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+The Project Gutenberg EBook of Are the Effects of Use and Disuse Inherited?, by
+William Platt Ball
+
+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
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+
+Title: Are the Effects of Use and Disuse Inherited?
+       An Examination of the View Held by Spencer and Darwin
+
+Author: William Platt Ball
+
+Release Date: August 26, 2008 [EBook #26438]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE EFFECTS OF USE AND DISUSE ***
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+
+ _NATURE SERIES_
+
+
+               ARE THE EFFECTS OF USE AND
+                    DISUSE INHERITED?
+
+           _AN EXAMINATION OF THE VIEW HELD BY
+                   SPENCER AND DARWIN_
+
+
+                           BY
+                   WILLIAM PLATT BALL
+
+
+                         LONDON
+                    MACMILLAN AND CO.
+                      AND NEW YORK
+                          1890
+
+ _The Right of Translation and Reproduction is Reserved_
+
+
+
+
+ RICHARD CLAY AND SONS, LIMITED,
+       LONDON AND BUNGAY.
+
+
+
+
+PREFACE.
+
+
+My warmest thanks are due to Mr. Francis Darwin, to Mr. E. B. Poulton
+(whose interest in the subject here discussed is shown by his share in
+the translation of Weismann's _Essays on Heredity_), and to Professor
+Romanes, for the help afforded by their kindly suggestions and
+criticisms, and for the advice and recommendation under which this essay
+is now published. Encouragement from Mr. Francis Darwin is to me the
+more precious, and the more worthy of grateful recognition, from the
+fact that my general conclusion that acquired characters are _not_
+inherited is at variance with the opinion of his revered father, who
+aided his great theory by the retention of some remains of Lamarck's
+doctrine of the inherited effect of habit. I feel as if the son, as
+representative of his great progenitor, were carrying out the idea of an
+appreciative editor who writes to me: "We must say that if Darwin were
+still alive, he would find your arguments of great weight, and
+undoubtedly would give to them the serious consideration which they
+deserve." I hope, then, that I may be acquitted of undue presumption in
+opposing a view sanctioned by the author of the _Origin of Species_, but
+already stoutly questioned and firmly rejected by such followers of his
+as Weismann, Wallace, Poulton, Ray Lankester, and others, to say nothing
+of its practical rejection by so great an authority on heredity as
+Francis Galton.
+
+The sociological importance of the subject has already been insisted on
+in emphatic terms by Mr. Herbert Spencer, and this importance may be
+even greater than he imagined.
+
+Civilization largely sets aside the harsh but ultimately salutary action
+of the great law of Natural Selection without providing an efficient
+substitute for preventing degeneracy. The substitute on which moralists
+and legislators rely--if they think on the matter at all--is the
+cumulative inheritance of the beneficial effects of education, training,
+habits, institutions, and so forth--the inheritance, in short, of
+acquired characters, or of the effects of use and disuse. If this
+substitute is but a broken reed, then the deeper thinkers who gradually
+teach the teachers of the people, and ultimately even influence the
+legislators and moralists, must found their systems of morality and
+their criticisms of social and political laws and institutions and
+customs and ideas on the basis of the Darwinian law rather than on that
+of Lamarck.
+
+Looking forward to the hope that the human race may become consciously
+and increasingly master of itself and of its destiny, and recognizing
+the Darwinian principle of the selection of the fittest as the _only_
+means of preventing the moral and physical degeneracy which, like an
+internal dry rot, has hitherto been the besetting danger of all
+civilizations, I desire that the thinkers who mould the opinions of
+mankind shall not be led astray from the true path of enduring progress
+and happiness by reliance on fallacious beliefs which will not bear
+examination. Such, at least, is the feeling or motive which has prompted
+me to devote much time and thought to a difficult but important inquiry
+in a debatable region of inference and conjecture, where (I am afraid)
+evidence on either side can never be absolutely conclusive, and where,
+especially, the absolute demonstration of a universal negative cannot
+reasonably be expected.
+
+
+
+
+CONTENTS.
+
+
+                                                                PAGE
+ PREFACE                                                           v
+
+ IMPORTANCE AND BEARING OF THE INQUIRY                             1
+
+ SPENCER'S EXAMPLES AND ARGUMENTS                               6-44
+   DIMINUTION OF THE JAWS                                          6
+   DIMINISHED BITING MUSCLES OF LAP-DOGS                          12
+   CROWDED TEETH                                                  14
+   BLIND CAVE-CRABS                                               17
+   NO CONCOMITANT VARIATION FROM CONCOMITANT DISUSE               17
+   THE GIRAFFE, AND NECESSITY FOR CONCOMITANT VARIATION           18
+   ALLEGED RUINOUS EFFECTS OF NATURAL SELECTION                   23
+   ADVERSE CASE OF NEUTER INSECTS                                 24
+   AESTHETIC FACULTIES                                             29
+   LACK OF EVIDENCE                                               34
+   INHERITED EPILEPSY IN GUINEA-PIGS                              35
+   INHERITED INSANITY AND NERVOUS DISORDERS                       36
+   INDIVIDUAL AND TRANSMISSIBLE TYPE NOT MODIFIED ALIKE           40
+
+ DARWIN'S EXAMPLES                                            45-100
+   REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS                      49
+   DROOPING EARS AND DETERIORATED INSTINCTS                       53
+   WINGS AND LEGS OF DUCKS AND FOWLS                              55
+   PIGEONS' WINGS                                                 62
+   SHORTENED BREAST-BONE IN PIGEONS                               64
+   SHORTENED FEET IN PIGEONS                                      70
+   SHORTENED LEGS OF RABBITS                                      70
+   BLIND CAVE-ANIMALS                                             72
+   INHERITED HABITS                                               73
+   TAMENESS OF RABBITS                                            76
+   MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION              82
+   SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE       83
+   INFERIORITY OF SENSES IN EUROPEANS                             85
+   SHORT-SIGHT IN WATCHMAKERS AND ENGRAVERS                       85
+   LARGER HANDS OF LABOURERS' INFANTS                             87
+   THICKENED SOLE IN INFANTS                                      88
+   A SOURCE OF MENTAL CONFUSION                                   91
+   WEAKNESS OF USE-INHERITANCE                                    94
+
+ INHERITED INJURIES                                          101-118
+   INHERITED MUTILATIONS                                         101
+   THE MOTMOT'S TAIL                                             110
+   OTHER INHERITED INJURIES MENTIONED BY DARWIN                  111
+   QUASI-INHERITANCE                                             116
+
+ MISCELLANEOUS CONSIDERATIONS                                119-143
+   TRUE RELATION OF PARENTS AND OFFSPRING                        119
+   INVERSE INHERITANCE                                           123
+   EARLY ORIGIN OF THE OVA                                       124
+   MARKED EFFECTS OF USE AND DISUSE ON THE INDIVIDUAL            126
+   WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE?               127
+   USE-INHERITANCE AN EVIL                                       128
+   VARIED EFFECTS OF USE AND DISUSE                              134
+   USE-INHERITANCE IMPLIES PANGENESIS                            137
+   PANGENESIS IMPROBABLE                                         138
+   SPENCER'S EXPLANATION OF USE-INHERITANCE                      141
+
+ CONCLUSIONS                                                 144-156
+   USE-INHERITANCE DISCREDITED AS UNNECESSARY, UNPROVEN,
+       AND IMPROBABLE                                            144
+   MODERN RELIANCE ON USE-INHERITANCE MISPLACED                  145
+
+
+
+
+ARE THE EFFECTS OF USE AND DISUSE INHERITED?
+
+
+
+
+IMPORTANCE AND BEARING OF THE INQUIRY.
+
+
+The question whether the effects of use and disuse are inherited, or, in
+other words, whether acquired characters are hereditary, is of
+considerable interest to the general student of evolution; but it is, or
+should be, a matter of far deeper interest to the thoughtful
+philanthropist who desires to ensure the permanent welfare and happiness
+of the human race. So profoundly important, in fact, are the moral,
+social, and political conclusions that depend on the answer to this
+inquiry, that, as Mr. Herbert Spencer rightly says, it "demands, beyond
+all other questions whatsoever, the attention of scientific men."
+
+It is obvious that we can produce important changes in the individual.
+We can, for example, improve his muscles by athletics, and his brain by
+education. The use of organs enlarges and strengthens them; the disuse
+of parts or faculties weakens them. And so great is the power of habit
+that it is proverbially spoken of as "second nature." It is thus certain
+that we can modify the individual. We can strengthen (or weaken) his
+body; we can improve (or deteriorate) his intellect, his habits, his
+morals. But there remains the still more important question which we are
+about to consider. Will such modifications be inherited by the offspring
+of the modified individual? Does individual improvement transmit itself
+to descendants independently of personal teaching and example? Have
+artificially produced changes of structure or habit any inherent
+tendency to become congenitally transmissible and to be converted in
+time into fixed traits of constitution or character? Can the
+philanthropist rely on such a tendency as a hopeful factor in the
+evolution of mankind?--the only sound and stable basis of a higher and
+happier state of things being, as he knows or ought to know, the innate
+and constitutionally-fixed improvement of the race as a whole. If
+acquired modifications are impressed on the offspring and on the race,
+the systematic moral training of individuals will in time produce a
+constitutionally moral race, and we may hope to improve mankind even in
+defiance of the unnatural selection by which a spurious but highly
+popular philanthropy would systematically favour the survival of the
+unfittest and the rapid multiplication of the worst. But if acquired
+modifications do not tend to be transmitted, if the use or disuse of
+organs or faculties does not similarly affect posterity by inheritance,
+then it is evident that no innate improvement in the race can take place
+without the aid of natural or artificial selection.
+
+Herbert Spencer maintains that the effects of use and disuse _are_
+inherited in kind, and in his _Factors of Organic Evolution_[1] he has
+supported his contention with a selection of facts and reasonings which
+I shall have the temerity to examine and criticize. Darwin also held the
+same view, though not so strongly. And here, to prevent
+misunderstanding, I may say that the admiration and reverence and
+gratitude due to Darwin ought not to be allowed to interfere in the
+slightest degree with the freest criticism of his conclusions. To
+perfect his work by the correction of really extraneous errors is as
+much a sacred duty as to study and apply the great truths he has taught.
+
+
+FOOTNOTES:
+
+[1] Which originally appeared in the _Nineteenth Century_ for April and
+May, 1886.
+
+
+
+
+SPENCER'S EXAMPLES AND ARGUMENTS.
+
+
+DIMINUTION OF THE JAWS IN CIVILIZED RACES.
+
+Mr. Spencer verified this by comparing English jaws with Australian and
+Negro jaws at the College of Surgeons.[2] He maintains that the
+diminution of the jaw in civilized races can _only_ have been brought
+about by inheritance of the effects of lessened use. But if English jaws
+are lighter and thinner than those of Australians and Negroes, so too is
+the rest of the skull. As the diminution in the weight and thickness of
+the walls of the cranium cannot well be ascribed to disuse, it must be
+attributed to some other cause; and this cause may have affected the jaw
+also. Cessation of the process by which natural selection[3] favoured
+strong thick bones during ages of brutal violence might bring about a
+change in this direction. Lightness of structure, facilitating agility
+and being economical of material, would also be favoured by natural
+selection so far as strength was not too seriously diminished.
+
+Sexual selection powerfully affects the human face, and so must affect
+the jaws--as is shown by the differences between male and female jaws,
+and by the relative lightness and smallness of the latter, especially in
+the higher races. Human preference, both sexual and social, would tend
+to eliminate huge jaws and ferocious teeth when these were no longer
+needed as weapons of war or organs of prehension, &c. We can hardly
+assume that the lower half of the face is specially exempt from the
+influence of natural and sexual selection; and the effects of these
+undoubted factors of evolution must be fully considered before we are
+entitled to call in the aid of a factor whose existence is questioned.
+
+After allowing for lost teeth and the consequent alveolar absorption,
+and for a reduction proportional to that shown in the rest of the skull,
+the difference in average weight in fifty European and fourteen
+Australian male jaws at the College of Surgeons turned out to be less
+than a fifth of an ounce, or about 5 per cent. This slight reduction may
+be much more than accounted for by such causes as disuse in the
+individual, human preference setting back the teeth, and partial
+transference of the much more marked diminution seen in female jaws.
+There is apparently no room for accumulated _inherited_ effects of
+ancestral disuse. The number of jaws is small, indeed; but weighing them
+is at least more decisive than Mr. Spencer's mere inspection.
+
+The differences between Anglo-Saxon male jaws and Australian and
+Tasmanian jaws are most easily explained as effects of human preference
+and natural selection. We can hardly suppose that disuse would maintain
+or develop the projecting chin, increase its perpendicular height till
+the jaw is deepest and strongest at its extremity, evolve a side flange,
+and enlarge the upper jaw-bone to form part of a more prominent nose,
+while drawing back the savagely obtrusive teeth and lips to a more
+pleasing and subdued position of retirement and of humanized beauty. If
+human preference and natural selection caused some of these differences,
+why are they incompetent to effect changes in the direction of a
+diminution of the jaw or teeth? And if use and disuse are the sole
+modifying agents in the case of the human jaw, why should men have any
+more chin than a gorilla or a dog?
+
+The excessive weight of the West African jaws at the College of Surgeons
+is partly _against_ Mr. Spencer's contention, unless he assumes that
+Guinea Negroes use their jaws far more than the Australians, a
+supposition which seems extremely improbable. The heavier skull and
+narrower molar teeth point however to other factors than increased use.
+
+The striking variability of the human jaw is strongly opposed to the
+idea of its being under the direct and dominant control of so uniform a
+cause as ancestral use and disuse. Mr. Spencer regards a variation of 1
+oz. as a large one, but I found that the English jaws in the College of
+Surgeons varied from 1.9 oz. to 4.3 oz. (or 5 oz. if lost teeth were
+allowed for); Australian jaws varied from 2 oz. to 4.5 oz. (with _no_
+lost teeth to allow for); while in Negro jaws the maximum rose to over
+5-1/2 oz.[4] In spite of disuse some European jaws were twice as heavy
+as the lightest Australian jaw, either absolutely or (in some cases)
+relatively to the cranium. The uniformity of change relied upon by Mr.
+Spencer is scarcely borne out by the facts so far as male jaws are
+concerned. The great reduction in the weight of _female_ jaws _and
+skulls_ evidently points to sexual selection and to panmixia under male
+protection.
+
+I think, on the whole, we must conclude that the human jaws do not
+afford satisfactory proof of the inheritance of the effects of use and
+disuse, inasmuch as the differences in their weight and shape and size
+can be more reasonably and consistently accounted for as the result of
+less disputable causes.
+
+
+DIMINISHED BITING MUSCLES OF LAP-DOGS.
+
+The next example, the reduced biting muscles, &c., of lap-dogs is also
+unsatisfactory as a proof of the inheritance of the effects of disuse;
+for the change can readily be accounted for without the introduction of
+such a factor. The previous natural selection of strong jaws and teeth
+and muscles is reversed. The conscious or unconscious selection of
+lap-dogs with the least tendency to bite would easily bring about a
+general enfeeblement of the whole biting apparatus--weakness of the
+parts concerned favouring harmlessness. Mr. Spencer maintains that the
+dwindling of the parts concerned in clenching the jaw is certainly not
+due to artificial selection because the modifications offer no
+appreciable external signs. Surely hard biting is sufficiently
+appreciable by the person bitten without any visual admeasurement of the
+masseter muscles or the zygomatic arches. Disuse during lifetime would
+also cause some amount of degeneracy; and I am not sure that Mr. Spencer
+is right in _entirely_ excluding economy of nutrition from the problem.
+Breeders would not over-feed these dogs; and the puppies that grew most
+rapidly would usually be favoured.
+
+
+CROWDED TEETH.
+
+The too closely-packed teeth in the "decreasing" jaws of modern men (p.
+13)[5] are also suggestive of other causes than use and disuse. Why is
+there not simultaneous variation in teeth and jaws, if disuse is the
+governing factor? Are we to suppose that the size of the human teeth is
+maintained by use at the same time that the jaws are being diminished by
+disuse? Mr. Spencer acknowledges that the crowding of bull-dogs' and
+lap-dogs' teeth is caused by the artificial selection of shortened jaws.
+If a similar change is really occurring in man, could it not be
+similarly explained by some factor, such as sexual selection, which
+might affect the outward appearance at the cost of less obvious defects
+or inconveniences?
+
+Mr. Spencer points to the decay of modern teeth as a sign or result of
+their being overcrowded through the diminution of the jaw by disuse.[6]
+But the teeth which are the most frequently overcrowded are the lower
+incisors. The upper incisors are less overcrowded, being commonly
+pressed outwards by the lower arc of teeth fitting inside them in
+biting. The lower incisors are correspondingly pressed inwards and
+closer together. Yet the upper incisors decay--or at least are
+extracted--about twenty times as frequently as the closely packed lower
+incisors.[7] Surely this must indicate that the cause of decay is not
+overcrowding.
+
+The lateness and irregularity of the wisdom teeth are sometimes
+supposed to indicate their gradual disappearance through want of room in
+a diminishing jaw. But a note on Tasmanian skulls in the _Catalogue of
+the College of Surgeons_ (p. 199) shows that this lateness and
+irregularity have been common among Tasmanians as well as among
+civilized races, so that the change can hardly be attributed to the
+effects of disuse under civilization.
+
+
+BLIND CAVE-CRABS.
+
+The cave-crabs which have lost their disused eyes but _not the disused
+eye-stalks_ appear to illustrate the effects of natural selection rather
+than of disuse. The loss of the exposed, sensitive, and
+worse-than-useless eye, would be a decided gain, while the disused
+eye-stalk, being no particular detriment to the crab, would be but
+slightly affected by natural selection, though open to the cumulative
+effects of disuse. The disused but better protected eyes of the blind
+cave-rat are still "of large size" (_Origin of Species_, p. 110).
+
+
+NO CONCOMITANT VARIATION FROM CONCOMITANT DISUSE.
+
+It is but fair to add that these instances of the cave-crab's eye-stalk
+and the closely-packed teeth are put forward by Mr. Spencer with the
+more immediate object of proving that there is "no concomitant
+variation in co-operative parts," even when "formed out of the same
+tissue, like the crab's eye and its peduncle" (pp. 12-14, 23, 33). It
+escapes his notice, however, that in two out of his three cases it is
+_disuse_, or _diminished use_, which fails to cause concomitant
+variation or proportionate variation.
+
+
+THE GIRAFFE, AND NECESSITY FOR CONCOMITANT VARIATION.
+
+Having unwittingly shown that lessened use of closely-connected and
+co-operative parts does not cause concomitant variation in these parts,
+Mr. Spencer concludes that the concomitant variation requisite for
+evolution can only be caused by altered degrees of use or disuse. He
+elaborately argues that the many co-ordinated modifications of parts
+necessitated by each important alteration in an animal are so complex
+that they cannot possibly be brought about except by the inherited
+effect of the use and disuse of the various parts concerned. He holds,
+for instance, that natural selection is inadequate to effect the
+numerous concomitant changes necessitated by such developments as that
+of the long neck of the giraffe. Darwin, however, on the contrary, holds
+that natural selection alone "would have sufficed for the production of
+this remarkable quadruped."[8] He is surprised at Mr. Spencer's view
+that natural selection can do so little in modifying the higher animals.
+Thus one of the chief arguments with which Mr. Spencer supports his
+theory is so poorly founded as to be rejected by a far greater authority
+on such subjects. All that is needed is that natural selection should
+preserve the tallest giraffes through times of famine by their being
+able to reach otherwise inaccessible stores of foliage. The continual
+variability of all parts of the higher animals gives scope for
+innumerable changes, and Nature is not in a hurry. Mr. Spencer, however,
+says that "the chances against any adequate readjustments fortuitously
+arising must be infinity to one." But he has also shown that altered
+degree of use does not cause the needed concomitant variation of
+co-operative parts. So the chances against a beneficial change in an
+animal must be, at a liberal estimate, infinity to two. Mr. Spencer, if
+he has proved anything, has proved that it is practically impossible
+that the giraffe can have acquired a long neck, or the elk its huge
+horns, or that any species has ever acquired any important modification.
+
+Mr. Wallace, in his _Darwinism_, answers Mr. Spencer by a collection of
+facts showing that "variation is the rule," that the range of variation
+in wild animals and plants is much greater than was supposed, and that
+"each part varies to a considerable extent independently" of other
+parts, so that "the materials constantly ready for natural selection to
+act upon are abundant in quantity and very varied in kind." While
+co-operative parts would often be more or less correlated, so that they
+would tend to vary together, coincident variation is not necessary. The
+lengthened wing might be gained in one generation, and the strengthened
+muscle at a subsequent period; the bird in the meanwhile drawing upon
+its surplus energy, aided (as I would suggest) by the strengthening
+effect of increased use in the individual. Seeing that artificial
+selection of complicated variations has modified animals in many points
+either simultaneously or by slow steps, as with otter-sheep, fancy
+pigeons, &c. (many of the characters thus obtained being clearly
+independent of use and disuse), natural selection must be credited with
+similar powers, and Mr. Wallace concludes that Mr. Spencer's
+insuperable difficulty is "wholly imaginary."
+
+The extract concerning a somewhat similar "class of difficulties," which
+Mr. Spencer quotes from his _Principles of Biology_, is faulty in its
+reasoning,[9] though legitimate in its conclusion concerning the
+increasing difficulty of evolution in proportion with the increasing
+number and complexity of faculties to be evolved. But this increasing
+difficulty of complex evolution is only overcome by _some_
+favourably-varying individuals and species--not by all. And as the
+difficulty increases we find neglect and decay of the less-needed
+faculties--as with domesticated animals and civilized men, who lose in
+one direction while they gain in another. The increasing difficulty of
+complex evolution by natural selection is no proof whatever of
+use-inheritance[10] except to those who confound difficulty with
+impossibility.
+
+
+ALLEGED RUINOUS EFFECTS OF NATURAL SELECTION.
+
+Mr. Spencer further contends that natural selection, by unduly
+developing specially advantageous modifications without the necessary
+but complex secondary modifications, would render the constitution of a
+variety "unworkable" (p. 23). But this seems hardly feasible, seeing
+that natural selection must continually favour the most workable
+constitutions, and will only preserve organisms in proportion as they
+combine general workableness with the special modification. On the other
+hand, according to Mr. Spencer himself, use-inheritance must often
+disturb the balance of the constitution. Thus it tends to make the jaws
+and teeth unworkable through the overcrowding and decay of the
+teeth--there being, as his illustrations show, no simultaneous or
+concomitant or proportional variation in relation to altered degree of
+use or disuse.
+
+
+ADVERSE CASE OF NEUTER INSECTS.
+
+Mr. Spencer also holds that most mental phenomena, especially where
+complex or social or moral, can only be explained as arising from
+use-inheritance, which becomes more and more important as a factor of
+evolution as we advance from the vegetable world and the lower grades of
+animal life to the more complex activities, tastes, and habits of the
+higher organizations (preface, and p. 74). But there happens to be a
+tolerably clear proof that such changes as the evolution of complicated
+structures and habits and social instincts _can_ take place
+independently of use-inheritance. The wonderful instincts of the working
+bees have apparently been evolved (at least in all their later social
+complications and developments) without the aid of use-inheritance--nay,
+in spite of its utmost opposition. Working bees, being infertile
+"neuters," cannot as a rule transmit their own modifications and habits.
+They are descended from countless generations of queen bees and drones,
+whose habits have been widely different from those of the workers, and
+whose structures are dissimilar in various respects. In many species of
+ants there are two, and in the leaf-cutting ants of Brazil there are
+_three_, kinds of neuters which differ from each other and from their
+male and female ancestors "to an almost incredible degree."[11] The
+soldier caste is distinguished from the workers by enormously large
+heads, very powerful mandibles, and "extraordinarily different"
+instincts. In the driver ant of West Africa one kind of neuter is three
+times the size of the other, and has jaws nearly five times as long. In
+another case "the workers of one caste alone carry a wonderful sort of
+shield on their heads." One of the three neuter classes in the
+leaf-cutting ants has a single eye in the midst of its forehead. In
+certain Mexican and Australian ants some of the neuters have huge
+spherical abdomens, which serve as living reservoirs of honey for the
+use of the community. In the equally wonderful case of the termites, or
+so-called "white ants" (which belong, however, to an entirely different
+order of insect from the ants and bees) the neuters are blind and
+wingless, and are divided into soldiers and workers, each class
+possessing the requisite instincts and structures adapting it for its
+tasks. Seeing that natural selection can form and maintain the various
+structures and the exceedingly complicated instincts of ants and bees
+and wasps and termites in direct defiance of the alleged tendency to
+use-inheritance, surely we may believe that natural selection,
+unopposed by use-inheritance, is equally competent for the work of
+complex or social or mental evolution in the many cases where the strong
+presumptive evidence cannot be rendered almost indisputable by the
+exceptional exclusion of the modified animal from the work of
+reproduction.
+
+Ants and bees seem to be capable of altering their habits and methods of
+action much as men do. Bees taken to Australia cease to store honey
+after a few years' experience of the mild winters. Whole communities of
+bees sometimes take to theft, and live by plundering hives, first
+killing the queen to create dismay among the workers. Slave ants attend
+devotedly to their captors, and fight against their own species. Forel
+reared an artificial ant-colony made up of five different and more or
+less hostile species. Why cannot a much more intelligent animal modify
+his habits far more rapidly and comprehensively without the aid of a
+factor which is clearly unnecessary in the case of the more intelligent
+of the social insects?
+
+
+AESTHETIC FACULTIES.
+
+The modern development of music and harmony (p. 19) is undeniable, but
+why could it only have been brought about by the help of the inheritance
+of the effects of use? Why are we to suppose that "minor traits" such as
+the "aesthetic perceptions" cannot have been evolved by natural selection
+(p. 20) or by sexual selection? Darwin holds that our musical faculties
+were developed by sexual preference long before the acquisition of
+speech. He believes that the "rhythms and cadences of oratory are
+derived from previously developed musical powers"--a conclusion "exactly
+opposite" to that arrived at by Mr. Spencer.[12] The emotional
+susceptibility to music, and the delicate perceptions needed for the
+higher branches of art, were apparently the work of natural and sexual
+selection in the long past. Civilization, with its leisure and wealth
+and accumulated knowledge, perfects human faculties by artificial
+cultivation, develops and combines means of enjoyment, and discovers
+unsuspected sources of interest and pleasure. The sense of harmony,
+modern as it seems to be, must have been a latent and indirect
+consequence of the development of the sense of hearing and of melody.
+Use, at least, could never have called it into existence. Nature favours
+and develops enjoyments to a certain extent, for they subserve
+self-preservation and sexual and social preference in innumerable ways.
+But modern aesthetic advance seems to be almost entirely due to the
+culture of latent abilities, the formation of complex associations, the
+selection and encouragement of talent, and the wide diffusion and
+imitation of the accumulated products of the well-cultivated genius of
+favourably varying individuals. The fact that uneducated persons do not
+enjoy the higher tastes, and the rapidity with which such tastes are
+acquired or professed, ought to be sufficient proof that modern culture
+is brought about by far swifter and more potent influences than
+use-inheritance. Neither would this hypothetical factor of evolution
+materially aid in explaining the many other rapid changes of habit
+brought about by education, custom, and the changed conditions of
+civilization generally. Powerful tastes--as is incontestably shown in
+the cases of alcohol and tobacco--lie latent for ages, and suddenly
+become manifest when suitable conditions arise. Every discovery, and
+each step in social and moral evolution, produces its wide-spreading
+train of consequences. I see no reason why use-inheritance need be
+credited with any share in the cumulative results of the invention of
+printing and the steam-engine and gunpowder, or of freedom and security
+under representative government, or of science and art and the partial
+emancipation of the mind of man from superstition, or of the innumerable
+other improvements or changes that take place under modern civilization.
+
+Mr. Spencer suggests an inquiry whether the greater powers possessed by
+eminent musicians were not mainly due to the inherited effect of the
+musical practice of their fathers (p. 19). But these great musicians
+inherited far more than their parents possessed. The excess of their
+powers beyond their parents' must surely be attributed to spontaneous
+variation; and who shall say that the rest was in any way due to
+use-inheritance? If, too, the superiority of geniuses proves
+use-inheritance, why should not the inferiority of the sons of geniuses
+prove the existence of a tendency which is the exact opposite of
+use-inheritance? But nobody collects facts concerning the degenerate
+branches of musical families. Only the favourably varying branches are
+noticed, and a general impression of rapid evolution of talent is thus
+produced. Such cases might be explained, too, by the facts that musical
+faculty is strong in both sexes, that musical families associate
+together, and that the more gifted members may intermarry. Great
+musicians are often astonishingly precocious. Meyerbeer "played
+brilliantly" at the age of six. Mozart played beautifully at four. Are
+we to suppose that the effect of the _adult_ practice of parents was
+inherited at this early age? If use-inheritance was not necessary in the
+case of Handel, whose father was a surgeon, why is it needed to account
+for Bach?
+
+
+LACK OF EVIDENCE.
+
+The "direct proofs" of use-inheritance are not as plentiful as might be
+desired, it appears (pp. 24-28). This acknowledged "lack of recognized
+evidence" is indeed the weakest feature in the case, though Mr. Spencer
+would fain attribute this lack of direct proof to insufficient
+investigation and to the inconspicuous nature of the inheritance of the
+modification. But there is an almost endless abundance of conspicuous
+examples of the effects of use and disuse in the individual. How is it
+that the subsequent inheritance of these effects has not been more
+satisfactorily observed and investigated? Horse-breeders and others
+could profit by such a tendency, and one cannot help suspecting that the
+reason they ignore it must be its practical inefficacy, arising probably
+from its weakness, its obscurity and uncertainty or its non-existence.
+
+
+INHERITED EPILEPSY IN GUINEA-PIGS.
+
+Brown-Sequard's discovery that an epileptic tendency artificially
+produced by mutilating the nervous system of a guinea-pig is
+occasionally inherited may be a fact of "considerable weight," or on the
+other hand it may be entirely irrelevant. Cases of this kind strike one
+as peculiar exceptions rather than as examples of a general rule or law.
+They seem to show that certain morbid conditions may occasionally affect
+both the individual and the reproductive elements or transmissible type
+in a similar manner; but then we also know that such prompt and complete
+transmission of an artificial modification is widely different from the
+usual rule. Exceptional cases require exceptional explanations, and are
+scarcely good examples of the effect of a general tendency which in
+almost all other cases is so inconspicuous in its immediate effects.
+Further remarks on this inherited epilepsy can be most conveniently
+introduced later on in connection with Darwin's explanation of the
+inherited mutilation which it usually accompanies, but which Mr. Spencer
+does not mention.
+
+
+INHERITED INSANITY AND NERVOUS DISORDERS.
+
+Mr. Spencer infers that, because insanity is usually hereditary, and
+insanity can be artificially produced by various excesses, therefore
+this artificially-produced insanity must also be hereditary (p. 28).
+Direct evidence of this conclusion would be better than a mere inference
+which may beg the very question at issue. That the liability to insanity
+commonly runs in families is no proof that strictly non-inherited
+insanity will subsequently become hereditary. I think that theories
+should be based on facts rather than facts on theories, especially when
+those facts are to be the basis or proof of a further theory.
+
+Mr. Spencer also points out that he finds among physicians "the belief
+that nervous disorders of a less severe kind are inheritable"--a general
+belief which does not necessarily include the transmission of purely
+artificially-produced disorders, and so misses the point which is really
+at issue. He proceeds, however, to state more definitely that "men who
+have prostrated their nervous systems by prolonged overwork or in some
+other way, have children more or less prone to nervousness." The
+following observations will, I think, warrant at least a suspension of
+judgment concerning this particular form of use-inheritance.
+
+(1) The nervousness is seen in the _children_ at an early age, although
+the nervous prostration from which it is supposed to be derived
+obviously occurs in the parent at a much later period of life. This
+change in time is contrary to the rule of inheritance at corresponding
+periods; and, together with the unusual promptness and comparative
+completeness of the inheritance, it may indicate a special injury or
+deterioration of the reproductive elements rather than true inheritance.
+The healthy brain of early life has failed to transmit its robust
+condition. Is use-inheritance, then, only effective for evil? Does it
+only transfer the newly-acquired weakness, and not the previous
+long-continued vigour?
+
+(2) Members of nervous families would be liable to suffer from nervous
+prostration, and by the ordinary law of heredity alone would transmit
+nervousness to their children.
+
+(3) The shattered nerves or insanity resulting from alcoholic and other
+excesses, or from overwork or trouble, are evidently signs of a grave
+constitutional injury which may react upon the reproductive elements
+nourished and developed in that ruined constitution. The deterioration
+in parent and child may often display itself in the same organs--those
+probably which are hereditarily weakest. Acquired diseases or disorders
+thus appear to be transmitted, when all that was conveyed to the
+offspring was the exciting cause of a lowered vitality or disordered
+action, together with the ancestral liability to such diseases under
+such conditions.
+
+(4) Francis Galton says that "it is hard to find evidence of the power
+of the personal structure to react upon the sexual elements, that is not
+open to serious objection." Some of the cases of apparent inheritance he
+regards as coincidence of effect. Thus "the fact that a drunkard will
+often have imbecile children, although his offspring previous to his
+taking to drink were healthy," is an "instance of simultaneous action,"
+and not of true inheritance. "The alcohol pervades his tissues, and, of
+course, affects the germinal matter in the sexual elements as much as it
+does that in his own structural cells, which have led to an alteration
+in the quality of his own nerves. Exactly the same must occur in the
+case of many constitutional diseases that have been acquired by
+long-continued irregular habits."[13]
+
+
+INDIVIDUAL AND TRANSMISSIBLE TYPE NOT MODIFIED ALIKE BY THE DIRECT
+EFFECT OF CHANGED HABITS OR CONDITIONS.
+
+Mr. Spencer finds it hard to believe that the modifications conveyed to
+offspring are not identical in tendency with the changes effected in the
+parent by altered use or habit (pp. 23-25, 34). But it is perfectly
+certain that the two sets of effects do not necessarily correspond. The
+effect of changed habits or conditions on the individual is often very
+far from coinciding with the effects on the reproductive elements or
+the transmissible type. The reproductive system is "extremely
+sensitive" to very slight changes, and is often powerfully affected by
+circumstances which otherwise have little effect on the individual
+(_Origin of Species_, p. 7). Various animals and plants become sterile
+when domesticated or supplied with too much nourishment. The native
+Tasmanians have already become extinct from sterility caused by greatly
+changed diet and habits. If, as Mr. Spencer teaches, continued culture
+and brain-work will in time produce lessened fertility or comparative
+sterility, we may yet have to be careful that intellectual development
+does not become a species of suicide, and that the culture of the race
+does not mean its extinction--or at least the extinction of those most
+susceptible of culture.
+
+The reproductive elements are also disturbed and modified in innumerable
+minor ways. Changed conditions or habits tend to produce a general
+"plasticity" of type, the "indefinite variability" thus caused being
+apparently irrelevant to the change, if any, in the individual.[14] A
+vast number of variations of structure have certainly arisen
+independently of similar parental modification as the preliminary.
+Whatever first caused these "spontaneous" congenital variations affected
+the reproductive elements quite differently from the individual. "When a
+new peculiarity first appears we can never predict whether it will be
+inherited." Many varieties of plants only keep true from shoots, and not
+from seed, which is by no means acted on in the same way as the
+individual plant. Seeing that such plants have _two_ reproductive
+types, both constant, it is evident that these cannot both be modified
+in the same way as the parent is modified. Many parental modifications
+of structure and habit are certainly not conveyed to neuter ants and
+bees; other modifications, which are not seen in the parents, being
+conveyed instead. Many other circumstances tend to show that the
+individual and the transmissible type are independent of each other so
+far as modifications of parts are concerned.
+
+It may seem natural to expect the transmission of an enlarged muscle or
+a cultivated brain, but, on the other hand, why should it be
+unreasonable to expect that a modification which was non-congenital in
+origin should still remain non-congenital? Why should the
+non-transmission of that which was not transmitted be surprising?
+
+Mr. Spencer thinks that the non-transmission of acquired modifications
+is incongruous with the great fact of atavism. But the great law of the
+inheritance of that which is a development of the transmissible type
+does not necessarily imply the inheritance of modifications acquired by
+the individual. Because English children may inherit blue eyes and
+flaxen hair from their Anglo-Saxon ancestors, it by no means follows
+that an Englishman must inherit his father's sunburnt complexion or
+smooth-shaven face. Of course atavism ultimately adopts many instances
+of revolt against its sway. But to assume that these changes of type
+_follow_ the personal change rather than cause it, is to assume the
+whole question at issue. That like begets like is true as a broad
+principle, but it has many exceptions, and the non-heredity of acquired
+characters may be one of them.
+
+
+FOOTNOTES:
+
+[2] _Principles of Biology_, Sec. 166, footnote. The English jaws are
+somewhat lighter than the Australian jaws, though I could not undertake
+to affirm that they are really shorter and smaller. In the typical
+skulls depicted on p. 68 of the official guide to the mammalian
+galleries at South Kensington, the typical Caucasian jaw is very much
+larger than the Tasmanian jaw, although the repulsively obtrusive teeth
+of the latter convey the contrary idea to the imagination. Mr. Spencer's
+assumption that the ancient Britons had large jaws appears to me
+erroneous. (See Professor Rolleston's _Scientific Papers and Addresses_,
+i. p. 250.)
+
+[3] Romanes, Galton, and Weismann have made great use of this principle
+in explaining the diminution of disused organs. Weismann has given it
+the name of _Panmixia_,--_all_ individuals being equally free to survive
+and commingle their variations, and not merely selected or favoured
+individuals. See his _Essays on Heredity_, &c., p. 90 (Clarendon Press).
+
+[4] Inclusive in each case of fixed strengthening wire weighing about a
+sixteenth of an ounce or less.
+
+[5] References of course are to _Factors of Organic Evolution_.
+
+[6] P. 13; and _Nineteenth Century_, February, 1888, p. 211.
+
+[7] Tomes's _Dental Surgery_, pp. 273-275. Tomes observes that it is as
+yet uncertain in what way civilization predisposes to caries. But he
+shows that caries is caused by the lime salts in the teeth being
+attacked by _acids_ from decomposing food in crevices, from artificial
+drink such as cyder, from sugar, from medicine, and from vitiated
+secretions of the mouth. It is evident that in civilized races natural
+selection cannot so rigorously insist on sound teeth, sound
+constitutions, and _protective alkaline_ saliva. The reaction of the
+civilized mouth is often acid, especially when the system is disordered
+by dyspepsia or other diseases or forms of ill-health common under
+civilization. The main supply of saliva, which is poured from the cheeks
+opposite the upper molars, is often acid when in small quantities. But
+the submaxillary and sub-lingual saliva poured out at the foot of the
+lower incisors and held in the front part of the jaw as in a spoon,
+"differs from parotid saliva in being more alkaline" (Foster's _Text
+Book of Physiology_, p. 238; Tomes, pp. 284, 685). One observer says
+that the reaction near the lower incisors is "never acid." Hence (I
+conclude) the remarkable immunity of the lower incisors and canines from
+decay, an immunity which extends backwards in a lessening degree to the
+first and second bicuspids. The close packing of the lower incisors may
+assist by preventing the retention of decaying fragments of food. Sexual
+selection may promote caries by favouring white teeth, which are more
+prone to decay than yellow ones. Acid vitiation of the mucus might
+account both for caries and (possibly) for the strange infertility of
+some inferior races under civilization.
+
+[8] _Origin of Species_, pp. 198-9; _Variation of Animals and Plants
+under Domestication_, vol. ii. p. 328 footnote, also p. 206.
+
+[9] Mr. Spencer weakly argues that an advantageous attribute (such as
+swiftness, keen sight, courage, sagacity, strength, &c.) cannot be
+increased by natural selection unless it is "of greater importance, for
+the time being, than most of the other attributes"; and that natural
+selection cannot develop any one superiority when animals are equally
+preserved by "other superiorities." But as natural selection will
+simultaneously eliminate tendencies to slowness, blindness, deafness,
+stupidity, &c., it _must_ favour and improve many points simultaneously,
+although no one of them may be of greater importance than the rest. Of
+course the more complicated the evolution the slower it will be; but
+time is plentiful, and the amount of elimination is correspondingly
+vast.
+
+[10] I venture to coin this concise term to signify _the direct
+inheritance of the effects of use and disuse in kind_. Having a name for
+a thing is highly convenient; it facilitates clearness and accuracy in
+reasoning, and in this particular inquiry it may save some confusion of
+thought from double or incomplete meanings in the shortened phrases
+which would otherwise have to be employed to indicate this great but
+nameless factor of evolution.
+
+[11] _Origin of Species_, pp. 230-232; Bates's _Naturalist on the
+Amazons_. Darwin is "surprised that no one has hitherto advanced the
+demonstrative case of neuter insects, against the well-known doctrine of
+inherited habit, as advanced by Lamarck." As he justly observes, "it
+proves that with animals, as with plants, any amount of modification may
+be effected by the accumulation of numerous, slight, spontaneous
+variations, which are in any way profitable, without exercise or habit
+having been brought into play. For peculiar habits confined to the
+workers or sterile females, however long they might be followed, could
+not possibly affect the males and fertile females, which alone leave any
+descendants." Some slight modification of these remarks, however, may
+possibly be needed to meet the case of "factitious queens," who
+(probably through eating particles of the royal food) become capable of
+producing a few male eggs.
+
+[12] _Descent of Man_, pp. 573, 572, and footnote.
+
+[13] _Contemporary Review_, December, 1875, p. 92.
+
+[14] See _Origin of Species_, pp. 5-8. "Changed conditions induce an
+almost indefinite amount of fluctuating variability, by which the whole
+organization is rendered in some degree plastic" (_Descent of Man_, p.
+30). It also appears that "the nature of the conditions is of
+subordinate importance in comparison with the nature of the organism in
+determining each particular form of variation;--perhaps of not more
+importance than the nature of the spark, by which a mass of combustible
+matter is ignited, has in determining the nature of the flames" (_Origin
+of Species_, p. 8).
+
+
+
+
+DARWIN'S EXAMPLES.
+
+
+The most formidable cases brought forward by Mr. Spencer are from
+Darwin. I shall endeavour to show, however, that Darwin was probably
+wrong in retaining the older explanation of these facts, and that the
+remains of the Lamarckian theory of use-inheritance need not any longer
+encumber the great explanation which has superseded that fallacious and
+unproven theory and has rendered it totally unnecessary. Meanwhile I
+think it is an excellent sign that Mr. Spencer has to complain that
+"Nowadays most naturalists are more Darwinian than Mr. Darwin
+himself"--inasmuch as they are inclined to say that there is "no proof"
+that the effects of use and disuse are inherited. Other excellent signs
+are the recent issue of a translation of Weismann's important essays on
+this and kindred subjects,[15] the strong support given to his views by
+Wallace in his _Darwinism_, and their adoption by Ray Lankester in his
+article on Zoology in the latest edition of the _Encyclopaedia
+Britannica_. So sound and cautious an investigator as Francis Galton had
+also in 1875 concluded that "acquired modifications are barely, if at
+all, _inherited_, in the correct sense of that word."
+
+Darwin's belief in the inheritance of acquired characters was more or
+less hereditary in the family. His grandfather, Erasmus Darwin,
+anticipated Lamarck's views in his _Zoonomia_, which Darwin at one time
+"greatly admired." His father was "convinced" of the "inherited evil
+effects of alcohol," and to this extent at least he strongly impressed
+the belief in the inheritance of acquired characters upon his
+children's minds.[16] Darwin must also have been imbued with Lamarckian
+ideas from other sources, although Dr. Grant's enthusiastic advocacy
+entirely failed to convert him to a belief in evolution.[17]
+"Nevertheless," he says, "it is probable that the hearing rather early
+in life such views maintained and praised may have favoured my upholding
+them under a different form in my _Origin of Species_"--a remark which
+refers to Lamarck's views on the general doctrine of evolution, but
+might also prove equally true if applied to Darwin's partial retention
+of the Lamarckian explanation of that evolution. Professor Huxley has
+pointed out that in Darwin's earlier sketch of his theory of evolution
+(1844) he attached more weight to the inheritance of acquired habits
+than he does in his _Origin of Species_ published fifteen years
+later.[18] He appears to have acquired the belief in early life without
+first questioning and rigorously testing it as he would have done had it
+originated with himself. In later life it appeared to assist his theory
+of evolution in minor points, and in particular it appeared absolutely
+indispensable to him as the _only_ explanation of the diminution of
+disused parts in cases where, as in domestic animals, economy of growth
+seemed to be practically powerless. He failed to adequately notice the
+effect of panmixia, or the withdrawal of selection, in causing or
+allowing degeneracy and dwindling under disuse; and he hardly attached
+sufficient importance to the fact that rudimentary organs and other
+supposed effects of use or disuse are quite as marked features in
+neuter insects which cannot transmit the effects of use and disuse as
+they are in the higher animals.
+
+
+REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS.
+
+Darwin himself has pointed out that the rudimentary wings of island
+beetles, at first thought to be due to disuse, are mainly brought about
+by natural selection--the best-winged beetles being most liable to be
+blown out to sea. But he says that in birds of the oceanic islands "not
+persecuted by any enemies, the reduction of their wings has probably
+been caused by disuse." This explanation may be as fallacious as it is
+acknowledged to have been in the case of the island beetles. According
+to Darwin's own views, natural selection _must_ at least have played an
+important part in reducing the wings; for he holds that "natural
+selection is continually trying to economize every part of the
+organization." He says: "If under changed conditions of life a
+structure, before useful, becomes less useful, its diminution will be
+favoured, for it will profit the individual not to have its nutriment
+wasted in building up an useless structure.... Thus, as I believe,
+natural selection will tend in the long run to reduce any part of the
+organization, as soon as it becomes, through changed habits,
+superfluous."[19] If, as Darwin powerfully urges (and he here ignores
+his usual explanation), ostriches' wings are insufficient for flight in
+consequence of the economy enforced by natural selection,[20] why may
+not the reduced wings of the dodo, or the penguin, or the apteryx, or of
+the Cursores generally, be wholly attributed to natural selection in
+favour of economy of material and adaptation of parts to changed
+conditions? The great principle of economy is continually at work
+shaping organisms, as sculptors shape statues, by removing the
+superfluous parts; and a mere glance at the forms of animals in general
+will show that it is well-nigh as dominant and universal a principle as
+is that of the positive development of useful parts. Other causes,
+moreover besides actual economy, would favour shorter and more
+convenient wings on oceanic islands. In the first place, birds that were
+somewhat weak on the wing would be most likely to settle on an island
+and stay there. Shortened wings would then become advantageous because
+they would restrain fatal migratory tendencies or useless and perilous
+flights in which the birds that flew furthest would be most often
+carried away by storms and adverse winds. Reduced wings would keep the
+birds near the shelter and the food afforded by the island and its
+neighbourhood, and in some cases would become adapted to act as fins or
+flappers for swimming under water in pursuit of fish.
+
+The reduced size of the wings of these island birds is paralleled by the
+remarkable thinness, &c., of the shell of the "gigantic land-tortoise"
+of the Galapagos Islands. The changes seen in the carapace can hardly
+have been brought about by the inherited effects of special disuse. Why
+then should not the reduction of equally useless, more wasteful, and
+perhaps positively dangerous wings be also due to an economy which has
+become advantageous to bird and reptile alike through the absence of the
+mammalian rivals whose places they are evidently being modified to fill?
+The _complete_ loss of the wings in neuter ants and termites can
+scarcely be due to the inherited effects of disuse; and as natural
+selection has abolished these wings in spite of the opposition of
+use-inheritance, it must clearly be fully competent to reduce wings
+without its aid. In considering the rudimentary wings of the apteryx,
+or of the moa, emu, ostrich, &c., we must not forget the frequent or
+occasional occurrence of hard seasons, and times of drought and famine,
+when Nature eliminates redundant, wasteful, and ill-adapted organisms in
+so severe and wholesale a fashion. Where enemies are absent there would
+be unrestrained multiplication, and this would greatly increase the
+severity of the competition for food, and so hasten the elimination of
+disused and useless parts.
+
+
+DROOPING EARS AND DETERIORATED INSTINCTS.
+
+Mr. Galton has pointed out that existing races and existing organs are
+only kept at their present high pitch of organic excellence by the
+stringent and incessant action of natural or artificial selection; and
+the simple relaxation or withdrawal of such selective influences will
+almost necessarily result in a certain amount of deterioration,
+independently even of the principle of economy.[21] I think that this
+cessation of a previous selective process will account for the
+drooping--but _not diminished_--ears of various domesticated animals
+(human preference and increased weight evidently aiding), and also for
+the inferior instincts seen in them and in artificially-fed caterpillars
+of the silk-moth, which now "often commit the strange mistake of
+devouring the base of the leaf on which they are feeding, and
+consequently fall down." Anyhow, I fail to see that anything is proved
+by this latter case, except that natural instinct may be perverted or
+aborted under unnatural conditions and a changed method of selection
+which abolishes the powerful corrective formerly supplied by natural
+selection.
+
+
+WINGS AND LEGS OF DUCKS AND FOWLS.
+
+The reduced wings and enlarged legs of domesticated ducks and fowls are
+attributed by Darwin and Spencer to the inheritance of the effects of
+use and disuse. But the inference by no means follows. Natural selection
+would usually favour these adaptive changes, and they would also have
+been aided by an artificial selection which is often unconscious or
+indirect. Birds with diminished power of flight would be less difficult
+to keep and manage, and in preserving and multiplying such birds man
+would be unconsciously bringing about structural changes which would
+easily be regarded as effects of use and disuse. "About eighteen
+centuries ago Columella and Varro speak of the necessity of keeping
+ducks in netted enclosures like other wild fowl, so that at this period
+there was danger of their flying away."[22] Is it not probable that the
+best fliers would escape most frequently, or would pine most if kept
+confined? On the other hand, birds with lessened powers of flight would
+not be eliminated as under natural conditions, but would be favoured;
+and natural selection, together with artificial selection of the most
+flourishing birds, would thicken and strengthen the legs to meet
+increased demands upon them.
+
+The diminution of the duck's wing is not great even in the birds that
+"never fly," and from this we must deduct the direct effect of disuse on
+the individual during its lifetime. As Weismann suggests, the
+_inherited_ portion of the change could only be ascertained by comparing
+the bones, &c., of wild and tame ducks _similarly reared_. If individual
+disuse diminished the weight of the duck's wing-bones by 9 per cent.
+there would be nothing left to account for.
+
+I suspect that investigation would reveal anomalies inconsistent with
+the theory of use-inheritance. Thus according to Darwin's tables of
+comparative weights and measurements[23] the leg-bones of the Penguin
+duck have slightly diminished in length, although they have increased 39
+per cent. in weight. Relatively to the weight of the skeleton, the
+leg-bones have shortened in the tame breeds of ducks by over 5 per cent.
+(and in two breeds by over 8 per cent.) although they have increased
+more than 28 per cent. in proportional weight.[24] How can increased use
+simultaneously shorten and thicken these bones? If the relative
+shortening is attributed to a heavier skeleton, then the apparently
+reduced weight of the wing-bones is fully accounted for by the same
+circumstance, and disuse has had no inherited effect.
+
+Another strange circumstance is that the wing-bones have diminished _in
+length only_. The shortening is about 6 per cent. more than in the
+shortened legs, and it amounts to 11 per cent. as compared with the
+weight of the skeleton. Such a shortening should represent a reduction
+of 29 per cent. in weight, whereas the actual reduction in the weight of
+the wing-bones relatively to the weight of the skeleton is only 9 per
+cent. even in the breeds that never fly. Independently of shortening,
+the disused wing-bones have actually thickened or increased in weight.
+In the Aylesbury duck the disproportion caused by these conflicting
+changes is so great that the wing-bones are 47 per cent. heavier than
+they should be if their weight had varied proportionally with their
+length.[25] The reduction in weight on which Darwin relies seems to be
+entirely due to the shortening, and this shortening appears to be
+irrelevant to disuse, since the wings of the Call duck are similarly
+shortened in their proportions by 12 per cent., although this bird
+habitually flies to such an extent that Darwin partly attributes the
+greatly increased weight of its wing-bones to increased use under
+domestication.
+
+We find that _all_ the changes are in the direction of shorter and
+thicker bones--a tendency which must be largely dependent upon the
+suspension of the rigorous elimination which keeps the bones of the
+wild duck _long and light_. The used leg-bones and the disused
+wing-bones have alike been shortened and thickened, though in different
+proportions. Natural or artificial selection might easily thicken legs
+without lengthening them, or shorten wings without eliminating strong
+heavy bones, but it can hardly be contended that use-inheritance has
+acted in such conflicting ways. The thickening of the wing-bones has
+actually more than kept pace with any increase of weight in the
+skeleton, in spite of the effect of individual disuse and of the alleged
+cumulative effect of ancestral disuse for hundreds of generations. The
+case of the duck deserves special attention as a crucial one, if only
+from the fact that in this instance, and in this instance only, has
+Darwin given the weights of the skeletons, thus furnishing the means for
+a closer examination of his details than is usually possible.
+
+If we ignore such factors as selection, panmixia, correlation, and the
+effects of use and disuse during lifetime, and still regard the case of
+the domestic duck as a valid proof of the inheritance of the effects of
+use and disuse, we must also accept it as an equally valid proof that
+the effects of use and disuse are _not_ inherited. Nay, we may even have
+to admit that, in two points out of four, the _inherited_ effect of use
+and disuse on successive generations is exactly opposite to the
+immediate effect on the individual.
+
+Among fowls the wing-bones have lost much in weight but little or
+nothing in length--which is the reverse of what has occurred in ducks,
+although disuse is alleged to be the common cause in both cases. Some of
+the fowls which fly least have their wing-bones as long as ever. In the
+case of the Silk and Frizzled fowls--ancient breeds which "cannot fly at
+all"--and in that of the Cochins, which "can hardly fly up to a low
+perch," Darwin observes "how truly the proportions of an organ may be
+inherited although not fully exercised during many generations."[26] In
+four out of twelve breeds the wing-bones had become slightly heavier
+relatively to the leg-bones. Do not these facts tend to show that the
+changes in fowls' wings are due to fluctuating variability and selective
+influences rather than to a general law whereby the effects of disuse
+are cumulatively inherited?
+
+
+PIGEONS' WINGS.
+
+Concerning pigeons' wings Darwin says: "As fancy pigeons are generally
+confined in aviaries of moderate size, and as even when not confined
+they do not search for their own food, they must during many generations
+have used their wings incomparably less than the wild rock-pigeon ...
+but when we turn to the wings we find what at first appears a wholly
+different and unexpected result."[27] This unexpected increase in the
+spread of the wings from tip to tip is due to the feathers, which have
+lengthened in spite of disuse. Excluding the feathers, the wings were
+shorter in seventeen instances, and longer in eight. But as artificial
+selection has lengthened the wings in some instances, why may it not
+have shortened them in others? Wings with shortened bones would fold up
+more neatly than the long wings of the Carrier pigeon for instance, and
+so might unconsciously be favoured by fanciers. The selection of elegant
+birds with longer necks or bodies would cause a relative reduction in
+the wings--as with the Pouter, where the wings have been greatly
+lengthened but not so much as the body.[28] Slender bodies, too, and the
+lessened divergence of the furculum,[29] would slightly diminish the
+spread of the wings, and so would affect the measurements taken. As the
+wing-bones, moreover, are to some extent correlated with the beak and
+the feet, the artificial selection of shortened beaks might tend to
+shorten the wing as well as the feet. Under these circumstances how can
+we be sure of the actual efficacy of use-inheritance? Surely selection
+is as fully competent to effect slight changes in the direction of
+use-inheritance as it undoubtedly is to effect great changes in direct
+opposition to that alleged factor of evolution.
+
+
+SHORTENED BREAST-BONE IN PIGEONS.
+
+The shortening of the sternum in pigeons is attributed to disuse of the
+flight muscles attached to it. The bone is only shortened by a third of
+an inch, but this represents a very remarkable reduction in proportional
+length, which Darwin estimates at from one-seventh to one-eighth, or
+over 13 per cent. This marked reduction, too, quite unlike the slight
+reduction of the wing-bones to which the other ends of the muscles are
+attached, was universal in the eleven specimens measured by Darwin; and
+the bone, though acknowledged to have been modified by artificial
+selection in some breeds, is not so open to observation as wings or
+legs. Even, however, if this relative shortening of the sternum remained
+otherwise inexplicable, it might still be as irrelevant to use and
+disuse as is the fact that "many breeds" of fancy pigeons have lost a
+rib, having only seven where the ancestral rock-pigeon has eight.[30]
+But the excessive reduction in the sternum is far from being
+inexplicable. In the first place Darwin has somewhat over-estimated it.
+Instead of comparing the deficiency of length with the increased length
+which _should_ have been acquired (since the pigeons have increased in
+average size) he compares it with the length of the breast-bone in the
+rock-pigeon.[31] By this method if a pigeon had doubled in dimensions
+while its breast-bone remained unaltered, the reduction would be put
+down as 100 per cent., whereas obviously the true reduction would be
+one-half, or 50 per cent. of what the bone _should be_. Avoiding this
+error and a minor fallacy besides, a sound estimate reduces the supposed
+reduction of 13 or 14 per cent. to one of 11.7 per cent., which is still
+of course a considerable diminution.
+
+Part of this reduction must be due to the direct effect of disuse during
+the lifetime of the individual. Another and perhaps very considerable
+part of the relative change must be attributed to the lengthening of the
+neck or body by artificial selection, or to other modifications of
+shape and proportion effected directly or indirectly by the same
+cause.[32] The reduction is greatest in the Pouter (18-1/2 per cent.)
+and in the Pied Scanderoon (17-1/2 per cent.). In the former the body
+has been greatly elongated by artificial selection and three or four
+additional vertebrae have been acquired in the hinder part of the
+body.[33] In the latter a long neck increases the length of the bird,
+and so causes, or helps to cause, the relative shortening of the
+breast-bone. In the English Carrier--which experiences the effects of
+disuse, as it is too valuable to be flown--the relative reduction of 11
+per cent. is apparently more than accounted for by the "elongated
+neck." The Dragon also has a long neck. In the Pouter, although the
+breast-bone has been shortened by 18-1/2 per cent. relatively to the
+length of the body, it has _lengthened_ by 20 per cent. relatively to
+the _bulk_ of the body.[34] Darwin forgot to ask whether allowance must
+not be made for a frequent, or perhaps general, elongation of the neck
+and the hinder part of the body, and the relative shortening or the
+throwing forward of the central portion containing the ribs (frequently
+one less in number) and the sternum. The whole body of the pigeon is so
+much under the control of artificial selection, that every precaution
+must be taken to guard against such possible sources of error.[35]
+
+Under domestication there would be a suspension of the previous
+elimination of reduced breast-bones by natural selection (Weismann's
+panmixia), and a diminution of the parts concerned in flying might even
+be favoured, as lessened powers of _continuous_ flight would prevent
+pigeons from straying too far, and would fit them for domestication or
+confinement. Such causes might reduce some of the less observed parts
+affected by flying, while still leaving the wing of full size for
+occasional flight, or to suit the requirements of the pigeon-fanciers. A
+change might thus be commenced like that seen in the rudimentary keel of
+the sternum in the owl-parrot of New Zealand, which has lost the power
+of flight although still retaining fairly-developed wings.
+
+
+SHORTENED FEET IN PIGEONS.
+
+Darwin thinks it highly probable that the short feet of most breeds of
+pigeons are due to lessened use, though he owns that the effects of
+correlation with the shortened beak are more plainly shown than the
+effects of disuse.[36] But why need the inherited effects of disuse be
+called in to explain an average reduction of some 5 per cent., when
+Darwin's measurements show that in the breeds where long beaks are
+favoured the principle of correlation between these parts has lengthened
+the foot by 13 per cent. in spite of disuse?
+
+
+SHORTENED LEGS OF RABBITS.
+
+In the case of the domestic rabbit Darwin notices that the bones of the
+legs have (relatively) become shorter by an inch and a half. But as the
+leg-bones have _not_ diminished in relative weight,[37] they must
+clearly have grown _thicker_ or denser. If disuse has shortened them, as
+Darwin supposes, why has it also thickened them? The ears and the tail
+have been lengthened in spite of disuse. Why then may not the ungainly
+hind-legs have been shortened by human preference independently of the
+inherited effects of disuse? By relying on apparently favourable
+instances and neglecting the others it would be easy to arrive at all
+manner of unsound conclusions. We might thus become convinced that
+vessels tend to sail northwards, or that a pendulum oscillates more
+often in one direction than in the other. It must not be forgotten that
+it would be easy to cite an enormous number of cases which are in direct
+conflict with the supposed law of use-inheritance.
+
+
+BLIND CAVE-ANIMALS.
+
+Weak or defective eyesight is by no means rare as a spontaneous
+variation in animals, "the great French veterinary Huzard going so far
+as to say that a blind race [of horses] could soon be formed." Natural
+selection evolves blind races whenever eyes are useless or
+disadvantageous, as with parasites. This may apparently be done
+independently of the effects of disuse, for certain neuter ants have
+eyes which are reduced to a more or less rudimentary condition, and
+neuter termites are blind as well as wingless. In one species of ant
+(_Eciton vastator_) the sockets have disappeared as well as the eyes. In
+deep caves not only would natural selection cease to maintain good
+eyesight but it would persistently favour blindness--or the entire
+removal of the eye when greatly exposed, as in the cave-crab--and as Dr.
+Ray Lankester has indicated,[38] there would have been a previous
+selection of animals which through spontaneous weakness, sensitiveness,
+or other affection of the eye found refuge and preservation in the cave,
+and a subsequent selection of the descendants whose fitness for relative
+darkness led them deeper into the cave or prevented them from straying
+back to the light with its various dangers and severer competition.
+Panmixia, however, as Weismann has shown, would probably be the most
+important factor in causing blindness.
+
+
+INHERITED HABITS.
+
+Darwin says: "A horse is trained to certain paces, and the colt inherits
+similar consensual movements."[39] But selection of the constitutional
+tendency to these paces, and imitation of the mother by the colt, may
+have been the real causes. The evidence, to be satisfactory, should show
+that such influences were excluded. Men acquire proficiency in swimming,
+waltzing, walking, smoking, languages, handicrafts, religious beliefs,
+&c., but the children only appear to inherit the innate abilities or
+constitutional proclivities of their parents. Even the songs of birds,
+including their call-notes, are no more inherited than is language by
+man (_Descent of Man_, p. 86). They are learned from the parent.
+Nestlings which acquire the song of a distinct species, "teach and
+transmit their new song to their offspring." If use-inheritance has not
+fixed the song of birds, why should we suppose that in a single
+generation it has transmitted a newly-taught method of walking or
+trotting?
+
+It is alleged that dogs inherit the intelligence acquired by association
+with man, and that retrievers inherit the effects of their
+training.[40] But selection and imitation are so potent that the
+additional hypothesis of use-inheritance seems perfectly superfluous.
+Where intelligence is not highly valued and carefully promoted by
+selection, the intelligence derivable from association with man does
+_not_ appear to be inherited. Lap-dogs, for instance, are often
+remarkably stupid.
+
+Darwin also instances the inheritance of dexterity in seal-catching as a
+case of use-inheritance.[41] But this is amply explained by the ordinary
+law of heredity. All that is needed is that the son shall inherit the
+suitable faculties which the father inherited before him.
+
+
+TAMENESS OF RABBITS.
+
+Darwin holds that in some cases selection alone has modified the
+instincts and dispositions of domesticated animals, but that in most
+cases selection and the inheritance of acquired habits have concurred in
+effecting the change. "On the other hand," he says, "habit alone in some
+cases has sufficed; hardly any animal is more difficult to tame than the
+young of the wild rabbit; scarcely any animal is tamer than the young of
+the tame rabbit; but I can hardly suppose that domestic rabbits have
+often been selected for tameness alone; so that we must attribute at
+least the greater part of the inherited change from extreme wildness to
+extreme tameness to habit and long-continued close confinement."[42]
+
+But there are strong, and to me irresistible, arguments to the contrary.
+I think that the following considerations will show that the greater
+part, if not the whole, of the change must be attributed to selection
+rather than to the direct inheritance of acquired habit.
+
+(1) For a period which may cover thousands of generations, there has
+been an entire cessation of the natural selection which maintains the
+wildness (or excessive fear, caution, activity, &c.) so indispensably
+essential for preserving defenceless wild rabbits of all ages from the
+many enemies that prey upon them.
+
+(2) During this same extensive period of time man has usually killed off
+the wildest and bred from the tamest and most manageable. To some extent
+he has done this consciously. "It is very conducive to successful
+breeding to keep only such as are quiet and tractable," says an
+authority on rabbits,[43] and he enjoins the selection of the
+handsomest and _best-tempered_ does to serve as breeders. To a still
+greater extent man has favoured tameness unconsciously and indirectly.
+He has systematically selected the largest and most prolific animals,
+and has thus doubled the size and the fertility of the domestic rabbit.
+In consciously selecting the largest and most flourishing individuals
+and the best and most prolific mothers, he _must_ have unconsciously
+selected those rabbits whose relative _tameness_ or placidity of
+disposition rendered it possible for them to flourish and to produce and
+rear large and thriving families, instead of fretting and pining as the
+wilder captives would do. When we consider how exceedingly delicate and
+easily disturbed yet all-important a function is that of maternity in
+the continually breeding rabbit, we see that the tamest and the least
+terrified would be the most successful mothers, and so would continually
+be selected, although man cared nothing for the tameness in itself. The
+tamest mothers would also be less liable to neglect or devour their
+offspring, as rabbits commonly do when their young are handled too soon,
+or even when merely frightened by mice, &c., or disturbed by changed
+surroundings.
+
+(3) We must remember the extraordinary fecundity of the rabbit and the
+excessive amount of elimination that consequently takes place either
+naturally or artificially. Where nature preserved only the wildest, man
+has preserved the tamest. If there is any truth in the Darwinian theory,
+this thorough and long-continued reversal of the selective process
+_must_ have had a powerful effect. Why should it not be amply sufficient
+to account for the tameness and mental degeneracy of the rabbit without
+the aid of a factor which can readily be shown to be far weaker in its
+normal action than either natural or artificial selection? Why may not
+the tameness of the rabbit be transferred to the group of cases in
+which Darwin holds that "habit has done nothing," and selection has done
+all?
+
+(4) If use-inheritance has tamed the rabbit, why are the bucks still so
+mischievous and unruly? Why is the Angora breed the only one in which
+the males show no desire to destroy the young? Why, too, should
+use-inheritance be so much more powerful in the rabbit than with other
+animals which are far more easily tamed in the first instance? Wild
+young rabbits when domesticated "remain unconquerably wild," and,
+although they may be kept alive, they pine and "rarely come to any
+good." Yet the animal which _acquires_ least tameness--or apparently,
+indeed, none at all--inherits most! It appears, in fact, to inherit that
+which it cannot acquire--a circumstance which indicates the selection of
+spontaneous variations rather than the inheritance of changed habits.
+Such variations occasionally occur in animals in a marked degree. Of a
+litter of wolf-cubs, all brought up in the same way, "one became tame
+and gentle like a dog, while the others preserved their natural
+savagery." Is it not probable that permanent domestication was rendered
+possible by the inevitable selection of spontaneous variations in this
+direction? The _excessive_ tameness, too, of the young rabbit, while
+easily explicable as a result of unconscious selection, is not easily
+explained as a result of acquired habit. No particular care is taken to
+tame or teach or domesticate rabbits. They are bred for food, or for
+profit or appearance, and they are left to themselves most of their
+time. As Sir J. Sebright notices with some surprise, the domestic rabbit
+"is not often visited, and seldom handled, and yet it is always tame."
+
+
+MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION.
+
+Innumerable modifications in accordance with altered use or disuse, such
+as the enlarged udders of cows and goats, and the diminished lungs and
+livers in highly bred animals that take little exercise, can be readily
+and fully explained as depending on selection. As the fittest for the
+natural or artificial requirements will be favoured, natural or
+artificial selection may easily enlarge organs that are increasingly
+used and economize in those that are less needed. I therefore see no
+necessity whatever for calling in the aid of use-inheritance as Darwin
+does, to account for enlarged udders, or diminished lungs, or the thick
+arms and thin legs of canoe Indians, or the enlarged chests of
+mountaineers, or the diminished eyes of moles, or the lost feet of
+certain beetles, or the reduced wings of logger-headed ducks, or the
+prehensile tails of monkeys, or the displaced eyes of soles, or the
+altered number of teeth in plaice, or the increased fertility of
+domesticated animals, or the shortened legs and snouts of pigs, or the
+shortened intestines of tame rabbits, or the lengthened intestines of
+domestic cats, &c.[44] Changed habits and the requisite change of
+structure will usually be favoured by natural selection; for habit, as
+Darwin says, "almost implies that some benefit great or small is thus
+derived."
+
+
+SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE.
+
+Here we perceive a difficulty which will equally trouble those who
+affirm use-inheritance and those who deny. Broadly speaking, the
+adaptive effects ascribed to use-inheritance coincide with the effects
+of natural selection. The individual adaptability (as shown in the
+thickening of skin, fur, muscle, &c., under the stimulus of friction,
+cold, use, &c.) is identical in kind and direction with the racial
+adaptability under natural selection. Consequently the alleged
+inheritance of the advantageous effects of use and disuse cannot readily
+be distinguished from the similarly beneficial effects of natural
+selection. The indisputable fact that natural selection imitates or
+simulates the beneficial effects ascribed to use-inheritance may be the
+chief source and explanation of a belief which may prove to be
+thoroughly fallacious. A similar simulation of course occurs under
+domestication, where natural selection is partly replaced by artificial
+selection of the best adapted and therefore most flourishing animals,
+while in disused parts panmixia or the comparative cessation of
+selection will aid or replace "economy of growth" in causing
+diminution.[45]
+
+
+INFERIORITY OF SENSES IN EUROPEANS.
+
+"The inferiority of Europeans, in comparison with savages, in eyesight
+and in the other senses," is attributed to "the accumulated and
+transmitted effect of lessened use during many generations."[46] But why
+may we not attribute it to the slackened and diverted action of the
+natural selection which keeps the senses so keen in some savage races?
+
+
+SHORT-SIGHT IN WATCHMAKERS AND ENGRAVERS.
+
+Darwin notices that watchmakers and engravers are liable to be
+short-sighted, and that short-sight and long-sight certainly tend to be
+inherited.[47] But we must be careful not to beg the question at issue
+by assuming that the frequent heredity of short sight necessarily covers
+the heredity of artificially-produced short-sight. Elsewhere, however,
+Darwin states more decisively that "there is ground for believing that
+it may often originate in causes acting on the individual affected, and
+may thence-forward become transmissible."[48] This impression may arise
+(1) from the facts of ordinary heredity--the ancestral liability being
+excited in father and son by similar artificial habits, such as reading,
+and viewing objects closely as among watchmakers and engravers--or by
+constitutional deterioration from indoor life, &c., acting upon a
+constitutional liability of the eye to the "something like inflammation
+of the coats, under which they yield" and so cause shortness of sight
+by altering the spherical shape of the eye-ball. (2) Panmixia, or the
+suspension of natural selection, together with altered habits, will
+account for an increase of short-sight among the population generally.
+(3) Long-sighted people could not work at watchmaking and engraving so
+comfortably and advantageously as at other occupations, and hence would
+be less likely to take to such callings.
+
+
+LARGER HANDS OF LABOURERS' INFANTS.[49]
+
+These are best explained as the result of natural selection and of the
+diminution of the hand by sexual selection in the gentry. If the larger
+hands of labourers' infants are really due to the inherited effects of
+ancestral use, why does the development occur so early in life, instead
+of only at a corresponding period, as is the rule? During the first few
+years of its life, at least, the labourer's infant does no more work
+than the gentleman's child. Why are not the effects of this disuse
+inherited by the labourer's infant? If the enlargement of the infant's
+hand illustrates the transference of a character gained later in life,
+it is evident that the transference must take place in spite of the
+inherited effects of disuse.
+
+
+THICKENED SOLE IN INFANTS.
+
+Darwin also attributes the thickened sole in infants, "long before
+birth," to "the inherited effects of pressure during a long series of
+generations."[50] But disuse should make the infant's sole _thin_, and
+it is this thinness that should be inherited. If we suppose the
+inheritance of the thickened soles of later life to be transferred to an
+earlier period, we have the anomaly of the inherited effects of disuse
+at that earlier period being overpowered by the untimely inheritance of
+the effects of use at another. On the other hand, it is clear that
+natural selection would favour thickened soles for walking on, and might
+also promote an early development which would ensure their being ready
+in good time for actual use; for variations in the direction of delay
+would be cut off, while variations in the other direction would be
+preserved. Anyhow, the mere transference of a character to an earlier
+period is no proof of use-inheritance. The real question is whether the
+thickened sole was gained by natural selection or by the inherited
+effects of pressure, and the mere transference or hastened appearance of
+the thickening does not in any degree solve this question. It merely
+excludes the effect of disuse during lifetime, and thus presents a
+fallacious appearance of being decisive. The thickened sole of the
+unborn infant, however, like the lanugo or hairy covering, is probably a
+result of the direct inheritance of ancestral stages of evolution, of
+which the embryo presents a condensed epitome. While the relative
+thinness of the infant's sole might be pointed to as the effect of
+_disuse_ during a long series of generations, its thickness is rather an
+illustration of atavism still resisting the effects of long-continued
+disuse. There is nothing to show that the inheritable portion of the
+full original thickness was not gained by natural selection rather than
+by the directly inherited effect of use; and the latter, being
+cumulative and indiscriminative in its action, would apparently have
+made the sole very much thicker and harder than it is. If natural
+selection were not supreme in such cases, how could we account for the
+effects of pressure resulting in hard hoofs in some cases and only soft
+pads in others?
+
+
+A SOURCE OF MENTAL CONFUSION.
+
+Of course in a certain sense this thickening of the sole has resulted
+from use. In one sense or other, most--or perhaps all--of the results of
+natural selection are inherited effects of use or disuse. Natural
+selection preserves that which is of use and which is used, while it
+eliminates that which is useless and is not used. The most confident
+assertions of the effects of use and disuse in modifying the heritable
+type, appear to rest on this indefeasible basis. Darwin's statements
+concerning the effects of use and disuse in evolution can frequently be
+read in two senses. They often command assent as undeniable truisms as
+they stand, but are of course written in another and more debatable
+sense. Thus in the case of the shortened wings and thickened legs of the
+domestic duck, I believe equally with Darwin and Spencer that "no one
+will dispute that they have resulted from the lessened use of the wings
+and the increased use of the legs." "Use" is at bottom the determining
+circumstance in evolution generally. The trunk of the elephant, the fin
+of the fish, the wing of the bird, the cunning hand of man and his
+complicated brain--and, in short, all organs and faculties
+whatsoever--can only have been moulded and developed by use--by
+usefulness and by using--but not necessarily by use-inheritance, not
+necessarily by directly inherited effects of use or disuse of parts in
+the individual. So, too, reduced or rudimentary organs are due to
+disuse, but it by no means follows that the diminution is caused by any
+direct tendency to the inheritance of the effects of disuse in the
+individual. The effects of natural selection are commonly expressible as
+effects of use and disuse, just as adaptation in nature is expressible
+in the language of teleology. But use-inheritance is no more proven by
+one of these necessary coincidences than special design is by the
+other. The inevitable simulation of use-inheritance may be entirely
+deceptive.
+
+Darwin thinks that "there can be no doubt that use in our domestic
+animals has strengthened and enlarged certain parts, and disuse
+diminished them; and that such modifications are inherited." Undoubtedly
+"such" or _similar_ modifications have often been inherited, but how can
+Darwin possibly tell that they are not due to the simulation of
+use-inheritance by natural or artificial selection acting upon general
+variability? Of the inevitability of selection and of its generally
+adaptive tendencies "there can be no doubt," and panmixia would tend to
+reduce disused parts; so that there _must always_ remain grave doubts of
+the alleged inheritance of the similar effects of use and disuse, unless
+we can accomplish the extremely difficult feat of excluding both natural
+and artificial selection as causes of enlargement, and panmixia and
+selection as causes of dwindling.
+
+
+WEAKNESS OF USE-INHERITANCE.
+
+Use-inheritance is normally so weak that it appears to be quite helpless
+when opposed to any other factor of evolution. Natural selection evolves
+and maintains the instincts of ants and termites in spite of
+use-inheritance to a more wonderful degree than it evolves the instincts
+of almost any other animal with the fullest help of use-inheritance. It
+develops seldom-used horns or natural armour just as readily as
+constantly-used hoofs or teeth. Sexual selection evolves elaborate
+structures like the peacock's tail in spite of disuse and natural
+selection combined. Artificial selection appears to enlarge or diminish
+used parts or disused parts with equal facility. The assistance of
+use-inheritance seems to be as unnecessary as its opposition is
+ineffective.
+
+The alleged inheritance of the effects of use and disuse in our domestic
+animals must be very slow and slight.[51] Darwin tells us that "there
+is no good evidence that this ever follows in the course of a single
+generation." "Several generations must be subjected to changed habits
+for any appreciable result."[52] What does this mean? One of two things.
+Either the tendency is very weak, or it is non-existent. If it is so
+weak that we cannot detect its alleged effects till several generations
+have elapsed, during which time the more powerful agency of selection
+has been at work, how are we to distinguish the effects of the minor
+factor from that of the major? Are we to conclude that use-inheritance
+_plus_ selection will modify races, just as Voltaire firmly held that
+incantations, together with sufficient arsenic, would destroy flocks of
+sheep? Is it not a significant fact that the alleged instances of
+use-inheritance so often prove to be self-conflicting in their details?
+
+For satisfactory proof of the prevalence of a law of use-inheritance we
+require normal instances where selection is clearly inadequate to
+produce the change, or where it is scarcely allowed time or opportunity
+to act, as in the immediate offspring of the modified individual. Of the
+first kind of cases there seems to be a plentiful lack. Of the latter
+kind, according to Darwin, there appears to be none--a circumstance
+which contrasts strangely and suspiciously with the many decisive cases
+in which variation from unknown causes has been inherited most
+strikingly in the immediate offspring. It must be expected, indeed, that
+among these innumerable cases some will accidentally mimic the alleged
+effects of use-inheritance.
+
+If Darwin had felt certain that the effects of habit or use tended in
+any marked degree to be conveyed directly and cumulatively to succeeding
+generations, he could hardly have given us such cautious, half-hearted
+encouragement of good habits as the following:--"It is not improbable
+that after long practice virtuous tendencies may be inherited." "Habits,
+moreover followed during many generations probably tend to be
+inherited."[53] This is probable, independently of use-inheritance. The
+"many generations" specified or implied, will allow time for the play of
+selective as well as of cumulatively-educative influences. There must
+apparently be a constitutional or inheritable predisposition or fitness
+for the habits spoken of, which otherwise would scarcely be continued
+for many generations, except by the favourably-varying branches of a
+family: which again is selection rather than use-inheritance.
+
+Where is the necessity for even the remains of the Lamarckian doctrine
+of inherited habit? Seeing how powerful the general principle of
+selection has shown itself in cases where use-inheritance could have
+given no aid or must even have offered its most strenuous opposition,
+why should it not equally be able to develop used organs or repress
+disused organs or faculties without the assistance of a relatively weak
+ally? Selection evolved the remarkable protective coverings of the
+armadillo, turtle, crocodile, porcupine, hedgehog, &c.; it formed alike
+the rose and its thorn, the nut and its shell; it developed the
+peacock's tail and the deer's antlers, the protective mimicry of various
+insects and butterflies, and the wonderful instincts of the white ants;
+it gave the serpent its deadly poison and the violet its grateful odour;
+it painted the gorgeous plumage of the Impeyan pheasant and the
+beautiful colours and decorations of countless birds and insects and
+flowers. These, and a thousand other achievements, it has evidently
+accomplished without the help of use-inheritance. Why should it be
+thought incapable of reducing a pigeon's wing or enlarging a duck's
+leg? Why should it be credited with the help of an officious ally in
+effecting comparatively slight changes, when great and striking
+modifications are effected without any such aid?
+
+
+FOOTNOTES:
+
+[15] Weismann's _Essays on Heredity_, &c. Clarendon Press, 1889.
+
+[16] _Life and Letters_, i. p. 16. Darwin's reverence for his father
+"was boundless and most touching. He would have wished to judge
+everything else in the world dispassionately, but anything his father
+had said was received with almost implicit faith; ... he hoped none of
+his sons would ever believe anything because he said it, unless they
+were themselves convinced of its truth--a feeling in striking contrast
+with his own manner of faith" (_Life and Letters_, i. pp. 10, 11).
+
+[17] _Ibid._, i. p. 38.
+
+[18] _Life and Letters_, ii. p. 14.
+
+[19] _Origin of Species_, pp. 117, 118.
+
+[20] _Ibid._, p. 180.
+
+[21] _Contemporary Review_, December, 1875, pp. 89, 93.
+
+[22] _Variation of Animals and Plants under Domestication_, i. 292.
+
+[23] _Variation of Animals and Plants under Domestication_, i. 299-301.
+
+[24] To keep pace with this lateral increase in weight, the leg-bones
+should have lengthened considerably so that their total deficiency in
+proportional length is 17 per cent.,--a changed proportion which being
+_linear_ is more excessive than the increase of weight by 28 per cent.
+So marked is the effect of the combined thickening and shortening that
+in the Aylesbury breed--which is the most typically representative
+one--the leg-bones have become 70 per cent. heavier than they should be
+if their thickness had continued to be proportional to their length.
+
+[25] This excessive thickening under disuse appears to be due partly to
+a positive lateral enlargement or increase of proportional weight of
+about 7-1/2 per cent., and partly to a shortening of about 15 per cent.
+Carefully calculated, the reduction of the weight of the wing-bones in
+this breed is only 8.3 per cent. relatively to the whole skeleton, or
+only 5 per cent. relatively to the skeleton _minus_ legs and wings. The
+latter method is the more correct, since the excessive weight of the
+leg-bones increases the weight of the skeleton more than the diminished
+weight of the wing-bones reduces it.
+
+[26] _Variation of Animals and Plants under Domestication_, i. 284.
+
+[27] _Variation of Animals and Plants under Domestication_, i. 184, 185.
+
+[28] _Ibid._, i. 144, 145.
+
+[29] _Ibid._, i. 185.
+
+[30] _Variation of Animals and Plants under Domestication_, i. 175.
+
+[31] _Variation of Animals and Plants under Domestication_, i. 184. I
+suspect that Darwin was in poor health when he wrote this page. He nods
+at least four times in it. Twice he speaks of "twelve" breeds where he
+obviously should have said eleven.
+
+[32] If a prominent breast is admired and selected by fanciers, the
+sternum might shorten in assuming a more forward and vertical position.
+If the shortening of the sternum is entirely due to disuse, it seems
+strange that Darwin has not noticed any similar shortening in the
+sternum of the duck. But selection has not tended to make the duck
+elegant, or "pigeon-breasted"; it has enlarged the abdominal sack
+instead, besides allowing the addition of an extra rib in various cases.
+
+[33] _Variation of Animals and Plants under Domestication_, 144, 175.
+
+[34] _Variation of Animals and Plants under Domestication_, i. 179.
+
+[35] In the six largest breeds the shortening of the sternum is nearly
+twice as great as in the three smaller breeds which remain nearest the
+rock-pigeon in size. We can hardly suppose that use-inheritance
+especially affects the eight breeds that have varied most in size. If we
+exclude these, there is only a total shortening of 7 per cent. to be
+accounted for.
+
+[36] _Variation of Animals and Plants under Domestication_, i. 183, 186.
+
+[37] _Variation of Animals and Plants under Domestication_, i. 130, 135;
+ii. 288.
+
+[38] _Encyclopaedia Britannica_, article "Zoology."
+
+[39] _Variation of Animals and Plants under Domestication_, ii. 367.
+
+[40] _Variation of Animals and Plants under Domestication_, ii. 367. Why
+then does the cheetah inherit ancestral habits so inadequately that it
+is useless for the chase unless it has first learned to hunt for itself
+before being captured? (ii. 133).
+
+[41] _Descent of Man_, p. 33.
+
+[42] _Origin of Species_, pp. 210, 211.
+
+[43] E. S. Delamer on _Pigeons and Rabbits_, pp. 132, 103. For other
+points referred to, see pages 133, 102, 100, 95, 131.
+
+[44] _Origin of Species_, pp. 188, 110; _Descent of Man_, pp. 32-35;
+_Variation of Animals and Plants under Domestication_, ii. 289, 293. Use
+or disuse during lifetime of course co-operates, and in some cases, as
+in that of the canoe Indians, may be the principal or even perhaps the
+_sole_ cause of the change.
+
+[45] For the importance of panmixia as invalidating Darwin's strongest
+evidence for use-inheritance--namely, that drawn from the effects of
+disuse in highly-fed domestic animals where there is supposed to be no
+economy of growth--see Professor Romanes on Panmixia, _Nature_, April 3,
+1890.
+
+[46] _Descent of Man_, p. 33.
+
+[47] _Descent of Man_, p. 33.
+
+[48] _Variation of Animals and Plants under Domestication_, i., 453.
+
+[49] _Descent of Man_, p. 33.
+
+[50] _Descent of Man_, p. 33.
+
+[51] Wallace shows that the changes in our domestic animals, if spread
+over the thousands of years since the animals were first tamed, must be
+extremely insignificant in each generation, and he concludes that such
+infinitesimal effects of use and disuse would be swallowed up by the far
+greater effects of variation and selection (_Darwinism_, p. 436).
+Professor Romanes has replied to him in the _Contemporary Review_
+(August 1889), showing that this is no disproof of the existence of the
+minor factor, inasmuch as slight changes in each generation need not
+necessarily be matters of life and death to the individual, although
+their cumulative development by use-inheritance might eventually become
+of much service. But selection would favour spontaneous variations of a
+similarly serviceable character. The slightest tendency to eliminate the
+extreme variations in either direction would proportionally modify the
+average in a breed. Use-inheritance appears to be so relatively weak a
+factor that probably neither proof nor disproof of its existence can
+ever be given, owing to the practical impossibility of disentangling its
+effects (if any) from the effects of admittedly far more powerful
+factors which often act in unsuspected ways. Thus wild ducklings, which
+can easily be reared by themselves, invariably "die off" if reared with
+tame ones (_Variation_, &c., i. 292, ii. 219). They cannot get their
+fair share in the competition for food, and are completely eliminated.
+Professor Romanes fully acknowledges that there is the "gravest possible
+doubt" as to the transmission of the effects of disuse (Letter on
+Panmixia, _Nature_, March 13, 1890).
+
+[52] _Variation of Animals and Plants under Domestication_, ii. 287-289.
+
+[53] _Descent of Man_, pp. 612, 131.
+
+
+
+
+INHERITED INJURIES.
+
+
+INHERITED MUTILATIONS.
+
+The almost universal _non-inheritance_ of mutilations seems to me a far
+more valid argument _against_ a general law of modification-inheritance
+than the few doubtful or abnormal cases of such inheritance can furnish
+in its favour. No inherited effect has been produced by the docking of
+horses' tails for many generations, or by a well-known mutilation which
+has been practised by the Hebrew race from time immemorial. As lost or
+mutilated parts are reproduced in offspring independently of the
+existence of those parts in the parent, there is the less reason to
+suppose that the particular condition of parental parts transmits
+itself, or tends to transmit itself, to the offspring. So unsatisfactory
+is the argument derivable from inherited mutilations that Mr. Spencer
+does not mention them at all, and Darwin has to attribute them to a
+special cause which is independent of any general theory of
+use-inheritance.[54]
+
+Darwin's most striking case--and to my mind the only case of any
+importance--is that of Brown-Sequard's epileptic guinea-pigs, which
+inherited the mutilated condition of parents who had gnawed off their
+own gangrenous toes when anaesthetic through the sciatic nerve having
+been divided.[55] Darwin also mentions a cow that lost a horn by
+accident, followed by suppuration, and subsequently produced three
+calves which had on the same side of the head, instead of a horn, a bony
+lump attached merely to the skin. Such cases may seem to prove that
+mutilation _associated with morbid action_ is occasionally inherited or
+repeated with a promptitude and thoroughness that contrast most
+strikingly with the imperceptible nature of the immediate inheritance of
+the effects of use and disuse; but they by no means prove that
+mutilation in general is inheritable, and they are absolutely no proof
+whatever of a _normal_ and non-pathological tendency to the inheritance
+of acquired characters. Those who accept Darwin's special explanation
+of the supposed inheritance of mutilations, ought to notice that his
+explanation applies equally well under a theory which is strongly
+adverse to use-inheritance--namely, Galton's idea of the sterilization
+and complete "using up" of otherwise reproductive matter in the growth
+and maintenance of the personal structure.
+
+Darwin's explanation of inherited mutilations--which, as he notes, occur
+"especially or perhaps exclusively" when the injury has been followed by
+disease[56]--is that all the representative gemmules which would develop
+or repair or reproduce the injured part are attracted to the diseased
+surface during the reparative process and are there destroyed by the
+morbid action.[57] Hence they cannot reproduce the part in offspring.
+This explanation by no means implies that mutilation would _usually_
+affect the offspring. On the contrary, in all ordinary cases of
+mutilation the purely atavistic elements or gemmules would be set free
+from any modifying influence of the non-existent or mutilated part. The
+gemmules--as in Galton's theory of heredity and with neuter
+insects--might be perfectly independent of pangenesis and the normal
+inheritance of acquired characters. Such self-multiplying gemmules
+without pangenesis would enable us to understand both the excessive
+weakness or non-existence of normal use-inheritance, and the excessive
+strength and abruptness of the effect of their partial destruction under
+special pathological conditions.
+
+The series of epileptic phenomena that can be excited by tickling a
+certain part of the cheek and neck of the adult guinea-pig during the
+growth and rejoining of the ends of the severed nerve, are said to be
+repeated with striking accuracy of detail in the young who inherit
+mutilated toes; but as epilepsy is often due to some _one_ exciting
+cause or morbid condition, the single transmission of a highly morbid
+condition of the system might easily reproduce the whole chain of
+consequences and might also have caused the loss of toes.
+
+The particulars of the guinea-pig cases are very inadequately
+recorded,[58] but the results are so anomalous[59] that Brown-Sequard's
+own conclusion is that the epilepsy and the inherited injuries are
+_not_ directly transmitted, but that "what is transmitted is the morbid
+state of the nervous system." He thinks that the missing toes may
+"possibly" be exceptions to this conclusion, "but the other facts only
+imply the transmission of a morbid state of the sympathetic or sciatic
+nerve or of a part of the medulla oblongata." Until we can tell what is
+transmitted, we are not in a position to determine whether there is any
+true inheritance or only an exaggerated simulation of it under peculiar
+circumstances. When the actual observers believe that the mutilations
+and epilepsy are not the cause of their own repetition, and when these
+observers guard themselves by such phrases as, "if any conclusion can at
+present be drawn from those facts," we who have only incomplete reports
+to guide us may well be excused if we preserve an even more pronounced
+attitude of caution and reserve.[60] The morbid state of the system may
+be wholly due to general injury of the germs rather than to specific
+inheritance.
+
+Weismann suggests that the morbid condition of the nervous system may be
+due to some infection such as might arise from microbes, which find a
+home in the mutilated and disordered nervous system in the parent, and
+subsequently transmit themselves to the offspring through the
+reproductive elements, as the infections of various diseases appear to
+do--the muscardine silkworm disease in particular being known to be
+conveyed to offspring in this manner.
+
+But whether we can discover the true explanation or not, inherited
+mutilations can hardly be accounted for as the result of a general
+tendency to inherit acquired modifications. How could a factor which
+seems to be totally inoperative in cases of ordinary mutilation, and
+only infinitesimally operative in transmitting the normal effects of use
+and disuse, suddenly become so powerful as to completely overthrow
+atavism, and its own tendency to transmit the non-mutilated type of one
+of the parents and of the non-mutilated type presented by the injured
+parent in earlier life? Does not so striking and abrupt an
+intensification of its usually insignificant power demand an explanation
+widely different from that which might account for the extremely slow
+and slight inheritance of the normal effects of use and disuse? Surely
+it would be better to suspend one's judgment as to the true explanation
+of highly exceptional and purely pathological cases rather than resort
+to an hypothesis that creates more difficulties than it solves.
+
+
+THE MOTMOT'S TAIL.
+
+The narrowing of the long central tail feathers of the motmot is
+attributed to the inherited effects of habitual mutilation (_Descent of
+Man_, pp. 384, 603). But in the specimens at South Kensington[61] the
+narrowness extends upwards much beyond the habitually denuded part, and
+the broadened end is the broadest part of the whole feather. If the
+inherited effect of an inch or two of denudation extends from three to
+six inches upwards, why has it not also extended two inches downwards so
+as to narrow the broadened end? The narrowness seems to be a mainly
+relative or negative effect produced by the broadening out of a long
+tapering feather at its end under the influence of sexual selection.
+Several other birds have similarly narrowed or spoon-shaped feathers and
+do not bite them. Is it not more feasible to suppose that this
+attractive peculiarity first suggested its artificial intensification,
+than to suppose that the bird began nibbling without any definite cause?
+Sexual selection would then encourage the habit. Anyhow, it is as
+impossible to show that the mutilation preceded the narrowing as it is
+to show that tonsure preceded baldness.
+
+
+OTHER INHERITED INJURIES MENTIONED BY DARWIN.
+
+Darwin quotes some cases from Dr. Prosper Lucas's "long" but weak and
+unsatisfactory "list of inherited injuries."[62] But Lucas was somewhat
+credulous. One of his cases is that many girls were born in London
+without mammae through the injurious effect of certain corsets on the
+mothers. He also gives a long account of a Jew who could read through
+the thick covers of a book, and whose son inherited this "hyperaesthesia"
+of the sense of sight in a still more remarkable degree (i. 113-119).
+Evidently Lucas's cases cannot be accepted without some amount of
+reserve.
+
+The cases of the three calves which inherited the one-horned condition
+of the cow, the two sons who inherited a father's crooked finger, and
+the two sons who were microphthalmic on the same side as their father
+had lost an eye, may be due to mere coincidence; or an inherited
+constitutional tendency or liability might lead to somewhat similar
+results in parent and offspring[63]--just as the tendency to certain
+fatal diseases or to suicide may produce similar results in father and
+son, although the artificially-produced hanging or apoplexy obviously
+cannot be directly transmitted. That more than one of the offspring was
+affected does not render the chances against coincidence "almost
+infinitely great," as Darwin mistakenly supposes. It "frequently occurs"
+that a man's sons or daughters may _all_ exhibit either a latent or a
+newly-developed congenital peculiarity previously unknown;[64] and the
+coincidence may merely be that one of the parents accidentally suffered
+a similar kind of injury--a kind of coincidence which must of course
+occasionally occur, and which may have been partly caused by a latent
+tendency. The chances against coincidence are indeed great, but the
+cases appear to be correspondingly rare.
+
+Darwin acknowledges that many supposed instances of inherited mutilation
+may be due to coincidence; and there is apparently no more reason for
+attributing inherited scars, &c., to any special form of heredity than
+to the effect of the mother's imagination on the unborn babe--a popular
+but fallacious belief in corroboration of which far more alleged
+instances could be collected than of the inheritance of injuries.
+
+As an instance of the coincidences that occur, I may mention that a
+friend of mine has a daughter who was born with a small hole in one ear,
+just as if it were already pierced for the earring which she has since
+worn in it. I suppose, however, that no one will venture to claim this
+as an instance of the inheritance of a mutilation practised by female
+ancestors, especially as such holes are not altogether unknown or
+inexplicable, though very rarely occurring low down in the lobe of the
+ear.[65]
+
+Many cases are known of the inheritance of mutilations or malformations
+arising congenitally from some abrupt variation in the reproductive
+elements. In such cases as the one-eared rabbits, the two-legged pigs,
+the three-legged dogs, the one-horned stags, hornless bulls, earless
+rabbits, lop-eared rabbits, tailless dogs, &c., if the father or the
+mother or the embryo had suffered from some accident or disease which
+might plausibly have been assigned as the cause of the original
+malformation, these transmitted defects would readily be cited as
+instances of the inheritance of an accidentally-produced modification.
+
+The inheritance of exostoses on horses' legs may be the inheritance of a
+constitutional tendency rather than of the effect of the parents' hard
+travelling. Horses congenitally liable to such formations would transmit
+the liability,[66] and this might readily be mistaken for inheritance of
+the results of the liability. An apparent increase in this liability
+might arise from greater attention being now paid to it, or from
+increased use of harder roads; or a real increase might be due to
+panmixia and some obscure forms of correlation.
+
+
+QUASI-INHERITANCE.
+
+Of course artificially-caused ill-health or weakness in parents will
+tend in a general way to injure the offspring. But deterioration thus
+caused is only a form of quasi-inheritance, as I should prefer to call
+it. Semi-starvation in a new-born babe is _not_ truly inherited from its
+half-starved mother, but is the direct result of insufficient
+nourishment. The general welfare of germs--as of parasites--is
+necessarily bound up with that of the organism which feeds and shelters
+them, but this is not heredity, and is quite irrelevant to the question
+whether particular modifications are transmitted or not.
+
+Another form of quasi-inheritance is seen in the communication of
+certain infections to offspring. Not being transmitted by the action of
+the organism so much as in defiance of it, such diseases are not truly
+hereditary, though for convenience' sake they are usually so described.
+
+A perversion or prevention of true inheritance is also seen in the
+action of alcohol, or excessive overwork, or any other cause which by
+originating morbid conditions in individuals may also injure the
+reproductive elements.
+
+These forms of quasi-inheritance are, of course, highly important so far
+as the improvement of the race is concerned. So, too, is the fact that
+improved or deteriorated habits and thoughts are transmitted by personal
+teaching and influence and are cumulative in their effect. But all this
+must not be confounded with the inheritance of acquired characters.
+Cases of quasi-inheritance may perhaps be most readily distinguished
+from cases of true inheritance by the time test. When a modification
+acquired in adult life is promptly communicated to the child in early
+life or from birth, it may rightly be suspected that the inheritance,
+like that of money or title, is not truly congenital, but is extraneous
+or even anti-congenital in its nature. Judged by such a standard, the
+inherited injuries in Brown-Sequard's guinea-pigs are only exceptional
+cases of quasi-inheritance, and are not necessarily indicative of any
+general rule affecting true inheritance.
+
+
+FOOTNOTES:
+
+[54] A very able anatomist of my acquaintance denies the inheritance of
+mutilations and injuries, although he strongly believes in the
+inheritance of the effects of use and disuse.
+
+[55] _Variation of Animals and Plants under Domestication_, i. 467-469.
+Lost toes were only seen by Dr. Dupuy in three young out of two hundred.
+Obersteiner found that most of the offspring of his epileptic
+guinea-pigs were injuriously affected, being weakly, small, paralysed in
+one or more limbs, and so forth. Only two were epileptic, and both were
+weakly and died early (Weismann's _Essays_, p. 311). A morbid condition
+of the spinal cord might affect the hind limbs especially (as in
+paraplegia) and might occasionally cause loss of toes in the embryo by
+preventing development or by ulceration. Brown-Sequard does not say that
+the defective feet were on the same side as in the parents (_Lancet_,
+Jan., 1875, pp. 7, 8).
+
+[56] _Variation of Animals and Plants under Domestication_, ii. 57.
+
+[57] _Ibid._, ii. 392. Perhaps it might be better to suppose that the
+_best_ gemmules were sacrificed in repairing the injured _nerve_, and
+hence only inferior substitutes were left to take their place, and could
+only imperfectly reproduce the injured part of the nervous system in
+offspring.
+
+[58] Hence perhaps Mr. Spencer's error in representing the epileptic
+liability as permanent and as coming on _after_ healing (_Factors of
+Organic Evolution_, p. 27).
+
+[59] It is not claimed that the imperfect foot was on the same side of
+the body as in the parent, and where parents had lost _all_ the toes of
+a foot, or the whole foot, the few offspring affected usually had lost
+only two toes out of the three, or only a part of one or two or three
+toes. Sometimes the offspring had toes missing on _both_ hind feet,
+although the parent was only affected in _one_. _One_ diseased ear and
+eye in the parent was "generally" or "always" succeeded by _two_ equally
+affected ears and eyes in the offspring (cf. _Pop. Science Monthly_, New
+York, xi. 334). The important law of inheritance at corresponding
+periods was also set aside. Gangrene or inflammation commenced in both
+ears and both eyes soon after birth (pointing possibly to infection of
+some kind); the epileptic period commenced "perhaps two months or more
+after birth," while the loss of toes had occurred before birth. In no
+case, as Weismann points out, is the original mutilation of the nervous
+system ever transmitted. Even where an extirpated ganglion was never
+regenerated in the parent, the offspring always regained the part in an
+apparently perfect condition. On the whole the conflicting results ought
+to be as puzzling to those who may attribute them to a universal
+tendency to inherit the exact condition of parents as they are to those
+who, like myself, are sceptical as to the existence of such a law or
+tendency.
+
+[60] The various results need to be fully and impartially recorded, and
+they should also be well tested and confirmed in proportion as they
+appear improbable and contrary to general experience. Professor Romanes
+has been carrying out the necessary experiments for some time past.
+
+[61] Natural History Museum, central hall, third recess on the left.
+
+[62] _Traite de l'Heredite_, ii. 489; _Variation of Animals and Plants
+under Domestication_, i. 469. If injuries are inherited, why has the
+repeated rupture of the hymen produced no inherited effect?
+
+[63] Compare the three cases of crooked fingers given in _Variation of
+Animals and Plants under Domestication_, ii. 55, 240.
+
+[64] _Ibid._, i. 460. Thus, where two brothers married two sisters all
+the seven children were perfect albinos, although none of the parents or
+their relatives were albinos. In another case the nine children of two
+sound parents were all born blind (ii. 322).
+
+[65] See pp. 179-182, _Evolution and Disease_, by J. Bland Sutton, to
+whom and to our mutual friend Dr. D. Thurston I am indebted for
+information on various points.
+
+[66] _Variation of Animals and Plants under Domestication_, ii. 290; i.
+454.
+
+
+
+
+MISCELLANEOUS CONSIDERATIONS.
+
+
+TRUE RELATION OF PARENTS AND OFFSPRING.
+
+It is difficult to entirely free ourselves from the flattering and
+almost universal idea that parents are true originators or creators of
+copies of themselves. But the main truth, if not the whole truth, is
+that they are merely the transmitters of types of which they and their
+offspring are alike more or less similarly moulded resultants. A parent
+is a trustee. He transmits, not himself and his own modifications, but
+the stock, the type, the representative elements, of which he is a
+product and a custodian in one. It seems probable that he has no more
+definite or "particulate" influence over the reproductive elements
+within him than a mother over the embryo or a vessel over its cargo.
+Parent and offspring are like successive copies of books printed from
+the same "type." A battered letter in the "type" will display its
+effects in both earlier and later copies alike, but a purely extraneous
+or acquired flaw in the first copy is not necessarily repeated in
+subsequent copies. Unlike printer's type, however, the material source
+of heredity is of a fluctuating nature, consisting of competing elements
+derived from two parents and from innumerable ancestors.
+
+Galton compares parent and child to successive pendants on the same
+chain. Weismann likens them to successive offshoots thrown up by a long
+underground root or sucker. Such comparisons indicate the improbability
+of acquired modifications being transmitted to offspring.
+
+That parts are developed in offspring independently of those parts in
+parents is clear. Mutilated parents transmit parts which they do not
+possess. The offspring of young parents cannot inherit the later stages
+of life from parents who have not passed through them. Cases of remote
+reversion or atavism show that ancestral peculiarities can transmit
+themselves in a latent or undeveloped condition for hundreds or
+thousands of generations. Many obvious facts compelled Darwin to suppose
+that vast numbers of the reproductive gemmules in an individual are not
+thrown off by his own cells, but are the self-multiplying progeny of
+ancestral gemmules. Galton restricts the production of gemmules by the
+personal structure to a few exceptional cases, and would evidently like
+to dispense with pangenesis altogether, if he could only be sure that
+acquired characters are never inherited. Weismann entirely rejects
+pangenesis and the inheritance of acquired characters. This enables him
+to explain heredity by his theory of the "Continuity of the
+Germ-plasm."[67] Parent and offspring are alike successive products or
+offshoots of this persistent germ-substance, which obviously would not
+be correspondingly affected by modifications of parts in parents, and so
+would render the transmission of acquired characters impossible.
+
+
+INVERSE INHERITANCE.
+
+Mr. Galton contends that the reproductive elements become sterile when
+used in forming and maintaining the individual, and that only a small
+proportion of them are so used.[68] He holds that the next generation
+will be formed entirely, or almost entirely, from the residue of
+undeveloped germs, which, not having been employed in the structure and
+work of the individual, have been free to multiply and form the
+reproductive elements whence future individuals are derived. Hence the
+singular inferiority not infrequently displayed by the children of men
+of extraordinary genius, especially where the ancestry has been only of
+a mediocre ability. The valuable germs have been used up in the
+individual, and rendered sterile in the structure of his person. Hence,
+too, the "strong tendency to deterioration in the transmission of every
+exceptionally gifted race." Mr. Galton's hypothesis "explains the fact
+of certain diseases skipping one or more generations," and it "agrees
+singularly well with many classes of fact;" and it is strongly opposed
+to the theory of use-inheritance. The elements which are used die almost
+universally without germ progeny: the germs which are _not_ used are the
+great source of posterity. Hence, when the germs or gemmules which
+achieve development are either better or worse than the residue, the
+qualities transmitted to offspring will be of an inverse character. If
+brain-work attracts, develops _and sterilizes_ the best gemmules, the
+ultimate effect of education on the intellect of posterity may differ
+from its immediate effect.
+
+
+EARLY ORIGIN OF THE OVA.
+
+As the ova are formed at as early a period as the rest of the maternal
+structure, Galton notices that it seems improbable that they would be
+correspondingly affected by subsequent modifications of parental
+structure. Of course it is not certain that this is a valid argument. We
+know that the paternal half of the reproductive elements does not enter
+the ovum till a comparatively late stage in its history, and it is quite
+possible that maternal elements or gemmules may also enter the ovum from
+without. If reproductive elements were confined to one special part or
+organ, we should be unable to explain the reproduction of lost limbs in
+salamanders, and the persistent effect of intercrossing on subsequent
+issue by the same mother, and the propagation of plants from shoots, or
+of the begonia from minute fragments of leaves, or the development of
+small pieces of water-worms into complete animals.
+
+
+MARKED EFFECTS OF USE AND DISUSE ON THE INDIVIDUAL.
+
+These are, to some extent, an argument against the cumulative
+inheritance of such effects. When a nerve atrophies from disuse, or a
+duct shrivels, or bone is absorbed, or a muscle becomes small or flabby,
+it proves, so far, that the average effect of use through enormous ages
+is _not_ transmitted. When the fibula of a dog's leg thickens by 400 per
+cent. to a size "equal to or greater than" that of the removed tibia
+which previously did the work,[69] it shows that in spite of disuse for
+countless generations, the "almost filiform" bone has retained a
+potentiality of development which is fully equal to that possessed by
+the larger one which has been constantly used. When, after being reared
+on the ailanthus, the caterpillars of the _Bombyx hesperus_ die of
+hunger rather than return to their natural food, the inherited effect of
+ancestral habit does not seem to be particularly strong. Neither is
+there any strongly-inherited effect of long-continued ancestral wildness
+in many animals which are easily tamed.
+
+
+WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE?
+
+If use-inheritance is really one of the factors of evolution, it is
+certainly a subordinate one, and an utterly helpless one, whenever it
+comes into conflict with the great ruling principle of Selection. Would
+this dominant cause of evolution have favoured a tendency to
+use-inheritance if such had appeared, or would it have discouraged and
+destroyed it? We have already seen that use-inheritance is unnecessary,
+since natural selection will be far more effective in bringing about
+advantageous modifications; and if it can be shown that use-inheritance
+would often be an evil, it then becomes probable that on the whole
+natural selection would more strongly discourage and eliminate it as a
+hostile factor than it might occasionally favour such a tendency as a
+totally unnecessary aid.
+
+
+USE-INHERITANCE AN EVIL.
+
+Use-inheritance would crudely and indiscriminately proportion parts to
+actual work done--or rather to the varying _nourishment and growth_
+resulting from a multiplicity of causes--and this in its various details
+would often conflict most seriously with the real necessities of the
+case, such as occasional passive strength, or appropriate shape,
+lightness and general adaptation. If its accumulated effects were not
+corrected by natural or sexual selection, horns and antlers would
+disappear in favour of enlarged hoofs. The elephant's tusks would become
+smaller than its teeth. Men would have callosities for sitting on, like
+certain monkeys, and huge corns or hoofs for walking on. Bones would
+often be modified disastrously. Thus 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. Some organs (like the heart, which is
+always at work) would become inconveniently or unnecessarily large.
+Other absolutely indispensable organs, which are comparatively passive
+or are very seldom used, would dwindle until their weakness caused the
+ruin of the individual or the extinction of the species. In eliminating
+various evil results of use-inheritance, natural selection would be
+eliminating use-inheritance itself. The displacement of Lamarck's theory
+by Darwin's shows that the effects of use-inheritance often differ from
+those required by natural selection; and it is clear that the latter
+factor must at least have reduced use-inheritance to the very minor
+position of comparative feebleness and harmlessness assigned to it by
+Darwin.
+
+Use-inheritance would be ruinous through causing unequal variation in
+co-operative parts--of which Mr. Spencer may accept his own instances of
+the jaws and teeth, and the cave-crab's lost eyes and persistent
+eye-stalks, as typical examples. That the variation would be unequal
+seems almost self-evident from the varying rapidity and extent of the
+effects of use and disuse on different tissues and on different parts of
+the general structure. The optic nerve may atrophy in a few months from
+disuse consequent on the loss of the eye. Some of the bones of the
+rudimentary hind legs of the whale are still in existence after disuse
+for an enormous period. Evidently use-inheritance could not equally
+modify the turtle and its shell, or the brain and its skull; and in
+minor matters there would be the same incongruity of effect. Thus, if
+the molar teeth lengthened from extra use the incisors could not meet.
+Unequal and indiscriminate variation would throw the machinery of the
+organism out of gear in innumerable ways.
+
+Use-inheritance would perpetuate various evils. We are taught, for
+instance, that it perpetuates short-sight, inferior senses, epilepsy,
+insanity, nervous disorders, and so forth. It would apparently transmit
+the evil effects of over-exertion, disuse, hardship, exposure, disease
+and accident, as well as the defects of age or immaturity.
+
+Would it not be better on the whole if each individual took a fresh
+start as far as possible on the advantageous typical lines laid down by
+natural selection? Through the long stages of evolution from primaeval
+protoplasm upwards, such species as were least affected by
+use-inheritance would be most free to develop necessary but seldom-used
+organs, protective coverings such as shells or skulls, and natural
+weapons, defences, ornaments, special adaptations, and so forth; and
+this would be an advantage--for survival would obviously depend on the
+_importance_ of a structure or faculty in deciding the struggle for
+existence and reproduction, and not on the total amount of its using or
+nourishment. If natural selection had on the whole favoured this
+officious ally and frequent enemy, surely we should find better evidence
+of its existence.
+
+Without laying undue stress upon the evil effects of use-inheritance, a
+careful examination of them in detail may at least serve to
+counter-balance the optimistic _a priori_ arguments for belief in that
+plausible but unproven factor of evolution.
+
+The benefits derivable from use-inheritance are largely illusory. The
+effects of _use_, indeed, are generally beneficial up to a certain
+point; for natural selection has sanctioned or evolved organs which
+possess the property or potentiality of developing to the right extent
+under the stimulus of use or nourishment. But use-_inheritance_ would
+cumulatively alter this individual adaptability, and would tend to fix
+the size of organs by the average amount of ancestral use or disuse
+rather than by the actual requirements of the individual. Of course
+under changed conditions involving increased or lessened use of parts it
+might become advantageous; but even here it may prove a decided
+hindrance to adaptive evolution in some respects as well as an
+unnecessary aid in others. Thus in the case of animals becoming heavier,
+or walking more, it would _lengthen_ the legs although natural selection
+might require them to be shortened. In the Aylesbury duck and the Call
+duck, if use-inheritance has increased the dimensions of the bones and
+tendons of the leg, natural selection has had to counteract this
+increase so far as length is concerned, and to effect 8 per cent. of
+shortening besides. If use-inheritance thickens bones without
+proportionally lengthening them, it would hinder rather than help the
+evolution of such structures as the long light wings of birds, or the
+long legs and neck of the giraffe or crane.
+
+
+VARIED EFFECTS OF USE AND DISUSE.
+
+The changes which we somewhat roughly and empirically group together as
+the effects of "use and disuse" are of widely diverse character. Thus
+bone, as the physiological fact, thickens under _alternations_ of
+pressure (and the consequent increased flow of nourishment), but
+atrophies under a steadily continued pressure; so that if the use of a
+bone involved continuous pressure, the effect of such use would be a
+partial or total absorption of that bone. Darwin shows that bone
+lengthens as well as thickens from carrying a greater weight, while
+tension (as seen in sailors' arms, which are used in pulling) appears to
+have an equally marked effect in shortening bones (_Descent of Man_, p.
+32). Thus different kinds of use may produce opposite results. The
+cumulative inheritance of such effects would often be mischievous. The
+limbs of the sloth and the prehensile tail of the spider monkey would
+continually grow shorter, while the legs of the evolving elephant or
+rhinoceros might lengthen to an undesirable extent. Such cumulative
+tendencies of use-inheritance, if they exist, are obviously well kept
+under by natural selection.
+
+Although the ultimate effect of use is generally growth or enlargement
+through increased flow of blood, the first effect usually is a loss of
+substance, and a consequent diminution of size and strength. When the
+loss exceeds the growth, use will diminish or deteriorate the part used,
+while disuse would enlarge or perfect it. Teeth, claws, nails, skin,
+hair, hoofs, feathers, &c., may thus be worn away faster than they can
+renew themselves. But this wearing away usually stimulates the repairing
+process, and so increases the rate of growth; that is, it will increase
+the size produced, if not the size retained. Which effect of use does
+use-inheritance transmit in such cases--the increased rate of growth, or
+the dilapidation of the worn-out parts? We can hardly suppose that both
+these effects of use will be inherited. Would shaving destroy the beard
+in time or strengthen it? Will the continued shearing of sheep increase
+or lessen the growth of wool? What will be the ultimate effect of
+plucking geese's quills, and of the eider duck's abstraction of the down
+from her breast? If the mutilated parts grow stronger or more
+abundantly, why were the motmot's feathers alleged to be narrowed by the
+inherited effects of ancestral nibbling?
+
+The "use" or "work" or "function" of muscles, nerves, bones, teeth,
+skin, tendon, glands, ducts, eyes, blood corpuscles, cilia, and the
+other constituents of the organism, is as widely different as the
+various parts are from each other, and the effects of their use or
+disuse are equally varied and complicated.
+
+
+USE-INHERITANCE IMPLIES PANGENESIS.
+
+How could the transmission of these varied effects to offspring be
+accounted for? Is it possible to believe, with Mr. Spencer, that the
+effects of use and disuse on the parts of the personal structure are
+simultaneously registered in corresponding impressions on the seminal
+germs? Must we not feel, with Darwin apparently,[70] that the _only_
+intelligible explanation of use-inheritance is the hypothesis of
+Pangenesis, according to which each modified cell, or physiological
+unit, throws off similarly-modified gemmules or parts of itself, which
+ultimately reproduce the change in offspring? If we reject pangenesis,
+it becomes difficult to see how use-inheritance can be possible.
+
+
+PANGENESIS IMPROBABLE.
+
+The more important and best-known phenomena of heredity do not require
+any such hypothesis, and leading facts (such as atavism, transmission of
+lost parts, and the general non-transmission of acquired characters) are
+so adverse to it that Darwin has to concede that many of the
+reproductive gemmules are atavistic, and that by continuous
+self-multiplication they may preserve a practical "continuity of
+germ-substance," as Weismann would term it. The idea that the
+relationship of offspring to parent is one of direct descent is, as
+Galton tells us, "wholly untenable"; and the only reason he admits some
+supplementary traces of pangenesis into his "Theory of Heredity,"[71] is
+that he may thus account for the more or less questionable cases of the
+transmission of acquired characters. But there appears to be no
+necessity even for this concession. We ought therefore to dispense with
+the useless and gratuitous hypothesis that cells multiply by throwing
+off minute self-multiplying gemmules, as well as by the well-known
+method of self-division. If pangenesis occurs, the transmission of
+acquired characters ought to be a prominent fact. The size, strength,
+health and other good or evil qualities of the cells could hardly fail
+to exercise a marked and corresponding effect upon the size and quality
+of the reproductive gemmules thrown off by those cells. The direct
+evidence tends to show that these free gemmules do not exist.
+Transfusion of blood has failed to affect inheritance in the slightest
+degree. Pangenesis, with its attraction of gemmules from all parts of
+the body into the germ-cells, and the free circulation of gemmules in
+the offspring till they hit upon or are attracted by the particular cell
+or cells, with which alone they can readily unite, seems a less feasible
+theory and less in conformity with the whole of the facts than an
+hypothesis of germ-continuity which supposes that the development of the
+germ-plasm and of the successive self-dividing cells of the body
+proceeds from within. Darwin's keen analogy of the fertilization of
+plants by pollen renders development from without conceivable, but as
+there are no insects to convey gemmules to their destination, each kind
+of gemmule would have to be exceedingly numerous and easily attracted
+from amongst an inconceivable number of other gemmules. Arguments
+against pangenesis can also be drawn from the case of neuter insects--a
+fact which seems to have escaped Darwin's notice, although he had seen
+how strongly that case was opposed to the doctrine which is the
+essential basis of the theory of pangenesis.
+
+
+SPENCER'S EXPLANATION OF USE-INHERITANCE.
+
+Mr. Spencer's explanation of the inheritance of the effects of use and
+disuse (p. 36) is that "while generating a modified _consensus_ of
+functions and of structures, the activities are at the same time
+impressing this modified _consensus_ on the sperm-cells and germ-cells
+whence future individuals are to be produced"--a proposition which reads
+more like metaphysics than science. Difficult to understand or believe
+in ordinary instances, such _consensus_-inheritance seems impossible in
+cases like that of the hive-bee. Can we suppose that the _consensus_ of
+the activities of the working bee impresses itself on the sperm-cells
+of the drones and on the germ-cells of the carefully secluded queen?
+Buechner thinks so, for he says: "Although the queens and drones do not
+now work, yet the capacities inherited from earlier times still remain
+to them, especially to the former, and are kept alive and fresh by the
+impressions constantly made upon them during life, and they are thus in
+a position to transmit them to posterity." Surely it is better to
+abandon a cherished theory than to be compelled to defend it by
+explanations which are as inconsistent as they are inadequate. New
+capacities are developed as well as old ones kept fresh. The massacre or
+expulsion of the drones would have to impress itself on the germ-cells
+of an onlooking queen, and the imprisonment of the queen on the
+sperm-cells of the drones--and in such a way, moreover, as to be
+afterwards developed into action in the neuters only. And
+use-inheritance all the while is being thoroughly overpowered by
+impression-inheritance--by the full transmission of that which is merely
+seen in others! If such a law prevails, one may feel cold because an
+ancestor thought of the frosty Caucasus. None of this absurdity would
+arise if it were clearly seen that a parent is only a trustee--that
+transmission and development are perfectly distinct--that parental
+modifications are irrelevant to those transmitted to offspring.
+
+
+FOOTNOTES:
+
+[67] _Essays on Heredity_, p. 104. Weismann's theory is clear, simple
+and convenient, but incomplete; for, unlike Darwin's theory of
+pangenesis, it scarcely attempts any real explanation of the extremely
+complex potentialities possessed by the reproductive elements. Perhaps
+we might retain Darwin's self-multiplying gemmules without supposing
+them to be thrown off by the cells, which will no longer be credited
+with _two_ modes of multiplication. These minute germs or gemmules may
+have been evolved by natural selection playing upon the sample germs
+that achieve development; and they may exist either separately, or
+(preferably but perhaps not invariably) in aggregates to form Weismann's
+germ-plasm.
+
+[68] _Contemporary Review_, Dec., 1875, p. 88.
+
+[69] _Variation of Animals and Plants under Domestication_, ii. 286.
+
+[70] _Variation of Animals and Plants under Domestication_, ii. 388,
+398, 367; _Life and Letters_, iii. 44.
+
+[71] _Contemporary Review_, Dec., 1875, pp. 94, 95.
+
+
+
+
+CONCLUSIONS.
+
+
+USE-INHERITANCE DISCREDITED AS UNNECESSARY, UNPROVEN, AND IMPROBABLE.
+
+General experience teaches that acquired characters are not usually
+inherited; and investigation shows that the apparent exceptions to this
+great rule are probably fallacious. Even the alleged instances of
+use-inheritance culled by such great and judicious selectors as Darwin
+and Spencer break down upon examination; for they can be better
+explained without use-inheritance than with it. On the other hand, the
+adverse facts and considerations are almost strong enough to prove the
+actual non-existence of such a law or tendency. There is no need to
+undertake the apparently impossible task of demonstrating an absolute
+negative. It will be enough to ask that the Lamarckian factor of
+use-inheritance shall be removed from the category of accredited factors
+of evolution to that of unnecessary and improbable hypotheses. The main
+explanation or source of the fallacy may be found in the fact that
+natural selection frequently imitates some of the more obvious effects
+of use and disuse.
+
+
+MODERN RELIANCE ON USE-INHERITANCE MISPLACED.
+
+Modern philanthropy--so far at least as it ever studies ultimate
+results--constantly relies on this ill-founded belief as its
+justification for ignoring the warnings of those who point out the
+ultimately disastrous results of a systematic defiance or reversal of
+the great law of natural selection. This reliance finds strong support
+in Mr. Spencer's latest teachings, for he holds that the inheritance of
+the effects of use and disuse takes place universally, and that it is
+now "the chief factor" in the evolution of civilized man (pp. 35, 74,
+iv)--natural selection being quite inadequate for the work of
+progressive modification. Practically he abandons the hope of evolution
+by natural selection, and substitutes the ideal of a nation being
+"modified _en masse_ by transmission of the effects" of its institutions
+and habits. Use-inheritance will "mould its members far more rapidly and
+comprehensively" than can be effected by the survival of the fittest
+alone.
+
+But could we rely upon the aid of use-inheritance if it really were a
+universal law and not a mere simulation of one? Let us consider some of
+the features of this alleged factor of evolution, seeing that it is
+henceforth to be our principal means of securing the improvement of our
+species and our continued adaptation to the changing conditions of a
+progressive civilization.
+
+It is curiously uncertain and irregular in its action. It diminishes or
+abolishes some structures (such as jaws or eyes) without correspondingly
+diminishing or abolishing other equally disused and closely related
+parts (such as teeth, or eye-stalks). It thickens ducks' leg-bones while
+allowing them to shorten. It shortens the disused wing-bones of ducks
+and the leg-bones of rabbits while allowing them to thicken; and yet in
+other cases it greatly reduces the thickness of bones without shortening
+them. It transmits tameness most powerfully in an animal which usually
+cannot acquire it. It aids in webbing the feet of water-dogs, but fails
+to web the feet of the water-hen or to remove the web in the feet of
+upland geese.[72] It allows the disused fibula to retain a potentiality
+of development fully equal to that possessed by the long-used tibia. It
+lengthens legs because they are used in supporting the body, and
+shortens arms because they are used in pulling. Whether it enlarges
+brain if used in one way and diminishes it if used in another, we cannot
+tell; but it must obviously deaden nervous sensibilities in some cases
+and intensify them in others. It enlarges hands long before they are
+used, and thickens soles long before the time for walking on them. At
+the same time, as if by an oversight, it so delays its transmission of
+the habit of walking on these thickened soles, that the gradual and
+tedious acquisition of the non-transmitted habit costs the infant much
+time and trouble and often some pain and danger. Yet where aided by
+natural selection, as with chickens and foals, it transmits the habit in
+wonderful perfection and at a remarkably early date. It transmits new
+paces in horses in a single generation, but fails to perpetuate the
+songs of birds. It modifies offspring like parents, and yet allows the
+formation of two reproductive types in plants, and of two or more types
+widely different from the parents in some of the higher insects. It is
+said to be indispensable for the co-ordinated development of man and the
+giraffe and the elk, but appears to be unnecessary for the evolution and
+the maintenance of wonderful structures and habits and instincts in a
+thousand species of ants and bees and termites. It is the only possible
+means of complex evolution and adaptation of co-operative parts, and yet
+in Mr. Spencer's most representative case it renders such important
+parts as teeth and jaws unsuited for each other, and is said to ruin the
+teeth by the consequent overcrowding and decay. It survives amidst a
+general "lack of recognised evidence," and only seems to act usefully
+and healthily and regularly in quarters where it can least easily be
+distinguished from other more powerful and demonstrable factors of
+evolution. So little does it care to display its powers where they would
+be easily verifiable as well as useful that practical breeders ignore
+it. So slight is its independent power that it seems to allow natural
+selection or sexual selection or artificial selection to modify
+organisms in sheer defiance of its utmost opposition, just as readily as
+they modify organisms in other directions with its utmost help. If it
+partially perpetuates and extends the pecked-out indentations in the
+motmot's tail feathers, it on the other hand fails to transmit the
+slightest trace of mutilation in an almost infinite number of ordinary
+cases, and even where the mutilation is repeated for a hundred
+generations; and it apparently repairs rather than transmits the
+ordinary and oft-repeated losses caused by plucking hair, down and
+feathers, and the wear and tear of claws, teeth, hoofs and skin.
+
+It is often mischievous as well as anomalous in its action. Under
+civilization with its division of labour, the various functions of mind
+and body are very unequally exercised. There is overwork or misuse of
+one part and disuse and neglect of others, leading to the partial
+breakdown or degeneration of various organs and to general deterioration
+of health through disturbed balance of the constitution. The brain, or
+rather particular parts of it, are often over-stimulated, while the body
+is neglected. In many ways education and civilization foster nervousness
+and weakness, and undermine the rude natural health and spirits of the
+human animal. Alcohol, tobacco, tea, coffee, extra brain work, late
+hours, dissipation, overwork, indoor life, division of labour,
+preservation of the weak, and many other causes, all help to injure the
+modern constitution; so that the prospect of cumulative intensification
+of these evils by the additional influence of use-inheritance is not an
+encouraging one. It is true that modern progress and prosperity are
+improving the people in various respects by their direct action; but if
+use-inheritance has any share in effecting this improvement it must also
+transmit increased wants and more luxurious habits, together with such
+evils as have already been referred to. As depicted by its defenders,
+use-inheritance transmits evils far more powerfully and promptly than
+benefits. It transmits insanity and shattered nerves rather than the
+healthy brain which preceded the breakdown. It perpetuates, and
+cumulatively intensifies, a deterioration in the senses of civilized
+men, but it fails to perpetuate the rank vigour of various plants when
+too well nourished, or the flourishing condition of various animals when
+too fat or when tamed. It already transmits the short-sight caused by so
+modern an art as watchmaking, but so fails to transmit the
+long-practised art of seeing (as it does of walking and talking) that
+vision is worse than useless to a man until he gradually acquires the
+necessary but non-transmitted associations of sensation and idea by his
+own experience. In a well-known case, a blind man on gaining his sight
+by an operation said that "all objects seemed to touch his eyes, as what
+he felt did his skin"--so little had the universal experience of
+countless ages impressed itself on his faculties. Under normal healthy
+conditions use-inheritance is so slow in its action that "several
+generations" must elapse before it produces any appreciable effect, and
+then that effect is only precisely what selection might be expected to
+bring about without its aid. Strong for evil and slow for good, it can
+convey epilepsy promptly in guinea pigs, but transmits the acquirements
+of genius so poorly that our best student of the heredity of genius has
+to account for the frequent and remarkable deterioration of the
+offspring by a theory which is strongly hostile to use-inheritance. It
+would tend to make organisms unworkable by the excessive differences in
+its rate and manner of action on co-operative parts, and by adapting
+these parts to the total amount of nourishment received rather than to
+occasional necessity or actual usefulness. It would tend to stereotype
+habits and convert reason into instinct.
+
+How then can we rely upon use-inheritance for the improvement of the
+race? Even if it is not a sheer delusion, it may be more detrimental as
+a positive evil than it is advantageous as an unnecessary benefit; and
+as a normal modifying agent it is miserably weak and untrustworthy in
+comparison with the powerful selective influences by which nature and
+society continually and inevitably affect the species for good or for
+evil. The effects of use and disuse--rightly directed by education in
+its widest sense--must of course be called in to secure the highly
+essential but nevertheless _superficial, limited, and partly deceptive_
+improvement of individuals and of social manners and methods; but as
+this artificial development of already existing potentialities does not
+directly or readily tend to become congenital, it is evident that some
+considerable amount of natural or artificial selection of the more
+favourably varying individuals will still be the only means of securing
+the race against the constant tendency to degeneration which would
+ultimately swallow up all the advantages of civilization. The selective
+influences by which our present high level has been reached and
+maintained may well be modified, but they must not be abandoned or
+reversed in the rash expectation that State education, or State feeding
+of children, or State housing of the poor, or any amount of State
+socialism or public or private philanthropy, will prove permanently
+satisfactory substitutes. If ruinous deterioration and other more
+immediate evils, are to be avoided, the race must still be to the swift
+and the battle to the strong. The healthy Individualism so earnestly
+championed by Mr. Spencer must be allowed free play. Open competition,
+as Darwin teaches, with its survival and multiplication of the fittest,
+must be allowed to decide the battle of life independently of a foolish
+benevolence that prefers the elaborate cultivation and multiplication of
+weeds to the growth of corn and roses. We are trustees for the countless
+generations of the future. If we are wise we shall trust to the great
+ruling truths that we assuredly know, rather than to the seductive
+claims of an alleged factor of evolution for which no satisfactory
+evidence can be produced.
+
+
+THE END.
+
+RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNGAY.
+
+
+FOOTNOTES:
+
+[72] Professor Romanes had casts made of the feet of upland geese, and
+could not detect any diminution as compared with the web of other geese
+in relation to the toes.
+
+
+
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+NATURE SERIES.
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+By Sir WILLIAM THOMSON, D.C.L. LL.D., F.R.S.E, Fellow of St. Peter's
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+CHARLES DARWIN. Memorial Notices reprinted from _Nature_. By THOMAS
+HENRY HUXLEY, F.R.S.; G. J. ROMANES, F.R.S.; ARCHIBALD GEIKIE, F.R.S.;
+and W. T. THISELTON DYER, F.R.S. With a Portrait engraved by C. H.
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