands, +it is perhaps not undesirable to state the nature of it, if only to +furnish suggestions to other physiologists, in whose hands the +experiments--especially in these days of antiseptics--may lead to a +different termination. Altogether I made thousands of experiments in +graft-hydridization (comprising bines, bulbs of various kinds, buds, and +tubers); but with uniformly negative results. With animals I tried a +number of experiments in grafting characteristic congenital tissues from +one variety on another--such as the combs of Spanish cocks upon the +heads of Hamburgs; also, in mice and rats, the grafting together of +different varieties; and, in rabbits and bitches, the transplantation of +ovaries of newly-born individuals belonging to different well-marked +breeds. This latter experiment seems to be one which, if successfully +performed (so that the transplanted ovaries would form their attachment +in a young bitch puppy and subsequently yield progeny to a dog of the +same breed as herself) would furnish a crucial test as to the +inheritance or non-inheritance of acquired characters. Therefore I +devoted to it a large share of my attention, and tried the experiment in +several different ways. But I was never able to get the foreign +ovary--or even any portion thereof--to graft. Eventually the passing of +the Vivisection Act caused me to abandon the whole research as far as +animals were concerned--a research, indeed, of which I had become +heartily tired, since in no one instance did I obtain any adhesion. +During the last few years, however, I have returned to these experiments +under a licence, and with antiseptic precautions, but with a similar +want of success. Perhaps this prolonged and uniformly fruitless +experience may now have the effect of saving the time of other +physiologists, by warning them off the roads where there seems to be no +thoroughfare. On the other hand, it may possibly lead some one else to +try some variation in the method, or in the material, which has not +occurred to me. In particular, I am not without hope that the +transplantation of ovaries in very young animals may eventually prove to +be physiologically possible; and, if so, that the whole issue as between +the rival theories of heredity will be settled by the result of a single +experiment. Possibly some of the invertebrata will be found to furnish +the suitable material, although I have been unable to think of any of +these which present sufficiently well-marked varieties for the purpose. +But, pending the successful accomplishment of this particular experiment +in the grafting of any animal tissue, I think it would be clearly +unjustifiable to conclude against the Lamarckian factors on the ground +of any other experiments yielding negative results in but one generation +or even in a large number of sequent generations. + +For instance, the latter consideration applies to the negative results +of Mr. Francis Galton's celebrated _Experiments in Pangenesis_.[82]. +These consisted in transfusing the blood of one variety of rabbit into +the veins of both sexes of another, and then allowing the latter to +breed together: in no case was there any appearance in the progeny of +characters distinctive of the variety from which the transfused blood +was derived. But, as Mr. Galton himself subsequently allowed, this +negative result constitutes no disproof of pangenesis, seeing that only +a portion of the parents' blood was replaced; that this portion, even if +charged with "gemmules," would contain but a very small number of these +hypothetical bodies, compared with those contained in all the tissues of +the parents; and that even this small proportional number would +presumably be soon overwhelmed by those contained in blood newly-made by +the parents. Nevertheless the experiment was unquestionably worth +trying, on the chance of its yielding a positive result; for, in this +event, the question at issue would have been closed. Accordingly I +repeated these experiments (with the kind help of Professor Schaefer), +but with slight differences in the method, designed to give pangenesis a +better chance, so to speak. + + [82] _Proc. R. S. 1871._ + +Thus I chose wild rabbits to supply the blood, and Himalayan to receive +it--the former being the ancestral type (and therefore giving reversion +an opportunity of coming into play), while the latter, although a +product of domestication, is a remarkably constant variety, and one +which differs very much in size and colour from the parent species. +Again, instead of a single transfusion, there were several transfusions +performed at different times. Moreover, we did not merely allow the +blood of one rabbit to flow into the veins of the other (whereby little +more than half the blood could be substituted); but sacrificed three +wild rabbits for refilling the vascular system of each tame one on each +occasion. Even as thus improved, however, the experiment yielded only +negative results, which, therefore, we never published. + +Subsequently I found that all this labour, both on Mr. Galton's part and +our own, was simply thrown away--not because it yielded only negative +results, but because it did not serve as a crucial experiment at all. +The material chosen was unserviceable for the purpose, inasmuch as +rabbits, even when crossed in the ordinary way, never throw intermediate +characters. Needless to say, had I been aware of this fact before, I +should never have repeated Mr. Galton's experiments--nor, indeed, would +he have originally performed them had he been aware of it. So all this +work goes for nothing. The research must begin all over again with some +other animals, the varieties of which when crossed do throw intermediate +characters. + +Therefore I have this year made arrangements for again repeating the +experiments in question--only, instead of rabbits, using well-marked +varieties of dogs. A renewed attack of illness, however, has +necessitated the surrender of this research to other hands, with a +consequent delay in its commencement. + +My ignorance of the unfortunate peculiarity displayed by rabbits in not +throwing intermediate characters has led to a further waste of time in +another line of experiment. On finding that mammalian ovaries did not +admit of being grafted, it seemed to me that the next best thing to try +would be the transplantation of fertilized ova from one variety to +another, for the purpose of ascertaining whether, if a parturition +should take place under such circumstances, gestation by the uterine +mother would affect the characters of the ovum derived from the ovarian +mother--she, of course, having been fertilized by a male of her own +variety. Of course it was necessary that both the mothers should be in +season at about the same time, and therefore I again chose rabbits, +seeing that in the breeding season they are virtually in a chronic state +of "heat." I selected Himalayans and Belgian hares, because they are +well-marked varieties, breed true, and in respect of colour are very +different from one another. It so happened that while I was at work upon +this experiment, it was also being tried, unknown to me, by Messrs. +Heape and Buckley who, curiously enough, employed exactly the same +material. They were the first to obtain a successful result. Two +fertilized ova of the Angora breed having been introduced into the +fallopian tube of a Belgian hare, developed there in due course, and +gave rise to two Angora rabbits in no way modified by their Belgian hare +gestation[83]. + + [83] _Proc. R. S. 1890_, vol. xlviii. p. 457. It should be stated + that the authors do not here concern themselves with any theory + of heredity. + +But, interesting and suggestive as this experiment is in other +connexions, it is clearly without significance in the present one, for +the reason already stated. It will have to be tried on well-marked +varieties of other species of animals, which are known to throw +intermediate characters. Even, however, if it should then yield a +similarly negative result, the fact would not tell against the +inheritance of acquired characters; seeing that an ovum by the time it +is ripe is a finished product, and therefore not to be expected, on any +theory of heredity, to be influenced as to its hereditary potentialities +by the mere process of gestation. On the other hand, if it should prove +that it does admit of being thus affected, so that against all +reasonable expectation the young animal presents any of the hereditary +characters of its uterine mother, the fact would terminate the question +of the transmission of acquired characters--and this quite as +effectually as would a similarly positive result in the case of progeny +from an ingrafted ovary of a different variety. In point of fact, the +only difference between the two cases would be, that in the former it +_might_ prove possible to close the question on the side of +Lamarckianism, in the latter it would _certainly_ close the question, +either on this side or on the opposite as the event would determine. + +The only additional fact that has hitherto been published by the school +of Weismann is the result of Weismann's own experiment in cutting off +the tails of mice through successive generations. But this experiment +does not bear upon any question that is in debate; for no one who is +acquainted with the literature of the subject would have expected any +positive result to follow from such a line of inquiry. As shown further +back in the text, Darwin had carefully considered the case of +mutilations, and explained that their non-transmissibility constitutes +no valid objection to his theory of pangenesis. Furthermore, it may now +be added, he expressly alluded in this connexion to the cutting off of +tails, as practised by horse-breeders and dog-fanciers, "through a +number of generations, without any inherited effect." He also alluded to +the still better evidence which is furnished by the practice of +circumcision. Therefore it is difficult to understand the object of +Weismann's experiment. Yet, other than the result of this experiment, no +new fact bearing on the question at issue has been even so much as +alleged. + + + + +CHAPTER VI. + +CHARACTERS AS HEREDITARY AND ACQUIRED +(_conclusion_[84]). + + [84] _See_ note appended to Preface. C. Ll. M. + +In the foregoing chapters I have endeavoured to be, before all things, +impartial; and if it seems that I have been arguing chiefly in favour of +the Lamarckian principles, this has been because the only way of +examining the question is to consider what has to be said on the +affirmative side, and then to see what the negative side can say in +reply. Before we are entitled to discard the Lamarckian factors _in +toto_, we must be able to destroy all evidence of their action. This, +indeed, is what the ultra-Darwinians profess to have done. But is not +their profession premature? Is it not evident that they have not +sufficiently considered certain general facts of nature, or certain +particular results of experiment, which at all events appear +inexplicable by the theory of natural selection alone? In any case the +present discussion has been devoted mainly to indicating such general +facts and particular results. If I have fallen into errors, either of +statement or of reasoning, it is for the ultra-Darwinians to correct +them; but it may be well to remark beforehand, that any criticism of a +merely general kind touching the comparative paucity of the facts thus +adduced in favour of Lamarckian doctrine, will not stand as a valid +criticism. For, as we have seen in the opening part of the discussion, +even if use-inheritance and direct action of the environment have been +of high importance as factors of organic evolution, it must be in almost +all cases impossible to dissociate their influence from that of natural +selection--at any rate where plants and animals in a state of nature are +concerned. On the other hand, experiments expressly devised to test the +question have not hitherto been carried out. Besides, the facts and +arguments here adduced are but _comparatively_ few. For, unless it can +be shown that what has been said of reflex action, instinct, so-called +"self-adaptation" in plants, &c., is wrong in principle, the facts which +tell in favour of Lamarckian theory are _absolutely_ very numerous. Only +when considered in relation to cases where we are unable to exclude the +conceivable possibility of natural selection having been at work, can it +be said that the facts in question are not numerous. + +Comparatively few, then, though the facts may be of which I have given +some examples, in my opinion they are amply sufficient for the purpose +in hand. This purpose is to show that the question which we are now +considering is very far from being a closed question; and, therefore, +that the school of Weismann is much too precipitate in alleging that +there is neither any necessity for, nor evidence of, the so-called +Lamarckian factors[85]. And this opinion, whatever it may be worth, is +at all events both deliberate and impartial. As one of the first to +doubt the transmission of acquired characters, and as one who has spent +many years in experimental inquiries upon the subject, any bias that I +may have is assuredly against the Lamarckian principles--seeing that +nearly all my experiments have yielded negative results. It was Darwin +himself who checked this bias. But if the ultra-Darwinians of the last +ten years had succeeded in showing that Darwin was mistaken, I should be +extremely glad to fall into line with them. As already shown, however, +they have in no way affected this question as it was left by Galton in +1875. And if it be supposed a matter of but little importance whether we +agree with Galton in largely diminishing the comparative potency of the +Lamarckian principles, or whether we agree with Weismann in abolishing +them together, it cannot be too often repeated that such is an entirely +erroneous view. No matter how faintly or how fitfully acquired +characters may be transmitted, in so far as they are likewise adaptive +characters, their transmission (and therefore their development) must be +cumulative. Hence, the only effect of attenuating our estimate of their +_intensity_, is that of increasing our estimate of their +_duration_--i.e. of the time over which they have to operate in order to +produce important results. And, even so, it is to be remembered that +the importance of such results is not to be estimated by the magnitude +of modification. Far more is it to be estimated by the character of +modification as adaptive. For if functionally produced changes, and +changes produced in adaptive response to the environment, are ever +transmitted in a cumulative manner, a time must sooner or later arrive +when they will reach a selective value in the struggle for +existence--when, of course, they will be rapidly augmented by natural +selection. Thus, if in any degree operative at all, the great function +of these principles must be that of supplying to natural selection those +incipient stages of adaptive modifications in all cases where, but for +their agency, there would have been nothing of the kind to select. +Themselves in no way dependent on adaptive modifications having already +attained a selective value, these Lamarckian principles are (under the +Darwinian theory) direct causes of determinate variation in adaptive +lines; and variation in those lines being cumulative, the result is that +natural selection is in large part presented with the raw material of +its manufacture--special material of the particular kinds required, as +distinguished from promiscuous material of all kinds. And the more +complex the manufacture the more important will be the work of this +subordinate factory. We can well imagine how the shell of a nut, for +instance, or even the protective colouring of an insect, may have been +gradually built up by natural selection alone. But just in proportion as +structures or organs are not merely thus of passive _use_ (where, of +course, the Lamarckian principles cannot obtain), but require to be +actively _used_, in that proportion does it become difficult to +understand the _incipient_ construction of them by natural selection +alone. Therefore, in many such cases, if the incipient construction is +not to be explained by the Lamarckian principles, it is difficult to see +how it is to be explained at all. + + [85] E.g. "The supposed transmission of this artificially produced + disease (epilepsy) is the only definite instance which has been + brought forward in support of the transmission of acquired + characters."--_Essays_, p. 328. + +Furthermore, since the question as to the transmission of acquired +characters stands now exactly as it did after the publication of Mr. +Galton's _Theory of Heredity_ twenty years ago, it would seem that our +judgement with regard to it should remain exactly what it was then. +Although we must "out-Darwin Darwin" to the extent of holding that he +assigned too large a measure of intensity to the Lamarckian factors, no +sufficient reason has been shown for denying the existence of these +factors _in toto_; while, on the other hand, there are certain general +considerations, and certain particular facts, which appear to render it +probable that they have played a highly important part in the process of +organic evolution as a whole. At the same time, and in the present state +of our information, this judgement must be deemed provisional, or liable +eventually to be overturned by experimental proof of the non-inheritance +of acquired characters. But, even if this should ever be finally +accomplished, the question would still remain whether the principle of +natural selection alone is capable of explaining all the facts of +adaptation; and, for my own part, I should then be disposed to believe +that there must be some other, though hitherto undiscovered, principle +at work, which co-operates with natural selection, by playing the +subordinate role which was assigned by Darwin to the principles of +Lamarck. + +Finally, let it be noted that no part of the foregoing argument is to be +regarded as directed against the _principle_ of what Professor Weismann +calls "continuity." On the contrary, it appears to be self-evident that +this principle must be accepted in some degree or another by every one, +whether Darwinians, Neo-Darwinians, Lamarckians, Neo-Lamarckians, or +even the advocates of special creation. Yet, to hear or to read some of +the followers of Weismann, one can only conclude that, prior to his +publications on the subject, they had never thought about it at all. +These naturalists appear to suppose that until then the belief of +Darwinians was, that there could be no hereditary "continuity" between +any one organic type and another (such, for instance, as between Ape and +Man), but that the whole structure of any given generation must be due +to "gemmules" or "somato-plasm," derived exclusively from the preceding +generation. Nothing can show more ignorance, or more thoughtlessness, +with regard to the whole subject. The very basis of the general theory +of evolution is that there must always have been a continuity in the +material substance of heredity since the time when the process of +evolution began; and it was not reserved for our generation, or even for +our century, to perceive the special nature of this material substance +in the case of sexual organisms. No, the real and the sole question, +where Weismann's theory of heredity is concerned, is simply this--Are we +to hold that this material substance has been _absolutely_ continuous +"since the first origin of sexual propagation," always occupying a +separate "sphere" of its own, at all events to the extent of never +having been modified by the body substance in which it resides +(Lamarckian factors); _or_, are we to hold that this "germ-plasm," +"stirp," or "formative-material," has been but _relatively_ continuous, +so as to admit of some amount of commerce with body-substance, and +therefore to admit of acquired characters, when sufficiently long +continued as such, eventually becoming congenital? If this question be +answered in the latter sense, of course the further question arises as +to the _degree_ of such commerce, or the _time_ during which acquired +characters must continue to be acquired in successive generations before +they can sufficiently impress themselves on the substance of heredity to +become congenital. But this is a subordinate question, and one which, in +the present state of our information, it seems to me almost useless to +speculate upon. My own opinion has always been the same as that of Mr. +Galton; and my belief is that eventually both Weismann and his followers +will gravitate into it. It was in order to precipitate this result as +far as possible that I wrote the _Examination_. If it ever should be +accomplished, Professor Weismann's elaborate theory of evolution will +have had its bases removed. + + + + +SECTION II + +_UTILITY_ + + + + +CHAPTER VII. + +CHARACTERS AS ADAPTIVE AND SPECIFIC. + + +One of the great changes which has been wrought in biological science by +the Darwinian theory of natural selection, consists in its having +furnished an intelligible explanation of the phenomena of _adaptation_. +Indeed, in my opinion, this is the most important function which this +theory has had to perform; and although we still find systematic +zoologists and systematic botanists who hold that the chief merit of +Darwin's work consists in its having furnished an explanation of the +origin of _species_, a very little consideration is enough to show that +such an idea is but a survival, or a vestige, of an archaic system of +thought. So long as species were regarded as due to separate acts of +creation, any theory which could explain their production by a process +of natural evolution became of such commanding importance in this +respect, that we cannot wonder if in those days the principal function +of Darwin's work was held to be what the title of that work--_The Origin +of Species by means of Natural Selection_--itself serves to convey. And, +indeed, in those days this actually was the principal function of +Darwin's work, seeing that in those days the _fact_ of evolution +itself, as distinguished from its _method_, had to be proved; and that +the whole proof had to stand or fall with the evidence which could be +adduced touching the mutability of species. Therefore, without question, +Darwin was right in placing this issue as to the stability or +instability of species in the forefront of his generalizations, and +hence in constituting it the title of his epoch-making book. But +nowadays, when the fact of evolution has been sufficiently established, +one would suppose it self-evident that the theory of natural selection +should be recognized as covering a very much larger field than that of +explaining the origin of _species_--that it should be recognized as +embracing the whole area of organic nature in respect of _adaptations_, +whether these happen to be distinctive of species only, or of genera, +families, orders, classes, and sub-kingdoms. For it follows from the +general fact of evolution that species are merely arbitrary divisions, +which present no deeper significance from a philosophical point of view +than is presented by well-marked varieties, out of which they are in all +cases believed to have arisen, and from which it is often a matter of +mere individual taste whether they shall be separated by receiving the +baptism of a specific name. Yet, although naturalists are now +unanimously agreed that what they classify as species are nothing +more than pronounced--and in some greater or less degree +permanent--varieties, so forcible is the influence of traditional modes +of thought, that many zoologists and botanists still continue to regard +the origin of species as a matter of more importance than the origin of +adaptations. Consequently, they continue to represent the theory of +natural selection as concerned, primarily, with explaining the origin of +species, and denounce as a "heretic" any one who regards the theory as +primarily a theory of the origin and cumulative development of +adaptations--whether structural or instinctive, and whether the +adaptations are severally characteristic of species only or of any of +the higher taxonomic divisions. Indeed, these naturalists appear to deem +it in some way a disparagement of the theory to state that it is, +primarily, a theory of adaptations, and only becomes secondarily a +theory of species in those comparatively insignificant cases where the +adaptations happen to be distinctive of the lowest order of taxonomic +division--a view of the matter which may fitly be compared to that of an +astronomer who should define the nebular hypothesis as a theory of the +origin of Saturn's rings. It is indeed a theory of the origin of +Saturn's rings; but only because it is a theory of the origin of the +entire solar system, of which Saturn's rings form a part. Similarly, the +theory of natural selection is a theory of the entire system of organic +nature in respect of adaptations, whether these happen to be distinctive +of particular species only, or are common to any number of species. + +Now the outcry which has been raised over this definition of the theory +of natural selection is a curious proof of the opposition which may be +furnished by habitual modes of thought to an exceedingly plain matter of +definition. For, I submit, that no one can deny any of the following +propositions; nor can it be denied that from these propositions the +foregoing definition of the theory in question follows by way of +necessity. The propositions are, first, that natural selection is taken +to be the agency which is mainly, if not exclusively, concerned in the +evolution of adaptive characters: secondly, that these characters, when +evolved, are in some cases peculiar to single species only, while in +other cases, and in process of time, they become the common property of +many species: thirdly, that in cases where they are peculiar to single +species only, they constitute at all events one of the reasons (or even, +as the ultra-Darwinians believe, the only reason) why the particular +species presenting them have come to be species at all. Now, these being +the propositions on which we are all agreed, it obviously follows, of +logical necessity, that the theory in question is primarily one which +explains the existence of adaptive characters wherever these occur; and, +therefore, whether they happen to be restricted to single species, or +are common to a whole group of species. Of course in cases where they +are restricted to single species, the theory which explains the origin +of these particular adaptations becomes also a theory which explains the +origin of these particular species; seeing that, as we are all agreed, +it is in virtue of such particular adaptations that such particular +species exist. Yet even in these cases the theory is, primarily, a +theory of the adaptations in virtue of which the particular species +exists; for, _ex hypothesi_, it is the adaptations which condition the +species, not the species the adaptations. But, as just observed, +adaptations may be the common property of whole groups of species; and +thus the theory of natural selection becomes a theory of the origin of +genera, of families, of orders, and of classes, quite as much as it is a +theory of the origin of species. In other words, it is everywhere a +theory of adaptations; and it is only where the adaptations happen to be +restricted to single species that the theory therefore and incidentally +becomes also a theory of the particular species which presents them. +Hence it is by no means the same proposition to affirm that the theory +of natural selection is a theory of the origin of species, and that it +is a theory of the origin of adaptations, as some of my critics have +represented it to be; for these two things are by no means conterminous. +And in as far as the two propositions differ, it is perfectly obvious +that the latter is the true one. + +Possibly, however, it may be said--Assuredly natural selection is a +theory of the origin (i.e. cumulative development) of adaptations; and, +no less assuredly, although species owe their origin to such +adaptations, there is now no common measure between these two things, +seeing that in numberless cases the same adaptations are the common +property of numberless species. But, allowing all this, we must still +remember that in their _first beginnings_ all these adaptations must +have been distinctive of, or peculiar to, some one particular species, +which afterwards gave rise to a whole genus, family, order, or class of +species, all of which inherited the particular adaptations derived from +this common ancestor, while progressively gaining additional adaptive +characters severally distinctive of their subsequently diverging lines +of descent. So that really all adaptive characters must originally have +been specific characters; and therefore there is no real distinction to +draw between natural selection as a theory of species and as a theory of +adaptations. + +Well, if this objection were to be advanced, the answer would be +obvious. Although it is true that every adaptive character which is now +common to a group of species must originally have been distinctive of a +single parent species, it by no means follows that in its first +beginning as a specific character it appeared in the fully developed +form which it now presents as a generic, family, ordinal, or yet higher +character. On the contrary, it is perfectly certain that in the great +majority of instances such cannot possibly have been the case; and the +larger the group of species over which any particular adaptive character +now extends, the more evidently do we perceive that this character must +itself have been the product of a gradual evolution by natural selection +through an innumerable succession of species in branching lines. The +wing of a bird, for example, is an adaptive structure which cannot +possibly have ever appeared suddenly as a merely specific character: it +must have been slowly elaborated through an incalculable number of +successive species, as these branched into genera, families, and orders +of the existing class. So it is with other class distinctions of an +adaptive kind; and so, in progressively lessening degrees, is it with +adaptive characters of an ordinal, a family, or a generic value. That is +to say, in _all_ cases where an adaptive structure is common to any +considerable group of species, we meet with clear evidence that the +structure has been the product of evolution through the ancestry of +those species; and this evidence becomes increasingly cogent the higher +the taxonomic value of the structure. Indeed, it may be laid down as a +general rule, that the greater the _degree_ of adaptation the greater is +its _diffusion_--both as regards the number of species which present it +now, and the number of extinct species through which it has been handed +down, in an ever ramifying extension and in an ever improving form. +Species, therefore, may be likened to leaves: successive and transient +crops are necessary for the gradual building up of adaptations, which, +like the woody and permanent branches, grow continuously in importance +and efficiency through all the tree of life. Now, in my view, it is the +great office of natural selection to see to the growth of these +permanent branches; and although natural selection has likewise had an +enormously large share in the origination of each successive crop of +leaves--nay, let it be granted to the ultra-Darwinians for the sake of +argument, an exclusive prerogative in this respect--still, in my view, +this is really the least important part of its work. Not as an +explanation of those merely permanent varieties which we call species, +but as an explanation of the adaptive machinery of organic nature, which +has led to the construction both of the animal and vegetable kingdoms in +all their divisions do I regard the Darwinian theory as one of the +greatest generalizations in the history of science. + + * * * * * + +I have dwelt thus at some length upon a mere matter of definition +because, as we shall now find, although it is but a matter of +definition, it is fraught with consequences of no small importance to +the general theory of descent. Starting from an erroneous definition of +the theory of natural selection as primarily a theory of the origin of +species, both friends and foes of the theory have concluded that the +principle of utility must by hypothesis be of universal occurrence so +far as species are concerned; whereas, if once these naturalists were to +perceive that their definition of the theory is erroneous, they would +likewise perceive that their conclusion cannot follow deductively from +the theory itself. If such a conclusion is to be established at all, it +can only be by other and independent evidence of the inductive kind--to +wit, by actual observation. + +Hence we see the importance of starting with an accurate definition of +the theory before proceeding to examine the doctrine of utility as of +universal application to species--a doctrine which, as just stated, has +been habitually and expressly deduced from the theory. This doctrine +occurs in two forms; or, more correctly, there are with reference to +this subject two distinct doctrines, which partly coincide and partly +exclude one another. First, it is held by some naturalists that all +species must necessarily owe their origin to natural selection. And +secondly, it is held by other naturalists, that not only all species, +but likewise all specific characters must necessarily do the same. Let +us consider these two doctrines separately. + +The first, and less extensive doctrine, rests on the deduction that +every species must owe its differentiation as a species to the evolution +of at least one adaptive character, which is peculiar to that species. +Although, when thus originated, a species may come to present any +number of other peculiar characters of a non-adaptive kind, these merely +indifferent peculiarities are supposed to hang, as it were, on the peg +supplied by the one adaptive peculiarity; it is the latter which +conditions the species, and so furnishes an opportunity for any number +of the former to supervene. But without the evolution of at least one +adaptive character there could have been no distinct species, and +therefore no merely adventitious characters as belonging to that +species. I will call this the Huxleyan doctrine, because Professor +Huxley is its most express and most authoritative supporter. + +The second and more extensive doctrine I will call, for the same reason, +the Wallacean doctrine. This is, as already stated, that it follows +deductively from the theory of natural selection, that not only all +species, but even all the distinctive characters of every species, must +necessarily be due to natural selection; and, therefore, can never be +other than themselves useful, or, at the least, correlated with some +other distinctive characters which are so. + +Here, however, I should like to remark parenthetically, that in choosing +Professor Huxley and Mr. Wallace as severally representative of the +doctrines in question, I earnestly desire to avoid any appearance of +discourtesy towards such high authorities. + +I am persuaded--as I shall hereafter seek to show Darwin was +persuaded--that the doctrine of utility as universal where species are +concerned, is, in both the above forms, unsound. But it is less +detrimental in its Huxleyan than in its Wallacean form, because it does +not carry the erroneous deduction to so extreme a point. Therefore let +us first consider the doctrine in its more restricted form, and then +proceed, at considerably greater length, to deal with it in its more +extended form. + + * * * * * + +The doctrine that all _species_ must necessarily be due to natural +selection, and therefore must severally present at least one adaptive +character, appears to me doubly erroneous. + +In the first place, it is drawn from what I have just shown to be a +false premiss; and, in the second place, the conclusion does not follow +even from this premiss. That the premiss--or definition of the theory as +primarily a theory of the origin of species--is false, I need not wait +again to argue. That the conclusion does not follow even from this +erroneous premiss, a very few words will suffice to prove. For, even if +it were true that natural selection is primarily a theory of the origin +of species, it would not follow that it must therefore be a theory of +the origin of _all_ species. This would only follow if it were first +shown that the theory is not merely _a_ theory of the origin of species, +but _the_ theory of the origin of species--i.e. that there can be no +further theory upon this subject, or any cause other than natural +selection which is capable of transforming any single specific type. + +Needless to say, this cannot be shown by way of deduction from the +theory of natural selection itself--which, nevertheless, is the only way +whereby it is alleged that the doctrine is arrived at[86]. + + [86] For a full treatment of Professor Huxley's views upon this + subject, see Appendix II. + + * * * * * + +From the doctrine of utility as advocated by Professor Huxley, we may +now pass on to consider it in the much more comprehensive form advocated +by Mr. Wallace. Of course it is obvious that if the doctrine is +erroneous in its Huxleyan form, much more must it be so in its +Wallacean; and, therefore, that having shown its erroneousness in its +less extended application, there is little need to consider it further +in its more extended form. Looking, however, to its importance in this +more extended application, I think we ought to examine it independently +as thus presented by Mr. Wallace and his school. Let us therefore +consider, on its own merits, the following statement:--It follows +directly from the theory of natural selection that not only all species, +but likewise all specific characters, must be due to natural selection, +and, therefore, must all be of use to the species which present them, or +else correlated with other characters which are so. + +It seems worth while to observe, _in limine_, that this doctrine is +contradicted by that of Professor Huxley. For supposing natural +selection to be the only principle concerned in the origin of all +species, it by no means follows that it is the sole agency concerned in +the origin of all specific characters. It is enough for the former +proposition if only some of the characters distinctive of any given +species--nay, as he very properly expresses it, if only one such +character--has been due to natural selection; for it is clear that, as +he adds, "any number of indifferent [specific] characters" may thus have +been furnished with an opportunity, so to speak, of being produced by +causes other than natural selection. Hence, as previously remarked, the +Huxleyan doctrine, although coinciding with the Wallacean up to the +point of maintaining utility as the only principle which can be +concerned in the origin of species, designedly excludes the Wallacean +doctrine where this proceeds to extend any similar deduction to the case +of specific characters[87]. + + [87] Professor Huxley's views upon this matter are quoted _in + extenso_ in Appendix II. + +In the next place, and with special reference to the Wallacean doctrine, +it is of importance to observe that, up to a certain point there is +complete agreement between Darwinists of all schools. We all accept +natural selection as a true cause of the origin of species (though we +may not all subscribe to the Huxleyan deduction that it is necessarily a +cause of the origin of _all_ species). Moreover, we agree that specific +characters are often what is called rudimentary or vestigial; and, once +more, that our inability to detect the use of any given structure or +instinct is no proof that such a structure or instinct is actually +useless, seeing that it may very probably possess some function hitherto +undetected, or possibly undetectable. Lastly, we all agree that a +structure which is of use may incidentally entail the existence of some +other structure which is not of use; for, in virtue of the so-called +principle of correlation, the useless structure may be an indirect +consequence of natural selection, since its development may be due to +that of the useful structure, with the growth of which the useless one +is correlated. + +Nevertheless, while fully conceding all these facts and principles to +the Wallacean party, those who think with Professor Huxley--and still +more, of course, those few naturalists who think as I do--are unable +to perceive that they constitute any grounds for holding the doctrine +that all specific _characters_ are, or formerly have been, directly or +indirectly due to natural selection. My own reasons for dissenting from +this Wallacean doctrine are as follows. + + * * * * * + +From what has just been said, it will be apparent that the question in +debate is not merely a question of fact which can be settled by a direct +appeal to observation. If this were the case, systematic naturalists +could soon settle the question by their detailed knowledge of the +structures which are severally distinctive of any given group of +species. But so far is this from being the case, that systematic +naturalists are really no better qualified to adjudicate upon the matter +than are naturalists who have not devoted so much of their time to +purely diagnostic work. The question is one of general principles, and +as such cannot be settled by appeals to special cases. For example, +suppose that the rest of this chapter were devoted to a mere enumeration +of cases where it appears impossible to suggest the utility of certain +specific characters, although such cases could be adduced by the +thousand, how should I be met at the end of it all? Not by any one +attempting to suggest the utility, past or present, of the characters +named; but by being told that they must all present some _hidden_ use, +must be _vestigial_, or else must be due to _correlation_. By appealing +to one or other of these assumptions, our opponents are always able to +escape the necessity of justifying their doctrine in the presence of +otherwise inexplicable facts. No matter how many seemingly "indifferent +characters" we may thus accumulate, Mr. Wallace and his followers will +always throw upon us the impossible burden of proving the negative, that +these apparently useless characters do _not_ present some hidden or +former use, are _not_ due to correlation, and therefore have _not_ been +produced by natural selection. It is in vain to retort that the burden +of proof really lies the other way, or on the side of those who affirm +that there is utility where no man can see it, or that there is +correlation where no one can detect it. Thus, so far as any appeal to +particular facts is concerned, it does not appear that there is any +_modus vivendi_. Our opinions upon the question are really determined by +the views which we severally take on matters of general principle. The +issue, though it has a biological bearing, is a logical issue, not a +biological one: it turns exclusively on those questions of definition +and deduction with which we have just been dealing. + +But although it thus follows that we cannot determine in fact what +proportion of apparently useless characters are or are not really +useful, we may very easily determine in fact what proportion of specific +characters _fail to present any observable evidences of utility_. Yet, +even upon this question of observable fact, it is surprising to note the +divergent statements which have of late years been made by competent +writers; statements in fact so divergent that they can only be explained +by some want of sufficient thought on the part of those naturalists who +are antecedently persuaded that all specific characters must be either +directly or indirectly due to natural selection. Hence they fail to give +to apparently useless specific characters the attention which, apart +from any such antecedent persuasion, they deserve. For example, a few +years ago I incidentally stated in a paper before the Linnaean Society, +that "a large proportional number of specific characters" are of a +trivial and apparently unmeaning kind, to which no function admits of +being assigned, and also stated that Darwin himself had expressly given +utterance to the same opinion. When these statements were made, I did +not anticipate that they would be challenged by anybody, except perhaps, +by Mr. Wallace. And, in order now to show that my innocence at that time +was not due to ignorance of contemporary thought on such matters, a +sentence may here be quoted from a paper which was read at the meeting +of the British Association of the same year, by a highly competent +systematic naturalist, Mr. Henry Seebohm, and soon afterwards +extensively republished. Criticizing adversely my then recently +published paper, he said:-- + + "I fully admit the truth of this statement; and I presume that few + naturalists would be prepared to deny that 'distinctions of + specific value frequently have reference to structures which are + without any utilitarian significance[88].'" + + [88] _Geographical Distribution of the Family Charadriidae_, p. 19. + +But since that time the course of Darwinian speculation has been greatly +influenced by the writings of Weismann, who, among other respects in +which he out-darwins Darwin, maintains the doctrine of utility as +universal. In consequence of the influence which these writings have +exercised, I have been more recently and extensively accused of "heresy" +to Darwinian principles, for having stated that "a large proportional +number of specific characters" do not admit of being proved useful, or +correlated with other characters that are useful. Now, observe, we have +here a simple question of fact. We are not at present concerned with the +question how far the argument from ignorance may be held to apply in +mitigation of such cases; but we are concerned only with the question of +fact, as to what proportional number of cases actually occur where we +are _unable to suggest_ the use of specific characters, or the useful +characters with which these apparently useless ones are correlated. I +maintain, as a matter of fact, that the cases in question embrace "a +large proportional number of specific characters." On the other hand, I +am accused of betraying ignorance of species, and of the work of +"species-makers," in advancing this statement; and have been told by Mr. +Wallace, and others of his school, that there is absolutely no evidence +to be derived from nature in support of my views. Well, in the first +place, if this be the case, it is somewhat remarkable that a large body +of competent naturalists, such as Bronn, Broca, Naegeli, Kerner, Sachs, +De Vries, Focke, Henslow, Haeckel, Koelliker, Eimer, Giard, Pascoe, +Mivart, Seebohm, Lloyd Morgan, Dixon, Beddard, Geddes Gulick, and also, +as we shall presently see, Darwin himself, should have fallen into the +same error. And it is further remarkable that the more a man devotes +himself to systematic work in any particular department--whether as an +ornithologist, a conchologist, an entomologist, and so forth--the less +is he disposed to accept the dogma of specific characters as universally +adaptive characters. But, in the second place, and quitting +considerations of mere authority, I appeal to the facts of nature +themselves; and will now proceed, as briefly as possible, to indicate +the result of such an appeal. + +For the following reasons, that birds and mammals seem to furnish the +best field for testing the question by direct observation. First, these +classes present many genera which have been more carefully worked out +than is usually the case with genera of invertebrates, or even of +cold-blooded vertebrates. Secondly, they comprise many genera each +including a large number of species, whose habits and conditions of life +are better known than is the case with species belonging to large genera +of other classes. Thirdly, as birds and mammals represent the highest +products of evolution in respect of organization, a more severe test is +imposed than could be imposed elsewhere, when the question is as to the +utility of specific characters; for if these highest products of +organization fail to reveal, in a large proportional number of cases, +the utility of their specific characters, much more is this likely to be +the case among organic beings which stand lower in the scale of +organization, and therefore, _ex hypothesi_, are less elaborate products +of natural selection. Fourthly, and lastly, birds and mammals are the +classes which Mr. Wallace has expressly chosen to constitute his ground +of argument with regard to the issue on which we are now engaged. + +It would take far too long to show, even in epitome, the results of this +inquiry. Therefore I will only state the general upshot. Choosing genera +of birds and mammals which contain a large number of species whose +diagnostic characters have been worked out with most completeness, I +restricted the inquiry to specific distinctions of colour, not only for +the sake of having a uniform basis for comparisons, but still more +because it seemed that the argument from our ignorance of possibly +unknown uses could be more successfully met in the case of slight +differences of colour or of shading, than in that of any differences of +structure or of form. Finally, after tabulating all the differences of +colour which are given as diagnostic of each species in a genus, and +placing in one column those which may conceivably be useful, while +placing in another column those of which it appeared inconceivable that +any use could be suggested, I added up the figures in the two columns, +and thus obtained a grand total of all the specific characters of the +genus in respect of colours, separated into the two classes of +conceivably useful and apparently useless. Now, in all cases the +apparently useless characters largely preponderated over the conceivably +useful ones; and therefore I abundantly satisfied myself regarding the +accuracy of my previous statement, that a large proportional number--if +not an actual majority--of specific characters belong to the latter +category. + +The following is a brief abstract of these results. + +With respect to Birds, a large number of cases were collected wherein +the characters of allied species differ from one another in such minute +respects of colour or shading, that it seemed unreasonable to suppose +them due to any selective value to the birds in question. It is +needless--even if it were practicable on the present occasion--to +adduce this evidence in detail, since an exceedingly good sample of it +may be found in a small book which is specially devoted to considering +the question in its relation to birds. I allude to an essay by Mr. +Charles Dixon, entitled _Evolution without Natural Selection_ (1885). In +this work Mr. Dixon embodies the results of five years' "careful working +at the geographical distribution and variations of plumage of +Palaearctic birds and their allies in various other parts of the world"; +and shows, by a large accumulation of facts, not only that there is no +utility to be suggested in reference to the minute or trivial +differences of colouration which he describes; but also that these +differences are usually correlated with isolation on the one hand, or +with slight differences of climate on the other. Now it will be shown +later on that both these agents can be proved, by independent evidence, +capable of inducing changes of specific type without reference to +utility: therefore the correlation which Mr. Dixon unquestionably +establishes between apparently useless (because utterly trivial) +specific distinctions on the one hand, and isolation or climatic change +on the other, constitutes additional evidence to show that the +uselessness is not only apparent, but real. Moreover I have collected a +number of cases where such minute differences of colour between allied +species of birds happen to affect parts of the plumage which are +_concealed_--as for instance, the breast and abdomen of creepers. In +such cases it seems impossible to suggest how natural selection can have +operated, seeing that the parts affected are not exposed to the view +either of enemies or of prey. + +Analogous illustrations to any amount may be drawn from Mammals. For +instance, I have worked through the Marsupials with the aid of Mr. +Oldfield Thomas' diagnostic description of their numerous species. Now, +let us take any one of the genera, such as the kangaroos. This comprises +23 species living on an island continent of high antiquity, and not +exposed to the depredations of any existing carnivorous enemies; so that +there is here no present need to vary colour for purposes of protection. +Moreover, in all cases the diagnostic distinctions of colour are so +exceedingly trivial, that even if large carnivora were recently abundant +in Australia, no one could reasonably suggest that the differences in +question would then have been protective. On an average, each of the 23 +species presents rather more than 20 peculiarities of shading, which are +quoted as specifically diagnostic. Altogether there are 474 of these +peculiarities distributed pretty evenly among the 23 species; and in no +case can I conceive that utility can be suggested. + + * * * * * + +Hitherto we have been considering the question of fact, as to whether "a +large proportional number of specific characters" do or do not admit of +having their utility demonstrated, or even so much as plausibly +suggested. In the result, I can only conclude that this question of fact +is really not an open one, seeing that it admits of an abundantly +conclusive answer by any naturalist who will take the trouble to work +through the species of any considerable number of genera in the way +above indicated. But although the question of fact is thus really +closed, there remains a more ultimate question as to its theoretical +interpretation. For, as already pointed out, no matter how great an +accumulation of such facts may be collected, our opponents are always +able to brush them aside by their _a priori_ appeal to the argument from +ignorance. In effect they say--We do not care for any number of +thousands of such facts; it makes no difference to us what "proportional +number" of specific characters fail to show evidence of utility; you are +merely beating the air by adducing them, for we are already persuaded, +on antecedent grounds, that _all_ specific characters _must_ be either +themselves useful, or correlated with others that are, whether or not we +can perceive the utility, or suggest the correlation. + +To this question of theoretical interpretation, therefore, we must next +address ourselves. And here, first of all, I should like to point out +how sturdy must be the antecedent conviction of our opponents, if they +are to maintain it in the face of such facts as have just been adduced. +It must be remembered that this antecedent conviction is of a most +uncompromising kind. By its own premisses it is committed to the +doctrine that _all_ specific characters, without a single exception, +_must_ be either useful, vestigial, or correlated. Well, if such be the +case, is it not somewhat astonishing that out of 474 differences of +colour which are distinctive of the 23 species of the genus Macropus, no +single one appears capable of having any utility demonstrated, or indeed +so much as suggested? For even the recent theory that slight differences +of colour, which cannot be conceived as serving any other purpose, may +enable the sexes of the same species quickly to recognize each other, is +not here available. The species of the genus Macropus are more +conspicuously distinguished by differences of size and form than by +these minute differences of colour; and therefore no such use can be +attributed to the latter. And, as previously stated, even within the +order Marsupialia the genus Macropus is not at all exceptional in this +respect; so that by including other genera of the order it would be easy +to gather such apparently indifferent specific characters by the +hundred, without any one of them presenting evidence--or even +suggestion--of utility. How robust therefore is the faith of an _a +priori_ conviction which can stand against such facts as these! What, +then, are the _a priori_ grounds on which it stands? Mr. Wallace, the +great leader of this school of thought, says:-- + + "It is a necessary deduction from the theory of natural selection, + that none of the definite facts of organic nature, no special + organ, no characteristic form or marking, no peculiarities of + instinct or of habit, no relations between species or between + groups of species, can exist, but which must now be, or once have + been, _useful_ to the individuals or the races which possess + them[89]." + + [89] _Contributions to the Theory of Natural Selection_, p. 47 + (1870); republished in 1892. + +Here, then, we have in brief compass the whole essence of our opponents' +argument. It is confessedly an argument _a priori_, a deduction from the +theory of natural selection, a supposed consequence of that theory which +is alleged to be so necessary that to dispute the consequence is +tantamount to denying the theory from which it is derived. In short, as +before stated, it is a question of theory, not a question of fact: our +difference of opinion is logical, not biological: it depends on our +interpretation of principles, not on our observation of species. It will +therefore be my endeavour to show that the reasoning in question is +fallacious: that it is _not_ a necessary deduction from the theory of +natural selection that no characteristic form or marking, no +peculiarities of instinct or of habit, can exist, but which must now be, +or once have been, useful, or correlated with some other peculiarity +that is useful. + +"The tuft of hair on the breast of a wild turkey-cock _cannot be of any +use_, and it is doubtful whether it can be ornamental in the eyes of the +female bird;--indeed, had the tuft appeared under domestication, it +would have been called a monstrosity[90]." + + [90] _Origin of Species_, p. 70: italics mine. + +As a matter of common sense, unprejudiced by dogma, this appears to be a +perfectly sound judgement; but if Wallace had asked Darwin to prove such +a negative, Darwin could only have replied that it was for Wallace to +prove the affirmative--and thus the issue would have been thrown back +upon a discussion of general principles. Then Wallace would have +said--"The assertion of inutility in the case of any organ or +peculiarity which is not a rudiment or a correlation _is not, and can +never be_, the statement of a fact, but _merely an expression of our +ignorance of its purpose or origin_[91]." Darwin, however, would have +replied:--"Our ignorance of the laws of variation is profound"; and +while, on this account, we ought "to be extremely cautious in +_pretending to decide what structures are now, or have formerly been, of +use to each species_," in point of fact "there can be little doubt that +the tendency to vary in the same manner has _often_ been so strong, that +_all_ individuals of the same _species_ have been similarly modified +_without the aid of any form of selection_[92]." + + [91] _Darwinism_, p. 137: italics mine. + + [92] _Origin of Species_, p. 72: Mr. Wallace himself quotes this + passage (_Darwinism_, p. 141); but says with regard to it "the + important word 'all' is probably an oversight." In the Appendix + (II), on Darwin's views touching the doctrine of utility I + adduce a number of precisely equivalent passages, derived from + all his different works on evolution, and _every one of them_ + presenting "the important word 'all.'" + +It will be my endeavour in the following discussion to show that Darwin +would have had an immeasurable advantage in this imaginary debate. + +To begin with, Wallace's deductive argument is a clear case of circular +reasoning. We set out by inferring that natural selection is a cause +from numberless cases of observed utility as an effect: yet, when "in a +large proportional number" of cases we fail to perceive any imaginable +utility, it is argued that nevertheless utility must be there, since +otherwise natural selection could not have been the cause. + +Be it observed, in any given case we may properly anticipate utility as +_probable_, even where it is not perceived; because there are already so +enormous a number of cases where it is perceived, that, if the principle +of natural selection be accepted at all, we must conclude with Darwin +that it is "the _main_ means of modification." Therefore, in particular +cases of unperceived utility we may take this antecedent probability as +a guide in our biological researches--as has been done with such +brilliant success both by Darwin and Wallace, as well as by many of +their followers. But this is a very different thing from laying down the +universal maxim, that in _all_ cases utility _must_ be present, whether +or not we shall ever be able to detect it[93]. For this universal maxim +amounts to an assumption that natural selection has been the +"_exclusive_ means of modification." That it has been "the main means of +modification" is proved by the generality of the observed facts of +adaptation. That it has been "the exclusive means of modification," with +the result that these facts are universal, cannot be thus proved by +observation. Why, then, is it alleged? Confessedly it is alleged by way +of deduction from the theory of natural selection itself. Or, as above +stated, after having deduced the theory from the facts, it is sought to +deduce the facts from the theory. + + [93] See Introductory Chapter, p. 20. + +Thus far I have been endeavouring to show that the universality of +adaptation cannot be inferred from its generality, or from the theory of +natural selection itself. But, of course, the case would be quite +different if there were any independent evidence--or rather, let us say, +any logical argument--to show that natural selection is "the exclusive +means of modification." For in this event it would no longer involve +circular reasoning to maintain that all specific characters are likewise +adaptive characters. It might indeed appear antecedently improbable that +no other principle than natural selection can possibly have been +concerned in the differentiation of those relatively permanent varieties +which we call species--that in all the realm of organic nature, and in +all the complexities of living processes, there is no room for any +other influence in the production of change, even of the most trivial +and apparently unmeaning kind. But if there were any good evidence or +logical argument to the contrary, this antecedent presumption would have +to give way; and the certainty that all specific characters are likewise +adaptive characters would be determined by the cogency of such evidence +or argument as could be adduced. In short, we are not entitled to +conclude--and still less does it follow "as a necessary deduction from +the theory of natural selection"--that all the details of specific +differentiation must in every case be either useful, vestigial, or +correlated, _unless it has been previously shown, by independent +evidence, or accurate reasoning, that there is no room for any other +principle of specific change_. + +This, apparently, is the central core of the question. Therefore I will +now proceed to consider such arguments as have been adduced to prove +that, other than natural selection, there _can_ have been no "means of +modification." And, after having exhibited the worthlessness of these +arguments, I will devote the next chapter to showing that, as a matter +of observable fact, there _are_ a considerable number of other +principles, which can be proved to be capable of producing such minute +differences of form and colour as "in a large proportional number" of +cases constitute diagnostic distinctions between species and species. + +First, then, for the reasons _a priori_--and they are confessedly _a +priori_--which have been adduced to prove that natural selection has +been what in Darwin's opinion it has not been,--"the _exclusive_ means +of modification." Disregarding the Lamarckian factors--which, even if +valid, have but little relation to the present question, seeing that +they are concerned, almost exclusively, with the evolution of _adaptive_ +characters--it is alleged that natural selection must occupy the whole +field, because no other principle of change can be allowed to operate in +the presence of natural selection. Now, I fully agree that this +statement may hold as regards any principle of change which is +deleterious; but clearly it does not hold as regards any principle which +is merely neutral. If any one were to allege that specific characters +are frequently detrimental to the species presenting them, he would no +doubt lay himself open to the retort that natural selection could not +allow such characters to persist; or, which amounts to the same thing, +that it _does_ "necessarily follow from the theory of natural selection" +that specific characters can never be in any large number, or in any +large measure, _harmful_ to the species presenting them. But where +the statement is that specific characters are frequently +_indifferent_--again to use Professor Huxley's term--the retort loses +all its relevancy. No reason has ever been shown why natural selection +should interfere with merely indifferent characters, supposing such to +have been produced by any of the agencies which we shall presently have +to consider. Therefore this argument--or rather assertion--goes for +nothing. + +The only other argument I have met with on this side of the question is +one that has recently been adduced by Mr. Wallace. He says:-- + + "One very weighty objection to the theory that _specific_ + characters can ever be wholly useless appears to have been + overlooked by those who have maintained the frequency of such + characters, and that is, their almost necessary instability[94]." + + [94] _Darwinism_, p. 138. + +This argument he proceeds to elaborate at considerable length, but fails +to perceive what appears to me the obvious answer. Provided that the +cause of the useless character is constant, there is no difficulty in +understanding why the character is stable. Utility is not the only +principle that can lead to stability: any other principle must do the +same, provided that it acts for a sufficient length of time, and with a +sufficient degree of uniformity, on all the individuals of a species. +This is a consideration the cogency of which was clearly recognized by +Darwin, as the following quotations will show. Speaking of unadaptive +characters, he says they may arise as merely + + "fluctuating variations, which sooner or later become _constant_ + through the nature of the organism and of surrounding conditions, + _but not through natural selection_[95]." + + [95] _Origin of Species_, p. 176: italics mine, as also in the + following. + +Elsewhere we read:-- + + "Each of the endless variations which we see in the plumage of our + fowls must have had some efficient cause; and if the _same_ cause + were to act _uniformly_ during a long series of generations on + _many_ individuals, _all_ probably would be modified in the same + manner." + +As special illustrations of this fact I may quote the following cases +from Darwin's works. + + "Dr. Bachman states that he has seen turkeys raised from the eggs + of wild species, lose their metallic tints, and become spotted in + the third generation. Mr. Yarrell many years ago informed me that + the wild ducks bred in St James' Park lost their true plumage + after a few generations. An excellent observer (Mr. Hewitt) ... + found that he could not breed wild ducks true for more than five or + six generations, as they proved so much less beautiful. The white + collar round the neck of the mallard became broader and more + irregular, and white feathers appeared in the duckling's wings + &c.[96]" + + [96] _Var._ vol. ii. p. 250. + +Now, such cases--to which numberless others might be added--prove that +even the subtle and inconspicuous causes incidental to domestication are +capable of inducing changes of specific character quite as great, and +quite as "stable," as any that in a state of nature are taken to +constitute specific distinctions. Yet there can here be no suggestion of +utility, inasmuch as the change takes place in the course of a few +generations, and therefore without leaving time for natural selection to +come into play--even if it ever could come into play among the sundry +domesticated birds in question. + +But the facts of domestication also make for the same conclusion in +another way--namely, by proving that when time enough _has_ been allowed +for the production of useless changes of greater magnitude, such changes +are not infrequently produced. And the value of this line of evidence is +that, great as are the changes, it is impossible that either natural or +artificial selection can have been concerned in their production. It +will be sufficient to give two examples--both with regard to structure. + +The first I will render in the words whereby it has already been stated +in my own paper on _Physiological Selection_, because I should like to +take this opportunity of answering Mr. Wallace's objection to it. + + "Elsewhere (_Origin of Species_, p. 158) Mr. Darwin points out that + modifications which appear to present obvious utility are often + found on further examination to be really useless. This latter + consideration, therefore, may be said to act as a foil to the one + against which I am arguing, namely, that modifications which appear + to be useless may nevertheless be useful. But here is a still more + suggestive consideration, also derived from Mr. Darwin's writings. + Among our domesticated productions changes of structure--or even + structures wholly new--not unfrequently arise, which are in every + way analogous to the apparently useless distinctions between wild + species. Take, for example, the following most instructive case:-- + + [Illustration: Fig. 2.--Old Irish Pig, showing jaw-appendages + (after Richardson).] + + "'Another curious anomaly is offered by the appendages described by + M. Eudes-Deslongchamps as often characterizing the Normandy pigs. + These appendages are always attached to the same spot, to the + corners of the jaws; they are cylindrical, about three inches in + length, covered with bristles, and with a pencil of bristles rising + out of a sinus on one side; they have a cartilaginous centre with + two small longitudinal muscles; they occur either symmetrically on + both sides of the face, or on one side alone. Richardson figures + them on the gaunt old Irish Greyhound pig; and Nathusius states + that they occasionally appear in all the long-eared races, but are + not strictly inherited, for they occur or fail in the animals of + the same litter. As no wild pigs are known to have analogous + appendages, we have at present no reason to suppose that their + appearance is due to reversion; and if this be so, we are forced to + admit that a somewhat complex, though apparently useless, structure + may be suddenly developed without the aid of selection[97].'" + + [97] _Variation_, &c. vol. i. pp. 78-79. + +To this case Mr. Wallace objects:-- + + "But it is expressly stated that they are not constant; they appear + 'frequently' or 'occasionally,' they are 'not strictly inherited, + for they occur or fail in animals of the same litter'; and they are + not always symmetrical, sometimes appearing on one side of the face + alone. Now, whatever may be the cause or explanation of these + anomalous appendages, they cannot be classed with 'specific + characters,' the most essential features of which are, that they + _are_ symmetrical, that they _are_ inherited, and that they _are_ + constant[98]." + + [98] _Darwinism_, pp. 139-40. + +But, to begin with, I have not classed these appendages with "specific +characters," nor maintained that Normandy pigs ought to be regarded as +specifically distinct on account of them. What I said was:-- + + "Now, if any such structure as this occurred in a wild species, and + if any one were to ask what is the use of it, those who rely on the + argument from ignorance would have a much stronger case than they + usually have; for they might point to the cartilage supplied with + muscles, and supporting a curious arrangement of bristles, as much + too specialized a structure to be wholly meaningless. Yet we happen + to know that this particular structure is wholly meaningless[99]." + + [99] Mr. Wallace deems the concluding words "rather confident." I + was not, however, before aware that he extended his _a priori_ + views on utility to domesticated varieties which are bred for + the slaughter-house. If he now means to indicate that these + appendages are possibly due to natural selection, he is surely + going very far to save his _a priori_ dogma; and in the case + next adduced will have to go further still. + +In the next place, is it either fair or reasonable to expect that a +varietal character of presumably very recent origin should be as +strongly inherited--and therefore as constant both in occurrence and +symmetry--as a true specific character, say, of a thousand times its +age? Even characters of so-called "constant varieties" in a state of +nature are usually less constant than specific characters; while, again, +as Darwin says, "it is notorious that specific characters are more +variable than generic,"--the reason in both cases being, as he proceeds +to show, that the less constant characters are characters of more recent +origin, and therefore less firmly fixed by heredity[100]. Hence I do not +understand how Mr. Wallace can conclude, as he does, "that, admitting +that this peculiar appendage is wholly useless and meaningless, the fact +would be rather an argument against specific characters being also +meaningless, because the latter never have the characteristics [i.e. +inconstancy of occurrence, form, and transmission] which this particular +variation possesses[101]." Mr. Wallace can scarcely suppose that when +specific characters first arise, they present the three-fold kind of +constancy to which he here alludes. But, if not, can it be denied that +these peculiar appendages appear to be passing through a phase of +development which all "specific characters" must have passed through, +before they have had time enough to be firmly fixed by heredity[102]? + + [100] _Origin of Species_, pp. 122-3. + + [101] _Darwinism_, p. 140. + + [102] In the next paragraph Mr. Wallace says that the appendages in + question "are apparently of the same nature as the 'sports' + that arise in our domesticated productions, but which, as Mr. + Darwin says, without the aid of selection would soon + disappear." But I cannot find that Mr. Darwin has made any + such statement: what he does say is, that whether or not a + useless peculiarity will soon disappear without the aid of + selection depends upon the nature of the causes which produce + it. If these causes are of a merely transitory nature, the + peculiarity will also be transitory; but if the causes be + constant, so will be the result. Again, the point to be + noticed about this "sport" is, that, unlike what is usually + understood by a "sport," it affects a whole race or breed, is + transmitted by sexual propagation, and has already attained so + definite a size and structure, that it can only be reasonably + accounted for by supposing the continued operation of _some + constant_ cause. This cause can scarcely be correlation of + growth, since closely similar appendages are often seen in so + different an animal as a goat. Here, also, they run in breeds + or strains, are strongly inherited, and more "constant," as + well as more "symmetrical" than they are in pigs. This, at all + events, is the account I have received of them from + goat-breeders in Switzerland. + +If, however, even this should be denied, what will be said of the second +case, that of the niata cattle? + + "I saw two herds on the northern bank of the Plata.... The forehead + is very short and broad, with the nasal end of the skull, together + with the whole plane of the upper molar-teeth, curved upwards. The + lower jaw projects beyond the upper, and has a corresponding upward + curvature.... The skull which I presented to the College of + Surgeons has been thus described by Professor Owen. 'It is + remarkable from the stunted development of the nasals, + premaxillaries, and fore part of the lower jaw, which is unusually + curved upwards to come into contact with the premaxillaries. The + nasal bones are about one-third the ordinary length, but retain + almost their normal breadth. The triangular vacuity is left between + them and the frontal and lachrymal, which latter bone articulates + with the premaxillary, and thus excludes the maxillary from any + junction with the nasal.' So that even the connexion of some of + the bones is changed. Other differences might be added: thus the + plane of the condyles is somewhat modified, and the terminal edge + of the premaxillaries forms an arch. In fact, on comparison with + the skull of a common ox, scarcely a single bone presents the same + exact shape, and the whole skull has a wonderfully different + appearance[103]." + + [103] Darwin, _Variation_, &c., vol. i. pp. 92-4. + +[Illustration: Fig. 3.--Drawn from nature. R. Coll. Surg. Mus.] + +As I cannot find that this remarkable skull has been figured before, I +have had the accompanying woodcut made in order to compare it with the +skull of a Charsley Forest ox; and a glance is sufficient to show what +"a wonderfully different appearance" it presents. + + * * * * * + +Now the important points in the present connexion with regard to this +peculiar race of cattle are the following. + +Their origin is not known; but it must have been subsequent to the year +1552, when cattle were first introduced to America from Europe, and it +is known that such cattle have been in existence for at least a century. +The breed is very true, and a niata bull and cow invariably produce +niata calves. A niata bull crossed with a common cow, and the reverse +cross, yield offspring having an intermediate character, but with the +niata peculiarities highly conspicuous[104]. + + [104] _Ibid._ p. 94. + +Here, then, we have unquestionable evidence of a whole congeries of very +distinctive characters, so unlike anything that occurs in any other +cattle, that, had they been found in a state of nature, they would have +been regarded as a distinct species. And the highly peculiar characters +which they present conform to all "the most essential features of +specific characters," as these are stated by Mr. Wallace in his +objection to the case of the pig's appendages. That is to say, "they +_are_ symmetrical, they _are_ inherited, and they _are_ constant." In +point of fact, they are _always_ "constant," both as to occurrence and +symmetry, while they are so completely "inherited" that not only does "a +niata bull and cow _invariably_ produce niata calves"; but even when +crossed with other cattle the result is a _hybrid_, "with the niata +character _strongly_ displayed." + +Hence, if we were to follow Mr. Wallace's criteria of specific +characters, which show that the pig's appendages "cannot be classed with +specific characters" (or with anything of the nature of specific +characters), it would follow that the niata peculiarities _can_ be so +classed. This, therefore, is a case where he will find all the reasons +which in other cases he takes to justify him in falling back upon the +argument from ignorance. The cattle are half wild, he may urge; and so +the three-fold constancy of their peculiar characters may very well be +due, either directly or indirectly, to natural selection--i.e. they may +either be of some hidden use themselves, or correlated with some other +modifications that are of use: it is, he may say, as in such cases he +often does say, for us to disprove both these possibilities. + +Well, here we have one of those rare cases where historical information, +or other accidents, admit of our discharging this burden of proving a +negative. Darwin's further description shows that this customary refuge +in the argument from ignorance is most effectually closed. For-- + + "When the pasture is tolerably long, these cattle feed as well as + common cattle with their tongue and palate; but during the great + droughts, when so many animals perish on the Pampas, the niata + breed lies under a great disadvantage, and would, if not attended + to, become extinct; for the common cattle, like horses, are able to + keep alive by browsing with their lips on the twigs of trees and on + reeds; this the niatas cannot so well do, as their lips do not + join, and hence they are found to perish before the common cattle. + This strikes me as a good illustration of how little we are able to + judge from the ordinary habits of an animal, on what circumstances, + occurring only at long intervals of time, its rarity or extinction + may depend. It shows us, also, how natural selection would have + determined the rejection of the niata modification, had it arisen + in a state of nature[105]." + + [105] Darwin, _Variation_, &c. vol. i. p. 94. + +Hence, it is plainly _impossible_ to attribute this modification to +natural selection, either as acting directly on the modified parts +themselves, or indirectly through correlation of growth. And as the +modification is of specific magnitude on the one hand, while it presents +all "the most essential features of specific characters" on the other, I +do not see any means whereby Mr. Wallace can meet it on his _a priori_ +principles. It would be useless to answer that these characters, +although conforming to all his tests of specific characters, differ in +respect of being deleterious, and would therefore lead to extermination +were the animals in a wholly wild state; because, considered as an +argument, this would involve the assumption that, apart from natural +selection, only deleterious characters can arise under nature--i. e. +that merely "indifferent" characters can never do so, which would be +absurd. Indeed, I have chosen this case of the niata cattle expressly +because their strongly marked peculiarities _are_ deleterious, and +therefore exclude Mr. Wallace's appeal to the argument from ignorance of +a possible utility. But if even these pronounced and deleterious +peculiarities can arise and be perpetuated with such constancy and +fidelity, much more is this likely to be the case with less pronounced +and merely neutral peculiarities. + +It may, however, be further objected that these cattle are not +improbably the result of _artificial_ selection. It may be suggested +that the semi-monstrous breed originated in a single congenital +variation, or "sport," which was isolated and multiplied as a curiosity +by the early settlers. But even if such be the explanation of this +particular case, the fact would not weaken our illustration. On the +contrary, it would strengthen our general argument, by showing an +additional means whereby indifferent specific characters can arise and +become fixed in a state of nature. As it seems to me extremely probable +that the niata cattle did originate in a congenital monstrosity, which +was then isolated and multiplied by human agency (as is known to have +been the case with the "ancon sheep"), I will explain why this tends to +strengthen our general argument. + +It is certain that if these animals were ever subject to artificial +isolation for the purpose of establishing their breed, the process must +have ceased a long time ago, seeing that there is no memory or tradition +of its occurrence. Now this proves that, however the breed may have +originated, it has been able to maintain its many and highly peculiar +characters for a number of generations without the help of selection, +either natural or artificial. This is the first point to be clear upon. +Be its origin what it may, we know that this breed has proved capable of +perpetuating itself with uniform "constancy" for a number of generations +after the artificial selection has ceased--supposing such a process ever +to have occurred. And this certain fact that artificial selection, even +if it was originally needed to establish the type, has not been needed +to perpetuate the type, is a full answer to the supposed objection. For, +in view of this fact, it is immaterial what the origin of the niata +breed may have been. In the present connexion, the importance of this +breed consists in its proving the subsequent "stability" of an almost +monstrous form, continued through a long series of generations by the +force of heredity alone, without the aid of any form of selection. + +The next point is, that not only is a seeming objection to the +illustration thus removed, but that, if we do entertain the question of +origin, and if we do suppose the origin of these cattle to have been in +a congenital "sport," afterwards multiplied by artificial isolation, we +actually strengthen our general argument by increasing the importance of +this particular illustration. For the illustration then becomes +available to show how indifferent specific characters may sometimes +originate in merely individual sports, which, if not immediately +extinguished by free intercrossing, will perpetuate themselves by the +unaided force of heredity. But this is a point to which we shall recur +in the ensuing chapter. + +In conclusion, it is worth while to remark, with regard to Mr. Wallace's +argument from constancy, that, as a matter of fact, utility does not +seem to present any greater power in securing "stability of characters" +than any other cause of like constancy. Thus, for instance, whatever the +causes may have been which have produced and perpetuated the niata breed +of cattle, they have certainly produced a wonderful "stability" of a +great modification in a wonderfully short time. And the same has to be +said of the ducks in St. James' Park, as well as sundry other cases. On +the other hand, when, as in the case of numberless natural species, +modification has been undoubtedly produced by natural selection, +although the modification must have had a very much longer time in which +to have been fixed by heredity, it is often far from being +stable--notwithstanding that Mr. Wallace regards stability as a +criterion of specific characters. Indeed--and this is more suggestive +still--there even seems to be a kind of _inverse_ proportion between the +utility and the stability of a specific character. The explanation +appears to be (_Origin of Species_, pp. 120-2), that the more a specific +character has been forced on by natural selection on account of its +utility, the less time will it have had to become well fixed by heredity +before attaining a full development. Moreover, as Darwin adds, in cases +where the modification has not only been thus "comparatively recent," +but also "extraordinarily great," the probability is that the parts so +modified must have been very variable in the first instance, and so are +all the more difficult to render constant by heredity. Thus we see that +utility is no better--even if it be so good--a cause of stability in +specific characters, as are the unknown causes of stability in many +varietal characters[106]. + + [106] Should it be objected that useless characters, according to my + own view of the Cessation of Selection, ought to disappear, + and therefore cannot be constant, the answer is evident. For, + by hypothesis, it is only those useless characters which were + at one time useful that disappear under this principle. + Selection cannot cease unless it was previously present--i.e. + save in cases where the now useless character was originally + due to selection. Hence, in all cases where it was due to any + other cause, the useless character will persist at least as + long as its originating cause continues to operate. And even + after the latter (whatever it may be) has ceased to operate, + the useless character will but slowly degenerate, until the + eventual failure of heredity causes it to disappear _in + toto_--long before which time it may very well have become a + genetic, or some higher, character. + + + + +CHAPTER VIII. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_continued_). + + +Let us now proceed to indicate some of the causes, other than natural +selection, which may be regarded as adequate to induce such changes in +organic types as are taken by systematists to constitute diagnostic +distinctions between species and species. We will first consider causes +external to organisms, and will then go on to consider those which occur +within the organisms themselves: following, in fact, the classification +which Darwin has himself laid down. For he constantly speaks of such +causes as arising on the one hand, from "changed conditions of life" +and, on the other hand, from "the nature of the organism"--that is, from +internal processes leading to "variations which seem to us in our +ignorance to arise spontaneously." + +In neither case will it be practicable to give more than a brief +_resume_ of all that might be said on these interesting topics. + + +I. _Climate._ + +There is an overwhelming mass of evidence to prove that the assemblage +of external conditions of life conveniently summarized in the word +Climate, exercise a potent, an uniform, and a permanent influence on +specific characters. + +With regard to plants, Darwin adduces a number of facts to show the +effects of climate on wheat, cabbages, and other vegetables. Here, for +example, is what he says with regard to maize imported from America to +Germany:-- + + "During the first year the plants were twelve feet high, and a few + seeds were perfected; the lower seeds in the ear kept true to their + proper form, but the upper seeds became slightly changed. In the + second generation the plants were from nine to ten feet high, and + ripened their seed better; the depression on the outer side of the + seed had almost disappeared, and the original beautiful white + colour had become duskier. Some of the seeds had even become + yellow, and in their now rounded form they approached the common + European maize. In the third generation nearly all resemblance to + the original and very distinct American parent-form was lost[107]." + + [107] _Variation_, &c. vol. i. p. 340. + +As these "highly remarkable" changes were effected in but three +generations, it is obvious that they cannot have been dependent on +selection of any kind. The same remark applies to trees. Thus,-- + + "Mr. Meehan has compared twenty-nine kinds of American trees with + their nearest European allies, all grown in close proximity and + under as nearly as possible the same conditions. In the American + species he finds, with the rarest exceptions, that the leaves fall + earlier in the season, and assume before their fall a brighter + tint; that they are less deeply toothed or serrated; that the buds + are smaller; that the trees are more diffuse in growth and have + fewer branchlets; and, lastly, that the seeds are smaller--all in + comparison with the corresponding European species. Now, + considering that these corresponding trees belong to several + distinct orders, and that they are adapted to widely different + stations, it can hardly be supposed that their differences are of + any special service to them in the New and Old worlds; and, if so, + such differences cannot have been gained through natural selection, + and must be attributed to the long continued action of a different + climate[108]." + + [108] _Variation_, &c. vol. ii. p. 271. + +These cases, however, I quote mainly in order to show Darwin's opinion +upon the matter, with reference to the absence of natural selection. +For, where the vegetable kingdom is concerned, the fact of climatic +variation is so general, and in its relation to diagnostic work so +important, that it constitutes one of the chief difficulties against +which species-makers have to contend. And the more carefully the subject +is examined the greater does the difficulty become. But, as to this and +other general facts, it will be best to allow a recognized authority to +speak; and therefore I will give a few extracts from Kerner's work on +_Gute und schlechte Arten_. + +He begins by showing that geographical (or it may be topographical) +varieties of species are often so divergent, that without a knowledge of +intermediate forms there could be no question as to their being good +species. As a result of his own researches on the subject, he can +scarcely find language strong enough to express his estimate of the +extent and the generality of this source of error. In different parts of +Europe, or even in different parts of the Alps, he has found these +climatic varieties in such multitudes and in such high degrees both of +constancy and divergence, that, after detailing his results, he +finishes his essay with the following remarkable conclusions:-- + + "Die Wissenchaft geht aber ihren Entwicklungsgang im grossen Ganzen + gerade so, wie die Erkenntniss bei jedem einzelnen Naturforscher. + Fast jeder Botaniker muss seinen Entwicklungsgang durchmachen und + gelangt endlich mehr oder weniger nahe zu demselben Ziele. Die + Ungleichheit besteht nur darin, dass der eine langsamer, der andere + aber rascher bei dem Ziele ankommt. Anfaenglich mueht sich jeder ab, + die Formen in hergebrachter Weise zu gliedern und die 'guten Arten' + herauszulesen. Mit der Erweiterung des Gesichtskreises und mit der + Vermehrung der Anschauungen aber schwindet auch immer mehr der + Boden unter den Fuessen, die bisher fuer unverrueckbar gehaltenen + Grenzen der gut geglaubten Arten stellen sich als eine der Natur + angelegte Zwangsjacke heraus, die Uebcrzeugung, dass die Grenzen, + welche wir ziehen, eben nur kuenstliche sind, gewinnt immer mehr und + mehr die Oberhand, und wer nicht gerade zu den hartgesottenen + Eigensinnigen gehoert, und wer die Wahrheit hoeher stellt als das + starre Festhalten an seinen frueheren Ansichten, geht schliesslich + bewusst oder unbewusst in das Lager derjenigen ueber, in welchem + auch ich mir ein bescheidenes Plaetzchen aufgesucht habe." + +By these "hard-boiled" botanists he means those who entertain the +traditional notion of a species as an assemblage of definite +characters, always and everywhere associated together. This notion +(Artsbestaendigkeit) must be entirely abandoned. Summarizing Kerner's +facts for their general results we find that his extensive +investigations have proved that in his numberless kinds of European +plants the following relations frequently obtain. Supposing that there +are two or more allied species, A and B, then A' and B' may be taken to +represent their respective types as found in some particular area. It +does not signify whether A' and B' are geographically remote from, or +close to, A and B; the point is that, whether in respect of temperature, +altitude, moisture, character of soil, &c., there is some difference in +the conditions of life experienced by the plants growing at the +different places. Now, in numberless plants it is found that the typical +or constant peculiarities of A' differ more from those of A than they do +from those of B; while, conversely, the characters of A' may bear more +resemblance to those of B' than they do to those of A--on account of +such characters being due to the same external causes in both cases. The +consequence is that A' might more correctly be classified with B', or +_vice versa_. Another consequence is that whether A and B, or A' and B', +be recorded as the "good species" usually depends upon which has +happened to have been first described. + +Such a mere abstract of Kerner's general results, however, can give no +adequate idea of their cogency: for this arises from the number of +species in which specific characters are thus found to change, and even +to _interchange_, with different conditions of life. Thus he gives an +amusing parable of an ardent young botanist, Simplicius, who starts on a +tour in the Tyrol with the works of the most authoritative systematists +to assist him in his study of the flora. The result is that Simplicius +becomes so hopelessly bewildered in his attempts at squaring their +diagnostic descriptions with the facts of nature, that he can only +exclaim in despair--"Sonderbare Flora, diese tirolische, in welcher so +viele characteristische Pflanzen nur schlechte Arten, oder gar noch +schlechter als schlechte Arten, sind." Now, in giving illustrations of +this young man's troubles, Kerner fills five or six pages with little +else than rows of specific names. + +Upon the whole, Kerner concludes that the more the subject is studied, +the more convinced must the student become that all distinction between +species as "good" and "bad" vanishes. In other words, the more that our +knowledge of species and of their diagnostic characters increases, the +more do we find that "bad species" multiply at the expense of "good +species"; so that eventually we must relinquish the idea of "good +species" altogether. Or, conversely stated, we must agree to regard as +equally "good species" any and every assemblage of individuals which +present the same peculiarities: provided that these peculiarities do not +rise to a generic value, they equally deserve to be regarded as +"specific characters," no matter how trivial, or how local, they may be. +In fact, he goes so far as to say that when, as a result of experiments +in transplantation from one set of physical conditions to another, +seedlings are found to present any considerable and constant change in +their specific characters, these seedlings are no less entitled to be +regarded as a "good species" than are the plants from which they have +been derived. Probably few systematists will consent to go quite so far +as this; but the fact that Kerner has been led deliberately to propound +such a statement as a result of his wide observations and experiments is +about as good evidence as possible on the points with which we are here +concerned. For even Simplicius would hardly be quite so simple as to +suppose that each one of all the characters which he observes in his +"remarkable flora," so largely composed of "bad or even worse than bad +species," is of utilitarian significance. + +Be it noted, however, that I am not now expressing my own opinion. There +are weighty reasons against thus identifying climatic variations with +good species--reasons which will be dealt with in the next chapter. +Kerner does not seem to appreciate the weight of these reasons, and +therefore I do not call him as a witness to the subject as a whole; but +only to that part of it which has to do with the great and general +importance of climatic variability in relation to diagnostic work. And +thus far his testimony is fully corroborated by every other botanist who +has ever attended to the subject. Therefore it does not seem worth while +to quote further authorities in substantiation of this point, such as +Gaertner, De Candolle, Naegeli, Peter, Jordan, &c. For nowadays no one +will dispute the high generality and the frequently great extent of +climatic variation where the vegetable kingdom is concerned. Indeed, it +may fairly be doubted whether there is any one species of plant, whose +distribution exposes it to any considerable differences in its external +conditions of life, which does not present more or less considerable +differences as to its characters in different parts of its range. The +principal causes of such climatic variation appear to be the chemical, +and, still more, the mechanical nature of soil; temperature; intensity +and diurnal duration of light in spring and summer; moisture; presence +of certain salts in the air and soil of marine plants, or of plants +growing near mineral springs; and sundry other circumstances of a more +or less unknown character. + +Before closing these remarks on climatic variation in the vegetable +kingdom, prominent attention must be directed to a fact of broad +generality and, in relation to our present subject, of considerable +importance. This is that the same external causes very frequently +produce the same effects in the way of specific change throughout large +numbers of _unrelated_ species--i.e. species belonging to different +genera, families, and orders. Moreover, throughout all these unrelated +species, we can frequently trace a uniform correlation between the +degrees of change and the degrees to which they have been subjected to +the causes in question. + +As examples, all botanists who have attended to the subject are struck +by the similarity of variation presented by different species growing on +the same soils, altitudes, latitudes, longitudes, and so forth. Plants +growing on chalky soils, when compared with those growing on richer +soils, are often more thickly covered with down, which is usually of a +white or grey colour. Their leaves are frequently of a bluish-green +tint, more deeply cut, and less veined, while their flowers tend to be +larger and of a lighter tint. There are similarly constant differences +in other respects in varieties growing on sundry other kinds of soils. +Sea-salt has the general effect, on many different kinds of plants, of +producing moist fleshy leaves, and red tints. Experiments in +transplantation have shown that these changes may be induced +artificially; so there can be no doubt as to its being this that and the +other set of external conditions which produces them in nature. Again, +dampness causes leaves to become smoother, greener, less cut, and the +flowers to become darker; while dryness tends to produce opposite +effects. I need not go on to specify the particular results on all kinds +of plants of altitude, latitude, longitude, and so forth. For we are +concerned only with the fact that these two correlations may be regarded +as general laws appertaining to the vegetable kingdom--namely, (A) that +the same external causes produce similar varietal effects in numerous +unallied species of plants; and, (B) that the more these species are +exposed to such causes the greater is the amount of varietal effect +produced--so that, for instance, on travelling from latitude to +latitude, longitude to longitude, altitude to altitude, &c., we may see +greater and greater degrees of such definite and more or less common +varietal changes affecting the unallied species in question. Now these +general laws are of importance for us, because they prove unequivocally +that it is the direct action of external conditions of life which +produce climatic variations of specific types. And, taken in connexion +with the results of experiments in transplantation (which in a single +generation may yield variations similar to those found in nature under +similar circumstances), these general laws still further indicate that +climatic variations are "indifferent" variations. In other words, we +find that changes of specific characters are of widespread occurrence in +the vegetable kingdom, that they are constantly and even proportionally +related to definite external circumstances, but yet that, in as far as +they are climatic, they cannot be attributed to the agency of natural +selection[109]. + + [109] Since the above paragraphs have been in type, the Rev. G. + Henslow has published his Linnaean Society papers which are + mentioned in the introductory chapter, and which deal in more + detail with this subject, especially as regards the facies of + desert floras. + +Turning next to animals, it may first be observed that climatic +conditions do not appear to exercise an influence either so general or +so considerable as in the case of plants. Nevertheless, although these +influences are relatively more effective in the vegetable kingdom than +they are in the animal, absolutely considered they are of high +generality and great importance even in the latter. But as this fact is +so well recognized by all zoologists, it will be needless to give more +than a very few illustrations. Indeed, throughout this discussion on +climatic influences my aim is merely to give the general reader some +idea of their importance in regard to systematic natural history; and, +therefore, such particular cases as are mentioned are selected only as +samples of whole groups of cases more or less similar. + +With regard to animals, then, we may best begin by noticing that, just +as in the case of plants, there is good evidence of the same external +causes producing the same effects in multitudes of species belonging to +different genera, families, orders, and even classes. Moreover, we are +not without similarly good evidence of _degrees_ of specific change +taking place in correlation with _degrees_ of climatic change, so that +we may frequently trace a gradual progress of the former as we advance, +say, from one part of a large continent to another. Instances of these +correlations are not indeed so numerous in the animal kingdom as they +are in the vegetable. Nevertheless they are amply sufficient for our +present purposes. + +For example, Mr. Allen has studied in detail changes of size and colour +among birds and mammals on the American continent; and he finds a +wonderfully close sliding scale of both, corresponding stage by stage +with gradual changes of climate. Very reasonably he attributes this to +the direct influence of climatic conditions, without reference to +natural selection--as does also Mr. Gould with reference to similar +facts which he has observed among the birds of Australia. Against this +view Mr. Wallace urges, "that the effects are due to the greater or less +need of protection." But it is difficult to believe that such can be the +case where so innumerable a multitude of widely different species are +concerned--presenting so many diverse habits, as well as so many +distinct habitats. Moreover, the explanation seems incompatible with the +_graduated_ nature of the change, and also with the fact that not only +colouration but size, is implicated. + +We meet with analogous facts in butterflies. Thus _Lycaena agestis_ not +only presents seasonal variations, (A) and (B); but while (A) and (B) +are respectively the winter and summer forms in Germany, (B) and (C) are +the corresponding forms in Italy. Therefore, (B) is in Germany the +summer form, and in Italy the winter form--the German winter form (A) +being absent in Italy, while the Italian summer form (C) is absent in +Germany. Probably these facts are due to differences of temperature in +the two countries, for experiments have shown that when pupae of sundry +species of moths and butterflies are exposed to different degrees of +temperature, the most wonderful changes of colour may result in the +insects which emerge. The remarkable experiments of Dorfmeister and +Weismann in relation to this subject are well known. More recently Mr. +Merrifield has added to their facts, and concludes that the action of +cold upon the pupae--and also, apparently, upon the larvae--has a +tendency to produce dark hues in the perfect insect[110]. + + [110] _Trans. Entom. Soc._ 1889, part i. p. 79 _et seq._ + +But, passing now from such facts of climatic variations over wide areas +to similar facts within small areas, in an important _Memoir on the Cave +Fauna of North America_, published a few years ago by the American +Academy of Sciences, it is stated:-- + + "As regards change of colour, we do not recall an exception to the + general rule that all cave animals are either colourless or nearly + white, or, as in the case of Arachnida and Insects, much paler than + their out-of-door relatives." + +Now, when we remember that these cave faunas comprise representatives of +nearly all classes of the animal kingdom, it becomes difficult, if not +impossible, to imagine that so universal a discharge of colouring can be +due to natural selection. It must be admitted that the only way in which +natural selection could act in this case would be indirectly through the +principle of correlation. There being no light in the caves, it can be +of no advantage to the animals concerned that they should lose their +colour for the sake of protection, or for any other reason of a +similarly direct kind. Therefore, if the loss of colour is to be +ascribed to natural selection, this can only be done by supposing that +natural selection has here acted indirectly through the principle of +correlation. There is evidence to show that elsewhere modification or +loss of colour is in some cases brought about by natural selection, on +account of the original colour being correlated with certain +physiological characters (such as liability to particular diseases, +&c.); so that when natural selection operates directly upon these +physiological characters, it thereby also operates indirectly upon the +correlated colours. But to suppose that this can be the explanation of +the uniform diminution of colour in all inhabitants of dark caves would +be manifestly absurd. If there were only one class of animals in these +caves, such as Insects, it might be possible to surmise that their +change of colour is due to natural selection acting directly upon their +physiological constitutions, and so indirectly upon their colours. But +it would be absurd to suppose that such can be the explanation of the +facts, when these extend in so similar a manner over so many scores of +species belonging to such different types of animal life. + +With more plausibility it might be held that the universal discharge of +colour in these cave-faunas is due, not to the presence, but to the +absence of selection--i. e. to the cessation of selection, or panmixia. +But against this--at all events as a full or general explanation--lie +the following facts. First, in the case of Proteus--which has often been +kept for the purposes of exhibition &c., in tanks--the skin becomes dark +when the animal is removed from the cave and kept in the light. +Secondly, deep-sea faunas, though as much exposed as the cave-faunas, to +the condition of darkness, are not by any means invariably colourless. +On the contrary, they frequently present brilliant colouration. Thus it +is evident that if panmixia be suggested in explanation of the +discharge of colouring in cave-faunas, the continuance of colour in +deep-sea faunas appears to show the explanation insufficient. Thirdly, +according to my view of the action of panmixia as previously explained, +no _total_ discharge of colouration is likely to be caused by such +action alone. At most the bleaching as a result of the mere withdrawal +of selection would proceed only to some comparatively small extent. +Fourthly, Mr. Packard in the elaborate _Memoir on Cave Fauna_, already +alluded to, states that in some of the cases the phenomena of bleaching +appear to have been induced within very recent times--if not, indeed, +within the limits of a single generation. Should the evidence in support +of this opinion prove trustworthy, of course in itself it disposes of +any suggestion either of the presence or the absence of natural +selection as concerned in the process. + +Nevertheless, I myself think it inevitable that to some extent the +cessation of selection must have helped in discharging the colour of +cave faunas; although for the reasons now given it appears to me that +the main causes of change must have been of that direct order which we +understand by the term climatic. + +As regards dogs, the Rev. E. Everest found it impossible to breed Scotch +setters in India true to their type. Even in the second generation no +single young dog resembled its parents either in form or shape. "Their +nostrils were more contracted, their noses more pointed, their size +inferior, and their limbs more slender[111]." Similarly on the coast of +New Guinea, Bosman says that imported breeds of dogs "alter strangely; +their ears grow long and stiff like those of foxes, to which colour they +also incline ... and in three or four broods their barking turns into a +howl[112]." + + [111] _Variation_, &c. vol. i. p. 40. + + [112] _Variation_, &c. vol. i. p. 40. + +Darwin gives numerous facts showing the effects of climate on horses, +cattle, and sheep, in altering, more or less considerably, the +characters of their ancestral stocks. He also gives the following +remarkable case with regard to the rabbit. Early in the fifteenth +century a common rabbit and her young ones were turned out on the island +of Porto Santo, near Madeira. The feral progeny now differ in many +respects from their parent stock. They are only about one-third of the +weight, present many differences in the relative sizes of different +parts, and have greatly changed in colour. In particular, the black on +the upper surface of the tail and tips of the ears, which is so constant +in all other wild rabbits of the world as to be given in most works as a +specific character, has entirely disappeared. Again, "the throat and +certain parts of the under surface, instead of being pure white, are +generally grey or leaden colour," while the upper surface of the whole +body is redder than in the common rabbit. Now, what answer have our +opponents to make to such a case as this? Presumably they will answer +that the case simply proves the action of natural selection during the +best part of 400 years on an isolated section of a species. Although we +cannot say of what use all these changes have been to the rabbits +presenting them, nevertheless we _must_ believe that they have been +produced by natural selection, and therefore _must_ present some hidden +use to the isolated colony of rabbits thus peculiarly situated. Four +centuries is long enough to admit of natural selection effecting all +these changes in the case of so rapidly breeding an animal as the +rabbit, and therefore it is needless to look further for any explanation +of the facts. Such, I say, is presumably the answer that would be given +by the upholders of natural selection as the only possible cause of +specific change. But now, in this particular case it so happens that the +answer admits of being conclusively negatived, by showing that the great +assumption on which it reposes is demonstrably false. For Darwin +examined two living specimens of these rabbits which had recently been +sent from Porto Santo to the Zoological Gardens, and found them coloured +as just described. Four years afterwards the dead body of one of them +was sent to him, and then he found that the following changes had taken +place. "The ears were plainly edged, and the upper surface of the tail +was covered with blackish-grey fur, and the whole body was much less +red; so that under the English climate this individual rabbit has +recovered the proper colour of its fur in rather less than four years!" + +Mr. Darwin adds:-- + + "If the history of these Porto Santo rabbits had not been known, + most naturalists, on observing their much reduced size, their + colour, reddish above and grey beneath, their tails and ears not + tipped with black, would have ranked them as a distinct species. + They would have been strongly confirmed in this view by seeing them + alive in the Zoological Gardens, and hearing that they refused to + couple with other rabbits. Yet this rabbit, which there can be + little doubt would thus have been ranked as a distinct species, as + certainly originated since the year 1420[113]." + + [113] _Variation_, &c. vol. i. p. 120. + +Moreover, it certainly originated as a direct result of climatic +influences, independent of natural selection; seeing that, as soon as +individual members of this apparently new species were restored to their +original climate, they recovered their original colouration. + +As previously remarked, it is, from the nature of the case, an +exceedingly difficult thing to prove in any given instance that natural +selection has not been the cause of specific change, and so finally to +disprove the assumption that it must have been. Here, however, on +account of historical information, we have a crucial test of the +validity of this assumption, just as we had in the case of the niata +cattle; and, just as in their case, the result is definitely and +conclusively to overturn the assumption. If these changes in the Porto +Santo rabbits had been due to the gradual influence of natural selection +guided by inscrutable utility, it is simply impossible that the same +individual animals, in the course of their own individual life-times, +should revert to the specific characters of their ancestral stock on +being returned to the conditions of their ancestral climate. Therefore, +unless any naturalist is prepared to contradict Darwin's statement that +the changes in question amount to changes of specific magnitude, he can +find no escape from the conclusion that distinctions of specific +importance may be brought about by changes of habitat alone, without +reference to utility, and therefore independently of natural selection. + + +II. _Food._ + +Although, as yet, little is definitely known on the subject, there can +be no doubt that in the case of many animals differences of food induce +differences of colour within the life-time of individuals, and therefore +independently of natural selection. + +Thus, sundry definite varieties of the butterfly _Euprepia caja_ can be +reared according to the different nourishment which is supplied to the +caterpillar; and other butterflies are also known on whose colouring and +markings the food of the caterpillar has great influence[114]. + + [114] See especially, Koch, _Die Raupen und Schmetterling der + Wetterau_, and _Die Schmetterling des Suedwestlichen + Deutschlands_, whose very remarkable results of numerous and + varied experiments are epitomized by Eimer, _Organic + Evolution_, Eng. Trans. pp. 147-153; also Poulton, _Trans. + Entom. Soc._ 1893. + +Again, I may mention the remarkable case communicated to Darwin by +Moritz Wagner, of a species of _Saturnia_, some pupae of which were +transported from Texas to Switzerland in 1870. The moths which emerged +in the following year were like the normal type in Texas. Their young +were supplied with leaves of _Juglans regia_, instead of their natural +food, _J. nigra_; and the moths into which these caterpillars changed +were so different from their parents, both in form and colour, "that +they were reckoned by entomologists as a distinct species[115]." + + [115] Mivart, _On Truth_, p. 378. + +With regard to mollusks, M. Costa tells us that English oysters, when +turned down in the Mediterranean, "_rapidly_ became like the true +Mediterranean oyster, altered their manner of growth, and formed +prominent diverging rays." This is most probably due to some change of +food. So likewise may be the even more remarkable case of _Helix +nemoralis_, which was introduced from Europe to Virginia a few years +ago. Under the new conditions it varied to such an extent that up to +last year no less than 125 varieties had been discovered. Of these 67, +or more than half, are new--that is, unknown in the native continent of +the species[116]. + + [116] Cockerell, _Nature_, vol. xli. p. 393. + +In the case of Birds, the Brazilian parrot _Chrysotis festiva_ changes +the green in its feathers to red or yellow, if fed on the fat of certain +fishes; and the Indian Lori has its splendid colouring preserved by a +peculiar kind of food (Wallace). The Bullfinch is well known to turn +black when fed on hemp seeds, and the Canary to become red when fed on +cayenne pepper (Darwin). Starting from these facts, Dr. Sauermann has +recently investigated the subject experimentally; and finds that not +only finches, but likewise other birds, such as fowls, and pigeons, are +subject to similar variations of colour when fed on cayenne pepper; but +in all cases the effect is produced only if the pepper is given to the +young birds before their first moult. Moreover, he finds that a moist +atmosphere facilitates the change of colour, and that the ruddy hue is +discharged under the influence either of sunlight or of cold. Lastly, he +has observed that sundry other materials such as glycerine and aniline +dyes, produce the same results; so there can be no doubt that organic +compounds probably occur in nature which are capable of directly +affecting the colours of plumage when eaten by birds. Therefore the +presence of such materials in the food-stuffs of birds occupying +different areas may very well in many cases determine differences of +colouration, which are constant or stable so long as the conditions of +their production are maintained. + + +III. _Sexual Selection._ + +Passing on now to causes of specific change which are internal, or +comprised within the organisms themselves, we may first consider the +case of Sexual Selection. + +Mr. Wallace rejects the theory of sexual selection _in toto_, and +therefore nothing that can be said under this head would be held by him +to be relevant. Many naturalists, however, believe that Darwin was right +in the large generalization which he published under this title; and in +so far as any one holds that sexual selection is a true cause of +specific modification, he is obliged to believe that innumerable +specific characters--especially in birds and mammals--have been produced +without reference to utility (other, of course, than utility for sexual +purposes), and therefore without reference to natural selection. This is +so obvious that I need not pause to dilate upon it. One remark, however, +may be useful. Mr. Wallace is able to make a much more effective use of +his argument from "necessary instability" when he brings it against the +Darwinian doctrine of sexual selection, than he does when he brings it +against the equally Darwinian doctrine of specific characters in general +not being all necessarily due to natural selection. In the latter case, +it will be remembered, he is easily met by showing that the causes of +specific change other than natural selection, such as food, climate, +&c., may be quite as general, persistent, and uniform, as natural +selection itself; and therefore in this connexion Mr. Wallace's argument +falls to the ground. But the argument is much more formidable as he +brings it to bear against the theory of sexual selection. Here he asks, +What is there to guarantee the uniformity and the constancy of feminine +taste with regard to small matters of embellishment through thousands of +generations, and among animals living on extensive areas? And, as we +have seen in Part 1, it is not easy to supply an answer. Therefore this +argument from the "necessary instability of character" is of +immeasurably greater force as thus applied against Darwin's doctrine of +sexual selection, than it is when brought against his doctrine that all +specific characters need not necessarily be due to natural selection. +Therefore, also, if any one feels disposed to attach the smallest degree +of value to this argument in the latter case, consistency will require +him to allow that in the former case it is simply overwhelming, or in +itself destructive of the whole theory of sexual selection. And, +conversely, if his belief in the theory of sexual selection can survive +collision with this objection from instability, he ought not to feel any +tremor of contact when the objection is brought to bear against his +scepticism regarding the alleged utility of all specific characters. For +assuredly no specific character which is apparent to our eyes can be +supposed to be so refined and complex (and therefore so presumably +inconstant and unstable), as are those minute changes of cerebral +structure on which a psychological preference for all the refined +shadings and many pigments of a complicated pattern must be held +ultimately to depend. For this reason, then, as well as for those +previously adduced, if any one agrees with Darwin in holding to the +theory of sexual selection notwithstanding this objection from the +necessary instability of unuseful embellishments, _a fortiori_ he ought +to disregard the objection altogether in its relation to useless +specific characters of other kinds. + +But quite apart from this consideration, which Mr. Wallace and his +followers may very properly say does not apply to them, let us see what +they themselves have made of the facts of secondary sexual +characters--which, of course, are for the most part specific +characters--in relation to the doctrine of utility. + +Mr. Wallace himself, in his last work, quotes approvingly a letter which +he received in 1869 from the Rev. O Pickard-Cambridge, as follows:-- + + "I myself doubt that particular application of the Darwinian theory + which attributes male peculiarities of form, structure, colour, and + ornament to female appetency or predilection. There is, it seems to + me, undoubtedly something in the male organization of a special and + sexual nature, which, of its own vital force, develops the + remarkable male peculiarities so commonly seen, _and of no + imaginable use to that sex_. In as far as these peculiarities show + a great vital power, they point out to us the finest and strongest + individuals of the sex, and show us which of them would most + certainly appropriate to themselves the best and greatest number of + females, and leave behind them the strongest and greatest number of + progeny. And here would come in, as it appears to me, the proper + application of Darwin's theory of Natural Selection; _for the + possessors of greatest vital power being those most frequently + produced and reproduced, the external signs of it would go on + developing in an ever increasing exaggeration_, only to be checked + where it became really detrimental in some respect or other to the + individual[117]." + + [117] _Darwinism_, pp.[typo: period missing in scan] 296-7: italics + mine. + +Here then the idea is, as more fully expressed by Mr. Wallace in the +context, that all the innumerable, frequently considerable, and +generally elaborate "peculiarities of form, structure, colour, and +ornament," which Darwin attributed to sexual selection, are really due +to "the laws of growth." Diverse, definite, and constant though these +specific peculiarities be, they are all but the accidental or +adventitious accompaniments of "vigour," or "vital power," due to +natural selection. Now, without waiting to dispute this view, which has +already been dealt with in the chapter on Sexual Selection in Part I, it +necessarily follows that "a large proportional number of specific +characters," which, while presenting "no imaginable use," are very much +less remarkable, less considerable, less elaborate, &c., must likewise +be due to this "correlation with vital power." But if the principle of +correlation is to be extended in this vague and general manner, it +appears to me that the difference between Mr. Wallace and myself, with +respect to the principle of utility, is abolished. For of course no one +will dispute that the prime condition to the occurrence of "specific +characters," whether useful or useless, is the existence of some form +which has been denominated a "species" to present them; and this is +merely another way of saying that such characters cannot arise except in +correlation with a general fitness due to natural selection. Or, to put +the case in Mr. Wallace's own words--"This development [of useless +specific characters] will necessarily proceed by the agency of natural +selection [as a necessary condition] _and the general laws which +determine the production of colour and of ornamental appendages_." The +case, therefore, is just the same as if one were to say, for example, +that all the ailments of animals and plants proceed from correlation +with life (as a necessary condition), "and the general laws which +determine the production" of ill-health, or of specific disease. In +short, the word "correlation" is here used in a totally different sense +from that in which it is used by Darwin, and in which it is elsewhere +used by Wallace for the purpose of sustaining his doctrine of specific +characters as necessarily useful. To say that a useless character A is +correlated with a useful one B, is a very different thing from saying +that A is "correlated with vital power," or with the general conditions +to the existence of the species to which it belongs. So far as the +present discussion is concerned, no exception need be taken to the +latter statement. For it simply surrenders the doctrine against which I +am contending. + + +IV. _Isolation._ + +It is the opinion of many naturalists who are well entitled to have an +opinion upon the subject, that, in the words of Mr. Dixon, "Isolation +can preserve a non-beneficial as effectually as natural selection can +preserve a beneficial variation[118]." The ground on which this doctrine +rests is thus clearly set forth by Mr. Gulick:--"The fundamental cause +of this seems to lie in the fact that no two portions of a species +possess exactly the same average characters; and, therefore, that the +initial differences are for ever reacting on the environment and on each +other in such a way as to ensure increasing divergence in each +generation, as long as the individuals of the two groups are kept from +intergenerating[119]." In other words, as soon as a portion of a species +is separated from the rest of that species, so that breeding between the +two portions is no longer possible, the general average of characters in +the separated portion not being in all respects precisely the same as it +is in the other portion, the result of in-breeding among all individuals +of the separated portion will eventually be different from that which +obtains in the other portion; so that, after a number of generations, +the separated portion may become a distinct species from the effect of +isolation alone. Even without the aid of isolation, any original +difference of average characters may become, as it were, magnified in +successive generations, provided that the divergence is not harmful to +the individuals presenting it, and that it occurs in a sufficient +proportional number of individuals not to be immediately swamped by +intercrossing. For, as Mr. Murphy has pointed out, in accordance with +Delboeuf's law, "if, in any species, a number of individuals, bearing a +ratio not infinitely small to the entire number of births, are in every +generation born with a particular variation which is neither beneficial +nor injurious, and if it be not counteracted by reversion, then the +proportion of the new variety to the original form will increase till it +approaches indefinitely near to equality[120]." Now even Mr. Wallace +himself allows that this must be the case; and thinks that in these +considerations we may find an explanation of the existence of certain +definite varieties, such as the melanic form of the jaguar, the brindled +or ring-eyed guillemot, &c. But, on the other hand, he thinks that such +varieties must always be unstable, and continually produced in varying +proportions from the parent forms. We need not, however, wait to dispute +this arbitrary assumption, because we can see that it fails, even as an +assumption, in all cases where the superadded influence of isolation is +concerned. Here there is nothing to intercept the original tendency to +divergent evolution, which arises directly out of the initially +different average of qualities presented by the isolated section of the +species, as compared with the rest of that species[121]. + + [118] _Nature_, vol. xxxiii. p. 100. + + [119] _Divergent Evolution through Cumulative Segregation_, Linn. + Journ. Zoology, vol. xx. p. 215. + + [120] _Habit and Intelligence_, p. 241. + + [121] Allusion may here again be made to the case of the niata + cattle. For here is a case where a very extreme variety is + certainly not unstable, nor produced in varying proportions + from the parent form. Moreover, as we have seen in the + preceding chapter, this almost monstrous variety most probably + originated as an individual sport--being afterwards maintained + and multiplied for a time by artificial selection. Now, + whether or not this was the case, we can very well see that it + may have been. Hence it will serve to illustrate another + possibility touching the origin and maintenance of useless + specific characters. For what is to prevent an individual + congenital variation of any kind (provided it be not harmful) + from perpetuating itself as a "varietal," and eventually, + should offspring become sufficiently numerous, a "specific + character"? There is nothing to prevent this, save panmixia, + or the presence of free intercrossing. But, as we shall see in + the next division of this treatise, there are in nature many + forms of isolation. Hence, as often as a small number of + individuals may have experienced isolation in any of its + forms, opportunity for perpetuation will have been given to + any congenital variations which may happen to arise. Should + any of these be pronounced variations, it would afterwards be + ranked as a specific character. I do not myself think that + this is the way in which indifferent specific characters + _usually_ originate. On the contrary, I believe that their + origin is most frequently due to the influence of isolation on + the average characters of the whole population, as briefly + stated in the text. But here it seems worth while to notice + this possibility of their occasionally arising as merely + individual variations, afterwards perpetuated by any of the + numerous isolating conditions which occur in nature. For, if + this can be the case with a varietal form so extreme as to + border on the monstrous, much more can it be so with such + minute differences as frequently go to constitute specific + distinctions. It is the business of species-makers to search + out such distinctions, no matter how trivial, and to record + them as "specific characters." Consequently, wherever in + nature a congenital variation happens to arise, and to be + perpetuated by the force of heredity alone under any of the + numerous forms of isolation which occur in nature, there will + be a case analogous to that of the niata cattle. + +As we shall have to consider the important principle of isolation more +fully on a subsequent occasion, I need not deal with it in the present +connexion, further than to remark that in this principle we have what +appears to me a full and adequate condition to the rise and continuance +of specific characters which need not necessarily be adaptive +characters. And, when we come to consider the facts of isolation more +closely, we shall find superabundant evidence of this having actually +been the case. + + +V. _Laws of Growth._ + +Under this general term Darwin included the operation of all unknown +causes internal to organisms leading to modifications of form or +structure--such modifications, therefore, appearing to arise, as he says +"spontaneously," or without reference to utility. That he attributed no +small importance to the operation of these principles is evident from +the last edition of the _Origin of Species_. But as these "laws of +growth" refer to causes confessedly unknown, I will not occupy space by +discussing this division of our subject--further than to observe that, +as we shall subsequently see, many of the facts which fall under it are +so irreconcilably adverse to the Wallacean doctrine of specific +characters as universally adaptive, that in the face of them Mr. Wallace +himself appears at times to abandon his doctrine _in toto_. + + + + +CHAPTER IX. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_continued_). + + +It must have appeared strange that hitherto I should have failed to +distinguish between "true species" and merely "climatic varieties." But +it will conduce to clearness of discussion if we consider our subject +point by point. Therefore, having now given a fair statement of the +facts of climatic variation, I propose to deal with their theoretical +implications--especially as regards the distinction which naturalists +are in the habit of drawing between them and so-called true species. + +First of all, then, what is this distinction? Take, for example, the +case of the Porto Santo rabbits. To almost every naturalist who reads +what has been said touching these animals, it will have appeared that +the connexion in which they are adduced is wholly irrelevant to the +question in debate. For, it will be said that the very fact of the +seemingly specific differentiation of these animals having proved to be +illusory when some of them were restored to their ancestral conditions, +is proof that their peculiar characters are not specific characters; but +only what Mr. Wallace would term "individual characters," or variations +that are not _inherited_. And the same remark applies to all the other +cases which have been adduced to show the generality and extent of +climatic variation, both in other animals and also in plants. Why, then, +it will be asked, commit the absurdity of adducing such cases in the +present discussion? Is it not self-evident that however general, or +however considerable, such merely individual, or non-heritable, +variations may be, they cannot possibly have ever had anything to do +with the origin of _species_? Therefore, is it not simply preposterous +to so much as mention them in relation to the question touching the +utility of specific characters? + +Well, whether or not it is absurd and preposterous to consider climatic +variations in connexion with the origin of species, will depend, and +depend exclusively, on what it is that we are to understand by a +species. Hitherto I have assumed, for the sake of argument, that we all +know what is meant by a species. But the time has now come for showing +that such is far from being the case. And as it would be clearly absurd +and preposterous to conclude anything with regard to specific characters +before agreeing upon what we mean by a character as specific, I will +begin by giving all the logically possible definitions of a species. + +1. _A group of individuals descended by way of natural generation from +an originally and specially created type._ + +This definition may be taken as virtually obsolete. + +2. _A group of individuals which, while fully fertile_ inter se, _are +sterile with all other individuals--or, at any rate, do not generate +fully fertile hybrids._ + +This purely physiological definition is not nowadays entertained by any +naturalist. Even though the physiological distinction be allowed to +count for something in otherwise doubtful cases, no systematist would +constitute a species on such grounds alone. Therefore we need not +concern ourselves with this definition, further than to observe that it +is often taken as more or less supplementary to each of the following +definitions. + +3. _A group of individuals which, however many characters they share +with other individuals, agree in presenting one or more characters of a +peculiar kind, with some certain degree of distinctness._ + +In this we have the definition which is practically followed by all +naturalists at the present time. But, as we shall presently see more +fully, it is an extremely lax definition. For it is impossible to +determine, by any fixed and general rule, what degree of distinctness on +the part of peculiar characters is to be taken as a uniform standard of +specific separation. So long as naturalists believed in special +creation, they could feel that by following this definition (3) they +were at any rate doing their best to tabulate very real distinctions in +nature--viz. between types as originally produced by a supernatural +cause, and as subsequently more or less modified (i.e. within the limits +imposed by the test of cross-fertility) by natural causes. But +evolutionists are unable to hold any belief in such real distinctions, +being confessedly aware that all distinctions between species and +varieties are purely artificial. So to speak, they well know that it is +they themselves who create species, by determining round what degrees of +differentiation their diagnostic boundaries shall be drawn. And, seeing +that these degrees of differentiation so frequently shade into one +another by indistinguishable stages (or, rather, that they _always_ do +so, unless intermediate varieties have perished), modern naturalists are +well awake to the impossibility of securing any approach to a uniform +standard of specific distinction. On this account many of them feel a +pressing need for some firmer definition of a species than this +one--which, in point of fact, scarcely deserves to be regarded as a +definition at all, seeing that it does not formulate any definite +criterion of specific distinctness, but leaves every man to follow his +own standards of discrimination. Now, as far as I can see, there are +only two definitions of a species which will yield to evolutionists the +steady and uniform criterion required. These two definitions are as +follows. + +4. _A group of individuals which, however many characters they share +with other individuals, agree in presenting one or more characters of a +peculiar and hereditary kind, with some certain degree of distinctness._ + +It will be observed that this definition is exactly the same as the last +one, save in the addition of the words "and hereditary." But, it is +needless to say, the addition of these words is of the highest +importance, inasmuch as it supplies exactly that objective and rigid +criterion of specific distinctness which the preceding definition lacks. +It immediately gets rid of the otherwise hopeless wrangling over species +as "good" and "bad," or "true" and "climatic," of which (as we have +seen) Kerner's essay is such a remarkable outcome. Therefore +evolutionists have more and more grown to lay stress on the hereditary +character of such peculiarities as they select for diagnostic features +of specific distinctness. Indeed it is not too much to say that, at the +present time, evolutionists in general recognize this character as, +theoretically, indispensable to the constitution of a species. But it is +likewise not too much to say that, practically, no one of our systematic +naturalists has hitherto concerned himself with this matter. At all +events, I do not know of any who has ever taken the trouble to ascertain +by experiment, with regard to any of the species which he has +constituted, whether the peculiar characters on which his diagnoses have +been founded are, or are not, hereditary. Doubtless the labour of +constituting (or, still more, of _re_-constituting) species on such a +basis of experimental inquiry would be insuperable; while, even if it +could be accomplished, would prove undesirable, on account of the chaos +it would produce in our specific nomenclature. But, all the same, we +must remember that this nomenclature as we now have it--and, therefore, +the partitioning of species as we have now made them--has no reference +to the criterion of heredity. Our system of distinguishing between +species and varieties is not based upon the definition which we are now +considering, but upon that which we last considered--frequently coupled, +to some undefinable extent, with No. 2. + +5. There is, however, yet another and closer definition, which may be +suggested by the ultra-Darwinian school, who maintain the doctrine of +natural selection as the only possible cause of the origin of species, +namely:-- + +_A group of individuals which, however many characters they share with +other individuals, agree in presenting one or more characters of a +peculiar, hereditary, and adaptive kind, with some certain degree of +distinctness._ + +Of course this definition rests upon the dogma of utility as a necessary +attribute of characters _qua_ specific--i.e. the dogma against which the +whole of the present discussion is directed. Therefore all I need say +with reference to it is, that at any rate it cannot be adduced in any +argument where the validity of its basal dogma is in question. For it +would be a mere begging of this question to argue that every species +must present at least one peculiar and adaptive character, because, +according to definition, unless an organic type does present at least +one such character, it is not a specific type. Moreover, and quite apart +from this, it is to be hoped that naturalists as a body will never +consent to base their diagnostic work on what at best must always be a +highly speculative extension of the Darwinian theory. While, lastly, if +they were to do so with any sort of consistency, the precise adaptation +which each peculiar character subserves, and which because of this +adaptation is constituted a character of specific distinction, would +have to be determined by actual observation. For no criterion of +specific distinction could be more vague and mischievous than this one, +if it were to be applied on grounds of mere inference that such and such +a character, because seemingly constant, must "necessarily" be either +useful, vestigial, or correlated. + +Such then, as far as I can see, are all the definitions of a species +that are logically possible[122]. Which of them is chosen by those who +maintain the necessary usefulness of all specific characters? Observe, +it is for those who maintain this doctrine to choose their definition: +it is not for me to do so. My contention is, that the term does not +admit of any definition sufficiently close and constant to serve as a +basis for the doctrine in question--and this for the simple reason that +species-makers have never agreed among themselves upon any criterion of +specific distinction. My opponents, on the other hand, are clearly bound +to take an opposite view, because, unless they suppose that there is +some such definition of a species, they would be self-convicted of the +absurdity of maintaining a great generalization on a confessedly +untenable basis. For example, a few years ago I was allowed to raise a +debate in the Biological Section of the British Association on the +question to which the present chapters are devoted. But the debate ended +as I had anticipated that it must end. No one of the naturalists present +could give even the vaguest definition of what was meant by a +species--or, consequently, of a character as specific. On this account +the debate ended in as complete a destruction as was possible of the +doctrine that all the distinctive characters of every species must +necessarily be useful, vestigial, or correlated. For it became +unquestionable that the same generalization admitted of being made, with +the same degree of effect, touching all the distinctive characters of +every "snark." + + [122] It is almost needless to say that by a definition as "logical" + is meant one which, while including all the differentiae of + the thing defined, excludes any qualities which that thing may + share in common with any other thing. But by definitions as + "logically possible" I mean the number of separate definitions + which admit of being correctly given of the same thing from + different points of view. Thus, for instance, in the present + case, since the above has been in type the late M. + Quatrefages' posthumous work on _Darwin et ses Precurseurs + Francais_ has been published, and gives a long list of + definitions of the term "species" which from time to time have + been enunciated by as many naturalists of the highest standing + as such (pp. 186-187). But while none of these twenty or more + definitions is logical in the sense just defined, they all + present one or other of the differentiae given by those in the + text. + +Probably, however, it will be thought unfair to have thus sprung a +difficult question of definition in oral debate. Therefore I allude to +this fiasco at the British Association, merely for the purpose of +emphasizing the necessity of agreeing upon some definition of a species, +before we can conclude anything with regard to the generalization of +specific characters as necessarily due to natural selection. But when a +naturalist has had full time to consider this fundamental matter of +definition, and to decide on what his own shall be, he cannot complain +of unfairness on the part of any one else who holds him to what he thus +says he means by a species. Now Mr. Wallace, in his last work, has given +a matured statement of what it is that he means by a species. This, +therefore, I will take as the avowed basis of his doctrine touching the +necessary origin and maintenance of all specific characters by natural +selection. His definition is as follows:-- + + "An assemblage of individuals which have become somewhat modified + in structure, form, and constitution, _so as to adapt them to + slightly different conditions of life_; which can be differentiated + from allied assemblages; which reproduce their like; which usually + breed together; and, perhaps, when crossed with their near allies, + always produce offspring which are more or less sterile _inter + se_[123]." + + [123] Darwinism, p. 167. + +From this definition the portion which I have italicized must be omitted +in the present discussion, for the reasons already given while +considering definition No. 5. What remains is a combination of Nos. 2 +and 4. According to Mr. Wallace, therefore, our criterion of a species +is to be the heredity of peculiar characters, combined, perhaps, with a +more or less exclusive fertility of the component individuals _inter +se_. This is the basis on which his generalization of the utility of +specific characters as necessary and universal is reared. Here, then, we +have something definite to go upon, at all events as far as Mr. Wallace +is concerned. Let us see how far such a basis of definition is competent +to sustain his generalization. + +First of all it must be remarked that, as species have actually been +constituted by systematists, the test of exclusive fertility does not +apply. For my own part I think this is to be regretted, because I +believe that such is the only natural--and therefore the only +firm--basis on which specific distinctions can be reared. But, as +previously observed, this is not the view which has been taken by our +species-makers. At most they regard the physiological criterion as but +lending some additional weight to their judgement upon morphological +features, in cases where it is doubtful whether the latter alone are of +sufficient distinctness to justify a recognition of specific value. Or, +conversely, if the morphological features are clearly sufficient to +justify such a recognition, yet if it happens to be known that there is +full fertility between the form presenting them and other forms which do +not, then the latter fact will usually prevent naturalists from +constituting the well differentiated form a species on grounds of its +morphological features alone--as, for instance, in the case of our +domesticated varieties. In short, the physiological criterion has not +been employed with sufficient closeness to admit of its being now +comprised within any practical definition of the term "species"--if by +this term we are to understand, not what any one may think species +_ought to be_, but what species actually _are_, as they have been +constituted for us by their makers. + +From all this it follows that the definition of the term "species" on +which Mr. Wallace relies for his deduction with respect to specific +characters, is the definition No. 4. In other words, omitting his +_petitio principii_ and his allusion to the test of fertility, the great +criterion in his view is the criterion of Heredity. And in this all +other evolutionists, of whatever school, will doubtless agree with him. +They will recognize that it is really the distinguishing test between +"climatic varieties" and "true species," so that however widely or +however constantly the former may diverge from one another in regard to +their peculiar characters, they are not to be classed among the latter +unless their peculiar characters are likewise hereditary characters. + +Now, if we are all agreed so far, the only question that remains is +whether or not this criterion of Heredity is capable of supplying a +basis for the generalization, that all characters which have been ranked +as of specific value must necessarily be regarded as presenting also an +adaptive, or life-serving, value? I will now endeavour to show that +there are certain very good reasons for answering this question in the +negative. + + +(A.) + +In the first place, even if the modifications induced by the direct +action of a changed environment are not hereditary, who is to know that +they are not? Assuredly not the botanist or zoologist who in a +particular area finds what he is fully entitled to regard as a +well-marked specific type. Only by experiments in transposition could it +be proved that the modifications have been produced by local conditions; +and although the researches of many experimentalists have shown how +considerable and how constant such modifications may be, where is the +systematic botanist who would ever think of transplanting an apparently +new species from one distant area to another before he concludes that it +is a new species? Or where is the systematic zoologist who would take +the trouble to transport what appears to be an obviously endemic species +of animal from one country to another before venturing to give it a new +specific name? No doubt, both in the case of plants and animals, it is +tacitly assumed that constant differences, if sufficient in amount to be +regarded as specific differences are hereditary; but there is not one +case in a hundred where the validity of this assumption has ever been +tested by experiments in transposition. Therefore naturalists are apt to +regard it as remarkable when the few experiments which have been made in +this direction are found to negative their assumption--for example, +that a diagnostic character in species of the genus _Hieratium_ is found +by transplantation not to be hereditary, or that the several named +species of British trout are similarly proved to be all "local +varieties" of one another. But, in point of fact, there ought to be +nothing to surprise us in such results--unless, indeed, it is the +unwarrantable nature of the assumption that any given differences of +size, form, colour, &c., which naturalists may have regarded as of +specific value, are, on this account, hereditary. Indeed, so surprising +is this assumption in the face of what we know touching both the extent +and the constancy of climatic variation, that it seems to me such a +naturalist as Kerner, who never considers the criterion of heredity at +all, is less assailable than those who profess to constitute this their +chief criterion of specific distinction. For it is certain that whatever +their professions may have nowadays become, systematic naturalists have +never been in the habit of really following this criterion. In theory +they have of late years attached more and more weight to definition No. +4; but in practice they have always adopted definition No. 3. The +consequence is, that in literally numberless cases (particularly in the +vegetable kingdom) "specific characters" are assumed to be hereditary +characters merely because systematic naturalists have bestowed a +specific name on the form which presents them. Nor is this all. For, +conversely, even when it is known that constant morphological characters +are unquestionably hereditary characters, if they happen to present but +small degrees of divergence from those of allied forms, then the form +which presents them is not ranked as a species, but as a constant +variety. In other words, when definitions 3 and 4 are found to clash, it +is not 4, but 3, that is followed. In short, even up to the present +time, systematic naturalists play fast and loose with the criterion of +Heredity to such an extent, that, as above observed, it has been +rendered wellnigh worthless in fact, whatever may be thought of it in +theory. + +Now, unless all this can be denied, what is the use of representing that +a species is distinguished from a variety--"climatic" or otherwise--by +the fact that its constituent individuals "reproduce their like"? We are +not here engaged on any abstract question of what might have been the +best principles of specific distinction for naturalists to have adopted. +We are engaged on the practical question of the principles which they +actually have adopted. And of these principles the reproduction of like +by like, under all circumstances of environment, has been virtually +ignored. + + +(B.) + +In the second place, supposing that the criterion of Heredity had been +as universally and as rigidly employed by our systematists in their work +of constructing species as it has been but occasionally and loosely +employed, could it be said that even then a basis would have been +furnished for the doctrine that all specific characters must necessarily +be useful characters? Obviously not, and for the following reasons. + +It is admitted that climatic characters are not necessarily--or even +generally--useful characters. Consequently, if there be any reason for +believing that climatic characters may become in time hereditary +characters, the doctrine in question would collapse, even supposing that +all specific types were to be re-constituted on a basis of experimental +inquiry, for the purpose of ascertaining which of them conform to the +test of Heredity. Now there are very good reasons for believing that +climatic characters not unfrequently do become hereditary characters; +and it was mainly in view of those reasons that I deemed it worth while +to devote so much space in the preceding chapter to the facts of +climatic variation. I will now state the reasons in question under two +different lines of argument. + +We are not as yet entitled to conclude definitely against the possible +inheritance of acquired characters. Consequently, we are not as yet +entitled to assume that climatic characters--i. e. characters acquired +by converse with a new environment, continued, say, since the last +glacial period--can never have become congenital characters. But, if +they ever have become congenital characters, they will have become, at +all events as a general rule, congenital characters that are useless; +for it is conceded that, _qua_ climatic characters, they have not been +due to natural selection. + +Doubtless the followers of Weismann will repudiate this line of +argument, if not as entirely worthless, at all events as too +questionable to be of much practical worth. But even to the followers of +Weismann it may be pointed out, that the Wallacean doctrine of the +origin of all specific characters by means of natural selection was +propounded many years before either Galton or Weismann had questioned +the transmission of acquired characters. However. I allow that this line +of argument has now become--for the time being at all events--a dubious +line, and will therefore at once pass on to the second line, which is +not open to doubt from any quarter. + +Whether or not we accept Weismann's views, it will here be convenient to +employ his terminology, since this will serve to convey the somewhat +important distinctions which it is now my object to express. + +In the foregoing paragraphs, under heading (A), we have seen that there +must be "literally numberless forms" which have been ranked as true +species, whose diagnostic characters are nevertheless not congenital. In +the case of plants especially, we know that there must be large numbers +of named species which do not conform to the criterion of Heredity, +although we do not know which species they are. For present purposes, +however, it is enough for us to know that there are many such named +species, where some change of environment has acted directly and +similarly on all the individual "somas" exposed to it, without affecting +their "germ-plasms," or the material bases of their hereditary +qualities. For named species of this kind we may employ the term +_somatogenetic species_. + +But now, if there are any cases where a change of environment does act +on the germ-plasms exposed to it, the result would be what we may call +_blastogenetic species_--i.e. species which conform to the criterion of +Heredity, and would therefore be ranked by all naturalists as "true +species." It would not signify in such a case whether the changed +conditions of life first affected the soma, and then, through changed +nutrition, the germ-plasm; or whether from the first it directly +affected the germ-plasm itself. For in either case the result would be a +"species," which would continue to reproduce its peculiar features by +heredity. + +Now, the supposition that changed conditions of life may thus affect the +congenital endowments of germ-plasm is not a gratuitous one. The sundry +facts already given in previous chapters are enough to show that the +origin of a blastogenetic species by the direct action on germ-plasm of +changed conditions of life is, at all events, a possibility. And a +little further thought is enough to show that this possibility becomes a +probability--if not a virtual certainty. Even Weismann--notwithstanding +his desire to maintain, as far as he possibly can, the "stability" of +germ-plasm--is obliged to allow that external conditions acting on the +organism may in some cases modify the hereditary qualities of its +germ-plasm, and so, as he says, "determine the phyletic development of +its descendants." Again, we have seen that he is compelled to interpret +the results of his own experiments on the climatic varieties of certain +butterflies by saying, "I cannot explain the facts otherwise than by +supposing the passive acquisition of characters produced by direct +influences of climate"; by which he means that in this case the +influence of climate acts directly on the hereditary qualities of +germ-plasm. Lastly, and more generally, he says:-- + + "But although I hold it improbable that individual variability can + depend on a direct action of external influences upon the + germ-cells and their contained germ-plasm, because--as follows from + sundry facts--the molecular structure of the germ-plasm must be + very difficult to change, yet it is by no means to be implied that + this structure may not possibly be altered by influences of the + same kind continuing for a very long time. Thus it seems to me the + possibility is not to be rejected, that influences continued for a + long time, that is, for generations, such as temperature, kind of + nourishment, &c., which may affect the germ-cells as well as any + other part of the organism, may produce a change in the + constitution of the germ-plasm. But such influences would not then + produce individual variation, but would necessarily modify in the + same way all the individuals of a species living in a certain + district. It is possible, though it cannot be proved, that many + climatic varieties have arisen in this manner." + +So far, then, we have testimony to this point, as it were, from a +reluctant witness. But if we have no theory involving the "stability of +germ-plasm" to maintain, we can scarcely fail to see how susceptible the +germ-plasm is likely to prove to changed conditions of life. For we know +how eminently susceptible it is in this respect when gauged by the +practical test of fertility; and as this is but an expression of its +extraordinarily complex character, it would indeed be surprising if it +were to enjoy any immunity against modification by changed conditions of +life. We have seen in the foregoing chapter how frequently and how +considerably somatogenetic changes are thus caused, so as to produce +"somatogenetic species"--or, where we happen to know that the changes +are not hereditary, "climatic varieties." But the constitution of +germ-plasm is much more complex than that of any of the structures which +are developed therefrom. Consequently, the only wonder is that hitherto +experimentalists have not been more successful in producing +"blastogenetic species" by artificial changes of environment. Or, as Ray +Lankester has well stated this consideration, "It is not difficult to +suggest possible ways in which the changed conditions, shown to be +important by Darwin, could act through the parental body upon the +nuclear matter of the egg-cell and sperm-cell, with its immensely +complex and therefore unstable constitution.... The wonder is, not that +[blastogenetic] variation occurs, but that it is not excessive and +monstrous in every product of fertilization[124]." + + [124] _Nature_, Dec. 12, 1889, p. 129. + +If to this it should be objected that, as a matter of fact, +experimentalists have not been nearly so successful in producing +congenital modifications of type by changed conditions of life as they +have been in thus producing merely somatic modifications; or if it +should be further objected that we have no evidence at all in nature of +a "blastogenetic species" having been formed by means of climatic +influences alone,--if these objections were to be raised, they would +admit of the following answer. + +With regard to experiments, so few have thus far been made upon the +subject, that objections founded on their negative results do not carry +much weight--especially when we remember that these results have not +been uniformly negative, but sometimes positive, as shown in Chapter VI. +With regard to plants and animals in a state of nature, the objection is +wholly futile, for the simple reason that in as many cases as changed +conditions of life may have caused an hereditary change of specific +type, there is now no means of obtaining "evidence" upon the subject. +But we are not on this account entitled to conclude against the +probability of such changes of specific type having been more or less +frequently thus produced. And still less can we be on this account +entitled to conclude against the _possibility_ of such a change having +ever occurred in any single instance. Yet this is what must be concluded +by any one who maintains that the origin of all species--and, _a +fortiori_, of all specific characters--must _necessarily_ have been due +to natural selection. + +Now, if all this be admitted--and I do not see how it can be reasonably +questioned--consider how important its bearing becomes on the issue +before us. If germ-plasm (using this term for whatever it is that +constitutes the material basis of heredity) is ever capable of having +its congenital endowments altered by the direct action of external +conditions, the resulting change of hereditary characters, whatever else +it may be, need not be an adaptive change. Indeed, according to +Weismann's theory of germ-plasm, the chances must be infinitely against +the change being an adaptive one. On the theory of pangenesis--that is +to say, on the so-called Lamarckian principles--there would be much more +reason for entertaining the possibly adaptive character of hereditary +change due to the direct action of the environment. Therefore we arrive +at this curious result. The more that we are disposed to accept +Weismann's theory of heredity, and with it the corollary that natural +selection is the sole cause of adaptive modification in species the less +are we entitled to assume that all specific characters must necessarily +be adaptive. Seeing that in nature there are presumably many cases like +those of Hoffmann's plants, Weismann's butterflies, &c., where the +hereditary qualities of germ-plasm have (on his hypothesis) been +modified by changed conditions of life, we are bound to believe that, in +all cases where such changes do not happen to be actively deleterious, +they will persist. And inasmuch as characters which are only of +"specific" value must be the characters most easily--and therefore most +frequently--induced by any slight changes in the constitution of +germ-plasm, while, for the same reason (namely, that of their trivial +nature) they are least likely to prove injurious, it follows that the +less we believe in the functionally-produced adaptations of Lamarck, the +more ought we to resist the assumption that all specific characters must +necessarily be adaptive characters. + + * * * * * + +Upon the whole, then, and with regard to the direct action of external +conditions, I conclude--not only from general considerations, but also +from special facts or instances quite sufficient for the purpose--that +these must certainly give rise to immense numbers of somatogenetic +species on the one hand, and probably to considerable numbers of +blastogenetic species on the other; that in neither case is there any +reason for supposing the distinctively "specific characters" to be other +than "neutral" or "indifferent"; while there are the best of reasons for +concluding the contrary. So that, under this division of our subject +alone (B), there appears to be ample justification for the statement +that "a large proportional number of specific characters" are in +reality, as they are in appearance, destitute of significance from a +utilitarian point of view. + + +(C.) + +Thus far in the present chapter we have been dealing exclusively with +the case of "climatic variation," or change of specific type due to +changes in the external conditions of life. But it will be remembered +that, in the preceding chapter, allusion was likewise made to changes of +specific type due to internal causes, or to what Darwin has called "the +nature of the organism." Under this division of our subject I mentioned +especially Sexual Selection, which is supposed to arise in the aesthetic +taste of animals themselves; Isolation, which is supposed to originate +new types by allowing the average characters of an isolated section of +an old type to develop a new history of varietal change, as we shall see +more fully in the ensuing part of this treatise; and the Laws of Growth, +which is a general term for the operation of unknown causes of change +incidental to the living processes of organisms which present the +change. + +Now, under none of these divisions of our subject can there be any +question touching the criterion of Heredity. For if new species--or even +single specific characters of new species--are ever produced by any of +these causes, they must certainly all "reproduce their like." Therefore +the only question which can here obtain is as to whether or not such +causes ever do originate new species, or even so much as new specific +characters. Mr. Wallace, though not always consistently, answers this +question in the negative; but the great majority of naturalists follow +Darwin by answering it in the affirmative. And this is enough to show +the only point which we need at present concern ourselves with +showing--viz. that the question is, at the least, an open one. For as +long as this question is an open one among believers in the theory of +natural selection, it must clearly be an unwarrantable deduction from +that theory, that all species, and _a fortiori_ all specific characters, +are necessarily due to natural selection. The deduction cannot be +legitimately drawn until the possibility of any other cause of specific +modification has been excluded. But the bare fact of the question as +just stated being still and at the least an open question, is enough to +prove that this possibility has not been excluded. Therefore the +deduction must be, again on this ground alone (C), unwarrantable. + + * * * * * + +Such are my several reasons--and it is to be observed that they are all +_independent_ reasons--for concluding that it makes no practical +difference to the present discussion whether or not we entertain +Heredity as a criterion of specific distinction. Seeing that our +species-makers have paid so little regard to this criterion, it is +neither absurd nor preposterous to have adduced, in the preceding +chapter, the facts of climatic variation. On the contrary, as the +definition of "species" which has been practically followed by our +species-makers in No. 3, and not No. 4, these facts form part and parcel +of our subject. It is perfectly certain that, in the vegetable kingdom +at all events, "a large proportional number" of specifically diagnostic +characters would be proved by experiment to be "somatogenetic"; while +there are numerous constant characters classed as varietal, although it +is well known that they are "blastogenetic." Moreover, we can scarcely +doubt that many specific characters which are also hereditary characters +owe their existence, not to natural selection, but to the direct action +of external causes on the hereditary structure of "germ-plasm"; while, +even apart from this consideration, there are at least three distinct +and highly general principles of specific change, which are accepted by +the great majority of Darwinists, and the only common peculiarity of +which is that they produce hereditary changes of specific types without +any reference to the principle of utility. + + + + +CHAPTER X. + +CHARACTERS AS ADAPTIVE AND SPECIFIC +(_concluded_). + + +Our subject is not yet exhausted. For it remains to observe the +consequences which arise from the dogma of utility as the only _raison +d'etre_ of species, or of specific characters, when this dogma is +applied in practice by its own promoters. + + * * * * * + +Any definition of "species"--excepting Nos. 1, 2, and 5, which may here +be disregarded--must needs contain some such phrase as the one with +which Nos. 3 and 4 conclude. This is, that peculiar characters, in order +to be recognized as of specific value, must present neither more nor +less than "some certain degree of distinctness." If they present more +than this degree of distinctness, the form, or forms, in question must +be ranked as generic; while if they present less than this degree of +distinctness, they must be regarded as varietal--and this even if they +are known to be mutually sterile. What, then, is this certain degree of +distinctness? What are its upper and lower limits? This question is one +that cannot be answered. From the very nature of the case it is +impossible to find a uniform standard of distinction whereby to draw +our boundary lines between varieties and species on the one hand, or +between species and genera on the other. One or two quotations will be +sufficient to satisfy the general reader upon this point. + +Mr. Wallace himself alludes to "the great difficulty that is felt by +botanists in determining the limits of species in many large genera," +and gives as examples well-known instances where systematic botanists of +the highest eminence differ hopelessly in their respective estimates of +"specific characters." Thus:-- + + "Mr. Baker includes under a single species, Rosa canina, no less + than twenty-eight named varieties distinguished by more or less + constant characters, and often confined to special localities, and + to these are referred about seventy of the species of British and + continental botanists. Of the genus Rubus or bramble, five British + species are given in Bentham's _Handbook of British Flora_, while + in the fifth edition of Babington's _Manual of British Botany_, + published about the same time, no less than forty-five species are + described. Of willows (Salix) the same two works enumerate fifteen + and thirty-one species respectively. The hawkweeds (Hieracium) are + equally puzzling, for while Mr. Bentham admits only seven British + species, Professor Babington describes no less than seventy-two, + besides several named varieties[125]." + + [125] _Darwinism_, p. 77. + +Mr. Wallace goes on to quote further instances, such as that of Draba +verna, which Jordan has found to present, in the south of France alone, +no less than fifty-two permanent varieties, which all "come true from +seed, and thus present all the characteristics of a true species"; so +that, "as the plant is very common almost all over Europe, and ranges +from North America to the Himalayas, the number of similar forms over +this wide area would probably have to be reckoned by hundreds, if not by +thousands[126]." + + [126] _Darwinism_, p. 77. + +One or two further quotations may be given to the same general effect, +selected from the writings of specialists in their several departments. + + "There is nothing that divides systematists more than what + constitutes a genus. Species that resemble each other more than + other species, is perhaps the best definition that can be given. + This is obviously an uncertain test, much depending on individual + judgement and experience; but that, in the evolution of forms, such + difficulties should arise in the limitation of genera and species + was inevitable. What is a generic character in one may be only a + specific character in another. As an illustration of the uncertain + importance of characters, I may mention the weevil genus + _Centrinus_ in which the leading characters in the classification + of the family to which it belongs are so mixed that systematists + have been content to keep the species together in a group that + cannot be defined.... No advantage or disadvantage is attached, + apparently, to any of the characters. There are about 200 species, + all American. + + The venation of the wings of insects is another example of + modifications without serving any special purpose. There is no vein + in certain Thripidae, and only a rudiment or a single vein in + Chalcididae. There are thousands of variations more or less marked, + some of the same type with comparatively trivial variation, others + presenting distinct types, even in the same family, such genera, + for example, as _Polyneura_, _Tettigetra_, _Huechys_, &c. in the + Cicadidae. + + Individual differences have often been regarded as distinctive of + species; varieties also are very deceptive, and races come very + near to species. A South-American beetle, _Arescus histrio_, has + varieties of yellow, red, and black, or these colours variously + intermixed, and, what is very unusual, longitudinal stripes in some + and transverse bars in others, and all taken in the same locality. + Mr. A. G. Butler, of the British Museum, is of opinion that 'what + is generally understood by the term species (that is to say, a + well-defined, distinct, and constant type, having no near allies) + is non-existent in the Lepidoptera, and that the nearest approach + to it in this order is a constant, though but slightly differing, + rare or local form--that genera, in fact, consist wholly of a + gradational series of such forms (Ann. Mag. Nat. Hist. 5, xix. + 103)[127].'" + + [127] Pascoe, _The Darwinian Theory of the Origin of Species_, 1891, + pp. 31-33, and 46. + +So much as regards entomology, and still living forms. In illustration +of the same principles in connexion with palaeontological series, I may +quote Wuertenberger, who says:-- + + "With respect to these fossil forms [i.e. multitudinous forms of + fossil Ammonites], it is quite immaterial whether a very short or a + somewhat longer part of any branch be dignified with a separate + name, and regarded as a species. The prickly Ammonites, classed + under the designation of Armata, are so intimately connected that + it becomes impossible to separate the accepted species sharply from + one another. The same remark applies to the group of which the + manifold forms are distinguished by their ribbed shells, and are + called Planulata[128]." + + [128] _Neuer Beitrag zum geologischen Beweis der Darwinischen + Theorie_, 1873. + +I had here supplied a number of similar quotations from writers in +various other departments of systematic work, but afterwards struck them +out as superfluous. For it is not to be anticipated that any competent +naturalist will nowadays dispute that the terms "variety," "species," +and "genus" stand for merely conventional divisions, and that whether a +given form shall be ranked under one or the other of them is often no +more than a matter of individual taste. From the nature of the case +there can be no objective, and therefore no common, standards of +delimitation. This is true even as regards any one given department of +systematic work; but when we compare the standards of delimitation which +prevail in one department with those which prevail in another, it +becomes evident that there is not so much as any attempt at agreeing +upon a common measure of specific distinction. + +But what, it may well be asked, is the use of thus insisting upon +well-known facts, which nobody will dispute? Well, in the first place, +we have already seen, in the last chapter, that it is incumbent on those +who maintain that all species, or even all specific characters, must be +due to natural selection, to tell us what they mean by a species, or by +characters as specific. If I am told to believe that the definite +quality A is a necessary attribute of B, and yet that B is "not a +distinct entity," but an undefinable abstraction, I can only marvel that +any one should expect me to be so simple. But, without recurring to this +point, the use of insisting on the facts above stated is, in the second +place, that otherwise I cannot suppose any general reader could believe +them in view of what is to follow. For he cannot but feel that the cost +of believing them is to render inexplicable the mental processes of +those naturalists who, in the face of such facts, have deduced the +following conclusions. + +The school of naturalists against which I am contending maintains, as a +generalization deduced from the theory of natural selection, that all +species, or even all specific characters, must necessarily owe their +origin to the principle of utility. Yet this same school does not +maintain any such generalization, either with regard to varietal +characters on the one hand, or to generic characters on the other. On +the contrary, Professor Huxley, Mr. Wallace, and all other naturalists +who agree with them in refusing to entertain so much as the abstract +possibility of any cause other than natural selection having been +productive of species, fully accept the fact of other causes having been +largely concerned in the production of varieties, genera, families, and +all higher groups, or of the characters severally distinctive of each. +Indeed, Mr. Wallace does not question what appears to me the extravagant +estimate of Professor Cope, that the non-adaptive characters distinctive +of those higher groups are fully equal, in point of numbers, to the +adaptive. But, surely, if the theory of evolution by natural selection +is, as we all agree, a true theory of the origin of species, it must +likewise be a true theory of the origin of genera; and if it be supposed +essential to the integrity of the theory in its former aspect that all +specific characters should be held to be useful, I fail to see how, in +regard to its latter aspect, we are so readily to surrender the +necessary usefulness of all generic characters. And exactly the same +remark applies to the case of constant "varieties," where again the +doctrine of utility as universal is not maintained. Yet, according to +the general theory of evolution, constant varieties are what Darwin +termed "incipient species," while species are what may be termed +"incipient genera." Therefore, if the doctrine of utility as universal +be conceded to fail in the case of varieties on the one hand and of +genera on the other, where is the consistency in maintaining that it +must "necessarily" hold as regards the intermediate division, species? +Truly the shade of Darwin may exclaim, "Save me from my friends." And +truly against logic of this description a follower of Darwin must find +it difficult to argue. If one's opponents were believers in special +creation, and therefore stood upon some definite ground while +maintaining this difference between species and all other taxonomic +divisions, there would at least be some issue to argue about. But when +on the one hand it is conceded that species are merely arbitrary +divisions, which differ in no respect as to the process of their +evolution from either varieties or genera, while on the other hand it is +affirmed that there is thus so great a difference in the result, all we +can say is that our opponents are entangling themselves in the meshes of +a sheer contradiction. + +Or, otherwise stated, specific characters differ from varietal +characters in being, as a rule, more pronounced and more constant: on +this account advocates of utility as universal apply the doctrine to +species, while they do not feel the "necessity" of applying it to +varieties. But now, generic and all higher characters are even more +constant and more pronounced than specific characters--not to say, in +many cases, more generally diffused over a larger number of organisms +usually occupying larger areas. Therefore, _a fortiori_, if for the +reasons above stated evolutionists regard it as a necessary deduction +from the theory of natural selection that all specific characters must +be useful, much more ought it to be a necessary deduction from this +theory that all generic, and still more all higher, characters must be +useful. But, as we have seen, this is not maintained by our opponents. +On the contrary, they draw the sharpest distinction between specific and +all other characters in this respect, freely conceding that both those +below and those above them need not--and very often do not--present any +utilitarian significance. + +Although it appears to me that this doctrine is self-contradictory, and +on this ground alone might be summarily dismissed, as it is now held in +one or other of its forms by many naturalists, I will give it a more +detailed consideration in both its parts--namely, first with respect to +the distinction between varieties and species, and next with respect to +the distinction between species and genera. + + * * * * * + +Until it can be shown that species are something more than merely +arbitrary divisions, due to the disappearance of intermediate varietal +links; that in some way or another they _are_ "definite entities," which +admit of being delineated by the application of some uniform or general +principles of definition; that, in short, species have only then been +classified as such when it has been shown that the origin of each has +been due to the operation of causes which have not been concerned in the +production of varieties;--until these things are shown, it clearly +remains a gratuitous dogma to maintain that forms which have been called +species differ from forms which have been called varieties in the +important respect, that they (let alone each of all their distinctive +characters) must necessarily have been due to the principle of utility. +Yet, as we have seen, even Mr. Wallace allows that a species is "not a +distinct entity," but "an assemblage of individuals which have become +somewhat modified in structure, form, and constitution"; while estimates +of the kinds and degrees of modification which are to be taken as of +specific value are conceded to be undefinable, fluctuating, and in not a +few cases almost ludicrously divergent. + +Perhaps one cannot more forcibly present the rational value of this +position than by noting the following consequences of it. Mr. Gulick +writes me that while studying the land-shells of the Sandwich Islands, +and finding there a rich profusion of unique varieties, in cases where +the intermediate varieties were rare he could himself have created a +number of species by simply throwing these intermediate varieties into +his fire. Now it follows from the dogma which we are considering, that, +by so doing, not only would he have created new species, but at the same +time he would have proved them due to natural selection, and endowed the +diagnostic characters of each with a "necessarily" adaptive meaning, +which previously it was not necessary that they should present. Before +his destruction of these intermediate varieties, he need have felt +himself under no obligation to assume that any given character at either +end of the series was of utilitarian significance: but, after his +destruction of the intermediate forms, he could no longer entertain any +question upon the matter, under pain of being denounced as a Darwinian +heretic. + +Now the application is self-evident. It is a general fact, which admits +of no denial, that the more our knowledge of any flora or fauna +increases, the greater is the number of intermediate forms which are +brought to light, either as still existing or as having once existed. +Consequently, the more that such knowledge increases, the more does our +catalogue of "species" diminish. As Kerner says, "bad species" are +always multiplying at the expense of "good species"; or, as Oscar +Schmidt (following Haeckel) similarly remarks, if we could know as much +about the latter as we do about the former, "all species, without any +exception, would become what species-makers understand by 'bad +species'[129]." Hence we see that, just as Mr. Gulick could have created +good species by secretly destroying his intermediate varieties, so has +Nature produced her "good species" for the delectation of systematists. +And just as Mr. Gulick, by first hiding and afterwards revealing his +intermediate forms, could have made the self-same characters in the +first instance necessarily useful, but ever afterwards presumably +useless, so has Nature caused the utility of diagnostic characters to +vary with our knowledge of her intermediate forms. It belongs to the +essence of our theory of descent, that in _all_ cases these intermediate +forms must either be now existing or have once existed; and, therefore, +that the work of species-makers consists in nothing more than marking +out the _lacunae_ in our knowledge of them. Yet we are bound to believe +that wherever these _lacunae_ in our knowledge occur, there occurs also +the objective necessity of causation as utilitarian--a necessity, +however, which vanishes so soon as our advancing information supplies +the intermediate forms in question. It may indeed appear strange that +the utility or non-utility of organic structures should thus depend on +the accidents of human knowledge; but this is the Darwinian faith, and +he who doubts the dogma is to be anathema. + + [129] _The Doctrine of Descent and Darwinism_, Eng. Trans. p. 102. + +Turning next to the similar distinction which it is sought to draw +between species and genera, here it will probably be urged, as I +understand it to be urged by Mr. Wallace, that generic characters (and +still more characters of families, orders, &c.) refer back to so remote +a state of things that utility may have been present at their birth +which has disappeared in their maturity. In other words, it is held that +all generic characters were originally specific characters; that as such +they were all originally of use; but that, after having been rendered +stable by heredity, many of them may have ceased to be of service to the +descendants of those species in which they originated, and whose +extinction has now made it impossible to divine what that service may +have been. + +Now, in the first place; this is not the interpretation adopted by +Darwin. For instance, he expressly contrasts such cases with those of +vestigial or "rudimentary" structures, pointing out that they differ +from vestigial structures in respect of their permanence. One quotation +will be sufficient to establish the present point. + + "A structure which has been developed through long-continued + selection, when it ceases to be of service to a species, generally + becomes variable, as we see with rudimentary organs, for it will no + longer be regulated by this same power of selection. But when, from + the nature of the organism and of the conditions, modifications + have been induced which are unimportant for the welfare of the + species, they may be, and apparently often have been, transmitted + in nearly the same state to numerous, otherwise modified, + descendants[130]." + + [130] _Origin of Species_, p. 175. + +Here, and in the context, we have a sufficiently clear statement of +Darwin's view--first, that unadaptive characters may arise in _species_ +as "fluctuating variations, which sooner or later become _constant_ +through the nature of the organism and of surrounding conditions, as +well as through the intercrossing of distinct individuals, but _not_ +through natural selection"[131]; second, that such unadaptive characters +may then be transmitted in this their stable condition to +species-progeny, so as to become distinctive of genera, families, &c.; +third, that, on account of such characters not being afterwards liable +to diverse adaptive modifications in different branches of the +species-progeny, they are of more value as indicating lines of pedigree +than are characters which from the first have been useful; and, lastly, +they are therefore now empirically recognized by systematists as of most +value in guiding the work of classification. To me it appears that this +view is not only perfectly rational in itself, but likewise fully +compatible with the theory of natural selection--which, as I have +previously shown, is _primarily_ a theory of adaptive characters, and +therefore not necessarily a theory of _all_ specific characters. But to +those who think otherwise, it must appear--and does appear--that there +is something wrong about such a view of the case--that it was not +consistent in the author of the _Origin of Species_ thus to refer +non-adaptive generic characters to a parentage of non-adaptive specific +characters. Nevertheless, as a matter of fact, Darwin was perfectly +consistent in putting forth this view, because, unlike Wallace, he was +not under the sway of any antecedent dogma erroneously deduced from the +theory of natural selection. + + [131] _Ibid._ p. 176: italics mine. + +Next without reference to Darwin's authority, let us see for ourselves +where the inconsistency really lies. To allow that generic characters +may be useless, while denying that specific characters can ever be so +(unless correlated with others that are useful), involves an appeal to +the argument from ignorance touching the ancestral habits, +life-conditions, &c., of a parent species now extinct. Well, even upon +this assumption of utility as obsolete, there remains to be explained +the "stability" of useless characters now distinctive of genera, +families, orders, and the rest. We know that specific characters which +have owed their origin to utility and have afterwards ceased to present +utility, degenerate, become variable, inconstant, "rudimentary," and +finally disappear. Why, then, should these things not happen with regard +to useless generic distinctions? Still more, why should they not happen +with regard to family, ordinal, and class distinctions? On the lines +against which I am arguing it would appear impossible that any answer to +this question can be suggested. For what explanation can be given of the +contrast thus presented between the obsolescence of specific characters +where previous utility is demonstrable, and the permanence of higher +characters whose previous utility is assumed? As we have already seen, +Mr. Wallace himself employs this consideration of permanence and +constancy against the view that any cause other than natural selection +can have been concerned in the origin and maintenance of _specific_ +characters. But he does not seem to see that the consideration cuts two +ways--and much more forcibly against his views than in favour of them. +For while, as already shown in the chapter before last, it is +sufficiently easy to dispose of the consideration as Wallace uses it (by +simply pointing out with Darwin that any causes other than natural +selection which may have been concerned in the genesis of _specific_ +characters, must, if equally uniform in their operation, equally give +rise to permanence and constancy in their results); on the other hand, +it becomes impossible to explain the stability of useless _generic_ +characters, if, as Wallace's use of the argument requires, natural +selection is the only possible cause of stability. The argument is one +that cannot be played with fast and loose. Either utility is the sole +condition to the stability of _any_ diagnostic character (in which case +it is not open to Mr. Wallace to assume that all _generic_ or higher +characters which are now useless have owed their origin to a past +utility); or else utility is not the sole condition to stability (in +which case his use of the present argument in relation to _specific_ +characters collapses). We have seen, indeed, in the chapter before last, +that his use of the argument collapses anyhow, or quite irrespective of +his inconsistent attitude towards generic characters, with which we were +not then concerned. But the point now is that, as a mere matter of +logic, the argument from stability as Wallace applies it to the case of +specific characters, is incompatible with his argument that useless +generic characters may originally have been useful specific characters. +It can scarcely be questioned that the transmutation of a species into a +genus must, as a rule, have allowed time enough for a newly +acquired--i.e. peculiar specific-character--to show some signs of +undergoing degeneration, if, as supposed, the original cause of its +development and maintenance was withdrawn when the parent species began +to ramify into its species-progeny. Yet, as Darwin says, "it is +notorious that specific characters are more variable than generic[132]." +So that, upon the whole, I do not see how on grounds of general +reasoning it is logically possible to maintain Mr. Wallace's distinction +between specific and generic characters in respect of necessary utility. + + [132] _Origin of Species_, p. 122. + +But now, and lastly, we shall reach the same conclusion if, discarding +all consideration of general principles and formal reasoning, we fasten +attention upon certain particular cases, or concrete facts. Thus, to +select only two illustrations within the limits of genera, it is a +diagnostic feature of the genus _Equus_ that small warty callosities +occur on the legs. It is impossible to suggest any useful function that +is now discharged by these callosities in any of the existing species of +the genus. If it be assumed that they must have been of some use to the +species from which the genus originally sprang, the assumption, it seems +to me, can only be saved by further assuming that in existing species of +the genus these callosities are in a vestigial condition--i. e. that in +the original or parent species they performed some function which is +now obsolete. But against these assumptions there lies the following +fact. The callosities in question are not similarly distributed through +all existing species of the genus. The horse has them upon all his four +legs, while other species have them only upon two. Therefore, if all +specific characters are necessarily due to natural selection, it is +manifest that these callosities are _not_ now vestigial: on the +contrary, they _must_ still be--or, at best, have recently been--of so +much importance to all existing species of the genus, that not only is +it a matter of selection-value to all these species that they should +possess these callosities; but it is even a matter of selection-value to +a horse that he should possess four of them, while it is equally a +matter of selection-value to the ass that he should possess only two. +Here, it seems to me, we have once more the doctrine of the necessary +utility of specific characters reduced to an absurdity; while at the +same time we display the incoherency of the distinction between specific +characters and generic characters in respect of this doctrine. For the +distinction in such a case amounts to saying that a generic character, +if evenly distributed among all the species, need not be an adaptive +character; whereas, if any one of the species presents it in a slightly +different form, the character must be, on this account, necessarily +adaptive. In other words, the uniformity with which a generic character +occurs among the species of the genus is taken to remove that character +from the necessarily useful class, while the absence of such uniformity +is taken as proof that the character must be placed within the +necessarily useful class. Which is surely no less a _reductio ad +absurdum_ with regard to the generic character than the one just +presented with regard to its variants as specific characters. And, of +course, this twofold absurdity is presented in all cases where a generic +character is unequally distributed among the constituent species of a +genus. + +[Illustration: Fig. 4.--Lower Teeth of Orang (after Tomes).] + +But here is an illustration of another class of cases. Mr. Tomes has +shown that the molar teeth of the Orang present an extraordinary and +altogether superfluous amount of attachment in their sockets--the fangs +being not only exceedingly long, and therefore deeply buried in the +jaw-bone, but also curving round one another, so as still further to +strengthen the whole[133]. In the allied genera of anthropoid apes there +is no such abnormal amount of attachment. Now, the question is, of what +conceivable use can it _ever_ have been, either to the existing genus, +or to its parent species, that such an abnormal amount of attachment +should obtain? It certainly is not required to prevent dislocation of +the teeth, seeing that in all allied genera, and even in man himself, +the amount of attachment is already so great that teeth will break +before they can be drawn by anything short of a dentist's forceps. +Therefore I conclude that this peculiarity in the dentition of the genus +must have arisen in its parent species by way of what Darwin calls a +"fluctuating variation," without utilitarian significance. And I adduce +it in the present connexion because the peculiarity is one which is +equally unamenable to a utilitarian explanation, whether it happens to +occur as a generic or a specific character. + + [133] _A Manual of Dental Anatomy_, p. 455. + +Numberless similar cases might be quoted; but probably enough has now +been said to prove the inconsistency of the distinction which our +opponents draw between specific and all higher characters in respect of +utility. In point of fact, a very little thought is enough to show that +no such distinction admits of being drawn; and, therefore, that any one +who maintains the doctrine of utility as universal in the case of +specific characters, must in consistency hold to the same doctrine in +the case of generic and all higher characters. And the fact that our +opponents are unable to do this becomes a virtual confession on their +part of the futility of the generalization which they have +propounded[134]. + + [134] It may be observed that this distinction was not propounded by + Mr. Wallace--nor, so far as I am aware, by anybody else--until + he joined issue with me on the subject of specific characters. + Whether he has always held this important distinction between + specific and generic characters, I know not; but, as + originally enunciated, his doctrine of utility as universal + was subject to no such limitation: it was stated + unconditionally, as applying to all taxonomic divisions + indifferently. The words have already been quoted on page 180; + and, if the reader will turn to them, he may further observe + that, prior to our discussion, Mr. Wallace made no allowance + for the principle of correlation, which, as we have seen, + furnishes so convenient a loop-hole of escape in cases where + even the argument from our ignorance of possible utility + appears absurd. In his latest work, however, he is much less + sweeping in his statements. He limits his doctrine to the case + of "specific characters" alone, and even with regard to them + makes unlimited drafts upon the principle of correlation. + +On what then do Mr. Wallace and his followers rely for their great +distinction between specific and all other characters in respect of +utility? This is the final and fundamental question which I must leave +these naturalists themselves to answer; for my whole contention is, that +it is unanswerable. But although I am satisfied that they have nothing +on which to base their generalization, it seems worth while to conclude +by showing yet one further point. And this is, that these naturalists +themselves, as soon as they quit merely abstract assertions and come to +deal with actual facts, contradict their own generalization. It is worth +while to show this by means of a few quotations, that we may perceive +how impossible it is for them to sustain their generalization in the +domain of fact. + +As it is desirable to be brief, I will confine myself to quoting from +Mr. Wallace. + + "Colour may be looked upon as a necessary result of the highly + complex chemical constitution of animal tissues and fluids. The + blood, the bile, the bones, the fat, and other tissues have + characteristic, and often brilliant colours, which we cannot + suppose to have been determined for any special purpose as colours, + since they are usually concealed. The external organs and + integuments, would, by the same general laws, naturally give rise + to a greater variety of colour[135]." + + [135] _Darwinism_, p. 297. + +Surely comment is needless. Have the colour of external organs and +integuments nothing to do with the determining of specific distinctions +by systematists? Or, may we not rather ask, are there any other +"characters" which have had more to do with their delineation of animal +species? Therefore, if "the external organs and integuments naturally +give rise to a greater variety of colours," for non-utilitarian reasons, +than is the case with internal organs and tissues; while even the latter +present, for similarly non-utilitarian reasons, such variety and +intensity of colours as they do; must it not follow that, on the ground +of the "Laws of Growth" alone, Mr. Wallace has conceded the entire case +as regards "a large proportional number of specific characters" being +non-adaptive--"spontaneous" in their occurrence, and "meaningless" in +their persistence? + +Once more:-- + + "The enormously lengthened plumes of the bird of paradise and of + the peacock, can, however, have no such use [i.e. for purposes of + defence], but must be rather injurious than beneficial in the + birds' ordinary life. The fact that they have been developed to so + great an extent in a few species is an indication of such perfect + adaptation to the conditions of existence, such complete success in + the battle for life, that there is, in the adult male at all + events, a surplus of strength, vitality, and growth-power, which is + able to expend itself in this way without injury. That such is the + case is shown by the great abundance of most of the species which + possess these wonderful superfluities of plumage.... Why, in allied + species, the development of accessory plumes has taken different + forms, we are unable to say, except that it may be due to that + individual variability which has served as a starting-point for so + much of what seems to us strange in form, or fantastic in colour, + both in the animal and vegetable world[136]." + + [136] _Darwinism_, pp. 292-3. + +Here, again, one need only ask, How can such statements be reconciled +with the great dogma, "which is indeed a necessary deduction from the +theory of Natural Selection, namely, that none of the definite facts of +organic nature, no special organ, no characteristic form or marking can +exist, but which must now be, or once have been, _useful_"? Can it be +said that the plumes of a bird of paradise present "no characteristic +form," or the tail of a peacock "no characteristic marking"? Can it be +held that all the "fantastic colours," which Darwin attributes to sexual +selection, and all the "strange forms" in the vegetable world which +present no conceivable reference to adaptation, are to be ascribed to +"individual variability" without reference to utility, while at the same +time it is held, "as a necessary deduction from the theory of Natural +Selection," that _all_ specific characters must be "_useful_"? Or must +we not conclude that we have here a contradiction as direct as a +contradiction can well be[137]? + + [137] Since the above was written both Mr. Gulick and Professor + Lloyd Morgan have independently noticed the contradiction. + +Nor is it any more possible to reconcile these contradictory statements +by an indefinite extension of the term "correlation," than we found it +to be in the cases previously quoted. It might indeed be logically +possible, howsoever biologically absurd, to attribute the tail of a +peacock--with all its elaboration of structure and pattern of colour, +with all the drain that its large size and weight makes upon the vital +resources of the bird, with all the increased danger to which it exposes +the bird by rendering it more conspicuous, more easy of capture, &c.--to +correlation with some useful character peculiar to peacocks. But to say +that it is due to correlation with general "vitality," is merely to +discharge the doctrine of correlation of any assignable meaning. +Vitality, or "perfect adaptation to the conditions of existence," is +obviously a prime condition to the occurrence of a peacock's tail, as it +is to the occurrence of a peacock itself; but this is quite a different +thing from saying that the specific characters which are presented by a +peacock's tail, although useless in themselves, are correlated with some +other and useful specific characters of the same bird--as we saw in a +previous chapter with reference to secondary sexual characters in +general. Therefore, when Mr. Wallace comes to the obvious question why +it is that even in "allied species," which must be in equally "perfect +adaptation to the conditions of existence," there are no such "wonderful +superfluities of plumage," he falls back--as he previously fell back--on +whatever unknown _causes_ it may have been which produced the peacock's +tail, when the primary _condition_ to their operation has been furnished +by "complete success in the battle for life." + +I have quoted the above passages, not so much for the sake of exposing +fundamental inconsistencies on the part of an adversary, as for the sake +of observing that they constitute a much truer exposition of "Darwinism" +than do the contradictory views expressed in some other parts of the +work bearing that title. For even if characters of so much size and +elaboration as the tail of a peacock, the plumes of a bird of paradise +&c., are admitted to be due to non-utilitarian causes, much more must +innumerable other characters of incomparably less size and elaboration +be mere "superfluities." Without being actually deleterious, "a large +proportional number of specific characters," whose utility is not +apparent, must _a fortiori_ have been due to "individual variation," to +"general laws which determine the production" of such characters--or, in +short, to some causes other than natural selection. And this, I say, is +a doctrine much more in harmony with "Darwinism" than is the +contradictory doctrine which I am endeavouring to resist. + +But once again, and still more generally, after saying of "the delicate +tints of spring foliage, and the intense hues of autumn," that "as +colours they are unadaptive, and appear to have no more relation to the +well-being of plants themselves than do the colours of gems and +minerals," Mr. Wallace proceeds thus:-- + + "We may also include in the same category those algae and fungi + which have bright colours--the red snow of the Arctic regions, the + red, green, or purple seaweeds, the brilliant scarlet, yellow, + white or black agarics, and other fungi. All these colours are + probably the direct results of chemical composition or molecular + structure, and being thus normal products of the vegetable + organism, need no special explanation from our present point of + view; and the same remark will apply to the varied tints of the + bark of trunks, branches and twigs, which are often of various + shades of brown and green, or even vivid reds and yellows[138]." + + [138] _Darwinism_, p. 302. + +Here, as Mr. Gulick has already observed, "Mr. Wallace seems to admit +that instead of useless specific characters being unknown, they are so +common and so easily explained by 'the chemical constitution of the +organism' that they claim no special attention[139]." And whatever +answer Mr. Wallace may make to this criticism, I do not see how he is to +meet the point at present before us--namely, that, upon his own showing, +there are in nature numberless instances of "characters which are +useless without being hurtful," and which nevertheless present absolute +"constancy." If, in order to explain the contradiction, he should fall +back upon the principle of correlation, the case would not be in any way +improved. For, here again, if the term correlation were extended so as +to include "the chemical constitution or the molecular structure of the +organism," it would thereby be extended so as to discharge all Darwinian +significance from the term. + + [139] _American Journal of Science_, Vol. XL. art. I. on _The + Inconsistencies of Utilitarianism as the Exclusive Theory of + Organic Evolution_. + + +_Summary._ + +I will conclude this discussion of the Utility question by +recapitulating the main points in an order somewhat different from that +in which they have been presented in the foregoing chapters. Such a +variation may render their mutual connexions more apparent. But it is +only to the main points that allusion will here be made, and, in order +the better to show their independent character, I will separately number +them. + + * * * * * + +1. The doctrine of utility as universal, whether with respect to species +only or likewise with respect to specific characters, is confessedly an +_a priori_ doctrine, deduced by way of general reasoning from the theory +of natural selection. + +2. Being thus founded exclusively on grounds of deduction, the doctrine +cannot be combated by any appeal to facts. For this question is not one +of fact: it is a question of reasoning. The treatment of our subject +matter is logical: not biological. + +3. The doctrine is both universal and absolute. According to one form of +it _all_ species, and according to another form of it _all_ specific +characters, must _necessarily_ be due to the principle of utility. + +4. The doctrine in both its forms is deduced from a definition of the +theory of natural selection as a theory, and the sole theory, of the +origin of _species_; but, as Professor Huxley has already shown, it does +not really follow, even from this definition, that all specific +_characters_ must be "necessarily useful." Hence the two forms of the +doctrine, although coincident with regard to species, are at variance +with one another in respect of specific characters. Thus far, of course, +I agree with Professor Huxley; but if I have been successful in showing +that the above definition of the theory of natural selection is +logically fallacious, it follows that the doctrine in both its forms is +radically erroneous. The theory of natural selection is not, accurately +speaking, a theory of the origin of species: it is a theory of the +origin and cumulative development of adaptations, to whatever order of +taxonomic division these may happen to belong. Thus the premisses of the +deduction which we are considering collapse: the principle of utility is +shown not to have any other or further reference to species, or to +specific characters, than it has to fixed varieties, genera, families, +&c., or to the characters severally distinctive of each. + +5. But, quitting all such antecedent considerations, we next proceeded +to examine the doctrine _a posteriori_, taking the arguments which have +been advanced in favour of the doctrine, other than those which rest +upon the fallacious definition. These arguments, as presented by Mr. +Wallace, are two in number. + +First, it is represented that natural selection must occupy the whole +field, because no other principle of change can be allowed to operate in +the presence of natural selection. Now I fully agree that this statement +holds as regards any principle of change which is deleterious, but I +cannot agree that it does so as regards any such principle which is +merely neutral. No reason has ever been shown why natural selection +should interfere with "indifferent" characters--to adopt Professor +Huxley's term--supposing such to have been produced by any of the +agencies which we shall presently have to name. Therefore this +argument--or rather assertion--goes for nothing. + +Mr. Wallace's second argument is, that utility is the only principle +which can endow specific characters with their characteristic stability. +But this again is mere assertion. Moreover, it is assertion opposed +alike to common sense and to observable fact. It is opposed to common +sense, because it is obvious that any other principle would equally +confer stability on characters due to it, provided that its action is +constant, as Darwin expressly held. Again, this argument is opposed to +fact, because we know of thousands of cases where peculiar characters +are stable, which, nevertheless, cannot possibly be due to natural +selection. Of such are the Porto Santo rabbits, the niata cattle, the +ducks in St. James' Park, turkeys, dogs, horses, &c., and, in the case +of plants, wheat, cabbage, maize, &c., as well as all the hosts of +climatic varieties, both of animals and plants, in a state of nature. +Indeed, on taking a wide survey of the facts, we do not find that the +principle of utility is any better able to confer stability of character +than are many other principles, both known and unknown. Nay, it is +positively less able to do so than are some of these other principles. +Darwin gives two very probable reasons for this fact; but I need not +quote them a second time. It is enough to have seen that this argument +from stability or constancy is no less worthless than the previous one. +Yet these are the only two arguments of a corroborative kind which Mr. +Wallace adduces whereby to sustain his "necessary deduction." + +6. At this point, therefore, it may well seem that we need not have +troubled ourselves any further with a generalization which does not +appear to have anything to support it. And to this view of the case I +should myself agree, were it not that many naturalists now entertain the +doctrine as an essential article of their Darwinian creed. Hence, I +proceeded to adduce considerations _per contra_. + +Seeing that the doctrine in question can only rest on the assumption +that there is no cause other than natural selection which is capable of +originating any single species--if not even so much as any single +specific character--I began by examining this assumption. It was shown +first that, on merely antecedent grounds, the assumption is "infinitely +precarious." There is absolutely no justification for the statement that +in all the varied and complex processes of organic nature natural +selection is the only possible cause of specific change. But, apart +altogether from this _a priori_ refutation of the dogma, our analysis +went on to show that, in point of actual fact, there are not a few +well-known causes of high generality, which, while having no connexion +with the principle of utility, are demonstrably capable of originating +species and specific characters--if by "species" and "specific +characters" we are to understand organic types which are ranked as +species, and characters which are described as diagnostic of species. +Such causes I grouped under five different headings, viz. Climate, Food, +Sexual Selection, Isolation, and Laws of Growth. Sexual Selection and +Isolation are, indeed, repudiated by Mr. Wallace; but, in common I +believe with all biologists, he accepts the other three groups of causes +as fully adequate to produce such kinds and degrees of modification as +are taken to constitute specific distinction. And this is amply +sufficient for our present purposes. Besides, under the head of Sexual +Selection, it does not signify in the present connexion whether or not +we accept Darwin's theory on this subject. For, in any case, the facts +of secondary sexual characters are indisputable: these characters are, +for the most part, specific characters: and they cannot be explained by +the principle of utility. Even Mr. Wallace does not attempt to do so; +and the explanation which he does give is clearly incompatible with his +doctrine touching the necessarily life-serving value of all specific +characters. Lastly, the same has to be said of the Laws of Growth. For +we have just seen that on the grounds of this principle likewise Mr. +Wallace abandons the doctrine in question. As regards Isolation, much +more remains to be said in the ensuing portion of this work, while, as +regards Climatic Variation, there are literally innumerable cases where +changes of specific type are known to have been caused by this means. + +7. To the latter class of cases, however, it will be objected that these +changes of specific type, although no doubt sufficiently "stable" so +long as the changed conditions remain constant, are found by experiment +not to be hereditary; and this clearly makes all the difference between +a true specific change and a merely fictitious appearance of it. + +Well, in the first place, this objection can have reference only to the +first two of the five principles above stated. It can have no reference +to the last three, because of these heredity constitutes the very +foundation. This consideration ought to be borne in mind throughout. But +now, in the second place, even as regards changes produced by climate +and food, the reply is nugatory. And this for three reasons, as follows. + +(_a_) No one is thus far entitled to conclude against the possible +transmission of acquired characters; and, so long as there is even so +much as a possibility of climatic (or any other admittedly +non-utilitarian) variations becoming in this way hereditary, the reply +before us merely begs the question. + +(_b_) Even supposing, for the sake of argument, that acquired characters +can never in any case become congenital, there remains the strong +probability--sanctioned as such even by Weismann--that changed +conditions of life may not unfrequently act upon the material of +heredity itself, thus giving rise to specific changes which are from +the first congenital, though not utilitarian. Indeed, there are not a +few facts (Hoffmann's plants, Weismann's butterflies, &c.), which can +only be explained either in this way, or as above (_a_). And in the +present connexion it is immaterial which of these alternative +explanations we choose to adopt, seeing that they equally refute our +opponents' objection. And not only do these considerations--(_a_) and +(_b_)--refute this particular objection; they overturn on new and +independent grounds the whole of our opponents' generalization. For the +generalization is, that the principle of utility, acting through natural +selection, is "necessarily" the sole principle which can be concerned in +hereditary changes of specific type. But here we perceive both a +possibility (_a_) and a probability (_b_), if not indeed a certainty, +that quite other principles have been largely concerned in the +production of such changes. + +(_c_) Altogether apart from these considerations, there remains a much +more important one. For the objection that fixed--or "stable"--climatic +varieties differ from true species in not being subject to heredity, +raises the question--What are we to understand by a "species"? This +question, which was thus far purposely left in abeyance, had now to be +dealt with seriously. For it would clearly be irrational in our +opponents to make this highly important generalization with regard to +species and specific characters, unless they are prepared to tell us +what they mean by species, and therefore by characters as specific. In +as far as there is any ambiguity on this point it makes entirely for +our side in the debate, because even any small degree of uncertainty +with regard to it would render the generalization in question +proportionally unsound. Yet it is notorious that no word in existence is +more vague, or more impossible to define, than the word "species." The +very same men who at one time pronounce their great generalization with +regard to species, at another time asseverate that "a species is not a +definite entity," but a merely abstract term, serving to denote this +that and the other organic type, which this that and the other +systematist regards as deserving such a title. Moreover it is +acknowledged that systematists differ among themselves to a wide extent +as to the kinds and degrees of peculiarity which entitle a given form to +a specific rank. Even in the same department of systematic work much +depends on merely individual taste, while in different departments +widely different standards of delimination are in vogue. Hence, our +_reductio ad absurdum_ consists in this--that whether a given form is to +be regarded as necessarily due to natural selection, and whether all its +distinctive characters are to be regarded as necessarily utilitarian +characters, will often depend on whether it has been described by +naturalist A or by naturalist B. There is no one criterion--there is not +even any one set of criteria--agreed upon by naturalists for the +construction of specific types. In particular, as regards the principle +of heredity, it is not known of one named species in twenty--probably +not in a hundred--whether its diagnostic characters are hereditary +characters; while, on the other hand, even in cases where experiment has +proved "constant varieties" to be hereditary--and even also +cross-sterile with allied varieties--it is only some three or four +living botanists who for these reasons advocate the elevation of such +varieties to the rank of species. In short, as we are not engaged on any +abstract question touching the principles on which species ought to have +been constituted by their makers, but upon the actual manner in which +they have been, the criterion of heredity must needs be disregarded in +the present discussion, as it has been in the work of systematists. And +the result of this is, that any objection to our introducing the facts +of climatic variation in the present discussion is excluded. In +particular, so far as any question of heredity is concerned, all these +facts are as assuredly as they are cogently relevant. It is perfectly +certain that there is "a large proportional number" of named +species--particularly of plants--which further investigation would +resolve into climatic varieties. With the advance of knowledge, "bad +species" are always increasing at the expense of "good species," so that +we are now justified in concluding with Kerner, Haeckel, and other +naturalists best qualified to speak on this subject, that if we could +know as much about the past history and present relations of the +remaining good species as we do about the bad, all the former, without +exception, would become resolved into the latter. In point of fact, and +apart altogether from the inductive experience on which this conclusion +is based, the conclusion follows "as a necessary deduction" from the +general theory of descent. For this theory essentially consists in +supposing either the past or the present existence of intermediate +varietal forms in all cases, with the consequence that "good species" +serve merely to mark _lacunae_ in our knowledge of what is everywhere a +finely graduated process of transmutation. Hence, if we place this +unquestionably "necessary deduction" from the general theory of descent +side by side with the alleged "necessary deduction" from the theory of +natural selection, we cannot avoid the following absurdity--Whether or +not a given form is to be regarded as necessarily due to natural +selection, and all its characters necessarily utilitarian, is to be +determined, and determined solely, by the mere accident of our having +found, or not having found, either in a living or in a fossil state, its +varietal ancestry. + +8. But this leads us to consider the final and crowning incongruities +which have been dealt with in the present chapter. For here we have +seen, not only that our opponents thus draw a hard and fast line between +"varieties" and "species" in regard to "necessary origin" and "necessary +utility," but that they further draw a similar line between "species" +and "genera" in the same respects. Yet, in accordance with the general +theory of evolution, it is plainly as impossible to draw any such line +in the one case as it is to do so in the other. Just as fixed varieties +are what Darwin called "incipient species," so are species incipient +genera, genera incipient families, and so on. Evolutionists must believe +that the process of evolution is everywhere the same. Nevertheless, +while admitting all this, the school of Huxley contradicts itself by +alleging some unintelligible exception in the case of "species," while +the school of Wallace presses this exception so as to embrace "specific +characters." Indeed Mr. Wallace, while maintaining that all specific +characters must necessarily be useful, maintains at the same time that +any number of varietal characters on the one hand, and a good half of +generic characters on the other, are probably useless. Thus he +contradicts his argument from the "constancy of specific characters" +(seeing that generic characters are still more constant), as later on we +saw that he contradicts his deductive generalization touching their +necessary utility, by giving a non-utilitarian explanation of whole +multitudes of specific characters. I need not, however, again go over +the ground so recently traversed; but will conclude by once more +recurring to the only explanation which I have been able to devise of +the otherwise inexplicable fact, that in regard to this subject so many +naturalists still continue to entangle themselves in the meshes of +absurdity and contradiction. + + * * * * * + +The only conceivable explanation is, that these naturalists have not yet +wholly divested themselves of the special creation theory. Although +professing to have discarded the belief that "species" are "definite +entities," differing in kind from "varieties" on the one hand and from +"genera" on the other, these writers are still imbued with a vague +survival of that belief. They well know it to belong to the very essence +of their new theory that "species" are but "pronounced varieties," or, +should we prefer it, "incipient genera"; but still they cannot +altogether escape the pre-Darwinian conception of species as organic +units, whose single mode of origin need not extend to other taxonomic +groups, and whose characters therefore present some exceptional +significance to the scientific naturalist. So to speak, such divinity +doth still hedge a species, that even in the very act of declaring it +but an idol of their own creation, these naturalists bow before their +fetish as something that is unique--differing alike in its origin and in +its characters from the varieties beneath and the genera above. The +consequence is that they have endeavoured to reconcile these +incompatible ideas by substituting the principle of natural selection +for that of super-natural creation, where the particular case of +"species" is concerned. In this way, it vaguely seems to them, they are +able to save the doctrine of some one mode of origin as appertaining to +species, which need not "necessarily" appertain to any other taxonomic +division. All other such divisions they regard, with their pre-Darwinian +forefathers, as merely artificial constructions; but, likewise with +these forefathers, they look upon species as natural divisions, proved +to be such by a single and necessary mode of origin. Hence, Mr. Wallace +expressly defines a species with reference to this single and necessary +mode of origin (_see_ above, p. 235), although he must be well aware +that there is no better, or more frequent, proof of it in the case of +species, than there is in that of somewhat less pronounced types on the +one hand (fixed varieties), or of more pronounced types on the other +(genera, families, &c.). Hence, also, the theory of natural selection is +defined as _par excellence_ a theory of the origin of species; it is +taken as applying to the particular case of the origin of species in a +peculiarly stringent manner, or in a manner which does not apply to the +origin of any other groups. And I believe that an important accessory +reason of the continuance of this view for more than thirty years after +the publication of the _Origin of Species by means of Natural +Selection_, is to be found in the title of that work. "Natural +Selection" has thus become verbally associated with "Origin of Species," +till it is thoughtlessly felt that, in some way or another, natural +selection must have a peculiar reference to those artificially +delineated forms which stand anywhere between a fixed variety and a +so-called genus. This verbal association has no doubt had the effect of +still further preserving the traditional halo of mystery which clings to +the idea of a "species." Hence it comes that the title which Darwin +chose--and, looking to the circumstances of the time, wisely chose--for +his great work, has subsequently had the effect of fostering the very +idea which it was the object of that work to dissipate, namely, that +species are peculiar entities, which differ more or less in origin or +kind from all other taxonomic groups. The full title of this work +is--_The Origin of Species by means of Natural Selection: or the +Preservation of Favoured Races in the Struggle for Life_. Now, supposing +that instead of this its author had chosen some such title as the +following:--_The Origin of Organic Types by means of Adaptive Evolution: +or Survival of the Fittest Forms in the Struggle for Life_. Of course +this would have been a bad substitute from various points of view; but +could any objection have been urged against it from our present point of +view? I do not see that there could. Yet, if such had been the title, I +have little doubt that we should never have heard of those great +generalizations with regard to species and specific characters, the +futility of which it has been the object of these chapters to expose. + + * * * * * + +In conclusion, it only remains to reiterate that in thus combating what +appears to me plainly erroneous deductions from the theory of natural +selection, I am in no wise combating that theory itself. On the +contrary, I hope that I am rendering it no unimportant service by +endeavouring to relieve it of a parasitic growth--an accretion of false +logic. Regarding as I do the theory of natural selection as, primarily, +a theory of the origin (or cumulative development) of adaptations, I see +in merely non-adaptive characters--be they "specific" or other--a +comparatively insignificant class of phenomena, which may be due to a +great variety of incidental causes, without any further reference to the +master-principle of natural selection than that in the presence of this +principle none of these non-adaptive characters can be actively +deleterious. But that there may be "any number of indifferent +characters" it is no part of the theory of natural selection to deny; +and all attempts to foist upon it _a priori_ "deductions" opposed alike +to the facts of nature and to the logic of the case, can only act to the +detriment of the great generalization which was expressly guarded from +such fallacies by the ever-careful judgement of Darwin. + + + + +APPENDICES AND NOTES + + + + +APPENDIX I. + +ON PANMIXIA. + + +There are several points of considerable theoretical importance +connected with Panmixia, which were omitted from the text, in order to +avoid distracting attention from the main issue which is there under +consideration. These side issues may now be appropriately presented in +the form in which they were published in _Nature_, March 13, 1890[140]. +After stating, in almost the same words, what has already been said in +Chapter X, this paper proceeds, with the exception of a few verbal +alterations, as follows. + + [140] Vol. xli. p. 438. + + "There is, however, one respect in which Professor Weismann's + statement of the principle of panmixia differs from that which was + considered by Mr. Darwin; and it is this difference of + statement--which amounts to an important difference of theory--that + I now wish to discuss. + + "The difference in question is, that while Professor Weismann + believes the cessation of selection to be capable of inducing + degeneration down to the almost complete disappearance of a + rudimentary organ, I have argued that, _unless assisted by some + other principle_, it can at most only reduce the degenerating organ + to considerably above one-half its original size--or probably not + through so much as one-quarter. The ground of this argument (which + is given in detail in the _Nature_ articles of 1873-1874) is, that + panmixia depends for its action upon fortuitous variations round an + ever-diminishing average--the average thus diminishing because it + is no longer _sustained_ by natural selection. But although no + longer sustained by _natural selection_, it does continue to be + sustained by _heredity_; and therefore, as long as the force of + heredity persists unimpaired, fortuitous variations alone--or + variation which is no longer controlled by natural + selection--cannot reduce the dwindling organ to so much as one-half + of its original size; indeed, as above foreshadowed, the balance + between the positive force of heredity and the negative effects of + promiscuous variability will most likely be arrived at above the + middle line thus indicated. Only if for any reason the force of + heredity begins to fail can the average round which the cessation + of selection works become a progressively diminishing average. In + other words, so long as the original force of heredity as regards + the useless organ remains unimpaired, the mere withdrawal of + selection cannot reduce the organ much below the level of + efficiency above which it was previously _maintained_ by the + _presence_ of selection. If we take this level to be 80 or 90 per + cent. of the original size, cessation of selection will reduce the + organ through the 10 or 20 per cent., and there leave it + fluctuating about this average, unless for any reason the force of + heredity begins to fail--in which case, of course, the average will + progressively fall in proportion to the progressive weakening of + this force. + + "Now, according to my views, the force of heredity under such + circumstances is always bound to fail, and this for two reasons. In + the first place, it must usually happen that when an organ becomes + useless, natural selection as regards that organ will not only + _cease_, but become _reversed_. For the organ is now absorbing + nutriment, causing weight, occupying space, and so on, _uselessly_. + Hence, even if it be not also a source of actual danger, 'economy + of growth' will determine a reversal of selection against an organ + which is now not merely useless, but deleterious. And this + degenerating influence of the reversal of selection will throughout + be assisted by the cessation of selection, which will now be always + acting round a continuously sinking average. Nevertheless, a point + of balance will eventually be reached in this case, just as it was + in the previous case where the cessation of selection was supposed + to be working alone. For, where the reversal of selection has + reduced the diminishing organ to so minute a size that its presence + is no longer a source of detriment to the organism, the cessation + of selection will carry the reduction a small degree further; and + then the organ will remain as a 'rudiment.' And so it will remain + permanently, unless there be some further reason why the still + remaining force of heredity should be abolished. This further (or + second) reason I found in the consideration that, however enduring + we may suppose the force of heredity to be, we cannot suppose that + it is actually everlasting; and, therefore, that we may reasonably + attribute the eventual disappearance of rudimentary organs to the + eventual failure of heredity itself. In support of this view there + is the fact that rudimentary organs, although very persistent, are + not everlasting. That they should be very persistent is what we + should expect, if the hold which heredity has upon them is great in + proportion to the time during which they were originally useful, + and thus firmly stamped upon the organization by natural selection + causing them to be strongly inherited in the first instance. For + example, we might expect that it would be more difficult finally to + eradicate the rudiment of a wing than the rudiment of a feather; + and accordingly we find it a general rule that long-enduring + rudiments are rudiments of organs distinctive of the higher + taxonomic divisions--i.e. of organs which were longest in building + up, and therefore longest sustained in a state of working + efficiency. + + "Thus, upon the whole, my view of the facts of degeneration remains + the same as it was when first published in these columns seventeen + years ago, and may be summarized as follows. + + "The cessation of selection when working alone (as it probably does + during the first centuries of its action upon structures or colours + which do not entail any danger to, or perceptible drain upon, the + nutritive resources of the organism) cannot cause degeneration + below, probably, some 10 to 20 per cent. But if from the first the + cessation of selection has been assisted by the _reversal_ of + selection (on account of the degenerating structure having + originally been of a size sufficient to entail a perceptible drain + on the nutritive resources of the organism, having now become a + source of danger, and so forth), the two principles acting together + will continue to reduce the ever-diminishing structure down to the + point at which its presence is no longer a perceptible disadvantage + to the species. When that point is reached, the reversal of + selection will terminate, and the cessation of selection will not + then be able of itself to reduce the organ through more than at + most a very few further percentages of its original size. But, + after this point has been reached, the now total absence of + selection, either for or against the organ, will sooner or later + entail this further and most important consequence, a failure of + heredity as regards the organ. So long as the organ was of use, its + efficiency was constantly _maintained_ by the _presence_ of + selection--which is merely another way of saying that selection was + constantly maintaining the force of heredity as regards that organ. + But as soon as the organ ceased to be of use, selection ceased to + maintain the force of heredity; and thus, sooner or later, that + force began to waver or fade. Now it is this wavering or fading of + the force of heredity, thus originally due to the cessation of + selection, that in turn co-operates with the still continued + cessation of selection in reducing the structure below the level + where its reduction was left by the actual reversal of selection. + So that from that level downwards the cessation of selection, and + the consequent failing of heredity, act and react in their common + work of causing obsolescence. In the case of newly added + characters, the force of heredity will be less than in that of more + anciently added characters; and thus we can understand the long + endurance of 'vestiges' characteristic of the higher taxonomic + divisions, as compared with those characteristic of the lower. But + in all cases, if time enough be allowed under the cessation of + selection, the force of heredity will eventually fall to zero, when + the hitherto obsolescent structure will finally become obsolete. In + cases of newly added and comparatively trivial characters, with + regard to which reversal of selection is not likely to take place + (e.g. slight differences of colour between allied species), + cessation of selection is likely to be very soon assisted by a + failure in the force of heredity; seeing that such newly added + characters will not be so strongly inherited as are the more + ancient characters distinctive of higher taxonomic groups. + + "Let us now turn to Weismann's view of degeneration. First of all, + he has omitted to perceive that 'panmixia' alone (if unassisted + either by reversed selection or an inherent diminishing of the + force of heredity) cannot reduce a functionless organ to the + condition of a _rudiment_. Therefore he everywhere represents + panmixia (or the mere _cessation_ of selection) as of itself + sufficient to cause degeneration, say from 100 to 5, instead of + from 100 to 90 or 80, which, for the reasons above given, appeared + (and still appears) to me about the most that this principle can + accomplish, so long as the original force of heredity continues + unimpaired. No doubt we have here what must be regarded as a mere + oversight on the part of Professor Weismann; but the oversight is + rendered remarkable by the fact that he _does_ invoke the aid of + reversed selection _in order to explain the final disappearance of + a rudiment_. Yet it is self-evident that the reversal of selection + must be much more active during the initial than during the final + stages of degeneration, seeing that, _ex hypothesi_, the greater + the degree of reduction which has been attained the less must be + the detriment arising from any useless expenditure of nutrition, + &c. + + "And this leads me to a second oversight in Professor Weismann's + statement, which is of more importance than the first. For the + place at which he does invoke the assistance of reversed selection + is exactly the place at which reversed selection must necessarily + have ceased to act. This place, as already explained, is where an + obsolescent organ has become rudimentary, or, as above supposed, + reduced to 5 per cent. of its original size; and the reason why he + invokes the aid of reversed selection at this place is in order to + save his doctrine of 'the stability of germ-plasm.' That the force + of heredity should finally become exhausted if no longer + _maintained_ by the _presence_ of selection, is what Darwin's + theory of perishable gemmules would lead us to expect, while such a + fact would be fatal to Weismann's theory of an imperishable + germ-plasm. Therefore he seeks to explain the eventual failure of + heredity (which is certainly a fact) by supposing that after the + point at which the cessation of selection alone can no longer act + (and which his first oversight has placed some 80 per cent. too + low), the reversal of selection will begin to act directly against + the force of heredity as regards the diminishing organ, until such + direct action of reversed selection will have removed the organ + altogether. Or, in his own words, 'The complete disappearance of a + rudimentary organ can only take place by the operation of natural + selection; this principle will lead to its diminution, inasmuch as + the disappearing structure takes the place and the nutriment of + other useful and important organs.' That is to say, the + rudimentary organ finally disappears, not because the force of + heredity is finally exhausted, but because natural selection has + begun to utilize this force against the continuance of the + organ--always picking out those congenital variations of the organ + which are of smallest size, and thus, by its now _reversed_ action, + _reversing_ the force of heredity as regards the organ. + + "Now the oversight here is in not perceiving that the smaller the + disappearing structure becomes, the less hold must 'this principle' + of reversed selection retain upon it. As above observed, during the + earlier stages of reduction (or while co-operating with the + cessation of selection) the reversal of selection will be at its + _maximum_ of efficiency; and, as the process of diminution + continues, a point must eventually be reached at which the reversal + of selection can no longer act. Take the original mass of a now + obsolescent organ in relation to that of the entire organism of + which it then formed a part to be represented by the ratio 1:100. + For the sake of argument we may assume that the mass of the + organism has throughout remained constant, and that by 'mass' in + both cases is meant capacity for absorbing nutriment, causing + weight, occupying space, and so forth. Now, we may further assume + that when the mass of the organ stood to that of its organism in + the ratio of 1:100, natural selection was strongly reversed with + respect to the organ. But when this ratio fell to 1:1000, the + activity of such reversal must have become enormously diminished, + even if it still continued to exercise any influence at all. For we + must remember, on the one hand, that the reversal of selection can + only act as long as the presence of a diminishing organ continues + to be so injurious that variations in its size are matters of life + and death in the struggle for existence; and, on the other hand, + that natural selection in the case of the diminishing organ does + not have reference to the presence and the absence of the organ, + but only to such variations in its mass as any given generation may + supply. Now, the process of reduction does not end even at 1:1000. + It goes on to 1:10,000, and eventually 1:[infinity]. Consequently, + however great our faith in natural selection may be, a point must + eventually come for all of us at which we can no longer believe + that the reduction of an obsolescent organ is due to reversed + selection. And I cannot doubt that if Professor Weismann had + sufficiently considered the matter, he would not have committed + himself to the statement that 'the complete disappearance of a + rudimentary organ can only take place by the operation of natural + selection.' + + "According to my view, the complete disappearance of a rudimentary + organ can only take place by the _cessation_ of natural selection, + which permits the eventual exhaustion of heredity, when heredity is + thus simply left to itself. During all the earlier stages of + reduction, the cessation of selection was assisted in its work by + the reversal of selection; but when the rudiment became too small + for such assistance any longer to be supplied, the rudiment + persisted in that greatly reduced condition until the force of + heredity with regard to it was eventually worn out. This appears to + me, as it appeared in 1873, the only reasonable conclusion that can + be drawn from the facts. And it is because this conclusion is fatal + to Professor Weismann's doctrine of the permanent 'stability' of + germ-plasm, while quite in accordance with all theories which + belong to the family of pangenesis, that I deem the facts of + degeneration of great importance as tests between these rival + interpretations of the facts of heredity. It is on this account + that I have occupied so much space with the foregoing discussion; + and I shall be glad to ascertain whether any of the followers of + Professor Weismann are able to controvert these views. + + "GEORGE J. ROMANES." + + "P.S.--Since the above article was sent in, Professor Weismann has + published in these columns (February 6) his reply to a criticism by + Professor Vines (October 24, 1889). In this reply he appears to + have considerably modified his views on the theory of degeneration; + for while in his Essays he says (as in the passage above quoted) + that 'the complete disappearance of a rudimentary organ can only + take place by the operation of natural selection'--i.e. only by the + _reversal_ of selection,--in his reply to Professor Vines he says, + 'I believe that I have proved that organs no longer in use become + rudimentary, and must finally disappear, solely by 'panmixia'; not + through the direct action of disuse, but because natural selection + no longer sustains their standard structure'--i.e. solely by the + _cessation_ of selection. Obviously, there is here a flat + contradiction. If Professor Weismann now believes that a + rudimentary organ 'must finally disappear _solely_' through the + _withdrawal_ of selection, he has abandoned his previous belief + that 'the complete disappearance of a rudimentary organ can _only_ + take place by the _operation_ of selection.' And this change of + belief on his part is a matter of the highest importance to his + system of theories as a whole, since it betokens a surrender of his + doctrine of the 'stability' of germ-plasm--or of the virtually + everlasting persistence of the force of heredity, and the + consequent necessity for a reversal of this force itself (by + natural selection placing its premium on _minus_ instead of on + _plus_ variations), in order that a rudimentary organ should + finally disappear. In other words, it now seems he no longer + believes that the force of heredity in one direction (that of + sustaining a rudimentary organ) can only be abolished by the active + influence of natural selection determining this force in the + opposite direction (that of removing a rudimentary organ). It seems + he now believes that the force of heredity, if merely left to + itself by the withdrawal of natural selection altogether, will + sooner or later become exhausted through the mere lapse of time. + This, of course, is my own theory of the matter as originally + published in these columns; but I do not see how it is to be + reconciled with Professor Weismann's doctrine of so high a degree + of stability on the part of germ-plasm, that we must look to the + Protozoa and the Protophyta for the original source of congenital + variations as now exhibited by the Metazoa and Metaphyta. + Nevertheless, and so far as the philosophy of degeneration is + concerned, I shall be very glad if (as it now appears) Professor + Weismann's more recent contemplation has brought his principle of + panmixia into exact coincidence with that of my cessation of + selection." + +Before passing on it may here be noted that, to any one who believes in +the inheritance of acquired characters, there is open yet another +hypothetical cause of degeneration, and one to which the final +disappearance of vestigial organs may be attributed. Roux has shown in +his work on _The Struggle for Existence between Parts of an Organism_ +that the principle of selection must operate in every constituent +tissue, and as between every constituent cell of which an organism is +composed. Now, if an organ falls into disuse, its constituent cells +become worsted in their struggles with other cells in the organism. +Hence, degeneration of the disused organ may progressively increase, +quite independently of any struggle for existence on the part of the +organism as a whole. Consequently, degeneration may proceed without any +reference to the principle of "economized nutrition"; and, if it does +so, and if the effects of its doing so are transmitted from generation +to generation, the disused organ will finally disappear by means of +Roux's principle. + +The long communication above quoted led to a still longer correspondence +in the pages of _Nature_. For Professor Ray Lankester wrote[141] to +impugn the doctrine of panmixia, or cessation of selection, _in toto_, +arguing with much insistence that "cessation of selection must be +supplemented by economy of growth in order to produce the results +attributed to panmixia." In other words, he denied that panmixia alone +can cause degeneration in any degree at all; at most, he said, it can be +but "a condition," or "a state," which occurs when an organ or part +ceases to be useful, and therefore falls under the degenerating +influence of active causes, such as economy of nutrition. Or, in yet +other words, he refused to recognize that any degenerative process can +be due to natural selection as merely withdrawn: only when, besides +being _withdrawn_, natural selection is _reversed_, did he regard a +degenerative process as possible. As a result of the correspondence, +however, he eventually[142] agreed that, if the "birth-mean" of an +organ, in respect either of size or complexity of structure, be lower +than the "selection-mean" while the organ is useful (a fact which he +does not dispute); then, if the organ ceases to be useful, it will +degenerate by the withdrawal of selection alone. Which, of course, is +merely a re-statement of the doctrine of panmixia, or cessation of +selection, in somewhat varied terminology--provided that the birth-mean +be taken over a number of generations, or not only over a few following +the selection-mean of the structure while still in its highest state of +efficiency. For the sake of brevity I will hereafter speak of these "few +following" generations by the term of "first generations." + + [141] _Nature_, vol. xli. p. 486. + + [142] _Ibid._ vol. xlii. p. 52. + +It remains to consider the views of Professor Lloyd Morgan upon the +subject. In my opinion he is the shrewdest, as well as the most logical +critic that we have in the field of Darwinian speculation; therefore, if +possible, I should like to arrive at a full agreement with him upon this +matter. His latest utterance with regard to it is as follows:-- + + "To account for the diminution of organs or structures no longer of + use, apart from any inherited effects of disuse, Mr. Romanes has + invoked the Cessation of Selection; and Mr. Francis Galton has, in + another connexion, summarized the effects of this cessation of + selection in the convenient phrase 'Regression to Mediocrity.' This + is the Panmixia of Professor Weismann and his followers; but the + phrase regression to mediocrity through the cessation of selection + appears to me preferable. It is clear that so long as any organ or + structure is subject to natural selection through elimination, it + is, if not actually undergoing improvement, kept at a high standard + of efficiency through the elimination of all those individuals in + which the organ in question falls below the required standard. But + if, from change in the environment or any other cause, the + character in question ceases to be subject to selection, + elimination no longer takes place, and the high standard will no + longer be maintained. There will be reversion to mediocrity. The + probable amount of this reversion is at present a matter under + discussion[143]." + + [143] _Presidential Address to the Bristol Naturalists' Society_, + 1891. + +So far, then, Professor Lloyd Morgan is in complete agreement with +previous writers upon the subject. He does not doubt that the cessation +of selection must always be a cause of degeneration: the only question +is as to the _potency_ of this cause, or the _amount_ of degeneration +which it is capable of effecting. + +Taking, first, the case of bulk or size of an organ, as distinguished +from its organization or complexity, we have seen that Weismann +represents the cessation of selection--even if working quite alone, or +without any assistance from the reversal of selection--to be capable of +reducing a fully developed organ to the state of a rudiment, or even, if +we take his most recent view, of abolishing the organ _in toto_. + +Professor Lloyd Morgan, on the other hand, does not think that the +cessation of selection alone can cause reduction further than the level +of "mediocrity" in the first generations--or, which is much the same +thing, further than the difference between the "birth-mean" and the +"selection-mean" of the first generations. This amount of reduction he +puts at 5 per cent., as "a very liberal estimate." + +Here, then, we have three estimates of the amount of degeneration which +can be produced by panmixia alone, where mere size or bulk of an organ +is concerned--say, 3 to 5 per cent., 10 to 20 per cent., and 95 per +cent. to 0. At first sight, these differences appear simply ludicrous; +but on seeking for the reasons of them, we find that they are due to +different views touching the manner in which panmixia operates. The +oversights which have led to Weismann's extremely high estimate have +already been stated. The reason of the difference between the extremely +low estimate of Professor Lloyd Morgan, as compared with my own +intermediate one, is, that he supposes the power of panmixia to become +exhausted as soon as the level of mediocrity of the first generations +has become the general level in succeeding generations. In my view, +however, the level of mediocrity is itself a sinking level in +successive generations, with the result that there is no reason why the +reducing power of panmixia should ever become exhausted, save that the +more reduction it effects the greater is the force of heredity which +remains to be overcome, as previously explained. Thus the only question +between Professor Lloyd Morgan and myself is--Does the level of +mediocrity fall in successive generations under the cessation of +selection, or does it remain permanently where it used to be under the +presence of selection? Does the "birth-mean" remain constant throughout +any number of generations, notwithstanding that the sustaining influence +of selection has been withdrawn; or does it progressively sink as a +consequence of such withdrawal? + +In order to answer this question we had better begin by considering now +the case of organization of structure, as distinguished from mere size +of structure. Take any case where a complex organ--such as a compound +eye--has been slowly elaborated by natural selection, and is it not +self-evident that, when natural selection is withdrawn, the complex +structure will deteriorate? In other words, the level of mediocrity, say +in the hundred thousandth generation after the sustaining influence of +natural selection has been withdrawn, will not be so high as it was in +the first generations. For, by hypothesis, there is now no longer any +elimination of unfavourable variations, which may therefore perpetuate +themselves as regards any of the parts of this highly complex mechanism; +so that it is only a matter of time when the mechanism must become +disintegrated. I can scarcely suppose that any one who considers the +subject will question this statement, and therefore I will not say +anything that might be said in the way of substantiating it. But, if the +statement be assented to, it follows that there is no need to look for +any cause of deterioration, further than the withdrawal of selection--or +cessation of the principle which (as we are supposing) had hitherto +been the sole means of maintaining efficient harmony among all the +independently variable parts of the highly complex structure. + +Now, I hold that the same thing is true, though in a lesser degree, as +regards degeneration of size. That there is no difference _in kind_ +between the two cases, Professor Lloyd Morgan implicitly allows; for +what he says is-- + + "In any long-established character, such as wing-power in birds, + brain-development, the eyes of crustacea, &c., no shortcomer in + these respects would have been permitted by natural selection to + transmit his shortcomings for hundreds of generations. All tendency + to such shortcomings would, one would suppose, have been bred out + of the race. If after this long process of selection there still + remains a strong tendency to deterioration, this tendency demands + an explanation[144]." + + [144] _Presidential Address to the Bristol Naturalists' Society_, + 1891. + +Here, then, deterioration as to size of structure (wings of birds), and +deterioration as to complexity of structure (brain and eyes) are +expressly put upon the same footing. Therefore, if in the latter case +the "tendency to deterioration" does not "demand an explanation," beyond +the fact that the hitherto maintaining influence has been withdrawn, +neither is any such further explanation demanded in the former case. +Which is exactly my own view of the matter. It is also Mr. Galton's +view. For although, in the passage formerly quoted, Professor Lloyd +Morgan appears to think that by the phrase "Regression to Mediocrity" +Mr. Galton means to indicate that panmixia can cause degeneration only +as far as the mediocrity level of the first generations, this, in point +of fact, is not what Galton means, nor is it what he says. The phrase in +question occurs "in another connexion," and, indeed, in a different +publication. But where he expressly alludes to the cessation of +selection, this is what he says. The italics are mine. + + "A special cause may be assigned for the effects of use in causing + hereditary _atrophy_ of disused parts. It has already been shown + that all exceptionally developed organs tend to deteriorate: + consequently, those that are not _protected_ by selection will + _dwindle_. The level of muscular efficiency in the wing of a + strongly flying bird [curiously enough, the same case that is + chosen by Professor Lloyd Morgan to illustrate his opposite view], + is like the level of water in the leaky vessel of a Danaid, only + secured to the race by _constant effort_, so to speak. _Let the + effort be relaxed ever so little, and the level immediately + falls[145]._" + + [145] _A Theory of Heredity_, Journal of Anthropological Institute, + 1875. Vol. v. p. 345. + +I take it, then, that the burden of proof lies with Professor Lloyd +Morgan to show why the withdrawal of selection is _not_ sufficient to +account for degeneration any further than the mediocrity-level in the +former presence of selection. Why does "the strong tendency[146] to +deterioration demand an explanation," further than the fact that when +all variations below the average in every generation are allowed to +survive, they must gradually lower the average itself through a series +of generations? To answer that any such tendency "would have been bred +out of the race" by the previous action of selection, is to suppose that +the function of selection is at an end when once it has built up a +structure to the highest point of working efficiency,--that the presence +of selection is no longer required to _maintain_ the structure at that +point. But it is enough to ask in reply--Why, under the cessation of +selection, does _complexity_ of structure degenerate so much more +rapidly than _size_ of structure? Why is it, for instance, that "the +eyes of crustacea" in dark caves have entirely disappeared, while their +foot-stalks (when originally present) still remain? Can it be maintained +that "for hundreds of generations" natural selection was more intent on +developing the foot-stalks than the eyes which were mounted upon +them--so that while the latter were left by selection with "a strong +tendency to deterioration," the former have had this tendency "bred out +in the race"[147]? + + [146] No one has supposed that the tendency need be "strong": it has + only to be persistent. + + [147] Of course it must be observed that degeneration of complexity + involves also degeneration of size, so that a more correct + statement of the case would be--Why, under the cessation of + selection, does an organ of extreme complexity degenerate much + more rapidly than one of much less complexity? For example, + under domestication the brains of rabbits and ducks appear to + have been reduced in some cases by as much as 50 per cent. + (Darwin, and Sir J. Crichton Browne.) But if it is possible to + attribute this effect--or part of it--to an artificial + selection of stupid animals, I give in the text an example + occurring under nature. Many other cases, however, might be + given to show the general rule, that under cessation of + selection complexity of structure degenerates more + rapidly--and also more thoroughly--than size of it. This, of + course, is what Mr. Galton and I should expect, seeing that + the more complex a structure the greater are the number of + points for deterioration to invade when the structure is no + longer "protected by selection." (On the other hand, of + course, this fact is opposed to the view that degeneration of + useless structures below the "birth-mean" of the first + generations, is exclusively due to the reversal of selection; + for economy of growth, deleterious effect of weight, and so + forth, ought to affect size of structure _much more_ than + complexity of it.) But I choose the above case, partly because + Professor Lloyd Morgan has himself alluded to "the eyes of + crustacea," and partly because Professor Ray Lankester has + maintained that the loss of these eyes in dark caves is due to + the reversal of selection, as distinguished from the cessation + of it. In view of the above parenthesis it will be seen that + the point is not of much importance in the present connexion; + but it appears to me that cessation of selection must here + have had at least the larger share in the process of atrophy. + For while the economy of nutrition ought to have removed the + relatively large _foot-stalks_ as rapidly as the _eyes_, I + cannot see that there is any advantage, other than the economy + of nutrition, to be gained by the rapid loss of hard-coated + _eyes_, even though they have ceased to be of use. + +To sum up. There is now no question in any quarter touching the fact +that panmixia, or the cessation of selection, is a true cause of +degeneration. The only question is as to the amount of degeneration +which it is able to effect when not assisted by the reversal of +selection, or any other cause of degeneration. Moreover, even with +regard to this question of amount, there is no doubt on any side that +panmixia alone causes degeneration _more rapidly_ where it has to do +with complexity of organization, than it does where it is concerned with +a mere reduction of mass. + +The question as to the amount of degeneration that is caused by the +cessation of selection alone is without any practical importance where +species in a state of nature are concerned, because here the cessation +of selection is probably always associated more or less with the +reversal of it; and it is as impossible as it is immaterial to determine +the relative shares which these two co-operating principles take in +bringing about the observed results. But where organisms in a state of +domestication are concerned, the importance of the question before us is +very great. For if the cessation of selection alone is capable of +reducing an organ through 10 or 12 per cent. of its original size, +nearly all the direct evidence on which Darwin relied in favour of +use-inheritance is destroyed. On the other hand, if reduction through 5 +per cent. be deemed a "very liberal estimate" of what this principle can +accomplish, the whole body of Darwin's direct evidence remains as he +left it. I have now given my reasons for rejecting this lower estimate +on the one band, and what seems to me the extravagant estimate of +Weismann on the other. But my own intermediate estimate is enough to +destroy the apparent proof of use-inheritance that was given by Darwin. +Therefore it remains for those who deny Lamarckian principles, either to +accept some such estimate, or else to acknowledge the incompatibility of +any lower one with the opinion that there is no evidence in favour of +these principles. + + + + +APPENDIX II. + +ON CHARACTERS AS ADAPTIVE AND SPECIFIC. + + +It is the object of this Appendix to state, more fully than in the text, +the opinions with regard to this subject which have been published by +the two highest authorities on the theory of natural selection--Darwin +and Professor Huxley. I will take first the opinion of Professor Huxley, +quoted _in extenso_, and then consider it somewhat more carefully than +seemed necessary in the text. + +As far as I am aware, the only occasion on which Professor Huxley has +alluded to the subject in question, is in his obituary notice of Darwin +in the _Proceedings of the Royal Society_, Vol. XLIV, No. 269, p. xviii. +The allusion is to my paper on _Physiological Selection_, in the +_Journal of the Linnaean Society_, Zool. Vol. XIX, pp. 337-411. But it +will be observed that the criticism has no reference to the theory which +it is the object of that paper to set forth. It refers only to my +definition of the theory of natural selection as primarily a theory of +the origin, or cumulative development, of adaptations. This criticism, +together with my answer thereto at the time, is conveyed in the +following words. + + "Every variety which is selected into a species is favoured and + preserved in consequence of being, in some one or more respects, + better adapted to its surroundings than its rivals. In other words, + every species which exists, exists in virtue of adaptation, and + whatever accounts for that adaptation accounts for the existence of + the species. To say that Darwin has put forward a theory of the + adaptation of species, but not of their origin, is therefore to + misunderstand the first principles of the theory. For, as has been + pointed out, it is a necessary consequence of the theory of + selection that every species must have some one or more structural + or functional peculiarities, in virtue of the advantage conferred + by which it has fought through the crowd of its competitors, and + achieved a certain duration. In this sense, it is true that every + species has been 'originated' by selection." + + Now, in the first place, I have nowhere said that "Darwin has put + forward a theory of the adaptation of species, but not of their + origin." I said, and continue to say, that he has put forward a + theory of _adaptations in general_, and that where such adaptations + appertain to species only (i.e. are peculiar to particular + species), the theory becomes "_also_ a theory of the origin of the + species which present them." The only possible misunderstanding, + therefore, which can here be alleged against me is, that I fail to + perceive it as a "necessary consequence of the theory of selection + that _every_ species _must_ have some one or more structural or + functional _peculiarities_" of an adaptive or utilitarian kind. + Now, if this is a misunderstanding, I must confess to not having + had it removed by Mr. Huxley's exposition. + + The whole criticism is tersely conveyed in the form of two sequent + propositions--namely, "Every species which exists, exists in virtue + of adaptation; and whatever accounts for that adaptation accounts + for the existence of the species." My answer is likewise two-fold. + First, I do not accept the premiss; and next, even if I did, I can + show that the resulting conclusion would not overturn my + definition. Let us consider these two points separately, beginning + with the latter, as the one which may be most briefly disposed of. + + I. Provisionally conceding that "every species which exists, exists + in virtue of adaptation," I maintain that my definition of the + theory of natural selection still holds good. For even on the basis + of this concession, or on the ground of this assumption, the theory + of natural selection is not shown to be "_primarily_" a theory of + the origin of species. It follows, indeed, from the assumption--is, + in fact, part and parcel of the assumption--that all species have + been originated by natural selection; but why? _Only because + natural selection has originated those particular adaptive features + in virtue of which (by the hypothesis) species exist as species._ + It is only in virtue of having created these features that natural + selection has created the species presenting them--just as it has + created genera, families, orders, &c., in virtue of _other_ + adaptive features extending through progressively wider areas of + taxonomic division. Everywhere and equally this principle has been + "primarily" engaged in the evolution of adaptations, and if one + result of its work has been that of enabling the systematist to + trace lines of genetic descent under his divisions of species, + genera, and the rest, such a result is but "secondary" or + "incidental." + + In short, it is "_primarily_" a theory of adaptations _wherever + these occur_, and only becomes "_also_" or "_incidentally_" a + theory of species in cases where adaptations happen to be + restricted in their occurrence to organic types of a certain order + of taxonomic division. + + II. Hitherto, for the sake of argument, I have conceded that, in + the words of my critic, "it is a necessary consequence of the + theory of selection that every species must have some one or more + structural or functional peculiarities" of an adaptive kind. But + now I will endeavour to show that this statement does not "follow + as a necessary consequence" from "the theory of selection." + + Most obviously "it follows" from the theory of selection that + "every variety which is selected into a species is favoured and + preserved in consequence of being, in some one or more respects, + better adapted to its surroundings than its rivals." This, in fact, + is no more than a re-statement of the theory itself. But it does + _not_ follow that "every species which exists, exists in virtue of + adaptation" _peculiar to that species_; i.e. that every species + which exists, exists _in virtue of having been "selected_." This + may or may not be true as a matter of fact: as a matter of logic, + the inference is not deducible from the selection theory. Every + variety which is "_selected into_" a species must, indeed, present + some such peculiar advantage; but this is by no means equivalent to + saying, "in other words," that every variety which _becomes_ a + species must do so. For the latter statement imports a completely + new assumption--namely, that every variety which _becomes_ a + species must do so because it has been "_selected into_" a species. + In short, what we are here told is, that if we believe the + selection principle to have given origin to some species, we must + further believe, "as a necessary consequence," that it has given + origin to all species. + +The above reply, which is here quoted _verbatim_ from _Nature_, Vol. 38, +p. 616-18, proceeded to show that it does not belong to "the first +principles of the theory of natural selection" to deny that no other +cause than natural selection can possibly be concerned in the origin of +species; and facts were given to prove that such unquestionably has been +the case as regards the origin of "local" or "permanent" _varieties_. +Yet such varieties are what Darwin correctly terms "incipient" species, +or species in process of taking _origin_. Therefore, if Professor +Huxley's criticism is to stand at all, we must accept it "as a necessary +consequence of the theory of selection," that every such _variety_ +"which exists, exists in virtue of adaptation"--a statement which is +_proved_ to be untrue by the particular cases forthwith cited. But as +this point has been dealt with much more fully in the text of the +present treatise, I shall sum up the main points in a few words. + +The criticism is all embodied in two propositions--namely, (_a_) that +the theory of natural selection carries with it, as a "necessary +consequence," the doctrine that survival of the fittest has been the +cause of the origin of _all_ species; and (_b_) that therefore it +amounts to one and the same thing whether we define the theory as a +theory of species or as a theory of adaptations. Now, as a mere matter +of logical statement, it appears to me that both these propositions are +unsound. As regards the first, if we hold with Darwin that other causes +have co-operated with natural selection in the origination of some (i. +e. many) species, it is clearly no part of the theory of natural +selection to assume that none of these causes can ever have acted +independently. In point of fact, as we have seen in the foregoing +chapters, such has probably and frequently been the case under the +influences of isolation, climate, food, sexual selection, and laws of +growth; but I may here adduce some further remarks with regard to yet +another possible cause. If the Lamarckian principles are valid at all, +no reason can be shown why in some cases they may not have been +competent _of themselves_ to induce morphological changes of type by +successive increments, until a transmutation of species is effected by +their action alone--as, indeed, Weismann believes to have been the case +with all the species of Protozoa[148]. That such actually has often been +the case also with numberless species of Metozoa, is the belief of the +neo-Lamarckians; and whether they are right or wrong in holding this +belief, it is equally certain that, _as a matter of logical reasoning_, +they are not compelled by it to profess any _disbelief_ in the agency of +natural selection. They may be mistaken as to the facts, as Darwin in a +lesser degree may have been similarly mistaken; but just as Darwin has +nowhere committed himself to the statement that _all_ species must +_necessarily_ have been originated by natural selection, so these +neo-Lamarckians are perfectly logical in holding that _some_ species may +have been wholly caused by the inheritance of acquired characters, as +_other_ species may have been wholly caused by the natural selection of +congenital characters. In short, unless we begin by assuming (with +Wallace and against Darwin) that there _can be no other cause_ of the +origin of species than that which is furnished by natural selection, we +have no basis for Professor Huxley's statement "that every species has +been originated by selection"; while, if we do set out with this +assumption, we end in a mere tautology. What ought to be done is to +prove the validity of this assumption; but, as Professor Huxley makes +no attempt to do this, his criticism amounts to mere begging of the +question. + + [148] Since the above was written Professor Weismann has transferred + this doctrine from the Protozoa to their ancestors. + +And now, as regards the second point (_b_), even if we grant the +assumption that natural selection is the only possible cause of the +origin of species--or, which is the same thing, that every species has +been originated by natural selection,--is it likewise the same thing +whether we define the theory of natural selection as a theory of species +or as a theory of adaptations? Professor Huxley's criticism endeavours +to show that it is; but a little consideration is enough to show that it +is not. What does follow from the assumption is, that, _so far as +specific characters are concerned_, it is one and the same thing to say +that the theory is a theory of species, and to say that it is a theory +of adaptations. But specific characters are not conterminous with +adaptive characters; for innumerable adaptive characters are not +distinctive of species, but of genera, families, orders, classes, and +sub-kingdoms. Therefore, if it is believed (as, of course, Professor +Huxley believes) that the theory in question explains the evolution of +all adaptive characters, obviously it is not one and the same thing to +define it indifferently as a theory of species or as a theory of +adaptations. + +Now, all this is not merely a matter of logic chopping. On the contrary, +the question whether we are to accept or to reject the deduction that +all species must necessarily have owed their origin to natural +selection, is a question of no small importance to the general theory of +evolution. And our answer to this question must be determined by that +which we give to the ulterior question--Is the theory of natural +selection to be defined as a theory of species, or as a theory of +adaptations? + + * * * * * + +We now pass on to our consideration of Darwin's opinion touching the +question, as stated by himself,--"The doctrine of utility, how far +true?" As I cannot ascertain that Darwin has anywhere expressed an +opinion as to whether natural selection has been necessarily concerned +in the origin of all _species_, the issue here is as to whether he held +this with regard to all _specific characters_. It will be remembered +that while opposing this doctrine as erroneous both in logic and in +fact, I have represented that it is not a doctrine which Darwin +sanctioned; but, on the contrary, that it is one which he expressly +failed to sanction, by recognizing the frequent inutility of specific +characters. Mr. Wallace, on the other hand, alleges that Darwin did +believe in the universal--as distinguished from the general--utility of +such characters. And he adds that he has "looked in vain in Mr. Darwin's +works" for any justification of my statements to the contrary[149]. +Therefore I will endeavour to show that Mr. Wallace's search has not +been a very careful one. + + [149] _Darwinism_, p. 131. He says:--"I have looked in vain in Mr. + Darwin's works for any such acknowledgement" (i.e. "that a + large proportion of specific distinctions must be conceded + useless to the species presenting them"). + +We must remember, however, that it was not until the appearance of my +paper on _Physiological Selection_, four years after Darwin's death, +that the question now in debate was raised. Consequently, he never had +occasion to deal expressly with this particular question--viz. whether +"the doctrine of utility" has any _peculiar_ reference to _specific_ +characters--as he surely would have done had he entertained the +important distinction between specific and all other characters which +Mr. Wallace now alleges that he did entertain. But, be this as it may, +we cannot expect to find in Darwin's writings any express allusion to a +question which had not been raised until 1886. The most we can expect to +find are scattered sentences which prove that the distinction in +question was never so much as present to his mind,--i. e. never occurred +to him as even a possible distinction. + +I will first take the passages which Mr. Wallace himself supplies from +among those which I had previously indicated. + + "But when, from the nature of the organism and of the conditions, + modifications have been induced which are unimportant for the + welfare of the _species_, they may be, and apparently often have + been, transmitted in nearly the same state to numerous, otherwise + modified, descendants[150]." + + [150] _Origin of Species_, p. 175. Italics mine. + +On this passage Mr. Wallace remarks that the last five words "clearly +show that such characters are usually not 'specific,' in the sense that +they are such as distinguish species from one another, but are found in +numerous allied species." But I cannot see that the passage shows +anything of the sort. What to my mind it does show is, (_a_) that Mr. +Darwin repudiated Mr. Wallace's doctrine touching the _necessary_ +utility of _all_ specific characters: (_b_) that he takes for granted +the contrary doctrine touching the inutility of _some_ specific +characters: (_c_) that without in this place alluding to the +proportional number of useless specific characters, he refers their +origin in some cases to "the nature of the organism" (i.e. "spontaneous +variability" due to internal causes), and in other cases to "the +conditions" (i.e. variability induced by external causes): (_d_) that +when established as a specific character by heredity, such a useless +character was held by him not to tend to become obsolete by the +influence of natural selection or any other cause; but, on the contrary, +to be "transmitted in nearly the same state to numerous, otherwise +modified, descendants"--or progeny of the species in genera, families, +&c.: (_e_) and, therefore, that useless characters which are now +distinctive of genera, families, &c., were held by him frequently, if +not usually, to point to uselessness of origin, when first they arose as +merely specific characters. Even the meaning which Mr. Wallace reads +into this passage must imply every one of these points; and therefore I +do not see that he gains much by apparently seeking to add this further +meaning--viz. that in Darwin's opinion there must have been some +unassignable reason preventing the occurrence of useless specific +characters in cases where species are _not_ destined to become the +parents of genera. + +Moreover, any such meaning is out of accordance with the context from +which the passage is taken. For, after a long consideration of the +question of utility, Darwin sums up,--"We thus see that with plants many +morphological changes may be attributed to the laws of growth and the +interaction of parts, _independently of natural selection_." And then he +adds,--"From the fact of the above characters being _unimportant for the +welfare of the species_, any slight variations which occurred in them +_would not have been augmented through natural selection_." Again, still +within the same passage, he says, while alluding to the causes other +than natural selection which lead to changes of specific +characters,--"If the _unknown cause_ were to act almost uniformly for a +length of time, we may infer that the result would be almost uniform; +and in this case _all_ the individuals of the _species_ would be +modified in the same manner." For my own part I do not understand how +Mr. Wallace can have overlooked these various references to _species_, +all of which occur on the very page from which he is quoting. The whole +argument is to show that "many morphological changes may be attributed +to the laws of growth and the inter-action of parts [_plus_ external +conditions of life], independently of natural selection"; that such +non-adaptive changes, when they occur as "specific characters," may, if +the species should afterwards give rise to genera, families, &c., become +distinctive of these higher divisions. But there is nothing here, or in +any other part of Darwin's writings, to countenance the inconsistent +notion which Mr. Wallace appears to entertain,--viz. that species which +present useless characters are more apt to give rise to genera, +families, &c., than are species which do not present such characters. + +The next passage which Mr. Wallace quotes, with his comments thereon, is +as follows. The italics are his. + + "'Thus a large yet undefined extension may safely be given to the + direct and indirect results of natural selection; but I now admit, + after reading the essay of Naegeli on plants, and the remarks by + various authors with respect to animals, more especially those + recently made by Professor Broca, that in the earlier editions of + my Origin of Species I perhaps attributed too much to the action of + natural selection, or the survival of the fittest. I have altered + the fifth edition of the Origin so as to confine my remarks to + adaptive changes of structure; _but I am convinced, from the light + gained during even the last few years, that very many structures + which now appear to be useless, will hereafter be proved to be + useful, and will therefore come within the range of natural + selection_. Nevertheless I did not formerly consider sufficiently + the existence of structures which, as far as we can at present + judge, are neither beneficial nor injurious; and this I believe to + be one of the greatest oversights as yet detected in my work.' + + Now it is to be remarked that neither in these passages nor in any + of the other less distinct expressions of opinion on this question, + does Darwin ever admit that "specific characters"--that is, the + particular characters which serve to distinguish one species from + another--are ever useless, much less that "a large proportion of + them" are so, as Mr. Romanes makes him "freely acknowledge." On the + other hand, in the passage which I have italicised he strongly + expresses his view that much of what we suppose to be useless is + due to our ignorance; and as I hold myself that, as regards many of + the supposed useless characters, this is the true explanation, it + may be well to give a brief sketch of the progress of knowledge in + transferring characters from the one category to the other[151]." + + [151] _Darwinism_, p. 132. + +It is needless to continue this quotation, because of course no one is +disputing that an enormous number of specific characters whose utility +is unknown are nevertheless useful, and therefore due to natural +selection. In other words, the question is not--Are there not many +useful specific characters whose utility is unknown? but--Does it follow +from the theory of natural selection that all specific characters must +necessarily be useful? Well, it appears to me that without going further +than the above passage, which Mr. Wallace has quoted, we can see clearly +enough what was Darwin's opinion upon the subject. He did not believe +that it followed _deductively_ from his theory that all specific +characters must necessarily be useful; and therefore he regarded it as a +question of _fact_--to be determined by induction as distinguished from +deduction--in what proportional number of cases they are so. Moreover he +gives it as his more matured opinion, that, "as far as we can at present +judge" (i.e. from the present state of observation upon the subject: if, +with Mr. Wallace, his judgement were _a priori_, why this +qualification?), he had not previously sufficiently considered the +existence of non-adaptive characters--and this he ended by believing was +one of the greatest oversights as yet detected in his work. To me it has +always seemed that this passage is one of the greatest exhibitions of +candour, combined with solidity of judgement, that is to be met with +even in the writings of Darwin. There is no talk about any deductive +"necessity"; but a perfect readiness to allow that causes other than +natural selection may have been at work in evoking non-adaptive +characters, so that the fifth edition of the _Origin of Species_ was +altered in order to confine the theory of natural selection to "adaptive +changes"--i.e. to constitute it, as I have said in other words, "a +theory of the origin, or cumulative development, of _adaptations_." + +If to this it be said that in the above passage there is no special +mention of _species_, the quibble would admit of a three-fold reply. In +the first place, the quibble in question had never been raised. As +already stated, it is only since the appearance of my own paper on +_Physiological Selection_ that anybody ever thought of drawing a +distinction between species and genera, such that while all specific +characters must be held necessarily useful, no such necessity extends to +generic characters. In the second place, that Darwin must have had +specific characters (as well as generic) in his mind when writing the +above passage, is rendered unquestionable by the fact that many of the +instances of inutility adduced by Naegeli and Broca have reference to +specific characters. Lastly, as shown in the passages previously quoted +from the sixth edition of the _Origin of Species_, Darwin attributed the +origin of useless generic characters to useless specific characters; so +that Mr. Wallace really gains nothing by his remark that specific +characters are not specially mentioned in the present passage. + +Once more:-- + + "Darwin's latest expression of opinion on this question is + interesting, since it shows he was inclined to return to his + earlier view of the general, or universal, utility of specific + characters[152]." + + [152] _Darwinism_, p. 142. + +This "latest expression of opinion," as I shall immediately prove, shows +nothing of the kind--being, in fact, a mere re-statement of the opinion +everywhere and at all times expressed by Darwin, touching the caution +that must be observed in deciding, _with respect to individual cases_, +whether an apparently useless specific character is to be regarded as +really useless. Moreover, at no time and in no place did Darwin +entertain any "view of the general, or universal, utility of specific +characters." But the point now is, that if (as was the case) Darwin +"inclined" to depart more and more from his earlier view of the highly +_general_ utility of specific characters; and if (as was not the case) +he ended by showing an inclination "_to return_" to this earlier view; +what becomes of the whole of Mr. Wallace's contention against which +this Appendix is directed, namely, _that Darwin never entertained any +other view than that of the "general, or universal, utility of specific +characters_"? + +The "latest expression of opinion" which Mr. Wallace quotes, occurs in a +letter written to Professor Semper in 1878. It is as follows:-- + + "As our knowledge advances, very slight differences, considered by + systematists as of no importance in structure, are continually + found to be functionally important; and I have been especially + struck with this fact in the case of plants, to which my + observations have of late years been confined. Therefore it seems + to me rather rash to consider the slight differences between + representative species, for instance those inhabiting the different + islands of the same archipelago, as of no functional importance, + and as not in any way due to natural selection[153]." + + [153] _Life and Letters_, vol. iii. p. 161. + +Now, with regard to this passage it is to be observed, as already +remarked, that it refers to the formation of final judgements touching +_particular cases_: there is nothing to show that the writer is +contemplating _general principles_, or advocating on deductive grounds +the dogma that specific characters must be necessarily and universally +adaptive characters. Therefore, what he here says is neither more nor +less than I have said. For I have always held that it would be "rather +rash" to conclude that any given cases of apparent inutility are +certainly cases of real inutility, _merely on the ground that utility is +not perceived_. But this is clearly quite a distinct matter from +resisting the _a priori_ generalization that all cases of apparent +inutility must certainly be cases of real utility. And, I maintain, in +every part of his writings, without any exception, where Darwin alludes +to this matter of general principle, it is in terms which directly +contradict the deduction in question. As the whole of this Appendix has +been directed to proving that such is the case, it will now, I think, be +sufficient to supply but one further quotation, in order to show that +the above "latest expression of opinion," far from indicating that in +his later years Darwin "inclined" to Mr. Wallace's views upon this +matter, is quite compatible with a distinct "expression of opinion" to +the contrary, in a letter written less than six years before his death. + + "In my opinion _the greatest error which I have committed_, has + been not allowing sufficient weight to the direct action of the + environment, i.e. food, climate, &c., _independently of natural + selection_. Modifications thus caused, _which are neither of + advantage nor disadvantage to the modified organisms_, would be + especially favoured, as I can now see chiefly through your + observations, _by isolation in a small area, where only a few + individuals lived under nearly uniform conditions_[154]." + + [154] _Life and Letters_, vol. iii. p. 158. + +I will now proceed to quote further passages from Darwin's works, which +appear to have escaped the notice of Mr. Wallace, inasmuch as they admit +of no doubt regarding the allusions being to _specific_ characters. + + "_We may easily err in attributing importance to characters, and in + believing that they have been developed through natural selection._ + We must by no means overlook the effects of the definite action of + changed conditions of life,--of so-called spontaneous variations, + which seem to depend in a quite subordinate degree on the nature of + the conditions,--of the tendency to reversion to long-lost + characters,--of the complex laws of growth, such as of + correlation[155], compensation, of pressure of one part on another, + &c., and finally of sexual selection, by which characters of use to + one sex are often gained and then transmitted more or less + perfectly to the other sex, though of no use to this sex. But + structures thus indirectly gained, _although at first of no + advantage to a species_, may subsequently have been taken advantage + of by its modified descendants, under new conditions of life and + newly acquired habits[156]." + + [155] It must be observed that Darwin uses this word, not as Mr. + Wallace always uses it (viz. as if correlation can only be + with regard to adaptive characters), but in the wider sense + that any change in one part of an organism--whether or not it + happens to be an adaptive change--is apt to induce changes in + other parts. + + [156] _Origin of Species_, pp. 157-8. + +It appeared--and still appears--to me, that where so many causes are +expressly assigned as producing useless _specific_ characters, and that +some of them (such as climatic influences and independent variability) +must be highly general in their action, I was justified in representing +it as Darwin's opinion that "a large proportional number of specific +characters" are useless to the _species_ presenting them, although +afterwards they may sometimes become of use to genera, families, &c. +Moreover, this passage goes on to point out that specific characters +which at first sight appear to be obviously useful, are sometimes found +by fuller knowledge to be really useless--a consideration which is the +exact inverse of the argument from ignorance as used by Mr. Wallace, and +serves still further to show that in Darwin's opinion utility is by no +means an invariable, still less a "necessary," mark of specific +character. The following are some of the instances which he gives. + + "The sutures in the skulls of young mammals have been advanced as a + beautiful adaptation for aiding parturition, and no doubt they may + facilitate, or be indispensable for this act; but as sutures occur + in the skulls of young birds and reptiles, which have only to + escape from a broken egg, we may infer that this structure has + _arisen from the laws of growth_, and has been taken advantage of + in the parturition of the higher animals[157]." + + "The naked skin on the head of a vulture is generally considered as + a direct adaptation for wallowing in putridity; and so it may be, + _or it may possibly be due to the direct action of the putrid + matter_; but we should be very cautious in drawing any such + inference [i.e. as to utility] when we see the skin on the head of + the clean-feeding male Turkey is likewise naked[158]." + + [157] _Ibid._ + + [158] _Origin of Species_, pp. 157-8. + +Similarly, in the _Descent of Man_ it is said:-- + + "Variations of the same _general_ nature have _often been taken + advantage of_ and accumulated through sexual selection in relation + to the propagation of the species, and through natural selection in + relation to the general purposes of life. Hence, _secondary sexual + characters, when equally transmitted to both sexes, can be + distinguished from ordinary specific characters, only by the light + of analogy_. The modifications acquired through sexual selection + are often so strongly pronounced that the two sexes have frequently + been ranked as distinct species, or even as distinct genera[159]." + + [159] _Descent of Man_, p. 615. + +As Mr. Wallace does not recognize sexual selection, he incurs the burden +of proving utility (in the life-preserving sense) in all these +"frequently" occurring cases where there are such "strongly pronounced +modifications," and we have already seen in the text his manner of +dealing with this burden. But the point here is, that whether or not we +accept the theory of sexual selection, we must accept it as Darwin's +opinion--first, that in their beginnings, as _specific_ characters, +these sexual modifications were often of a merely "_general nature_" (or +without reference to utility even in the life-embellishing sense), and +only _afterwards_ "have often been taken advantage of and accumulated +through _sexual_ selection": and, secondly, that "we know they have been +acquired in some instances _at the cost not only of inconvenience, but +of exposure to actual dangers_[160]." + + [160] _Ibid._ + +We may now pass on to some further, and even stronger, expressions of +opinion with regard to the frequent inutility of _specific_ characters. + + "I have made these remarks only to show that, if we are unable to + account for the characteristic differences of our several domestic + breeds, which nevertheless are generally admitted to have arisen + through ordinary generation from one or a few parent stocks, we + ought not to lay too much stress on our ignorance of the precise + cause [i.e. whether natural selection or some other cause] of the + slight analogous differences between true _species_.... I fully + admit that _many_ structures are now of no use to their possessors, + and may never have been of any use to their progenitors; but this + does not prove that they were formed solely for beauty or variety. + No doubt the definite action of changed conditions, and the various + causes of modification, lately specified, have all produced an + effect, _probably a great effect, independently of any advantage + thus gained_.... It is scarcely possible to decide how much + allowance ought to be made for such causes of change, as the + definite action of external conditions, so-called spontaneous + variations, and the complex laws of growth; but, _with these + important exceptions_, we may conclude that the structure of every + living creature either now is, or formerly was, of some direct or + indirect use to its possessor[161]." + + [161] _Descent of Man_, pp. 159-60. + +Here again, if we remember how "important" these "exceptions" are, I +cannot understand any one doubting Darwin's opinion to have been that a +large proportional number of specific characters are useless. For that +it is "species" which he here has mainly in his mind is evident from +what he says when again alluding to the subject in his "Summary of the +Chapter"--namely, "In _many_ other cases [i.e. in cases where natural +selection has not been concerned] modifications are probably the direct +result of the laws of variation or of growth, independently of any good +having been thus gained." Now, not only do these "laws" apply as much to +species as they do to genera; "but," the passage goes on to say, "even +such structures have often, we may feel assured, been subsequently +taken advantage of, and still further modified, for the good of +_species_ under new conditions of life." Obviously, therefore, the +inutility in such cases is taken to have been prior to any utility +subsequently acquired; and genera are not historically prior to the +species in which they originate. + +Here is another quotation:-- + + "Thus, as I am inclined to believe, morphological differences, + which we consider as important--such as the arrangement of the + leaves, the divisions of the flower or of the ovarium, the position + of the ovules, &c.--_first_ appeared in _many_ cases as + _fluctuating variations_, which sooner or later became constant + through the nature of the organism and of the surrounding + conditions, as well as through the intercrossing of distinct + individuals, _but not through natural selection_; for as these + morphological characters do not affect the welfare of the + _species_, any slight deviations in them could not have been + governed or accumulated through this latter agency. It is a strange + result which we thus arrive at, namely, that characters of slight + vital importance to the _species_, are the most important to the + systematist; but, as we shall hereafter see when we treat of the + genetic principle of classification, this is by no means so + paradoxical as it may at first appear[162]." + + [162] _Descent of Man_, p. 176. + +Clearly the view here expressed is that characters which are now +distinctive of higher taxonomic divisions "first appeared" in the parent +species of such divisions; for not only would it be unreasonable to +attribute the rise and preservation of useless characters to +"fluctuating variations" affecting a number of species or genera +similarly and simultaneously; but it would be impossible that, if such +were the case, they could be rendered "constant through the nature of +the organism and of the surrounding conditions, as well as through the +intercrossing of distinct individuals[163]." + + [163] The passage to which these remarks apply is likewise quoted, + in the same connexion as above, in my paper on _Physiological + Selection_. In criticising that paper in _Nature_ (vol. xxxix. + p. 127), Mr. Thiselton Dyer says of my interpretation of this + passage, "the obvious drift of this does not relate to + specific differences, but to those which are characteristic of + family." But in making this remark Mr. Dyer could not have + read the passage with sufficient care to note the points which + I have now explained. + +Here is another passage to the same general effect. In alluding to the +objection from inutility as advanced by Bronn, Broca, and Naegeli, Mr. +Darwin says:--"There is much force in the above objection"; and, after +again pointing out the important possibility in any particular cases of +hidden or former use, and the action of the laws of growth, he goes on +to say,--"In the third place, we have to allow for the direct and +definite action of changed conditions of life, and for so-called +spontaneous variations, in which the nature of the conditions plays +quite a subordinate part[164]." Elsewhere he says,--"It appears that I +formerly underrated the frequency and value of these latter forms of +variation as leading to permanent modifications of structure +_independently of natural selection_[165]." The "forms of variation" to +which he here alludes are "variations which seem to us in our ignorance +to arise spontaneously"; and it is evident that such variations cannot +well "arise" in two or more species of a genus similarly and +simultaneously, so as independently to lead "to permanent modifications +of structure" in two or more parallel lines. It is further evident that +by "spontaneous variations" Darwin alludes to extreme cases of +spontaneous departure from the general average of specific characters; +and therefore that lesser or more ordinary departures must be of still +greater "frequency." + + [164] _Origin of Species_, p. 171. + + [165] _Ibid._ p. 421. + +Again, speaking of the principles of classification, Darwin writes:-- + + "We care not how trifling a character may be--let it be the mere + inflection of the angle of the jaw, the manner in which an + insect's wing is folded, whether the skin be covered by hair or + feathers--if it prevail throughout many and different species, + especially those having very different habits of life, it assumes + high value [i.e. for purposes of classification]; for we can + account for its presence in so many forms with such _different + habits_, only by inheritance from a common parent. We may err in + this respect in regard to single points of structure, but when + several characters, let them be ever so trifling, concur throughout + a large group of beings _having different habits_, we may feel + almost sure, on the theory of descent, that these characters have + been inherited from a common ancestor; and we know that such + aggregated characters have especial value in classification[166]." + + [166] _Origin of Species_, pp. 372-373. + +Now it is evident that this argument for the general theory of evolution +would be destroyed, if Wallace's assumption of utility of specific +characters as universal were to be entertained. And the fact of +apparently "trifling" characters occurring throughout a large group of +beings "having different habits" is proof that they are really trifling, +or without utilitarian significance. + +It is needless to multiply these quotations, for it appears to me that +the above are amply sufficient to establish the only point with which we +are here concerned, namely, that Darwin's opinion on the subject of +utility in relation to specific characters was substantially identical +with my own. And this is established, not merely by the literal meaning +of the sundry passages here gathered together from different parts of +his writings; but likewise, and perhaps still more, from the tone of +thought which pervades these writings as a whole. It requires no words +of mine to show that the literal meaning of the above quotations is +entirely opposed to Mr. Wallace's view touching the _necessary_ utility +of _all_ specific characters; but upon the other point--or the general +tone of Mr. Darwin's thought regarding such topics--it may be well to +add two remarks. + +In the first place, it must be evident that so soon as we cease to be +bound by any _a priori_ deduction as to natural selection being "the +exclusive means of modifications," it ceases to be a matter of much +concern to the theory of natural selection in what proportion other +means of modification have been at work--especially when non-adaptive +modifications are concerned, and where these have reference to merely +"specific characters," or modifications of the most incipient kind, +least generally diffused among organic types, and representing the +incidence of causes of less importance than any others in the process of +organic evolution considered as a whole. Consequently, in the second +place, we find that Darwin nowhere displays any solicitude touching the +proportional number of specific characters that may eventually prove to +be due to causes other than natural selection. He takes a much wider and +deeper view of organic evolution, and, having entirely emancipated +himself from the former conception of species as the organic units, sees +virtually no significance in specific characters, except in so far as +they are also adaptive characters. + +Such, at all events, appears to me the obvious interpretation of his +writings when these are carefully read with a view to ascertaining his +ideas upon "Utilitarian doctrine: how far true." And I make these +remarks because it has been laid to my charge, that in quoting such +passages as the above I have been putting "a strained interpretation" +upon Darwin's utterances: "such admissions," it is said, "Mr. Romanes +appears to me to treat as if wrung from a hostile witness[167]." But, +from what has gone before, it ought to be apparent that I take precisely +the opposite view to that here imputed. Far from deeming these and +similar passages as "admissions wrung from a hostile witness," and far +from seeking to put any "strained interpretation" upon them, I believe +that they are but the plain and unequivocal expressions of an opinion +which I have always understood that Darwin held. And if any one has been +led to think otherwise, I throw back this charge of "strained +interpretation," by challenging such a person to adduce a single +quotation from any part of Darwin's works, which can possibly be held to +indicate that he regarded passages like those above quoted as in any way +out of conformity with his theory of natural selection--or as put +forward merely to "admit the possibility of explanations, to which +really, however, he did not attach much importance." To the best of my +judgement it is only some bias in favour of Mr. Wallace's views that can +lead a naturalist to view in this way the clear and consistent +expression of Darwin's. + + [167] Mr. Thiselton Dyer in _Nature_, _loc. cit._ + +That Mr. Wallace himself should be biassed in this matter might, +perhaps, be expected. After rendering the following very unequivocal +passage from the _Origin of Species_ (p. 72)--"There can be little doubt +that the tendency to vary in the same manner has often been so strong, +_that all individuals of the same species have been similarly modified +without the aid of any form of selection_"--Mr. Wallace says, "But no +proof whatever is offered of this statement, and it is so entirely +opposed to all we know of the facts of variation as given by Darwin +himself, that the important word 'all' is probably an oversight." But, +if Mr. Wallace had read the very next sentence he would have seen that +here the important word "all" could not _possibly_ have been "an +oversight." For the passage continues,--"Or only a third, fifth, or +tenth part of the individuals may have been thus affected, of which fact +several instances could be given. Thus Graba estimates that about +one-fifth of the guillemots in the Faroe Islands consist of a variety so +well marked, that it was formerly ranked as a distinct species under the +name of Uria lacrymans." And even if this passage had not been thus +specially concerned with the question of the _proportion_ in which +"_individuals of the same species have been similarly modified without +the aid of any form of selection_" the oversight with respect to "the +important word 'all'" would still have remained an oversight of a +recurrent character, as the following additional quotations from other +parts of Darwin's writings may perhaps render apparent. + + "There must be some efficient cause for each slight individual + difference, as well as for more strongly marked variations which + occasionally arise; and if the unknown cause were to act + persistently, it is almost certain that _all_ the individuals of + the _species_ would be similarly modified[168]." + + "The acquisition of a useless part can hardly be said to raise an + organism in the natural scale.... We are so ignorant of the + exciting cause of the above specified modifications; but if the + unknown cause were to act almost uniformly for a length of time, we + may infer that the result would be almost uniform; and in this case + _all_ the individuals of the _species_ would be modified in the + same manner[169]." + + [168] _Origin of Species_, p. 171. + + [169] _Ibid._ p. 175. + +Moreover, when dealing even with such comparatively slight changes as +occur between our domesticated varieties--and which, _a fortiori_, are +less likely to become "stable" through the uniform operation of causes +other than selection, seeing that they are not only smaller in amount +than occurs among natural species, but also have had but a comparatively +short time in which to accumulate--Darwin is emphatic in his assertion +of the same principles. For instance, in the twenty-third chapter of the +_Variation of Plants and Animals under Domestication_, he repeatedly +uses the term "definite action of external conditions," and begins the +chapter by explaining his use of the term thus:-- + + "By the term definite action, as used in this chapter, I mean an + action of such a nature that, when many individuals of the same + variety are exposed during several generations to any change in + their physical conditions of life, _all_, or _nearly all_, the + individuals are modified in the same manner. A new _sub-variety_ + would thus be produced _without the aid of selection_[170]." + + [170] _Variation_, &c., vol. ii. p. 260. + +As an example of the special instances that he gives, I may quote the +following from the same work:-- + + "Each of the endless variations which we see in the plumage of our + fowls must have had some efficient cause; and if the same cause + were to act uniformly during a long series of generations on many + individuals, _all_ probably would be modified in the same manner." + +And, as instances of his more general statements in Chapter XXIII, these +may suffice:-- + + "The direct action of the conditions of life, whether leading to + definite or indefinite results, _is a totally distinct + consideration from the effects of natural selection_.... The direct + and definite action of changed conditions, in contradistinction to + the accumulation of indefinite variations, _seems to me so + important_ that I will give a large additional body of + miscellaneous facts[171]." + + [171] _Ibid._ vol. ii. p. 261. + +Then, after giving these facts, and showing how in the case of species +in a state of nature it is often impossible to decide how much we are to +attribute to natural selection and how much to the definite action of +changed conditions, he begins his general summary of the chapter thus:-- + + "There can be no doubt, from the facts given in the early part of + this chapter, that extremely slight changes in the conditions of + life sometimes act in a definite manner on our already variable + domesticated productions [productions, therefore, with regard to + which uniformity and 'stability' of modification are least likely + to arise]; and, as the action Of changed conditions in causing + general or indefinite variability is accumulative, so it may be + with their definite action. Hence it is possible that _great_ and + _definite_ modifications of structure may result from altered + conditions acting during a long series of generations. In some few + instances a marked effect has been produced quickly on _all_, or + _nearly all_, the individuals which have been exposed to some + considerable change of climate, food, or other circumstance[172]." + + [172] _Variation_, &c., vol. ii. p. 280. + +Once more, in order to show that he retained these views to the end of +his life, I may quote a passage from the second edition of the _Descent +of Man_, which is the latest expression of his opinion upon these +points:-- + + "Each of the endless diversities in plumage, which we see in our + domesticated birds, is, of course, the result of some definite + cause; and under natural and more uniform conditions, some one + tint, _assuming that it was in no way injurious, would almost + certainly sooner or later prevail_. The free-intercrossing of the + many individuals belonging to the same species would ultimately + tend to make any change of colour thus induced _uniform in + character_.... Can we believe that the very slight differences in + tints and markings between, for instance, the female black-grouse + and red-grouse serve as a protection? Are partridges as they are + now coloured, better protected than if they had resembled quails? + Do the slight differences between the females of the common + pheasant, the Japan and golden pheasants, serve as a protection, or + might not their plumage have been interchanged with impunity? From + what Mr. Wallace has observed of the habits of certain gallinaceous + birds in the East, he thinks that such slight differences are + beneficial. For myself, I will only say, I am not convinced[173]." + + [173] _Descent of Man_, pp. 473-4. + +Yet "convinced" he certainly must have been on merely _a priori_ +grounds, had he countenanced Mr. Wallace's reasoning from the general +theory of natural selection; and the fact that he here fails to be +convinced even by "what Mr. Wallace has observed of the habits of +certain gallinaceous birds," appears to indicate that he had considered +the question of utility with special reference to Mr. Wallace's opinion. +That opinion was then, as now, the avowed result of a theoretical +prepossession; and this prepossession, as the above quotations +sufficiently show, was expressly repudiated by Darwin. + +Lastly, this is not the only occasion on which Darwin expressly +repudiates Mr. Wallace's opinion on the point in question. For it is +notorious that these co-authors of the theory of natural selection have +expressed divergent opinions concerning the origin by natural selection +of the most general of all specific characters--cross-sterility. +Although allowing that cross-sterility between allied species may be of +adaptive value in "keeping incipient species from blending," Darwin +persistently refused to be influenced by Wallace's belief that it is due +to natural selection; i.e. the belief on which alone can be founded the +"necessary deduction" with which we have been throughout concerned. + + + + +NOTE A TO PAGE 57. + + +I think it is desirable here to adduce one or two concrete illustrations +of these abstract principles, in order to show how, as a matter of fact, +the structure of Weismann's theory is such as to preclude the +possibility of its assumptions being disproved--and this even supposing +that the theory is false. + +At first sight nothing could seem more conclusive on the side of +Darwinian or Lamarckian principles than are the facts of hereditary +disease, in cases where the disease has unquestionably been acquired by +the parents. Take, for example, the case of gout. Here there is no +suspicion of any microbe being concerned, nor is there any question +about the fact of the disease being one which is frequently acquired by +certain habits of life. Now, suppose the case of a man who in middle age +acquires the gout by these habits of life--such as insufficient +exercise, over-sufficient food, and free indulgence in wine. His son +inherits the gouty diathesis, and even though the boy may have the fear +of gout before his eyes, and consequently avoid over-eating and +alcoholic drinking, &c., the disease may overtake him also. Well, the +natural explanation of all this is, that the sins of the fathers descend +upon the children; that gout acquired may become in the next generation +gout transmitted. But, on the other hand, the school of Weismann will +maintain that the reason why the parent contracted the gout was because +he had a congenital, or "blastogenetic," tendency towards that +disease--a tendency which may, indeed, have been intensified by his +habits of life, but which, in so far as thus intensified, was not +transmitted to his offspring. All that was so transmitted was the +congenital tendency; and all that is proved by such cases as those above +supposed, where the offspring of gouty parents become gouty +notwithstanding their abstemious habits, is that in such offspring the +congenital tendency is even more pronounced than it was in their +parents, and therefore did not require so much inducement in the way of +unguarded living to bring it out. Now, here again, without waiting to +consider the relative probabilities of these two opposing explanations, +it is enough for the purposes of the illustration to remark that it is +obviously impossible to disprove either by means of the other, or by any +class of facts to which they may severally appeal. + +I will give only one further example to show the elusiveness of +Weismann's theory, and the consequent impossibility of finding any cases +in nature which will satisfy the conditions of proof which the theory +imposes. In one of his papers Weismann says that if there be any truth +in the Lamarckian doctrine of the transmission of acquired characters, +it ought to follow that the human infant should speak by instinct. For, +ever since man became human he has presumably been a talking animal: at +any rate it is certain that he has been so for an innumerable number of +generations. Therefore, by this time the faculty of language ought to +have been so deeply impressed upon the psychology of the species, that +there ought to be no need to teach the young child its use of language; +and the fact that there is such need is taken by Weismann to constitute +good evidence in proof of the non-transmissibility of individually +acquired characters. Or, to quote his own words, "it has never yet been +found that a child could read of itself, although its parents had +throughout their whole lives practised this art. Not even are our +children able to talk of their own accord; yet not only have their +parents, but, more than that, an infinitely long line of ancestors have +never ceased to drill their brains and to perfect their organs of +speech.... From this alone we may be disposed to doubt whether acquired +capabilities in the true sense can ever be transmitted." Well, in answer +to this particular case, we have first of all to remark that the +construction of even the simplest language is, psychologically +considered, a matter of such enormous complexity, that there is no real +analogy between it and the phenomena of instinct: therefore the fact +that Lamarckian principles cannot be applied to the case of language is +no evidence that they do not hold good as regards instinct. Secondly, +not only the construction, but still more the use of language is quite +out of analogy with all the phenomena of instinct; for, in order to use, +or speak, a language, the mind must already be that of a thinking agent; +and therefore to expect that language should be instinctive is +tantamount to expecting that the thought of which it is the vehicle +should be instinctive--i.e. that human parents should transmit the whole +organization of their own intellectual experiences to their unborn +children. Thirdly, even neglecting these considerations, we have to +remember that language has been itself the product of an immensely long +course of evolution; so that even if it were reasonable to expect that a +child should speak by instinct without instruction, it would be +necessary further to expect that the child should begin by speaking in +some score or two of unknown tongues before it arrived at the one which +alone its parents could understand. Probably these considerations are +enough to show how absurd is the suggestion that Darwinians ought to +expect children to speak by instinct. But, now, although it is for these +reasons preposterous under any theory of evolution to expect that +children should be able to use a fully developed language without +instruction, it is by no means so preposterous to expect that, if all +languages present any one simple set of features in common, these +features might by this time have grown to be instinctive; for these +simple features, being common to all languages, must have been +constantly and forcibly impressed upon the structure of human psychology +throughout an innumerable number of sequent generations. Now, there is +only one set of features common to all languages; and this comprises the +combinations of vowel and consonantal sounds, which go to constitute +what we know as articulate syllables. And, is it not the case that these +particular features, thus common to all languages, as a matter of fact +actually _are_ instinctive? Long before a young child is able to +understand the meanings of any words, it begins to babble articulate +syllables; and I do not know that a more striking fact can be adduced at +the present stage of the Weismann controversy than is this fact which he +has thus himself unconsciously suggested, namely, that the young of the +only talking animal should be alone in presenting--and in unmistakably +presenting--the instinct of articulation. Well, such being the state of +matters as regards this particular case, in the course of a debate which +was held at the Newcastle meeting of the British Association upon the +heredity question, I presented this case as I present it now. And +subsequently I was met, as I expected to be met, by its being said that +after all the faculty of making articulate sounds might have been of +congenital origin. Seeing of how much importance this faculty must +always have been to the human species, it may very well have been a +faculty which early fell under the sway of natural selection, and so it +may have become congenital. Now, be it remembered, I am only adducing +this case in illustration of the elusiveness of Weismann's theory. First +of all he selects the faculty of articulate speech to argue that it is a +faculty which ought to be instinctive if acquired characters ever do +become instinctive; and so good does he deem it as a test case between +the two theories, that he says _from it alone_ we should be prepared to +accept the doctrine that acquired characters can never become +congenital. Then, when it is shown that the only element in articulate +speech which possibly could have become congenital, actually has become +congenital, the answer we receive is a direct contradiction of the +previous argument: the faculty originally selected as representative of +an acquired character is now taken as representative of a congenital +one. By thus playing fast and loose with whatever facts the followers of +Darwin may adduce, the followers of Weismann bring their own position +simply to this:--All characters which can be shown to be inherited we +assume to be congenital, or as we term it, "blastogenetic," while all +characters which can be shown not to be inherited, we assume to be +acquired, or as we term it, "somatogenetic"--and this merely on the +ground that they have been shown to be inherited or not inherited as the +case may be. Now, there need be no objection to such assumptions, +provided they are recognized as assumptions; but so long as the very +question in debate has reference to their validity as assumptions, it is +closely illogical to adduce them as arguments. And this is the only +point with which we are at present concerned. + + + + +NOTE B TO PAGE 89. + + +In answer to this illustration as previously adduced by me, Mr. Poulton +has objected that the benefit arising from the peculiar mode of stinging +in question is a benefit conferred, not on the insect which stings, but +upon its progeny. The point of the illustration however has no reference +to the maternal instinct (which here, as elsewhere, I doubt not is due +to natural selection); it has reference only to the particular instinct +of selective stinging, which here ministers to the purposes of the other +and more general instinct of rearing progeny. Given then the maternal +instinct of stinging prey for the use of progeny, the question is--What +first determined the ancestors of the Sphex to sting their prey only in +nine particular points? Darwin's answer to this question is as +follows:-- + + "I have been thinking about Pompilius and its allies. Please take + the trouble to read on perforation of the corolla by Bees, p. 425 + of my 'Cross-fertilization,' to end of chapter. Bees show so much + intelligence in their acts, that it seems not improbable to me that + the progenitors of Pompilius originally stung caterpillars and + spiders, &c., in any part of their bodies, and then observed by + their intelligence that if they stung them in one particular place, + as between certain segments on the lower side, their prey was at + once paralyzed. It does, not seem to me at all incredible that this + action should then become instinctive, i.e. memory transmitted from + one generation to another. It does not seem necessary to suppose + that when Pompilius stung its prey in the ganglion it intended or + knew that their prey would keep long alive. The development of the + larvae may have been subsequently modified in relation to their + half-dead, instead of wholly dead prey; supposing that the prey was + at first quite killed, which would have required much stinging. + Turn this over in your mind," &c. + +Weismann, on the other hand, can only suppose that this intensely +specialized instinct had its origin in fortuitous variations in the +psychology of the species. But, neglecting the consideration that, in +order to become fixed as an instinct by natural selection, the +particular variation required must have occurred in many different +individuals, not only in the first, but also in the sequent generations, +the chances against its occurring only once, or in but one single +individual case, are many thousands if not millions to one. + + + + +INDEX + + +A. + +Acceleration and retardation, 16. + +Acquired characters, heredity of, 39, 103, 133. + +Adaptation, 7, 13, 55, 62, 67, 71, 159, 165; + of species and of specific characters, 166. + +ALLEN, Mr., referred to, 209. + +_All-sufficiency of Natural Selection_, referred to, 65, 95. + +_Alone with the Hairy Ainu_, referred to, 26. + +American and European trees compared, 201. + +_American Journal of Science_, referred to, 273. + +_American Naturalist_, referred to, 35, 58. + +Ammonites, species of, 254. + +_Animal Intelligence_, referred to, 93. + +_Animal Life_, referred to, 101. + +_Animal Life and Intelligence_, referred to, 33, 36. + +_Apparent Paradox in Mental Evolution_, referred to, 90. + +Appendages of Normandy and Irish pigs, 188. + +Articulation and inheritance, 335. + +Artistic faculties of man, 27. + + +B. + +BABINGTON, Prof., referred to, 252. + +BACHMAN, Dr., referred to, 186. + +BAILEY, Prof., referred to, 127. + +BAKER, Mr., referred to, 252. + +Balancing of brainless frog, 78. + +BALL, Mr. Platt, referred to, 3, 95; quoted, 50. + +BATESON, Mr. W., referred to, 36. + +BEDDARD, Mr. F., referred to, 174. + +BENTHAM, Mr., referred to, 252. + +Birds, diagnostic characters of, 176; + of Australia, effect of climate on, 210; + influence of food on, 218. + +Blastogenetic, 123, 242, 245, 250. + +Blending of adaptations, 67. + +_Brain_, referred to, 80. + +BROCA, Prof., referred to, 64, 67, 174, 318. + +BRONN, Prof., referred to, 174. + +BROOKS, Prof., referred to, 14. + +BROWN-SEQUARD, referred to, 104, 122, 142; quoted, 104. + +BUCKLEY, Mr., referred to, 147. + +BUCKMAN, Prof. James, referred to, 125. + +BUCKMAN, Prof. S.S., referred to, 24. + +BUTLER, Mr. A. G., referred to, 254. + +BUTLER, Mr. Samuel, referred to, 87. + +Butterfly, seasonal changes of, 210; + influence of food on, 217. + + +C. + +Carnivora, instincts of, 89. + +CARRIERE, M. L. A., referred to, 123. + +Cave animals, colour-changes in, 211. + +_Cave Fauna of North America_, quoted, 211. + +Cessation of Selection, 99, 199, 212, 292. + +Characters, adaptive and specific, 159, 307; + specific, due to Natural Selection, 171. + +_Charadriidae, Geographical Distribution of the Family_, quoted, 173. + +Chimpanzee, counting of, 31. + +Climate, influence of, on plants, 200; + on animals, 209. + +Co-adaptation, 64. + +COCKERELL, Prof., referred to, 218. + +Colour, 269. + +Colour-changes in butterflies, 210. + in cave animals, 211. + +_Colours of Animals_, referred to, 36. + +Congenital, as opposed to acquired characters, 134. + +Constancy of characters not necessarily due to Natural Selection, 186. + +_Contemporary Review_, referred to, 60, 65, 95 + +Continuity of germ-plasm, 44, 61, 133; + absolute and relative, 134, 155. + +_Contributions to the Theory of Natural Selection_, referred to, 2; +quoted, 180. + +COPE, Prof., referred to, 14, 15, 20, 63, 256; quoted, 16. + +Correlation, 171, 184, 211, 222, 268. + +COSTA, M., quoted, 217. + +CUNNINGHAM, Mr. J. T., quoted, 103; referred to, 95, 122. + + +D. + +DALL, Prof., referred to, 14. + +DARWIN, Charles, referred to, 1-13, 20-22, 25, 44, 45, 51-53, 56, 66, +67, 74, 87, 88, 93, 95, 96-100, 149, 159, 160, 167, 173, 174, 181-183, +187-191, 193, 195, 198, 200-202, 213-216, 218, 219, 226, 256, 261-265, +268, 271, 277, 283, 287, 291, 305-307, 313-332, 337; quoted, 11, 53, 66, +96, 181, 182, 186-191, 193, 195, 201, 202, 213-215, 261, 262, 265, +313-316, 319-322, 324-326, 328-331, 337. + +_Darwin et ses Precurseurs Francais_, referred to, 234. + +_Darwinian Theory of the Origin of Species_, quoted, 254. + +_Darwinism_, quoted, 22, 27, 67, 181, 182, 186, 189-191, 221, 222, 235, +236, 252, 253, 269, 270, 273, 313, 316; referred to, 7, 12, 15, 20, 70. + +DE CANDOLLE, Prof., referred to, 206. + +Deep-sea faunas, 212. + +DELB[OE]UF, referred to, 224. + +_Descent of Man_, quoted, 25, 322-324, 331. + +_Development of the Hard Parts of the Mammalia_, referred to, 14. + +DE VRIES, Prof., referred to, 122, 174. + +Diagnostic characters of birds, 176; + Marsupials, 178. + +Divergent Evolution through Cumulative Segregation, quoted, 224. + +DIXON, Mr. Charles, referred to, 174; quoted, 177, 223. + +_Doctrine of Descent and Darwinism_, quoted, 260. + +Dogs, scratching, reflex of, 80; + shaking off water, 84; + transplantation of ovaries, 143. + +DORFMEISTER, Dr., referred to, 211. + +Ducks, use-inheritance in, 96; + losing true plumage, 187. + +DUPUY, Dr., referred to, 105. + +DYER, Mr. Thistleton, quoted, 325, 327. + + +E. + +_Effect of External Influences upon Development_, referred to, 66, 95. + +_Effects of Use and Disuse_, quoted, 50. + +EIMER, Prof., referred to, 14, 174, 217. + +_Entomological Society, Trans. of_, quoted, 211; referred to, 217. + +Epilepsy of guinea-pigs, 104. + +_Essays on Heredity_, quoted, 56, 91, 97, 107, 152; referred to, 12, 36, +65, 105, 110. + +EUDES-DESLONGCHAMPS, M., referred to, 188. + +European and American trees, compared, 201. + +EVEREST, Rev. E., quoted, 213. + +_Evolution without Natural Selection_, quoted, 177. + +_Examination of Weismannism_, referred to, 39-42, 44, 100, 122, 123, +134, 136, 138-140, 156. + +_Experiments in Pangenesis_, referred to, 145. + + +F. + +FABRE, M., referred to, 88. + +Factors of organic evolution: + Natural Selection, 2, 5, 6; + use-inheritance, 3, 11. + +_Factors of Organic Evolution_, referred to, 8. + +Faculties and organs, 29. + +Fertility, 229. + +Flat-fish, Mr. Cunningham on, 103. + +_Floral Structures_, referred to, 19. + +FOCKE, Dr., referred to, 174. + +_Fonctions du Cerveau_, referred to, 109. + +Food, influence of, 217. + +Foot, of man, 23. + +Frog, brainless, balancing of, 78. + + +G. + +GALTON, Mr. Francis, referred to, 40-48, 100, 103, 134-139, 145, 146, +152, 154, 156, 300, 303-305; quoted, 46, 100. + +Gangrene, effects of, 54, 105. + +_Gardener's Chronicle_, quoted, 127. + +GAERTNER, Dr., referred to, 206. + +GEDDES, Prof., referred to, 15, 20,174. + +Gemmules, 47, 145, 155. + +Genera and species, 261. + +Germ-plasm and Stirp, 40; + and pangenesis, 42; + isolation of, 137; + stability of, 243. + +_Germ-plasm_, referred to, 128. + +GIARD, Prof., referred to, 14, 174. + +Giraffe, co-adaptation in, 64. + +GOLTZ, Prof., referred to, 80, 84. + +GOULD, Mr., referred to, 210. + +Graft-hybridization, 143. + +Growth, laws of, 222, 226, 248, 270, 321. + +Guinea-pigs, epilepsy of, 104. + +GULICK, Mr., referred to, 174, 259, 260, 271; quoted, 224, 273. + +_Gute und schlechte Arten_, quoted, 203. + + +H. + +Habit, hereditary, 87. + +_Habit and Intelligence_, quoted, 225. + +Hand, of man, 24. + +_Handbook of British Flora_, referred to, 252. + +HAYCRAFT, Prof., referred to, 80. + +HEAPE, Mr. Walter, referred to, 147. + +HENSLOW, Prof. George, referred to, 18-20, 127-132, 174, 208; quoted, +19, 130, 131. + +Heredity, problems of, 39. + +HERING, Prof., referred to, 87. + +HEWITT, Mr., referred to, 187. + +HILL, Prof. Leonard, quoted, 132. + +HAECKEL, Prof., referred to, 174, 260, 282. + +HOFFMANN, Dr., referred to, 123, 280. + +Horse, callosities of, 265. + +HUXLEY, Prof. T. H., referred to, 167-170, 185, 256, 275, 283, 307-312; +quoted, 307-309. + +Huxleyan doctrine of species, 167. + +_Hyatt_, Prof., referred to, 14, 15. + +Hymenoptera, social, 92. + + +I. + +_Inadequacy of Natural Selection_, referred to, 65, 95. + +_Inconsistencies of Utilitarianism as the Exclusive Theory of Organic +Evolution_, quoted, 273. + +Indifferent characters, 171, 185, 208, 247. + +Insects, instincts of, 91. + +Instability of useless characters, 186. + +Instinct and hereditary habit, 87; + of Sphex, 88; + of carnivora, 89; + of man, 89; + Prof. Weismann's views on, 90; + of insects, 91. + +Intercrossing, 67-71. + +Isolation, 223 _et seq._ + + +J. + +JORDAN, Dr., referred to, 206, 252. + + +K. + +Karyokinesis, 140. + +KERNER, Prof., referred to, 174, 202-206, 231, 239, 260, 282; quoted, +203. + +KOCH, Dr., referred to, 217. + +KOELLIKER, Prof., referred to, 174. + + +L. + +Lamarck, referred to, 9-15. + +Lamarckism, 9, 61, 113. + +LANDOR, A. H. Savage, referred to, 26. + +Language and Weismannism, 334. + +LANKESTER, Prof. Ray, quoted, 245, 299; referred to, 305. + +LESAGE, M., referred to, 126. + +_Life and Letters of Charles Darwin_, quoted, 319, 320; referred to, 11. + +LUCIANI, referred to, 109. + + +M. + +_Making of Flowers_, referred to, 19. + +_Manual of British Botany_, referred to, 252. + +_Manual of Dental Anatomy_, figure from, 267. + +Marsupials, diagnostic characters of, 178. + +_Materials for the Study of Variation_, referred to, 36. + +MEEHAN, Mr., referred to, 201. + +MELDOLA, Prof., referred to, 68. + +_Mental Evolution in Animals_, referred to, 25, 88, 89, 92. + +_Mental Evolution in Man_, referred to, 31. + +MERRIFIELD, Mr., referred to, 211. + +Mice, mutilation of tails of, 148. + +MIVART, Prof. St. George, referred to, 4, 174, 217. + +Monstrosity, in turkeys, 181; + in cattle, 196. + +MORGAN, Prof. Lloyd, referred to, 33, 36, 174, 271, 300-305; quoted, +300, 303. + +MOSELEY, Prof., referred to, 26. + +MURPHY, Mr. J. J., referred to, 224. + +Mutilations, inheritance of, 53, 148. + + +N. + +NAEGELI, Prof., referred to, 174, 206, 318. + +Naked skin of man, 25. + +NATHUSIUS, referred to, 188. + +Natural Selection, range of, 2, 5, 51, 62, 92; + a theory of species, 161, 169; + and cave animals, 211; + and Porto Santo rabbits, 214. + +_Natural Selection and Tropical Nature_, quoted, 23. + +_Natural Science_, quoted, 104. + +_Nature_, quoted, 132, 223, 245, 299, 325; referred to, 68, 98, 218. + +Neo-Darwinian school, 10, 61. + +Neo-Lamarckian school, 13, 62, 63. + +_Neuer Beitrag zum geologischen Beweis der Darwin'schen Theorie_, +quoted, 254. + +_Neuter Insects and Darwinism_, referred to, 95. + +_Neuter Insects and Lamarckism_, referred to, 95. + +Neuters of hymenopterous insects, 92. + +NEWMAN, Cardinal, referred to, 20. + +Niata cattle, 191. + + +O. + +OBERSTEINER, Dr., referred to, 105, 106. + +_Oesterreichische medicinische Jahrbuecher_, referred to, 105. + +_On Truth_, referred to, 217. + +Orang-utan, teeth of, 267. + +_Organic Evolution_, referred to, 217. + +_Origin of the Fittest_, quoted, 16; referred to, 14. + +_Origine des Plantes Domestiques, demontree par la culture du Radis +sauvage_, referred to, 123. + +_Origin of Sex_, referred to, 17. + +_Origin of Species_, quoted, 3, 4, 181, 182, 186, 188, 190, 261, 262, +265, 321, 322, 325, 326, 329; referred to, 67, 159, 227, 286. + +OSBORN, Prof., referred to, 14, 58, 63. + +OWEN, Sir Richard, referred to, 191. + +Oxen, skulls of, compared, 192. + +Oysters, change of, 217. + + +P. + +PACKARD, Prof., referred to, 14, 213. + +Pangenesis, 11, 42. + +Panmixia, 97, 212, 291. + +Parsimony, law of, 51. + +Parsnips, variation of, 125. + +PASCOE, Mr., referred to, 174; quoted, 254. + +PERRIER, Prof., referred to, 14, 93, 95. + +PETER, Dr., referred to, 206. + +PFEFFER, Herr, referred to, 15. + +_Pflueger's Archiv_, referred to, 80. + +_Philosophical Transactions_, referred 10, 103. + +_Physiological Selection_, referred to, 187, 307, 313, 324; quoted, 188, +308. + +_Pickard-Cambridge_, Rev. O., quoted, 221. + +Pig, old Irish, 188. + +Plants, influence of climate on, 122-207. + +Porto Santo rabbits, 214. + +POULTON, E. B., referred to, 36, 217, 337. + +_Presidential Address to the Bristol Naturalists Society_, 1891; quoted, +300, 303. + +_Proceedings of the Royal Society_, referred to, 145, 147; quoted, 307. + +Protective resemblance, 72. + +Protrusion of eyeball, in epileptic guinea-pigs, 111. + + +Q. + +QUATREFAGES, M., referred to, 234. + + +R. + +Rabbits, and use-inheritance, 96; + transplantation of ovaries, 143; + Porto Santo, 214. + +Radish, variation of, 123. + +Rats, scratching, reflex of, 81. + +_Raupen und Schmetterlinge der Wetterau_, referred to, 217. + +Reflex action and use-inheritance, 64-87. + +_Rejoinder to Prof. Weismann_, referred to, 95. + +Reversal of selection, 101, 292. + +_Revue Generale de Botanie_, referred to, 126. + +RICHARDSON, referred to, 188. + +ROUX, Prof., referred to, 298. + +Rudiments, 294. + +RYDER, Prof., referred to, 14. + + +S. + +SACHS, Prof., referred to, 15, 174. + +"Sally," counting of, 31. + +SAUERMANN, Dr., referred to, 218. + +SCHAEFER, Prof., referred to, 145. + +_Schmetterlinge des Suedwestlichen Deutschlands_, referred to, 217. + +SCHMIDT, Dr. Oscar, quoted, 260. + +Schools of Evolutionists, 12-20. + +SCOTT, Prof., referred to, 63. + +Scratching, reflex, in dogs, 80; + in rats, 81. + +Seasonal changes of butterflies, 210. + +SEEBOHM, Mr. Henry, quoted, 173; referred to, 174. + +Selection, cessation of, 99, 292; + reversal of, 101, 292. + +Selection, sexual, 219 _et seq._ + +Selective value, 73. + +Self-adaptation, 18. + +SEMPER, Prof. Karl, referred to, 101. + +Sexual selection, 219 _et seq._ + +Sole, pigment of, 104. + +Somatogenetic and somatoplasm, 123, 137, 155, 242-249. + +_Some Laws of Heredity_, referred to, 24. + +Species, stress laid on origin of, 159; + necessarily due to natural selection, 168. + +---- definitions of, 229. + +SPENCER, Herbert, referred to, 8, 64-68, 95. + +Sphex, instincts of, 88, 337. + +STEBBING, Rev. T. R., quoted, 25. + +Sterility, 8. + +Stirp and germ-plasm, 40, 47, 138. + +_Struggle for Existence between the parts of an Organism_, referred to, +299. + + +T. + +Theory of Heredity, referred to, 40, 47, 137, 154; quoted, 46, 47. + +THOMAS, Mr. Oldfield, referred to, 178. + +THOMSON, J. A., referred to, 15. + +TODD, J. E., referred to, 35. + +TOMES, Mr., referred to, 267. + +Transfusion of blood in rabbits, 145. + +Transplantation of ovaries in rabbits, 143, 147. + +Trees, comparison of European and American, 201. + +Turkey, tuft of hair of, 181; + losing metallic tints, 186. + + +U. + +Use-inheritance, 3, 49, 77, 95, 151. + +Utility, law of, 8, 20, 159; + universality of, 166; + of specific characters, 172; + of specific characters in birds, 176; + of specific characters in Mammals, 178. + + +V. + +_Variation of Animals and Plants under Domestication_, quoted, 3, 4, 53, +66, 96, 187, 189, 191, 193, 195, 213-216, 330, 331. + +Varieties, climatic, 228. + +Vestigial characters, 171, 184, 261, 294. + +VINES, Prof., referred to, 297. + +Vitality, plumes of birds due to surplus, 270, 25. + +Voice, of man, 25. + + +W. + +WAGNER, Moritz, referred to, 217. + +WALLACE, Mr. A. R., referred to, 2, 6, 9, 11, 15, 20-35, 50, 66-70, 167, +169, 172-175, 180-198, 210, 218-227, 235-237, 252, 256, 258, 263-278, +285, 313-322, 328, 331, 332; quoted, 22-24, 27, 67, 180-182, 185, 186, +190, 191, 221-223, 235, 236, 269, 273, 313. + +Wallacean doctrine of species, 167, 169. + +WEISMANN, Prof., referred to, 2, 7, 9, 12, 13, 39-60, 65, 66, 90-105, +112, 128, 134-142, 148, 149, 151, 152, 155, 156, 173, 241, 243, 244, +246, 279, 280, 291, 294, 297, 298, 300, 311, 338; quoted, 56, 91, 97, +152, 243, 244, 297. + +Weismannism, diagram of constituent theories, 43, 136; + elusiveness of, 334. + +_Weismannism once more_, referred to, 66, 95. + +WELBY, Hon. Lady, referred to, 90. + +WESTPHAL, Prof., referred to, 105, 107. + +Withdrawal of foot by reflex action, 75. + +WUERTENBERGER, Dr., referred to, 254. + + +Y. + +YARRELL, Mr., referred to, 186. + + + + +LIST OF OPEN COURT PUBLICATIONS ON SCIENCE + + +The Primary Factors of Organic Evolution. By E. D. Cope. Second +edition. Pages, 550; illustrations, 121; tables, bibliography, and +index. Cloth, $2.00 net. + + A comprehensive handbook of the Neo-Lamarckian theory of Evolution. + + +A Mechanico-Physiological Theory of Organic Evolution. By Carl von +Naegeli. Translated by V. A. Clark and F. A. Waugh. Price, cloth, 60c; +paper, 30c net. + + A synopsis of his great work on evolution. + + +Darwin and After Darwin. An exposition of the Darwinian Theory and a +Discussion of Post-Darwinian Questions. By George J. Romanes. 3 vols. +Price, $4.00 net. + +Part I. The Darwinian Theory. Price, cloth, $2.00 net. + +Part II. Post-Darwinian Questions: Heredity and Utility. Price, cloth, +$1.50 net. + +Part III. Post-Darwinian Questions. Isolation and Physiological +Selection. Price, cloth, $1.00 net. + + +An Examination of Weismannism. By George J. Romanes. Price, cloth, +$1.00 net; paper, 40c net. + + "The best criticism of the subject in our language."--_The + Outlook._ + + +On Germinal Selection. By August Weismann. Translated by T. J. +McCormack. Price, paper, 30c net. + + +The Rise of Man. A Sketch of the Origin of the Human Race. By Paul +Carus. Pages, 97; illustrated. Boards, cloth back, 75c net. + + +The Scope and Content of the Science of Anthropology. By Juul +Dieserud. Pages, 200; cloth, gilt top, $2.00 net. + + "The science of Anthropology," according to Topinard, "is that + branch of natural history which treats of man, and the races of + men." + + +Experiments on the Generation of Insects. By Francesco Redi. +Translated from the Italian edition of 1688, by Mab Bigelow. +Illustrated. Cloth, $2.00 net. + + This book may be counted as one of the classics of the theory of + evolution. + + +Ants and Some Other Insects. An Inquiry into the Psychic Powers of +these Animals, with an Appendix on the peculiarities of their Olfactory +Sense. By August Forel. Translated by William M. Wheeler. Price, +$1.00 net; paper, 55c net. + + +Plant Breeding. Comments on the Experiments of Nilsson and Burbank. By +Hugo de Vries. Pages, xv, 360. Illustrated with 114 half-tone plates +from nature. Printed on fine paper, in large type. Cloth, gilt top. +Price, $1.50 net. + + A scientific book in simple language. Intensely interesting as well + as instructive. Of special value to every botanist, horticulturist + and farmer. + + +Species and Varieties, Their Origin by Mutation. Lectures delivered at +the University of California by Hugo de Vries, Professor of Botany in +the University of Amsterdam. Pages, xviii, 847. Cloth, gilt top, $5.00 +net. + + +The Mutation Theory. Experiments and Observations on the Origin of +Species in the Vegetable Kingdom. 2 vols. Numerous illustrations, +colored plates. By Hugo de Vries. Translated by Prof. A. B. Farmer +and A. D. Darbishire. Cloth, per volume, $4.00. + + This is de Vries' great book on a new explanation of the evolution + theory, accounting for the formation of species not by the struggle + for existence but by mutation. + + +Intracellular Pangenesis. Including a paper on Fertilization and +Hybridization. By Hugo de Vries. Translated from the German by C. +Stuart Gager. Cloth, $3.00 net. + + This is de Vries' first important book. It is not very large, but + ought to be read by all students of botany, and also by those who + are interested in the theory of evolution. + + +On Orthogenesis and the Impotence of Natural Selection in +Species-Formation. By Th. Eimer. Translated by T. J. McCormack. +Price, paper, 30c net. + + Another critic of Darwin who claims that organisms develop through + transmission of acquired characters. + + +On the Inheritance of Acquired Characters. By Eugenio Rignano. +Translated by Basil C. H. Harvey. With an Appendix "On the Mnemonic +Origin and Nature of Affective Tendencies." Cloth, $3.00 net. + + Rignano calls his theory "centro-epigenesis" and is greatly + influenced by Weismann. + + +On Double Consciousness. Studies in Experimental Psychology. By +Alfred Binet. Third edition. Pages, 93. Cloth, 50c net; paper, 20c +net. + + "A most valuable contribution to this important subject which none + of its students can afford to leave unread."--_Public Opinion._ + + +The Psychic Life of Micro-Organisms. By Alfred Binet. Authorized +translation. Pages, xii, 120. Cloth, 75c net; paper, 30c net. + + "He fortifies his theory by such a wealth of exact observation and + experiments that the reader who follows his demonstration carefully + can hardly fail of conviction."--_New York Tribune._ + + +The Psychology of Reasoning. By Alfred Binet. Translated from the +second French edition by Adam Gowans Whyte, B.Sc. Pages, 191. Cloth, +75c net; paper, 30c net. + + "Like everything that Dr. Binet writes, the subject is stated and + expounded lucidly."--_The Lancet._ + + +The Diseases of Personality. By Theodule Ribot. Authorized +translation. Fourth edition. Pages, 157. Cloth, 75c net; paper, 30c. + + Contents: Introduction, Consciousness; Organic Disorders; Affective + Disorders; Diseases of the Intellect; Dissolution of Personality. + + +The Diseases of the Will. By Theodule Ribot. Authorized translation. +Third edition. Pages, vi, 121. Cloth, 75c net; paper, 30c net. + + Contains chapters on impairments of the will and of voluntary + attention, the realm of caprices, and extinction of the will. + + +Essay on the Creative Imagination. By Theodule Ribot. Translated +from the French by A. H. N. Baron, Fellow in Clark University. Cloth, +gilt top. Pages, 357. $1.75 net. + + The motor nature of the constructive imagination. + + +The Psychology of Attention. By Theodule Ribot, Professor in the +College de France and editor of the "Revue Philosophique." Fifth and +revised edition. Authorized translation. Pages, 121. Cloth, 75c net; +paper, 30c net. + + Contents: Spontaneous or Natural Attention; Voluntary or Artificial + Attention; Morbid States of Attention. + + +The Diseases of Memory. By Theodule Ribot. Cloth, $1.50 net. + + +Memory. Lectures on the Specific Energies of the Nervous System. By +Ewald Hering. Fourth edition, containing an additional chapter on the +Theory of Nerve Activity. Cloth, $1.00 net. + + +The Analysis of Sensations and the Relation of the Physical to the +Psychical. By Ernst Mach, Emeritus Professor in the University of +Vienna. Translated by C. M. Williams. Third edition revised and +supplemented from the fifth German edition by Sydney Waterlow, M.A. +Pages, xvi, 380. Cuts, 37. Cloth, $1.50 net. + + +Popular Science Lectures. By Ernst Mach, Professor in the University +of Vienna. Translated from the German by T. J. McCormack. Third +edition. Pages, 415. Cloth, gilt top, $1.50 net; paper, 60c net. + + A portrayal of the methods and spirit of science, in lectures on + mechanics, sound, light, electricity, the conservation of energy, + philosophy and education. + + +Man a Machine. By Julien Offray De La Mettrie. Including Frederick +the Great's Eulogy on La Mettrie and Extracts from La Mettrie's "Natural +History of the Soul." Translated, with notes, by Gertrude Carman +Bussey. French-English edition. With a portrait of La Mettrie. Pages, +226. Cloth, $2.00 net. + + La Mettrie was the most extreme writer among the earliest French + materialists. His doctrine is an extension to man of Descartes' + doctrine that animals are automata. + + + + +PORTRAITS + +Philosophical and Psychological Portrait Series + + +Printed on large paper (11 x 14) with tint and platemark. Many of them +are reproduced from rare paintings, engravings, or original photographs. +They are suitable for framing and hanging in public and private +libraries, laboratories, seminaries, recitation and lecture rooms, and +will be of interest to all concerned in education and general culture. + + +PHILOSOPHICAL + +Pythagoras +Socrates +Plato +Aristotle +Epictetus +Thomas Aquinas +St. Augustine +Averrhoes +Duns Scotus +Giordano Bruno +Bacon +Hobbes +Descartes +Malebranche +Herbert Spencer +Schelling +Spinoza +Locke +Berkeley +Hume +Montesquieu +Voltaire +D'Alembert +Condillac +Diderot +Rousseau +Leibniz +Wolff +Kant +Fichte +Hegel +Schleiermacher +Schopenhauer +Herbart +Feuerbach +Lotze +Reid +Dugald Stewart +Sir W. Hamilton +Cousin +Comte +Rosmini +J. Stuart Mill + + +PSYCHOLOGICAL + +Cabanis +Maine de Biran +Beneke +E. H. Weber +Fechner +Helmholtz +Wundt +Hering +G. T. Ladd +Aubert +Mach +Stumpf +Exner +Steinthal +Bain +Sully +Ward +C. L. Morgan +Romanes +Paul Janet +Ribot +Taine +Fouillee +Binet +G. Stanley Hall + + +PRICES: + +Philosophical and Psychological Portrait Series. + + 68 portraits on plate paper, $7.50 per set net. On Japanese vellum, + $12.50 per set net. + +Philosophical Portrait Series. + + No. 100. 43 portraits on plate paper, $6.25 per set net. + + No. 100a. 43 portraits on Japanese vellum, $8.75 per set net. + + Single portraits on American plate, 25c net. + + Single portraits on Japanese vellum, 35c net. + + +Psychological Portrait Series. + + No. 101. 25 portraits on plate paper, $3.75 net. + + No. 101a. 25 portraits on Japanese vellum, $5.00 net. + + Single portraits on American plate, 25c net. + + Single portraits on Japanese vellum, 35c net. + + +Framing Portrait of Hugo de Vries. + + Platino finish. 10" x 12", unmounted, $1.00 net. + + +Framing Portrait of William James. + + Printed on Japan paper. 11" x 14", $1.00. + + +Portraits of Eminent Mathematicians + +Three portfolios edited by David Eugene Smith, Professor of Mathematics +in Teachers' College, Columbia University, New York. + +In response to a widespread demand from those interested in mathematics +and the history of education, Professor Smith has edited three +portfolios of the portraits of some of the most eminent of the world's +contributors to the mathematical sciences. Accompanying each portrait is +a brief biographical sketch, with occasional notes of interest +concerning the artist represented. The pictures are of a size that +allows for framing (11" x 14"), it being the hope that a new interest in +mathematics may be aroused through the decoration of classrooms by the +portraits of those who helped to create the science. + +Portfolio No. 1.--Twelve great mathematicians down to 1700 A.D.: Thales, +Pythagorus, Euclid, Archimedes, Leonardo of Pisa, Cardan, Vieta, Napier, +Descartes, Fermat, Newton, Leibniz. + +Portfolio No. 2.--The most eminent founders and promotors of the +infinitesimal calculus: Cavallieri, Johann and Jakob Bernoulli, Pascal, +L'Hopital, Barrow, Laplace, Lagrange, Euler, Gauss, Monge, and Niccolo +Tartaglia. + +Portfolio No. 3--Eight portraits selected from the two former +portfolios, especially adapted for high schools and academies, +comprising portraits of + + Thales--with whom began the study of scientific geometry; + + Pythagoras--who proved the proposition of the square on the + hypotenuse; + + Euclid--whose Elements of Geometry form the basis of all modern + text-books; + + Archimedes--whose treatment of the circle, cone, cylinder and sphere + influences our work today; + + Descartes--to whom we are indebted for the graphic algebra in our + high schools; + + Newton--who generalized the binomial theorem and invented the + calculus; + + Napier--who invented logarithms and contributed to trigonometry; + + Pascal--who discovered the "Mystic Hexagram" at the age of sixteen. + + +Portraits of Mathematicians, Part I. + + No. 102. 12 portraits on American plate paper, $3.00 net. + + No. 102a. 12 portraits on Japanese vellum, $5.00 net. + + Single portraits, American plate, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +Portraits of Mathematicians, Part II. + + No. 103. 12 portraits on American plate paper, $3.00 net. + + No. 103a. 12 portraits on Japanese vellum, $5.00 net. + + Single portraits, American plate paper, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +Portraits of Mathematicians, High School Portfolio. + + Eight portraits selected from the two preceding portfolios. + + No. 104. 8 portraits on American plate paper, $2.00 net. + + No. 104a. 8 portraits on Japanese vellum, $3.50 net. + + Single portraits, American plate paper, 35c net. + + Single portraits, Japanese vellum, 50c net. + + +_For Purchasers who may prefer not to frame the Portraits, a neat +Portfolio can be supplied at an extra cost of $1.00._ + + + + + * * * * * + + + + +Transcriber's note: + + +The following typographical errors were correctred. + + |Page |Error |Correction | + |10 |dicussion |discussion | + |45 |thoughout |throughout | + |229 |pyschological |psychological | + +The following inconsistent hyphenations were changed. + + |Page |Original |Changed to | + |34 |inter-crossing |intercrossing | + |46 |re-appear |reappear | + |123 |re-act |react | + |132 |eye-lid |eyelid | + |216 |lifetimes |life-times | + |217 |lifetime |life-time | + |317 |threefold |three-fold | + +The following inconsistent hyphenations were not changed. + + "somatoplasm" (3 instances) and "somato-plasm" (2 instances) + "twofold" (2) and "two-fold" (1) + "interaction" (1) and "inter-action" (1) + "supernatural" (1) and "super-natural" (1) + +Other changes: + + Page 16 Footnote 10 - double quotes around "acceleration" and + "retardation" changed to single quotes. A double quote inserted at + the end. + + In the Index - Entries "On Truth" and "Orang-utan, teeth of" moved + from under "M" to under "O". + + + +***END OF THE PROJECT GUTENBERG EBOOK DARWIN, AND AFTER DARWIN, VOLUME II +(OF 3)*** + + +******* This file should be named 37759.txt or 37759.zip ******* + + +This and all associated files of various formats will be found in: +http://www.gutenberg.org/dirs/3/7/7/5/37759 + + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://www.gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS', WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.gutenberg.org/fundraising/pglaf. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://www.gutenberg.org/about/contact + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://www.gutenberg.org/fundraising/donate + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: +http://www.gutenberg.org/fundraising/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. + diff --git a/37759.zip b/37759.zip Binary files differnew file mode 100644 index 0000000..fc061a2 --- /dev/null +++ b/37759.zip diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..272a67c --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #37759 (https://www.gutenberg.org/ebooks/37759) |
