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diff --git a/old/53319-0.txt b/old/53319-0.txt deleted file mode 100644 index 7e60aea..0000000 --- a/old/53319-0.txt +++ /dev/null @@ -1,11333 +0,0 @@ -The Project Gutenberg EBook of Initiative in Evolution, by Walter Kidd - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world 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. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Initiative in Evolution - -Author: Walter Kidd - -Release Date: October 19, 2016 [EBook #53319] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK INITIATIVE IN EVOLUTION *** - - - - -Produced by Thiers Halliwell, Chris Curnow and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - -Transcriber’s notes: - -The text of this book has been preserved as in the original except -for correction of some typographic errors (see below) and punctuation -inconsistencies. Italic text is denoted by _underscores_ and a caret -mark ^ precedes any superscripted character(s). Footnotes have been -numbered and positioned below the relevant paragraphs, and some -illustration captions have been moved closer to the relevant text. - -Corrected misspellings include the following: - - constitutent —> constituent - It —> If - o —> to - endotheliun —> endothelium - ecomomy —> economy - involutary —> involuntary - old factory —> olfactory - tacile —> tactile - irrevelant —> irrelevant - tranverse —> transverse - decebrate —> decerebrate - Thistleton —> Thiselton - opprobious —> opprobrious - Duputryen's —> Dupuytren's - ditēthēsis —> diēthēsis - - - - - INITIATIVE IN - EVOLUTION - - - BY - WALTER KIDD, M.D., F.R.S.E. - - - AUTHOR OF - “USE--INHERITANCE,” “DIRECTION OF HAIR IN ANIMALS AND MAN,” - “THE SENSE OF TOUCH IN MAMMALS AND BIRDS,” ETC. - - - _WITH NUMEROUS ILLUSTRATIONS_ - - - H. F. & G. WITHERBY - 326 HIGH HOLBORN, LONDON - - 1920 - - - - -PREFACE. - - -The Great War imposed on speculative biology a moratorium as in the -long vacation of lawyers, in which are causes left over to the next -term. And so the old case Lamarck _versus_ Weismann was not heard in -the Courts of Science during the war. In the present term it is due to -be heard afresh, and at some future date to come up for settlement. -The chapters that follow comprise some of the pleadings on behalf of -the plaintiff and are part of the brief of a junior counsel. This -adjective, alas! signifies not the years--for such are often old enough -to be the fathers of the leaders--but the standing and attainments of -a junior. But in the open Court of Science, and on suited occasions, -it may be the business of a junior to question, in the interests of -his client, the authority even of Attorneys-General and Lords Chief -Justice. In matters of thought and inquiry it is useless to retreat -within a stronghold and bar the gates. It may be satisfactory to -himself for one Milner to write a book on behalf of a certain body of -doctrine and call it _The End of Controversy_, but the book should -have held the sub-title _The End of Progress_. The Newtons, Pasteurs -and Darwins have seldom wielded the weapon of controversy, though the -triumph of _The Origin of Species_ would have been slower without the -aid of Darwin’s brilliant champion and candid friend. But, if the -leaders seldom need such help, for the Gibeonite it is a matter of -course and simple necessity. With all the urbanity due to the great -subject-matter should this pleasant duty be performed. Who would not -prefer to the fierce Spaniard the genial Portuguese, discussing all -subjects without rancour, and lover of bull-fights though he be, taking -care to wrap in cork the horns of his fighting bulls? - -The earlier chapters treat of the arrangement of the mammalian hair, -which has occupied my attention for over twenty years, and this -has led straight to the other subjects, because of their bearing on -Lamarckism and Initiative in Evolution. The tentative conclusions -reached years ago have been strengthened by further knowledge and -reflection, and perhaps by certain criticisms. The furrow ploughed -may have been lonely, but the pursuit has not been without the mild -pleasure of seeing fresh scattered portions of the field coming into -their natural order. The resulting state of mind resembles that of -a certain Mr. Burke recorded in the annals of a golf club, second -to none, the Ancient, and now Royal Blackheath, among whose minutes -appears the following:-- - - “20th September, 1834. - - Present, Mr. Burke, _Solus_. - - The dinner was good, wine abundant, and the utmost harmony prevailed. - The want of grouse was severely felt this day.” - -It is written on page 101 of the _Chronicles of Blackheath Golfers_. - -My debt to such writings as those of Professors Arthur Keith, Woods -Jones, Graham Kerr, and Professors Sherrington, Starling, Schäfer, -McDougall and Ward is too obvious to the reader to need more than a -bare mention. - -I have to thank one critic, Miss Inez Whipple, now Mrs. H. Wilder -Harris, for her able if hostile criticism of two former books of mine -which has been of use in this one; and Mr. R. E. Holding for good help -extending over many years in the preparation of the illustrations, and -for many a good suggestion. - - W.K. - - - - -CONTENTS. - - - CHAPTER PAGE - - I.--From Known to Unknown 1 - - II.--Review of the Position 8 - - III.--The Problems Presented 22 - - IV.--Initial Variations and Total Experience 30 - - V.--Method of Proof 36 - - VI.--Evidence from Arrangement of Hair 39 - - VII.--The Evolution of Patterns of Hair 50 - - VIII.--Can Muscular Action change the Direction - of Hair in the Individual? 64 - - IX.--Habits and Hair of Ungulates 74 - - X.--Habits and Hair of Ungulates 86 - - XI.--Habits and Hair of Carnivores 92 - - XII.--Habits and Hair of Carnivores 98 - - XIII.--Habits and Hair of Primates 103 - - XIV.--Miscellaneous Examples 115 - - XV.--Experimental 124 - - XVI.--First Summary 140 - - XVII.--Varieties of Epidermis 145 - - XVIII.--Arrangement of the Papillary Ridges 157 - - XIX.--Flexures of the Palm and Sole 170 - - XX.--The Evolution of a Bursa 178 - - XXI.--The Plantar Arch 192 - - XXII.--Muscles 200 - - XXIII.--Innervation of the Human Skin 218 - - XXIV.--The Building of Reflex Arcs 231 - - SUMMARY 257 - - INDEX 259 - - - - -LIST OF ILLUSTRATIONS. - - - FIG. PAGE - - 1 Arrangement of hair on the forearm 42 - - 2 Diagrams of hair-patterns 51 - - 3, 4, 5 Neck of horse, showing muscles and tendons 53, 54 - - 6–19 Side of neck of various horses, showing - varieties of hair-patterns 56–62 - - 20–29 Illustrations of human eyebrows, showing - muscular action and hair-direction 70–73 - - 30 Front view of horse, showing pectoral pattern 76 - - 31 Side view of horse showing hair-direction 77 - - 32, 32a Frontal region of horses, showing muscles and - hair-pattern 78 - - 33 Side view of horse, showing chief superficial - muscles 79 - - 34, 35 Side and back views of cow, showing - hair-patterns on back 88 - - 36 Lioness, showing direction of hair-streams on - muzzle 93 - - 37 Back of lion, showing hair-pattern 95 - - 38–40 Gluteal region, foreleg and chest of - domestic dog, showing hair-direction 99, 101 - - 41 Arrangement of hair on back of lemur, - chimpanzee and man 105 - - 42 _Idem_ chest 109 - - 43 Giraffe, showing hair-patterns of neck 116 - - 44 Giraffe in attitude of drinking or browsing - off the ground 117 - - 45 Bongo, showing hair-patterns of chest 119 - - 46 Kiang. Side view showing inguinal and - axillary patterns 121 - - 47 Forefoot of llama, showing hair-direction 122 - - 48 Two-toed sloth, showing action of gravity - on hair 123 - - 49 Domestic horse, fully harnessed 128 - - 50 Side view of domestic horse, showing - reversed hair due to harness 129 - - 51–58 Necks of various horses, showing reversed - hair due to collar 132–135 - - 59 Right hand, drawing of papillary ridges, - made from impressions 158 - - 60 Right foot. _Idem_ 160 - - 61–70 Hands and feet of lower animals, - showing papillary ridges 161, 163–166, 168 - - 71 Flexures on palm of right hand. - Drawing made from impression 171 - - 72–79 Flexures on hands and feet of various - lower animals 172–175 - - 80 Drawing of flexures of sole of foot of man, - young adult 176 - - - - -CHAPTER I. - -FROM KNOWN TO UNKNOWN - - -Upward--still upward--still upward to the highest! Such is the claim -of modern man for the story of himself and the lower inhabitants of -the globe. The zoologists have gone so far as to confer upon him the -surname Sapiens--Homo Sapiens. Learned indeed he is, and heir of all -the ages, but whether or not his assumed surname be warranted the -doctrine of descent with modification can never again be questioned. -The work of Darwin was crowned when he compelled a general acceptance -of that doctrine, and now the Descent of Man and the Ascent of Man -are equivalent terms for a natural process which has converted man -from a thing to a person, and is the foundation of all modern thought. -The biologist works secure in the knowledge that he is studying some -portion of a chain of life stretching back for incalculable ages, and -is not careful to produce those missing links demanded by the once -formidable foes of his fundamental principle. Haeckel may announce that -Pithecanthropus Erectus of Dubois is truly a Pliocene remainder of that -famous group of highest Catarrhines which were the immediate pithecoid -ancestors of man. This may or may not be true, but if true it makes -the descent of man from a lower stock none the surer, the increasing -verification of which is not found to rest on missing links. - -Many of the discoveries of modern science are made by proceeding from -known phenomena to the unknown, or, more precisely, from the well-known -through the little-known to the hitherto unknown. - -As to the validity of knowledge it is enough to say this--and pass -on--_all our knowledge is provisional and imperfect, and much of our -ignorance is as transient as ourselves_. - -There are two chief ways in which historians deal with their -subject-matter, though the moderns combine them. When oral tradition -gives place to written records the lineal descendant of the bards -and annalists collects his scanty authorities and compiles his story -from them from beginning to end. The Anglo-Saxon Chronicle of Bede -and Alfred, the Book of Howth, the works of Giraldus Cambrensis, the -Chronicles of Froissart and the Memoirs of de Comines were composed -in the only way that was then possible. But the muse of history -entered on a deeper and more fruitful course when about ninety years -ago the study of documents became an essential feature of historical -work. It was then that the historian grew up, entered upon his finest -inheritance and assumed his Greek title, Enquirer, Student of facts, -Man of research. He is now nothing if not a man of science as well as -of letters. With a wealth of documents within his reach so great that -the 3239 Vatican cases full of them formed by no means the richest -collection in the archives of Europe, he proceeds to read backwards -correctly what many an earlier annalist read forwards falsely. “We -are still at the beginning of the documentary age which is destined -to make history independent of historians, to develop learning at the -expense of writing, and to accomplish a revolution in other sciences as -well.”[1] - - [1] Acton. _A Lecture on the Study of History_, p. 19. - - -The Historian a Biologist. - -It is not too much to say that he who studies history, national, -political, constitutional, ecclesiastical, military or economic is as -much a biologist in the widest sense as the botanist and zoologist. -Indeed these were till recently termed students of natural _history_, -until the advance of knowledge gave us the various special groups of -workers, conveniently called biologists. Though the study of human -history by documents is an essential part of the historical method -and the student may read _his_ subject backwards, this would not of -itself warrant the technical biologist in doing so, even though he be -a child of Nature and part of her--“Nature’s insurgent son.” But some -reflection on the facts of certain provinces of science affords ample -justification for the method. It is chiefly in questions of origin -that it avails, while it fails in that form of research by experiment -which is the glory of modern science. A few examples of the process of -passing from the known to the unknown will illustrate the method. - - -Darwin. - -Much of the _Origin of Species_ and all of the _Descent of Man_ was -founded on this method; thus in the former the conceptions of struggle -took their main rise from the work of Malthus on Human Population, and -of variation from domesticated animals and plants, and this is true -also of Wallace. A mere glance at the divisions of _The Descent of Man_ -shows that it could never have been attempted in any other than the -backward way. - - -Geology. - -In their researches on the crust of the earth Playfair, Hutton and -Lyell did not pursue them by going down a coal mine till they came to -the lowest available beds and work upward from these to the highest. -Though for purposes of exposition a great geologist, as Sir Archibald -Geikie, may expound the making of the earth from the lowest to the -highest levels, and Professor Bonney tell us the _Story of our Planet_ -from beginning to end as if he had watched it unfolding, Lyell in his -_Principles of Geology_ shows how the studies of his great province -began. There we have the backward reading of its story pursued by -himself and other great ones, and where it led them. Commencing with -the Pleistocene period and passing through Neocene and Eocene periods -through the Mesozoic Era and its cretaceous, jurassic and triassic -systems to the Newer Palæozoic Era and its Permian, carboniferous, and -Devonian systems, the older Palæozoic Era and its Silurian Ordovician -and Cambrian systems, he reaches the unknown. But before all this -patient research and its record is reached he treats, as he must, of -consolidation and alteration of strata, of petrification of organic -remains, elevation of strata, horizontal and inclined stratification, -of faulting, denudation, upheaval and subsidence as they combine -to remodel the earth’s crust. The title of his classical work is -significant--_An Attempt to Explain the Former Changes of the Earth’s -Surface by Reference to Causes now in Operation_ (it may be noted that -in 1830 they were fond of capital letters and of underlining their -words). If these great men had been condemned to the sole use of the -method of the annalist in his treatment of human history, that of the -coal mine in geology, this great province of knowledge would never have -been what it is to-day. - -At this point I think it well to state that this illuminating principle -of Lyell is pursued in nearly all the matters of fact and their -interpretation contained in the following chapters, so that from time -to time I shall have to employ the verb, coined for the purpose, when I -attempt to “Lyell” them on behalf of Lamarck. - - -Anthropology. - -The anthropologist could hardly make a start with his research, if, -knowing nothing of his own anatomy, physiology, customs and beliefs, he -tried to interpret the physical features, habits, manners, customs and -rites of an African tribe. Without such prior knowledge he would find -it a profitless task to journey to the banks of the Zambesi and bring -back any intelligible history of the aborigines. If he did not know the -games of a European child how could he understand the variants of them -such as the writer of _Savage Childhood_[2] expounds so well? - - [2] _Savage Childhood_, Dudley Kidd. - - -The Sources of Rivers. - -To trace the course and source of a river is a simple task through the -work of modern geographers, and such a pursuit illustrates well the -two methods here considered, but it is doubtful if any river was ever -traced originally from its fountain head to its mouth. The backward -way of such exploration, from the nature of the case, has always been -taken, and men have traced the more or less finished products of the -lower stretches, backward, still backwards, even as in the Indus, to -the still-unknown. The earliest thinkers and seekers in the plains of -Bengal were familiar with much of their great sacred and composite -river as it flowed into its delta. Slowly, laboriously, here a little -and there a little, they learned its stupendous story. They found the -plateau of Tibet in the Himalayas where the twin-sisters, Brahmaputra -and Ganges were born, and saw how from the one high cradle they parted -on their eastward course for a thousand miles with the mountain-chain -between them, and how, coming together again, the one descending -through Assam and the other flowing through the plains, reinforced by -the Jumna, they united to form the Ganges-Brahmaputra. A great subject -indeed for the early geographer, but one which he could only follow in -the backward way. Again how well known and revered in Egypt was the -Nile for thousands of years before its source in Victoria Nyanza could -be traced, even though Nero might send his explorers as far as the -marshes of the White Nile, and Ptolemy’s search for it might lead him -to guess the riddle, and assign it to two great lakes! - - -Genealogy. - -Not many of us can trace our ancestry in the direct male line to -the 8th century by authentic and written documents as did a Hebrew -friend of mine, thus effectually meeting the doubts of a prospective -brother-in-law who asked him as to his fitness to enter a family which -was able to produce a stray peer of the realm in its roll. On the other -hand a man who has lost his parents in childhood may know nothing of -them but that his father’s name was A. Mann, and that he was buried -in a Kentish churchyard. He may go on a pilgrimage and find there -recorded the fact that A. Mann was the son of A. Mann, Gent, who came -from Northumberland. He will doubtless make another pilgrimage and find -there a large vault, and over it an imposing record of many a Mann, -and yet further he may go, and from the Heralds’ College find out the -still earlier derivation of his ancestors. - - -Detection of a Crime. - -There are two chief ways of detecting a crime. By oral evidence from -eye-witnesses or confession of the accused you may get direct proof, -though even here are pitfalls from careless and hasty witnesses on the -one hand, or on the other from a strange perversion of mind of the -confessing person which is well enough known to forensic medicine. -You may thus bring home to the accused his guilt by the method of -the annalist. Or you may employ the more common method of studying -circumstantial evidence; the story of the crime is read backwards and -a verdict of guilty is given. This is the main stuff of which the -prevalent detective story is composed. - - -A Parable. - -A plain parable may well conclude this chapter. - -As I mused on the chain of life I found a piece of whipcord which had -been lying by for twenty-five years since some of it was used for -rigging a model yacht, and this very efficient product of human art -seemed to speak to me on the subject of my musings. Perhaps if Huxley -could extract from a piece of chalk or lumps of coal two magnificent -expositions on geology and biology, this little trifle of cord might -afford a text on a way of looking at living things which should be -useful in this old case of Lamarck _v._ Weismann--and others. - -Should I learn the story of the whipcord forwards like an annalist, -or backward like a modern historian? Clearly it could be done in a -measure by either method. Here was a highly finished product of which -either might furnish the story, and of which, we may suppose, I knew -nothing. I tried the backward way, and by the aid of a needle began -to unravel it. The cord was as good as if just made, slender, strong, -twisted, with some glazing on the twisted threads. It showed three -main bundles, and each of these was composed of two smaller ones. -The substance of all these six was found when examined with a lens -to consist of minute silky fibres varying from a quarter of an inch -to an inch in length. This was all I could learn without a stronger -magnifying power or a chemical analysis, and the direct search was at -an end. I gathered since then that the first three bundles were called -“strands,” and the two composing each of these “yarns,” and that the -fibres were from a plant called hemp. This did not carry the story -deep or far, and illustrates how often in the backward method facts -have to be supplemented by inference. But I had learnt some undoubted -facts and some inferences from them nearly as certain. Some mind of -man had conceived and hands carried out the division of the bundles of -fibres into three strands, had twisted them somehow so as to reduce -their length by a quarter and yet not far enough to rupture them, and -had thus fitted them the better for their purpose by a reinforcement -of tensile strength due to the twisting. I could also see that this -same mind had seen it better to divide each of these strands into two -yarns before the final twisting, and that in framing the yarns the -silky fibres of the plant had been squeezed together by some powerful -agency and yet not disintegrated, and that the finished product had -been immersed in a protective substance which gave it a slight glaze. -In short, I, though a child in these matters, read much of the story -of this cord in terms of mind dealing with given organic matter. I may -add that I did not imagine myself a little Paley, and that I do not -intend to “take in” the reader as to the argument from design and final -causes, even though this parable may feebly resemble Paley’s study of -a watch. The conclusion was perfectly clear that certain directing -grey cells of a certain brain had interfered with and acted upon some -plastic vegetable matter, and one could at the “strand” stage, the -“yarn” stage, and the “fibre” stage see mind writ large. - - -The Forward Way. - -The limits of the former method are obvious, but I might also attempt -to follow the little story as a crime is followed and described by -eye-witnesses. So I go to an old-fashioned rope-factory and ask the -foreman questions about the making of twine, cords, ropes and cables. -He shows me bundles of hemp; he calls them Russian, Italian or -American, and goes on to tell me how the fibre is “heckled” or combed, -how “tow” is separated from “line,” and how the yarns are pressed -together and twisted, how they are at first rough and bristly, and are -then dressed, polished, and “sized” with such a starch as that of the -potato. When I proceed to ask him about the plant itself his interest -flags, and he becomes vague. He says, “You had better ask the Head, -young Mr. X., he knows these things better.” I find the Head with his -golf clubs over his shoulder and about to start on his “business,” and -he is polite, but says he knows very little about the origin of his -hemp. “You should go over the way and ask Messrs. Y. if they will let -you see the expert who advises them in their business, he will know.” -The expert is at home and kindly and fully describes to me the early -home of the wild _Cannabis Sativa_ in a moderate climate of Asia, the -rich soil it needs for its growth and the various countries of the -world into which it has been introduced; and the bast-fibres of the -bark of this plant which from remote antiquity has supplied the silky -stuff. He then tells me how the stems are dried and crushed, and then -of the important stage of fermentation or “retting” in water, how they -are again beaten in a “break,” then rubbed and “scutched,” and finally -“heckled” or combed; and, as to analytic chemistry, he tells me that -the chief constituent is cellulose. This quest is now over and I know -much I could not find out by the backward method, though the dependence -of its rival upon the presence of honest and capable eye-witnesses -is not less obvious. It is not alone in ecclesiastical history that -cheats and forgers of documents exist. In the world of Nature there -may be, for all we know, biological False Decretals that may lead -us far astray, such perhaps as Amphioxous and Archæopteryx, and the -Pseudo-Isidore who produced them may yet be discovered. - - - - -CHAPTER II. - -REVIEW OF THE POSITION - - -The modern story of the theory of organic evolution shows certain -important dates--1859, 1880, 1894, 1895, 1899 and 1909. These begin -with the _Origin of Species_ and end with the publication of a volume -in commemoration of its jubilee, when most of the leading students of -evolution united to render homage to Darwin. The year 1859 has been so -often and so worthily treated that it is enough here to say that the -fifty years between the issue of the work of Darwin and Wallace and -1909 saw a greater revolution in biology, speculative and practical, -than any period so relatively brief had ever seen. - -In the year 1880 the “coming of age” of the _Origin of Species_ was -celebrated. On the 9th of April at the Royal Institution an address -was given by the powerful friend, champion and candid critic of -Darwin, and before the scientific and educated world Huxley was able -to say with his own force and directness: “Evolution is no longer an -hypothesis, but an historical fact.” It may be noted in passing that -Darwin’s theory of natural selection is not referred to in the address. -Challenges and opposition from various quarters met this confident -claim of the formidable speaker, as doubtless he desired, but the work -of the succeeding half-century has done little or nothing that does -not establish that claim. It is hardly to be doubted that if in the -jubilee-year, 1909, Huxley had been alive on this earth, instead of -elsewhere, his eloquent voice would have been heard to declare with -emphasis equal to that of 1880: “Selection is no longer an hypothesis, -but an historical fact.” Some such statement, with the _imprimatur_ of -a great name would have removed from the jubilee-volume that slight -aspect as of a Dutch chorus[3] which is apparent in it. A remark of -Kelvin’s when he was conferring a medal of the Royal Society on Huxley -may illustrate what has been said above. He said that they must all be -thankful to have still among them that champion of Evolution who once -bore down its enemies, but was now possibly needed to save it from its -friends. It may be regretted that it was not so in 1909. - - [3] The above remark as to the jubilee-volume needs to be explained - and justified. In it there is an important essay on each of the great - provinces of Weismann, Mendel and de Vries, and in each of these the - highest living exponent speaks, Professors Weismann, Bateson and de - Vries. Bateson expresses admiration for Weismann’s destructive work, - but shows plainly that he holds it to have failed in its fundamental - purpose. Nevertheless, by a neat _tour d’addresse_ he adopts - Weismann’s uncompromising attitude on the inheritance of acquired - characters, which happens to agree exceedingly well with his own - scheme. He has but one insignificant reference to de Vries on p. 95 - where he finds help for his doctrine. - - Weismann makes no reference to Mendel or de Vries. De Vries makes - none to Weismann or Mendel, but without stating it in his essay he - is known to be in opposition to Weismann’s dogma on the inheritance - of acquired characters. These three eminent biologists would - thus seem to have worked on diverging lines. The two first agree - heartily, Weismann explicitly and Bateson by implication, as to the - forbidden doctrine, “on the ground that it closes the way to deeper - insight”--in other words their mutually destructive theories. So it - stands thus in the book--Weismann throws over Lamarck, Mendel and de - Vries; Bateson throws over Weismann (as again in 1914) and de Vries; - de Vries ignores Weismann and Mendel. - - Dr. Lock in his book on Variation, Heredity and Evolution, 1906, - says that Weismann practically ignores the evidence of Mendelism in - heredity, and adds, p. 261, “But at the next step the Mendelian parts - company with Weismann.” - - One cannot avoid noticing, incidentally, that the vast mass of work - of the biometricians led by Galton, Weldon and Professor Karl Pearson - is conspicuously absent from the book. Prof. J. Arthur Thomson says - that there should be no opposition between Mendelian and Galtonian - formulæ, “they are correlated, and ultimately they will be seen in - complete harmony as different aspects of the same phenomena. But it - is simply muddleheadedness which can find any opposition between a - statistical formula applicable to averages of successive generations - breeding freely, and a physiological formula applicable to particular - sets of cases where parents with contrasted dominant and recessive - characters are crossed and their hybrid offspring are inbred.”(a) - concerning which see the Preface to Bateson’s _Mendel’s Principles of - Heredity_, 1902, with remarks on some of the Galtonians. - - (a) _Heredity_, p. 374. - - Considering the mole-like and persistent work of the biometricians, - some who are at present keeping well-ordered lawns may find some - day a few disturbing heaps of facts. I am reminded here of an - historic duel, Oxford _v._ Cambridge, which took place soon after - the introduction of Mendel’s discoveries into England at the London - Zoological Society, when Prof. Bateson expounded them with enthusiasm - and when Weldon repelled them with cogent and incisive arguments. - The duel lasted nearly two hours and that was not too long for the - audience, but one has the impression that some of what Professor - Thomson calls muddleheadedness must have been somewhere existing. - However, the duel was fought when Mendelism was young. - - -Three Blows to Darwin. - -But other historic events are more relevant to my immediate purpose -than these. - -Three blows were delivered against Darwinism in the years 1894, 1895 -and 1899 by Prof. Bateson, Weismann, and again Prof. Bateson, under -which it seemed to reel, but from which it is more than likely it has -derived but greater strength. - - -BATESON. - -In 1894 Prof. Bateson published his large and important work, -_Materials for the Study of Variation_. As a distinguished student -and teacher of biology he found the received doctrine of evolution -in straits as regards the factor of natural selection in producing -specific differences, as indeed happened to another equally eminent man -during the next year. He was profoundly discontented as to the origin -of specific differences on the theory of direct utility of variations, -and he said “on our present knowledge the matter is talked out.”[4] -He threw over the study of adaptation “as a means of directly solving -the problem of species.” He came to the conclusion “Variation is -Evolution,” and affirmed that the readiest way of solving the problem -of evolution is to study the facts of variation. Hence arose this -notable book, and hence one of his trenchant statements to the effect -“that the existence of new forms having from their beginning more or -less of the kind of perfection that we associate with normality, is a -fact that once and for all disposes of the attempt to interpret all -perfection and definiteness of form as the work of selection,”[5] -and “Inquiry into the causes of variation is as yet, in my judgment, -premature.”[6] It will hardly be denied that a work which contained -such statements as these from such a source seemed momentous in its -influence on the fate of Darwin’s theory. Prof. Bateson yielded to -none in his loyalty to Darwin, as far as he knew himself, and here he -is as candid as Huxley, and he declares that in his treatment of the -phenomena of variation is found nothing which is in any way opposed -to Darwin’s theory. The shade of Darwin might nevertheless have -looked with some misgiving at this man over against him with a drawn -sword in his hand, and have asked gently, “Art thou for us or for our -adversaries?” Prof. Bateson’s work chiefly requires to be considered -here because to any reader of it there must come the conviction on -the one hand of Prof. Bateson’s merits and power, and on the other of -his limitation as a student of organic evolution. In 1894 is evident -already an exclusive attention to structure rather than function, -to anatomy than physiology; the anatomical leaven in doctrine has -leavened the whole lump. For him physiology of animals and plants does -not exist, or at the best is the outcome of structures which arise -through variation and selection. This, if I may say so, is as much his -strength as his weakness. There have been other great biologists, such -as Geoffrey Saint-Hilaire and Richard Owen, of whom this is true. If -that were all one would not wish the reader to be troubled with any -criticism of one’s betters, indeed such remarks as are here made do not -amount to criticism at all, but just plain text-book statements. It is -also evident that the outlook of Prof. Bateson was being prepared for -a revelation which had not yet come, in which he took a prominent, if -not dominant part, I mean the great rediscovery of Mendel’s work by -de Vries, Correns and Tschermak and himself in England. His keen and -close attention to anatomical structures was preparing his mind for the -germinal conceptions of unit-characters, dominance and segregation. -The intensive cultivation of the fertile field of genetics proceeded -apace, and Prof. Bateson in his contribution to the jubilee-volume of -1909 betrayed the trend of his devotion to a system of _distribution_ -rather than formation of the qualities of an organism. The organism as -an historical functioning, striving being, had receded once for all -from his vision. He hazarded the suggestion in _Heredity and Variation -in Modern Lights_ that “variation consists largely in the unpacking -and repacking of an original complexity,” and that “it is not so -certain as we might like to think that the order of these events is not -predetermined.” Incidentally one may remark that, _malgré lui_, Prof. -Bateson stands forth as a modern Paley as does Weismann in his great -rival and opposing scheme. It is true that he says “I see no ground -whatever for holding such a view, but in fairness the possibility -should not be forgotten and in the light of modern research it scarcely -looks so absurdly improbable as before.” Having drawn the sword he -threw away the scabbard in 1914 when he occupied the presidential chair -of the British Association of Science at Melbourne and Sydney. He had -said in 1894 in his book on variation as stated before, “Inquiry into -the causes of variation is as yet, in my opinion, premature,” and -then in 1914 at Melbourne, after twenty more years of study of the -subject in the Mendelian direction, “It is likely that the occurrence -of these variations is wholly irregular, and as to their causation _we -are absolutely without surmise or even plausible speculation_.” (my -italics).[7] So, on this fundamental point, he stands where he did when -he began the study of variation, but apart from this point he again -threw out his suggestion of 1909 as to the unpacking and repacking of -an original complexity. At Melbourne he said, “Lotsy has lately with -great courage suggested to us that all variation may be due to such -crossing. I do not disguise my sympathy with this effort.”[8] _All -variation!_ He said later, “In spite of seeming perversity, therefore, -we have to admit that there is no evolutionary change which in the -present state of our knowledge we can positively declare _not due to -loss_.”[9] (Italics mine.) These two statements of 1914 are enough to -show that the biologist of 1894, 1899, 1909 and 1914 has evolved in -a definite line, and it is to his honour that he has remembered “to -thine ownself be true.” But he is not so true to himself in his scorn -of those who propound theories. For myself I would give little for -the biologist who did not hold or propound some theory. What was the -penultimate and stirring message of the gifted G. B. Howes? “We live -by ideas, we advance by a knowledge of the facts.” The self-denying -ordinance affirmed and reaffirmed by Prof. Bateson is not observed -even in the Melbourne and Sydney addresses. In the former, he says -“at first it may seem rank absurdity to suppose that the primordial -form or forms of protoplasm could have contained complexity enough to -produce the divers types of life,” and asks us to open our minds to -this possibility. Again “I have confidence that the artistic gifts of -mankind will prove to be due not to something added to the makeup of an -ordinary man, but to the absence of factors which in the normal person -inhibit the development of these gifts.” And at Sydney, “Ages before -written history began, in some unknown place, plants, or more likely a -plant of wheat lost the dominant factor to which this brittleness is -due, and the recessive thrashable wheat resulted. Some man noticed this -wonderful novelty, and it has been disseminated over the earth. The -original variation may well have occurred once only in a single germ,” -and “so must it have been with man.”[10] - - [4] _Materials for the Study of Variation_, p. 5. - - [5] _Op, cit._, p. 568. - - [6] _Op. cit._, p. 78. - - [7] _Nature_, 1914. - - [8] _Op. cit._, Aug. 20th and Aug. 27th, 1914. - - [9] _Nature_, 1914. - - [10] _Op. cit._, 1914. - -These are three stupendous stretches of imagination and theory in one -address, which would have been the poorer if they had not overcome -the accomplished speaker’s dislike of the theories--of others. If -they are not ideal constructions of a high order I do not know the -meaning of that term. They are worthy of Weismann the Prince of ideal -constructionists. Prof. Bateson might indeed be another Newton with his -_Hypotheses non fingo_. - -Turning to another important biological doctrine one can see what it -may be legitimate to call a bi-phyletic parallelism in the biological -make-up of Prof. Bateson. Again is seen consistency of view and loyalty -to his first love. Two references from these addresses will be enough -to introduce the point. - -At Melbourne, “We thus reach the essential principle that an organism -cannot pass on to offspring a factor which it did not itself receive in -fertilization.”[11] - - [11] _Op. cit._, 1914. - -At Sydney, “The factors which the individual receives from his -parents, and no others, are those which he can transmit to his -offspring”[12]--in other words the doctrine of the inheritance of -acquired characters is estopped. As to this he speaks in 1909 more -doubtfully on p. 90 and on p. 95 almost dogmatically.[13] There is just -a convenient haziness of meaning in the term “factor” with which some -play might be made, but, taking it to mean what the context indicates, -an acquirement made by the individual during its personal life, we have -pretty clear evidence that Prof. Bateson will have nothing to do with -the inheritance of acquired characters as that doctrine is understood -by the unsophisticated biologist. This opposition should be counted -unto him for righteousness rather than the reverse, for it falls into -line with his life’s work to which he has given of his best.--_Vestigia -nulla retrorsum._ The point reached here which concerns my purpose is -that the orthodox Mendelian still knows nothing of the cause or origin -of variation, and will have none of Lamarck. - - [12] _Nature_, 1914. - - [13] _Darwin and Modern Science._ - -This consideration of Prof. Bateson’s work of a quarter of a century -has been necessary for showing how the work of Weismann and himself -diverge gravely and yet meet at one point, and the year 1899, being -linked with 1894, has been taken out of its chronological order. - -It may be permitted perhaps to say respectfully to the Mendelians in -the words of the dying father in the fable, “Dig, my sons, dig in the -vineyard.” If they follow still the course of the sons they may find -more gold than they have found already and perchance that which is -better than gold. But they will produce from it nothing that is not -there. - - -Two Parables. - -Here gentle reader (I seem to remember this style of address in -the stories of our youth) pause with me in a little oasis of the -desert-stage of our journey, and brush off some of the dust, while I -briefly narrate two incidents, but I pray you also not to leave me in -the midst of them so that you may escape the next short stage. - - A traveller, small and insignificant, armed only with an oak cudgel, - was passing alone through a South American forest. As he trudged - forward he noticed at a certain point in the path (shall we call it - 1894–1899?) that a jaguar was watching him and was about to break his - truce with man. He turned off to the right and there he saw a puma - and this too seemed to meditate evil. He hastened forward just in - time as his two enemies sprang at him, and these two near relatives - were locked in mortal grip--and so he passed on safe! - -The reader, naturalist or layman, can point the moral for himself. - - At the battle of Trafalgar, while fighting was in full progress on - one of the ships, some sailors were occupied in throwing overboard - the bodies of those who had been killed. A poor Scotchman badly - wounded and hardly conscious was taken up by two seamen, an - Englishman and an Irishman, and as they were about to throw him - overboard his feeble voice was heard to say “I’m no deed yet.” - “What’s that?” said the Irishman. “I’m no deed yet”; “Arrah, the - doctor said he was dead, over wid him,” said the Irishman. - - -Weismann. - -During the period 1894–1899 there was a dramatic proclamation on the -part of one of the greatest living biologists, which was, in the cosmos -of biology, what the Proclamation of the Empress-Queen of India was in -1876, and it is not out of place to remind the reader that the fates -of the two Imperial utterances have been somewhat different. In 1895 -Weismann issued his official statement of doctrine which was to crown -the work of his life, an essay on Germinal Selection. From Freyburg -in November, 1895, he wrote a preface to his address delivered on -September 16th in that year to the International Congress of Zoologists -at Leyden. This formed an epoch in biological thought and there lived -none so well qualified as Weismann to stand forth as its interpreter. -The well-translated, forcible language, and lucid thought leave the -reader in no manner of doubt as to his meaning. It took a wider form -in his final book on the Evolution Theory, but the germinal and -essential thoughts of the latter were contained in the former. From -1895 onwards the praise of Weismann was in all the churches. Probably -no modern worker in the fields of heredity and evolution has done so -much as Weismann towards raising great issues and removing some ancient -misconceptions; but it is one thing to raise great issues and another -to solve them. In this he has signally failed, nevertheless biological -theory would be the poorer if he had not made the attempt. Reflection, -the work of other biologists, and the remorseless hand of time have -shaken the edifices then raised. I will here only bring forward a few -of the most illuminating passages of the 1895 essay, and then refer to -the handling of Weismann’s work by Romanes. - -This trenchant essay contains fifty-seven pages, of which reasoning -forms the greater part. As to the facts it might well pass for an -essay from Professor Poulton’s pen, for Weismann’s special province -of insects occupies nearly all the evidence from facts. Outside this -highly specialised group there are exactly fifty-three lines, or one -and a half pages, which deal with other animal groups, and there are -four casual allusions to plants occupying twelve lines in all! In the -essay of 1909 on the Selection Theory this treatment of animated life -in the world is improved upon and thirteen out of its forty-seven pages -refer to animals outside his favourite group of insects. Such exclusive -dealing with these little things does not commend the reasoning, at any -rate to a neo-Lamarckian; such a circle is too select for him. - - -Weismann’s Twelve Points. - -The most striking remarks from the 1895 essay on germinal selection -are:-- - -1. “The real aim of the present essay is to rehabilitate the principle -of selection. If I should succeed in reinstating this principle in its -imperilled rights, it would be a source of extreme satisfaction to -me.”[14] - - [14] Preface to _Germinal Selection_, 1895, p. xii. - -2. Speaking of the whole theory of selection he claimed to have -found a position “which is necessary to protect it against the many -doubts which gathered around it on all sides like so many lowering -thunder-clouds.”[15] And he speaks on page 26 of “the flood of -objections against the theory of selection touching its inability to -modify many parts at once.” - - [15] p. 38. - -Thus Weismann stood forth to defend the crumbling edifice of Darwinism -and threw his shining sword into the scales, a scientific Athanasius -“contending for our all.” Again is seen a friend of Darwin from another -camp than that of Mendel, whose support needs to be received with some -caution. _Toujours en vedette_ is a useful rule. - -3. Speaking of adaptedness in animated nature he says, “We know of -only one natural principle of explanation for this fact--that of -selection.”[16] - - [16] p. 43. - -4. “Germinal selection is the last consequence of the application of -the principle of Malthus to living nature.”[17] - - [17] p. 43. - -5. “Without doubt the theory (Germinal Selection) requires that the -initial steps of a variation should also have selective value.”[18] - - [18] p. 38. - -6. “Something is still wanting in the theory of Darwin and Wallace -which it is obligatory on us to discover if we possibly can. We must -seek to discover why it happens that useful variations are always -present.”[19] - - [19] p. 15. - -7. “It is impossible to do without the assumption that the useful -variations are always present, or that _they always exist in -a sufficiently large number of individuals for the selective -process_.”[20] - - [20] p. 14. - -8. “_Some profound connexions must exist between the utility of a -variation and its actual appearance, or the direction of the variation -of a part must be determined by utility._”[21] - - [21] p. 18. - -9. That “germinal selection performs the same services for the -understanding of observed transformations ... that a heredity of -acquired characters would perform without rendering necessary so -_violent an assumption_!”[22] (Italics mine.) - - [22] p. 40. - -10. Weismann speaks warmly of Professor Lloyd Morgan for his caution -and calmness of judgment but complains of him that he “has not been -able to abandon completely the heredity of acquired characters.”[23] - - [23] p. 56. - -11. As to passive effects of environment, etc., he says “the Lamarckian -principle is here excluded _ab initio_.”[24] - - [24] p. 11. - -12. “It seems to me that a hypothesis of this kind (Lamarckism) has -performed its services and must be discarded the moment it is found to -be at hopeless variance with the facts.”[25] - - [25] p. 17. - -I have only to add here that several years ago I wrote to Weismann -drawing his attention to some facts I had observed which seemed to me -to be instances of use-inheritance, and I received a reply in polite -but brief and Prussian terms to the effect that the facts referred to -must be capable of some other interpretation, for _the machinery for -their transmission did not exist_. - -Each of these twelve quotations from Weismann’s essay is important from -the present point of view, and shows how far neo-Darwinians are likely -to promote the greater glory of Darwin, and though more than a quarter -of a century elapsed between this essay and his death Weismann was not -the man to have repudiated any of these strong statements. - - -Lighthouse Value. - -I hope at this point a small digression is not out of place in order -to introduce an aspect of Weismann’s work which is not usually -appreciated. A child is aware of the great and lesser lights that -rule the day and night, but for modern man these are not sufficient. -Accordingly he has invented from immemorial times his oil lamps, -rushlights, tallow and wax candles, gas and electric light for the -illumination of his streets and houses. Prehistoric man did not seem to -need them, as he thought. These useful examples of applied knowledge -were obviously brought into use for showing man better where he was -going and where to go, what he was doing and what he wished to see. I -hope this trite remark may be pardoned, for there is another form of -light which suits my purpose of illustrating the aspect of Weismannism -referred to above, that is the light of a lighthouse. The ancients in -their crude way saw the need for this and as far back as the days of -Ptolemy II. a tower to give light was erected on the island of Pharus, -off the Egyptian coast, and it was called a _pharos_. Man found it -necessary, as navigation and seafaring advanced, to use this principle -more and more, and on headland, sandbank and rugged coast has built -noble structures to aid the sailor in his dangerous course. The oldest -and finest of these in Great Britain is the Eddystone lighthouse, built -first in 1695 by Winstanley and finally by Smeaton in 1756–9. For what -reason is a lighthouse built and placed where it is? For the precisely -opposite reason to that of the domestic candle. While this shows you -where to go and how better to do your immediate business, a lighthouse -is for the main purpose of showing a mariner where he should _not go_. -It has no relation to adornment or pleasure. It does not invite you to -come in your vessel and admire it. It tells you to go away and avoid -the sunken rock or treacherous sands. - -I submit here the suggestion with all deference, that the final work -of Weismann has lighthouse value of a high order, as to the _modus -operandi_ of evolution. His greatness as a biologist, his candour and -skill in dialectics, have built up a veritable lighthouse which may -usefully warn the seeker after the path of evolution that he must turn -elsewhere if he would not founder upon a reef of facts. - -The two great contributions to evolutionary thought that Weismann has -made should be considered separately, the theory of germ-plasm and that -of evolution, though the latter seems to be the necessary outcome of -the former. But the truth of Weismann’s view of heredity does not of -necessity require the error of his theory of evolution. - - -Romanes on Weismann. - -For this study the examination of Weismannism by Romanes published in -1893 is of great value. I need only refer here to the main conclusions -of that lucid and learned examination. - -Weismann’s work on the germ-plasm in pursuance of a theory of heredity -is pronounced by Romanes to have remained up to 1893 substantially -unaltered, though largely added to in matters of detail, and at the -present time as far as I gather from a study of the more recent -literature this theory holds the field or at least a commanding -position in it.[26] Originally he held that the germ-plasm possessed -_perpetual_ continuity since the first origin of life, and _absolute_ -stability since the first origin of sexual propagation, but he has -shown himself willing to surrender the first postulate, and has himself -altered the second. As it stands now it must be admitted that the -continuity of the germ-plasm is an interrupted continuity with the -appearance of every inherited change; the continuity is theoretical, -not actual, and the stability of the germ-plasm is not absolute but of -a high degree. We can thus see in the story of this original theory of -heredity the lighthouse value of the _pharos_ of Ptolemy II. - - [26] Romanes, _Examination of Weismannism_, p. 115. - - “It is doubtful if anything better as to Weismann’s theory of - heredity can be said to-day than Romanes said in 1893, and inasmuch - as these two latter or distinctive postulates are not needed for - Weismann’s theory of heredity, while they are both essential to his - theory of evolution, I cannot but regret that he should have thus - crippled the former by burdening it with the latter. Hence my object - throughout has been to display, as sharply as possible, the contrast - that is presented between the brass (“iron” preferably) and the clay - in the colossal figure which Weismann has constructed. Hence also - my emphatic dissent from his theory of evolution does not prevent - me from sincerely appreciating the great value which attaches to - his theory of heredity. And although I have not hesitated to say - that this theory is, in my opinion, incomplete; that it presents not - a few manifest inconsistencies, and even logical contradictions; - that the facts on which it is founded have always been facts of - general knowledge; that in all its main features it was present to - the mind of Darwin, and distinctly formulated by Galton; that in so - far as it has been constituted the basis of a more general theory - of organic evolution it has proved a failure; such considerations - in no way diminish my cordial recognition of the services which its - distinguished author has rendered to science by his speculations - upon these topics. For not only has he been successful in drawing - renewed and much more general attention to the important questions - touching the transmissibility of acquired characters, the causes of - variation, and so on; but even those parts of his system which have - proved untenable are not without such value as temporary scaffoldings - present in relation to permanent buildings. Therefore, if I have - appeared to play the _role_ of a hostile critic, this has been only - an expression of my desire to separate what seems to me the grain of - good science from the chaff of bad speculation.” - -It is far otherwise with Weismann’s theory of evolution. Romanes shows -that with the removal of its essential postulate the absolute stability -of germ-plasm, Weismann’s theory of evolution falls to the ground. He -has indeed surrendered much in his later building, his second temple -of Solomon, and prominent among these was the claim that the only -causes of individual variation and of the origin of species in the -uni-cellular organisms are the Lamarckian factors, just as in the -multicellular _the only cause of these is natural selection_. Thus we -see standing at the critical date, 1892, the first Eddystone lighthouse -of Winstanley, a greater and more important structure than the old -pharos. - - -Germinal Selection. - -It can hardly be doubted that one of the “thunderclouds” threatening -Darwinism, of which Weismann spoke in 1895, was this examination of -Weismannism by Romanes. As the case stood then some fresh strategy -was needed if victory for Darwin was to be won, at least so the great -leader said. It must be remembered that it was the _personal_ selection -of Darwin which was held to be in danger. Accordingly germinal -selection was brought forth and remained the basis of Weismann’s later -_Evolution Theory_ of 1904 and 1909. Romanes did not live to see or -assist in the disproof of this ambitious piece of work so that his -“examination” is so far incomplete. - -The position of germinal selection is defined in Weismann’s statement -that “it is the adaptive requirement itself that produces the useful -direction of variation by means of selectional processes within the -germ.” Here it is in a nutshell. The theory itself is consistent, -and clearness has been added to the earlier evolution theory by the -claim that a struggle for nutriment occurs within the fertilised ovum -between the innumerable determinants of the different parts, so that -maintenance or victory over weaker determinants takes place. Thus we -have a survival of the fittest _in petto_ in the germ analogous to -that of the individual organisms as we see them. There is of course -a resemblance here to the cellular or histonal selection of Roux, -but his doctrines are not weighted with the intolerable dogma of the -non-inheritance of acquired characters. But ultimately this conception -of germinal selection has to come down and bow to the tribunal of -facts, and the remark of Weismann on Lamarckism which has been -already quoted, “It seems to me that an hypothesis of this kind has -performed its service and must be discarded the moment it is found -to be at hopeless variance with the facts,” confronts the consistent -Weismannian. And I venture to say here that germinal selection is -represented by the Eddystone lighthouse of 1756–9 erected by Smeaton. - -The grounds for this statement are afforded by numerous facts and -experiments, to which in the later chapters I propose to add a few -fresh ones, and by a growing body of opinion and authority in favour of -Lamarckian factors in evolution. - -Three “lighthouses” of this metaphorical sort have thus been afforded -by the work of Weismann, represented by the Pharos of old, Winstanley’s -Eddystone lighthouse and that of Smeaton. - - -Authority. - -We have then Weismann and Professor Bateson definitely ranged against -the position taken in this volume as to a cause or origin or variation -and the inheritance of acquired characters. To these we must add the -great weight of Sir E. Ray Lankester’s opinion lately given in a reply -to Professor Adami that “it is very widely admitted (more correctly -“claimed”) that no case of the transmission of what are called acquired -characters from parent to offspring has been demonstrated in so far as -those higher animals and plants which multiply by means of specialised -egg-cells and sperm-cells are concerned.” - -It is not necessary to mention more than these “three mighties” of the -biological world. - -Many others such as Prof. J. Arthur Thomson and Prof. W. K. Brooks, -of Johns Hopkins University, are still unconvinced as to Lamarckian -factors and ask for more evidence, and they have many to support them -in their opinion and claim. There is often a tone of weariness, as well -as wariness in their remarks on the matter. - -In favour of the neo-Lamarckian position, with which stands or falls -the suggested cause of variation, there is a growing body of opinion, -with the mention of which I conclude this review. - -1. The accomplished writer of _Form and Function_, Mr. E. S. Russell, -says the theory of Lamarck “although it had little influence upon -biological thought during and for a long time after the lifetime of -its author, _is still at the present day a living and developing -doctrine_.”[27] - - [27] p. 215. - -2. Sir Francis Darwin from the Presidential Chair of the British -Association of Science in Dublin in 1908 proclaimed his adherence to -the mnemonic theory of heredity, foreshadowed by Samuel Butler and -inaugurated by Semon, a condition of which is that acquired characters -are inherited. This caused much stir in the camp of “our friends the -enemy.” - -3. Observations and experiments at variance with germinal selection and -its negative presupposition have been rapidly accumulated from the work -of botanists and zoologists who were prepared to appeal to the tribunal -of natural processes; though Weismann and some of his followers, with -some reason, look upon the evidence from plants as a weak link in -the chain of evidence. Many of the observations and experiments are -well-known and only a mere mention of them need be made here, they are -such as Mr. J. T. Cunningham’s observations on the effect of light on -the under surface of flounders, Kammerer’s on the changes in the colour -of salamanders to surrounding objects, and others by him on certain -amphibia and reptiles especially _alytes_ held by Professor McBride -to be convincing, though the latter are to be repeated at the London -Zoological Society’s gardens and are therefore _sub judice_--others -on brine-shrimps, on the effects of change of food on bee-grubs and -tadpoles, and of the change of level of environments of certain -cereals--others by Henslow on plants which have never been refuted, and -many by the late Prince Kropotkin. The latter have appeared at length -in certain issues of the Nineteenth Century in September 1901, March -1912, October 1914, and the last in January 1919, and they deal both -with plants and animals, and are too numerous to be mentioned here -individually. - -Again, Professor Dendy as President of the Zoological Section of -the British Association of Science in September, 1914, devoted most -of his address to the subject of Lamarckism and firmly claimed as a -necessary factor of evolution “the direct response of the organism to -environmental stimuli at all stages of development, whereby individual -adaptation is secured, and this individual adaptation must arise -again and again in each succeeding generation.” He also maintains -this position in several passages in his important work _Outlines of -Evolutionary Biology_ published in 1912. - -A statement by Professor Bower, President of the Botanical section -of the British Association of Science in 1914 should also be noted: -“I share it (the doctrine in question) in whole or in part with many -botanists, with men who have lived their lives in the atmosphere of -observation and experiment found in large botanical gardens and not -least with a former President of the British Association, viz., Sir -Francis Darwin.” - -Professor Adami, in 1917, published an original work called _Medical -Contributions to the Study of Evolution_ in which from his extensive -knowledge of the subject he deals with evidence of inheritance of -acquired characters in lowly organisms as well as higher animals from -the point of view of pathology. - -Enough has been stated here to show that the dogma of Weismann or -Lamarckian factors in organic evolution, _quâ_ authority, has been in -poor case during recent years, and it remains for me now to add my -small quota of the authority of facts. - - - - -CHAPTER III. - -THE PROBLEMS PRESENTED. - - -In his classical work on Heredity, Professor J. Arthur Thomson exhausts -the evidence on Lamarckism available then (1908) in a manner worthy of -the summing-up of an English judge. This is presented to the jury of -the biological world and they are still considering it. Their verdict -and his sentence are not yet delivered, and it may be they will still -be long delayed. One might almost use the words of Professor Bateson, -previously quoted, “on our present knowledge the matter is talked out.” - -I will make one prophecy in this volume and predict that the fourth -edition of this work in 1930 will contain the verdict of the jury and -sentence of the distinguished judge to the effect that in the case -Lamarck _v._ Weismann the plaintiff has won. As in the Great War the -Old Contemptibles held their line with the utmost difficulty against -the disciplined hosts of the greatest army ever known till then, and -yet the latter found their First Battle of the Marne, so perchance it -may be in the present struggle. - -I introduce this chapter with an important passage from the above work -on the _Logical position of the Argument_, in which the two possible -methods of establishing the affirmative position of Lamarck are given; -these are, first, actual experimental proof of transmission, and, -second, a collection of facts which cannot be interpreted without -the hypothesis of modification inheritance. The words are:[28] “_The -neo-Lamarckians have to show that the phenomena they adduce as -illustrations of modification-inheritance cannot be interpreted as the -results of selection operating on germinal variations. In order to do -this to the satisfaction of the other side, the neo-Lamarckians must -prove that the characters in question are outside the scope of natural -selection, that they are non-utilitarian and not correlated with any -useful characters--a manifestly difficult task. The neo-Darwinians, on -the other hand, have to prove that the phenomena in question cannot -be the results of modification-inheritance. And this is in most cases -impossible._”[29] - - [28] _Heredity_, 1908, p. 240. - - [29] I prefer to state the above passage rather than that on - page 179, which is as follows: “The precise question is this: - _Can a structural change in the body, induced by some change in - use or disuse, or by a change in surrounding influence, affect - the germ-cells in such a specific or representative way that the - offspring will through its inheritance exhibit, even in a slight - degree, the modification which the parent acquired?_” (Italics in - original). The question is very precise and important, but I employ - that given above in preference as lending itself better to the line - of inquiry followed here. - -I have placed this passage in italics because of its importance from -the point of view of the two problems which I am presenting and would -remark here that if only all the writers had used Professor Thomson’s -term “modifications” instead of “characters” in the statement of this -doctrine much confusion and evasion of plain facts would have been -avoided, and yet such workers as the Mendelians, if deprived of their -clear-cut term “characters” would have been less able to carry on their -studies. To this point of terminology I refer below.[30] - - [30] The term “character” derives both from its etymological origin - and its application to biology a double-edged quality. This is of - great value to the study of Mendelism which can only or mainly - work with “unit-characters,” and it also serves the Weismann dogma - well. In both cases the term obliterates the conception of initial - variation, and while serving the purposes of these two great schools - of thought it directs attention away from the early minute and - unimportant stages by which many _germinal_ variations may have - arisen. If it had been coined for the purpose, which it was not, it - would have been a remarkable instance of polemic cunning. It will - be evident in the course of this study of initial variation, that - the accredited and general use of the term “character” begs the - question far too manifestly for the general use of biologists. If - it be retained for the neo-Darwinian and Mendelian provinces there - is nothing to say against it, but I adopt here with pleasure the - alternative term, often used by Professor Thomson, “modification.” - This is wide enough to include the more clear-cut “character” so - long as one makes it clear that the latter is one of the germinal - variations. Further, I hold that his use of the term “transmission” - instead of “inheritance” is the more useful for a wide range - of phenomena. As far as possible I shall employ the expression - “transmission of modifications,” instead of that well-worn but often - sophisticated expression “inheritance of acquired characters.” This - has been subjected by Sir Archdall Reid and Dr. Dixey, to say nothing - of others such as Mr. George Sandeman, to a somewhat bewildering - analysis. Thus the former says, “It follows that the so-called - “acquirements” are innate and “inherited” in precisely the same - manner as the so-called inborn characters.”* Dr. Dixey admits “that - all characters are both acquired and innate”** and goes on to say - that the accepted meaning of the terms was vague, that it led to - confusion, and that it ought to be dropped. For this remark of Dr. - Dixey one may be thankful, but of my friend Sir Archdall Reid I would - ask what he is doing in this galley? - - * _Nature_, Vol. 77, Jan. 30th, 1908, p. 293. - - ** _Nature_, Vol. 77, Feb. 1908, p. 392. - - Sir E. Ray Lankester in a letter in _Nature_, 21st March, 1912, - dissented from the mode of treatment of this point by Sir Archdall - Reid and presumably also by Dr. Dixey in the words “It is not, I - think, permissible to say that the normal characters which arise in - response to normal conditions are with equal fitness to be described - as ‘acquired.’” As to what is a normal character and what are normal - conditions there may be much reason for difference of opinion, but I - have said enough of this discussion to show that the terms “acquired” - and “character” would afford a biological Pascal some such food for - criticism as did the term “probable” in his _Provincial Letters_. The - less these two terms are employed the less misunderstanding there - will be of certain problems. - - It has been held that “discussing words is often indescribably - tiresome, but it is better than misunderstanding them,” which is most - true. - -In a world teeming with the life of plants and animals, and in the -branch of science which seeks to interpret them, where we enter -upon the unknown much sooner than in any other sphere of science, -Weismann has set out to prove or maintain the most stupendous negative -ever framed by the human mind. It would require generations of men -to _prove_ this negative, if it were probable, and his case rests -mainly on the assumed weakness of his opponents. So what is needed -and demanded from the neo-Lamarckians is the production of a few -well-attested and verified facts, and, as he admits himself, then it -must follow as the night the day that his followers will surrender -his characteristic dogma. The more cautious leaders and teachers of -the day say that this has not taken place and ask for facts, more -facts and still more facts, and this attitude is both judicious and -judicial, for example in a teacher so eminent as Professor J. Arthur -Thomson. Scientific men, in such a position as he occupies with grace -and distinction, owe a serious debt of loyalty to ultimate truth and -to the inquiring minds of the young students of to-day and to-morrow. -Those who are in a position of inferior responsibility and honour, -and more freedom, just rank and file members of the Commons’ House -of Parliament, may be pardoned if they do not exhibit an excess of -deference to authority and if they think for themselves. - - -Two Questions. - -There are before the Scientific jury to-day two very vivid questions. - - (1) Can modifications in the structure of an individual organism, - occurring as a result of its experience, be transmitted? - - (2) What is the cause of variation? - -If, as Weismann taught, the answer to No. 1 is in the negative, there -is little use here in trying to answer No. 2, for from the present -point of view the two stand or fall together in the study of Initiative -in Evolution. Such _distributional_ answers to No. 2 as Bateson and de -Vries may offer do not concern my purpose. - -If No. 1 be answered in the affirmative it is sufficient for the -purpose of treating initial variations from the Lamarckian standpoint, -for it is hardly conceivable that Nature would neglect so simple and -obvious a method of leading upwards and onwards the organisms that -inhabit a changing world. - -It is very clear from what is written on the subject of evolution -to-day that a _point d’appui_ in the process is earnestly desired -by many workers and that Weismann’s dogma stops the way. A very -significant and important remark is made by Professor W. McDougall -in his small book on Physiological Psychology, with reference to the -inheritance of acquired characters, that it is a “proposition which -most biologists at the present time are inclined to deny because they -cannot conceive how such transmission can be effected. Nevertheless the -rejection of this view leaves us with insuperable difficulties when we -attempt to account for the evolution of the nervous system, and there -are no established facts with which it is incompatible.”[31] I am aware -that in the scheme of observed nature there is evidence of no iron -necessity, that the convenience of psychologists should be provided -for, and they, like others of us, have to do the best they can with the -tools and the materials which exist, and I agree with Professor Thomson -in his remark on _Misunderstanding No. 1_, “that our first business -is to find out the facts of the case, careless whether it makes our -interpretation of the history of life more or less difficult,”[32] -but I am persuaded that he will not treat lightly _such_ a statement, -from _such_ a source, on _such_ a subject as that I have quoted from -Professor McDougall. As to his second statement on the same page -“that in the supply of terminal _variations_, whose transmissibility -is unquestioned, there is ample raw material for evolution” it is -important as an opinion, and no more, and there is in the present -connection, an elusiveness about it which prevents one allowing it to -pass. It should be noted that stress is laid upon the term “variations” -and from the context this means congenital full-blown “characters” -such as those that Weismann says are provided in the germ guided by -selection. At any rate, initial modifications are not signified by -Professor Thomson’s remark. So for _evolution_ of forms of life it is -possible the assertion may be true, but apart from distribution of -variations, under the process called amphimixis, some starting point is -required for the initial and wholly useless stages of many variations. -These may or may not become “characters” or adaptive. - - [31] _Physiological Psychology_, 1911, p. 156. - - [32] _Op. cit._, p. 179. - - -What the Problems are not. - -The ground may be cleared here by saying what our problems are not. -There is no question as to whether Lamarckism or Darwinism represents -the predominant partner in the story of life; there is no question -of the “relative importance of natural selection and the Lamarckian -factors in organic evolution,” though such a question may arise when -once Lamarckism has received its passport from the authorities; but the -time is not yet. Nor is it a question as to the reason why adaptive -modifications are so constantly present in the germ. It is not a -question of Nature _or_ Nurture, but perhaps may be found to be a study -of Nature _and_ Nurture. It is not a question of Mendelian analysis, -nor as to the distribution of either mutations on the one hand, nor of -minute fluctuating variations on the other. The problems are therefore -limited in scope and ambition, and are none the worse for that, as -being better open to correction or support. - - -The Problems Considered. - -It seems but natural to most persons who contemplate with any care the -ever-changing and progressive drama of life in plants and animals that -unquestionably the _dramatis personæ_ by their individual response to -the environments and exercise of their functions must contribute a -share, however small, to their offspring. When first this view presents -itself to their minds they resent as “unnatural” any other possibility. -But, alas! they find that such a conclusion is not permitted in those -regions where alone the white light of science shines. Here the writ of -_a priori_ does not run. The spirit of inquiry makes its challenge to -every presupposition and every assertion in its province--even those -of current science. I have shown that this particular assumption of -the natural man was firmly challenged by Weismann, who was not the -first, but the greatest, biologist to teach that modifications are -not transmitted. Accordingly, agreeable and convenient as it would be -to assume the Lamarckian hypothesis as a working one, it needs in the -present day to be supported by evidence before this can be allowed. -Facts, then, against Weismann’s dogma are demanded and of such a kind -as will satisfy so powerful an advocate of his own views. In passing -it may be remarked again that there is nothing so misleading as facts, -except statistics, and for both sides to bear in mind the warning of a -French writer that in such inquiries as this we should be careful lest -we find the facts for which we are looking. - -To meet the conditions laid down in Professor Thomson’s Canon I -propose to describe certain phenomena which are adduced as instances -of modifications in certain mammals whose structure and mode of life -are intimately known, and whose ancestry is little in dispute.[33] -The most convincing of these lines of evidence are those which are -shown to be outside the range of any form of selection, as well as -the _distributional_ factors of Mendel and de Vries. It is well to -enumerate here the six different factors in organic evolution which -might claim a share in the production of such humble phenomena as form -the subject-matter of this volume--they are: - - 1. Personal Selection of Darwin. - 2. Sexual Selection. - 3. Histonal or Cellular Selection of Roux. - 4. Germinal Selection. - 5. Inheritance according to Mendelian principles. - 6. Inheritance of Mutations. - - [33] With the exception perhaps of the highest of all, for since the - publication of Prof. Woods Jones’ _Arboreal Man_ the question “Who is - Man?” has received a new answer. - -There is a somewhat severe and ill-defined condition attached to the -formula in question for it demands that such modifications as will -satisfy the neo-Darwinians shall not be _correlated with any useful -character_.[34] If such a _conditio sine quâ non_ were taken too -literally it would at once foreclose the case as to the possibility of -transmission of modifications at all, the questions of issue ought in -that case never to have been raised--and, _cadit quæstio_. This cannot -be the intention of the biologist who propounds the formula. It could -not reasonably be carried so far as to insist that a modification -arising from a certain habit, active or passive, in an animal, and -which on that account, and on paper, may loosely be said to be -‘correlated’ with it, is to be ruled out. That would be tantamount to -saying for example, that, because an animal must lie down in a certain -attitude when it rests, or walk or run in a certain manner, in other -words that it is useful to exist, certain modifications claimed to be -due to these fundamental parts of existence must be excluded from the -inquiry. The neo-Darwinian is not a critic easy to be entreated, but -_that_ he would not claim. Let me take one example of what I mean. A -short-haired dog will spend a considerable part of its daily life, -and presumably a long line of ancestors did so too, lying with its -forelegs planted in front of its chest and its head either raised in -the air when awake or resting on the upper surface of the forelegs (of -course the familiar attitude of a dog with its body and head curled -up and fore-legs doubled is not referred to here). If the hairy coat -be examined over its neck and jaw, which lie in this attitude, on and -against the forelegs, a remarkable reversal of the direction of the -hairs is found and the outline of this forms an accurate mould of -the surface applied to the forelegs. This is transmitted of course -from previous generations of domestic dogs. A precisely analogous -reversal of the hairs is found on the under or extensor surfaces of -the forelegs, matching with wonderful exactness the area of pressure -of these on the ground, and anyone can see it who has a canine friend -of the fox-terrier type. Long-haired dogs display it less neatly -outlined. An instance such as this cannot be excluded from the evidence -forthcoming because it is correlated with the useful “character” of -lying in a certain attitude. Such a phenomenon, many similar to which -will be seen later, had at any rate an origin _de novo_ at _some time_ -in the ancestral stock, and in _some way_. To discover these is part -of my business. The boldest neo-Darwinian will not claim that this -arrangement of a dog’s hair arose by selectional processes within the -germ either in the initial or completed stages. - - [34] My italics. - - -Correlation. - -The term “correlation” is somewhat scornfully said by Weismann to be -“unquestionably a fine word,” and it has indeed in biological writings -a very varied set of meanings. I will not vex the reader with a -reference to our old friend Mesopotamia, but mention what Dr. Vernon in -_Variation in Animals and Plants_ says of the term, referring to the -relation between stature and head-index in man: “Such a statement must -vary according to the notion of the observer as to what does and what -does not constitute correlation.”[35] The most approved and precise -meaning of the loose term in question is that associated with the work -of the biometricians, and a few examples from Dr. Vernon’s book will -show how far this conception of correlation is removed from the literal -application of Professor Thomson’s formula. Dr. Vernon treats of such -phenomena as the correlation of the long heads of greyhounds with -length of legs, contrasting them with the shortened heads and legs of -bull-dogs. He describes also the correlation in man between the stature -and length of forearm from elbow to tip of middle finger, correlated -measurements of crabs, of external structures of prawns, the tufts of -Polish fowls correlated with perforations in the skull, also certain -constitutional peculiarities with colour of skin. These few cases are -enough to give an idea of the more precise and fairer acceptation of -the term, but while these form a useful subject for minute study it may -be remarked that they agree also with Lamarckian factors as to their -origin and development. They are much more in line with Darwin’s use of -the word and are strangely reminiscent of the well-known example of the -Irish elk with its great head and horns which was brought forward in -favour of Lamarckism by Herbert Spencer. They breathe an atmosphere of -physiology rather than anatomy, or function than form. - - [35] p. 74. - -Enough has been said here by way of defining the terms of the issue. -The negative we have to sustain is that the following facts and -observations declare that certain small modifications cannot be -governed by selection and are not correlated with useful characters. -It will be shown later that Professor Thomson’s stringent condition -is not in all of them compiled with, but that, in spite of this, the -probability of their being valid examples of Lamarckism in practice is -immense. - - - - -CHAPTER IV. - -INITIAL VARIATIONS AND TOTAL EXPERIENCE. - - -The present chapter is on _a priori_ lines and will perhaps be -dismissed with a wave of the hand or hurriedly skimmed over, but I pray -the reader at least to read the two or three last pages of it. It is -at any rate suggestive, and perhaps I may anticipate the comments of -the neo-Darwinian and throw myself on his mercy by mentioning a remark -of the late Sir Andrew Clark, prince of physicians and genial cynic, -which he made to a patient in my presence. A lady not distinguished for -depth of thought asked him a rather silly question in medicine. As if -offended he drew himself up, holding in his hand a cup of tea which he -was enjoying, and replied at once “Madam, you must get a younger and -more inexperienced man than I am to answer you that question.” - -A very high degree of probability may be attached to the presupposition -that Lamarckian factors, even in their humblest form, may enter into -the story of the organisms as historical and living beings. Every -hypothesis in matters of science, or, to put it at its lowest, every -scientific guess must transcend the evidence at the time available. - - -Total Experience. - -The suggestion I venture to make here is that if we take a -comprehensive view of certain two great groups of phenomena in nature, -which may be termed universal in their extent, it is difficult to -conceive that they are not causally connected in the sense that one -is the universal antecedent of the other. On the one hand are found -universal minute differences, not only between any pair of organisms, -but of any two corresponding parts of any organism, even to the size -and shape of each leaf on each plant. On the other is universal -discontinuity of _total experience_ of all organisms. This term -includes all the stimuli of use and environment to which an organism -is exposed throughout its whole existence, and its response to them. -It includes the whole succession of active and passive stimuli which -begin with the formation of a zygote in higher forms, for example, and -continue till the death or end of reproductive life of the individual. -It stands for such stimuli as arise from _habitat_ on or in the -earth, in various levels of salt or fresh water, in sea, lake, pool -and river, and in the branches of trees, from _climate_, from degrees -of _light_, _temperature_, _moisture_ and _wind_, from presence and -activity of _enemies_ and _rivals_, from _supplies of food_, from -_geographical_ and _topographical_ position. Such an enumeration of -stimuli might be much extended if it would serve any purpose. But it is -enough to say that the number of such stimuli, and the varying degrees -in which these are received and responded to, have hardly any limit -which we can conceive. It is a very different and harder task to find -out the proportion in which such stimuli are advantageous, injurious -or indifferent to the organisms, but it may be taken as certain that -the vast majority are indifferent in the sense of producing structural -change, and, that the advantageous stimuli transmit structural effects -to offspring, is only a matter of very strong probability. If the above -two groups of phenomena are not causally connected they are intertwined -with remarkable closeness and perversity. This aspect of the “web of -life” has received attention, and deserves more. - - -Discontinuous Environments. - -Some reference must be made here to observations of Prof. Bateson in -his work on variation. In the first place he makes a most valuable -statement that “_the environment as the directing cause is essential -to Lamarck’s theory and as the limiting cause is essential to the -doctrine of Natural Selection_”[36] (which I venture to place in -italics on account of its importance to all who seek the pathway of -organic evolution) and points out also that “diversity of environment -is thus the measure of diversity of specific form. Here then we meet -the difficulty that diverse environments often shade into each other -insensibly and form a continuous series.”[37] This is clearly true -and important to the subjects he is discussing. But in regard to the -conception with which I am here concerned, that of _total experience_ -of organisms, it must be remembered that there is no such thing as an -environment apart from the living beings that it environs, and that -from this point of view there is no such thing in the world of nature -as a continuous environment. The environment of two amœbæ living under -a cover-glass is, for them, far from continuous. In their infinitesimal -existence the exact position they occupy in the environing drop of -fluid, in which the proportion of their humble fare at one side of the -cover-glass is not the same as that on the opposite side, renders -their environments discontinuous, or different from that of another -amœba occupying a position and “environment” which _we_ should consider -identical. And this consideration applies to the other few “tropisms” -which enter into their little lives. This statement may be difficult -to prove, but it is a necessity of thought. An illustration may assist -one in visualizing such discontinuity. A fly is seen crawling at its -own pace up one of the great pillars of St. Paul’s Cathedral. It comes -to one of the thin layers of cement worn down with age and so delicate -that a man can just see it in a good light. The fly pauses, and passes -into what is for it a chasm, with as much relative deliberation as the -man would show in passing across a deep railway cutting. The number of -pictures that could be made of cases corresponding to that of the amœba -is incalculable. A few will suffice. Two plants of the common nettle -are growing on the south side of a ditch in a lane, one rooted a foot -higher than the other. The upper one receives throughout its life from -wind and sun stimuli slightly different from those received by the -lower, and from the soil slightly less moisture. These again receive -stimuli very different from another pair on the northern side of the -lane. Again in windy weather a clump of sycamores facing the south-west -in England, and situated on the ridge of an eminence, will receive -very different stimuli from a similar clump on the north-eastern slope -of this eminence, and will demonstrate the fact, as to force of wind, -by a marked slope to the North East. Even in either of the clumps the -individual trees present varying degrees of slope according to their -position. The total experience of these two clumps of sycamores and -of any two in each clump is obviously different. In a windy situation -you can tell in July which is the prevailing wind by noting the main -inclination of the ears of corn in a field. Again two male sticklebacks -in a pond will make nests for the eggs, there to be deposited, and one -will choose a spot on the southern and another on the northern side of -a little promontory of soil and stones at the edge of the pond. One -will find ready for him materials for building his nest different from -those of his rival, and he and his wife and family will receive for -that season very different stimuli, and so will the stimuli differ in -other phases of their existence in a pond occupying a few square yards. -On a sandy bank in a garden facing south you may discover two little -caves ingeniously hidden by a small opening, and in each of them you -can see a toad. Though these are only a few feet apart one is more -widely open to sun and wind than the other and one deeper than the -other, and whatever the other activities of the two toads may be in -their little shelters, they receive stimuli different in strength and -number. On another bank in the same garden less exposed to view, and -altogether more sheltered from sun and wind and enemies, a robin has -built a well-hidden nest. If the six fledglings in the nest are watched -when the mother is absent they are seen to occupy very different -positions of comfort, pressure and warmth. When the mother-bird returns -from marketing she is hardly impartial in the amount of food she -puts into their open beaks. But the slight and perhaps unimportant -inequality of their experiences as fledglings is nothing to that which -follows when they fly abroad, and which continues to the end of their -lives, the life of a robin being somewhere about ten years long. The -differences of the _total experience_ of the six young robins is easy -to picture. Again, surely, the total experience of two fleas on the -body of one plague-rat must be for such small creatures of importance -to their welfare, according as their respective “pitches” are on the -abdomen, back or legs of the host. When the life-history of a human -being is told in full the discontinuity of his total experience needs -no proof. The proof is written large before our eyes. But, perhaps, one -example may be given. There are two very eminent living writers, whose -light has certainly for some years not been hidden under a bushel, Mr. -Chesterton and Mr. George Bernard Shaw. We may be said to know them -well. Leaving out of sight the Celtic strain claimed by one, and indeed -all inherited differences, we see two men of perhaps equal ability, -near of an age, both living in London, both living by their pen, both -in easy circumstances. When one considers for a moment the different -company these two men keep, their different and opposing outlook on -life, their different and opposing forms of diet for their minds and -bodies (I know which of the two diets of those men I would choose and -with which of them I would prefer to be cast on a desert island) one -can only say that the total experience of Mr. Chesterton differs from -that of Mr. Shaw as cheese from chalk, which things, incidentally, are -an allegory in the philosophy of life. - - [36] _Op. cit._ p. 6. - - [37] p. 5. - -The thought here briefly expressed falls well into line with Prof. -Bateson’s statement that the directing cause of the environment is -essential to the theory of Lamarck, and I do not hesitate to add to -it the assertion that _all environment_, in the wide sense of total -experience, _is discontinuous_. There are no such phenomena in total -experience as unit-characters of allied forms, small variations are the -rule. Without doubt a large proportion of the stimuli received by an -organism are as figures written on a slate and at once wiped off. They -are as the snows of yester year. The most they do is to contribute in -their measure to the metabolism of the organism, being too numerous -and minute to affect any structural change. In a higher form of life -none but those which are frequently repeated in the individual and in -succeeding generations can effect any structural response. - - -Mould and Sieve. - -It will be remembered that a single example was given of a short-haired -dog in which its common habit of lying was associated with a certain -pattern of hair. This introduces and illustrates the very wide -conception of a moulding process undergone by an organism. It is one -familiar to biologists and very much so to Professor Thomson in his -various writings. Not less is he an exponent of the metaphorical work -of the sieve of natural selection. I therefore claim nothing new when, -with the temerity of certain persons treading where others are said -to fear to do so, I invent an inclusive term and propose to call the -two fundamental factors of organic evolution _Plasto-diēthēsis_[38] -in which the conceptions of mould and sieve are included and -hyphenated. This word is no more proposed for its elegance than are -_panmixia_, _amphimixis_ and _tetraplasty_, though perhaps it may be -the etymological superior of one or more of these. It is at any rate -inclusive and perhaps sufficiently audacious to assure the inventor of -the title of Dr. Pangloss of controversial memory. But as hard words -break no bones I have taken this risk and it would appear to be a -convenient “conceptual counter” and even Professor Karl Pearson could -not consistently forbid it. It has at any rate the merit of having a -meaning clear to all friends and opponents alike of Lamarckism. It -will be observed that the two words are placed in what I take to be -their natural order as expressive of the Alpha and Omega of the story -of organic evolution. The moulding process is claimed to precede that -of the sieve, as physiology precedes anatomy and function structure, -in that form of biological speculation which is held here to be the -soundest.[39] - - [38] From the Greek. {Πλαστος from verb Πλαττειν to mould. - {διηθειν to strain through. - - [39] The twin metaphor here chosen for the name of a complex natural - process should be cleared a little of a certain obscurity of meaning. - A mould is familiar to all in domestic and industrial matters, but - there are two sides to the metaphorical conception. A plastic object - may be moulded by the hand of man as in his ruder, but more laborious - days, or it may be pressed into an artificial mould that he has - made by means of his hands and tools. One of these we know in the - rude pottery made by prehistoric man and the vessel of the potter - described by Jeremiah the prophet. We know also those machine-made - moulds, so accurate as to be fitted for the coinage of a nation and - able to puzzle a clever coiner who tries to copy them. We know the - rough hewing of the stone by the sculptor which follows his moulding - of the clay. And in Sacred Writ we read of a double process when the - Hebrews not content with their object of worship took the golden - ear-rings of their women and Aaron “received them at their hand and - fashioned it with a graving tool, after he had made it a _molten - calf_.” But as no conception of a mould in biological matters, which - connotes the rigid accuracy of the coiner’s mould, can represent the - truth, the rougher and freer meaning of the term is here employed. - A similar double meaning is implicit in the metaphor of the sieve, - considered as a human utensil. I believe we owe this idea of a sieve - to Professor Thomson, but am not sure on this point. But I have not - been able to find any definition as to the way in which the sieve of - natural selection is held to act. A sieve is of course for sifting - substances, and the size of the mesh is adapted by us for the purpose - we have in view. We may want a sieve to hold back for us the fit or - good and allow the unfit or bad to pass through, for example wheat - and chaff, or we may employ it to separate sand for our purposes from - fine gravel. The former is of course the most common of the purposes - for which a sieve is used. So here the comparison of personal - selection with the action of a sieve agrees with this aspect of a - sieve, the fit being retained and the unfit allowed to pass through, - thus agreeing with that view of Spencer’s of the survival of the - fittest which is held by most authorities to be more accurate than - Darwin’s Natural Selection. - -So the banns between Lamarck and Darwin are published, not for the -first time of asking, and who shall say that there is cause or just -impediment why these two should not be joined together in holy -matrimony? - -I conclude this chapter with a passage from the life of Columbus by -Washington Irving which affords a fitting parallel from history in the -higher development and union of two formerly hostile Kingdoms, and the -moral of it is clear and simple. But as a forensic junior I beg to -enter a _caveat_ to the effect that though the name of Columbus occurs -no suggestion is made of the discovery of a New World. - -“It has been well observed of Ferdinand and Isabella that they lived -together not like man and wife whose estates are in common, under the -orders of the husband, but like two monarchs strictly allied. They had -separate claims to sovereignty in virtue of their separate Kingdoms, -and held separate councils. Yet they were so happily united by common -views, common interests, and a great deference for each other, that -this double administration never prevented a unity of purpose and -action. All acts of sovereignty were executed in both their names; all -public writings subscribed with both their signatures; their likenesses -were stamped together on the public coin, and the royal seal displayed -the united arms of Castile and Aragon.” - - - - -CHAPTER V. - -METHOD OF PROOF. - - -In a matter of scientific inquiry one cannot go far wrong if one -follows the advice of Henri Poincaré, who lays down certain principles -of method; four of these are the following:-- - - (1) The most interesting facts are those which can be used several - times, those which have a chance of recurring. - - (2) The facts which have a chance of recurring are simple facts. - - (3) Method is the selection of facts, and accordingly our first care - must be to devise a method. - - (4) We should look for the cases in which the rule established stands - the best chance of being found fault with. - -The groups of facts described in the succeeding chapters are in -agreement with these principles in the main, and are perhaps like a -dust heap for their intrinsic value. But one knows that before now -among a good deal of _débris_ a rusty key has been found which has -opened a cabinet containing certain treasures, and in the hands of -someone else than the finder has produced useful results. - -The headings of the chapters describe the facts, and there is no -need to enumerate them here. The first and largest group is studied -according to a method which is in a measure applied to all the others. -Most of them are external or superficial phenomena and accordingly are -open to others beside the expert for observation and corroboration, or -the reverse. The typical plan adopted is as follows: a large number -of related phenomena are chosen, and the more prominent of these are -observed and described. Keeping in mind the two plain issues laid down, -the origin of initial modifications and their transmission, I have -selected the facts because, especially such as those of the hair, they -are very simple, of wide distribution in animals well known to us, -such as the domestic horse and man, and none are brought forward which -any other observer cannot study for himself if he has some anatomical -and physiological knowledge, some training and care in recording -observations. In most centres of population there are still left a good -supply of horses in streets and stables, of preserved specimens in -museums and living ones in zoological gardens, and of hairy young men -who will hardly refuse a polite request to examine the minute hairs -clothing their trunks and limbs. One has to pursue a certain amount -of that study which may be called the sister of plant-ecology, that -is, animal-ecology or the behaviour of animals at home. The student of -these matters, it may be freely admitted, will complain, unless he has -some hypothesis or line of thought to follow, that he has been set down -in a valley in which the bones are very many and very dry. But, armed -or primed with an hypothesis, he may find an affirmative answer to his -question “Can these bones live?” Every group of natural phenomena, -_without exception_, has some meaning for those who will interpret -nature rather than bully and slight her, and whatever anointed king -may claim sovereignty over it the humble fact cannot be denied that -“whatever phenomenon is, _is_.”[40] Again I would refer to Howes’ -inspiring note: “We live by ideas; we advance by a knowledge of the -facts; content to discover the meaning of phenomena, since the nature -of things will be for ever beyond our grasp.”[41] The facts adduced -are simple, have a chance of recurring and are widely distributed -among multicellular animals--the botanists and plants can very well -take care of themselves. I must once more state that I am attaching -to the considered facts a value of a somewhat unusual kind--_their -intrinsic unimportance_. For anyone who has had to encounter the -skilful dialectics and counter-attacks of a well-equipped neo-Darwinian -it is well that he should remember the maxim of Napoleon, “Be -vulnerable nowhere.” It is necessary to show evidence for Lamarckian -factors in which no degree of selective value, survival-value, can -be seen by hostile sharp-shooter while he works in his trench. The -main line of defence, or more correctly what Hindenburg would call -“offensive-defence,” is therefore made to rest on the phenomena of -hair-direction, which, I submit, are impregnable to the forces of -selection, probably in all the hairy mammals, but certainly in that -hairy animal called Man. - - [40] Jevons. - - [41] British Association of Science 1902. Zoological Section. - - -Thesis. - -If these groups of phenomena were being studied apart from the -hypothesis they support, a much more full treatment of all of them -would be required, such as I have given to those of hair-direction in -a book published in 1903 on _Direction of Hair in Animals and Man_. -The limited thesis, however, here upheld is that the phenomena are -produced by the factors of stimuli and response in the course of -the total experience of the organism, that the essence of the matter -is the production of initial modifications, that instances of these -in well-known animals are produced before our eyes by ascertainable -mechanical stimuli, and that, especially in those of hair-direction, -experiment is adduced in proof of the thesis that some modifications -are transmitted. - - -Procedure. - -The order of proceedings may be tabulated thus:-- - - (1) Observation of selected facts. - - (2) Evidence that certain of these are produced in the lifetime of - the individual. - - (3) Evidence that among the facts of direction of hair and others - there is to be seen an orderly evolution rather than a casual - appearance of the changes noted. - - (4) An hypothesis as to their production. - - (5) Exclusion of selection as a possible cause of these, and of - correlation as properly understood. - - (6) Experiment in verification of the Lamarckian interpretation of - the phenomena. - -And here, before I hear some Prince Henry of the genus Weismann, Mendel -or Gallio groan aloud: “This intolerable amount of sack,” I proceed to -offer him a few loaves of home-made bread. - - - - -CHAPTER VI. - -EVIDENCE FROM ARRANGEMENT OF HAIR. - - -_Ex Uno Disce Omnes._ - -The singular arrangement of hair on the forearm of man is the subject -of some curious statements by Darwin, Wallace and Romanes, and these -suggested to me twenty years ago the following line of thought. To many -minds the text will appear a humble one, but it opens many avenues of -inquiry. - -These three illustrious men are all more or less inaccurate and -incomplete in their descriptions of the hair on man’s forearm, though -Romanes[42] gives a drawing which supplements his written account. -They looked upon it as a vestige of the pattern of hair on the forearm -of existing anthropoid apes, especially the orang, in whom its -fully-developed form was an adaptation governed by Natural Selection. -Of the three, Wallace is the most uncompromising on behalf of this -view, Romanes rather accepts it _en passant_, and Darwin in a long -passage[43] adopts it with some reserve and his usual respect for the -work of his great co-worker, as the most probable explanation of a fact -which lay heavy on his scientific conscience. Indeed, for all these -great men it was a _crux_, though Romanes, with his Lamarckian views, -need not have found much difficulty with an alternative account of -it.[44] - - [42] _Darwin and after Darwin_, Vol. 1, p. 90. - - [43] _The Descent of Man_, Chap. VI., p, 151. - - [44] I may remark that Darwin seems at an earlier date to have made a - very curious suggestion in this connection, for Hartmann, in his work - on Anthropoid Apes, p. 99, quotes him as saying: “We should, however, - bear in mind that the attitude of an animal may perhaps be in part - determined by the direction of the hair; and not the direction of the - hair by the attitude,” a notion so obviously untenable that it does - not appear in the second edition of _The Descent of Man_, 1896. - -At the time when these statements were made, the lineal ancestors of -man were much more definite personages than they are now, as Arthur, -the legendary Celtic hero, was formerly held to be an historical -personage more than is the case now. These ancestors were generally -believed then to be found among the four existing anthropoid apes. -The picture of our ancestor among the apes, as given by Wallace, in -connection with this state of the hair on his forearm, represents -him as spending much of his time like the gorilla, who, according to -Livingstone, “sits in pelting rain with his hands over his head.” He -would no doubt find the thatch-like arrangement of the hair a tolerably -efficient umbrella, but one may doubt very much if so clever a denizen -of the tropics would fail to find under the great branches of trees, in -a tropical forest, a better covering and one more like the roofs of our -houses. But when we cannot find a roof to our heads we--and the orang -or gorilla--naturally employ a substitute, and not otherwise. Be that -as it may, it is doubtful if the thatch of his forearms would supply -him with that survival value on which the theory of Selection depends, -to say nothing of the fact that in its incipient stage the reversal of -the slope of hair, inherited from the lemur stock, would be trivial and -useless. - -But one must ask: “Did man’s Simian ancestor really loaf away so much -of his time in this dull manner? and was the running-off of rain so -frequent and imperative a need as to make him set to work to invent -this special adaptation?” - -After some millions of years have passed since his day we are not in a -position to go beyond speculations, and this one seems barely credible, -moreover, it is quite unnecessary, as certain following facts will show. - - -Steps of the Inquiry. - -Having expounded the text and its context, I would mention that in -1897 I came across these views of biologists as to the very strange -arrangement of hair on man’s forearm, and was struck with the -inadequacy of the theory of Darwin, Wallace and Romanes to account for -the state of things which every man can find, if he looks for it, on -his own forearm. I examined a large number of apes and monkeys so as to -test the theory, and the results were published in _Nature_, Vol. 55, -under the title “Certain vestigial characters in Man.” Suffice it to -say that from the evidence I brought forward one had to choose between -two heresies: either to deny the Simian ancestry of man or to affirm -the inheritance of some acquired characters; and I chose the latter. -The choice of “evils” or heresies which had to be made then will serve -as an introduction to all that follows. - -This article was followed by a paper at the Zoological Society of -London on “The Hair-Slope in certain Typical Mammals,” and after this -came a paper at the same Society, giving evidence and reason why -certain patterns of hair in some mammals should rank as specific -characters. Various other papers at the Anatomical Society of Great -Britain and Ireland were read and published and others at the -Zoological Society, in which different regions of the hairy coat of -man and lower mammals were dealt with. In 1903 the whole subject of -the Direction of Hair in Animals and Man was treated in a book freely -illustrated. - -I then followed the advice of Horace and left the subject alone for -nine years, during which time my further observations and reflections -served but to confirm, except in two or three unimportant details, the -results and conclusions in the book and papers of an earlier date. -The connection between the habits of an animal and the distribution -of its hairy coat were always cropping up, and I saw then and see now -no possible explanation of the connection than that the former is the -efficient cause of the latter. - - -How the Hair is Arranged on the Forearm. - -Returning now to the text, the remarkable arrangement of hair on man’s -forearm, attention may be directed to the accompanying figure of the -forearm of a lemur, an ape and man, in which the extensor or back view -of this limb-segment is shown, the heavy “war-arrows” being employed -to direct the attention of the reader to the main lines in which the -hair-streams flow. The front or flexor surfaces in the lemur and -ape are not shown because they are precisely like the corresponding -back surfaces, and the flexor surface in man is shown in the figure. -The figures are so much like diagrams that a very little detailed -description will suffice. For the examination of the hair on man’s -forearm the best subject is a dark-haired youth, and it is easily -traced, though in any hairy subject it can be shown up well by placing -the forearm in water for a minute and allowing the water to drain -off. The normal and congenital hair-slope on the forearm is then well -displayed. - -On the front surface of man’s forearm the hairs point away from the -elbow and divide in the middle of the surface into two streams, one -passing to the outer and the other to the inner border in a downward -gentle curve, and they join the streams of hair on the back surface. In -this pattern there is nothing very peculiar, for it is shared by many -monkeys. - -When the back surface is examined it is found to present an arrangement -of the hair which is _unique_ among hairy mammals. The figure shows the -eccentric course taken by the hair on the back surface. In the centre, -exactly along the extensor border of the ulna, from the wrist to the -point of the elbow, the hair-stream has been bold enough to turn -straight _upwards_ in a narrow line, and it was here that our three -great leaders saw their chance of claiming for Selection a tiny bit -of territory, a kind of Duchy of Luxembourg between two great States, -though, as I proceed to show, the claim is disallowed and untenable. - -[Illustration: Fig 1.--Arrangement of Hair on the Forearm.] - -In the ape the hairs of the forearm are much longer and thicker than -those of man, and both on the front and back all point _from the wrist -to the elbow_. - -In the lemur all the hairs point _from the elbow to the wrist_. - -In the products of Nature there are no freaks, or impish tricks -performed, and it is not for nothing she does her work. Every one of -them asks for and should receive an explanation consistent with fact -and reason, and here comes in the need for studying, as one may, the -broad outlines of man’s ancestry. His ancestor being now sought in an -earlier and more generalized stock than that of the four genera of -anthropoid apes known to us, the most instructive and safest line to -take is to trace him back to the stock lemur, who remains to-day among -the most Chinese or unchanging of known mammals. In his illuminating -work, _Prehistoric Man and History_, Professor Scott Elliott adopts an -excellent term, “lemur-monkey-man,” to sum up, without missing links, -the long ancestry of man. I take the liberty of adapting this term more -closely to the present inquiry and use that of _lemur-ape-man_ instead, -for whatever may be the relation of man to present apes some ape-like -ancestors enter into his genealogical tree.[45] For my purpose the -monkey is less useful because his hair-slope differs so little from -that of lemurs, whereas apes have made for themselves a very remarkable -position as regards the hair of their forearms. Our series of animals -for study is then well represented by the lemur-ape-man--hypothetical, -necessary and serviceable. Through all the immense stretch of time -occupied in this process of descent there has been ample opportunity -for the lemur to change his fashion to that of the ape, and the latter -to change to the present fashion of man. - - [45] This was written before the publication of Professor - Woods-Jones’ book _Arboreal Man_. - -This simple arrangement of the lemur’s hair is common to that of all -the more primitive long-bodied mammals, of which an otter is a good -example, and I venture, greatly daring, to call this the normal slope -of hair. Somewhere and somehow in the human tree there has appeared -a total reversal of the lemur-type; the stock of apes acquired a new -fashion, and gradually discarded altogether their ancient inheritance, -beginning their innovation perhaps, with _Dryopithecus fontani_ in the -Miocene Age. - - -The Dynamics of Hair-Pattern. - -There are a few well-known facts which it is necessary to bear in mind -if one is endeavouring to understand the mode of origin and order -of the events before us. The hairy coat of a mammal is composed of -individual hairs of varying length, colour and thickness, each being -rooted in a tiny pit in the skin and growing from a papilla at its -base. As the hair grows, its free end is pushed away from the papilla -at the rate of one inch in two months. This is the rate in man’s hair, -and it is probably greater in the case of lower mammals on account -of the greater importance and physiological activity of their hairy -coat than in man’s. But one inch in two months is a close enough -calculation. Here, then, is a structure which grows throughout the -whole life of the animal, and has to dispose itself somehow on the -surface of the skin. It does this _in the line of least resistance_, -and to trace this line is the Alpha and Omega of the present inquiry. - -There is a conception of much value in understanding the dynamics of -the distribution of hair, and that is to view the hair of mammals as -composed of certain streams. As in every illustration, this conception -may be challenged because of some difference the critic may find -between these streams and a stream of fluid. It certainly does not -leave its bed as do the component parts of a river, a glacier or molten -lava, for the base of the hair is fixed. But it will serve, and is -at least not more open to objection than certain useful metaphors in -biology as when the genealogy of man and animals is pictured as a tree, -or the living things of the earth as a “web of life.” It is, then, as -_streams moving at the rate of one inch in two months in the lines of -least resistance_ that I propose to discuss the animal hair and its -diverse patterns and offer no further apology for doing so. Just as -in the cases of a stream of water with varying banks and rocks in its -course, or a glacier with its mountain-sides and sinuous valleys, or a -stream of lava with small projecting surfaces of a mountain, our stream -of hair flows on, hindered only by adequate obstructions. - -Yet another conception from the region of metaphor must be mentioned. -It is one which will commend itself to every mind which has been -steeped in thoughts of warfare for five years. We are all soldiers now; -we think in terms of military affairs. In the case of our hair-streams -there are in many regions two forces directly opposed to one another, -others in which no struggle has yet occurred, as, in the Great War, -Italy was not at one period at open war with Germany. - -Between the opposing forces in our small battle-field of the hairy -coat there have been waged battles to which those of Mukden, Verdun, -the Somme and Arras, are not to be compared in point of time. They -are but as one day to a thousand years. On one side of the conflict -in our present chosen field the ancient primitive type of the lemur -has remained entrenched for some millions of years, until there arose -new forces in its descendants on the other side and this changed the -war of positions into one of movement. It was indeed “a contemptible -little army” which came forward to oppose the ancient barbarian -forces of the lemur, long prepared and organised, and these new -armies fought under the banner, Habit. In the slowly-formed patterns -in many types of mammals we have records of the treaties made after -these long struggles and the rectifications of frontier which became -necessary. The critic may call these “battles of kites and crows,” -and ask What war correspondents were allowed to describe them; but a -battle, whether great or small, long or short, is important to the -parties concerned, and it is open to us to “reconstruct” the facts of -the battle as do the historians on their part, for example, Sir James -Ramsay the battle of Agincourt--with tolerable verisimilitude. But in -science, especially geological science, the process of reconstruction -is much more ambitious and bold than any that is here attempted. Who -has not been fascinated, if he has read Sir E. Ray Lankester’s work -on Extinct Animals, by the skill and daring with which he conveys to -us a vivid idea of the form and mode of life, with scanty data, of -the extinct Moa of New Zealand, the great Pterodactyle, Pteranodon, -or the Diprotodon of Owen--“the probable appearance in life” of these -uncanny but very real inhabitants of the earth in days long past. How -skilfully did Owen from a piece of bone seven inches long, sent to -him by a gentleman in New Zealand sixty years ago, pronounce it to be -a part of the thigh-bone of a bird like an ostrich, and then after a -few years had passed, confirmed it by more bones of the skeleton, till -the large Moa, extinguished 600 or 700 years ago by the Maoris, lived -again before us--an historical personage; or how by the examination of -the skull and most of its skeleton the giant marsupial from Australia, -Diprotodon, was resuscitated and admired; or again, how from the bones -of the arms, shoulder-girdle and fingers was built up the strange body -of Pteranodon, the great flying dragon. All of which is the legitimate -and approved business of biologists and palæontologists, and this -digression is made here to show that my line of treatment of a little -subject agrees with that in a greater one; nay, it even proceeds in -its explanations of events on the ever valuable principle of Lyell in -a still greater one without which to-day geology would be a thing of -naught, that is, the principle of _explaining changes in the surface of -the earth by reference to causes now in action_. The objection that one -subject is very great and the other very small is not valid; for one as -much as the other there are millions of years to be had for the asking. -Who in these days hesitates to talk and try to think in millions?--tens -of millions of men, millions of soldiers, millions upon millions of -money, millions of bacteria in vaccines and millions of money belonging -to other people disposed of by the new spendthrift Minister? - - -From Lemur to Ape. - -Returning now to our Eocene lemur we must remind ourselves of the -problem before his simple mind and those of his Simian descendants. How -was he to change so greatly the direction of the hair on his forearm -(Fig. 1) till it should turn right about face and imitate those great -German “victories” of Hindenburg, well called Marshal Rückwarts? The -problem lies open in the Figure and receiving no aid from Selection or -survival of the fittest, in this little effort, he had to fall back on -the eternal and tedious force of habit and use. I am afraid if here I -were interrupted by some critic, more learned than wise, by a summary -demand on the part of Selection for its share in the result, I should -be tempted to reply with the word Φλυαρια employed by George Borrow, -forbearing to give the translation of the reply as he gives it. Anyhow, -it is a case in which to “listen politely and change the subject.” - -Here comes in the aspect of strife between primitive and new -obstructing forces in a little hair-stream. The lemur lives in trees -and carries on a stealthy nocturnal business, moving on all fours in -quest of his daily bread, and no external force or new habit avails to -modify the hair-slope on his forearms, and so it remains until some -primitive form of monkey, gradually evolving into a primitive ape, -brings into the family new habits and customs. Other men and other -manners appear in the Miocene Age. Our supposed Dryopithecus fontani -becomes more upright in his bodily, and perhaps his moral habits, -and spends an increasing amount of his leisure time in the sitting -posture; his hands are frequently grasping a bough as he sits and -reflects, it may be in a man-ward direction, or, as is more likely, on -his last meal of nuts and fruits. But he did not spend quite so much -time as Wallace and others think in this futile attitude, for he knew -in his way as much as the modern bachelor does, of making his posture -comfortable and restful when he was not out at work, and he varied -his plans by resting his forearms on his thigh, crouched up and cosy, -and doubtless slept much in this attitude. All these bold departures -from his lemur-ancestor’s habits had the necessary result of altering -the slope of his hair on the forearms, which was now growing as long -and coarse as we see it to-day in the orang. In course of milleniums -the ancient forces yielded to those of the new armies, and the once -normal slope became reversed in a way which shocked the conservative -lemurs of his day. It requires little imagination to see how the -lengthening thickening hairs on this limb-segment became changed in -their direction by friction against the opposing surfaces of the -thighs, by gravitation, and the frequent dripping of rain when they -were held up to grasp a bough. Here then we see at work new forces of -friction, pressure, gravitation and dripping of rain, turning endlessly -and slowly the lemur-fashion into the ape-fashion, with unlimited time -for their effectual action. In this stock of Man’s ancestry Selection -was taking care of the individual and Habit of the details of his -making--two truly harmonious partners. - - -From Ape to Man. - -Another step, and a long one, has still to be taken from the -ape-fashion to that of man. Bearing in mind that the lemur-fashion has -been totally reversed by the ape it startles one to find that man in -his modern fashion has largely reverted to that of the lemur on the -front and sides of his forearm. This is clearly shown in Figure 1. -There also you see graphically recorded in the hair of the extensor -border of the ulna, a little _backward_ streak, a poor little legacy of -fifty pounds from the fortunes of many thousands once possessed by the -ape. From the present limited point of view, man is a veritable pauper, -and his possessions in this limb-segment may with some irony well be -called a “vestige.” - -Professor Scott-Elliott in his book, _Prehistoric Man and His Story_, -p. 60, goes rather wide of the mark here in his graphic picture of our -rude ancestor and his hard life. He gives too strongly the idea of -him sitting asleep in raging gales, in driving rain which is neatly -conducted by the thatch of his hair off his skin. As far as it goes -this need not be questioned, as a matter of probability, but he states -far too broadly “The hair on the arm, even of those civilised men who -retain sufficient to trace the arrangement, turns down both upper -and forearm to the elbow”[46]--true as to the upper arm, but only -true of the forearm in a very narrow streak of hair over the extensor -surface of the ulna. The fact is that in every human being, not too -old, its course can be traced with a lens. He overlooks also from -this protective point of view the fact that the ape or early man, in -the position of rest he describes, would have very much the reverse -of protection from the “lie” of the hair on his thighs, for this is -towards the knee and is well calculated to catch the rain and conduct -it carefully, or let it run, into his groins. So the protection theory -(under the empire of Selection) is again in straits. But I must not -forget my self-denying ordinance alluded to in the Preface, but will -show how the ape fashion began to be modified into its present and -probably final form in man. Still further changes in the simple habits -of the earliest men became frequent, and fresh forces were organised in -our mimic battlefield. Gravitation gradually ceased to act as the hairs -became thinner and shorter. Friction and pressure changed their lines -of incidence with the increasing tendency of man to assume the upright -posture, for the surfaces exposed to pressure and friction were only -affected when the extensor surface or back of the forearm rested on -some supporting object, an attitude extremely common in man as we know -him now. Then came the opportunity of the primitive barbarian host, the -lemur fashion, by a prolonged counter-attack to recover on the greater -part of the forearm the ground lost millions of years before by the -ape, and then was engraved on the forearm of man the permanent treaty -which we have before us to-day. - - [46] _Prehistoric Man and His Story_, p. 60 - -This small and apparently trivial battle-ground has been described at -what may seem undue length, but it is a miniature of the rise and fall -of little empires such as here engage our attention, and I make no -apology for this to the reader who has gone thus far with me, for, on -the principle of _ex uno disce omnes_, all that follows in other areas -of the hairy coat of mammals will be the clearer, and little repetition -will be needed. - - NOTE.--Two terms have been used somewhat freely in this Introduction, - “vestige” and “normal,” and a few remarks upon them are not out of - place, for they are both somewhat ambiguous and apt to be carelessly - employed. - - A vestige in biological writings is almost the exclusive property - of the Pan-Selectionists, and no one can doubt that on the one - hand it is a far more correct term than that of rudiment which - Darwin employed so freely, on the other that they have a perfectly - legitimate claim to it in a large number of obsolete structures of - animal forms. But vestiges, footsteps, footprints, have another and - equally correct meaning, even if less often thus employed, in the - fact that a vestige or footprint may just as well be a relic of - what the race and individuals have _done_, as a relic of what they - have _retained_ in the way of possession, and I submit that the - facts and arguments I have here advanced afford a valid claim to the - term “vestige” in the results of certain _doings_ on the part of - animals--as will appear later still more clearly. - - The term “normal” is a fine field for dialectics, but neither - ordinary men nor scientific students can do their work without - its use, and yet it would have been an intellectual treat to - have heard how Huxley, for example, would have turned inside out - any opponent who chose to employ it to his dissatisfaction. In a - strictly-conducted tournament no evolutionary biologist would allow - its use--to his adversary. A norm for him exists only as one of - Professor Karl Pearson’s “conceptual counters,” a piece of mental - shorthand or hardly more than a _pis aller_. Among the fundamental - conceptions of organic evolution there is one which is almost a - truism, the doctrine of Heraclitus, πἁντα ρε̑ι, the everlasting flux - and change of Nature and her products. In strict logic, according - to what we all now believe, there is no possible norm. All that one - may do is to take stock at a certain epoch of evolution and label, - for our own convenience, some group, or organism or structure as - “normal”--and go on with our business, collecting some specimens, - calling them type-specimens, and putting them in books or cases in - the Natural History Museum--and then proceed to business. - - The biological teacher in his class room says he must live, he must - have his tools for his work, to which the idle student replies under - his breath, “I do not see the necessity,” but then few students - are now idle, and this jibe does not sting any one! The examiner - must have his normal human anatomy, and would ruthlessly plough - any daring examinee who tried to sophisticate the meaning of the - term “normal.” I have often been struck with what I must call the - intellectual audacity of a most eminent leader in physical science - and mathematics, who is not unlike a certain great Church, which - grants nothing to her adversaries but is not averse from taking. In - his _Grammar of Science_, written with a pen dipped in hydrochloric - acid, Professor Karl Pearson four times over, and perhaps more, - has the courage to call the human brain in this twentieth century - “normal.” Has he never heard of the coming Superman of Mr. Bernard - Shaw and other prophets? Thinking _sub specie aeternitatis_ has he - here in the West, and at a certain small epoch of time, any right - to call the human brain “normal”? I can only long that there may be - more normal brains such as Professor Karl Pearson’s, and am almost - inclined to echo the prayer of Moses, “Would God all the Lord’s - people were [such] prophets”! These comments on the term “normal” - imply no complaint against its use, indeed are a claim for it, and I - deprecate very much that form of criticism known in boys’ schools, - domestic circles, and among politicians as the _tu quoque_ reply, - and I hope the few ambiguous terms used in this book will pass the - censor, and help the reader. - - - - -CHAPTER VII. - -THE EVOLUTION OF PATTERNS OF HAIR. - - -Some attention must here be given to the supposed mode of formation of -individual patterns of hair, that is to say, their evolution. So here -one has to move among the fields of hypothesis, without which detached -facts of nature are useless to science. - -The simplest pattern consists of a reversed area of hair appearing -between two adjoining streams; the more complex are whorls, featherings -and crests. No detailed description nor illustration of the former -are required, but I have prepared a diagram to illustrate the latter -(see p. 51.) (A) shows a whorl by itself; (B) a whorl, feathering and -crest. The arrows at the sides indicate the direction of the adjoining -hair-streams, the arrow in the centre of (B) the direction of the -reversed flow of hair. - -An understanding of the dynamics of a hair-whorl leads quite simply -to that of a feathering and crest, for the two latter are only the -results of the further extension of the battle of forces concerned -in the whorl itself, and the end of their conflict. A whorl marks a -point in the stream of hair where two contending forces have come -into collision; on the one hand the centrifugal force of growth from -each hair-papilla, the rate of which has been described, and on the -other a certain centripetal dynamic force which may be either that -of localised _friction_, _pressure_, _gravitation_, or _muscular -traction_, directly opposing or divergent. Thus conceived a whorl may -be looked at symbolically as a written treaty between two nations, -one of which has defeated the other, and actually as a proof that the -contending centrifugal and centripetal forces are in the state called -the balance of power. But when the centripetal force of some habitual -action prevails over that of the original force of growth in the -hair, a whorl becomes extended into a feathering, and the length of -this, metaphorically speaking, corresponds with the duration of open -fighting, and terminated by a sharp crest when another and a decisive -battle has been fought. A crest may again be looked upon as a “treaty.” -The whole process pictured here shows a battle followed by a treaty or -truce (W) again a retreat (F) and a counter-attack (C) with a final -treaty and peace. - -This hypothetical treatment, with addition of some metaphors, does not -carry us far enough to leave it thus to the tender mercy of that class -of critic who relies too much on the “argument from ignorance.” He -tells us such a process as I have pictured may be true or not, and that -no one can do more than leave the case open, and treat it like that of -Jarndyce & Jarndyce where it would remain in Chancery till all of us -concerned in the inquiry have returned to our dust. The critic might -reasonably ask for experiments which will bear out the suggested views. -But verification by calculated experiments is impossible, for, _ex -hypothesi_, the variations or patterns which are described require long -periods of time for their production. Such experiments being ruled out, -the evidence in favour of the hypothesis must be sought in some region -of the hairy coat of mammals where whorls, featherings and crests can -be observed in all stages of their formation. - -[Illustration: Fig. 2.--A. Diagram of a whorl. B. Diagram of a whorl (W) -a feathering (F) a crest (C).] - - -The Side of the Horse’s Neck. - -The field chosen for observation is, from one point of view, the most -remarkable among all the numerous regions in the great series of -hair-clad mammals. The side of the neck in the domestic horse displays -all degrees and forms of whorls, featherings and crests in such variety -as to be almost bewildering. I must have examined many thousands of -specimens of this valuable large mammal in reference to this state -of things on the side of its neck, and can only regret that I have -not kept any record of them as to number or quality, and I fear the -opportunity for doing so will not return in this country. There are -three reasons for this choice of field. In the _first_ place there is -or was an extensive supply of the specimens for examination; in the -_second_, the side of a horse’s neck is a region where no extraneous -or artificial agents, such as harness, except a bridle, can operate, -and therefore Nature and the animal’s habits have free play; in the -_third_ the neck of a horse in its locomotive life is subject to -powerful mechanical forces which are _constant_, literally speaking, -while it walks, trots, canters or gallops. Here then, if anywhere, one -may read the records, in indelible characters of hair patterns, the -history of its active life and that of its ancestors, and here also one -may reasonably expect to find these patterns in every possible stage -of formation, from a mere rudiment to the most finished product in a -whorl, feathering and crest--_and this is precisely what is found to -exist_. - -Even an observer not acquainted with the anatomy of this region who -watches closely a horse in action cannot fail to notice how at every -step taken there is a marked jolt of the neck produced in the neck by -the impact of its hoofs with the ground and in supporting its heavy -skull. I have computed several times the number of jolts that the neck -of a trotting horse sustains, in my numerous rides behind various -horses, during many hundreds of miles, and have reckoned the number -which occur in a horse trotting for an hour, at the usual rate at which -a doctor travels. This is on the average 6,000, and of course the -numbers of jolts in walking, cantering, and galloping vary according to -these different paces. But a great deal more of movement of the head -and neck is observed beside the jolt at every step. See how the animal -tosses up its head, twists it to this and that side for the mere _joie -de vivre_ when it is fresh, or, even when hindered by blinkers,[47] how -he turns his head to look at every passing object in the road with his -ancestral caution, how he will pass contemptuously a great horse-waggon -or even now a villainous-looking motor lorry, but will peer at a beggar -woman sitting beside the road, or a heap of stones, or a yapping cur! -All this vivid muscular work of a horse’s head and neck hardly ceases -while he is in action and at any rate not till he is dead beat, and -the higher the courage and breeding of the horse the more frequent and -brisk are his movements. Is it possible to conceive a region of the -body of any large mammal where more numerous, varied, and powerful -action of underlying muscles can be found playing their ceaseless -tricks on the sober normal slope of hair in the skin which covers them? -If there be any region approaching this I have not found it. - - [47] Blinkers ought long ago to have gone the way of bearing-reins - for draught horses. If a riding horse does not need them, no more - need a draught horse be thus insulted, for very little intelligence - and patience on the part of their drivers would have educated their - excellent brains into indifference towards startling objects. - -[Illustration: Fig. 3.--Superficial muscles concerned in the movements -of the head and neck of the horse.] - -[Illustration: Fig. 4.--Deeper layer of the muscles concerned in the -movements of the head and neck of the horse; the scapula removed.] - -The main facts of the anatomy of the horse’s neck must be referred -to here, so that a better picture may be obtained as to the powerful -forces which are found in conflict during the locomotive life of the -animal. Fig. 3 shows the superficial layer of muscles concerned in -the actions of its head and neck, and the manner in which adjoining -muscles diverge from one another should be noted. Fig. 4 gives the -deepest layer of neck-muscles, the shoulder-blade having been removed, -and Fig. 5 the immensely strong _ligamentum nuchae_, of yellow -elastic tissue, which extends from the base of the skull to the great -projecting spinous process of the lowest cervical and second and third -dorsal vertebræ. - -[Illustration: Fig. 5.--Ligaments and tendons supporting the head and -neck of the horse.] - -There are here indeed great forces for conflict--_first_ a layer of -strong superficial muscles, _second_ a layer of smaller muscles which -has not been figured, _third_ a deep layer of muscles, and _fourth_ a -powerful, widely-spread and strongly-attached mass of dense elastic -tissue, adapted for supporting the head without muscular exertion, but -by its elasticity allowing a downward jerk of the head and neck at -every step. It is an exceedingly important structure for a domestic -horse. - - -The Normal Arrangement of Hair. - -So much for the active part played by a horse’s neck and head, and for -the simpler anatomical facts of the region involved. Before proceeding -to describe the results of these as seen in the hair, it is well to -make sure of a point which a critic might raise. “How do you know,” -says he, “that some of the variations in this highly variable region -of the hair are not normal. What is the normal type here?” A very easy -answer to this is found by studying, not only any Ungulate known, -except the Gnu, but more particularly all wild Equidæ; and this reveals -the fact that in all this series the normal slope of hair prevails -here, that is to say, an even trend from head to shoulder. Variations -in others, indeed, hardly exist, and I may add that the absence of -variations here is a strong piece of negative evidence in my favour, -for no Ungulate comes near the domestic horse for amount and activity -of locomotion, which is indeed his _raison d’être_. He is the only -one that has invented new patterns. But a little direct evidence -can be brought which clinches this argument from inference based on -ancestry. I made an examination, at the stables of Messrs. Tilling, -at Peckham, of 100 consecutive specimens of hackney, for the purpose -of ascertaining the proportion in that group of those that showed the -normal slope on the neck to those with variations. In 62 of these the -normal existed on both sides of the neck, 18 Normal on one side, and in -the remaining 20 there were variations on both sides. If 100 specimens -of horses contain 80 with one side and 62 with both normal the previous -inference requires no further support. - - -Fourteen Varieties. - -I have put together here, and described, fourteen out of a much larger -number of the most instructive varieties of pattern that I have been -able to collect during the course of many years and examination of -several thousand horses. They comprise examples the mostly likely, as -I think, to convey to the reader an adequate picture of the results of -the strength, number and variety of mechanical forces in our present -battle-field of hair. The diagrams almost speak for themselves, but a -short written description will help to emphasise the salient points. - -[Illustration: Fig. 6.--Side of Neck of Horse. - -Normal type, hair-stream passing evenly in line of neck.--Bay hackney, -examined 3rd May, 1904.] - -[Illustration: Fig. 7.--Side of Neck of Horse. - -Complete whorl with wide feathering which extends from base of the neck -to the ear where it ends in a crest.--W.F.C. - -Brown hackney, examined 12th January, 1904.] - -[Illustration: Fig. 8.--Side of Neck of Horse. - -Offside, anterior portion of neck showing line of division, B to A, -along upper border of sterno-mastoid muscle, normal arrangement from A -to C. - -Grey pony, examined 15th December, 1903.] - -[Illustration: Fig 9.--Side of Neck in Horse. - -Near side, winter coat, showing normal arrangement from B to A, where a -division begins and extends along upper border of sterno-mastoid muscle -to base of neck. - -Brown hackney, examined 28th December, 1903.] - -[Illustration: Fig. 10.--Side of Neck of Horse. - -Line of division of streams curving upwards to the mane near the base -of the neck. - -Chestnut cart horse, examined 9th December, 1903.] - -[Illustration: Fig. 11.--Side of Neck of Horse. - -Near side, line of division along the upper border of sterno-mastoid -muscle diverted at C towards the mane. - -Bay cart horse, examined 11th December, 1903.] - -[Illustration: Fig. 12.--Side of Neck of Horse. - -Near side, at C upward curve towards mane. - -Brownish-yellow hackney, examined 18th August, 1903. - -The same horse as appears in Fig. 13.] - -[Illustration: Fig. 13.--Side of Neck of Horse--same specimen as in -Fig. 12. - -Offside, fully developed whorl, feathering and crest W, F, C, lying -along upper border of sterno-mastoid muscle. Two stages of formation of -this form of pattern in one specimen. - -Brownish-yellow hackney, examined 18th August, 1903.] - -[Illustration: Fig. 14.--Side of Neck of Horse. - -Near side, whorl (W) in place of common line of division, with wide -forward feathering to A, where the hair streams diverge sharply. - -Brown hackney, examined 19th November, 1903.] - -[Illustration: Fig. 15.--Side of Neck of Horse. - -Near side, showing (B to C^1) diversion of hair stream towards mane -(W^1F^1C^1) whorl, feathering and crest; W^1 to W^2 stream in normal -direction W^2 a second whorl. - -Chestnut cart horse, examined 1st January, 1904.] - -[Illustration: Fig. 16.--Side of Neck of Horse. - -Near side (W^1F^1C^1) showing whorl, feathering and crest along upper -line of division (W^2F^2C^2) a second fully-formed whorl, feathering -and crest, crossing both upper and lower lines of division, and -ending at W^1. Grey pony, examined 23rd May, 1903.] - -[Illustration: Fig. 17.--Side of Neck of Horse. - -Near side (W^1F^1C^1) whorl, feathering and crest, fully-formed, -cutting upper line of division at obtuse angle and a second whorl, -feathering and crest (W^2F^2C^2) along anterior part of common line -of division. Roan hackney, examined 7th November, 1903.] - -[Illustration: Fig. 18.--Side of Neck of Horse. - -Off side, simple whorl, behind ear at edge of mane.] - -[Illustration: Fig. 19.--Side of Neck of Horse. - -Simple whorl (W) at edge of mane midway between ears and base of neck.] - -There are pictured here the normal type, divergent hair-streams -partially reversed, simple whorls in different regions, a whorl and -feathering, whorls, featherings and crests, and these in several areas. -It is a veritable portrait gallery in which is portrayed the earliest -and latest stages of this family of fashions in hair on the horse’s -neck. They are grouped mostly in pairs. - -Fig. 6 shows the normal slope and by its side Fig. 7 gives a view of -the best specimen of a completed whorl, feathering and crest I have -been able to examine, _the whole length of the neck being occupied by -it_. So in this pair the normal and most extensive departure from it -lie side by side. - -Fig. 8 shows the way in which two streams of hair close up to the ears -begin to diverge. Fig. 9 a similar divergence towards the base of the -neck. - -Fig. 10 gives not only a divergence, but a well-marked turn in the -upper hair-stream and Fig. 11 the way in which this divergent turn of -hair is being converted into a feathering. - -Fig. 12 presents a stream of hair still more twisted from its course -than that of Fig. 10, and Fig. 13 a whorl going on to a feathering -which loses itself, without coming to an abrupt stop in a crest which -is the more usual course. - -Fig. 14 is a common type of whorl, feathering and crest in the most -usual situation. Fig. 15 a rarer and more complicated instance of a -simple whorl, a gap and then a whorl, feathering and crest in the same -“critical area.” - -Fig. 16 and Fig. 17 are rare cases of irregularly placed double whorls, -featherings and crests, and give evidence of unusually complicated -traction of adjoining muscles underneath this battle-field of hair. - -Figs. 18 and 19 show a simple whorl, situated at the very edge of the -mane, a very “critical” area because this looser and heavy part of the -neck is very much subject to jolting during the horse’s action. - -I have little to add to the graphic evidence afforded by these -pictures, each of which I observed noted and sketched as the bearers -of them came before me during many years of a “Captain-Cuttle-like” -disposal of some of my leisure. No clearer proof can be desired of -the view here advanced, that habit or habitual muscular action, and -jolting, is the cause of the varied patterns in this field, and that -according to the Law of Parcimony no other is required, this canon -of Occam being expressed more succinctly--_Neither more, nor more -onerous causes are to be assumed than are necessary to account for the -phenomena_. - - - - -CHAPTER VIII. - -CAN MUSCULAR ACTION CHANGE THE DIRECTION OF HAIR IN THE INDIVIDUAL? - - -It might seem unnecessary to most persons who are good enough to follow -this inquiry that the question asked above should receive an explicit -answer. We all know, of course, how a man’s hair is said to stand on -end in excessive states of horror or rage, and how a short-haired -terrier’s back bristles at the sight of certain foes. But it is not so -simple a matter to show that the direction of the hair is permanently -changed. I submit that the persons I mention are right in their opinion -for this work contains evidence throughout that muscular action beneath -the skin is the efficient cause in many regions of the formation of -hair patterns. But like Kirkpatrick when Bruce struck down the Red -Comyn we had best “make sicker,” and give as much evidence of the -affirmative question as any critic can demand. - - -Hairs of Human Eyebrows. - -As in the previous chapter I chose an open and plain field for the -evidence bearing on the formation of whorls and the like, so here I -turn to one still more clear for him who runs to read. In these days -old men are of less account than in earlier and simpler times, but I -claim to have found “a new use for old men” as I had almost thought -of calling this chapter. In this somewhat neglected group we have an -almost unlimited number of specimens for examination, and in their -eyebrows they furnish a valuable field for tracing some striking -results of underlying muscular traction. - -Darwin made one of his few mistakes when he included among rudimentary -and inherited structures[48] those few long hairs which are often seen -in the eyebrows of man, looking upon them as representatives of those -found in some species of macacus and the chimpanzee. That great and -modest man was, I am sure, not in the habit of making much use of the -looking-glass--not more than women who, as we know, rarely do such -a thing. But if he did he would have observed in his own splendid -frontal region and brows excellent examples of the phenomena which form -the subject of this chapter. This I know, though I never saw him in -the flesh, for it so happens that in the great volume published in the -jubilee of The Origin, and called _Darwin and Modern Science_, two good -photographs of him, at the ages of thirty-five and about seventy-one -are reproduced. These both show, but the later one much more clearly, -good examples of these long and not very ornamental aberrant hairs. -Thirty-five years of arduous thought and work had told their tale on -him and twisted from their normal paths the lengthening thickening -hairs of his eyebrows. - - [48] _Descent of Man_, p. 19. - -Also, if he had looked a little beyond the eyebrows he would have seen -some very deep wrinkles of the skin on his forehead and round his -orbits. It is these two groups of facts, wrinkles and twisted, changed -hairs of man’s eyebrows, which give the answer to the question “Can -muscular action change the direction of hair in the individual?” - -In 1903 I drew the attention of the Anatomical Society of Great Britain -and Ireland to these two groups of facts under the title “Notes on -the Eyebrows of Man,” and presented some large drawings of individual -elderly men of my acquaintance, and the present chapter is only an -extension of that little piece of work. - -No area of the mammalian skin is so useful and easy to follow as this -in answering the present question, for though the previous chapter -supplied part of the answer in a very fruitful field, the proof still -remained one of “tremendous probability” and not more. But in the -frontal and superciliary region of man there is complete proof of the -truth of the affirmative answer, as I shall show. - -Here again we must encounter our old friend the normal slope of hair. -As I stated in 1903, “The normal arrangement of the hair on the -eyebrows of a moderately hairy subject is as follows: in the middle -line the hairs of the two sides tend to meet and form a somewhat -confused group of hairs; passing away from the middle line the hairs -assume a nearly sagittal direction, then become more sloped away, and -a sharp change in the direction of the _frontal_ and _orbital_ streams -brings the remaining hairs into that regular accurate arrangement of -a united stream so characteristic of a hairy subject, and this passes -along the superciliary ridge to the external angular process”--all of -which can be seen at a glance by any one who looks closely enough, as -with the eyes of a lover, for example, at the brows of a dark-haired -maid or youth. In the young these hairs lie close to the skin, and with -that very interesting group of persons we have no more to do here, -except for one piece of practical advice to them which they will find -at the end of the present chapter. - - -Evidence from Artists. - -More than one kind of evidence may be brought forward in this case, -and I propose to “put in” a certain class of witness that not the most -acute cross-examining counsel, Daniel O’Connell, Hawkins, or even -Sergeant Buzfuz, can shake. I pity that young man or woman to-day who -has not mended several holes in his education by reading the books of -Dickens and Lever in editions illustrated by the immortal Phiz. If I do -no more for him by this passage than induce him to mend such holes I -shall have been of some use to his mind. For my part I look upon Phiz -as far superior to Hogarth or Cruikshank in the fidelity to nature of -his drawings of the faces of his numerous characters, especially the -old men. Look through _Dombey & Son_, _Bleak House_, _Pickwick Papers_, -_Barnaby Rudge_, _Tom Burke_, _Jack Hinton_, _Harry Lorrequer_, _The -O’Donohue_, and, perhaps best of all for the illustrations, _The -Knight of Gwynne_. Examine, with a lens if necessary, the delicate way -in which Phiz shows the projecting hairs on the eyebrows of his many -elderly men, and note at the same time the truth to scientific fact -which he shows in his _female_ characters, for only in the drawings -of “Mrs. Gamp proposes a toast” and of Mrs. Pipchin in “Paul and -Mrs. Pipchin,” and one or two doubtful instances, can I find that he -represents even his elderly women with this feature of their eyebrow -hairs. But see Captain Cuttle and Mr. Bunsby in “Solemn references to -Mrs. Bunsby,” both with strongly-marked shelves of hair sticking out -from the brows, Captain Cuttle in “The shadow in the little parlour,” -one of the fat coachmen in “Mr. Weller and his friends drinking to -Mr. Pell”--the sharp brush projecting from the brow of Bagnet in “Mr. -Smallweed breaks the pipe of peace,” that of Vholes in “Attorney and -Client, fortitude and impatience”--(the equally remarkable absence of -this feature in Pecksniff, Chadband and Skimpole, men without character -or feeling)--Gashford in “Lord George Gordon,” the fat figure in “The -Gallant Vintner,” Pioche in “Minette in attendance on Pioche,” the -courtier in “Louis XIV. and de Genchy,” “The death of Shaun,” the blind -man in “Joe the mighty hunter,” the right hand figure in “Mr. O’Leary -creating a sensation,” Sir Archibald Mc’Nab in “A fireside group,” -“Roade’s return to O’Donoughue Castle,” Sandy Mc’Grane and Old Hickman -in “Sandy expedites the doctor,” Daly in “Daly bestows a helmet on -Bully Dodd,” the knight in “The Knight is taken Prisoner.” - -Another witness to the scientific facts of the frequent presence of -these hairs on the eyebrows of elderly men, and the rarity of them in -those of women, is the dear friend of our youth, our friend even to -hoar hairs, the _Book of Nonsense_, by Edward Lear. Here in 110 vivid -drawings of several hundred characters, each of them sketched with a -few bold strokes, is inscribed again and again this peculiar feature. -Look at the “Old man with a nose,” the “Old Man of th’Abruzzi,” the -“Old man of Melrose,” the “Old man of Calcutta,” the “Old Person of -Anerley,” the “Old Person of Chester,” all with strange and striking -bushes of long hairs standing out from their brows. Again see how -hardly one of the female characters shows a trace of it even in -that most truculent “Grandmother of the Young Person of Smyrna” who -threatened to burn her, though her vertical wrinkles are formidable, -or in the remarkable face of the wife of the “Old Man of Peru.” The -“Old Lady of Prague” shows it in a moderate degree. Support of this -kind may be trivial, and so will the opposing counsel say is that of a -burglar’s finger-prints, but, _quâ_ evidence, it is as strong as that -which commits the criminal to a prison on this modern proof. No one can -suppose that Phiz and Lear fifty or sixty years ago had a prophetic and -treacherous insight into the harmless labours of a man in the year 1920 -who would exploit their labours to the advantage of his hypothesis, -and that they faked their caricatures for such a purpose. This is the -only alternative line for Sergeant Buzfuz to take unless he acknowledge -the facts to be facts, and betake himself to abuse of the plaintiff’s -attorney. - - -Eyebrows Interpreted by Wrinkles. - -When one comes to the interpretation of the curious shapes taken by -these hairs one is not left to inference, for Nature has put some -indelible stamps on the forehead and round the orbits of the men -examined. These are wrinkles which have been long in preparation and -only begin to show themselves fully when the “evil days” have come, in -the ’fifties, ’sixties and ’seventies. - -I will describe the wrinkles first, and then their results, with -examples, in the numerous fashions of the hairs. Wrinkles are of two -kinds, pathological and physiological, in other words the former are -the results of degeneration and wasting of the subcutaneous fat and -loss of its normal elasticity, and are found in the faces of nearly all -men and women, with advancing age, and they are the subject of much -distress in the fair sex and a good deal of “beauty doctoring.” The -latter are the result of long-continued and repeated action of certain -small muscles. The former are numerous, shallow and fine, the latter -few and comparatively deep. The difference between elderly women and -men in respect of the projecting hairs is not that men have many more -physiological wrinkles, but that the hairs of women in this region do -not stiffen and grow long nearly so much as those of men. - -There are three groups of wrinkles found on the human forehead and -face, _vertical_, _arched_ or horizontal and _orbital_. This division -of wrinkles is a natural one, for each group is produced by the action -of different muscles, the _vertical_ by the corrugator muscle, which is -a narrow band passing from under the frontalis muscle inwards, where it -is attached to the bone between the two eyebrows; the _arched_ by the -action of the frontalis muscle, one which moves the scalp and in doing -so elevates the eyebrows; the _orbital_ by the elliptic orbicularis -muscle which closes the eyelids. These muscles are shown in Fig. 20. - -_Vertical_ wrinkles are found in the central region of the forehead -and sometimes occupy the middle line with a deep furrow, more often -they are bilateral and symmetrical, near the inner fourth part of the -eyebrow, and sometimes they are placed at different distances from the -middle line. - -_Arched_ wrinkles extend over the forehead in a series of lines -which are usually concentric with the curve of the eyebrows, but are -sometimes nearly horizontal. - -_Orbital_ wrinkles may lie in a radiating plan all round the outer -lower and inner borders of the orbit, and in some persons they are -found lying over the curves of the orbicularis muscle itself. - - -Some Examples. - -The variations in the long hairs of men’s eyebrows present some very -singular tufts, and I have added below nine figures of certain cases -examined and noted by myself, and these are, I hope, plain enough -without any more detailed account than is given in the few words -describing each. - -Unless one’s attention be specially directed to these aberrant hairs, -which are extremely common, one would not expect that hairs could -be so variously twisted by muscular action beneath them. You may -see a tuft of long hair projecting from the plane of the eyebrows -towards the inner end, looking like a small horn, and I have measured -individual hairs in elderly persons and found many an inch in length -and a few an inch and a half. Such a tuft gives a fierce look to the -countenance if the hairs are bushy and plentiful. The celebrated Dr. -Keate, the flogging Head of Eton, a fiery strenuous person, was noted -for the extraordinary long horn of thick hair in his eyebrows, which -he appeared to use as a supplementary finger to point to this or that -object of his terrifying attention. You may also see a man with a great -drooping curtain of hairs overhanging his eyes, half hiding the upper -lids and eyes. Another will show at the outer end of the eyebrows a -bristling bush of hairs turning upwards in the aggressive manner of -Wilhelm II. of evil memory, or of Mr. Roosevelt in former times. Again -the outer points of the eyebrow hairs may turn downwards like a cavalry -moustache, or the hairs may stand out at right angles as a level shelf. -The fashions of these “orbital moustaches” appear to be as numerous as -those of the upper lip. - - -A Conflict of Forces. - -If the eyebrows are studied in the light of the three muscles displayed -in Fig. 20 it is seen to contain an interesting congeries of small -forces in conflict. (1) The _frontalis_ moves the eyebrow directly -upwards. I had a friend once about seventy years old who was a very -vigorous, strong-willed man and he spoke with decision and energy. It -was most interesting to watch how his frontalis muscle strongly and -frequently contracted as he spoke and drew up his eyebrows so that one -might, as it were, measure the strength of his expressed convictions -by the rate of action of his _frontalis_ muscle! (2) The _corrugator_ -draws the skin of the eyebrow inwards to the middle line thus acting -at a right angle to the line of the _frontalis_. (3) The _orbicularis_ -in the upper part directly opposes the action of the _frontalis_ and -in the lower acts “on its own” in closing the lower lid. This little -spot is a Hill 60, destroyed at the battle of Messines, and has been -the scene of much fighting throughout life, and it bears abiding -witness in the twists and curves of the long hairs to the severity -of the struggles. These actions of the three contending muscles are -involuntary and of a reflex character, and much employed in such habits -as those of knitting the brows or in elevating or depressing them, all -this being set going and controlled by cerebral action. Incidentally -then the preponderance of one or more of these actions over others, as -shown in the hair, is evidence, as far as it goes, of the disposition -and character of the possessor. So that between the wrinkles and the -twisted hairs of his brow the elderly man, and less so the woman, -carries about an engraved statement, for his friends or enemies to -read, of his natural disposition and his acquired habits, in a limited -field--his written character! - -[Illustration: Fig. 20. - -Muscles surrounding orbit with lines of action. Left--muscles concerned -in movements of parts round orbits. Right--lines of action of these -muscles indicated by arrows.] - -[Illustration: Fig. 21.--C. B. _æt_ 81. - -_Hairs_: Thick and bushy eyebrows. At junction of outer and middle -third of each side the thick hairs turn abruptly downwards in a tuft -and cover the upper lid. - -_Wrinkles_: Arched and lateral fairly well-marked, one very deep, -central and vertical wrinkle.] - -[Illustration: Fig. 22.--G. W. _æt_ 79. - -_Hairs_: On each side at junction of outer and middle thirds a definite -wisp of hair turning upwards. - -_Wrinkles_: Arched and orbital well-marked, central wrinkles hardly -visible.] - -[Illustration: Fig. 23.--F. F. _æt_ 57. - -_Hairs_: Left side two long hairs from 1 to 1-1/2 inches long, turned -sharply up at outer end of eyebrow. Right side short hairs turned -upwards. - -_Wrinkles_: Strongly marked, curved, orbital wrinkles round outer half -of each orbit. No other wrinkles.] - -[Illustration: Fig. 24.--B. W. _æt_ 69. - -_Hairs_: on both sides, projecting tufts at junction of the middle -and outer thirds of eyebrows, hairs an inch long. The outer fourth of -surface bare of hair. - -_Wrinkles_: Vertical hardly visible. Arched wrinkles numerous and -especially deep towards the temporal region.] - -[Illustration: Fig. 25.--T. R. _æt_ 57. Voluble talker, twitches -eyebrows in talking. - -_Hairs_: Thick and stand out stiffly from eyebrows, turning slightly -upwards in outer third--almost absent from inner third of surface. - -_Wrinkles_: Vertical faint; arched deep and long, equal on the two -sides, orbital, on each side two groups of deep radiating wrinkles, -beside many small lines.] - -[Illustration: Fig. 26.--A. P. _æt_ 63. - -_Hairs_: On each eyebrow at about the junction of the middle and outer -third, there is a remarkable tuft measuring 1 to 1-1/2 inch projecting -from plane of eyebrow somewhat upwards, scanty hair on outer third. - -_Wrinkles_: Smooth open forehead, with moderate-sized arched and -orbital wrinkles. Vertical wrinkles hardly visible.] - -[Illustration: Fig. 27.--G. G. _æt_ 54. - -_Hairs_: Right eyebrow upward twist of hairs on outer half, left -eyebrow hairs lie straight; project, on both sides, well away from -plane of eyebrow. - -_Wrinkles_: Arched on right side more numerous and extending higher -than on left. No vertical wrinkles.] - -[Illustration: Fig. 28.--R. N. _æt_ 65. - -_Hairs_: On right side hairs long and projecting nearly in horizontal -direction, on left sharply turned up at inner end and rather less so at -outer. - -_Wrinkles_: on right sides, three faint arched wrinkles, one vertical, -short and small. On left, three deep arched wrinkles, one vertical, -deep and long.] - - -A Side-Issue. - -This conclusion brings me to the piece of gratuitous advice I offer -to the unmarried reader. It will be more likely to appeal to the -woman than the man, I believe. Let such an one who is contemplating -matrimony make a short study of wrinkles and the long hairs if -possible--unfortunately she cannot do this of her prospective mate if -he be at all young, for neither of these features will be pronounced -as yet. I recommend instead a study of the wrinkles and hairs of the -father and mother and a deliberate summing-up of the evidence in this -way. If she wishes to have a cheery, genial, hopeful companion in -life like B. W. (Fig. 26) let her seek as many arched wrinkles in his -parents as possible and avoid very deep vertical wrinkles. If she be -herself of that disposition she will want a mate of different qualities -and may venture on one whose balance of family wrinkles inclines to the -vertical, _see_ Fig. 28, R. N. She can risk that, and perhaps get a -more capable and strenuous comrade in life’s battle. But let her beware -of him whose wrinkles are all of the vertical kind; for he will be -thoughtful, moody, abstracted and not too good-tempered. I would rather -myself join my fortunes to one who could claim a large share of arched -wrinkles. - -[Illustration: Fig. 29.--B. F. _æt_ 52. - -_Hairs_: On both sides much twisted downwards, producing shelf over eye. - -_Wrinkles_: None on forehead; strongly-marked concentric orbital -wrinkles on both sides.] - -After this digression, which follows logically on the facts and -arguments of this chapter I am now in a position to affirm that -_changes in the direction of the hair in the individual can be caused -by muscular action_. - - - - -CHAPTER IX. - -HABITS AND HAIR OF UNGULATES. - - -Horses. - -The Ungulate order has been variously divided by zoologists, and is -still said to be composed of two main sections, even-toed and odd-toed -Ungulates, with the addition of a good many “outsiders” if one may use -the term. - -These sections form two sub-orders, and the division suits my purpose -here very well. I take the odd-toed sub-order of the Ungulata Vera -first. - - -Lessons from the Domestic Horse. - -The domestic horse is the only member of this section that requires -detailed attention, and its value for studying the direction of the -mammalian hair is great, on account of the immense number of specimens -available, the quality and varied distribution of its hair, the size of -the animal, and, most of all, our intimate knowledge of its habits of -life for many thousands of years. - -Many volumes have been written by man about this, his best and second -oldest friend among lower animals. His ancestry, his story as servant -of man, his virtues, strength, speed, intelligence, his use for war and -peace, his colour, varieties of breed and money value; his anatomy, -physiology, pathology, his medicine and surgery have all been written -by many able men. Indeed before the great revelation of what man can -be and do that the great war has given us, many observers of mankind -were prepared to adapt the saying of a French cynic and to declare: -“The more I see of men the better I like horses.” Swift at any rate -came near this in his bitter account of a voyage to the Houyhnhnms, -which lasted sixteen years and seven months, towards the end of which -he said: “For who can read of the virtues I have mentioned in the -glorious Houyhnhnms without being ashamed of his own vices, when he -considers himself as the reasoning governing animal of his country?” -But in all these writings, even in that last striking book by Mr. Roger -Pocock, _Horses_, little or no attention is given to the patterns of -its coat from the point of view of science. I remember reading a -paper on this subject many years ago before a distinguished company of -veterinary surgeons, and though they had glanced at these patterns in -a passing way, as peculiarities, no real knowledge of them nor attempt -to understand them was shown by this body of experts. They were too -“practical” for this view of things. I may remark here that many of the -most vocal and active among us, and especially the Germans, have been -overmuch disposed to study science _ad hoc_, for its commercial and -military value, though here, as elsewhere one must be tolerant and each -follow his own taste, seeking light, more light. One must live and let -live. - -The horse does his work _coram publico_ in every street of every town, -in fields, roads and race-courses, and displays on his hairy coat some -graceful patterns which are at the same time subjects for scientific -inquiry, and brands of his long servitude to man. I have examined many -thousands of horses in some twenty years with never failing interest. -Belonging to the large family of Equidæ, including _asses_, _zebras_ -and _quaggas_, he is the most highly-developed of them all. His habits -first, and then the most notable of his hair-patterns must now be -considered. - - -Some Habits of the Horse. - -He has few habits which bear on the present subject, and of these his -active habits of locomotion are far the most important. He has his -share of passive habits, for he stands many hours a day, and often -sleeps standing, and he does his share in lying down, though Mr. Roger -Pocock says he takes no more than four hours’ sleep in this attitude. -His rule in lying down is to “lie anyhow,” if one may so describe it, -and thus his two passive attitudes of standing and lying, have little -or no bearing on the questions before us. His glory is in his gallop, -canter, trot and walk. His business is indeed a _going concern_ in -more than one sense, perhaps in three. The world is moving fast in its -old age, and some men are calculating how long it may take for him to -become as nearly extinct as the _quagga_. - -With the clue given to this inquiry in Chapter VI. we need have -little difficulty in tracing the manner in which his locomotive life, -ancestral and personal, is engraved on his hairy coat. We shall bear in -mind the _primitive direction of his hair_, _hair-streams_, _lines of -least resistance_, and the powerful forces of _underlying traction_ of -muscles, opposed or divergent. - -It is, of course, most convenient to examine a specimen with a -fine, short coat rather than one with its wild and more shaggy hair -remaining. - -The two regions where the play of great forces comes most powerfully -into action during locomotion are round about the elbow-joint (which -we should be disposed to call the shoulder) and the hip-joint, in -which regions the range of extension and flexion, as well as the -number of muscles engaged, is much greater than at any other part of -the limbs. It is in the neighbourhood of these two regions that the -most characteristic of all the patterns of hair are found, and the -names given to the patterns (whorls, featherings and crests) in these -critical areas are _Pectoral_ (Fig. 30) and _Inguinal_ (see Fig. 31) -with a third (G, H, I, Fig. 31) which is called _Axillary_, and is not -constantly present. The main muscles involved in Figs. 30, 31 are shown -in Fig. 33. The _Frontal_ (Fig. 32) is another of the critical areas, -_indirectly_ concerned in locomotion, and will be considered first. - -[Illustration: Fig. 30.--Front view of horse showing pectoral pattern -A, B, C.] - -The _Frontal_ pattern forms the star on a horse’s forehead, often -very noticeable when the hair of it is white. No detailed description -is required if the illustration of it in Fig. 32 be studied. It is -enough to point out that it lies at or very near the level of the eyes, -sometimes a little above and sometimes a little below this, and there -is occasionally a double whorl, the second lying above the normal one. - -[Illustration: Fig. 31.--Side-view of horse showing inguinal whorl, -feathering and crest A, B, C, and axillary whorl, feathering and crest, -G, H, I.] - -Fig. 32A shows the muscles of the fronto-nasal region of the horse -and the manner in which the skin of this central region is pulled -upon in divergent and opposing directions, by a long muscle, called -the _Maxillaris_, downwards and outwards, by a small thick muscle, -the _Corrugator_, inwards, by a deeper and more oblique muscle, the -_Nasalis_, downwards and inwards, and a little more remotely by the -_Temporal_ muscle, and the _intrinsic muscles of the mobile ears_. -There are thus at least five muscles on each side, all pulling more -or less against one another on this much-disturbed area of skin. The -struggle has been long ago given up and a compromise arrived at which -is registered in the frontal pattern. - -[Illustration: Fig. 32.--Frontal region of horse with frontal whorl -(_a_); feathering (_b_); crest (_c_).] - -[Illustration: Fig. 32A.--Muscles of the fronto-nasal region of the -horse.] - -Now if anyone doubts whether these comparatively small muscles act -often or strongly enough to produce effects on the hair over them he -need only consult Mr. Roger Pocock’s book to understand the story of -this battle of small forces and its result on the hair. - -[Illustration: Fig. 33.--Side view of horse, showing chief superficial -muscles.] - -In his wild state the horse is dependent to a remarkable degree -to his sense of smell for his safety from foes (Pocock), and very -much less so on his sight. Indeed that writer says his range of good -vision is about six yards. At that range his sight is of great value -to him for protection from certain of the dangers of his life, and we -see in a domestic horse to-day the evidence of his past wild life by -his rapid and keen glances at objects at the sides of the road, both -when we ride and drive him. His _corrugator_ muscle must be almost -constantly in action. But his sense of smell is the sling and stone -with which he encounters his Goliaths before they can get near him, and -he ceaselessly expands and draws up his flexible nostrils employing -his _nasalis_ and his _maxillaris_ for snuffing the air. He has also -much useful protection from his sense of hearing and we all know -how those mobile ears of his are hardly ever at rest, pointing now -forwards, now backwards, and again outwards, as he goes on his way. The -degree of these movements is largely a matter of individual character -and breeding. The case for a conflict of forces in this region is, I -submit, fully made out, and it is easy to see that a radiating pattern -of hair, such as there is in the simple whorl, is only the natural -outcome of all this complex muscular action. The extension of the whorl -upwards in the shape of a feathering which is sufficiently common, -indicates that the struggle has been carried beyond the original -battle-field by the muscles of the ears. - -The _pectoral_ (Fig. 30) pattern lies over the great fleshy masses -formed by the pectoral muscles, which draw the fore-limbs upwards -and inwards in conjunction with others in the actions of flexion and -extension of these limbs. The patterns, A. B. C., are wide expansions -of reversed hair beginning in the whorl (A), extending (B) upwards -and terminated in a crest (C). This pattern is, like the frontal, -invariably present in a domestic horse, and is shared by many other -ungulates such as deer and antelopes, as mentioned in the appendix of a -small book[49], I published in 1901. But in none is it so striking or -definite as in the horse. The contractions of these pectoral muscles -and their jolt at each step are easily observed in a trotting horse. It -is interesting to compare this pattern on the horse’s pectoral region -with what is found on the closely allied ass and mule. In the horse it -is long and wide and never absent, and is especially well-developed in -high-stepping horses whether cart-horses or others selected because of -their high action in trotting. Its size, indeed, is a measure of the -activity of the pectoral muscles and flexors of the fore-limb. In the -ass it is often absent, and, when it is present, it is rudimentary; -in the mule it is more frequently present than in the ass, but -does not approach the pattern of the horse for size. These degrees -of development in horse, ass and mule correspond closely with the -locomotive habits of the three animals. - - [49] _Use-Inheritance._ A. & C. Black. _Direction of Hair._ - -The _inguinal_ (Fig. 31) pattern is one which the most casual observer -of a horse cannot fail to notice, and it is so graceful in its shape as -to add to the many beauties of its possessor. But in spite of this no -breeder of horses has ever taken this pattern as one of the “points” of -the animal, so that here again selection, even of the artificial kind, -has had no share in its development. It is but a by-product of the -locomotive life of the horse, and a very ancient character, for it is -present in Przewalski’s horse, a probable ancestor of Equus Caballus. -A domestic horse without this pattern would be a freak of Nature. It -occurs in _equus hemionus_, the Thibetan wild ass, but not in _zebras_ -or in the _quagga_. - -The inguinal pattern deserves rather more description than the two -others. It is shown in Fig. 31 as A. B. C. and the muscles which -produce it and govern its development are shown in Fig. 33. It starts -in a whorl (A) at the fold of skin which passes from the lower part -of the abdomen to the hind limb. This radiates and expands into -a bilateral and symmetrical expansion shaped like the barbs of a -feather. This proceeds upwards in the inguinal hollow in a direction -which curves gently with the concavity forwards, dividing the trunk -of the animal from the great rounded mass of muscle forming the hind -quarters. It extends upwards to the level of the iliac crest where -a projection covered by muscles can always be recognised, and over -this “iliac crest” of the anatomist it terminates abruptly in a -ridge or crest of its own, lying parallel with the long axis of the -trunk. It is very pretty to see above it the hair-streams from the -back of the animal breaking away like two currents of water on either -side of an outstanding rock, the anterior passing with a wide curve -forwards and downwards along the flank and the hinder one losing -itself more gradually in the original course of the hair-streams of -the hind-quarters. No illustration or verbal description gives so good -a picture as one can get from inspection of the smooth coat of any -well-developed domestic horse. - -When a few trotting horses are watched by an observer who bears -in mind the accompanying pictures of the muscles and the inguinal -pattern it can be seen at once how all the conditions are present for -fulfilling a gradual change from a primitive slope of hair to these -highly-developed patterns, if he has also followed the conclusion -reached in Chapter I. that _muscular action can change the direction -of hair in the individual_. If at the same time the degree and extent -of the jolt which occurs here at every step be noted, it is seen to be -sharply limited to the area covered by this pattern, and ceasing, as -it does, abruptly and significantly at the level of the iliac crest. -The forward range of the jolt, easily seen in a thin horse, is much -wider than the backward, and marks out very closely the extent of the -forward curve taken by the anterior hair-stream as it descends from -the crest. One may also remark that there is a small but interesting -point which one can see during or after a shower of rain, for then the -flank of a horse presents a curious distribution of the moisture. At -the very point where the forward stream joins the main stream from the -thorax and abdomen a definite line of darker moist hair is to be seen -and the moist-looking surface is limited to the stream of the trunk -and separated from that of the flank. This line of demarcation clearly -indicates the place where the _forward jolt_ terminates during rapid -movement. - - -The Domestic Ass and Mule. - -There are two closely related animals, the domestic ass and the mule, -which ought to show this inguinal pattern if affinity and variation -could be fairly invoked to account for it on the theory of selection. -These are also animals whose mode of life is locomotive, but in a much -less degree than the horse and their paces are quieter and less free -in character. What then is found in them as to the size or persistence -of this pattern? In the ass it is absent or nearly so (I have found -one example of its presence), and in the mule it is variable and never -occupies more than half the area of that in the horse. These facts -agree closely with the hybrid character of the mule and the differing -activities of the horse, mule and ass. The pattern in Przewalski’s -horse is small and oval and resembles that of the mule. The _onager_ -(_equus asinus_), which is very much like these three domestic animals -in form, has an inguinal pattern, much less in size indeed than that -of the horse, but well-defined, and this fact is in keeping with its -character for remarkable fleetness of foot and activity. The three -zebras, Mountain, Grevy’s and Burchell’s, show no inguinal pattern, -in spite of their _power_ of rapid locomotion and resemblance in size -and form to the horse. Though they have that power they exercise it in -their wild lives for their own sakes alone, in the intermittent way -which is bound up with their habit of life, and not for the sake of -man, as in the case of the horse. - -The pectoral and inguinal regions of the domestic horse are two of -the most valuable fields in the mammalian body for studying the -formation by muscular action of patterns of hair, for this animal is -the locomotive animal _par excellence_. Here the process has been -carried to the extreme limit, and these two are prominent examples -among the characters to which I drew attention in a paper published in -the _Proceedings of the Zoological Society of London_, “On proposed -additions to the accepted systematic characters of certain Mammals,” -June 9th, 1904, Vol. I. I am still of the opinion that they deserve -“Flag rank,” though they have not yet been promoted. Be that as it may -I think it may be well here to compare two animals belonging to the -family Equidæ, the horse and zebra, which resemble one another very -closely in form--in respect of these patterns. - - -Horse and Zebra Compared. - -If a horse of the hackney type and a zebra were skinned and the bodies -of the two animals then examined I suppose a competent anatomist -would find some difficulty in distinguishing one from the other so -closely do these two allied species of equidæ, one wild and the other -domesticated, resemble one another in structure. But in this as in many -other questions _form_ is not to be considered alone. The colouration -of the two animals is strikingly different, but, in its humble way, -the difference of their patterns of hair-arrangement is worthy of -notice. The horse in different specimens chosen from a large group -will exhibit patterns in the frontal, pectoral and inguinal regions -constantly, and variably in less common regions, axillary, cervical -and gluteal, that is to say, in six different areas. I have examined -many zebras, living and dead, and find no constant pattern in the whole -of its large surface of skin except an ill-developed frontal and a -very small cervical one--_two in all_. The mere numerical difference -is not the only important one, for the insignificance of the size of -the two zebra patterns and the constancy and high development of many -of those of the horse are not less significant from the present point -of view. I submit that these two animals carry about with them on -their hairy coats indubitable records of their personal and ancestral -habits. Attention to the facts of a horse’s life and certain related -and contrasted facts of the lives of other animals, of which the zebra -may be taken as a type, will show the reasons why these patterns are to -be looked upon as registers of long-past and present activities of the -species concerned. The horse has been developed out of a wild plastic -stock with some such ancestors as the wild horse of Przewalski, lately -brought to Europe, by a process of selection by man during a thousand -generations, first in its Central Asian cradle and later all over the -civilized world. It has been as much _made by man_ for his purposes in -locomotion as a locomotive engine has been made by him. The one has -been produced in accordance with the laws of applied physics and the -other by those of biology. His locomotive life has come to pass for -the needs of higher, or at any rate more cunning creatures, who have -availed themselves of the potentialities provided by Nature. The zebra -in its habits differs from the horse in the simple, but fundamental -point that the former lives the ordinary active life of a wild animal -for its own needs of protection against foes and search for food, the -latter has not only this activity of life in its organisation, but has, -super-added to it by domestication, all the locomotive life of a beast -of burden. The zebra presents few, if any, of those phenomena which I -have often termed Animal Pedometers,[50] so characteristic of the hairy -coat of the horse I am reverting here again to the region of metaphor -for which I offer no excuse, but only a few remarks as to the use and -value of that elusive method of illustration. Metaphor is a figure of -speech or writing which consists in a transference of thought from -one idea to another. It is, therefore, not a simple substitution of -synonymous expressions, nor is it merely a simile. It is in hourly use -in the speech and writing of common as well as highly educated persons, -and adds much to the ease of communication among us of our thoughts -upon subjects which rise somewhat above the level of mere statement of -obvious facts. So long as metaphors are not abused by being used as -arguments to prove some proposition, but only as illustrations of our -meaning, we gain greatly by their legitimate use. It is not for nothing -the well-drilled Press of Germany in their journals and its histrionic -Emperor in his rhetorical outbursts, make extensive use of metaphors. -We are everlastingly reading of Germany’s “biological necessity,” her -“iron will to victory,” the “steel ring of field-grey heroes who guard -her against a world of devils,” of her “brilliant second,” her “granite -walls,” her “future on the water,” the “Admiral of the Atlantic,” -“grasping the trident,” and so on in nearly every public utterance of -her leaders. They know well their audience and employ these harmless, -if often ridiculous, expressions with a definite and legitimate -purpose, and are well qualified for creating the public opinion of a -nation that dearly loves a phrase. - - [50] _Knowledge_, January, 1903. - -Well, this term, Animal Pedometers, is used here not for proving -anything, but for the purpose of impressing on the mind of the reader -the fact of certain patterns on the horse’s skin being intimately -related to its locomotive life which, I hope I may assume, has been -sufficiently demonstrated in this chapter. A pedometer is one of those -works of men devised for his physical and mental advancement which are -marked by a precision as well as purpose often absent from Nature’s -handiwork. Just as a pedestrian, cyclist, or motorist carries with -him his pedometer and tells you with some pride the number of miles -he has “done” in a day or hour, so the horse displays _urbé et orbi_ -his rougher registers of the locomotive triumphs of his ancestors and -himself, and these I call Animal Pedometers by way of metaphor, and -patterns by way of fact. - -The less striking and rarer patterns of the horse’s hair have been -fully described elsewhere,[51] and it would serve no useful end to -refer to them at length, nor to multiply proofs of the position here -maintained. - - [51] _Direction of Hair in Animals and Man._ - - - - -CHAPTER X. - -HABITS AND HAIR OF UNGULATES. - - -Oxen. - -The even-toed section of hoofed animals is a much larger group than -the odd-toed, and the difference may be illustrated by looking at the -great work on Natural History by Lydekker. There are 273 pages given -up to this group and only 112 to the odd-toed, and when we remember -that there are contained in it the hippopotamus, all the pigs, oxen, -sheep, goats, antelopes, camels, llamas, giraffes and deer, we can see -that Lydekker was well justified in the great amount of space devoted -to them. But we all have our different forms of _penchant_, and I -propose to say very much less about this section than about the other -represented by the domestic horse. It is well to claim the shelter -of a great name in such an apportionment of interest, and Professor -Poulton has given a clear precedent in his great book called _Essays -on Evolution_. It contains 393 pages and even though the subject of -the work is Evolution, he has given up 330 pages approximately, or -five-sixths, of his space to insects. This can be gathered from a rough -analysis of his various essays, and no one need blame a great biologist -for having a _penchant_ for the subject he knows best, or a small one -for writing of that he knows a little. - -The reason that the even-toed ungulates require less study from the -present point of view is that they are so much more marked by the -normal or primitive slope of hair than the previous group of Chapter -IX. They demonstrate very widely and thoroughly the empire of the -primitive or “barbarian” forces and so far are valuable witnesses of -the negative kind. No case can well be proved to satisfaction by a -large series of negatives, and this was the hopeless task Weismann set -out to prove, when he staked his all on the non-inheritance of acquired -characters--and failed. But negative evidence is of great value in -supporting an hypothesis when it is found to be the precise complement -to extensive positive evidence brought in favour of that hypothesis. -That is the case in regard to the patterns of hair found on oxen, -sheep, antelopes, gazelles and deer, to say nothing of hippopotami, -pigs and llamas. There are some of these patterns described in the -previous group which appear in this larger one, but for size, -persistence and frequency they cannot be compared to those of the -horse, who has, if I may so say, inherited all the family property in -his own person and added to it. - -The variations in the present group are fully dealt with in the two -earlier books already quoted,[52],[53], and I will not complicate this -chapter by any further remarks on them. - - [52] _Op. cit._ _Use inheritance._ - - [53] _Op. cit._ _Direction of Hair._ - - -Oxen. - -Of the numerous divisions of even-toed ungulates the oxen present the -best cases for study of the various ways in which the hair is disposed, -and among them the best as well as the most accessible is the domestic -ox. Again we have a familiar friend of man and innumerable specimens -for examination as in the case of the horse. So this chapter will, like -the preceding one, resolve itself into the study of one typical animal, -with whose habits of life we are intimately acquainted. - -Before describing the habits and hair of the domestic ox or cow, I -would like to point out why I value so highly the negative evidence -which consists in the comparative rarity of whorls, featherings and -crests in even-toed ungulates. This brings us back to the general fact -of the _raison d’être_ of the horse and his group on the one hand, -and the ox and his numerous relatives on the other. There are deer, -antelopes and gazelles which for a spurt would beat any horse and even -the Thibetan wild ass, so I am not trying here to disparage the power -of this graceful swift group in the matter of sprinting. But this term, -however colloquial it may be, clearly marks off the powers and habits -of deer, antelopes and gazelles from those of the horse, for, except -when trying to escape from an enemy, no deer, antelope or gazelle -is fool enough to sprint or even trot for mere pleasure or want of -occupation, and certainly not in the service of man. Thus it comes to -pass that animal pedometers are few and small in this second group of -ungulates, and I submit this negative fact gives strong support to the -views advanced throughout this volume. - - -A Cow’s Habits. - -A cow is a very restful animal except when disturbed by extraneous -causes, and the active habits of her life are of little interest here, -the chief importance of her for study being the passive side of her -life or small minor tricks. As a domestic animal she lives to eat--and -be eaten and drunk--but her wild ancestors and relatives have had far -from an easy life, though this (in them even) has not expressed itself -in animal pedometers. But on her neck, back, flanks, legs and haunches -the cow has some interesting specimens of areas where the normal -hair-slope is reversed in accordance with her habits. - -The most striking of these is shown in Figs. 34 and 35, where the -bare form of the animal is shown and the dark thick arrows are made -paramount in order to make the remarkable arrangement of her hair along -the back so clear, that little verbal description is needed. - -[Illustration: Figs. 34 and 35. - -(A) Side view of cow, showing arrangement of hair-streams on the back. -(B) View of back of cow, showing the same.] - -Behind the level of the horns the normal or backward slope proceeds -until the middle of the length of the neck is reached, when it -encounters transversely a sharp upstanding crest and beyond this the -hair is directly reversed from a point over the shoulders, and here -a whorl is found. From this point the stream returns to its ancient -and normal course and so passes to the tail. When the base of the tail -is reached a very significant and apparently whimsical arrangement of -the hair down the centre of the tail is observed. This consists in a -line of stiff hairs which stand up at right angles to the surface of -the tail, and it gradually passes into the normal again when the more -muscular part of the tail is passed. I should add here that the crest -and reversed hair on the back are common to many wild ungulates of -this ruminant group, and a good example of it is seen in an antelope, -Oryx Beisa, which I figured and described in a paper at the Zoological -Society of London. - -Arrangements of its hair so audacious as these need explanation, and it -is found in the mode of life of the cow. So large a part of its daily -life is spent in the business of grazing with her muzzle close to the -ground, during which the neck of the animal is constantly stretched -downwards from the back at the level of the shoulders, that the skin, -which is very loose in this and most other portions of its body, is -dragged upon to allow of the extreme flexion of its neck. This traction -is for all this time acting against the normal or backward slope of -the hairs, and has given rise to this victory of a new force through a -thousand generations. It is equally clear that a mechanical explanation -of the line of erect hairs on the first nine or twelve inches of the -tail is forthcoming, for one has only to watch a cow standing on a hot -day, undergoing her torment of flies, to see it writ large. Very strong -little muscles are found at the base of the tail, those along the more -free portion becoming smaller and smaller until they disappear towards -the tip. These give a powerful flicking action to the long heavy tail -and I once made some observations as to this on a number of cows which -were grazing in summer on a comparatively cool wind-swept hillside -in the western end of the Isle of Wight. I watched several cows on -different occasions and found that one would flick her tail 348 times -and another 1082 times per hour. Giving these cows an eight hours’ -working day, “working” for their living in grazing and ruminating by -turns, one gains a vivid idea of the number of times per diem these -powerful muscles of the tail contract. If we call it a day of four -hours of grazing and four of ruminating, for the sake of argument, we -get 1392 to 4328 flicks of the tail each day in the time of flies, -leaving out of account the casual flicks in which she would indulge -when flies were not tormenting her. It is hardly necessary to point out -how the underlying muscles would drag upon the skin of the tail over -them and gradually reverse more or less the “lie” of the hairs. They -have not formed into a feathering or complete reversal, but have come -near to it. - -Further down the haunches of the cow there is on each side at the back -of the thigh a curving reversed area of hair which turns upwards and -towards the middle line. This is the place where the tail as it swings -from side to side sweeps over the limb and brushes upwards the hair of -the thigh towards which it is swinging. So that the activity of the -tail is responsible for another of the patterns in which the cow’s hair -is arranged. - -The lower segment of the hind leg exhibits one more reversed area of -hair due to the cow’s habit of lying on the ground slightly inclined to -one side, for the more comfortable disposing of her limbs, the effect -of this attitude being seen in the manner in which the hair on the back -of the leg turns inwards. - -On the dewlaps and flanks are certain variable curls and turns of hair -produced by the frequent twitchings of a muscle situated just under the -skin called the “Fly Shaker” or _panniculus carnosus_. This muscle is -seen any day in the carcase of an ox hanging up in a butcher’s shop, -and it is interesting to notice the fact that it is distributed over -only the lower half of the flank, for the purpose of shaking off flies -from a region which the tail does not reach efficiently. None of this -sheet of muscle is found within the effective range of the cow’s light -artillery, as on the haunches or hinder portion of the spine. This sums -up the equipment of patterns of hair on the species of this group of -ungulates, which is more adorned with them than any I have examined, -and it will be admitted that compared with those of the horse, it -is a poor exhibition, but one which it is easy to understand if the -fundamental principles of this inquiry are kept in mind. - - -Light Occupations of the Cow. - -I watched lately a little act of this drama among a herd of cows on -the Stray at Harrogate during a hot day. There were 105 of them and -this was what they were doing all day--some were browsing with their -muzzles close to the ground, their necks making a considerable angle -with the line of their trunks, others standing stock still with their -heads raised at a level with the body, gazing vacantly into space, -others lying on the grass more advanced in the strenuous work of their -day, ruminating with head level, also gazing at nothing in particular, -with their bodies gently rolled to one side, their fore legs doubled -straight under them and their hind legs planted to one or other -side, and a fourth group still nearer the end of the cycle of work, -lying with their chins resting on the ground. When this cycle was -completed the stages would again be begun, continued and ended. They -were flapping their wide ears in various directions, and twitching -endlessly the skin of the flanks and dewlaps with their fly shakers. -This large group afforded, if one may so describe it, a cinematographic -picture of the lives of countless generations of this conservative -animal. Conservative as she is, I doubt not that in the long-past -ages her quiet though persistent habits had once a battle to wage for -the production of even these mild innovations that I have described. -These present fashions must have been well developed three thousand -five hundred years ago and have adorned that “calf, tender and good,” -which Abraham in the plains of Mamre fetched for the midday meal of his -visitors. - - - - -CHAPTER XI. - -HABITS AND HAIR OF CARNIVORES. - - -Cats. - -Another large and important order of hair-clad mammals must now be -considered, and the same course as in the case of the ungulates will be -followed; the two leading families of Felidæ and Canidæ will be taken, -and a type of each examined in reference to its hair-distribution. -Lydekker gives about 100 pages to the cats and 80 to the dogs, so from -the point of view of general biology there seems little to choose -between them. The bears, racoons, weasel tribe, seals and walruses may -be put out of account. They are painfully old-fashioned or Normal as to -the arrangement of their hair. - -First things first is always a good rule, and there is little doubt -where we ought to begin among the families and species Carnivores. -Among Felidæ one cannot unfortunately choose the harmless necessary -cat of tiles, areas, firesides and ladies’ laps, to say nothing of -those lovers of cats like Huxley who would never eject his cat from -his armchair if she had been there before him. It is true that we know -much of her daily and nightly mode of life--many of us too much--and in -that respect one could set to work with confidence in interpreting her -hair patterns, but on account of her long and thick coat we can only -speculate what patterns or innovations of her family uniform she might -have devised; but here we are not concerned with romance or the “might -have beens.” It will be remarked that one perforce unconsciously calls -the domestic cat “she” as sailors do their ships. I understand that in -Somersetshire they call everything of their common life “he” except -the tom-cat who is always “she.” The reasons for the use of genders in -different creatures would be an interesting little study. - - -Lion. - -The King of Beasts will, therefore, be the hero of this chapter. -Lydekker tells us that the lion, like many heroes of antiquity who are -no heroes to their valets, in spite of his character for grandeur, -nobility and courage, has been subjected to the merciless higher -criticism of modern travellers, Selous, Livingstone, and others, and -he has been shown up as cowardly by nature and mean in his general -conduct. It remains for some learned scholar to whitewash the hyæna, as -someone has done for Caesar Borgia, and to put him in the place of the -lion. But Lydekker does not admit that this disparagement of the lion -goes very far. He _is_ the King of Beasts by grandeur of appearance, -strength and ferocity. - -[Illustration: Fig. 36.--Lioness, showing by arrows the direction of -hair-streams on muzzle, parting from one another at the level of the -orbits.] - -The lion’s skin is covered by close fine hair, except in certain -seasons in cold climates, and is easily studied. There are three -regions where this representative cat has departed from the Primitive -mammalian slope of hair, and the figure of a lioness shows two of -these, the peculiar _downward_ trend of hair on the muzzle and the -whorl on the shoulder. Fig. 37 shows the third, A C, on the middle of -the back as well as the whorls at D. - - -Snout of the Cats - -The muzzle of all the cats is very short and broad, and at the level -of the orbits shows a peculiar reversal of the hair from the rest of -the head, for instead of being like that of a dog in which the hair -slopes all the way _upwards_ from the tip of the snout to the rest of -the head, it breaks away from this normal type and passes in a uniform -close stream to the edge of the wet muzzle. The arrows in Fig. 36 show -this change. One asks at once the reason for such an unexpected trend -of the hair on a small area, when the carnivores in other groups have -a uniform slope towards the head from their more pointed muzzles. The -cats have discarded the earlier family pattern and for a reason which -does credit to their self-respect. Very few naturalists know, or have -described so well the meticulous care which animals take of their -coats, as Miss Frances Pitt did in the _National Review_, where she -gave a delightful account of “How Animals Clean Themselves.” The toilet -of the lion she did not discuss, perhaps for prudential reasons. Her -account dealt chiefly with a number of small hairy mammals and lower -forms of life. Watch a dog cleaning his coat and you will see the -ingenious way in which he pushes his head and body forward as he lies -on some rough surface such as grass, or our best drawing-room mat. _He_ -can thus clean his snout and other parts, but no cat adopts so rough -and ready a method. We know how long and how scrupulously she licks her -fur to clean it in the parts she can reach and cleans her head with her -paws. But with such a broad snout as she and the larger cats possess -she cannot clean the short surface of it in the manner of the dog. So -she “dresses” this little surface in a special way of rubbing it from -the neighbourhood of her eyes _forward_ with her paws. And so we may -assume does the chieftain of her clan finish off this little bit of -his toilet. We are so much accustomed to dwell on the naturally clean -habits of a domestic cat that without such an account as Miss Frances -Pitt has given we should have hesitated to transfer the character for -personal cleanliness from the domesticated to the wild cat. If this be -not the sole reason for the course of the hair-stream I have described, -I am at a loss to imagine any other. - - -Lion’s Neck. - -On each side of the lion’s neck where it joins the shoulder there is -a well-developed whorl, and this as a rule is extended forwards into -a feathering (Figs. 36 and 37), and ends in a crest on the lower part -of the side of the neck. It is common also in tigers and leopards. -This is, as elsewhere, a record of strong and oft-repeated action in -powerful muscles which lie beneath it, and bears witness to the great -functional activity of the fore-limbs as compared with the hind-limbs -in these three formidable cats. It is not an animal pedometer, but may -perhaps be termed an _ergograph_. - -[Illustration: Fig. 37.--Back of Lion, showing reversed area of hair -with whorl at A. Feathering B. Crest C.] - - -Lion’s Back. - -The strange pattern of reversed hair (Fig. 37) is much the most notable -of the three peculiarities found on the lion’s skin. It consists of a -whorl (A) lying over the lumbar region in the middle line which expands -into a very broad feathering (B) and terminates in a crest (C) a short -distance behind the level of the shoulders. This is not found in any -of the numerous short-haired Felidæ that I have examined, and it is a -feature which demands explanation. I know no other mammal, ungulate or -carnivore, that has any pattern resembling this; indeed, if one were -to photograph the pattern in question and a few inches of the skin -surrounding it, and be told that it came from the back of a mammal -one could not doubt that it was a hall-mark of the King of Beasts. It -would not produce that thrill of intense interest which we felt at -the meeting on 7th May, 1901, at the Zoological Society of London, -when from a water colour sketch and three pieces of skin taken from -the body of a hitherto unknown mammal, Sir Harry Johnston proceeded -to reconstruct the Okapi, at first dubbed knight, as a member of the -Equidæ, but later promoted downwards to the Giraffidæ. But one could do -no less, with some knowledge of the hair of mammals, than reconstruct -from such a photograph a large, powerful and ferocious carnivore, and -where but in the lion can the greatest example of those attributes be -found? I say this advisedly, for this remarkable pattern of the lion’s -back is as much a stamp of his moral or mental quality as the Inguinal -Pedometer is of the locomotive _rôle_ in life of _equus caballus_. - -I hear the sharp voice of the critic here, “Come, come, you may have -shown reason for the latter, but how on earth do mental and moral -qualities of an animal come into your scheme?” Well, we have in this -pattern of the lion’s back to deal with a unique phenomenon for the -production of which neither pressure, nor friction, nor gravitation, -nor underlying muscular traction will account. Nevertheless, it is -a result of muscular action of a rare kind. Who does not know the -striking appearance of the hair along the centre of a short-haired -dog when he bristles up with rage or fear, or both combined, at the -sight of a foe? This common event has its own mechanical cause, though -it is one strictly governed by the mental and moral qualities of -the dog, and we see the vivid proof before us of the action of the -minute _arrectores pili_, in this particular region of the dog. It is -precisely in the same situation that the special pattern of the lion’s -hair is found. It is not for nothing that Nature has provided every -tiny hair of the mammalian skin with that insignificant little band of -muscle which lies within the hair-pit, and is attached to the sloping -hair on its posterior side, and thus when it contracts serves to drag -it into an erect position. I refrain from discussing what may be held -to be the survival value, under the theory of selection, of this power -of the _arrectores pili_ to confer on the possessor an added appearance -of ferocity and general frightfulness. This is quite a likely -explanation of the presence of these little muscles. Be that as it may -the _modus operandi_ of the reversed hair which has become fixed on the -lion’s back is made clear, theory of origin apart. And I submit that -the presence of it in this region in this animal _is_ a stamp of his -persistently ferocious nature, as much as the various peculiarities of -arrangement of hair on man’s eyebrows in a previous chapter are of the -mental and moral habits of the individual man. As rulers of old used, -in their genial fashion, to brand a supposed or actual criminal on his -shoulder or forehead, so is the lion branded with an hereditary mark of -his nature and the past life of himself and his ancestors. I doubt not -that if short-haired terriers were living a wild life among numerous -foes their bristling hair would have become fixed in a similar fashion. -I would only here draw the attention of the reader to the fact that -this reversed area of hair on the lion’s back cannot be held to add to -the general frightfulness of the possessor. It would be invisible to -an approaching foe, as it lies hidden behind the great head and mane. -This pattern on the lion’s back will be referred to later in a somewhat -different connection. - - - - -CHAPTER XII. - -HABITS AND HAIR OF CARNIVORES. - - -Dogs. - -Among the canidæ one is able to select a type with whose habits of -life we are more familiar than any other, Canis Familiaris, as he is -affectionately called, the companion of man his master, and faithful -guardian--often unto death. Professor Scott Elliott gives reason to -think that the dog was the first animal tamed by man, and that he was -descended from some wild jackal-like form, probably crossed by the -wolf. The dog is then aptly called by Huxley, the brother of the wolf, -who has been changed by the intelligence of man into the guardian of -the flock. It seems that in his rudimentary stage of domestication he -was an unofficial scavenger among the habitations of neolithic man, -as the pariah is in the East to-day, and that little acts of kindness -towards his offspring on the part of those early men and women were -the first dawnings of a friendship of thousands of years. It is a long -story from the slinking jackal to the bloodhound, mastiff, St. Bernard, -staghound, collie and terrier of to-day, and one which reflects much -credit on both parties to this friendship, just as do those other -long friendships between servant and master, of which we still see -a few examples. Living with us as he does the dog and his habits -of life are an open book: he is then all the better for my humble -purpose here. I would refer again to the curious use of the gender -which we unconsciously apply to the dog. It is no longer “she,” but -“he.” When a dog is looking a little unfriendly how we always try to -wheedle him with “Poor old fellow,” and so on, as a matter of course, -assuming his masculine character. James Payn pointed out once a little -point which proves how good a comrade we have in the dog, when he -reminds us of the cautious approach we usually make to a cat, and the -“hail-fellow-well-met” tone we adopt towards the dog, rolling him over -and using kindly opprobrious terms, such as friends among schoolboys -hurl at one another when they are on the best of terms. A fox-terrier -is, perhaps, the most human of all the numerous types evolved through -the skill of man, and it is a smooth-coated specimen of this variety -which I will examine now as to what his hairy coat can tell us of his -habits. - - -Some of the Dog’s Habits. - -His attitudes which bear on this question are all of the passive order. -His locomotion is so fitful and different from that of the horse that -we shall find on his coat no animal pedometers. - -[Illustration: Fig. 38.--Gluteal region of dog, showing whorls over the -tuberosities of the ischia.] - -His passive attitudes consist of standing, sitting and lying. He stands -little, sits more, and lies for a great part of each day. The standing -habit has, of course, no influence upon his hair. In sitting he rests -the chief weight of his body on the rounded, bursa-covered surfaces of -his tuberosities of the ischium, in which there is nothing peculiar to -himself. His fore legs are planted nearly upright on the ground and his -hind legs doubled under him or projecting slightly to one or other -side, as we saw in the case of the cow. The fore legs are obviously -in no way affected as to the direction of the hair in the sitting -posture, and the hind legs, being doubled up and subject to the direct -downward weight of the body, are also free from the _sliding pressure_, -which we shall see affects the fore limb when the dog lies prone. Thus -of the three supports, fore legs, hind legs and tuberosities of the -ischium, two are necessarily unaffected in their patterns of hair. The -anatomical conditions of his tuberosities are very different in this -respect. They are covered with a large slippery bursa just beneath -the thick skin, and the slightest movement of this alert and restless -animal, even of his head, conveys to this region a small change of -position. He is virtually like a sick person on a water or air cushion, -and we all know how very small movements of the body are felt in a -slight stirring of the supported parts by these. The effect of this -is that the hair over these bursæ is seldom at rest from external or -extraneous forces, to say nothing of its own imperious constant growth -of one inch in two months. In Fig. 38 one sees the hair-stream curving -round the buttocks towards the region of these bursæ, and trying to -reach the middle line. It meets with so much opposition that the very -conditions for producing a reversed area are present and the result is -just what one would expect to find. The pattern is formed exactly over -the bursæ limited to this area, and it does not expand anywhere because -there is no need for it to do so. So when one observes on the surface -just below the tail a pattern, often in a black-and-tan terrier marked -by a tan patch of hair, one reads the record of the long time spent by -the dog in sitting as he meditates on some fresh or past escapade of “A -Dog’s Day.” - -The statement just made that the hind leg does not share in the effects -of pressure is not strictly correct; it applies to the _leg_ properly -so called. But the upper part of the thigh exhibits a very clear -reversal of hair due to the weight of the body acting here against the -streams from the side of the thigh, which are seen endeavouring to make -their way to the inner side. They are arrested by a long ridge of hair -which marks the obstacle presented by the weight of the body acting -here. This completes the story of the way in which sitting affects the -hair of the dog, and is shown in Fig. 38. - - -Lying Attitude. - -[Illustration: Fig. 39.--Foreleg of domestic dog, showing reversed hair -on under surface, which rests on the ground in lying posture.] - -[Illustration: Fig. 40.--Showing chest of domestic dog, with reversed -area of hair on each side.] - -There are four attitudes adopted by the dog in lying. In the first, -when he sleeps he lies stretched out on his side on some surface, with -his limbs projected nearly straight out, and in the second, he curls -himself up in _his_ armchair in a cosy, rounded posture. But in both -these attitudes there is no such sliding pressure as will affect in -any way the direction of his hair. In two other favourite attitudes -it is far otherwise. When he lies prone he plants his fore limbs out -before his chest and either raises his head to the level of his trunk -or rests it on his fore paws. Each of these attitudes contributes to -a very well-marked change of the hair on the under surface of his fore -arms, to use a convenient human term, one which carries us back to the -story of man and the apes when their fore arms were discussed. On this -surface, from the mechanical conditions involved, a new force, that of -_sliding pressure_, comes into play. The skin here is very loose, as -indeed it is in the greater part of his body, which may almost be said -to form one large subcutaneous bursa. The weight of the fore part of -his body and head acts _downwards and forwards_, and thus opposes the -normal or downward course of the hair on the limb, such as one sees on -the upper surface of his fore arm. The resultant of these two forces -has the effect of acting against the normal slope, and a reversed -direction of the hair is produced very much like that which is seen -in many monkeys and in a small area in man. This is shown in Fig. 39, -which appeared in the small book[54], to which reference has been made, -and it is confined to the part of the limb where the sliding pressure -is seen to act. In this feature again there is a record of his resting -habits, and, of course, the time he spends in the fourth attitude with -his chin resting on his fore paws contributes its share, the mechanical -conditions being similar. - - [54] _Use-Inheritance._ - -This fourth attitude brings in another force of its own towards the -“make-up” of the dog’s patterns of hair. When lying with his head -supported on his paws the lower part of his chest is closely applied to -the upper or flexor surface of the fore legs, and the long-continued -pressure of the latter against the downward or normal streams of hair -on the chest leads to its slope being reversed. This is shown in two -wide patterns of the whorl, feathering and crest, Fig. 40, resembling -closely the corresponding patterns on the chest of a horse. I had -the opportunity many years ago of examining in the Capitol Museum at -Rome two fine sculptures of Molossian hounds, when these matters of -hair-arrangement were occupying my attention, and was much struck with -the fidelity with which the ancient sculptor reproduced such small -facts as the reversed areas of hair in a dog. Phiz himself was not -more true to Nature in his delineation of the projecting hairs on the -human eyebrows. It should be added that the reversed hair in question -occupies only that part of the chest which is in contact with the fore -limb. If one cannot reckon any animal pedometers, to the credit of the -domestic dog I think one may fairly and metaphorically say that his -hairy coat gives an accurate mould of his habits. - - - - -CHAPTER XIII. - -HABITS AND HAIR OF PRIMATES. - - -In spite of the satires of Swift we may not cavil at the natural pride -which has led man, Homo Sapiens, as he also calls himself, to confer -boldly on himself, and his lineal ancestors at any rate, the name of -Primates. This large and highest group of hair-clad mammals includes -broadly and somewhat loosely lemurs, monkeys, apes and man. The last -has not lost his hairy endowment, though it is sadly curtailed, and it -is well to remember that, except on the palms of the hands, the soles -of the feet and the terminal rows of phalanges of fingers and toes, man -_is_ a hair-clad mammal. Shakespeare calls him “paragon of animals,” -and Huxley “head of the sentient world,” and no reasonable person will -attempt to improve upon such pregnant tributes to his greatness. I -desire only to adhere that _quâ animal_ he is the best of all for my -humble purpose of historian of the chequered course of the mammalian -hair, better even than the domestic horse. His hair varies from a coat -so fine as to need a lens for the discovery of the separate hairs, to a -truly Simian profusion of thick and long hair such as that of the Ainu -or hairy aborigines of Japan. - - -Hair and Habits of Man. - -The streams of his hair demonstrate two important facts about man: -first _what he has been_; secondly _what he has done_, that is to -say, his ancestry and habits of life, through an immense stretch of -time. These stories in hair are the culmination of a large number of -characters inherited and acquired, and their study in two selected -regions of lemurs, apes and man will be pursued in this chapter on the -lines which I laid down in Chapter VI. I have thought it well not to -give any connected account of the rest of his hairy covering so as to -concentrate attention on the two simplest and most striking regions. -The charts of his hair-streams and those of the lemur and ape have been -described with sufficient fulness elsewhere,[55] and no cartographer -has hitherto sought to improve upon them. - - [55] _Direction of Hair in Animals and Man._ - -The back and the front surfaces of the trunk afford the two best and -most instructive fields of study, for the forces which act upon them -are of a simple kind, and may be traced upwards from the lemurs to man -as in the case of the forearms. The three drawings (Fig. 41) represent -the backs of a lemur, chimpanzee and man, most of the details of the -hair being omitted and their place taken by thick dark arrows which -show the line of the different hair-streams. This diagrammatic method -will make any misunderstanding of the main facts impossible. - -The lemur has on the back of its neck a forward or headward slope -of hair and this passes on to the head itself, and on the back of -the trunk, as the arrows show, there is no departure from the normal -arrangement of the lower mammals. The lemur, therefore, requires -neither further description nor explanation. - -The ape shows no material change in this region from the arrangement of -its lemur or monkey ancestor, in spite of the greater proportion of its -life which is spent in the upright posture; indeed, this is what one -would expect. - - -Hair of the Back of Man. - -When the hair on the back of man is examined a remarkable change from -the patterns of any of his known or supposed ancestors is found. It is -by no means easy to trace the course of the hairs on the human back. A -young, hairy and dark-haired person gives much the best field, and a -lens may be necessary. In older subjects the hair is often so much worn -away by friction that the direction can no longer be followed. Suffice -it to say that the examination, though somewhat difficult, can well be -carried out if the proper conditions are observed; and that it bears -out the results which have come from the corresponding examination of -infants. _The arrangement is congenital._ - -From the neck the hair passes on each side nearly downwards, and in -the middle directly downwards in a narrow stream between the two -muscular borders of the vertebral furrows, and continues in this -normal direction to the end of the spinal region. It will be seen -that below the two upper arrows there are three levels of arrows, the -first with one, the second with two, and the third with one, on each -side of the surface of the back. At the level of the shoulder-joints -the side-streams curve upwards towards the spine and join the central -stream; at the second the direction is rather more upwards before it -curves inwards and downwards to the vertebral furrow; at the third the -streams curve slightly upwards and towards the middle-line and coalesce -with the other streams. The contrast between the straight, simple -slope of the hair on the lemur’s and ape’s back, and that of man is -very great. In the latter the side-streams make an angle of 45° or -less with the axis of the spine and _this arrangement is unique among -mammals_. It will be, therefore, necessary to inquire into its history -and causation, for it goes far towards reversing the well-established -and accredited pattern of apes, monkeys and lemurs. If the reader will -carry his mind back to the arrangement of hair on man’s forearm he will -see that it exhibits some features analogous to those on the back of -man. In the forearm there is that curious little stream on the extensor -surface which may be looked upon as a relic from the ape-stock, but -in the rest of that limb-segment man has boldly gone back, beyond the -ape, to an arrangement found in the lemur; and in the case of the back -of man there is the small primitive area down the vertebral furrow and -an entirely novel arrangement on each side such as might startle the -leaders of animal fashions in hair. - -[Illustration: Fig. 41.--Arrangement of hair on the back of -lemur--chimpanzee--man.] - -The question at once arises: “How has this change come to pass?” In the -case of the strange arrangement on man’s forearms I have shown that the -Pan-Selectionist thought he detected there one of his particular kinds -of vestige. He cannot find any such here. I can conceive a biologist -making play with Heredity, Variation and Selection in the case of an -ape, monkey, or lemur whose hairs are long and thick and functionally -very active. _There_ he might make use of the well-known “argument from -ignorance,” and maintain that we cannot be sure that such and such -factors might not have survival-value, but I defy the most hardy among -the Pan-Selectionist High Command to put in that plea in connection -with the fine short hairs of man which even require a lens for their -detection; they have little value as a protection of the skin from -friction; their arrangement has none. And if some leader did attempt -this task I doubt if the most docile Prussian would not rebel against -the statement that the withdrawal in question was “according to plan.” -My purpose, however, in this book being to build up and not to pull -down, I must perforce show a reasonable and better explanation of a -remarkable little fact. - - -Passive Habits. - -The habits of man concerned in the _modus operandi_ of this change are -passive, and two in number; that of sitting with his back against some -supporting object, and of lying in sleep with his head more or less -raised on a pillow or its equivalent. In contrast with man, lemurs -and apes inhabit trees during their many hours of rest, and I doubt -if the number of hours thus spent by these and other wild animals -to that spent in active exercise is less than three to one, so that -their attitudes of rest would, if calculated to do so, contribute much -towards any change occurring in the patterns of hair. But, seeing -that the ape-fashion is similar to that of the lemur, and that this -normal arrangement is calculated only to be confirmed by the action of -gravity and the dripping of rain, and that they do not greatly indulge -themselves, if at all, in their equivalent for man’s armchairs, nothing -else would be expected in the hairy covering of their backs than what -we find. - -The increasing tendency to the upright position in Eoanthropus Dawsoni -and Pithecanthropus Erectus to say nothing of the men of Cromagnon--led -man to use as supports for his back the walls of his rough caves which -he had adopted as dwellings instead of the branches of trees and the -nests of the ape. He no longer affected entirely those hardy habits -of sitting without support for his back that were _de rigueur_ in his -ancestors, who probably looked upon him with as much disapproval as -certain erect old ladies of the old school display towards the use of -easy chairs by the rising generation. Wearied with the struggle for -food, and against his savage rivals, he rested his back against the -sides of his rude abode. When he slept in this attitude the relaxation -of his voluntary muscles allowed mechanical forces to come into action -which tended to oppose the downward trend of the hair. We know from our -own experience that when sitting asleep with our backs supported there -always occurs a certain amount of sinking down of the trunk. In this -attitude are present, then, such conditions of the back and its hairy -covering as give rise to mechanical forces which would interfere with -the direction of the hair. These are, a heavy body, tending to slip -downwards slightly while resting against a fixed surface, a growing -tissue easily diverted from its normal course, and many hours spent in -the attitude in question. - -The effects of these conditions increased with the increasing tendency -of developing man to attend to his bodily comfort. - -But man spends also on the average at least a third of his whole -existence lying in sleep with his head on a pillow of some kind, -perhaps the skull of a _Felis Groeneveldtii_ in the case of -Pithecanthropus Erectus, and other such better objects, as he made more -study of the art of being comfortable. Those who know much of children -and sick persons and have watched them in sleep know that the habit -of lying on one or other side prevails largely over that of lying on -the back. The head being more or less raised by a pillow, the human -sleeper, even when lying on his back and more so when lying on his -side, is in a potentially and actually sliding position, a fact well -known to most persons from their own experience. It is easy to see -how such conditions are tending for a third of a man’s whole life to -reverse in some degree the direction of his hair and how they act as we -saw in the case of the sitting posture. But the very common _lateral_ -position in sleep contributes its own peculiar share in pushing the -hair towards the spine, ceasing to do so only when the prominent -muscular border of the vertebral furrow is reached. I think it will -escape no careful observer of these simple facts of man’s resting life, -who also notes the remarkable course of the arrows on his back, that -the facts and their present explanation fit one another like a Chubb -lock and its key. The only alternative suggestion of the facts is that -some being with diabolic power has been at work and laying a trap for -poor human biologists in the 20th century A.D. - -In confirmation of this process I would refer to an example which -agrees very closely with the above explanation. I knew an invalid -suffering from pleurisy and lung-disease who was much confined to bed, -spending much of his time propped high up on pillows. He had long dark -hair on his back and I was often struck, when examining him, with -the remarkable way in which the hairs were dragged upon so that they -pointed nearly in a vertical _upward_ direction. Here was a little -instance of an undesigned experiment in the dynamics of hair. - - -Hair of the Chest. - -In the hair-streams on the chest of our chosen three, lemur, ape and -man, there are also some remarkable contrasts in the course they take. -Fig. 42 shows these in a vivid manner. Precisely as in the case of the -hair on the backs of lemurs, apes and man, we find on the chest of -those three types a normal direction on the two lower ancestors and an -entirely novel arrangement in man; the former, therefore, will need no -verbal description. - -Man, the ever bold explorer and innovator has initiated on his chest, -as on his back, a fashion in hair unknown in any of the primates. He -is, in respect of his hair on these two regions, _sui generis_. On -the chest there is a critical area extending across the sternum at -the level of the second rib from a whorl which is found on each side -somewhat above the nipples. This is not less an ancient battle-field -than the Border which separated England and Scotland, and it has been -the site of its little conflicts, more especially _north_ of the -Border, corresponding to those of the wild days of Border warfare of -which Scottish history is full. - -[Illustration: Fig. 42.--Arrangement of hair on the chest of -lemur--chimpanzee--man.] - -At this level of the chest two streams of hair are _directly_ opposed -to one another. That which covers the chest below the dividing line -maintains in true old English style its conservative fashion and passes -downwards as in the ape and lemur. The more independent or Scottish -stream goes upwards on its way to the neck, the side streams passing -somewhat outwards towards the side of the neck, the central upwards and -inwards, converging gently on to the front of the neck. The arrows in -the figure show this very clearly. On the front of the neck the stream -pursues its upward way until it meets the downward flowing stream -from the lower jaw, and the _junction_ of these two streams lies over -the level of the upper border of the larynx in front, winding gently -outwards and upwards to the surface just below the lobes of the ears. -The opposition of the two streams in the neck is very familiar, as a -piece of practical experience, to those who shave, for it affords a -decided little resistance to the razor as it is drawn downwards, and -many persons change the position of the razor in consequence of it, -without troubling their heads with any scientific reason for the fact. - -These are the facts of the distribution of hair on man’s chest, but -what is the interpretation? I would remark here that in my former -book[56] I gave what seemed to be then the best reason for it, but -further reflection on the matter has shown me that it was incorrect and -inadequate. I refer to this and one or two other corrections of earlier -views in a later chapter. - - [56] _Direction of Hair_, pp. 88–93. - - -Interpretation of Records. - -In discussing such a striking little fact as the one in question, an -illustration may serve as an introduction. From the glaciers of Mont -St. Gothard two great rivers take their rise. The eastern side of its -slopes gives rise to the Rhine, which flows in a northerly direction -to the Lake of Constance, the western to the Rhone, whence it pursues -a south-westerly course to the Lake of Geneva. No geographer would -doubt that certain physical features of the country were to be sought -in accounting for the contrary courses of two rivers arising from a -comparatively small region, and he finds it by a simple study of the -topography concerned. By similar methods we must ascertain why from our -little Mont St. Gothard at the level of the second rib, two streams of -hair separate and pursue nearly opposite directions. - -A little knowledge of the superficial anatomy of the chest and neck -throws some light at once on the problem. It so happens that if one -made a simple map of these hair streams, and at the side of it a -drawing of the platysma myoides muscle, it could not fail to strike -one that the correspondence of the surfaces occupied by the two -phenomena was very significant. It is going too far to say that the -correspondence is complete, but it is so nearly so that one may fairly -say that the reversed stream of hair which begins at the second rib -and goes up the neck, lies over the platysma muscle. The stream of -hair does not extend up to the lower part of the face and lower jaw, -it does not cover the outlying portion of the platysma on the side of -the neck and it begins on the chest a little above the rather uncertain -origin of the platysma fibres from the fascia of the chest. But the -correspondence of its surface with the main part, or about five-sixths -of the platysma, is most suggestive. - -This muscle is one of the subdermal sheets that are found in many -mammals, and though it is not a continuation or descendant of the -fly-shaker or panniculus carnosus, which is often referred to in these -pages, it is an analogous feature of man. It is _closely attached_ -at its lower part to the skin over it and more loosely at its upper. -It has various functions attributed to it, as I will mention later; -but there is one effect of its action which is very evident in a thin -person, that is to say, it wrinkles the skin over it in a vertical -direction. This it does, whatever else it may do. - - -Struggles of the Platysma. - -In interpreting this novel hair stream of man’s chest and neck we are -again brought into an atmosphere of struggle of forces. Something has -occurred in the course of man’s descent from the ape to interfere very -sharply with the course of the hair; and certainly if there be anything -in organisms that Heredity, Variation and Selection are unable to do -(even when adorned with capital letters, to make them, as Huxley said, -“like grenadiers with bearskins,” appear much finer fellows than they -are), it is to provide in this reversed stream of hair on man’s chest -some cunning “adaptation” to his needs. Selection will not serve; but I -think use and habit will. There can be little, if any, doubt that the -frequent and active contractions of the platysma muscle in the course -of man’s life are the efficient cause of the change of arrangement of -hair from a downward simian to an upward human slope. To this opinion -the anatomist will promptly reply: “Ah! I have thee there, friend -Lamarckian; are there not any number of apes and monkeys that also -have an active and efficient platysma?” Undoubtedly there are, and I -give here, through the kindness of Professor Keith, a short account -of that muscle in simiadæ. It is taken from an unpublished work of his -on _The Myology of the Catarrhini--a Study in Evolution_. The account -may be only interesting to the professed anatomist, but the conclusions -in the summary bear closely on the present problem. I give the exact -words from Chapter II., pp. 472, 479. The simian forms examined are -_semnopithecus_, _gorilla_, _chimpanzee_, _orang_, _gibbon_, _macacus_, -_cercopitheci_, _cynocephali_. “_Summary_: Every gradation is found -between the cynocephalic and human forms. The evolution lies in the -disappearance of the supra-trapezial origin and the superficial -labio-mental insertion. The opposite nuchal and mental angles of a -trapezoidal sheet are obliterated and a rhomboidal figure is left. The -change may be seen step by step through the _macaci_, _semnopitheci_, -_hylobates_, _troglodytes_ and the _orang_ to Man. - -“The maxillary insertion in man is more extensive than the others, and -the insertion is more distinctly demarcated from the quadratus menti -origin. But slips between the two muscles are not uncommon. - -“The sub-mental interdigitation occurs frequently in man, and although -its extent varies in the other Catarrhini it is always present. - -“The upper nuchal fibres, being cut loose in the higher members of -the orthorachitial group from their primary origin, became aberrant -in their behaviour. Auriculo-labial slips, slips of union with the -zygomatici, or simulating a _risorius_, or a relapse to the primitive -medial dorsal origin and connection with the occipito-auricular muscles -may occur in man as in the others. - -“Fasciculation of the muscle may occur in man and the _troglodytes_. - -“That the functions of this muscle are indefinite is shown by the -numerous individual and generic variations. But that its presence is -essential may be judged by its persistence. It may depress the angle of -the mouth or the lower jaw, or help to flex the head upon the chest, or -help to empty the laryngeal air-sac if it be present. But as a matter -of fact all these functions are otherwise provided for. When tense it -protects the deep part of the neck somewhat, and it is usually active -in temper. The axillary part of the same sheet in the _cynomorphæ_ -offers a similar puzzle as regards its functions.” - -We have it thus on the highest authority that the platysma muscle is -active and persistent in a large series of monkeys, apes and man. But -the whole work has for its sub-title, “A Study in Evolution,” and -in the story of the platysma there is a picture of its progressive -development to that of man. There is evidence in the above account -of the muscle that a structure is found in monkeys and man which -might operate on the overlying streams of hair in any of these animal -forms--or might not--in accordance with the conception of struggle -between opposing forces which I have kept in view all through this -volume. - -It is evident that in all animals below man the platysma has not -achieved any victory by its action over the streams of hair on the -chest and neck, and to my mind it is equally evident that in the case -of man it has carried through a very manifest “turning-movement.” It -will be objected, quite properly, that this is a matter of opinion, -and the pertinent question will be asked, “How do you account for the -absence of this reversed hair-pattern in apes and monkeys and its -absence in man, both having an efficient platysma muscle?” - -The essence of a struggle is that it ends with the victory of one -adversary over the other, and as the race is not always to the swift -nor the battle to the strong, there is of necessity some uncertainty -as to the result of any struggle. The factors of time as well as of -overwhelming force are required for most of the victories of man over -man, and it is not less so in the victories of habit over ancestry in -the direction of hair, as I have repeatedly shown. The required time -is clearly at one’s disposal for this victory, and the “overwhelming -force” of habit and use is purely a question of the degree of -repetition and the efficiency of the contractions of the platysma, and -its greater use in man than in apes and monkeys. The uses to which it -was put in the lower forms not having been sufficiently overwhelming -for victory, no change in them has been shown. The cumulative effects -of the actions of a developing platysma in man, under the guiding -influence of his more complex habits of life, have turned the scale in -favour of the reinforced forces of habit, and the direction of the hair -becomes reversed nearly all over the area covering the muscle. - -We must consider all the forces engaged in this struggle for mastery on -the neck and chest of man, and remember on one hand the power of the -normal slope of hair, the greater difficulty of altering the direction -of the thick long hairs of monkeys and apes, and their relatively -long resting hours; and on the other the shorter and finer hairs of -man and the increasing efficiency of his platysma muscle in varied -actions. Professor Keith mentions four functions of the platysma: that -of _depressing the angle of the mouth and lower jaw, helping to flex -the head upon the chest_, and to _empty the laryngeal air-sac_, and -_protecting the deep parts of the neck when it is tense_--adding the -significant comment that “it is usually active in temper”--I presume -this to mean bad temper! - -Leaving out of account the emptying of the laryngeal air-sac, is it not -evident that the remaining three actions of the platysma are very much -more exerted in the case of man with all the numerous occupations and -movements of his head and neck, in obedience to his higher brain, than -in the apes, monkeys and lemurs, endowed with a fitful activity, with -fewer and less variable movements of their head, and long, long hours -spent in their particular form of meditation? - -So, when the muscular sheet, which, as I have said, is _closely -attached to the skin of the chest and more loosely to that of the -neck_, contracts and becomes shortened between its origin on the -chest to its insertion in the face and jaw, it gives a most obvious -pull on the skin over it and wrinkles it vertically in a manner which -will strike any thin person who contracts it voluntarily before a -looking-glass. The connection shown between the action of the platysma -muscle and the change of hair is so close that it can hardly be -questioned that one is the cause of the other. If it be not proved to -demonstration it is “tremendously probable” and the connection falls -into line with the previous demonstrated cases. - -I must add here a remark suggested by the views of man’s descent put -forward since this was written. The claim that man has changed the -direction of his hair on his back and chest by use and habit owing to -altered modes of life is not dependent on the simian theory of his -descent. The change to his present patterns on those two regions from -those of any “active arboreal pioneer” among insectivores is just as -striking and is open to the same line of explanation. - -It would serve no useful purpose here to travel further over the varied -streams of hair on the body of man. - - - - -CHAPTER XIV. - -MISCELLANEOUS EXAMPLES. - - -In this chapter a few of the rarer examples of hair-clad mammals which -present remarkable changes at critical areas of their hairy coats -may be considered with advantage. I have chosen six, of which three -appeared in my former book. - - -The Giraffe. - -The two drawings of a giraffe, Figs. 43 and 44 were made for me for the -purpose of illustrating one of its habits and two of its peculiarities -of arrangement of its hair. This stately creature is the tallest known -animal and is the sole representative of its ancient family, more -common in the days when giants abounded. Its range is becoming more -limited and its enemies not less dangerous, and it is expected in the -course of some years to add to the number of the recently-extinct -creatures. - - -Habits. - -Living mainly in dry sandy regions giraffes find their food exclusively -in leaves plucked from trees, and are said by some authorities to exist -for a long period without drinking, but an interesting account quoted -by Lydekker from Selous should be mentioned here. Selous writes that -on a certain occasion he reached camp “a little before sundown, just -in time to see three tall, graceful giraffes issue from the forest a -little distance beyond, and stalk across the intervening flat, swishing -their long tails to and fro, on their way down to the water. It is a -curious sight to watch these long-legged animals drinking, and one that -I have had several opportunities of enjoying. Though their necks are -long, they are not sufficiently so to enable them to reach the water -without straddling their legs wide apart. In doing this, they sometimes -place one foot in front, and the other as far back as possible, and -then by a series of little jerks widen the distance between the two, -until they succeed in getting their mouths down to the water; sometimes -they sprawl their legs out sideways in a similar manner.” Lydekker -adds that this position has to be assumed not only when drinking, -but likewise when the animal desires to pick up a leaf from the ground -or on the rare occasions when it grazes. This habit so graphically -described is the one which alone concerns my subject. The patterns of -hair peculiar to the giraffe need a short description. - -[Illustration: Fig. 43.--Giraffe showing at A and B, hair-patterns of -a remarkable kind at the place where the main movements of the neck -occur.] - -[Illustration: Fig. 44.--Giraffe in the act of drinking or browsing off -the ground.] - - -Hair Patterns. - -Fig. 43 shows a whorl (B) at the side of the neck on a level with the -prominent spines of the seventh cervical and first dorsal vertebræ. It -lies exactly over a spot which may be well called a “critical area,” -for an important hinge of the whole mechanism of the giraffe’s great -neck is situated here. Though the remarkable length of its neck is -intimately associated with its daily needs for protection against -enemies and the supply of food from high-placed branches of trees, it -forms a real obstacle to the less important need of obtaining water -to drink or food from the ground as Selous and Lydekker show. The -protective value of the neck is picturesquely described by Mr. Beddard -when he speaks of it as the giraffe’s watch-tower, whence its keen -eyesight surveys the surrounding country for its enemies. But its -attitude in drinking, Fig. 44, gives a vivid idea of the play of forces -which takes place at the great hinge between the neck and the trunk, -and at this point the whorl has been produced on the skin in the course -of its laborious efforts to supply itself with water. The absence of -any other whorl or reversed hair on the whole of its neck and trunk is -most significant from the point of view of the dynamics of hair. - -The second departure from the normal direction of hair is found on -the prominent portion of the spine, and it lies over this hinge-area. -In Fig. 44 is shown the mane proceeding along the whole of the neck -in the normal downward direction, and the arrows indicate the way in -which it becomes suddenly reversed at the critical point and the lowest -portion of the mane stands up and points upwards. This change is shown -by the two arrows whose points meet one another, and the facts of its -occurrence, here and nowhere else, at once suggest that the habit which -produced the whorl on the side of the neck has also contributed to the -change in the direction of the mane. The pattern here is precisely of -the same order as that of the cow’s neck which we saw to be caused by -its habit of browsing off the ground. - - -Bongo--Tragelaphus euryceros. - -This West African antelope is a forest-dwelling species, about which -little is known as to its habit of life, though its form and anatomy -are well described by Lydekker. It has a powerful chest, long and -strong horns, and short hoofs, and it is shown in Fig. 45 with its -large pectoral whorl, feathering and crest, in which it strongly -resembles the domestic horse. One may be allowed here, as exact -knowledge is wanting, to point out that “reconstruction” of its habits -may be reasonably attempted along the lines laid down in these pages. -It is doubtful if any large mammal could possess so powerful a fore-end -with very muscular forelimbs, highly-developed pectoral patterns and -short strong hoofs without being a very fleet animal much accustomed to -relying upon its speed for its protection, and if a greater knowledge -of it be obtained in the future it is highly probable that this -prediction will be verified. Part of its habitat is described as the -Ashkankolu Mountains, a region where speed would be of great value. - -[Illustration: Fig. 45.--Bongo. Showing on the strong muscular chest, -well-formed pectoral patterns.] - - -Kiang--Thibetan Wild Ass. - -This member of the Equidæ is shown in Fig. 46 and there is an excellent -specimen of it at South Kensington. I have chosen it because it is very -unusual among others of its family in the possession of an inguinal -and axillary whorl, feathering and crest. No other than the domestic -horse that I have examined shows these patterns. They are nearly as -well developed as in the horse, and require no special description. It -lives in high altitudes up to fourteen thousand feet, and travels often -in large herds, its food being composed of the various woody plants -of these dry and barren regions. Lydekker says that it “is remarkable -for its fleetness and its capacity for getting over rough and stony -ground at a great pace.” From these facts one can gather that a large -portion of its working day would be spent in rapid locomotion from -place to place in search of its sparse food-supplies and in avoiding -enemies--two paramount objects of its existence which are pictured in -the two animal pedometers displayed on its hairy coat. - -[Illustration: Fig. 46.--Kiang. Side view showing inguinal (W F C) and -axillary (W F C) patterns.] - - -Llama--L. - -I refer here to the true llama or domesticated form of the genus Llama, -of which the vicunha and huanaco are the existing wild species. In the -stirring time when a handful of Spanish Conquistadores under Pizarro -conquered and trampled upon the ancient civilisation of the Incas this -useful animal was employed to an immense extent as a beast of burden. -Lydekker says that at the time of the Conquest of Peru it was estimated -that three hundred thousand llamas were employed in the mines of -Potosi alone. Prescott gives an excellent account of the use of this -animal in his _Conquest of Peru_. They were valued highly for their -strength and sureness of foot which were much needed in their long and -rugged journeys over the great passes of the Cordilleras, as well as -for the excellence of their flesh. - -[Illustration: Fig. 47.--Fore foot of llama shown from behind (A) and -from side (B) with whorls of hair and reversed areas on each side.] - -The only region of a llama’s body which is of interest in the present -inquiry is the fore-foot, figured in Fig. 47. It presents a very -remarkable arrangement of hair on its under surface, just above the -double hoof and spongy pad at the joint above the hoof. This is -found on each side towards the outer border of the hollow region, -and consists of a whorl from which the hairs radiate in a reversed -direction towards the upper part and transversely across the rest -of the hollow. Prescott speaks of “its spongy hoof, armed with a -claw or pointed talon to enable it to secure hold on the ice,” and -adds that “it never requires to be shod.” If one reflects upon the -ceaseless action during rough and slippery locomotion of this animal -throughout its working life on mountain passes, on rough stony paths -and ice-covered places, one can have no doubt of the reason why this -particular joint, so greatly used in maintaining a foothold, should -have acquired on this sheltered portion of its hair an animal pedometer. - - -The Parti-coloured Bear--Æluropus Melanoleucus. - -This is a rare and peculiar form of the family of Ursidæ about which I -made a statement some years ago at the Zoological Society of London. -It is a “stocky” animal with a small head and broad short muzzle, a -feature to which it has no right according to its affinities. It is not -a member of the high-class Felidæ whose special prerogative it is to -wear their hair on a short broad muzzle in a _downward_ direction as -I showed in Chapter XI. Being a more _bourgeois_ creature than a cat -it has offended against such sumptuary laws as may exist in the animal -kingdom. - -Its hair ought to be worn in the proper backward or upward slope such -as other bears, dogs and small carnivores display. - -In my former note I modestly proposed an alternative suggestion to the -one I now offer, of this aberrant and strange bit of hair-country, -and this was that it was correlated with the broad short snout. As I -have remarked before this word “correlated” is used so loosely as to -mean almost anything the user likes, and it is, in my opinion, a fine -source of confusion of thought. Undoubtedly this shape of the muzzle -of the Parti-coloured Bear is linked somehow with the arrangement -of its hair on that region. But it is hardly to be imagined that -a direct reversal of hair from the proper bear-type, that is to say -from the mouth to the head, would be produced by the mere broadening -of the muzzle on account of some adaptation to its altering life. The -link surely is of a different nature, and analogous to that of the -corresponding surface in the lion and other cats, and that the cleaning -of its fur on the snout is done in feline and not in ursine fashion, -that is to say forwards, and that the breadth of muzzle is the reason -for the change of method. - - -Two-Toed Sloth--Cholæpus didactylus. - -This weird creature is one of a decaying family whom naturalists, with -needless and frank brutality, called toothless. The term is neither -exact nor polite. It is very much as if one were to call a person -“toothless” whose front teeth had been knocked out, but whose remaining -teeth were good and useful. But it represents so important a taxonomic -character that one must allow for what seems bad manners on the part -of zoological leaders who are, as a rule, full of the milk of human -kindness, and seldom in these days quarrel even among themselves, -adopting the motto _nihil animalium alienum a me puto_. - -[Illustration: Fig. 48.--Two-toed sloth, showing action of gravity upon -the long thick hairs.] - -The sloths form an excellent example of the action of gravity upon long -thick hairs, and the Fig. 48 given will explain this. They are New -World animals, though indeed they have what we call an “Old World” -look, and are truly ancient. They spend the larger part of their -time upside down in the manner represented in the drawings. They are -arboreal and nocturnal animals that come down to earth in search of -food when things are quieter below, and will wander for considerable -distances, walking slowly on the outer borders of their feet and the -feet turned in. - -These being the few facts of their lives which concern the present -subject one comes, as usual, to interpretation. These tree-sloths are -descended from an older form that inhabited the ground, so that the -present mode of life, which is so largely arboreal, has been acquired -by dint of long years of struggle and adaptation to bitter needs. -It seems hardly reasonable to call in the aid of selection for the -production of its singular disposition of hair though that factor ruled -in the production of its arboreal habit. It is almost flying in the -face of common sense to attribute this upward, or downward (according -to one’s point of view) singular arrangement to anything but the -effects of gravity upon its long hairs. If it be not so, it looks a -remarkable likely solution of this small problem. - - - - -CHAPTER XV. - -EXPERIMENTAL. - - -About ten years ago I began an investigation into the results of the -application by man to the domestic horse of various forms of harness, -desiring to find out if these results were capable of being transmitted -from one generation to another. In 1908 I had not got very far, but -thought it well to bring before the Zoological Society of London the -results observed up to that time and read a paper entitled, “Some -observations on the effects of Pressure upon the Direction of Hair -in Mammals.” It was kindly received, but was not published in their -proceedings, as it appeared to the Publication Committee a paper more -suited to “another place,” presumably those of a veterinary society. -It was illustrated by the two figures I give here of a horse in full -harness, and another with the chief results as to changes of the -direction of hair, or new patterns, displayed on its coat. - - -Progress of Inquiry. - -Being disposed to think that the investigation could be carried -further, I proceeded to look about for any examples in horses which -might show the transmission of these artificial results to their -descendants, and had to wait awhile before I could see which of the -regions affected by the pressure of harness were likely to afford the -required phenomena. These were in due time forthcoming, and will form -the chief subject of the present chapter. I look upon them as cases of -an _undesigned experiment_ and will describe them later. - -In the present stage of science all hypotheses must be submitted to -the test of experiment before they can enter the charmed circle of -natural laws. For this reason one must endeavour to apply the test of -experiment to the hypothesis before us. - - -The Nature of Experiment. - -Hitherto I have gone no further than the region of experience and -observation, from which, Jevons says, “all knowledge proceeds.” There -has been abundance of observation of phenomena in this quest and I -have ventured even on hypothesis. Experiment is shortly defined by -Jevons as _observation plus alteration of conditions_. He points out -that when we make an experiment we more or less influence the events -which we observe, as when we bring together certain substances under -various conditions of temperature, pressure, electric disturbance or -chemical action and so on, and then record the changes observed; and, -that experiment may be of two kinds, experiments of simple fact and -experiments of quantity. It is unnecessary here to describe all the -rigorous rules that the man of science so rightly imposes upon himself -before he claims to have proved his hypothesis, merely adding that -among others he requires, Exclusion of Indifferent Circumstances, -Simplification of Experiments, Removal of Usual Conditions, -Removal of Interference of Unsuspected Conditions, Blind or Test -Experiments, Negative Results of Experiment, and he lays down the -limits of experiment. Those who have not for themselves investigated -some scientific problem may learn from this statement some of the -difficulties of the work of scientific men and will not fail to respect -and admire the caution, patience and honesty of the scientific worker, -and will perhaps feel the more gratitude to a class of men by whose -self-denying labours they live and move and have their being in a -modern state, and by whose discoveries, thus established, they are -frequently preserved from premature death. - - -Experiments for the Present Purpose. - -Now in the matter of experiment for the proof of the thesis that -changes in the habits of an animal _cause_ the changes observed in -their hair, it is at once seen that, _ex hypothesi_, no one can impose -and work with such calculated conditions as are ordained by experiment, -strictly so-called. The action of a habit is a slow process and the -movement of a hair is slow; moreover the lifetime of a man is too short -and that of a horse, for example, too long to allow of any individual -experimenter applying artificial pressure through many generations of -horses, so as to be able to verify his assertion that the effects of -artificial pressure do what is claimed, and that these effects are -transmitted from one generation of horses to another. One can conceive -a calculated experiment of the kind made with numerous individual rats, -and successive generations, but it is hardly likely that effectual -pressure could be applied to the hairy coats of such small and elusive -mammals as would serve to test the hypothesis. - - -Undesigned Experiments. - -We are thrown back, then, on such experiments as may be provided -for us by the uncalculated operations of man through many ages. -This class I call undesigned experiments and have had more to say -about numerous examples of these in another place.[57] Using the -term experiment broadly we see many occurrences which consist in an -accidental observation of a fact, and Jevons mentions five of these -which have led to organised results in science--the double refraction -in Iceland spar by Erasmus Bartholinus, the twitching of a frog’s leg -under stimuli by Galvani, the light reflected from distant windows -with a double-refracting substance by Malus, the form of a vertebra -by Oken, and the peculiar appearance of a solution of quinine by Sir -John Herschel. But he notes something further than this, that is, -the way in which astronomers make the earth’s orbit the basis of a -well-arranged _natural experiment_. He says further that “Nature has -made no experiment at all for us within historical times” among animals -living in a state of nature, allowing at the same time that man has -made an approach to experiment in his domestication of many animals. -Huxley himself kept an open mind until the last as to the validity of -Natural Selection in the Origin of Species, because of the fact that -races which are sterile together have not yet been produced by human -cultivation, for example, the sterility of mules, the human product of -the jackass and the mare. I allude to this to show that such a result, -if effected, would have constituted a valuable experiment in biology in -favour of Natural Selection. - - [57] _Contemporary Review_, June 1917. - - -Harness on Horses. - -Man has, however, been carrying on unconsciously throughout a great -stretch of time an experiment upon the hair on the coat of a horse -by the use of harness. This is an old story and its rudiments are -mentioned by Professor Scott Elliott.[58] He states that the men of -Cromagnon are believed by a high authority as to their rock-paintings -to have depicted some marks which represent rude harness of some kind, -though he himself expresses doubt on the matter. He also quotes the -same authority for the figures made by the Madelenians as having found -signs which can be interpreted as halters or even bridles. Be this as -it may, we need not carry our search for the use of harness to this -hoary antiquity, but know well from history that for many thousands -of years man has been employing harness on his friend and servant, -thus making the essential conditions for an experiment of which he and -his servant were alike unconscious, that is to say, he influenced a -growing living structure, the horse’s hair, by the artificial force of -pressure, applied to the coat at various points. These varied from age -to age as to fashion and material, and the present full development of -harness of a draught horse was probably slow in coming. - - [58] _Prehistoric Man and His Story._ G. F. Scott Elliott, 1916, - pp. 169, 206. - - -Examples of the Effects of Pressure. - -Looking at the figures of a horse harnessed, and another without -harness, Figs. 49 and 50, one sees on the latter eight different -regions where patterns of hair, not found in the horse normally, are -displayed. They are as follows:-- - - A. The under surface of the neck. Pattern due to the collar. - - B. The hamstring region. Pattern due to the kicking - strap. - - C. The hollow corresponding to Pattern due to strap of - what we should call the saddle. - armpit. - - D. The coccygeal or tail-region. Pattern due to the crupper. - - E. The side of the neck. Pattern due to the reins. - - F. The shoulder. Pattern due to the shaft. - - G. The side of the face. Pattern due to strap of - head stall. - - H. The border of the neck _under_ Pattern due to collar. - the collar. - -All these aberrations from the normal are rare except the first -(A), and all are based on the observation and drawing of individual -specimens which I brought before the Zoological Society and the details -of which are given in a note on page 129. The rarer seven examples are -described because taken together they show what the pressure of harness -_can_ do at certain points where its pressure is adequate, and they -are all situated where they might be expected if such a force could -effect hair-changes, and there are _none of them found on areas where -neither pressure nor underlying muscular traction_ can act efficiently. -Thus in many thousands of horses I have never seen a hair-pattern on -the middle of the flank or the under surface of the abdomen or the -middle of the back or gluteal region or on the fore or hind legs. This -negative evidence is of great importance, and must be taken for what it -is worth. I may venture to remind the reader that every one of these -phenomena is an artificial product of man’s treatment of the horse. -They come thus under the category of undesigned experiments. - -The only one of the eight artificial patterns, which as a rule are in -the form of a whorl feathering and crest, that needs, further close -attention is the pattern A, produced on the under surface of the -horse’s neck by the collar, and this will be examined separately. - -[Illustration: Fig. 49.--Domestic horse, fully harnessed.] - - -The Selected Example--Ventral Surface of Horse’s Neck. - -If I set out to convince a doubting opponent that these things are -as I assert, three conditions may at once be laid down. First, it -must be shown that the patterns found here are not part of a normal -arrangement. Second, that they are produced by pressure of the harness. -Third, that examples of them be forthcoming in young horses never -exposed to the action of harness. - -[Illustration: Fig. 50.--Side view of domestic horse, showing eight -areas of reversed hair, A, B, C, D, E, F, G, H, all of which were -situated under portions of the harness. - -B. Pattern on hamstring region, under the breeching. - - Examined 24th December, 1907. Roan hackney, recently clipped, - showed on the offside on the hamstring region, a reversed area - of hair proceeding vertically upwards and ending in a crest, in - the position where the breeching rubs during locomotion. Thirteen - cases examined, other twelve similar. - -C. Pattern on lower axillary region, under belly-band. - - Examined 4th March, 1907. Small grey hackney with reversed area of - hair in lower axillary region, with also a crest nearly horizontal - lying along upper part of this area under the belly-band. Eight - cases examined, the other seven similar. - -D. Pattern on tail region. - - Examined 29th November, 1907. Bay hackney, on each side of base of - tail where the crupper rubs during locomotion, is a wide reversed - area of hair five to six inches long, in which the hairs were - arranged at a right angle with the axis of the spine on the upper - border and feathering out on the lower border into the general - stream of hair. Three cases examined, two others similar. - -E. Pattern on side of neck under the position of the reins. - - Examined 21st December, 1907. Small mouse-coloured hackney recently - clipped. On the offside of the neck where the reins rubbed against - the neck there was a wide reversed area of hair with a well-marked - crest in front. Five cases in all examined, the four others - similar. - -F. Pattern on shoulder. - - Examined 15th September, 1905. Bay cart-horse, reversed area lying - nearly horizontal under the shaft of the cart; hairs formed into a - whorl, feathering and crest lying posteriorly--pattern four inches - in length, on near side only. One case only examined. - -G. Pattern on side of face. - - Examined 25th May, 1905. Grey hackney with wide reversed area of - hair along side of face ending above in oblique crest, under a - strap of the headstall, on the offside only. Two cases examined, - the other similar. - -H. Pattern on border of the neck under the collar. - - Examined 28th September, 1906. Bay cart-horse. On near side under - the collar which was lifted up while the horse was resting, the - hairs at the border of the neck were formed into a large whorl. - One case only examined.] - -_First._ The normal arrangement of hair on the under surface of the -horse’s neck shows an even stream passing from the head to the chest, -where it is interrupted by the pectoral patterns, and during that -course resembles precisely the other normal streams in this and other -mammals. - -The opponent asks, “How do you know this is the normal slope, and -that the patterns you describe are not normal, and what you describe -as normal is not a variation?” This is a perfectly proper and timely -question and can only be answered fully by examination of and noting a -large number of draught horses. - - -The Normal Arrangement on the Ventral Surface of the Horse’s Neck. - -This examination has been made in a number of specimens large enough -to satisfy the most exacting opponent. In all, 748 were examined -as to the hair on the under surface of the neck and 338 of these -presented the normal arrangement and 411 showed patterns of various -kinds ranging from a trifling reversed area two to three inches long -on one side of the middle line, to a finely-formed whorl, feathering -and crest occupying the whole of the surface where the collar is able -to reach. These two limits are shown side by side in the figures. I -should add that among the 411 which I term abnormal, for the sake of -clear contrast, the number of varieties of pattern were numerous and -bewildering. - - -Cart Horses. - -A very significant result followed from a special examination of -300 cart horses, as distinguished from hackneys. These showed the -astonishing number of 277 specimens of what I call the abnormal and -only 23 of the normal type. This special group in no way weakens the -force of the larger study of 748, for the 300 cart horses are included -in it, and, if removed, would have left the normal specimens in the -hackney or general group very much more numerous. Looking at the cart -horses, which are specimens of a highly-specialised breed for heavy -draught purposes, one may assert with some confidence that, _for them_, -the normal pattern of the hackney is becoming their abnormal. It must -be remembered that these great creatures with large muscular necks are -during most of their time of work pulling hard against the collar, -and the very conditions required for making patterns of hair through -pressure of harness are present in a remarkable degree. It is indeed an -_undesigned experiment within an experiment_. - - -Analogy. - -In addition to these statistics which may be taken as conclusive on -this question of the normal arrangement, I must point out that it is -against all reason, and analogy from _all other_ mammals, to doubt that -the normal arrangement is as I describe it. No hair-clad mammal either -within the family of the Equidæ, or without, has any other arrangement -on the under surface of its neck than what is here shown to be the -normal one--a uniform uninterrupted slope from the head to the chest. -There is also a feature of this greatly variegated piece of the horse’s -coat under its neck, and that is that it is so highly variegated -with diversity of pattern as to make it unlike any normal or natural -structure or character in any animal. _That_ is not the way Nature does -her normal work. It would be impossible to give illustrations of many -of the patterns here found, though I have notes and sketches of a large -number taken from the examination of thousands of specimens; so I have -selected eight (Figs. 51, 52, 53, 54, 55, 56, 57 and 58) of the best -representatives of these and the details of each are given under each -figure. - - -Effects of Pressure by Harness. - -_Second._--The next stage of the inquiry demands that one should show -the patterns to be due to pressure. - -[Illustration: Fig. 51.--Roan cart horse, examined 25th September, -1914. On left side of middle line of the under surface of the neck a -short reversed area three inches long, lying vertically--none on the -right side.] - -[Illustration: Fig. 52.--Grey cart horse examined 25th September, -1914. Long central feathering (F) proceeding vertically upwards in -middle line of neck from whorl (W) and ending in a crest (C) at the -upper limit of region, through which the collar can move in active -locomotion.] - -In the accompanying drawings the under surface of the neck and the -chest of each horse is shown with the collar in place, the centre -portion of which is cut out so as to show the arrangement of hair -beneath, and some of the varieties are seen to extend for several -inches above it. In considering this process one ought to watch the way -in which the collar of a horse, as a rule, is seen to move up and down -as he trots, for in most cases, except in cart-horses, the collar fits -very loosely and is easily jolted upwards. This will explain why the -patterns often extend upwards above the proper position of the collar, -but it must also be remembered that _never_ have I found a pattern -higher up in the middle of the neck than a loose collar can reach when -jolted. (Close to the lower jaw there is a whorl or pattern often found -which belongs to a different category, and is not to be confused with -the patterns in question.) - -[Illustration: Fig. 53.--Brown hackney, examined 9th October, 1914. -Small reversed area of hair lying under collar in middle line of under -surface of neck, passing vertically upwards three inches long, in -central position.] - -[Illustration: Fig. 54.--Brown cart horse, examined 25th October, 1914. -Whorl, feathering and crest (W F C) in middle line of under surface of -neck, beginning below where the collar should lie in usual position.] - -In the conditions described there is present exactly that frequent -pressure of a moving body against the growing hair, which is requisite -to produce changes in its direction, as well as the more fixed pressure -of the collar when it is fitting firmly against the lower part of the -neck. - -By way of confirmation of the view that this is the _modus operandi_ -one has only to point to the other seven regions shown in Figs. 49 and -50, in which the connection between the pressure of harness and the -production of a new pattern is beyond all doubt one of cause and effect. - -[Illustration: Fig. 55.--Brown cart horse, examined 25th October, 1914. -Whorl, feathering and crest (W F C) in middle line of under surface of -neck beginning underneath collar and proceeding vertically upwards for -six inches.] - -[Illustration: Fig. 56.--Bright bay pony, examined 29th October, 1914. -Very muscular neck. On under surface on each side a wide curving stream -of hair passing towards middle line and joining in a central upward -stream ending above in a tuft (T).] - - -The Proof of Transmission of Pattern. - -_Third._--To show that the effects produced by pressure in one -generation are sometimes inherited by its descendants it is necessary -to examine a few examples of young horses who have never borne the yoke -as yet. - -[Illustration: Fig. 57.--Brown hackney, examined 29th October, 1914. -On under surface of neck beneath the lowest portion of an ill-fitting -collar, a wide area of reversed hair on each side coalescing in a -central upward stream.] - -[Illustration: Fig. 58.--Brown hackney engaged in drawing a low Swiss -cart, with loose collar low on neck. Examined at the Croix in Jura -mountains, 24th September, 1912. On lower surface of neck under the -collar three reversed areas observed; one central (F), two (W, C) -central and similar; all three showing a whorl, feathering and crest: -central area placed vertically, lateral ones slightly oblique. _A very -rare condition._] - -I examined some mares of the farm-horse type with their foals in a -field at Radley in 1915 with the following results. All the mothers -showed the common reversed area or pattern on the under surfaces of -their necks. Of the five foals all but one showed clear evidence, even -in their thick young coats, of a similar pattern, the fifth had none. -I also noted two similar examples in a field at Harrogate in the same -year and both the mothers and the foals showed the usual pattern; -and again at Radley in 1918 four more foals, one of them 24 hours -old, who all showed this reversed area. Here then are ten examples -of undoubted transmission of the effects of pressure by harness in -subjects so young as to be still suckled by their dams, and, of course, -never themselves touched by such pressure. I submit that even one such -unmistakable example would be enough to prove the case, and that the -necessary conditions of a rigorous undesigned experiment by man have -been fulfilled. - - -Objections. - -At the end of this chapter which concludes the facts of the case I -think it may serve to make the position a little clearer if I state -objections which have been or might be raised. - -It will not escape the mind of any person who has followed critically -this process of inquiry, that in Chapter VII, where the immense variety -of the patterns found on the side of the horse’s neck are described, -there is an apparent resemblance between them and those on the ventral -or under surface of the neck. The former were shown to be due to -natural forces, those of sustained and repeated underlying muscular -traction of muscles and jolting of the neck in locomotion; whereas -in this chapter a considerable number of patterns have been brought -forward and pictured on the under surface, and these are attributed to -artificial pressure from harness. The reasonable objection is raised, -“Why should the former be considered natural and the latter artificial -in their origin?” - -The answer to this is supplied by a consideration of the muscles shown -in the two contrasted regions. In Figs. 3, 4 and 5, the muscles of the -side of the neck are shown to be remarkably _strong and numerous_ (in -three layers), and _diverging in their directions_. In the muscles of -the under surface of the neck of the horse, see Fig. 12, the muscles -of the two sides shown are nearly parallel and no conflict of opposing -or diverging muscles can well take place in this “debateable land.” -If there were much divergent or opposing action going on it would, of -course, produce the effects on the hair towards the _upper_ part of the -neck, where the muscles tend to diverge more and more as they pass to -the head, and I have stated above that not a single instance in many -thousands of horses has been found above the level where a loose collar -ceases to rub when jolted upwards. This is very conclusive on the -matter of diverging or opposing muscular action. - -Then again the jolting in locomotion, which, in the case of the side of -the neck is probably more effectual in producing changes of hair than -even muscular traction, is almost absent from the under surfaces, as -can be learned from careful watching of the motion of a horse. - -Another reason which meets this objection very fully is that I have -shown that 300 cart horses presented 277 of their number with reversed -areas of patterns in the middle line of the under surface of the neck -and these thick-necked animals are just those in which the collar is -closely applied to the front of the neck in their heavy draught work, -thus rubbing almost incessantly against the lie of the hair. In the -thinner necks of the hackneys there are comparatively few indeed of the -patterns found here and their collars as a rule fit very loosely and -badly, and these frequently show a jolting up and down _clear of the -neck_, which is seldom if ever present in a well-formed cart horse. - -Further proof of this is shown by the simple fact that it is _under the -collar and within its range of movement_ that the changes of hair are -produced. - -No artificial pressure such as that of a collar is exerted on the -parts of the side of the neck where the patterns are found; so I would -submit that these two selected and much-disturbed areas owe their -hair-patterns to two wholly different forms of mechanical cause. - -I referred in the Preface to an important criticism of my earlier book -on _The Direction of Hair in Animals and Man_, and will now treat this -in some degree of detail. It is from the pen of an eminent American -biologist, then Miss Inez L. Whipple,[59] now Mrs. Wilder Harris, and -it is a careful, independent and thoughtful contribution from one who -by her studies in this field and in the study of the mammalian palm and -sole is widely known, and as widely respected. - - [59] _Science_, 23rd September, 1904. New York. - -Miss Whipple refers on page 403 to certain whorls and featherings on -the backs of the lion, ox, giraffe and larger antelopes, which I then -attributed to the action of the _panniculus carnosus_ in shaking off -flies. I am free to confess that the action then invoked by me was -inadequate and incorrect and the explanations now given of them in -Chapters X. and XI. on the ox and the lion, I think, are less open to -criticism. - -Again on page 404 she mentions the view formerly expressed as to the -cause of the reversal of hair on the chest of man. This, also, I have -reconsidered fully in Chapter XIII. where the action of the platysma -muscle is held to be the cause of that remarkable reversal. - -On page 403 the mistake I made in calling the reversed area over the -ischial tuberosity of the ischium in a dog a whorl is pointed out. This -is corrected in Chapter VI. on the Dogs. - -These three are the only errors of any importance that I acknowledge -at once. A certain number of minor points are questioned in the -Review, and the theoretical portion is strongly criticised. It would -be irrelevant to the main purpose of a book which is limited to the -subject of Habit and Hair Direction in Animals to introduce some of -the more debateable branches of the subject of the former book, such -as tufts, the direction of the hair on the mole, the classification of -the hair-streams of the mammalian body into primitive, those modified -by morphological change, and those due to use and habit. This last is a -very wide subject and is far beyond the present limits. - -I freely make another acknowledgment. The whole of the subject of the -Direction of Hair in Animals and Man was taken up _ad hoc_, that is to -say, for the purpose of testing the unpopular doctrine of Lamarckism. -If this be an offence against the highest spirit of science, I can but -accept the charge with a sigh, and go on, “faint yet pursuing.” There -is consolation in finding that increased study of a subject is bringing -order out of chaos, even if the field be small and the immediate crop -poor. - -The following are some of the objections raised to the theoretical part -of the book:-- - -The most serious charge against my interpretation of the mode of -formation of patterns (whorls and tufts) is that there is a lack of -harmony between my preliminary statement that whorls are due to motor -or muscular causes and a subsequent explanation of some of them as -due to external pressure. I did not state then as clearly as I do now -in many passages in the present chapters that for pattern production -there may be at least four causes: _friction_, _pressure_, _gravity_, -_underlying muscular traction_, and that whorls and featherings may, -of course, arise from some other external force acting on the hair -at the decisive point of struggle, just as well as from the more -common cause--muscular traction on the skin. I think in this region -of the Review and where she deals with Selection, she shows signs of -that scientific monism which is still affecting many of our great -biologists, that is to say, they desire a world-empire in evolution -for the great factor of Selection, and will stretch their arguments -considerably to save its face. This is shown in the Review on page 406 -where a very thin plea is put in on behalf of adaptation and Selection -in regard to hair-directions, as in man’s minute hairs, which cannot be -seriously maintained. That earth is stopped! - -Darwin’s open-minded dualism in this matter of the factors of evolution -appeals to me at any rate more than the jealous attitude of Weismann -and his eminent adherents. - -Miss Whipple is less determined than I am in claiming for Selection -the cause of the primitive slope of hair in mammals. It is the only -conceivable arrangement that could exist for the advantage of the -primitive forms in their simple life, and is, I submit, as much a -matter of adaptation to needs governed by Selection as the possession -of a dermal covering itself. - -One more point, which, I think, is a small one and a fair one to raise, -is worthy of a few remarks. Miss Whipple states that before variations -in hair-direction can be logically attributed to external forces -(giving the instance of the human scalp) “it should be shown that a -change in the direction of the external, more or less wiry portion -of the hair produces a change in the direction of the follicle.” As -it happens, this change is easily seen in the case of the reversed -hairs of the human forearm, if the hair be dark and the skin thin. -The essence of the theory that dragging on the skin by muscular -traction causes the hair to change its direction is that the relatively -important portion within the hair-pit is pulled here or there according -to the incidence of the prevailing force. But it is, to my mind, very -clear that much repeated friction or pressure or gravity acting on the -external and longer portion of the hair must, in course of time, drag -the portion buried in the skin with it and so change its direction. -These two portions of a hair cannot be arbitrarily separated. Shortly, -one may say that the push of a force is as evident as the pull. A -similar change in the direction of the buried part of a tree-trunk from -a prevailing wind can be traced. - -The last point is that I “omit to explain the mechanical process by -which divergent muscular action could affect hair-direction.” This is -well answered in the chapter on “Can muscular action in the individual -change the direction of the hair?” for there it is shown by numerous -examples in the human eyebrow that the muscles underneath the hairs -which are embedded in the true skin for a tangible depth, _do_ play -havoc with the normal arrangement of hair, as the conflict proceeds, -the resultant “pull” being actually engraved, signed and sealed by -physiological wrinkles of the forehead and face. - - - - -CHAPTER XVI. - -FIRST SUMMARY. - - -A large body of facts and an adequate proportion of reasoning have been -brought together in the preceding chapters. As far as I understand the -proceedings in a court of law, the business of arriving at results or, -as they are there called, verdicts, consists in collecting as many as -possible of the facts which bear on the case, these are sifted and -verified, or the reverse, a certain reasoning on them is carried on; -on this the verdict rests. This case before the court is of a civil, -not a criminal nature, and it is a claim made to a certain _derelict -property_, that is to say, the honour of forming patterns on the -hair of animals, claimed by Use and Habit. The facts concerned have -never been disputed, possibly because they were not thought worth the -trouble, but they have the singular merit of being open to almost any -educated person for confirmation or correction, and the reasoning is -certainly not profound, though I think it is cogent. In seeking a -result in such a cause, or verdict, one claimant might content himself -with an arrest of judgment, another that judgment should go by default, -and a third would claim proof. It is with the last I desire to stand. - -_In one word the claim is that of causation._ - -Now no one can deny that between the groups of phenomena, habits and -hair-patterns there is an evident relation; but the question may still -arise, “What is the link between them?” I have just said that the facts -are unquestioned; substantially they are unquestionable, and they are -open to the charge that they belong to the dust-heaps of science, that -they are, biologically speaking, such as used to engage the attention -of Nicodemus Boffin. Perhaps they are. Of course if they were just -collected haphazard and treated like a big collection of little shells -in a cabinet, without reference to their natural order, they would -possess no evidential value even if they were pretty, for so long as -a natural fact remains without its suited interpretation, so long it -belongs not to science. Hear Jevons: “Whatever is, is, and no natural -fact is unworthy of study for the purpose of its interpretation.”[60] -Hear also Sir E. Ray Lankester: “That only is entitled to the name -of science which can be described as knowledge of causes or knowledge -of the order of Nature.”[61] Fortified by the authority of a great -logician and a great biologist I proceed to claim proof of causation. -The stages of the case may be summed up as follows: - - 1. It has been shown that during the lifetime of an individual, - muscular action can change the direction of the hair. Chapter VIII. - - 2. Undesigned experiment has shown that changes in the direction of - the hair, mechanically produced in the individual, are sometimes - transmitted to the descendants. Chapter XV. - - 3. In all the selected examples adequate and ascertainable causes - have been demonstrated. - - 4. The changes of hair described, with hardly an exception, - cannot be conceived as resulting from the factors of organic - evolution--heredity, variation, adaptation and selection--indeed no - serious attempt has been made to connect them in any way with utility. - - [60] Jevons, _Principles of Science_, p. 269. - - [61] E. Ray Lankester. _Advancement of Science_, p. 7. - - -Causation. - -For my sins, the most obvious of which is that I made an unfortunate -choice of my first birthday, I had to learn up the dreary pages of -Mill’s _Logic_ and those of other philosophers, for the pleasure of -taking a medical degree, and was reduced to that orthodox state of -mind in which one was forbidden to suppose that, in the world around -where common men and women, every day and all day, are tracing causes -for the occurrences they see on every hand, there was anything at work -which could be truly called a cause. It was but natural to fall into -the nihilism of the Mill and Karl Pearson school. Having neither the -knowledge nor the hardihood to discern that their bewildering notions -of causation could be gainsaid, I had to remain submissive and as -much contented as possible with their views of an elusive subject. -This state of passive resistance was not relieved until I had the -great advantage of reading a valuable book by the late Dr. Mercier -on Causation, which seems to have let some fresh air into the musty -doctrines of the orthodox and autocratic philosophers. No one who has -read this work can doubt that after all there is such a process as -causation, and that to find a cause for events is not merely a pursuit -of the vulgar, but a duty of scientific persons. - -Mill appears to have given eighteen different accounts of causation -and to have contradicted himself over and over again in his works -dealing with this puzzle, devised mainly by Hume and himself; and his -successors, such as Dr. Mc’Taggart, the Hon. Bertrand Russell of “Dog -Fight” fame, Mr. Welton and Prof. Karl Pearson, have only got as far -as to reduce the number of his definitions and put his views into more -modern, but equally misleading terms. Without any disparagement of -their other claims to respect and admiration, one may venture to throw -overboard this school of philosophers when considering causation, and -one may walk and talk in a clearer atmosphere. - -The subjects here considered are cause, effect, result, reason, -evidence and proof, and all can be seen to enter into my small thesis. -They may then be defined, according to Dr. Mercier, as follows:-- - - 1. A cause is an action, or cessation of action, connected with a - sequent change or accompanying unchange, in the thing acted on, or - more shortly for my purpose _a cause is an action upon a thing_. - - 2. An effect is a change connected with a preceding action. - - 3. In reference to causation a reason means the cause of an unchange. - - 4. A result is the changed state that is left when an effect has been - produced. - - 5. Evidence is of three kinds: evidence of sense, evidence of reason - and evidence of hearsay. - - 6. Proof is evidence inconsistent with an alternative to the - assertion. - -I turn now to the aid given to the case before the jury, and must show -how Dr. Mercier’s definitions establish it. - -The cause of the changes described is the action of certain new habits -on a living growing structure of the mammalian body. - -The effect is the change connected with the preceding change of habit. - -The result is the changed direction of hair, in other words, new -patterns, left when the new habits have been produced, and have been -long enough in operation. - -The reason for the unchanges observed in many instances is the -primitive force of the normal direction of growth of the hair. - -The proof of the thesis is that the changes described in the hair--the -evidence--is inconsistent with an alternative assertion. - - -To Some Critics. - -It may save time and trouble if replies are given in anticipation -to certain classes of critics. I refer of course to those who are -well-informed in their branch of knowledge. - -To those of high authority and learning, those who ride on white asses -and that sit in judgment, who may seek to throw the case into chancery, -saying, “This will never do, it contradicts current biological -opinion.” I can only meekly reply that current or orthodox opinion -is frequently wrong, or (shall I say) seldom right, and that the -history of human thought is strewn with examples which may justify my -impertinent reply. - -To another who says, “I daresay you are right in your claim, but there -are too many metaphors,” I would suggest that, so long as metaphors are -not used as arguments, the more metaphors--within limits--the clearer -the meaning of the statement. - -To him who grudgingly allows, “I think you have proved your case--but -what does it prove?” I reply that it proves what it set out to prove, -no more and no less, and it is an integral part of proof of a larger -claim. And if he further grumble that these matters have no interest -for him, one may ask him to live and let live. “What have I now done in -comparison of you, is not the gleaning of your grapes of great Ephraim -better than the vintage of this little Abiezer?” - -To the man who reads the preface and the headings of the chapters, -glances at the illustrations, detects one split infinitive, two -misspellings and three errors of punctuation, goes home to tea and -writes his opinion--it may suffice to remind him of “that curious -mental state which looks past problems without seeing them.” - -I will conclude this section with a parable. - -In the year 1788 Arthur Young in his travels through France visited the -desolate region of the Landes. “Wastes, wastes, wastes!” was his lament -over neglected Brittany, and no less could he say of the Landes, at -that time a miserable tract of low ground, bordering the Bay of Biscay. -Plantations, the sinking of wells, drainage and irrigation began to fix -the unstable sands, making fruitful the marsh, creating a healthful -climate and a fertile soil. Early in the 19th century the land here -was sold _au son de la voix_, that is to say, the accepted standard -of measurement was _the compass of the human lungs_. The stretch of -ground reached by a man’s voice sold for a few francs. Crops replaced -the scanty herbage of the salt marsh, and a familiar characteristic of -the landscape, the shepherd on stilts, was seen no more. Six hundred -thousand hectares of Landes planted with sea pines produced resin to -the annual value of fifteen million francs, and through these trees -also was achieved a climatic revolution, and it is this district which -is now a department of a great and well-ordered State.[62] - - [62] From Arthur Young’s _Travels in France during the years_ 1788, - 1789, with introduction by M. Betham Edwards. - - - - -CHAPTER XVII. - -VARIETIES OF EPIDERMIS. - - -Passing now to the smaller trenches of the front line I have chosen as -the first of them a small study of the varieties of epidermis found -in mammals. With the exception of aquatic mammals so few of this, the -greatest vertebrate class, are not clothed with hair that it is only -on the comparatively hairless body of man, with its third of a million -fine hairs, that the varieties of epidermis can be broadly studied. -Much of this chapter will resolve itself into a consideration of the -palmar and plantar surfaces of certain mammals, where no hairy covering -obscures the operation of stimulus and response. - -I assume that the foregoing phenomena of hair-direction have chosen -and raised on his shield their own king. But here I must ask of the -succeeding groups when they say, “I am, Sir, under the King, in some -authority,” the question, “Under which King, Bezonian, speak or die”-- - - Shall it be Darwin’s Personal Selection? - Roux’s Cellular or Histonal Selection? - Wallace’s and Romanes’ Sexual Selection? - Weismann’s Germinal Selection? - The rule of Mendel? - Selection of mutations according to de Vries? - Or shall it be the barbarian king _Plasto-diēthēsis_? - -Which indeed of the seven kings will they choose, if I may thus -personify them? I may, perhaps, urge on them the mild and tolerant -rule of Lamarck and Darwin rather than that of the other anointed -sovereigns, hoping this cannot be taken as an attempt to influence the -jury through the Press in a case which is still _sub judice_. - - -Stimuli and Response. - -The skin over the trunk and limbs of man is exposed to stimuli of -pressure, friction, heat, cold and wind in very different degrees, -according to the part which it covers. I do not here refer to nocuous, -or so-called noci-cipient stimuli, as being too casual in their -incidence for the question in hand. Broadly the ventral surface of -the neck and trunk differ much, in respect of the qualities of their -epidermis, from the dorsal. The skin over the former is softer, thinner -and more flexible than the latter, which is in adult life thick, hard -and with larger openings of the sebaceous glands. As the two main -layers of the skin are so closely united it is impossible to state -any general rule as to the parts played in this manufacture by the -epidermis and dermis respectively. Altogether the skin from the dorsal -surfaces of mammals provides a much denser fabric than the latter, and -different qualities of leather are obtained from different regions. -Corresponding differences of texture are found on the extensor and -flexor surfaces of the limbs, especially on the hands and feet. In the -course of his long evolution from a hairy stock, whether simian as we -thought yesterday, or a lower one as Professor Woods Jones suggests -to-day, these dorsal surfaces of neck, trunk and extensor surfaces of -limbs have been exposed through countless generations of men to vastly -more stimuli of friction, pressure, and response, than those of the -ventral and flexor regions. As man’s hairy covering diminished, through -some mysterious and at present unrecognised cause, these stimuli became -increasingly potent in producing a tissue denser than that of the more -protected ventral parts where all forms of these stimuli are slight. I -do not claim that this was a phenomenon that began with man, for in a -measure it was present in those forms which preceded him, and in many -related mammals under the cover of their hairy covering. - -When we remember, or conceive what a large portion of each of his -24-hours even in his earliest form throughout life man must have spent, -as he still does, in lying on his back or sides, and in sitting with -his back against a supporting object, and with his gluteal and ischial -regions pressed hard against whatever seat he has selected in cave -or drawing-room, we need not travel far in thought to understand how -great has been the preponderance of stimuli from friction and pressure -on the dorsal and extensor surfaces over those on the ventral and -flexor--and here comes in our familiar “total experience” with stimulus -and response spread over a vast stretch of time. It must be borne in -mind that from the facts of the case a very large number of individual -men and women were exposed to similar, but not the same stimuli at each -stage of the process involved. It is matter of common knowledge that -not only on the palm and sole of man, but on regions where the skin -is not specialised in that remarkable manner that is found in those -regions, but also in others, that increased pressure and friction will -very soon cause a harder and thicker growth of epidermis, as on the -skin over a projecting bone in club-foot, over the shoulder where a -weight is constantly carried, on the knuckles of many manual workers, -and over the patellæ of a devout Roman Catholic, as I have often seen. - -On the other hand what conditions more calculated to thin and soften -the skin could exist than those operating on the ventral and flexor -surfaces, axillæ, groins, external genitals and the bends of the elbow -and knee-joints, where pressure, with little friction and greater -warmth and moisture prevails? I need do no more than ask which is the -more reasonable of the two forthcoming explanations of such phenomena, -on the one hand that they are adapted _for_, and on the other adapted -_by_ this experience? I doubt if at any stage of the long process -this slow manufacture of differing fabrics ever conferred on man any -survival value or better matrimonial prospects. At any period or stage -which I have supposed it can only be claimed for the results on the -skin that they did _not_ cause the animal to pass through the meshes of -the sieve, and theoretically might be classed among the _indifferent_ -modifications, even if they added a little to the comfort of their -possessor. - - -Skin of Palm and Sole. - -One can examine in more detail the remarkable form of skin which is -found to cover the palmar and plantar surfaces in many mammals. It is -highly specialised and appears in many degrees of efficiency for the -purposes, or uses, of walking and climbing, grasping and discrimination -of objects. With two or three insignificant exceptions these are the -only regions even of man’s body where hairs do not grow in the normal -state, and in most other mammals hair is absent from the component -parts or pads, which correspond to our palms and soles. In the absence -of hairs and sebaceous glands and the presence of as many as 320 -sweat-glands to the square centimetre, and especially the papillary -ridges, the mammalian hand and foot present a fruitful field for study. -They have been studied by none more earnestly and thoroughly than Dr. -H. Wilder Harris and Mrs. Wilder Harris (_née_ Inez Whipple). This -small area of skin as an organ for grasping and discrimination has -been studied by persons from different, but not conflicting points of -view. Time would fail me even to mention these, but I would recall -here one aspect of the matter, that is the name given to it by these -eminent authorities, Friction Skin. I think I do them no injustice, nay -even honour, when I claim them as allies for us “Old Contemptibles” -in the struggle, Lamarck _v._ Darwin in respect of these characters -of the “mammalian chiridium.” This is a term employed by them for the -hand and foot of all mammals, and is very convenient for descriptive -purposes. From this point of view this organ has been produced from -more generalised ancestral structures by reason of friction and -pressure, and not for the purpose of resisting them, at least in their -initial stages--again, adapted _by_ and not adapted _for_ meeting those -forces. There are other views of the matter held by Pan-Selectionists, -notably that of Dr. Hepburn, in regard to the papillary ridges. He -would, as I gather, treat them as primarily induced, by selection, for -the better grasping of objects cylindrical or more or less globular. -I have referred elsewhere[63] at some length to this in a book -describing the examination of the hands and feet of eighty-six species -of mammals. The varieties of epidermis were divided into the smooth, -corrugated, scaly, nodular, hairy, rod-like and ridge-covered forms, -also four mixed varieties, such as corrugated with coarse transverse -ridges on the digits, corrugated with papillary ridges, nodular with -papillary ridges, and hairy with coarse transverse ridges and smooth -pads. Of these the species with smooth epidermis and hair are few and -unimportant, and the largest group examined was that of the Primates, -thirty in all, in which papillary ridges were always present. It is -highly probable that the causes of these modifications of the epidermis -in diverse groups of animals could be traced to the habits and modes of -life of each, but I make no attempt here to do this. It is also matter -for inquiry, upon which no agreement has apparently been reached, how -it came to pass that man has virtually lost his hairy coat, and in -regard to the palms and soles of animals, what may be the reason that -so few have any hair on them, and why man has no sebaceous glands, but -has very numerous sweat-glands in these regions. - - [63] _The Sense of Touch in Mammals and Birds._ A. & C. Black, 1907. - -This is all of great interest, and possibly some day the Mendelians -will solve for us the mysteries thereof. But here I need only ask how -it would have been possible for hairs to grow, or, if growing, not -to be promptly worn away on a surface used by animals from monotreme -to man for walking-pads, and by most of them also for grasping and -discrimination between objects as well. We are so familiar with the -thickening of the skin on the hands of manual workers and on the feet -of those who walk much, to say nothing of what we call a “corn,” from -pressure of tight boots, that we are in danger of forgetting that the -protecting skin over the hands and feet of animals was of necessity -adjusted in a crude way to the measure and kind of walking in past ages -and in all levels of life, and that it is maintained in that adjusted -condition by the use, or disuse, of each life. Another familiar example -is that of knee-pads, as in the gnu and other ungulates. Some such -process it is legitimate to assume whether it be reckoned backwards -to monotremes or later levels of life-forms. We see then before our -eyes how this living tissue becomes adapted in varied ways by response -to the stimuli of friction and pressure, and the modifications thus -slowly effected must, one would suppose, be transmitted to offspring -ultimately from the original groups with which the process began, -when by frequent repetition small changes of structure have arisen at -last. I acknowledge the limited force of the answer, that this picture -involves the continuance in each succeeding generation of the stimuli -which initiated the changes, but the fact remains that _ex hypothesi_ -the changes are there, written in tablets of animal tissue, and that -the making-up of an organism in course of many ages is not and cannot -be conceived as being governed alone by the “tyranny,” even in the -_good_ Greek sense of that word, of rigid unit-characters. - -In the assumed process the correcting force of the Lamarckian -drill-sergeant is always at hand, as it superintends the construction -of tissues and parts, and I doubt if even Professor Thomson will here -interpose the difficulty of “correlation with useful characters,” -for the only important functions which are invoked as the invariable -antecedent of these structures are the elementary habits of walking, -climbing or grasping objects in certain different ways, and without -these habits or functions there would be neither lemur, monkey nor -man to interest the mind of a biologist from Mars. As I am desirous -of condensing such replies as I can make to certain opinions of -opponents and objections, I will remind the reader that Professor -Bateson in the _Jubilee Volume_ of 1909, pp. 100, 101, uses a metaphor -to illustrate his view that among the facts of nature we meet certain -definite structures and patterns in which we ought not, if desiring -rightly to interpret them, to expect to find _purposefulness_. He says: -“Such things are, as often as not, I suspect rather of the nature of -tool-marks, mere incidents of manufacture, benefiting their possessor -not more than the wire-marks in a sheet of paper, or the ribbing on the -bottom of an oriental plate renders these objects more attractive in -our eyes.” Metaphors are both indispensable and delightful, they are -the very salt of scientific and other sober writings, but they have a -rather “slim” way of betraying their employers. They express at times -the truth too well, and at others when vague and inaccurate lead the -reader right astray. Thinking of this metaphor of tool marks I was in a -modern church the other day and saw just before me a stone pillar the -pediment of which was marked with oblique parallel marks of a mason’s -tool. Here then there were marks left by a human hand at some date or -other and by means of some tool or other. I know one may not reason by -an analogy from inorganic to organic phenomena in which the push and -force of life is in full blast, and that inheritance in the former is -ruled out; but, taking the metaphor seriously, you have to account for -the appearance of the ribbing of paper and the mason’s marks on the -stone. To call them “by-products” or “tool marks” or _obiter facta_, -or by any suggestive name, does not advance the reply to the question, -“Whence came this great multitude?” If I were unwary enough to be here -trying to attack Selection and to respond to the invitation of the more -learned arachnida to walk into his parlour with a scheme of organic -evolution for him to demolish at his leisure, I should have to enter -upon the question of adaptation, specific difference and perhaps other -great disputed doctrines. But, knowing my own limits, and desiring to -keep to the self-imposed limits of the title of this book, I again -plead that I am here contending, as all through it, for the origin -of initial modifications by use and habit, and for nothing else. No -one who reads of the immense amount of research and learning that are -being carried on by the students of Mendelism and Mutationism can fail -to admire them. But, as I have remarked before, these are systems of -thought which in the main deal with characters by distribution or -“unpacking,” as it is called. Such a process of course leads to new -characters by amphimixis, and no one of whom I know denies it. Such -work is concerned with fresh views of the origin of species, but with -lamentable cowardice, or humility, I leave all that great sphere to -those who are incomparably more fit for it, and just seek to mind my -own business. - -In subsequent chapters on modifications and their origin I shall not -need to repeat these observations. - - -Some Chosen Examples of Palms and Soles. - -The facts then of a few selected examples of the palms and soles of -mammals are shortly these. - -A heavy, burrowing animal, the _earth wolf_ of the Cape, has a very -smooth, hard epidermis covering its foot-pads and is thus a generalised -structure which I have found in no other animal. - -The common _mole_ which uses its broad strong fore-feet like a pair -of spades, and depends chiefly for discrimination of its habitat on -the delicate sensory nerve-endings of its snout, has a hard nodular -skin which is much less developed on the hind feet than the fore feet, -the latter being less active tools. It has no papillary ridges, in -accordance with this fact, and is a very efficient miner that never -practises ca’ canny, as we know to our cost when we go out in the -morning and find great heaps of soft earth thrown up in the line of its -advance from its base or fortress. Such a mode of life lends itself -remarkably to the kind of skin on its feet, and this is _now_ at any -rate adapted _to_ its environment. - -The _capybara_ is a large, heavily-built rodent, and has rather a -smooth epidermis not specially thick, with long and efficient papillæ -of the corium shown in microscopical sections. Being largely aquatic in -its habitat, and given to frequenting marshy ground and to enjoying as -much sleep as it can manage, it depends a good deal for discrimination -of objects on its sensitive corium, and its epidermis is not much -specialised for, or by friction and pressure in walking. It does not -acquire by reason of stimuli and response any unnecessary tools. - -With this may be classed the _echidna_ or Australian ant-eater which -has sparse hairs set on a hard and slightly corrugated epidermis, and, -being mainly a nocturnal animal and living a secluded life, it does not -walk much or far in its stealthy pursuit of worms and insects, and the -stimuli of friction or pressure encountered by it are few. - -A similar condition is found on the feet of many small carnivores. - -Animals with scales on their feet, which are held to constitute the -earliest stage of the Primate modification of papillary ridges are such -as the _potoroo_, _wallaby_, _kangaroo_ and _giant ant-eater_. Such -scales register a long, long series of stimuli of friction and pressure -in these and their ancestors, in a level of life before any delicate -discrimination of surfaces came into operation. - -The nodular form of skin is present in the Canadian _tree porcupine_, -where rough nodules cluster closely on the surface of both feet, and -it is a significant fact that it shares with the American _opossum_ -the peculiarity of nodules on the ventral surface of the powerful -prehensile tail. This adaptation tends to efficiency in its arboreal -life, and may well have been produced by infinitely small degrees of -response in structure in the course of a long evolution. - -The _rabbit_ alone have I found with rod-like projections of the -epidermic cells, among which are set in dense order the soft, long, -delicate hairs and which thus conduce to its wonderful power of -treading on sharp objects without injury. We thus see the inner meaning -of dear old Brer Rabbit’s jeer of triumph to Brer Fox, “Born and bred -in a brier bush.” This adaptation might be an unit-character segregated -from the ancestral stock of the Leporidæ, or it might not, but at any -rate the rabbit leads a life in which its walking or running is no -more prominent or frequent than is a good “run” on the part of a hunter -which pursues the hare with his beagles, and one may say at least -this--that its mode of life has _not_ produced a hard rough nodular -surface on its feet by stimuli of pressure and friction and response. - -One may observe that there’s a divinity doth shape our ends, rough -hew them as we may, even if some objection be taken to the present -view of rough-hewing of parts of our organism on the ground of its -piecemeal character, rather than dealing with the organism as a whole. -To which it may be replied that the Mendelians give high support to the -piecemeal study of the profound subject of genetics, and further that -the business here is to look separately and simply at a few selected -attributes of parts of an organism, and see how they _began_ to grow -big enough to avoid passing through the meshes of the sieve. - -The foregoing examples of animals in which papillary ridges are absent -have been given not in their zoological order, nor as representative -of a great many groups, but as taken from the eighty-six species I -examined myself. The following belong to the same series, but all -present papillary ridges in an ascending scale towards perfection in -man. - - -Examples of Ridge-covered Palms and Soles. - -The common _hedgehog_ though a burrowing animal like the _mole_ is -not always underground as his distant relative is. He is not always -mining and though of ancient lineage he is a “slacker” compared with -the mole, hibernating for months, and spending also much time in his -nest and prowling slowly about above ground for insects. He has thus -acquired his somewhat indifferent epidermis that one finds, but with -the addition of sparse papillary ridges. It is the species among this -list with the fewest of these tactile structures, for there are but -three or four separate ridges on six of the ten digits, and radiating -groups on only three of all the palmar and plantar pads. So _quâ_ touch -it is ill-equipped, though it has adapted a higher form of tool than -the rabbit. - -The common _squirrel_, that sits much and walks mainly on branches -of trees just as much as it needs to do, has an epidermis little -differentiated, and one which is corrugated with scanty papillary -ridges on the palmar and plantar pads, and none on the digits. - -The _squirrel-like phalanger_ which flies always more or less downwards -by a kind of parachute-arrangement has most of its palmar and plantar -skin covered with papillary ridges encroaching upon its corrugated -areas, and a response to more delicate tactile experience has been thus -produced by its intermittent performance of ordinary progression. - -_Azara’s opossum_ presents about as large a part of the surface covered -with nodules as with papillary ridges, the latter highly-developed for -an animal so low, zoologically-speaking, but one in which delicate -discrimination is much practised. - -The _kinkajou_, another arboreal animal which walks about on trees more -than it uses its feet for prehension, trusting much to its prehensile -tail, shows its corrugated epidermis and papillary ridges developed in -about equal proportions. - -These five mammals thus show that the stimuli of pressure and friction -and the response to them are being complicated by the addition of the -more delicate tactile organs known as papillary ridges, and these, -perhaps, in a secondary way are becoming useful in preventing friction. -But I must not omit to point out that, _quâ_ prevention of slipping, -the few sparse papillary ridges of the _hedgehog_, _squirrel_, -_kinkajou_ and _flying-phalanger_, especially those on the extreme tips -of the digits, could have no effect in this prevention and no survival -value. It is otherwise when they are developed in large areas as in the -succeeding groups. - - -Primates. - -All the thirty species of Primates possessed papillary ridges to such -an extent that only small areas of the palmar and plantar skin of the -lemurs showed any other than these remarkable characters. It is so much -a property of the Primate hand and foot to possess these that it might -be almost made a matter of ordinal rank belonging to the Primates, were -it not that a few stray lower mammals also possess it. - -The _black-headed lemur_ is the lowest Primate examined and it is -characterised by highly developed patterns of ridges on the palm -and sole, and these are interspersed with nodules on the regions -less exposed to pressure. The complexity of the patterns of another, -the _ring-tailed lemur_, is greater still. Now these nodules are -distinguished from the rough undifferentiated nodules of lower forms, -such as the Canadian _tree-porcupine_, and from the scales in others. -When examined with a lens the separate nodules show small groups of -papillary ridges two, three or four on each nodule, arranged in a -direction parallel to those of neighbouring nodules. They are in fact -papillary ridges in embryo, and shortly above this lemur-stage in -the ascent of animal life they are merged into papillary ridges in -patterns. All this is well told at length by Dr. and Mrs. H. Wilder -Harris. I refer to it here because the disappearance of the rough, -plain, nodular or corrugated epidermis in mammals is coincident with -increasing activity and intelligence in forms who employ or acquire -a more delicate sense of touch in their hands and feet. The cruder -response of structure to stimuli of friction and pressure, evident in -the lower forms, is abandoned in the higher, as tactile delicacy in -prehension comes more into play. Here, for example, may be a subtle -case of the co-operation of the mould and sieve in action. - -From this lemur-level the degree of development in the Primate palm and -sole rises and falls, but always advances through the _lemuroidea_, -_monkeys_ and _anthropoid apes_ to man. No attempt at the tracing of -the lineage is made here, and from the present limited point of view -little remains to be said about different Primates. Only two of those -examined will be briefly referred to, the _slow loris_ and man. - -The _slow loris_ shares with many monkeys and apes a very soft moist -skin of the palm and sole, and in this and other refinements of this -region it is much beyond many more intelligent, active and higher -Primates. I have never had social intercourse with a _loris_, but -I have shaken the friendly little hand of a _chimpanzee_ with a -combination of pleasure, mild shock and perhaps memories of my own -palms in the more nervous moments of early life. It is a strange, -cool, soft and damp surface, but the sensation conveyed by the skin -of a _loris_ lately dead show that in life it is a wonderfully -sensitive and tender structure. The whole of the palm and sole is -covered with well-developed patterns of papillary ridges especially -on the palmar and plantar pads. No trace of old-fashioned nodules, -scales or corrugation is to be found. The structures due to stimuli -of friction and pressure in its ancestors have disappeared for ever -from this specialised and small group, and we may fairly hold, in -accordance with the law of conservation of energy, that the past is -somehow enwrapped in the present in the strange hands and feet of -the _loris_. The adaptations of the hand and foot of the _loris_ are -most obviously now of value to it in its wary and dangerous life in -the branches of trees, but are equally unfitted for that higher life -which, in his case, consists in going lower down, on the ground. The -extraordinary deliberate life of the _loris_ has been often described. -As he moves from place to place on a branch, fixing one limb before he -moves another, much as we do in going up a ladder, he is subjected much -to the stimuli of pressure, but hardly at all to those of friction. -He sets us a good example of leaving nothing to chance. Thus his soft -sensitive skin suits well his mode of progression, but he would find -the harder, rougher skin of an African baboon very inferior for the -purpose. Here, indeed, I have ventured on the edge of Tom Tiddler’s -ground, and the Pan-Selectionist or Mendelian will make a grab at me -so that I escape with just the loss of a portion of clothing. After -escaping I have only to observe to him as to the adaptations of a -_loris’s_ hand and foot that in human life, of which we know a little, -one can in a measure forecast what a man will be like if we are told -on reliable authority what he and his ancestors have _not_ done in the -way of muscular or cerebral output, without information as to what he -has done. This is too obvious, but also too complex to prove here by -numerous illustrations and it may be left as a mere suggestion as to -the past life of the _loris_ and his ancestors for many generations. He -has _not_ walked in the ordinary method of terrestrial mammals, he has -always moved very slowly about the branches of trees, he sleeps most -of the day in a hollow of a tree, curled up like a ball, and his home -is in moist, tropical regions. No habits and conditions of life could -be better calculated to soften and moisten the skin over his palms and -soles or expose it less to stimuli of friction, while even those of -pressure in his tenacious grasp of boughs are decidedly intermittent. -Unless one may assume the appearance in the distant past of some -unit-character of soft, moist skin in this and other Primates, it seems -difficult to refuse the Lamarckian claim of long, long absence of -effectual stimuli of friction and equally long presence of enervating -“negative” conditions. Proof of such a view is, of course, wanting. - - -Palm and Sole of Man. - -The palm of man’s hand is a miracle of adaptations for touch and -grasping, but has lost most of the coarse structure formed in response -to stimuli of pressure and friction which we saw were common in lower -mammals. This indeed he shares with most simian forms. The skin of -our hands is now very much what we make it and responds very soon to -fresh positive or passive conditions. The horny, cracked epidermis on -palm and digit of the old sailor may be contrasted with the soft and -flexible and pale surface of his twin-brother, the bank clerk, who is -of studious habits and has neither the vice of gardening nor golf. If -one compares the hand of the ordinary maid with that of her mistress -the difference is striking. But if one compares the hand of that -mistress with that of her spinster sister who has lain for twenty years -in bed or on a couch, the difference is equally significant. Indeed the -sofa-and-bed-ridden invalid, of whom I knew a few once, but who have -gone out of fashion, gives the observer some useful thoughts as to the -why and wherefore of the strange skin of the hands of the _slow loris_ -previously referred to. And if he be disposed also to the pleasant -pursuit of moralizing at the expense of others he will feel led to -reflect over harshly on the invalid and compare her outlook on life -with that of the _loris_. Even in this concrete case of the hand of an -invalid there may be evidence of positive as well as negative response, -if one examines the right forefinger so much used in sewing, where the -skin becomes hard and thick. - -The foot of man has a good deal of negative evidence in favour of my -contention as well as positive. As to the latter, in the thickening of -the skin over the heel and ball of the great toe in those who walk much -we find changes precisely similar to those on the hand. The negative -or degenerative changes visible on man’s foot consist chiefly in the -remarkable simplicity of pattern of the papillary ridges as well as -their flattening and blurring, through wasting of those which occupy -mainly the arch of the foot. These will be shown in the next chapter -in a drawing. When this portion of skin is compared with that of the -foot of any monkey or anthropoid ape it is clear that in this respect -the skin of man’s foot has undergone even more degeneration than his -hand has shown of higher development. This degeneration has coincided -with two facts, first that man’s terrestrial locomotion has advanced -far beyond that of any other Primate, and second, that he alone has a -plantar arch. This subject belongs to a later chapter and is referred -to here because the possession of an arch to his foot has caused man to -escape, on the under surface of it, a vast proportion of the stimuli of -pressure and friction involved in his mode of walking, and the extreme -simplicity of his plantar papillary ridges, and relatively thin, soft -skin under the plantar arches affords a fairly conclusive example of -change of structure from disuse _per se_. - -I have thus only selected and used two striking types of the Primates, -the _loris_ and man, not wishing to burden this part of the subject -unduly with intervening and less characteristic forms of life. It -may be legitimate here to say in defence of this long chapter that -it illustrates what I desire to keep before me all through, the fact -that use, habit, environment and selection go ever hand in hand. In -all matters of science one has to descend to particulars, so it seemed -necessary to select a few scattered phenomena in the best known groups -of higher animals and endeavour to understand how certain “characters” -or better “modifications” _began_ to grow big enough to avoid passing -through the meshes of the sieve. - - - - -CHAPTER XVIII. - -ARRANGEMENT OF THE PAPILLARY RIDGES. - - -The subjects of the preceding, present, and the succeeding chapter -are closely allied, from the fact that they all deal with structural -changes in the mammalian skin, and that most of these are exhibited for -us on our own palms and soles. They certainly comply with the canons of -Henri Poincaré as to simplicity, regularity and chance of recurring. - -In the last chapter, papillary ridges as organs of touch were briefly -referred to, but their mode of development into complicated patterns do -not concern the questions here at issue. The general manner in which -they are arranged on the hands and feet of man and the Primates below -him is very much a matter for such Lamarckian methods of inquiry as I -have chosen. In this examination of the ridges I will proceed from man -backwards among the Primates and lower still. I described these ridges, -in a book previously referred to in the following words, and find no -need to alter them here. “The ridges and adjoining furrows which cover -the palmar and plantar surfaces of all Primates and a few lower forms -in smaller degree, may be compared to the ridges of a ploughed field -over which some object, as a light roller, has been passed, the effect -of this being to produce a series of ridges with flattened tops. This -can be well seen with a lens when the ridges are examined in profile, -and is their normal condition in man and many lower animals, in nearly -all the palmar, plantar and digital regions.”[64] The reservation in -the last sentence is not material here. - - [64] _Sense of Touch in Mammals and Birds._ - - -The Hand of Man. - -[Illustration: Fig. 59.--W. K. Right hand drawing of papillary ridges, -made from impressions.] - -Beginning with the tips of man’s fingers and excluding the wonderful -patterns which Galton did so much to elucidate and bring into order, -we find the ridges are placed, to a remarkable extent, parallel with -the skin-flexures which will be treated in the next chapter. I term the -thumb and fingers D 1, 2, 3, 4, 5 for the sake of accuracy (Fig. 59). -Over the last joints (distal) of all the digits the ridges suddenly -diverge from their directions in the patterns of the pulps, and become -arranged transversely to the axis of the digits. This arrangement -is observed on the remaining segments of the digits except, very -significantly, on the outer or radial side of D 2 and the inner or -ulnar side of D 5 where they slope more or less towards the palm. Their -lines thus cross slightly those of the skin-flexures in these small -areas. On the radial side of D 1 this slope appears in a minor degree, -but here it coincides with those of the flexures. On the palm are -similar arrangements of the ridges near the radial and ulnar borders, -and especially on the two great eminences, thenar and hypothenar, -also at the bases of digits 2, 3, 4 and 5. Over the rest of the palm -they are arranged in a longitudinal or oblique direction. These brief -descriptions are enough to show the close correspondence of the -arrangement of the ridges with the flexion of the numerous joints of -the hand. An observer can demonstrate this by holding up the open hand -in a good light and flexing the fingers slightly, which brings nearly -all the ridges adjacent to the joints into directions parallel with one -another, the greater lengths of D 3 and 4, and their closer functional -connection with one another, producing thus a transverse arrangement, -and in D 1, 2 and 5 a more oblique one. In the palm this correspondence -of ridges with flexion lines of joints is not found so much except in -the central part of this surface. But the oblique and longitudinal -ridges of the palm where it becomes concave in the action of folding -the hand over a globular object are well shown there also to correspond -with such action. - -This general grouping of ridges is seen, _mutatis mutandis_, to belong -to all the palms and soles of lower Primates, and the illustrations -given will speak for themselves, so that little need be said on each. - - -Reasons for Arrangement Observed. - -When one discusses the forces in action on man’s hand which are claimed -to have thus arranged the ridges, in regard to the question of use and -habit, little more need be added as to those of other Primates, and it -is because we know more about ourselves than them, and our own palms -and soles are available for inspection, that I have taken man as the -example. - -The main question is the old and now familiar one: “Are these ridges -arranged as we see them _by_ use and habit, or adapted _for_ use?” -Dr. Hepburn and the orthodox Selectionist would say that, of course, -their mode of arrangement is an adaptation governed by selection for -preventing slipping in the action of grasping an object by the hand, -and in the foot for preventing slipping in walking. This does not take -into account the question as to how the original slight shifting of the -ridges in the earliest man and in lower forms could have had selective -or survival value, for example, the insignificant sparse groups of -ridges on the palm, sole and _tips_ of the digits in a hedgehog or -squirrel. As things are now they _do_ subserve these purposes. But I -think this matter of prevention of slipping has been much exaggerated, -though I may be told that this is a matter of opinion and not a valid -argument against the hypothesis. - - -Foot of Man. - -[Illustration: Fig. 60 S. K. Right foot drawing of papillary ridges -made from impression.] - -The point may be best understood by considering the foot of man, of -which Fig. 60 shows a good example. The value of the roughened surface -of the foot with its papillary ridges can hardly have been great, even -in the days when man’s foot was naked, at any rate so little that for -him to acquire by a selectional process such a remarkable _change_ of -arrangement as we see when we look at the foot of man and of any other -Primate involves on our part a tremendous stretch of imagination as to -its _modus operandi_. These low, soft ridges of man’s foot could do -little to prevent him from slipping on such surfaces as grass, sand, -rock, wet or dry, and from the time when he began to protect his feet -with coverings this small value would be further reduced. _Underneath -his developing plantar arch it would not exist at all, and yet here -especially he has changed their direction._ As to the papillary -ridges, man’s foot has sadly embarked on the pathway of degeneration -much as his little toe has done. Not only has he here a much simpler -arrangement than any ape or monkey, but the individual ridges are -blurred and flattened on much of the plantar surface. This comes of -his pride in acquiring his human distinction, or title of nobility, of -a plantar arch and his coincident increase of pedestrian locomotion. -On the triple bases of support, heel, ball of great and little toe, -the ridges are still strongly marked and coarse; transverse on the -heel, whorl-like on the ball of the great toe, and oblique or nearly -transverse on that of the little toe. On the rest of the surface they -are vulgarly transverse. And I may add that the toe-prints of man are -simplicity itself compared with his finger-prints. It would seem that -this example of arrangement of ridges on man’s foot is strongly in -favour of the hypothesis that they are so disposed by flexion of the -foot in walking, and not by some need for prevention of slipping under -the guidance of selection. - - -Lower Animals. - -[Illustration: Fig. 61.--Slow loris--right foot.] - -At the other end of the scale the scanty ridges of a hedgehog’s or -squirrel’s foot would be negligible in preventing slipping, however -useful they would be, as I hold, as early organs of touch. Between -these extremes the _slow loris_ affords a valuable example to study, -with the help of Fig. 61. The foot, as more concerned with prevention -of slipping than the hand, is chosen for observation, but with little -exception the hand agrees closely with it. On the tips of four digits, -D 1, 3, 4 and 5, omitting D 2 for the moment, the ridges are arranged -nearly in a longitudinal direction, and would on that account have -little or no effect in preventing slipping of the foot. If this be -disputed one can but reply that if the need of preventing slipping -in this tiny area were to call forth selective value this is not the -arrangement of the ridges that best serves the purpose. It may be -remarked here that the pulps of _lemurs_, the _marmoset_ and _squirrel -monkey_ all show this indifferent mode of grouping of ridges. The -aborted D 2 of the _loris_, with its hooked nail overhanging the -circular pattern of ridges, is obviously quite unadapted for any -non-slipping effect of its skin, as a glance at the figure shows. On -the remaining segments of the digits the ridges in the main slope from -each side of each digit in the distal direction and fail here also to -obtain the best, or transverse direction for preventing slipping in -locomotion. The corresponding surface of D 1 is not different from its -pulp as to direction of ridges, and it is here to be noted and admitted -that when this muscular great toe is tightly applied to a branch, -which from its shape it must cross at a right angle, the non-slipping -effect of the longitudinal ridges would be very effective. One must -then notice that over the middle of the sole of this foot the ridges -have again changed their direction and lie in a transverse direction. -Between this and the basis of the digits are three fleshy pads and an -intervening area of longitudinal ridges. - -The first question that arises in the attempt to analyse so complex a -grouping on a strange member like the foot of a _loris_ is this--what -is the primary function subserved by the ridges and their mode of -arrangement, and what may be their secondary uses? In the book -referred to I have maintained throughout, in opposition to Mrs. Wilder -Harris and others such as Dr. Hepburn, that the sense of touch is the -primary, and prevention of slipping the secondary adaptation secured -by the ridges. If this be true (and I know it is _sub judice_) there -is a very clear reason why the ridges should be longitudinal on the -tips of the digits on account of the better discrimination of small -objects secured by this arrangement, though it does not well assist -the _loris_ to avoid slipping. On D 1, as mentioned, the non-slipping -effect is secured by its ridges, and this digit is necessarily less -employed for discrimination than support. On the other hand the sloping -arrangement on the rest of the segments of D 3, 4, 5 is decidedly less -effective in preventing slipping than a transverse arrangement would -have been. I think I am justified in saying that too much has been made -of this secondary effect of the ridges in the prevention of slipping. -I know that the string wound round the handle of a cricket bat is very -effective for its purpose, but one can also understand that a casual -strand wound here and there on the handle as the ridges are on a -_hedgehog’s_ and _squirrel’s_ hand and foot would be of little use for -the purpose. - -On the other hand if the view may be entertained that on the palm and -sole of _hedgehog_, _squirrel_, _loris_ and man, we have written in -rows of papillary ridges and their modes of arrangement a register of -long-continued flexion of hand and foot in flexion and correlated -actions, we find the facts of these and numerous other Primates agree -in a remarkable manner with the hypothesis; whereas the exclusive -non-slipping rival has many awkward facts to explain, or disregard. - -Further as one has always to bear in mind the Mendelian analysis it -should be observed that the extreme variability, within certain limits, -of the arrangements of papillary ridges throughout the Primates renders -the hypothesis of unit-characters segregated, according to Mendelian -laws, wholly inapplicable to the _manner of their arrangement_ even -though perhaps not so to the _existence_ of papillary ridges. - -[Illustration: Fig. 62. Hedgehog--right foot.] - -[Illustration: Fig. 62A. Hedgehog--right hand.] - -[Illustration: Fig. 63. Common squirrel--left foot.] - -It may be bluntly asserted that the ridges are arranged as we find them -because, hands and feet being used as they are, the ridges “can do no -other,” and that there’s an end of it, and that we cannot derive any -help as to the origin of specific difference from such a trifle, the -next item on the agenda should be called for. As a piece of dialectics -that would be effective, but if taken literally it only goes to prove -my simple contention. - -It will be enough to mention the hand alone of the remaining series -with a note as to each animal. - -Fig. 64 gives the hand of a _chimpanzee_ with ridges on the pulps -resembling those of all the _apes_, _monkeys_ and _lemurs_, arched -groups on the digits and longitudinal ones on the centre of the palm, -both of these last two being exactly what would be found arising from -the actions of climbing branches and discriminating globular objects in -the palm. - -[Illustration: Fig. 64.--Chimpanzee--right hand.] - -[Illustration: Fig. 66.--Orang--right hand.] - -Fig. 65 is that of a _gorilla_ and its general features resemble -closely those of the _chimpanzee_ and of Fig. 66 which is that of an -_orang_. - -[Illustration: Fig. 65.--Gorilla--left hand.] - -[Illustration: Fig. 67.--Gibbon--left hand.] - -Fig. 67 of a _Hainan gibbon_ is very different on the palm from the -other three apes for its ridges are nearly all longitudinal or -slightly oblique, precisely as one would find this part if the _palm_ -were used very little for grasping boughs and much for discriminating -globular objects procured for its repasts. The wonderful long digits -of the gibbon form its main organ for supporting itself on branches -and swinging its body rapidly from branch to branch, and the arched or -nearly transverse ridges on the digits are placed just as the endless -use of them for this purpose would be likely to follow from it. This -example is a very clear one for showing, if it exist, the effect of use -and habit on the disposition of the ridges. - -Fig. 68 shows the arrangement of papillary ridges in a _lemur_ and 69 -that of a brown _sapajou_. - -Fig. 70 of the _Chacma baboon_, playfully called by the Boers Adonis, -is a very active and wary animal which lives on the rough rocky slopes -of the Cape. It is very much of a pedestrian and the response of its -mode of life and use of its forefoot is shown in five great pads of -muscle and efficient whorls of ridges for touch, those on the digits -being very nearly all transverse in accordance with simple flexion of -these joints. This again is what one would expect if my hypothesis be -sound. The purely non-slipping mechanism supposed by the rival view is -not here well supported by the facts. - -[Illustration: Fig. 68.--Left foot of ring-tailed lemur.] - -[Illustration: Fig. 69.--Brown sapajou, right hand.] - -Neither the arrangements of ridges (Fig. 61), in _loris_, nor the -_hedgehog_ (Fig. 62), nor the _squirrel_ (Fig. 63), need further -reference, but they are all, I think, very consistent with the -prolonged effects of use and habit. - - -Some Undesigned Experiments in Ridges. - -This section of the subject has afforded a good supply of indirect -evidence, but so far no direct proof that papillary ridges can be -created and disposed in their lines by pressure, friction and response. -The clearest case is one I brought forward at the Zoological Society -of London in 1905, and which was published in its proceedings of April -18th. It was an instance of the hand of a _chimpanzee_ with papillary -ridges produced in an aberrant or abnormal situation by walking, and -was given as follows:-- - - “In the course of an examination of the papillary ridges in some - specimens of anthropoid apes and monkeys certain groups of ridges - were found on the _extensor_ surface of the terminal phalanges of - the hand, apparently identical with those of the palmar and plantar - surfaces. Three specimens of chimpanzee living in the Society’s - menagerie were examined, of the ages: one year eight months, - two-and-a-half years and six years. In the oldest of these, called - “Mickie,” the ridges were definite and well-developed, on the second, - third and fourth digits on both hands; in the youngest specimen, - “Jack,” they were absent; and in “Jimmie,” two-and-a-half years old, - they were small and ill-defined, as if in process of development. - - Direction of Ridges. - - _Mickie._ Ridges longitudinal and reaching to the matrix of - the nail on the second, third and fourth digits. - - _Jimmie._ Showed ridges as follows:-- - - R. hand 1st D none. L. hand 1st D none. - 2nd " oblique. 2nd " oblique. - 3rd " transverse at base of D. 3rd " " - 4th " " " " 4th " " - 5th " nearly longitudinal. 5th " none. - - _In these three specimens ridges were absent from the corresponding - surfaces of the foot._ - - “The well-defined longitudinal direction of the ridges in “Mickie” - is worth notice. It must be remembered in this connection that a - chimpanzee walks with the extensor surfaces of the phalanges touching - the ground and the digits turned inwards, so that their long axis - are at right angles to the line of progression of the animal, and - accordingly the ridges of this part also occupy the same relative - position. There is no correlation in this instance between the act - of prehension and the direction of the ridges, though it agrees - closely with the general rule which obtains in so many regions, - that the ridges lie at right angles to the line of incidence of the - predominating pressure on the part.” - -In this example of ridges developed on an abnormal situation we see -what is, perhaps, an undesigned experiment as to the production of -ridges by a more frequent habit of walking in captivity than would -be found to occur in the wild state, for, as Lydekker says in the -_Royal Natural History_, Vol. I, p. 27, “When the chimpanzee goes -on all-fours, he generally supports himself on the backs of his -closed fingers rather than on the palm of the hand (see Fig. 6 of the -illustration on p. 15) and he goes _sometimes_ on the soles of his feet -and _sometimes_ on his closed toes.” - -[Illustration: Fig. 70.--Left hand of chacma baboon.] - -I have underlined purposely this word “sometimes,” for in the instance -I have described, not only the presence of the ridges and their -direction on the backs of the fingers but their absence on the backs of -the toes is significant, and I suggest that the _chimpanzees_ examined -have not sufficiently often exposed the backs of their toes to pressure -and friction for the production of ridges, whereas those on the backs -of the fingers have done so. Another point worth notice is that in the -oldest of the three _chimpanzees_, “Mickie,” æt six years, the greatest -number of ridges is present; in “Jimmie,” æt two-and-a-half years, they -were “small and ill-defined as if in process of development,” and in -“Jack,” æt twenty months they were absent. This would agree at any rate -with the hypothesis that the element of time and frequent repetition of -stimuli enter into the causation of aberrant ridges. - -A similar condition, with aberrant papillary ridges, has been found on -the digits of the hand of the _orang_. - -On the heel of adult man ridges are found surrounding it, of the -average depth of one inch from the plantar surface, and in one -particular case of a woman aged forty-nine, the depth of this area on -each foot measured was one and a half inches from the plantar surface. - -The extensor surface, or back, of the little toe shows ridges when it -is distorted by ill-fitting boots. - -In man ridges frequently appear on the radial side of the back or -extensor surface of the index finger to nearly the middle line of the -finger, and this is often more on the right than the left hand. - - - - -CHAPTER XIX. - -FLEXURES OF THE PALM AND SOLE. - - -Those flexures of the palmar and plantar skin which are called by -Galton chiromantic creases, and said by him to be no more significant -to others than palmists than the creases of old clothes, have received -a remarkable amount of pseudo-scientific attention since earliest -times in Chinese and Greek history. The former even added podoscopy to -their chiromancy. The line of life, the line of the head, the line of -the heart, the line of fortune and that of the liver, figure freely -in fortune-telling of modern drawing-rooms by women who ought to be -in Holloway gaol, but are not. The gipsies, their predecessors and -equally honest teachers, did not employ such high-sounding words, but I -believe that by observing closely the bearing, looks, dress and manner -of their dupes, while pretending to study their palms, both classes of -practitioners, like phrenologists, are able to tell a good deal of what -their customers _are_, and being shrewd persons they are able to guess -pretty well what they _will be and will do_. - -I agree with Galton that these creases of hand and foot are no more -significant than those of an old coat-sleeve, a pair of trousers, or -boots; but they are not less significant of certain muscular habits of -the wearers of those articles.[65] - - [65] Galton might have referred by way of illustration to an immortal - woman in _Martin Chuzzlewit_, who shall be nameless here. - -The flexures in question are in line with the subjects of the two -preceding chapters, and require little more description in detail than -is afforded by the accompanying illustration of mammalian hands and -feet. - - -Description of Flexures. - -There are two classes which may be conveniently called here Primary and -Secondary, the latter being too variable and accidental for further -notice. The former lie in three main directions and are longitudinal, -oblique or transverse. They represent in graphic characters the nature -and degree of the functions exercised by muscles moving the joints -which underlie them, and are often called “flexion-lines.” They are -“folds so disposed that the thick skin shall be capable of bending in -grasping while it at the same time requires to be tightly bound down -to the skeleton of the hands and feet, so as to prevent slipping of -the skin which would necessarily lead to insecurity of prehension, -just as the quilting and buttoning down of the covers of furniture -by upholsterers keeps them from slipping. For this purpose the skin -is tied by fibres of white fibrillar tissue to the deep layer of the -dermis along the lateral and lower edges of the palmar fascia and to -the sheaths of the flexor tendons. The folds, therefore, which are -disposed for the purpose of making the grasp secure, vary with the -relative lengths of the metacarpal bones, with the mutual relations -of the sheaths of the tendons and the edge of the palmar and plantar -fascia.... The sulci are emphasised because the subcutaneous fat, -which is copious in order to pad the skin for the purpose of holding, -being restricted to the interval between the lines along which the -skin is tied down, makes these intervals project, and these are the -monteculi.”[66] - - [66] A. Macalister, _Palmistry Encycl. Brit._, 11th Edition. - -This account of them from a leading anatomist shows that not for -nothing have these creases been evolved. They are inherited, have an -important function and are worthy of study in their humble way: they -may be even dignified with the name “character.” - -They are often double over the joints of the fingers and toes, but, -from the functional point of view and for simplicity, may be reckoned -as single. - - -Chief Types. - -[Illustration: Fig. 71.--Flexures on palm of right hand. Drawing made -from impression.] - -The most common types of them in the hand of man are shown in the -example given in Fig. 71. - - 1. A flexure over each phalangeal joint. - - 2. A flexure at the bases of the digits. - - 3. A flexure over the metacarpo-phalangeal joints of D 2, 3, 4 and 5 - with an oblique direction, called _linea mensalis_. - - 4. A flexure over these same joints and oblique in direction, but - nearer to the wrist--the _linea cephalica_. These flexures 3 and 4, - though arising from the flexion of one set of joints should be looked - at as separate folds because of their time-honoured popular names. - - 5. A curving flexure surrounding the thenar eminence, extending from - the centre of the wrist along the palm and terminating at the radial - border. - - 6. Variable longitudinal and oblique flexures not specified, which I - have called secondary. - -[Illustration: Fig. 72.--Foot of common squirrel.] - -[Illustration: Fig. 73.--Flexures on foot of vulpine phalanger.] - -[Illustration: Fig. 74.--Foot of loris.] - -[Illustration: Fig. 75.--Foot of ring-tailed lemur.] - - -Meaning. - -Whatever be the meaning and origin of these flexures they are not mere -folds such as one makes in a garment and leaves it so. Action, function -and fitting of the structures of the hand and foot are involved in -their history. They may loosely be termed “ergographs” without any -reference to the exact measurement of work done. No proper idea can -be formed of them if the original function and evolution of the -walking-pads of earlier mammals be omitted. If one goes back and back -until one reaches some lowly marsupial as a _vulpine phalanger_, or -insectivore such as a common _hedgehog_, one may even metaphorically -see these animals being fitted by a shoemaker with rude shoes or -walking-pads for the better locomotion on or under ground, or in the -branches of trees. These pads are projecting masses of hard fat with -fibrous tissue interspersed and they early become fitted or adapted -_to_ or _by_ the use to which they are put. It is impossible to suppose -that certain rudimentary pads are devised by selective processes prior -to the altered habits of walking of the animal that acquires them. From -the shoemaking point of view the fashion is rough and generalised, and -the changing habits of the animal adapt the shoe by degrees to the -function employed, much as many a private soldier knows to his cost -that he has had to adapt slowly and painfully his army boot to his -particular foot. This process in an early pedestrian mammal involves -the breaking up and limiting of the rudimentary pads by sulci in the -dense skin, and the process of struggle and adjustment between the -pads and their bordering furrows issues in the characteristic flexure -of each mammal. From experiences in the human body one knows how -easily fibrous adhesions between the skin and deeper parts, notably in -cases of Dupuytren’s contraction of the palmar fascia, are formed by -close apposition of the two layers. Such adhesion is precluded when -much movement of the part occurs, but _ex-hypothesi_ the rudimentary -flexures are distinguished by absence of movement, and the conditions -for fixing down the deeper layers of the skin to the bones beneath are -clearly present. That these are not indifferent structures is evident -from what Macalister says, and though they be small or even trivial may -be held to have acquired at some time or other selective value. Their -early stages would necessarily be too tentative, varied and slight to -acquire such value. - -[Illustration: Fig. 76.--Foot of squirrel-monkey.] - -[Illustration: Fig. 77.--Foot of macaque.] - -[Illustration: Fig. 78.--Foot of gibbon.] - -[Illustration: Fig. 79.--Hand of chimpanzee.] - -Fig. 72 is a sketch of the hand and foot of a squirrel (Sciurus) and -the numbers 1, 2, 3, 4, 5 and 6 are placed conspicuously on the walking -pads in accordance with the teaching of Dr. and Mrs. Wilder Harris as -to the six palmar and plantar walking-pads, of which the typical palm -and sole is constructed. The thick, black lines indicate the flexures -formed round the pads by the exercise of the functions of the hand and -foot. - -Fig. 73 represents the clumsy, thick walking-pads of a marsupial the -vulpine phalanger, _trichosurus vulpecula_. - -Fig. 74, the highly-developed prehensile foot of the loris. - -Fig. 75, the foot of a ring-tailed lemur. - -Fig. 76, the foot of a squirrel-monkey (Chrysothrix Sciurea). - -Fig. 77, the foot of a macacus (Macacus cynomologus). - -Fig. 78, the foot of a gibbon. - -Fig. 79, the hand of a chimpanzee and here the resemblance to the -_hand_ of man and _not to the foot of man_ is very striking. - -A description has already been given of man’s flexures of the palm. - -[Illustration: Fig. 80.--Drawing of flexures of sole of foot in young -adult.] - -Fig. 80 is a careful drawing of the sole of a young active woman -with a well-formed foot, and there is little typical in the mode of -arrangement of its creases except the slight tendency to transverse -lines of flexure. In all the feet I have examined I have found no -single flexure that is constant, and the longitudinal ones here shown -are often absent. - -Reviewing these examples one observes an evolutional decay of a minor -but necessary piece of mechanism of the Primate hand and foot. The -general similarity, _mutatis mutandis_, of the flexures of the palm -and sole in Primates is very noticeable, and is associated with the -strong prehensile power of the foot of all the forms below man. In -the cases of the two apes shown in this series, the resemblance is -still well marked, more so even in the chimpanzee than the gibbon, so -that the disappearance from the sole of man’s foot of any important -flexure is very significant of his loss of prehensile and gain of -locomotive perfection, and I find it impossible to conceive any process -of evolutionary change where a loss of the flexures of a prehensile -foot could come under the power of selection, on its own merits. On -the other hand this remarkable instance of disuse of a formerly useful -structure is adequately accounted for by the evolution of an organ -like the human foot which in course of long periods of time became an -organ of one function. Weismann might score a point over Spencer from -his laboured explanations of man’s dwindling little toe, but here, -I submit, he would have had to take refuge in silence, and pass to -characters of a higher and more debateable kind. - - - - -CHAPTER XX. - -THE EVOLUTION OF A BURSA. - - -A bursa exercises a function in the animal body which is the direct -opposite of that shown to belong to the flexures of the hand and foot. -Whereas the latter are adapted to the prevention of slipping in the -act of prehension, bursæ are delicate contrivances for producing the -maximum effect of sliding, within certain limits, between two opposed -surfaces, either between the skin and a hard surface beneath it, -between two muscles, or a tendon as it moves over a bone. As they are -very variable and most of them are inherited and congenital, while -some are produced only in the lifetime of the individual, they are -useful for consideration in regard to the questions of transmission of -modifications and of the origin of initial variations. Their degree -of utility ranges, for example, in man, from that of the prepatellar -bursa without which no useful movement of the knee-joint is imaginable, -to the insignificant bursa which may or may not be found on the -dorsal surface of a phalangeal joint of the foot. The principle laid -down by Lyell, to which allusion has been made elsewhere, that is, -of “explaining changes in the surface of the earth by reference to -causes now in action,” is applicable in this small department of the -evolution of a minor structure of the animal body. As man furnishes the -largest of all collections of these lubricating organs, his skeleton -and skeletal muscles will form the main subject of this chapter, and I -venture, if one may say so, to “Lyell” them. None of the sections of -this book except that on the mammalian hair affords so simple and easy -a field for watching in operation certain mechanical forces. We may -here go down to the potter’s house and watch him moulding his clay, or -the cobbler his leather. So much are bursæ in the human body under the -power of extraneous forces that I venture to say that if some young -surgeon of an inquiring mind were to choose a place and time when the -Honourable and Vigilant Stephen Coleridge was out of the way, and were -to produce in a young _chimpanzee_ under an anæsthetic a “greenstick -fracture” of his radius and ulna, immobilising it at a right angle -for a month, the animal would exhibit at his death some years later a -highly developed bursa over the bony protuberance nearly as good as -the olecranon bursa on the uninjured side, and better than that of the -injured limb. As I have reason to know the meticulous vigilance of this -professional and expert humanitarian I hasten here to say in advance -that I do not recommend this experiment, not because it would not be -entirely justifiable, but because nature herself in the highest Primate -has produced many undesigned experiments of nearly equal value, as I -hope to show. - - -Bursæ Described. - -Broadly considered a bursa is a sac lined by synovial membrane, and an -extreme example of the simplest form in which it is found may be said -to be that of the condition found in a domestic dog. Under its skin, -except on such regions as the snout, the tail and the feet, there is -hardly a place where a bursal surface does not exist. Here and there -trabeculæ may divide the great sac imperfectly, but from the protective -and selective point of view this mechanism under a dog’s skin may be -compared to the oil with which an Indian criminal lubricates his naked -body so as to elude capture. To us who are too familiar with dog-fights -(to which the Hon. Bertrand Russell likened the recent Great War, as we -all remember) and who know how much noise and ferocious attempts are -made by the warriors to bite one another, and how little success they -achieve, the beautiful adaptation of nature in the dog far surpasses -that of the Indian criminal. Indeed the latter may well have been -suggested by the former. - -Between such a simple and undifferentiated bursal surface as this and -another such as the small but essential bursa under the tendo achillis -there are endless variations adapted to particular uses and regions. - -The description of bursæ given by Macalister is too clear and good not -to be given in his own words.[67] - - “Synovial membranes are found either as the lining of joints, or as - _Bursæ_, which are closed sacs (_a_) between contiguous soft parts, - or (_b_) beneath soft parts which glide tensely over a bone. Bursæ - are formed around and beneath tendons in the neighbourhood of joints; - and the hard part on which the tendon plays is often invested with a - layer of cartilage over which the synovial membrane does not extend. - When they completely surround tendons, as in the finger and toes they - are called _thecæ_ or sheaths, and the tendons are connected to the - sheaths by synovial reflections. Sometimes bursæ lie between exposed - areas of skin and projecting bony points, such as the patella, - olecranon, ankles, etc. - - “Their (synovial) membrane differs from the synovial membrane of - joints in not having so continuous or definite an endothelial lining; - indeed, while some bursæ, such as that beneath the ligamentum - patellæ, have a more or less regular lining of regular endothelium, - others have only elongated connective cells forming an imperfect - lamella, and there are all possible gradations met with between - the regular saccular bursa, and a loose meshwork of areolar tissue - of which the bursa is only a specialisation. Bursæ may be (1) - subcutaneous, (2) subfascial, (3) between two tendons, or (4) - between tendons and subjacent ligaments or bone. Of these, some - communicate with the neighbouring joints always, some occasionally, - and some never. Bursæ underlying parts which have an extensive range - of motion are _unilocular_, with a single cavity. Bursæ spread - over an extensive surface, and whose walls move but little on each - other, are often divided by imperfect fibrous septa, and are called - _multilocular_. Almost all the lesser bursæ are unilocular, most of - the subcutaneous bursæ are multilocular.” - - [67] _Text Book of Human Anatomy._ A. Macalister, 1889, p. 48. - -Now if one were not engaged upon such a problem as that of initiative -in evolution and in trying to give examples of it there would be no -Gordian knot to cut, and the condensed statement of Macalister might -be simply taken as an accepted account of the manner in which reading -between the lines a bursa is formed in the animal body. But, when an -hypothesis such as the present is in question, one may not cut the -Gordian knot in this way, and must produce briefly certain observations -of the process, not only those known in man by anatomists and surgeons -but also some found in lower Primates. - - -Human Bursæ Enumerated. - -The following is a list of bursæ in man of which some are normal -or always present, and others which are both occasional in their -appearance and often imperfectly developed. - -_Front of Neck._ - - (A) One in front of the pomum adami. - - (B) One in the thyro-hyoid space extending to the under surface of - the hyoid bone. - - (C) One beneath the stemo-hyoid muscle. - - (D) One above the hyoid bone. - -_Pharynx._ A small central pit constituting a single bursa the _bursa - pharyngea_. - -_Behind the angle of the lower jaw._ One. - -_On the symphysis of the chin._ One. - -_On the Acromion process._ One. - -_Beneath the deltoid_ and the acromion process, one large bursa often - opening into the shoulder-joint. - -_Elbow._ - - (A) One over the olecranon. - - (B) One occasionally over the inner epicondyle. - - (C) One over the internal condyle of the humerus. - - (D) One over the external condyle of the humerus. - - (E) Small one between the biceps tendon and the head of the radius. - - (F) Often a second bursa which separates the tendon from the oblique - ligament crossing it. - -_Wrist._ - - (A) One over the styloid process of the radius. - - (B) One over the styloid process of the ulna. - -_Hand._ - - (A) One over each of the metacarpo-phalangeal joints. - - (B) One over each of the phalangeal joints. - -_Region of hip._ - - (A) One over the anterior superior spine of the ilium. - - (B) Large one between the great trochanter and the gluteus maximus - muscle. - - (C) One between the gluteus medius and the bone. - - (D) One between the gluteus minimus and the bone. - - (E) One between the psoas and iliacus muscles often opening into the - hip-joint. - -_Thigh._ - - (A) One over external condyle of the femur. - - (B) One over internal condyle of the femur. - -_Knee-joint._ The prepatellar bursæ. - - (A) Between the skin and superficial fascia at the lower edge of the - patella there is often a small subcutaneous bursa. - - (B) Beneath the superficial fascia over the fascia lata there is - always a large interfascial bursa, intersected by smooth fibrous - bands extending downwards over the upper part of the patellar - ligament. - - (C) One still deeper between the deep fascia and front of the bone - there is a layer of lax connective tissue. - - (D) Sometimes a third or deep subfascial bursa. - - “These bursæ over the knee-joint appear in fœtal life and vary in - size in persons of different occupations, being often large in - housemaids and carpet-nailers, and often communicating with each - other.”[68] - - [68] Macalister, p. 488. - - (E) Occasionally the upper part of the synovial pouch of the - knee-joint is shut off from the general cavity and forms a separate - bursa beneath the extensor muscles. It always communicates with the - knee-joint though originating independently. - -_In the Ham._ - - (A) Large bursa between the inner condyle of the femur and the - gastrocnemius muscle, often opening into the joint. - - (B) A smaller one on the outer side. - - (C) One between the biceps tendon and the external lateral ligament. - - (D) One between the semimembranosus } - - (E) One between the popliteus } - - (F) One between the sartorius } and the bone. - - (G) One between the gracilis } - - (H) One between the semitendinosus } - -_Tibia._ - - (A) One over the tuberosity. - -_Ankle._ - - (A) Over both malleoli. - - (B) Between the tendo achillis and the os calcis. - -_Foot._ - - (A) Over plantar surface of the great toe. - - (B) Over plantar surface of the little toe. - - (C) Over the dorsal surfaces of all the phalangeal joints of the toes. - - (D) Over the dorsal surface of metatarso-phalangeal joint of the great - toe. - - (E) Over the plantar surfaces of the metatarso-phalangeal joints of - all the toes. - -I calculate that there are at least fifty-two separate bursæ (about one -hundred on the two sides of the body) in the normal or fully developed -state, though of these many will be found either absent or with very -little of the full structure of a bursa. One small but significant -point may be referred to here. We are all familiar with the prominence -of the knuckles of the hand and the very efficient bursæ which cover -them, but most persons do not recognise that the foot has no such -knuckles (or prominent metatarso-phalangeal joints) and no bursæ over -these joints, except that of the great toe which happens to be very -much more exposed to friction and has a much greater range of action -than the other four metatarso-phalangeal joints. This might be called -by some persons a beautiful bit of adaptation _for_ locomotion and by -others an equally admirable bit of adaptation produced _by_ locomotion. - - -Examination of Two Still-born Children. - -Some further light may be thrown upon the human bursæ by an examination -of two still-born children I dissected in 1908 in Lewisham infirmary, -and give here the results as to the more important subcutaneous bursæ. - -_Male Child_: full term. - - _Shoulder_: bursæ under acromion processes absent. - - _Elbow_: bursæ over outer condyle of humerus present. - - " " inner " " absent. - - " " olecranon both present. - - _Wrist_: bursæ over styloid process of ulna present. - - " " " " of radius present. - - _Hand_: bursæ over metacarpo-phalangeal joints D 1 absent, D 2, 3, - 4, 5 present. - - bursæ over phalangeal joints, first set present, second set - absent. - - _Hip_: bursæ over anterior superior spine of the ilium both absent. - - _Knee_: prepatellar bursæ well-developed. - - _Ankle_: bursæ over both malleoli present: - - bursæ beneath tendo achillis well-developed. - - _Great toe_: plantar bursa present. - - _Little toe_: plantar bursa absent. - - _Toes_: D 1 (great toe) bursa over metatarso-phalangeal joint - present. - - D 2, 3, 4, 5 bursæ over metatarso-phalangeal joints absent. - - Bursæ over _Phalangeal joints_. - - D 1 present. - - D 2, 3, 4, none over either of the phalangeal joints. - - D 5 bursa present over the first and absent over the second - phalangeal joint. - -This example of a still-born, but otherwise normal infant illustrates -well the previous statement that certain bursæ are congenital and -others of less functional importance are formed after birth. Whereas -the olecranon, wrist, patellar, ankle and tendo achillis bursæ are -fully formed, those under the acromion processes, one of those of the -condyles of the femur, and the digits of the hand, those over the -superior anterior spines of the ilium and those of the foot are little -if at all developed in this case. - -Another still-born child at seven months was also dissected and this -had well-formed prepatellar bursæ, scanty ones over the olecranon -processes, also over the small joints of the hand and foot where they -were difficult to isolate and over the malleoli they were only slightly -developed. - -A fœtus in spirit I examined and found no commencement of a prepatellar -bursa. - - -Examination of Living Primates. - - -_Anthropoid Apes._ - -Eight of these I examined during life at the London Zoological -Society’s gardens in 1908, four _chimpanzees_, two _orangs_ and two -_gibbons_. These afforded the opportunity of ascertaining by means -of touch the presence, and in a minor degree the size and efficiency -of the main subcutaneous bursa, just as one can do this in a human -subject. The _chimpanzees_ were A, aged thirteen; B, aged seven; C, -aged three; and D, aged two-and-a-half years; the orangs E, aged -thirteen; F, aged three years; the gibbons G and H both two to three -years. - -These eight specimens possessed good examples of the leading -subcutaneous bursæ over the olecranon process, the styloid process of -the ulna, the patella and both malleoli. - -The smaller and less definite bursæ gave the following results. - - -_Chimpanzees._ - - A. _Hand._ Bursæ on all the metacarpal and first phalangeal - joints; none on the second phalangeal joints of D 2, 3, - 4, 5. - - _Foot._ Bursæ well marked on the five metatarsal first phalangeal - joints; none on D 2, 3, 4, 5 joints, but one on that of D - 1. None found on second row of phalangeal joints. - - B. Moderate development of bursæ on metacarpo- and - metatarso-phalangeal joints of D 1; doubtful on those of D 2, 3, - 4, 5. - - On hand and foot first phalangeal joints, bursæ present, on second - row absent. - - C and D were similar. Metacarpo- and metatarso-phalangeal joints, - none in C and scanty in D. - - No bursæ on any phalangeal joints of hand or foot. - -_Orangs._ - - E. Metacarpo- and metatarso-phalangeal joints, bursæ ill-developed, - first row of phalangeal joints of hand and foot moderate, second - row none. - - F. Metacarpo- and metatarso-phalangeal joints more marked than in E., - and well developed on all phalangeal joints. - -_Gibbons._ - - G. Metacarpo- phalangeal and metatarso-phalangeal joints poorly - developed on D 2, 3, 4, 5, and none on those of D 1. Absent on all - phalangeal joints. - - The digits of the gibbons were very long and evidently efficient - in action, but were never flexed to any great degree. - - -Dead Specimens. - -I also examined the hands and feet after death of certain lower -Primates in 1909:-- - - H. Hapalemur Griseus. - I. Hapale Jacchus. - J. Cercopithecus Callitrichus. - K. Cercopithecus Mona. - L. Macacus Rhoesus. - -_Hapalemur Griseus_ H. _Hands._ No bursæ on styloid processes of radius - and ulna, and no localised bursæ on any metacarpo-phalangeal or - phalangeal joints. - - _Feet._ Bursæ under tendo achillis small but distinct. Present over - both malleoli. - - Metatarso-phalangeal joints D 1, 2, 3, rudimentary D 4 and 5 - absent. - - First phalangeal joints of D 1, 2, 3, 4, rudimentary absent - over D 5. - - Second phalangeal joints absent on all digits. - -_Hapale Jacchus_ I. - - _Hand._ Lower end of ulna, which is very prominent, a bursa present, - over end of radius, _which is much less prominent_, absent. - - Metacarpo-phalangeal joints, present in all. - - First phalangeal joints, which are prominent, present in all - digits. - - Second phalangeal joints absent in all. - - _Foot._ Bursa under tendo achillis and over both malleoli. - - Metatarso-phalangeal joints absent on D 1; present on D 2, - 3, 4, 5. - - First phalangeal joints, present in all. - - Second phalangeal joints, absent in all. - -_Cercopithecus Callitrichus_ J. - - _Hand._ Dorsal surface of the whole hand shows no localised bursæ, - only a loose areolar tissue under the skin. Styloid - processes of radius and ulna no bursæ. - - _Foot._ Dorsal surfaces over the whole foot similar to that of the - hand. - - Bursæ present over both malleoli. - - Well-formed small bursæ under tendo achillis. - -_Cercopithecus Mona_ K. - - _Hand and Foot._ Dorsal surfaces similar to those of J and similar - loose areolar tissue over styloid processes of ulna and - radius. - - Bursæ over both malleoli. - - Well-formed bursa under tendo achillis. - -_Macacus Rhoesus_ L. - - This specimen showed more examples of bursæ than the two - of Cercopithecus. - - Bursæ present over styloid processes of ulna and radius, - also over metacarpo-phalangeal joints. - - Bursa well-marked over malleoli and under tendo achillis. - - Bursæ present over metacarpo-phalangeal and - metatarso-phalangeal joints. - - No bursæ over phalangeal joints. - - -Further Undesigned Experiments. - -The preceding facts as to the natural history of bursæ in man and -some lower Primates, even if they stood alone, are enough to produce -conviction as to the manner in which bursæ of all degrees of perfection -are formed by function, and point to the origin of the initial stages -of these structures. But they do not stand alone, for in man there -have been carried out certain undesigned experiments in a similar -direction, comparable to those described in the sections on direction -of hair and arrangement of papillary ridges. These demonstrate the -fact that frequent friction of skin over a hard surface has the power -of producing adventitious bursæ in regions where they are not found in -the normal state. - -These adventitious bursæ are the following:-- - -In the first place certain normal bursæ in important situations are -frequently so much enlarged by the constant irritation of pressure and -friction that they become considerably enlarged. This enlargement may -go on to definite pathological changes and thus come under the care of -surgeons. - - They are Prepatellar bursæ--“housemaid’s knee.” - Olecranon bursæ--“student’s elbow” and “miner’s elbow.” - Tuber ischii bursæ--“weaver’s bottom.” - -These may be called “occupation-bursæ” and may be classed with three -other well-known adventitious bursæ which are formed on the shoulder -in “deal runners,” on the scalp in “fish porters” and in the back of -the neck in Covent Garden porters, known as a “hummy.” Entirely new -bursæ are formed also over the cuboid bone in talipes equino-varus, -over the internal condyles of the femur in bad cases of knock-knee from -friction of one joint against the other, over the prominent vertebrae -in a humpback. A structure closely resembling a bursa and arising -from similar causes to those producing adventitious bursæ is found in -unreduced dislocations or ununited fractures. - -A small example of an adventitious bursa came under my notice. A woman, -E. L., aged 49, had remarkable enlargement of the metatarso-phalangeal -joint of her great toe of the left foot, and over this joint was formed -a well-marked bursa on the dorsal surface. The right foot showed a -much less prominent joint and only a very slight development of the -corresponding bursa. - -This instance of a bursa-like structure being produced in unreduced -dislocations and ununited fractures suggests the conception which I -here propose, but do not attempt to verify that _all joints in all -animal forms from the lowest up to man have been evolved in a manner to -which this pathological experiment may give a clue_. - -A remarkable case reported by Sir William MacEwen in the Royal -Society’s _Phil. Transactions_, Series B, Vol. 199, pp. 253, 279, is -worth referring to in this connection. It was a case of a growth of -bone in muscle connected with an old injury to the thigh of a man 38 -years old, and healthy. At the operation performed by the author of -the paper the tumour was found to be movable, partly attached to the -fascia lata of the thigh, and the upper part of the tumour moved on -the lower. It was found that the tumour consisted of two parts, the -upper three-and-a-half and the lower seven inches long, altogether -a mass about ten inches in length. Muscular bundles of the vastus -externus were included in this ossific formation, one passed through a -tunnel in the bone through which it worked, and the sides of it were -polished. _At the point where the newly formed bone came in contact the -surfaces fitted each other and were polished as if they were covered -with cartilage, and were here surrounded by a capsule._ (Italics not in -original.) This fibrous covering when opened was seen to contain a thin -serum, which, though not of the consistence of synovial fluid, still -aided in lubricating the polished surfaces as they played over one -another. - -A similar case was reported also by Dr. C. Paterson, surgeon to the -Glasgow Royal Infirmary. - -A very interesting address by the Hunterian Professor, Mr. Jonathan -Hutchinson, was given in February, 1917, on Dupuytren’s work, -especially in the discovery of the cause and treatment of the -contraction of palmar fascia known by his name. Professor Hutchinson -described his method of curing this by the removal of the head of -the first phalanx, and showed excellent results and evidence of the -formation of a perfect new joint to take the place of the old distorted -one, and the fingers were as efficient as in the normal state in the -exercise of flexion. He gives photographs of the hand some months after -the operation showing it to be capable of easy and full extension as -well as of flexion. This again agrees well with the cases of Sir W. -MacEwen and Dr. Paterson of the formation of a functional joint _by_ -use and habit. - -Another distinguished Hunterian Professor A. Keith, also gave two -lectures in January, 1918, on the “Introduction of the Modern Practice -of Bone-grafting,” which, in its modern form, he assigns to the credit -of Sir William MacEwen. He lays great stress on the important work -performed in such cases by the osteoblasts without whose living and -formative action these results could not be obtained. He explains how -necessary it is that these living elements should be stimulated into -action by _work_. They thrive only so long as they have work to do. -Another surgeon, Ollier, “wondered why the fragments of bone which he -had succeeded in raising from slips of periosteum planted beneath the -scalp or amongst muscles ceased to grow and tended to disappear. These -bony grafts withered because they were not subjected to the strains -and stresses which rouse the activity of osteoblasts.” MacEwen, “by a -fortunate chance, planted his tibial grafts in a situation where they -soon became subjected to muscular strains and stresses. In a short -time bony fragments gathered from the legs of six boys became intrinsic -parts of the humerus of a seventh; from the moment of primary union the -bone cells of the graft were brought under the stimulating impulses of -the biceps and triceps. Osteoblasts are the obedient slaves of muscles; -_muscular dominance is their breath of life_.” (Italics not in the -original.) - -“Wolff was the first to devote thirty years of constant work and -observation to prove that the shape and structure of growing bones -and adult bones depend on the stresses and strains to which they are -subjected. By altering the lines of stress the shape of a bone can be -changed.” - -Wolff’s law is simply this: “Osteoblasts at all times build and -unbuild, according to the stresses to which they are subjected.” - -Professor Keith says further: “We are driven, as I have pointed out in -a previous lecture, to look for the primary cause, not in the bones, -but in the muscles, particularly in those which are tonically and -constantly in action so long as we are standing.” - -A terse expression of Wolff’s law is quoted from Dr. John B. Murphy, of -Chicago: “The amount of growth in a bone depends upon the need for it.” - -A remarkable illustration of a similar process is given in the -construction of sponges by the scleroblasts and it is stated: “The -soft walls of this sponge are constantly exposed to the force of -moving waters, and we shall see that the spicule-builders--the -scleroblasts--are endowed with the same properties as osteoblasts--the -powers of fashioning and depositing the elements of the skeleton so -that the sponge can best resist the forces to which it is habitually -exposed.” - -One more important quotation from this lecture will suffice. “No -one who has watched the behaviour of scleroblasts and marked the -design in their workmanship can doubt that they have acquired certain -characteristic qualities, chief of which is a sensitiveness to -vibrations--to stresses. We see them build the same form of spicules as -their ancestors, and therefore must suppose that their building quality -is a gift of inheritance. We see them alter their mode of building as -stresses change; we must therefore suppose that their inherited powers -can be changed by the circumstances under which they work.”[69] - - [69] Hunterian Lecture on “The Introduction of the Modem Practice of - Bone-grafting.” Royal College of Surgeons of England, January, 1918. - Reported in the _Lancet_, February 9th and 16th, 1918. - -In regard to the action of the scleroblasts of sponges I have only -to point out that the cautious words of Professor Keith on the -treacherous ground of inheritance amount to the very same conception -of personal selection and inheritance as are involved in the term -“educability” of Sir E. Ray Lankester. Whether or not in the case of -sponges this be a complete account of the matter it at any rate is a -very important piece of evidence, if valid, for selection. Whether or -not further it is a piece of evidence for a Mendelian factor implicit -in the primordial sponges and released by some loss of inhibiting -factors, as Professor Bateson would probably claim, is another and -far more imaginative conception. The mere neo-Lamarckian with the aid -of personal selection fails to see any difficulty in realising the -wonderful process described by Professor Keith. - -An apology must be offered here to the patient reader for the -introduction under the heading of the “Evolution of a Bursa” of the -apparently alien subjects of bone-grafts, artificial new joints and -sponge-spicules, but I have hazarded the guess that all joints in all -animals have been fashioned--“forged by the incident of use,” to employ -a fine phrase of Professor Macdonald’s in another connection--in slow -but intelligible ways by use, and that in them, as elsewhere, function -has preceded structure. This arose so simply out of the story of the -bursæ that I ventured to digress as aforesaid rather than make it the -subject of a separate section. - - -The Significance of the Proceeding. - -The foregoing slender contribution to the comparative anatomy and -physiology of bursæ is sufficient to show that at certain important -and “critical” points in the mammalian anatomy, efficient bursæ are -always present. One cannot indeed conceive the function of the parts -involved being carried on at all without these ingenious contrivances, -and no doubt can exist that in certain of the leading bursæ selection -guides and guards, while use and habit maintain them. Over such as -these “dominance” or the appearance of mutations might perhaps be -supposed to preside, and possibly some useful statistical results might -arise from their study from these points of view. But, between these -major bursæ in man and lower Primates and the undifferentiated sacs -which hardly deserve the name of bursæ, there is a perfect little host -of insignificant structures, which at the first attempt at dominion -over them on the part of Mendel or de Vries would hoist the standard -of revolt. These would even refuse allegiance to Personal Selection -under the persuasive banner, “Educability,” which however valuable -elsewhere, must stand aside in this little province of Nature. I have -thus attempted to “Lyell” this body of facts. Basing the statement on -an analysis of a considerable mass of small facts which no one disputes -I claim that the modifications drawn from normal anatomy on the one -hand and on the other adventitious structures, produced by acknowledged -mechanical forces, are examples of the transmission of modifications, -and illustrate the mode of formation of certain initial variations. In -other regions where Plasto-diēthēsis, as I conceive it, is at work in -producing adapted organisms, there may be included in the hyphenated -area certain factors of heredity, Mendelian, mutational and others, but -not in this group. This is merely an assertion of an opinion though I -submit that there is good evidence for it. Not even the hardest hearted -Weismannian, Mendelian or mutationist, and not even the biometrician -can refuse to this poor little province the required time and -mechanical forces, and, unless an opponent can offer some explanation -more consistent with the facts than that here offered, the proof of -causation is as sound as that shown in the larger one of the direction -of hair. - - - - -CHAPTER XXI. - -THE PLANTAR ARCH. - - -The principle of Lyell cannot be applied to this section of my -subject for it is unique in the animal world. There is here a simple -compilation of facts such as the medical schoolboy is supposed to know, -and only requires for its setting forth the valuable expert knowledge -of our predecessors in anatomy. It is indeed a pedestrian chapter. - -Man alone possesses this mark of a high lineage, and it adds point to -Shakespeare’s description of man as “paragon of animals,” and Huxley’s -“a superb animal, head of the sentient world.” For winning this -integral part of a perfect walking-foot man must stoop to conquer; he -must descend from the trees in order that he may have life and liberty; -whether he bears the ancient surname of Tarsius or the more honoured -one of Pithecus matters not. Names had not in those early times usurped -that tyranny over man’s mind which they have done among his modern -descendants. He came into that terrestrial kingdom which was to be -his own with many a limitation, but with the promise and potency of -an unexampled evolution, when he assumed more fully the erect posture -and saw that his inheritance was very good. Neither then nor since has -he ever reached the fleetness of foot of the Thibetan wild ass, the -astonishing sense of smell of the dog or horse, the keen sight of the -hawk, or the climbing power of that simian family upon whom he turned -his back as on a poor relation. He became _par excellence_ the walking -biped of earth, as, even with greater value to his mastery of the -world he learned to talk in articulate language. A walking animal and -a talking animal, with vast stretches of time for training these new -powers of his, he became modified into the variegated human stocks, -black, yellow and white, that now inhabit the earth. - - -A Crumbling Arch. - -A digression, I hope, will be pardoned here before the value and beauty -of the plantar arch and its mode of forging are described, and it is -possible the latter may add some force to the former. Scientific (or, -must I say?) semi-scientific writings are not concerned with the -snobbishness of much of the pride of birth which still survives among -us. But I would indeed think myself to be doing “my bit” if I could -induce the present generation of young women and men to think highly -of their plantar arches, nobler evidence of a “good” family than soft -fair skin, taper fingers, Grecian nose, slender waist or that hair of -which the decaying line of the long-haired kings of old France were -too proud. For one reason or another, probably analogous to those for -which he has lost so much the vigour of his hair of the scalp, or his -dwindling wisdom-teeth and shrinking little toes, in other words, -racial degeneration, modern man seems to be losing his plantar arch. -For about three years I have made careful but saddening study of the -ankles and feet of young women, and have embodied it in a variety -of journals. This study has included about two thousand examples in -young women of incipient or advanced flat-footedness as revealed, -nay, flaunted before us in our towns and villages. This revelation -has been offered by women’s shortened skirt, so that one can now note -for oneself the ugly and disabling ankles and feet in the streets of -any town, without the complicated business of a surgical examination. -Such an examination, as it happens, and as it is usually undertaken, -serves only to show a moderately advanced degree of this deformity, -indeed, just so much as induces a patient to go to a doctor for relief -of pain or obvious deformity. This is wholly insufficient for the study -of a defect which in the various degrees of its development affects -nearly 90 per cent. of all youngish women so far observed and noted. -The doctors may--or may not--cure this evil, but they are not likely -to find time even to discover during their strenuous lives, the great -spread of this physical defect. But the merciful ukases of fashion, -from Paris or elsewhere, and the obvious benefits, for once, of a -fashion, are so powerful that the short skirt has remained with us for -several years past and does not seem likely to go. I can only hope it -will last until women who lead their sex in these days become ashamed -of the feet of their sisters and their own, and make a forcible attack -upon the Health Minister or Minister of Education, or both, so that -systematic foot-drill in all elementary schools may be established. -No other means than this, added to improved general health, can be -conceived as able to correct so widely spread a deformity. I do not -desire to be considered as making an attack on the bodily charms of -women, for whose multifarious attractions I yield to none in sincere -regard. But here is the revelation, here are the cases walking -unashamed before us, and if the skirts _should_ lengthen again and -cruelly hide up the evil, no one will be induced again to take up the -unpopular attitude of saying that nearly all young women have feet that -are deformed and ugly and, therefore, more or less inefficient. There -is, alas! only too much reason to know that the evil is great among the -better class, even of boys, for in 1919 Captain Coote said publicly at -a Schoolmasters’ Conference that fully 30 per cent. of the new boys -entering leading public schools had flat-foot, and Captain Coote, the -highest exponent of physical training in the Navy, knows a flat-foot -when he sees it. The measures here suggested in connection with the -feet of women have the great merit that from them boys and girls will -alike benefit. - - -Non-Arboreal Man. - -Many problems faced non-arboreal man as he descended from the trees -to claim his suzerainty and place of toil. Not least among them was -the question of methods of protection against the terrible creatures -among which he was to live. Their production must needs be slow, and -for him to meet by “direct action” with weapons invented _ad hoc_ -the fierce large carnivora and clumsy but dangerous dinosaurs would -have proved highly dangerous. Too long had they been in possession -of his Canaan, and he could not cross his Jordan, walk seven times -round their Jericho, blowing with trumpets of rams’ horns, and on the -seventh day march in and “consolidate his position.” He had first to -do what his descendants have always been bound to do; he had to learn -to walk terrestrially long before he could think and live imperially. -Sufficient for him was the evil of his day, and, as an old arboreal -denizen he had much to learn and not a little to unlearn; and we know -from the prehistoric pictures of his own doings and trophies, that he -did in course of ages learn to walk, run and jump with variety of step -and efficiency unknown in any other Primate group. We can ask, and we -can but supply speculative answers as to the details of _how_ he did -it, but somewhere and at some time he learned first to become as good a -walking animal as later he became a talking one, and some at any rate -of the steps of the process are plain for all to read to-day. - - -How the Arch was Built. - -Did I not know something of the severity of the judges in such a -Court of Appeal as we are facing in this case and of the opposing -counsel--of the jury I have less fear--I should be disposed to settle -on a half-sheet of note-paper the problem that non-arboreal man settled -ages ago for himself on the ground, by a familiar saying. It really -meets the non-scientific mind which is not weighed down by what Captain -Marryat used to call “top-hamper,” to answer _Solvitur Ambulando_. But -I hear judges and counsel both saying “This will never do,” and must -address myself to opening up the case. - -If an adventurous gorilla and his mate, whom we may call gorilla -Columbi, had long ago made a bid for a life completely terrestrial -rather than partly arboreal, it is difficult to imagine how the feet -of this pair could have failed to adjust themselves and their separate -tarsal elements to a better if rudimentary form like that of man, and -that their progeny would not have followed or improved upon this. -Professor Keith,[70] in his work referred to, and Professor Wood Jones -in _Arboreal Man_, have much to say on the evolution of man’s foot -and arch, and I mention this _ab initio_ so as to be free from any -supposed claim to originality which is apt in the present extended -range of scientific progress to be as damaging to a man as for him -to proclaim his honesty or a woman her virtue. And I also formally -grant to the Mendelians and Mutationists, without offence and with -some possible relief to their minds, a period of leave from this poor -trench-warfare--_Plasto-ditēthēsis_ will not be obliged to call in at -the place of its hyphen any reinforcements from these of the higher -command. - - [70] _Human Embryology and Morphology._ - -The assumed precursor of our human walker was probably more highly -evolved in his own special line than the real ancestor, but we have so -little yet of discoveries of whole skeletons of earliest man that the -bodily structure of gorilla C. may fairly be taken as a starting point, -indeed he is for this purpose a valuable lay-figure, almost artistic -for once, on which may be draped the following story of the making of -an arch. The ultimate verdict, which word I use in the old English -sense of a “true saying” rather than the most recent declaration of -those who “ride on white asses and sit in judgment,” does not therefore -invalidate the verisimilitude of this picture. One may go farther and -affirm that, given certain anatomical and physiological facts in an -earlier Primate stock, which marvellously resemble those of modern -man, and it must follow as the night the day that his more primitive -physical basis employed in a new mode of progression, that is of -terrestrial walking on two feet, will be converted by use and habit -into the construction of such new formations as will best agree with -the new style--in other words, in this instance, a plantar arch. - - -An Unique Phenomenon. - -That a plantar arch is peculiar to man is a matter of fact, and -Lydekker in the _Royal Natural History_, Vol. I., p. 41, says of -the gorilla’s foot incidentally “there is no sort of resemblance -to the human instep in the whole foot,” and Professor Keith in the -work referred to “the arch is a human character.” One may see this -for oneself in living apes and monkeys and in the wonderful series -of drawings of apes in all kinds of postures in the _Royal Natural -History_, and indeed in the feet of dead apes and monkeys. All Primates -other than man walk on a flat sole. - - -Equipment. - -Our adventurer starts with the following equipment of tools for making -his arch as he learns to walk entirely on the ground which it must -be remembered he can only do by unlearning _pari passu_ his highly -cultivated power of grasping with his foot. The old and the new cannot -flourish together. The evolving foot of man is an example of a slow -change in the function of an organ and consequent modification of -certain structures in it. He walks with his feet turning in, or in the -axis of the leg; his great toe is not in this axis but may even lie at -a right angle to the foot; he rests weight on his heel and even more on -the outer border of his sole, and thus the sole of one foot turns more -or less towards the other; and he puts a good deal of weight on his -toes which are frequently doubled over; and his gait, though erect, is -never completely so, and is clumsy in appearance. - -_Bones_: his heel-bone is relatively long and pointed and slightly -arched below; the bones of his great toe are short and thick, and the -other four toes relatively long and slender. You can see at once it -is not primarily a walking foot. Any active boy of twelve could give -him points and a beating in a race for life in the open. Further, his -foot shows a much larger proportion of the whole foot in front of the -end of the great toe than is ever seen in man. The _ligaments_ which -bind the joints of his foot together, while the muscles play upon them, -are little different from those he will require for the girders of his -arch, except for such a throwing out of slips, and shifting under the -stresses and strains of such walking as his new gait involves. - -The _muscles_ of his leg and foot are the most important by far of his -original equipment with which to set about making his arch: he could no -more do this out of his present muscles than a Hebrew could make bricks -without clay. It is these variable and plastic structures which are -most readily adapted by use in a fresh direction or increased degree. -He has the great flexors of the ankle and foot in his poorly-shaped -calf (this feature might be adduced as a human character and studied -in this manner if it were not of so elusive a nature) and the long -flexors of his four outer toes, the special long flexor of the great -toe, which in his case does not of course act in the axis of the other -metatarsal bones. He is lacking here in the special detached portion -of the _flexor accessorius_, which eventually becomes of use in -maintaining the arch, between the heel-bone and the tendons of certain -digits. He has, in a measure, the _oblique adductor_ muscle of the -great toe and the _transverse adductor_ muscle, more for future use -perhaps than of much present value. Like all apes and monkeys he has -a _peroneus longus_ with its tendon passing across the sole from the -outer border to the base of the great toe and a _peroneus brevis_, both -of them for everting the foot and supinating it. But here again he is -lacking, for he has no little _peroneus tertius_, which Professor Keith -speaks of as a muscle “peculiar to man” and “a special evertor of the -foot”--a muscle passing from the tendons of the _extensors_ of the toes -and inserted into the little toe. He has also the _tibialis anticus_ -and _tibialis posticus_, the latter which flexes the ankle on the leg, -and the former which also flexes it and everts the foot; he has also -the special _extensors_ of the toes. - -This enumeration of the bony, ligamentous, and muscular possessions of -gorilla C. is enough to show that, though he has little of new tools to -make, he has to modify greatly those he has learnt to use so well, so -that one can almost hear him echo the words of David to Saul as to his -new armour. - -The problem of an arch remains to be solved by eversion instead of -inversion of the foot, growth in all directions of the heel-bone, and -the enlargement and straightening of the great toe, and the “setting” -of the foot in a certain degree of pronation and over-extension. - - -Description of the Arch. - -The plantar arch is double, but the longitudinal one must be chiefly -considered here. It lies under the concave roof of the tarsal bones, -seven in number, and the metatarsal bones, and rests in a well-formed -foot in front on the heads of the latter, and behind on the inferior -surface of the heel-bone. The _astragalus_ alone of these bones in -contact with those of the leg, acts like a washer to the ankle joint, -and has no muscles attached to it. Three more of the _tarsal_ bones -need reference: these are the three _wedge-shaped_ bones which have -their bases on the dorsal and their apices directed towards the plantar -surface. With such a set of bony tools as this, all the requisites for -an arch are at hand. Let the half-tree, half-ground walker become a -complete ground-walker, and in the first place the manifest increase of -the action of the flexors of the leg will pull to an unusual extent -on the _tendo achillis_ and heel-bone, leading, in accordance with a -well-known law, to steady enlargement of the parts near to which it is -attached. The greater amount of weight thrown henceforth on the heel -tends in just the same direction, indeed, to general enlargement of the -whole bone. The _astragalus_ being in No Man’s Land, so to speak, takes -less part in the change than any other tarsal bone. The _wedge-shaped_ -bones are exactly so constructed as to retreat a little in a dorsal -direction as the modified walking increases under the action of certain -muscles which will later be mentioned. This, in conjunction with -the projection backwards of the heel and the general growth of the -bone, permits, as far as the bony parts go, a gradual hollowing out -of the originally flat plantar surface, and the increasing eversion -of the foot places more weight on the front pier of the arch, that -is, the heads of the _metatarsal_ bones. The squeezing-up process of -the smaller _tarsal_ bones contributes also to the formation of the -transverse arch. - -The _ligaments_ need no new invention on his part but only a more human -degree of development, and in particular the _calcaneo-navicular_ -ligament and _internal lateral_ of the ankle undergo in the human foot -great development, and the long plantar ligament, originally part of -the tendon of the _gastrocnemius_, comes in to the aid of the arch and -goes to bind it together, so that these humbler structures follow in -the wake of the changing and enlarging bones. - -The plantar fascia, though a powerful protective armour for the deeper -parts of the sole, cannot be held to enter into the formation of the -arch. The _initiative_ in this process lies with the muscles, and, even -if neither gorilla C. himself, nor his descendants, had altered the -muscles of his foot and just given up climbing for walking, there were -muscles strong enough and appropriate for modifying very profoundly his -simian foot, though he might not have arrived at an arch. He or they -might have become long-distance walkers, but never sprinters. - -If the sole of the dissected foot is observed it is seen that the -plantar arch lies approximately over a triangle of which the base is -formed by the _transverse adductor_ muscle of the great toe, across -the heads of the metatarsal bones, and the two sides by the _oblique -adductor_ of the great toe and the _short flexor_ of the little toe. It -extends, of course, somewhat further back under the heel-bone, but this -is its highest part. - -In the changing foot the _tibialis posticus_, which was originally a -flexor of the metatarsal bones, obtains a secondary attachment to -the _scaphoid_ bone, and the _tibialis anticus_ becomes inserted anew -into the internal _wedge-shaped_ and metatarsal bones. “Both of these -muscles, thus modified, help to maintain the arch of the foot. So does -the tarsal part of the tendon of the _tibialis posticus_.” (Keith). - -The three _peronei_ muscles, especially the new _peroneus tertius_, -attached to the little toe, are called in by increased walking to -redress the balance of forces in the foot and produce that eversion, -with some supination, which is essential to the arch. No arch was -possible till these muscles came into some preponderance of action -over the _flexors_, so beloved of gorilla C. The _short flexor of the -digits_ becomes modified so that its attachment to the tendons of the -_long flexors_ in the sole has its _origin_ completely transferred -to the heel-bone in man (Keith). “It can thus act more powerfully in -maintaining the arch,” and finally the _flexor accessorius_, a muscle -which cannot fail to surprise the dissector when he first penetrates -into the deep layer of muscles of the sole, and which is a detached -piece of the _long flexor of the great-toe_, becomes especially -well-developed and helps to maintain the arch. - -The order of events then is: first, increased and altered muscular -function; second, growth of bones and adjustment; third, binding -together of these by new or modified ligaments. If it were possible -to separate in this way the age-long formation of such a living tool -as the human foot, this is the order in which alone, I submit, the -sequence of events can be placed. It is a convenient, because simple -and plain example of initiative in evolution, and I cannot say how much -I owe to Professor Keith’s teaching on the subject.[71] - - [71] It is not sufficiently noticed by some writers how important - is Professor Keith’s teaching as to the maintenance of the arch by - muscular action rather than ligamentous union. And it is a very - practical matter from my own point of view in connection with the - prevention of flat-foot in the young. If indeed the poor deformed - feet of the sufferers can only be corrected by attention to the - lowly-organised ligaments, and the muscles will not avail, I can but - add “God help them!” - - - - -CHAPTER XXII. - -MUSCLES. - - -A work of great value to the biologist has been written by one whose -work has led him in the widening path of human physiology and its very -title is instinct with meaning. The Integrative action of the Nervous -System may not aid the systematist or the student of genetics, but for -insight into formative powers, where the former can but record facts -and find no interpretation, such a work is of supreme importance. -When the plant sealed its fate and enclosed itself in a cell-wall -and abandoned a life of movement, it was foreordained that its rival -would be that cell and its descendants which could adopt a free -life, and that the future of the world would lie at the proud foot -of that conqueror who could command and mobilize the resources of a -nervous system. And, as we know, it has fallen to man to receive the -rewards of this promise and potency of a higher life. If one seeks to -understand the steps by which man has arrived at his primacy it can -only be by the highway of nervous progress, however much the tracing of -certain connecting or collateral paths may throw light on contributing -causes. So that man’s place in Nature is nearly synonymous with the -structural evolution of his brain, as Huxley has shown in his clear and -simple manner. Even if man is to remain still an animal Melchisedec -for generations to come, or to put it lower, a foundling, no future -discoveries that can be imagined will disprove Huxley’s declaration, -“Evolution is no longer an hypothesis, but an historical fact.” And -yet if man has become adapted to his world, and, in it, crowned with -glory and honour by the unfolding of some original complexity, or as -the result of some fortunate mutations in the distant past, the human -brain, with its cranial capacity of nearly three times the number of -cubic centimetres to that of the gorilla, has been making false claims -to a paramountcy over all factors in the wonderful initiative of fresh -capacities and their mobilisation for conquest. Nothing less than such -a “claim” was understood by the ancients, and, though metaphysics -had to supply the lack of anatomy and physiology, it has always been -held that mind was lord of matter, and now scientific research has -told us why. But no one, even the most hard-shelled scholastic, can -refuse to the brain organ its predominant share in the making of man. -This is seen even in the frigid sphere of science by the difference -of interest there is shown between any great discovery bearing on the -evolution of man, or on some new lower animal form. When Sir. H. H. -Johnston astonished zoologists in 1901 by his discovery and proof -of the existence of an archaic large mammal which had been interned -for an incalculable time in the Semliki Forest, the thrill felt at -that historic meeting passed off very soon when the leading British -biologist had monographed the Okapi, settled its name and surname -and introduced it into text-books. This is never the fate of such -as Pithecanthropus or Eoanthropus dawsoni, or of the more recent -genealogical theory and researches as to arboreal man. The call of -these studies of man’s evolution is felt by all, and the difference in -the two branches of biology may account for what must have struck many -others, that is the neglect of adding the blue ribbon of science to the -honours of the discoverer of the Okapi. - -These few trite remarks as to the importance of the nervous system in -the making of man have been introduced here, though they bear more -closely on the next two chapters, because this importance comes in at -every stage of the present treatment of the origin of modifications in -muscle. - - -Anatomists’ Views of Muscles. - -There is a very strict and austere custom among anatomists, which -doubtless is in a measure necessary, of insisting upon following -rigorously the homologies of muscles, especially in human anatomy, -and in this branch of a greater subject the canons are followed to an -extent that surprises the seeker after origins. A remarkable example -of this is in a paper by an eminent anatomist, now Professor at King’s -College, Dr. E. Barclay Smith. It is a paper on the “Morphology of -the short extensor of the human fingers.”[72] He says “the precise -significance of this occasional _extensor brevis digitorum manus_ -is a matter of considerable interest.” He gives four possible -interpretations of this unusual muscle. The last, viz., that it is -derived from a new muscle-germ alone interests us here because of the -remarkable caution and austerity of his remarks on this interpretation. -“If an _ext. brevis dig. manus_ cannot be regarded as an atavistic -anomaly, or as a derivative from any existing musculature, the only -way in which its presence can be accounted for is to suppose that -it is of entirely new origin--the product of a new muscle-germ. -Such an explanation is, of course, the last resort, and all other -possible derivations must be disproved before it can be accepted.” -The physiologist would probably think such an interpretation was -the obviously first resort. The same writer discusses at length the -homology of an exceedingly rare anomaly among muscles, the _extensor -ossis metacarpi hallucis_, and his desire on the one hand to find a -missing parent for Japhet, and his honesty and accuracy on the other -hand lead him to say “even when it is present, it cannot be regarded -as directly atavistic, since it does not represent a normal mammalian -tendency.” And he adds a gentle but remote suggestion--“Brooks -certainly describes such a muscle in _menobranchus_ and _hatteria_--two -rare and remote reptiles!” But, lawful and necessary though this be, -there must be stages on the path of human evolution where such a method -must fail and the anatomists can do no more than hold aloof from theory -or speculation, with a certain grim enjoyment of the disputes and -difficulties of the genealogists. - - [72] Anatomical Society of Great Britain and Ireland, Trans., p. 54. - - -Initiative in Muscles. - -Initiative in the evolution of muscles clearly occurs somewhere in -the stem, and behind the formed expression of an altered habit is the -integrating action of the nervous system. This will be by some looked -at askance as a _deus ex machinâ_ and reckoned as part of the argument -from ignorance in a way which recalls Weismann’s scorn of Lamarckian -factors in germinal selection. I submit that what he and Osborn call -“the unknown factor” of use and habit, arising in response to new -stimuli meets as no other proposed suggestion does the formation of -new muscles. Given a certain fundamental architecture of skeleton and -musculature, such as of primitive vertebrates, one can, without doing -violence to any known facts, place the formation of new organs of -movement in the following order:-- - -1. Neural changes and habits. - -2. Muscular modifications. - -3. Consequent modifications of bone. It carries the question no further -to say that these are correlated, however loose may be the meaning -of that word that is understood. If the prerogatives of Selection -within the germ, of segregation of unit-characters and dominance, -and of mutations are not unlimited in the construction of organisms, -there still remains a sphere of action for the initiating power of -the nervous system. Bones grow and change their form in response to -increased or altered muscular action on them, and it is necessary to -look back a stage further in the story to the neural changes however -produced. There have been abundant opportunities in the long history -of mammalian evolution for primitive forms to take a new course of -life, and they have done so on an extensive scale. The impulses that -have led them may have been started by some “needs” such as Lamarck -taught, some change in their surroundings involving new stimuli, or -“insults,” as Haeckel called them, but the first of the structural -stages must have been in the cerebral cortex. - - -Cross-Roads in Evolution. - -The most instructive levels of animal evolution are those where two or -more great stocks have diverged from a primitive one. There may have -been several factors leading to the division of the early Ungulates -into the odd-toed and even-toed groups, of the Carnivora into cats, -dogs and bears, the Felidæ into the highly-specialised genera of that -intense family, the early parting of gibbons from the common anthropoid -stem, and then the division of this line into the three great genera -with which we are familiar. Whatever may have been the unknown factors -in the environment such as changes of climate and level, geographical -isolation, increase of foes, profusion or lack of food, to which these -diverging stocks became adapted in their organs and form, in fact -whatever we do _not_ know, we know this--that in their measure they -acquired more convoluted and often larger brains, and the stimuli -passing through their receptors into their consciousness increased -with an everflowing tide, in volume, intensity and complexity. Many an -archaic habit of their race they must unlearn, and it is doubtful if -germinal selection would avail in this valuable process of economy as -it is held to do in the case of the human little toe. - -It may be taken as granted that increasing complexity of brain in their -own lines of life did accompany these adventurers of small or large -groups. It follows that muscular changes from the original stock would -follow neural changes, for movement and activity is inseparable from -the animal, and the integrating action of the nervous system would -constantly initiate, maintain and establish fresh habits and these -be expressed in new muscular structure. Whatever higher uses, as we -believe them to be, man makes of his brain, as reflection, reasoning, -imagination and association, such were not the new properties acquired -by these adventurers. They were very much concerned with hunger and -love, and for them “philosophy” did not sustain the structure of -their world. But more varied movements of head, trunk and limbs, and -greater agility and strength brought them such prizes as were within -their reach. This may be only another way of expressing Sir E. Ray -Lankester’s conception of educability, which he maintains to be the -only acquired character the organism inherits, and it may be therefore -assumed to be under the iron law of selection. This must be accepted -with the respect due to the high authority from which it proceeds. But -such a conception, while it removes a false light in certain regions, -sheds no light on the pathway of animal evolution, unless modifications -be transmitted, and we can now take it that man does not inherit the -power to speak which for incalculable ages he has been learning, -nor to write, even though in the days of the early Pyramid-builders -and the Sumerians in the plains of Chaldea they possessed the power -of writing, nor can a musician’s child learn to play an instrument -without teaching, or indeed man perform any of his arts and crafts by -second nature: so, negatively, this knowledge is valuable, and the -neo-Lamarckian must proceed on his quest without anything more than -educability to aid him--but it will serve. The fact is that we do not -inherit habits or associations as such at all, but the neurones of -the grey matter in spine and brain which subserve, direct and control -them. Though a fresh neurone or two in the brain of an early ungulate -deliberating, so to speak, as to the life he shall take up, whether -that of oxen or horses, may be trifling in itself as to immediate value -to the animal, it may be to him as much a matter of fate to acquire -those microscopic cells as it was to the undifferentiated organism -that paused before it sealed its fate as plant. Under the free and -enlightened government of the integrating nervous system liberty to -express itself to an almost unlimited extent, in accordance with -progress, is thus open to the hypothetical adventurers. - -When considering such an aspect of the organism as the “choice” -between the career of an odd-toed or even-toed ungulate, a cat or -dog, a lion or tiger, a gibbon or other of the four anthropoid genera -which assuredly was presented to certain groups of primitive ungulates -carnivores, felidæ or apes, as historical beings, the vision of the -process is sore let and hindered by the limiting force of certain -expressions which have been sanctioned with the _imprimatur_ of fifty -years’ high thinking in the realms of high biology. I refer of course -to the terms Selection and Evolution which, though they cannot be -replaced by better terms, have the power and sometimes have had the -effect of impressing on the story of organic existence an aspect of -_determinism_ which does not allow, for any purposive action of the -individual, the working out of its own salvation, on the part of higher -forms at any rate. As among nations self-expression has become of late -a powerful force in their development, and indeed of individuals, so -it may be argued by analogy that the total experience of an organism, -may result in its co-operation in the process of its progress towards -higher things. Bergson hints at such a process in organisms, but -appears to allow nothing for the individual in his _élan vital_, where -the mass alone counts. So if the two binding terms of Selection and -Evolution must be granted their enormous power over our thoughts, there -must be also a loosing as well as a binding, and we, as well as certain -young ecclesiastics in a hurry, may put in a plea for Life and Liberty. -Thus is Lamarckism immortal, and the integrative action of the nervous -system supplies the reason. - -This well-worn subject is not out of place here, where I am trying to -show evidence of self-expression in terms of muscular modification -arising from fresh activities of the brain. - - -New Muscles. - -If it can be said without fear of question that “the differentiation -of muscle and nerve is the morphological result of division of labour, -whereby the unit of protoplasm, in which irritability and contractility -are combined, has, on the one hand, become modified into muscle, which -retains the property of contractility, and on the other into nerve, -which retains that of irritability,”[73] and if Wolff’s _Law of Bone -Transformation_ teaches that if a normal bone is used in a new way its -structure and form will change to meet its new function, which Sir -Charles Bell had more vaguely taught in 1834, it cannot well be denied -that at certain turning-points in the history of animal organisms the -sequence of changes which arise is neural change, muscular modification -and finally change of bone, whether ungulates, carnivores, felidæ, -gibbons or big anthropoids or man, be the _dramatis personæ_. The only -question is whether selection or use and habit initiates the subtle and -slow process. - - [73] Macalister, _op. cit._, p. 62. - - -Unstriped Muscles. - -The simplest of the muscular acquirements of mammals is of course -that great mass of little structures which constitutes the unstriped -musculature. I must admit that here again I am engaged with what the -professed biologist may call trifles, but these, like some others of -a corresponding rank, have a provoking quality of persistence, and -display, if one may personify them, an insistent desire to know whence -they come and why they are here. Some of these, like the one before -us, may be comprehended in the great chapter of the Evolution of the -Indifferent of which they form a page. This world, at any rate in the -moral sphere, would be an intolerable house of bondage if there were -not many _things that matter not_ as well as _things that matter_, and -there is reason to believe that in the process of the making of man and -a vast number of forms below him there is a large field of structures, -parts and organs, where things that matter not are to be found. One -strange province of this realm is the colouration of animals in certain -regions where no eye ever can see the colour or can take any heed of -the markings, treated very fully many years ago by Mr. Beddard in -_Animal Colouration_. - -Unstriped muscle arises, as the striped variety does, from the -mesoblastic muscle-plate and appears in nearly all organs, -blood-vessels and skin, and as trade is said to follow the flag, so -a development of new unstriped muscles must speedily be found in -every new structure of the regions where unstriped muscle is found. -The skin is the simplest, and less complicated by the presence of -other structures than vessels and organs, where it also exists, but -where it trespasses too much on the territory of selection for my -immediate purpose. A small band of this muscle called an _arrector_, -or _erector_, _pili_ is attached to most, if not all, of the third of -a million hairs which cover the skin of man, and is inserted into that -side of each hair which forms an obtuse angle with the plane of the -skin. This tiny structure is endowed with the quality of contracting -in response to certain stimuli falling on the skin, so that it causes -the hair to which it is attached to stand erect instead of sloping, and -incidentally squeezes some of the secretion out of the sebaceous gland -which lies in each angle. The human skin thus possesses about a third -of a million minute muscular bands and shows no sign of parting with -this old gift from a lower hairy stock, and whatever value, if any, -their function be to their possessor they show a remarkable readiness -to perform it efficiently. It makes their existence and persistence no -clearer to call them vestigial, for one only thus throws the question -of their origin much farther back. Undoubtedly they come from afar -and were in full development in the earliest hair-clad mammals, so an -ancestry reaching back to Monotremes or Marsupials is not to be lightly -set aside. The raw material was undoubtedly formed in response to -stimuli conveyed to the brain, and the earliest appearance of muscles -which erected the hairs must have been wholly insignificant either upon -the survival or comfort of the possessors. - - -A Remarkable Example. - -The _arrectores pili_ exhibit very little evidence of control or -interference from the action of the brain, but there is one region of -one animal, like the Rosetta stone that set Champollion at work, where -a very simple hieroglyph is recorded. I have been able to find no other -in all the hairy mammals I have examined than that startling pattern -which the back of the lion, shown in Fig. 37, sometimes displays. That -well-formed patch of reversed hair of roughly triangular shape which -is frequently found on the back of a lion has been described and, as -I interpret this strange structure, it would seem clear that neural -change in some examples of this species has led to so persistent -contraction of the _arrectores pilorum_ over a certain area of skin, -and that these have permanently reversed the normal and primitive slope -of the hair. I have never found it present in a lioness, and not in -all cases of male lions. It marks its possessor with the brand of a -fierce and especially savage character, and he is not able to screen -it from the eye of the Zoologist as well as Milady did her brand of -shame, until that fatal day when D’Artagnan disclosed it. This pattern -on a lion’s back is strangely reminiscent of the ridge of bristling -hair we see on the corresponding region of a fierce dog’s back when he -is infuriated. In the latter it may be said to have selective value, -as perhaps also is the bristling hair on the head of a gorilla when -enraged, much in the same way as the Chinese warriors sought to alarm -their enemies by terrifying grimaces, or those terrifying tones and -expressions of face which the Tyrant man, really a coward, is said by -such as Miss Wisk to exercise over the women of his circle. We may -present all these to the Pan-Selectionist, but inasmuch as the short, -bristling hairs on the back of a lion are on the one hand hidden by -the mane from an animal in front, and on the other are so small as -to be seen quite close if at all, the survival-value of the reversed -pattern of hair in question is quite outside the province of selection. -It is so manifestly under the control of cerebral action, that it may -be compared, as an undesigned experiment, with that of man in placing -harness upon a horse, as to the power of cerebral action in producing -structure. Though, as far as I can learn, it stands alone, it is -difficult to believe that such a thing as a unique example occurs in -nature, but it is interesting and suggestive from the Lamarckian point -of view, and even the opposing counsel must admit that it is among -indifferent structures. - - -Facial Muscles of Expression. - -This record in terms of hair of personal and ancestral emotions has, -however, a link with certain more numerous and important striated -muscles, such as the facial muscles of man and apes, modifications of -the great platysma-sheet, and which are disposed in two layers, a deep -and a superficial. This covers like a hood at the third month the head -and neck of the embryo, and later assumes on the face its specialised -form of certain bands which operate round the eyes and mouth. As they -are of the striated kind these muscles can be moved at will, but their -main action is much more under the government of the mental processes -of their possessor. As they are fundamentally the same in apes and man -very little new muscular structure arises in man, and little more than -shaping or refining takes place. - -The facial muscles which operate round the orbit have less mental -action represented in them than those of the mouth, though the action -of the special elevator of the upper eyelid is conspicuous among the -expressions of a vigorous person. Both apes and man have muscles on -each side which raise or lower the angles of the mouth, draw the -angles upwards and outwards, and raise the upper and depress the -lower lip; and, though the muscle of the mouth which corresponds -to the _orbicularis_ of the eye is not a continuous structure, but -formed of interrupted bundles of fibres, it is powerful in closing the -lips and active in the expressions. There are also in man scattered -oblique fibres in the substance of the lower lip, well-developed and -closely-set in a sucking child, and these in the adult are scattered -and less conspicuous. - -There is thus a remarkable set of structures in the face of a higher -primate which convey mental emotion. As they also belong to animals -with a high degree of convolution of brain, though certain are found -in lower mammals, their specialisation is only to be accounted for by -the long-continued involuntary expression of mental states existing -in the particular form of primate. Professor Keith says in the work -before referred to: “Muscles supplied by the facial nerve are the -physical basis into which many mental states are reflected, and in -which they are realised. Through them mental conditions are manifested. -It is found that the differentiation of this sheet into well-marked -and separate muscles proceeds _pari passu_ with the development of the -brain. The more highly convoluted the brain of any primate the more -highly specialised are its facial muscles,”[74] and he points out in -a smaller work[75] that in the gibbon, and monkeys of the Old and New -Worlds the facial system becomes simpler and at the same time more -robust, and he pictures the facial muscles as the “servants of the -brain.” - - [74] _Embryology._ - - [75] _The Human Body._ - -If an ape can express a good many of the coarser emotions of an animal -by the action of its facial muscles, and through kindness and training -exhibit some of the finer ones, there is a wide distance between this -level of attainment and the multiplied moods and unnumbered varieties -of expression which give to the human face its unique charm. If we can -express pleasure, pain, anger, contempt, hatred, surprise, affection, -sympathy, fear, hope, reflection, perplexity, gaiety, melancholy, -cunning (and many another can be supplied) what a remarkable field of -physiology in terms of anatomy we have in the facial muscles! There is -a very obvious reason why none of these emotions have been fixed in an -objective form in ape or man, as the patch of reversed hair is on the -back of a lion, for moods and states of feeling in every individual man -are subject to such endless variations that it would be impossible for -them to stamp any individual face with a record of even one emotion -which could be transmitted to descendants, to say nothing of the -inconceivably great probability that heredity would at once swamp any -initial modification. - - -Three Stages. - -The stages then are but three--mental states, specialisation of small -muscular bundles from an existing simple sheet of muscle, and disuse -of the remaining portions, and in this small but highly significant -field we see structures created independently of will as servants of -the brain, and without any survival-value in their earliest stages. -It is more than likely no monkey, ape, or early man whose face was -covered with thick hair from his eyes downwards, ever saved his life -or gained a better mate by reason of the subtle modification of a tiny -muscle which was proceeding _pari passu_ with the growing complexity -of his convolutions and their manifested emotions. This is not to -claim that a more modern man or woman would not find sexual selection -of value by reason of his or her more pleasing or commanding facial -expression. That the initiative of these alluring modifications was -simple and Lamarckian cannot be gainsaid, whatever the fruit of the -finished process may be to-day. We know in our own experience that many -a handsome person with good features and little expression is often -unsuccessful in the matrimonial market, when another with defective -features and a fine, delicate, attractive expression takes the prize. -So the early story of the formation of muscles of expression is seen to -be a page in the evolution of the indifferent. - - -The Fly-shaker Muscle. - -The panniculus carnosus, of which the facial muscles are part, is a -great system of musculature found in various animal forms, and it -furnishes a field for study of the evolution of the indifferent and the -initial stages of the formation of a muscle. This is a servant of the -brain in a more indirect manner than the facial muscles, but it, too, -arises in obedience to the integrative action of the brain. The early -specialisation of it need not be considered here. It may be considered -unwarrantable to claim the great Fly-shaker muscle of Ungulates as an -indifferent structure, but the arguments by which the Pan-Selectionist -would annex it to his sceptre, as a triumph of the minute care of the -organism by selection, rest only on the assumption that he knows how -it has become an adaptation to the life of its possessors. This is -now more than it used to be a matter of opinion since the publication -of Professor Bateson’s revolutionary _Materials_, and others beside -he have reserved to themselves the liberty of doubting the accepted -explanations by the tangled path of adaptation. The statement of -Weismann, “Everything is adapted in animated nature” was necessary -to his theory of germinal selection, but it admits of extensive and -numerous exceptions in view of the fact that so much of adaptation is -partial and imperfect. If he had said that _every organism_ as a being -is adapted he would have been nearer the truth, but that every tissue -and part of an organism is adapted is demonstrably untrue. A large -number of organisms, themselves apparently well adapted, flourish well -enough and reproduce their kind in spite of faulty and rudimentary -tissues and parts. If it were not so we should have seen little of -progress except what come under the laws of genetics,--a distributional -matter. Even the super-Geddes could not distribute what was not there, -for he could not deal with raw materials and change them by a fairy -wand into manufactured articles. In the great field of domesticated -plants and animals man has to find not only some mutation or some -dominant strain and breed it to his will, but to cultivate the domestic -qualities of animals and employ cultural conditions for plants. There -is doubt expressed as to the length of time or numbers of generations -during which these cultural conditions can extend, but Professor -Thiselton Dyer many years ago made the remarkable statement as to -plants:--“While specific stability under constant conditions appears -to be the rule in nature, it is widely different in cultivation. When -a plant is brought under cultural conditions it maintains its type for -some time unaltered, then gives way and becomes practically plastic. -From my experience at Kew, where I saw the process continually going -on, I hazarded the generalisation that any species, annually reproduced -from seed, could be broken down in five years. During that period -specific stability, though menaced, tends to maintain itself. Darwin -was well aware of this.”[76] - - [76] _Nature_, November 28th, 1907, p. 78. - -Most biologists from time to time betray the fact that their minds can -only be relieved from an intolerable burden, in accounting for the -numberless adaptations in organisms, by the view that many of them -originate through factors of use and stimuli from environment, and -at first are entirely indifferent as regards the survival or better -mating of their possessors. To which the stern opponent replies, “What -is there to show that in the existing scheme of things there is any -provision made which will minister relief to the burden of your little -mind?” To which, “answer came there none,” except a subdued reflection -that everything we see of living, striving nature around us has a -most provoking way of speaking to us of daily, hourly and incessant -action and reaction, stimulus and response, and that those who view the -process thus do seem to bring some order into what would otherwise be -chaos--and yet all the while someone is being grossly deceived! This -“may be magnificent but it is not proof,” some will say, and will ask -if the older observers of the heavenly bodies were not wrong in their -complete conviction that the sun went round the earth. This digression -introduces the role of the fly-shaker. If I am told that this muscular -sheet in a cow or horse to-day is a relic of raw material inherited -from a remote ungulate stock little evolved, and that it contributes in -hot weather in the time of flies to the comfort and better mental state -of the cow or horse, that it shall be able to keep those enemies at -bay, and that the muscle is kept well in order by two or three months’ -practice in each year I can understand in a measure its presence -to-day. It has an efficient ally in the sweeping tail of a cow and -that of a wild horse, and both of these weapons are further aided by -the mobile ears of cow and horse, and the stretching movements of its -head and neck. Thus the body of a cow, for example, is like a map with -four territories delimited, that of the fly-shaker, the tail, the ears -and the head and neck. Between these offensive weapons a cow is better -defended against flies than a European in India by his punkah, or China -was by its great wall, or Britain by the wall of _Vallum_ of Hadrian -or the wall of Severus, which with forts and garrisons was designed -to protect it. Speaking in allegory the evolving brain of an early -ungulate occupies the position of an ancient Chinese Emperor or a Roman -Proconsul in Britain in its provision against “barbarians,” either -Asiatic or Celtic. The resemblance goes further, for no experienced -Roman General, whatever the Celestial minds in China may have thought, -would fear that the loss of a sector of his wall would imperil the army -of occupation in Britain or the fabric of the Roman Empire. But as, in -the long run it contributes to one’s welfare to be comfortable, and -even the domestic ungulate is somewhat of a hedonist, a well-developed -fly-shaker is maintained, the occasional use of which in winter and -frequent use in summer and the active purposeful switching of tail, -twitching of ears and jerking of head have their limited value. Here -there is ample room for diverse opinion and the opponent will ask -with some degree of force how we know that there is no more benefit -to the cow from its fly-shaker than a mild degree of comfort, and may -assert that the possession and use of it may have survival-value by its -defence against deadly parasites. We do not know, nor does he, but it -would seem that except for the tsetse fly in Africa the plague of flies -does little to an ungulate beyond irritating its brain, and if he had -no fly-shaker, he would still be able to reach a considerable distance -with his tail, ears and head over the irritated regions. The question -of survival indeed resolves itself into the vigour and energy of his -integrating brain. - -To this view of the function and origin of the panniculus carnosus the -busy systematist and student of genetics may refuse to listen, and pass -to the order of the day, but I submit that in stating a position it is -useful to put forward a crude example in which the issue is plain, and -which subsumes an immense number of smaller and more subtle cases, and -in a region where the most hardy rebel will not dispute altogether the -sway of _personal_ selection. It is a question here of the manner in -which, speaking in metaphor, the early ungulate first set about making -his eolithic or palæolithic weapons and fashioned them into what we see -to-day. “Forged by the incident of use” and habit meets the story of -the fly-shaker far better than some mutation arising in far back ages -or some dominant variation, or “useful variation within the germ.” At -any rate Lamarck finds the raw material to hand, and there are supplied -adequate noci-cipient stimuli with response, in regions where these are -most active under the dominating action of the brain. - - -Other Muscles. - -In the skeletal muscles of the primates many muscles offer themselves -for consideration as examples of inherited structures arising under -the stimuli of altered function, and only a few of these will be dealt -with. It might appear sufficient to those who yield, perhaps too -willingly, to authority, if I were here to try and prove my point by -quoting the statements of one of the greatest anatomists of our time -and country, and so pass on--but it is to be feared authority cannot -carry one far in a dispute so important. Macalister says, however, “The -anatomical arrangement of the muscular system is the physical exponent -of habitual actions and those actions are the chief factors in moulding -the bones and in regulating the position of the somato-pleural vessels -and nerves”--and “the locomotory function and consequent utility of the -trunk-muscles were lost when the early vertebrates became terrestrial. -In higher vertebrates, and notably in man, the mobility of several -regions of the vertebral column differs both in degree and kind: the -outgrowing vertebrate processes show consequent variations, and _the -muscular system is varied accordingly_.”[77] Also “as both origins -and insertions (of muscles) are the creatures of habit, they are both -equally variable with variation of function; but, as in higher animals -the kind of work to be done is more constant than its degree, so, -as a rule, insertions alter less than origins.”[78] Macalister, at -any rate, held a very clear dynamical rather than static view of the -making of the muscular system. But as the days of authority are in a -certain sense gone for ever, and we live under the reign of experiment, -research and questioning, every biologist, within certain limits, does -what is right in his own eyes; there is no King in these days. - - [77] _Op. cit._, p. 71. (Italics not in original.) - - [78] _Op. cit._, p. 73. - -Skeletal muscles are structures in which, if ever, the factors of use -and habit and disuse would be shown, because muscle is a tissue, with -highly active metabolism, so that it has been called “an expensive -tissue” for the animal to maintain. - - -Muscles of Primates. - -This physiological fact agrees with the anatomical results of an -extended study in the musculature of primates, especially of man, and -Hartmann’s book on Anthropoid Apes supplies abundant evidence of the -variations of the muscles of these animals, which are not at all more -striking than their differing modes of life would suggest. It would be -wearisome to quote all these, but a single muscle may be given as an -example of a special ape’s muscle with variable distribution. It is -called _latissimo-condyloideus_ and starts from the insertion of the -_latissimus dorsi_ and passes along the inner aspect of the humerus -for a variable distance. In the _baboon_ and others it goes to be -inserted into the inner inter-muscular septum and the internal condyle -of the humerus, in the _orang_ to the condyle, and in the _gibbon_ to -the centre of the shaft. As to origin it proceeds from the insertion of -the _latissimus dorsi_, but in the _gorilla_ from the coracoid process -of the scapula and from two portions of the _pectoralis minor_, and is -finally attached to the inter-muscular septum between the _brachialis -anticus_ and the _triceps_; in the _chimpanzee_ it divides into an -anterior and posterior portion, the former being attached to the inner -condyle, the latter to the middle and inner head of the _triceps_; -in the _orang_ it divides similarly, but in one particular example -it had an anterior thin portion attached by a slender tendon to the -coracoid process of the scapula and a posterior portion arose from the -_latissimus dorsi_; in the _white-handed gibbon_ it arose from the -function of tendons from the _latissimus dorsi_ and _teres major_ and -was inserted into the fascia between the tendon of the _biceps_ and the -_brachialis anticus_. - -Such a divergence as this within the strict limits of an anthropoid -muscle, concerned in the various forms of climbing action of these -apes, can only suggest an origin from a divergent set of functions and -small details in their respective modes of climbing. - - -Hand and Foot of Man. - -Both the hand and foot of man supply a small muscle for consideration -in the present connection of habit with formation of new structure. -If man be regarded as of simian origin there are not as many entirely -new muscles in his equipment as would be expected from his departure -from the habits of simian ancestors, though many muscles are found to -be altered in size and shifted from the ancestral positions. But the -human hand presents one suggestive example of a little muscle not found -in any other animal, the special small extensor of the thumb, arising -from the interosseous membrane between the radius and ulna, and from -the radius, being segmented off from the _extensor of the metacarpal of -the thumb_, and it accompanies this muscle and tendon to be inserted -into the first phalanx of the thumb, and is peculiar to man. It can be -easily seen at the radial border of the well-known “snuff-box” which is -produced by it when it is fully extended. This is of course a muscle of -small importance to the functions of the hand, and its appearance in -man can only be supposed to be a subordinate detail easily derived from -the _greater extensor_ by reason of the more delicate adjustment to -complicated movements of the hand under the directing power of higher -cerebral development. - - -Peroneus Tertius. - -The foot of man possesses the small _peroneus tertius_ which was -referred to as one of the evertors of the foot concerned in the -construction of his plantar arch. Macalister and Professor Keith both -speak of it as peculiar to man, and the latter refers to it at some -length,[79] the whole passage being worth quoting here. “Although -the evolution of the human method of progression was attended by a -profound alteration in the form and action of every muscle and bone -with lower limbs, yet this great transformation was produced without -the appearance of any really new element. One new muscle--the _peroneus -tertius_--did appear, and the history of its evolution throws an -interesting sidelight on the origin of new structures. It arises by -the outer fibres of the common extensor muscles of the toes being -separated. In all the anthropoids the feet are so articulated at the -ankle-joints that the soles are directed towards each other, and only -the outer edge of the foot comes to rest on the ground when the animal -tries to stand. The feet have a tendency to assume a similar position -in children at birth. The advantage of a muscle, such as the _peroneus -tertius_, is apparent in the human foot, for it tends to raise the -outer border of the foot, so that the sole is properly applied to the -ground. If we examine the muscles which, rising from the front of -the leg, cross the ankle-joint to end on the back of the foot on the -toes of fifty men, we shall find every stage in the evolution of this -muscle. In one man at least it will be undeveloped; in two or perhaps -three it will be represented by a part of the tendon of the extensor -muscle of the little toe, which in place of ending entirely on the -toe sends a part to end on the metatarsal bone of the little toe. In -only forty of the fifty men will the _peroneus tertius_ be found quite -isolated from the parent muscle--_the extensor communis digitorum_, and -to have a distinct origin from the fibula in the leg, and a separate -insertion to the base of the fifth metatarsal bone in the foot. In a -series of fifty specimens every stage in the isolation of this new -muscle will be seen. It has never been found in any anthropoid, and is -more often absent or undeveloped in African than European races.” - - [79] _The Human Body_, p. 92. - -To this excellent account I have only to add one comment. It can -hardly be an accident or without significance that this special human -evertor of the foot concerned in the construction of the plantar arch -is “often absent or undeveloped” in African races, which are well-known -in some groups to have adapted themselves to a form of foot which shows -no plantar arch, being normally flat-footed. In this small field of -observation, a mere plot of lentils like that which Shammah defended of -old, there is set forth a mimic battlefield, and it is not difficult -to see that the forces at work can owe allegiance to one and one only -of various commanders. The problem as to the origin of the _peroneus -tertius_ would no more attract the Mendelian than did the trousseau -and approaching marriage of Caddie Jellyby attract the far-away gaze -of her mother, fixed upon the world of Borria-boula-gha, and, for that -matter, de Vries would hardly pay it more attention--to him it would -be indifferent; whereas Weismann would have as much to say about it -as about the little toe of man, which furnished for him and Herbert -Spencer such fruitful material for debate many years ago. This muscle -resembles the results of some of Michael Angelo’s first attempts at -sculpture, thrown aside perhaps in his place of work and from time to -time taken up, rough-hewn again and again and finally shaped into a -form far from perfect, but with the value and teaching of a failure -for him who was some day to outshine all modern rivals. If the history -of this muscle be not one of initiative in evolution through the -factor of use and habit the Pan-Selectionist must do the best he can -with an incalculable number of “trials and errors,” and must suppose -that, rather than allow this small territory to the neo-Lamarckian, a -long series of man’s ancestors have been making experiments for the -benefit of man’s walking power under the guidance of selection with -an insignificant muscle whose only function is that of aiding in the -eversion of the foot, and that in the rudimentary condition described -by Professor Keith it had selective value. No one who was not committed -to a dominating theory could hesitate for a moment which of the two -alternative views of the origin of the _peroneus tertius_ he would -choose. Dr. Barclay Smith speaks in the paper referred to above of the -_extensor brevis pollicis_, or _minor_, as a muscle of extremely late -appearance, and as “peculiarly human,” and says all the evidence points -to its being a segmentation product of the _extensor ossis metacarpi -pollicis_, its appearance being foreshadowed in the anthropoid by an -extension of that muscle on to the proximal phalanx of the thumb. - -It is not without interest to the thesis before us to read the rather -bewildering story of the early life of a very insignificant muscle such -as the small extensor of the thumb of man. - -As illustrations of the moulding and pruning of perfected muscles it -may be remembered that, as Macalister says, “portions of muscles may -also become detached and degenerated so as to act as ligaments,” and -“the adult muscular system of man bears everywhere traces of earlier -cleavings and subsequent fusions, partial disappearances and local -outgrowths.”[80] This passage recalls one in which Huxley says in -watching certain phases of development you can almost see the hidden -artist at work, and here the sculptor may be pictured in his chipping, -trimming, rejecting and finally shaping, some creation of his brain; -and from a biological point of view a vision of the processes of use -and disuse may be obtained. Professor Keith also speaks often of the -migrations of muscular attachments in a way which agrees with the -passage quoted from Macalister. - - [80] _Op. cit._, p. 73 - - - - -CHAPTER XXIII. - -INNERVATION OF THE HUMAN SKIN. - - -For at least seventy years the surface of the human skin has been -the subject of so much physiological observation and experiment that -Professor Sherrington considers the literature connected with it to -be probably greater than in any other branch of physiology. Most of -this study centres round the skin as a receptive field and problems of -the nervous system. It is easy to see why this should be in the case -of an organ so great as the skin, covering all the other structures -and organs and exposed through ages of evolution to the vicissitudes -of an inconceivable number of stimuli. And one outcome of this study -is to show that, metaphorically speaking, the skin is a mosaic, and -not the confused and blurred production of a child of four years old -who has been given a sheet of paper and a paint-box. There is order -in this field, and even without calling in final causes, plan and -purpose. Beside the protective function exercised by the skin it plays -a large part, through its nervous endowment, in the processes by which -the brain is made aware of the surrounding phenomena, thus conveying -intelligence to the centre of life only less important than that of the -special senses. It is maintained here that the result of the various -physical stimuli, of which pain, cold, warmth and touch are the chief, -is that certain functions and structures of the skin have arisen in -response to them. - -This is, no doubt, to beg the question of origin, and if the balance of -evidence be seen to be against this view the order of events would need -to be stated differently. But the position is clear, whether correct -or not, and if it be shown to be erroneous it will at least have good -“lighthouse value.” - - -Observed Facts. - -Briefly stated the facts of the innervation of the skin are of two -orders, anatomical and physiological; the former examined by the aid -of the microscope, the latter by physiological experiments of a varied -kind. The chief aspect in which these are viewed here is the mode of -distribution of these two groups of fact, and it is held that this -strongly suggests without proving it, the alleged mode of origin of -both. - - -TABLE I.--_Distribution of Touch Corpuscles_:-- - - In the deep connective tissue of the dermis there are:-- - In the thumb about 70. - " " index finger 105. - " " middle finger 60. - " " whole hand 500. - They are numerous over finger joints and front of elbow joint. - In all 530 about the joints of the upper extremity. - 317 about those of the lower extremity. - -TABLE II.--(_From Schäfer’s Text Book of Physiology_):-- - - Average of Meissner’s corpuscles to each square millimetre, which is - approximately one five hundredth part of a square inch:-- - - Palmar surface of distal phalanx of index finger 21 - Palmar surface of second phalanx of index finger 8 - Palmar surface of first phalanx of index finger 4 - Palmar surface of metacarpus of little finger 2 - Plantar surface of distal phalanx of great toe 7 - Middle of sole of foot 2 - Flexor surface of forearm in each sq. mm. 1 - Distal end of flexor surface of forearm in each sq. mm.:-- - 1 to each 6 sq. mm. approximately. - - * Absent from the cornea, and conjunctiva of the upper eyelid and - from the glans penis. - - -TABLE III.--_Distribution of Touch Spots_:-- - - These must be distinguished, of course, from the touch _corpuscles_ - of the preceding list and the subjective element in the study of them - must be borne in mind. - - If an area, as of the calf of the leg, be prepared, by cutting short - the small hairs, and examined, it is found that there are about 15 - touch spots in each square centimetre, which is about one-fifth of a - square inch. - - In another area so treated the hairs are counted and the following - result is given:-- - - 1. On the dorsal surface of the forearm 78 touch spots are found in - an area containing 15 hairs. - - 2. On the flexor surface of the forearm 147 touch spots are found in - an area containing 22 hairs. - - 3. On the scalp 66 touch spots are found in an area containing 38 - hairs. - - Schäfer says: “An area of the dorsum of the distal phalanx of a - finger contains about seven times as many touch spots as an equal - area between the shoulders. Regions poor in touch spots are the - flexor surface of the upper arm, the upper third of the thigh, the - leg above the inner malleolus, the neck, and in general the skin over - subcutaneous surfaces of bone.”[81] - - [81] Schäfer’s _Text-Book of Physiology_. - -TABLE IV.--_Distribution of Cold and Warmth Sensations._ - - The Scale includes twelve grades of sensation in cold, and eight in - warmth sensations, and commences with the regions which yield the - maximal intensity of sensation. - - _Cold Sensations._ - - 1. Tips of fingers and toes, malleoli, ankle. - - 2. Other regions of digits, tip of nose, olecranon. - - 3. Chin, palm, gums, glabella (a small central area just above bridge - of nose). - - 4. Occiput, patella, wrist. - - 5. Clavicle, neck, forehead, tongue. - - 6. Buttock, upper eyelid. - - 7. Lower eyelid, popliteal space, sole, cheek. - - 8. Inner aspect of thigh, arm above elbow. - - 9. Intercostal spaces along region of axillary line. - - 10. Areola of mamma. - - 11. Nipple, flank. - - 12. Certain areas of loins and abdomen. - - _Warmth Sensations._ - - Absent from lower gums, mucosa of cheek at second lower molar and - cornea. - - 1. Tips of fingers and toes, cavity of mouth, conjunctiva, patella. - - 2. Remaining surfaces of digits, middle of forehead, olecranon. - - 3. Glabella, chin, clavicle. - - 4. Palm, buttock, popliteal space. - - 5. Neck. - - 6. Back. - - 7. Lower eyelid, cheek. - - 8. Nipple, loin. - - -TABLE V.--_Distribution of Cold and Warmth Spots._ - - By stimulation of cold or warmth spots there is shown, not only - the quality and quantity of the stimulus, but the locality. When - punctiform stimuli are applied to pairs of cold spots and pairs of - warmth spots marked “local sign” is found. This Goldscheider showed - to be higher for cold than warmth spots. - - Cold Spots. Warmth Spots - Palm .8 mm. Do. 2 mm. - Cheek, Chin and - forehead 0.8 mm. Do. 5.0 mm. - Upper arm 2 mm. Do. 3 mm. - Back of hand, leg, - thigh 3 mm. Do. 4 mm. - Forearm 3 mm. Do. 3 mm. - Back, chest, abdomen 2 mm. Do. 5 mm. - - Thus on the palm of the hand two pairs of cold spots .8 mm. apart - are distinguished by this punctiform stimulation, whereas on this - surface two pairs of warmth spots are only distinguished when they - are 2 mm. apart on the cheek, chin or forehead and cold spots are - distinguished when .8 mm. apart on the same surfaces warmth spots - when 5 mm. apart. - - -TABLE VI.--Average lowest distances in millimetres on different areas - of skin where two points are felt as two or minimal distances from - which double sensation is obtained. - - Skin Region. Adult Man. Boy aged Twelve. - Tip of tongue 1.1 1.1 - Palmar surface of tip of - finger (index) 2.3 1.7 - Red surface of lip 4.5 3.9 - Palmar surface of 2nd - phalanx of finger 4.5 3.9 - Dorsal surface of 3rd phalanx - of finger 6.8 4.5 - Side of tongue 9.0 6.8 - Tongue 27 mm. from tip 9.0 6.8 - Plantar surface of distal - phalanx of great toe 11.3 6.8 - Surface of palm of hand 11.3 9.0 - Dorsal surface 2nd phalanx - of finger 11.3 9.0 - Forehead 22.6 18.0 - Back of ankle 22.6 20.3 - Back of hand 31.6 22.6 - Forearm and leg 40.6 36.1 - Dorsal surface of foot 40.6 36.1 - Surface on outer border of - sternum 45.1 38.8 - Back of neck 54.1 36.1 - Middle of back 67.1 31.6 to 40.6 - Upper arm and thigh 67.1 31.6 to 40.6 - - -TABLE VII.--(_According to Weber’s Law._) Average differences in - different regions of skin of sensation of pressure. - - Forehead } - Lips } - Dorsum of tongue } 1/30 to 1/40 - Cheeks } - Temple } - - Finger nail } - Dorsal surface of forearm, leg, } - and thigh } - Dorsal surface of hand } - Dorsal surface of 1st and 2nd } 1/10 to 1/20 - phalanges of fingers } - Palmar surface of finger } - Palmar surface of hand } - Flexor surface of forearm } - - Dorsum of foot } - Dorsal surface of toes } - Plantar surface of toes } More than 1/10 - Sole of foot } - Surface of leg and thigh } - - Thus on the forehead differences of pressure are distinguished when - they are increased by 1/30, whereas on the dorsum of the foot they - have to be increased by 1/10 to be distinguished. This is carried out - by impact of little balls of a light substances such as pith. - - -It may be remarked of these tabulated results that on the one hand -they are the results of work extending over some seventy years and -numerous observers, and on the other that, broadly looked at, _they all -tell the same story_ of stimuli in their incidence on the skin--those -of pain, cold, warmth and touch. There is also one thread of origin -running through all, and that is that the regions most exposed to the -four stimuli show the highest development of specialised function and -structure. - - -Some Aspects of the Nervous System. - -It has been said with some truth that the telephone has struck a -mortal blow at such serenity of life as the Juggernaut Car of modern -progress has left us. But if it has done nothing else it has furnished -the physiologist with a good illustration when he sets out to expound -the functions and arrangement of the elements of the central nervous -system and its peripheral expansion. In addition to this general -light upon a great matter the vivid experience of many an Englishman -during the recent years of war adds point to a subordinate phase of -the general story of the telephone, for it represents my contention -as to the origin or initiative of the sensorial areas of the mosaic -under consideration. Modern persons may be divided into two classes, -those who want and those who do not want the telephone, and the former -may be sub-divided into A, those who can, and B those who cannot -get it (or could not). A and B from the present point of view may -be termed Receptors, though to call the B people by that name is to -speak Hibernically. With this war-time experience in our minds, we -may picture a vast period of time during which the stimuli of pain, -cold, warmth and touch were hammering on the skin both before it -began to lose its chief hairy covering, and after that process had -left man still a hairy animal, but with much-diminished amount of his -ancient heritage. These stimuli fell upon the skin very much as the -class A, among telephone receptors, spent numerous fruitless stimuli -on Postmasters-General, Ministers in Parliament and in “short” bitter -letters to our bright little _Daily Pope_, and who yet found themselves -not “connected up,” as the saying goes. There is no knowing how long -it was before they had enough effect on the delicate nerve fibrils -struggling up into the epidermis and produced receptors or were -“connected up” to the exchange or central nervous system. I am inclined -to liken the pain stimuli to the short letters referred to, the cold -and warmth stimuli to those addressed to the Postmasters-General and -the touch stimuli to those which fell upon Ministers at question time. - -Another comparison of the peripheral portion of the nervous system to -common things has at times forced itself upon my mind when reflecting -on the stimuli which are continually assaulting the skin, as I have -watched on the Needles’ Downs a flock of sheep on a summer evening -returning to their fold. As the sun begins to set they are scattered -over the western end of the Downs, still cropping the short grass -clothing those chalk and flint slopes which from immemorial time has -alone flourished there. They wander singly or in small groups on such -parts of the slope as the intrusive golfer still allows, and gradually -fall into larger groups which follow somewhat indefinite paths. As -they move further and further towards home they are seen to follow -one another in single file on some score or more of clearer paths, -and finally converge into one well-beaten and broad path until they -descend the northern slope and pass out by a single roadway into which -a gate opens, and so reach the haven where they would be. Here one has -a simple picture of the common stimuli of the skin, at first indefinite -and ineffectual, by their cumulative action producing an individual -receptor and its nerve connection with the central system. - -Professor Leonard Hill[82] also gives a view of the general action of -the nervous system and compares it to control of the police force. He -supposes a murder to have been committed in a village, and that the -local policeman telegraphs to the local town ordering the roads to -be searched. The policeman is the tactile sense-organ, the telegraph -wire is the sensory nerve, the telegraph office in the local town -is the spinal cord, from this office a message is sent to the town -police-station by another wire and the police are set in motion. The -police are the muscles, the wire that sets them in motion in the motor -nerve. The message is also sent to neighbouring towns and to London, -that is to say, other local offices (parts of the spinal cord) and the -head office (the brain) are informed of the crime or sensory impulse. -The central office in London directs the operations controlling the -local police office. The whole order of events need not be here -described because it goes beyond my immediate purpose, but it is enough -to say that attached to the head office are the cleverest detectives -(higher sense-organs) and in these are kept records of past crimes, -lines of action of the police, and success or non-success of their -investigations. - - [82] _Manual of Human Physiology._ Leonard Hill, p. 369. - -Following on this picture he speaks of the way in which conscious -actions become automatic and makes a statement to the effect that -“_There is evidence to show that the axons_ (or processes of the -nerve-cells which extend unbroken from nerve-cell to its termination) -_become covered with a adulated coat as each new tract is formed. Thus -the structure, like the habit, becomes fixed_”--and--“_It would appear -as if, by repeated experiences, tracts and pathways must be beaten -through the nervous system_”[83] (Italics not in original). - - [83] _Op. cit._, p. 371. - -Beside this I place a statement from Professor Graham Kerr as to his -view of the development of peripheral nerve-trunks. He is reviewing -the “outgrowth” theory of His, the “chain cell” theory of Balfour, and -the “Primitive Continuity” theory of Hensen, and expresses himself as -follows: “_It is suggested that the development of the actual nerve -fibril is simply the coming into view of a pathway produced by the -repeated passage of nerve impulses over a given route._”[84] (Italics -not in original.) - - [84] _Text Book of Embryology._ Vertebrata with the exception of - Mammalia. Vol. II., 1919, p. 106. - -A passage from Professor McDougall’s _Physiological Psychology_ may -also be referred to at more length than it was in Chapter III., -page 25. Speaking of the automatization of voluntarily acquired actions -which have been explained by the view that purely reflex actions -carried out by mechanisms of the spinal level were also originally -acquired by our original ancestors as voluntary actions, he says, “This -view is usually associated with the name of Wundt, who has forcibly -advocated it. It implies, of course, the assumption that acquired -characters are in some degree transmitted from one generation to -another, a proposition which most biologists at the present time are -inclined to deny because they cannot conceive how such transmissions -can be effected. Nevertheless, the rejection of this view leaves -us with insuperable difficulties when we attempt to account for -the evolution of the nervous system, and there are no established -facts with which it is incompatible. If, therefore, we accept this -view we shall regard the congenital neural dispositions, both those -that determine pure reflexes and those that determine instinctive -actions, as having been acquired and consolidated under the guidance -of individual experience, with the co-operation, to a degree which we -cannot determine, of natural selection.”[85] - - [85] _Physiological Psychology._ W. McDougall, p. 156 (1911). - -These three statements from a physiologist, a zoologist, and a -psychologist, all of great eminence, though they differ in particular -problems studied, tell very strongly in favour of the position here put -forward as to initiative in the production of specialised innervation -of the skin. - - -Origin of Cold, Warm, Pain and Touch Spots. - -The hair-clad skin of primitive man provided ample raw material for -the eventual differentiation of both end-organs and sensorial areas -which is found to-day. Not only did he possess what is called Common -Sensation in his skin but in the individual hairs lay a delicate -tactile structure, which, though probably inferior in delicacy, serves -a similar purpose to that of the vibrissæ on the muzzle of Felidæ. Each -hair, being deeply inserted into the skin and supplied with fine nerve -fibrils, when it is bent, acts as a lever communicating an impulse -to an afferent nerve trunk In an animal covered with thick hair the -sensory impulse conveyed might be exceedingly delicate, but, from the -nature of the case, of much more limited range than in one like man in -whom the hair is so greatly diminished in length and thickness. - -It would be fruitless to speculate as to which of these four forms of -stimuli was the earliest to become effective in developing man. - - -Cold and Pain. - -Two of them, cold and pain, may be termed _nocuous_; one, that of -touch, _useful_, and one, that of warmth, _indifferent_. If it be true, -as Professor Scott Elliott states,[86] that man’s earliest home had a -climate which “lies between the regular tropical, with wet, steaming, -impassable jungles, and the colder temperate zone, so affording chance -of acclimatisation in both directions,” the stimuli of cold would even -then not be wanting, however much they increased in severity when he -passed through glacial periods; but wherever, whenever, and at whatever -time he first became man he had to tread the Via Dolorosa in the course -of his hard and eventful life, and must have been well accustomed in -all regions of his skin to the stimuli of pain, working, as he did, for -his living, and fighting for it and his mate, with varied and powerful -enemies. Though it is correct to call both these fundamental stimuli -“nocuous,” this is all a matter of degree, and both the stimulus of -moderate cold, raising blood-pressure and activating metabolism, and -that of minor pains, would do little else than good in his education -for the higher terrestrial life to which he had descended. If he was -to learn effectually to take care of himself the discipline of both -moderate cold and pain would be as valuable to him then as in its -measure it is to his descendant to-day. The triumphs of medicine and -surgery could never have appeared if it were not for the beneficent -warning voice of pain that so generally accompanies disease. - - [86] _Prehistoric Man and His Story_, p. 92. - -Through long ages of exposure to the stimuli of cold and pain came -response in the form of cold and pain spots, after minute struggles -between the static conservative tissues of the skin and the dynamic -force of repeated assaults upon them. In due time then receptors -appeared and each became connected with the central organs, by which -means better adapted motor reactions against “nocuous” cold and pain -became possible. In 1900 Professor Sherrington summed up the evidence -in Schafer’s work on Physiology against the existence “of separate -afferent fibres with their specific end-organs entrusted specifically -with carrying painful impressions to a pain centre,” but Professor -Starling in his later work on Human Physiology speaks of “a distinct -sense of pain,” probably subserved by a distinct set of nerve fibres, -but for the present purpose it is not necessary that agreement on such -a problem should be reached, for it is alone with pain _spots_ that we -are concerned. He also points out that on the one hand the cornea is -sensitive to only one of the four stimuli in question, that is, pain, -and on the other that the surface of the glans penis is sensitive to -cold and pain, but tactile sensation and warmth sensations are almost -entirely absent. - -_Touch._--This form of stimulus and its response can only be reckoned -as useful to the organism, except that it may be, and often must be -indifferent. The great number of the touch spots can be understood -when it is declared by Professor Sherrington that almost invariably -there are one or more touch spots close to the emergence of each -hair,[87] and that they are very numerous also on the palmar and -plantar surfaces of the hand and foot. Of the four forms of cutaneous -stimuli those of touch are the only kind that have so far been proved -to have specialised corpuscles, the other three having developed the -physiological equivalent of cold, pain and warmth _spots_. - - [87] _Schafer_, p. 922. - -_Warmth spots_ are decidedly the least numerous of the four, those of -pain being, as stated by Professor Sherrington, the most numerous. It -is obvious that unless thermal stimuli become somewhat excessive they -hardly can be described as “stimuli,” being more or less neutral in -their action on a warm-blooded animal. This cannot be entirely so, -because it has been shown quite conclusively that warmth spots _do_ -exist, though much less numerous than others. There is a significant -fact as to thermal reaction and that is that there are no pure -_heat_ spots like those of cold, for the stimuli of about 49° C -are so associated with those of pain that warmth spots alone are -distinguished, and among primitive man no stimuli of heat could impinge -on his skin, until he had learned the use of fire, more powerful than -those of solar heat. - -Such stimuli of heat as the rays of the sun would occasionally -discharge on the skin would resolve themselves into the general -stimulus of pain, and in this direction a far shorter initiation -occurred than with any of the four normal cutaneous stimuli. The fact, -at any rate, of there being no _heat_ spots is to be noted. - -It remains now, having quoted three writers eminent in physiology, -psychology and zoology in support of the modest thesis here put -forward for me to appeal to the authority of the facts contained in the -tables for such evidence as they can give, and to give a summary of -this. - - -Summary. - -1. Table I. shows that the structures known as touch corpuscles are -distributed on those parts of the skin where the stimuli of touch fall -most and in proportion to the degree in which those parts are employed -in tactile discrimination; thus, most of all on the index finger (with -the exception of the tip of the tongue) next on the thumb and less on -the middle finger. There are 530 of these corpuscles to the upper and -317 to the lower extremity. - -2. Table II. bears out the same conclusion, the average number of -corpuscles to a square millimetre being twenty-one on the terminal, -eight on the second and four on the first phalanges of the index -finger, whereas on the foot there are seven on the great toe much -exposed to stimuli and only two on the middle of the sole of the -foot, which is little exposed. The absence of them from the cornea -and conjunctiva, protected by quick and powerful reflexes from such -stimuli, and from the (normally) covered glans penis is in accordance -with the other results. - -3. Table III. dealing with touch spots, shows that these are nearly -twice as numerous on the flexor as the dorsal surface of the forearm; -and nearly five times as numerous as on the scalp, where tactile -stimuli are few, and that the distal phalanx of a finger contains about -seven times as many as an area between the shoulders. The regions poor -in touch spots are shown to be those where relatively few tactile -stimuli can fall. - -4. Table IV. gives cold and warmth sensations graded according to the -delicacy with which they are perceived in many regions of the skin. -The cold sensations are best distinguished on the parts normally most -exposed to cold, as the tips of fingers, malleoli, tip of nose, chin, -patella, wrist, and least on the protected areas, inner side of thigh, -flank, loins and abdomen. The warmth sensations are best distinguished -on the regions on which the stimuli of warmth has most frequently -fallen, tips of fingers and toes, cavity of mouth, palm of hand, less -so on the neck and loin. And the striking fact is noted that warmth -sensations are not felt in the lower gums, the inside of the cheek at -a certain level and the cornea, which again is protected from these -stimuli by its efficient reflex, whereas to the gums and inside of the -cheek most warmth stimuli have not been “stimuli” at all. - -5. Table V. also gives results of the mode of distribution of cold -and warmth spots, examined with punctiform stimuli. The “local sign” -for cold is higher than that for warmth spots, and two of these -are distinguished as double when only 0.8 millimetres apart on the -palm, cheek, chin and forehead, whereas on the upper arm, back and -thigh, they are only distinguished as double when separated by two -millimetres, and this distance is the minimum at which warmth spots are -distinguished as two, that is 2 mm. on the palm, and five on cheek, -chin, forehead and back. This tells the same story as Table IV., of -past stimuli of cold and warmth. - -6. Table VI. deals more elaborately than the others with double -sensation in different areas of the skin, the tip of the tongue being -the most accurate in this respect of all examined, and the tip of the -index finger next, which is to the great toe as 2.3 to 11.3, the palmar -surface of a finger half as accurate again as the dorsal surface, the -palm of the hand twice as accurate as the surfaces of the forehead and -back of ankle, nearly four times as much so as the dorsum of the foot -and six times as the skin of the middle of the back. - -There is here a very close relation between the amount of exposure of -these various regions to tactile stimuli and their present equipment of -ability to discriminate between two small objects. - -7. Table VII. deals with the sensation of pressure in certain groups of -areas, and shows that change of pressure is perceived about three or -four times as accurately on the forehead, lips and tongue, as on the -finger nail, back of forearm, hand, or fingers, and more than three or -four times on the back of the foot, and sole, and surface of leg and -thigh. In this group of observations also the rule is followed that -the greater and more frequent in man’s ancestral past have been the -exposure of his skin to variations of pressure, the greater is his -present power of accurate discrimination of them. - -There are some scattered facts mentioned by Professor Sherrington -which are in keeping with the line here taken, that the formation of -receptors in the skin have their origin in accumulated stimuli. He -refers to the vain endeavours of Goltz to evoke the reflex croak of -the female frog by applying electrical stimuli to the skin, whereas -non-nocuous mechanical stimuli were the only stimuli that proved -effective. - -He never was able to elicit the “extensor thrust” in the “spinal dog” -by any form of _electrical_ stimulation, but only by a particular kind -of mechanical stimulus. This peculiarity was also found in the pinna -reflex of the cat. - -As to the scratch reflex in the dog it was only when it was _easily -elicitable_ that it could be evoked by electrical stimulation as well -as mechanical, and when it was not easily elicitable electrical stimuli -failed altogether while mechanical stimuli still evoked it. - -He describes the receptor as a mechanism “_attuned_ to respond -specially to a certain one or ones of the agencies that act as stimuli -to the body,” and points to the fact that _electrical_ stimuli are -not of common occurrence in nature and no chance for adaptation to -evolve in the organism receptors appropriate for such stimuli has -been afforded. Such negative facts are at the least suggestive in -considering the question of the mode of origin of receptors and -end-organs, electrical stimuli being rare in nature. - -The subject of the innervation of the skin and its receptors has been -treated here in a great measure by the aid of imagination, with some -evidence, and a good deal of reconstruction has been attempted, but -perhaps this will be pardoned by those who are prepared to carry out -a corresponding process with such as Pithecanthropus, Eoanthropus and -Saurian monsters from somewhat scanty osseous remains. Any biological -theory of the origin of these receptors than the one here put forward -is faced with some formidable difficulties, which are probably -insurmountable. - - - - -CHAPTER XXIV. - -THE BUILDING OF REFLEX ARCS. - - -Assuming the foregoing origin of the innervation of the skin, I submit -that between this rudimentary process and the building of sensori-motor -arcs in the spinal cord and brain there is a field, almost unlimited, -for initiative in the construction of new forms of animal life. The -former is nothing without the latter. To leave it without proceeding -further is to leave it “in the air” as military writers say. The -formation of Receptors, then, both in the skin field and in the higher -sense-organs, leads of necessity to the formation, multiplication and -co-ordination of reflex arcs. As in an imperfectly organised telephone -service after many a repeated stimuli or “rings” the messages begin to -reach their destinations, and as by practice the operators better and -better learn their business, so the impulses passing through receptors -and nerve-fibrils become organized into more or less efficient systems -of arcs, and response is secured to them by some effector of gland or -muscle. It is not true of man alone that practice makes perfect. - -A certain feature of higher animals which distinguishes them from lower -must be remembered, and that is that among them the individual becomes -increasingly important. Speaking generally, the latter are born and die -in large groups, and their lives resemble those of their group more -closely than in the former. The struggle of the individual is vividly -pictured by Professor Woods Jones in his description of the baby of the -perfected arboreal animals. He shows how they and the roaming Ungulates -and Pelagic Cetacea cannot indulge in large families, and that it is -only those forms which have a safe retreat for their young which can -avoid reduction of the size of their families, and how the higher apes -still more resemble in these respects mankind, as we know it. For -the proper study of the “synthesis of the individual” organism this -essential fact must be kept in mind. - - -Some Illustrations. - -It will be expected of course that for the claim here advanced on -behalf of the predominant influence of the nervous system in the -initiative of the evolutionary process some experimental or other -evidence should be produced. Before entering upon this, I think some -analogous facts from the story of man, in accordance with the principle -laid down in the first chapter should be stated, so as to illustrate -the line of thought. These will be in the nature of analogies, and -whether or not the accepted accounts of the chosen examples agree -precisely with the last word of the critics is immaterial, for if not -they will equally well serve the purpose of illustration. - - -Abraham. - -When from his Mesopotamian home an opulent and successful farmer -decided for reasons sufficient to himself that he would leave his -present prosperity for a promised land, and went out not knowing -whither he went, it is manifest that the construction and organization -of Abraham’s cerebral cortex was the motive power which led to this -step so fraught with change to himself, his descendants, and the -world. By his choice he showed the inherited structure of his brain, -its nature, and perhaps its nurture, to be different from those of his -family and tribe. Implicit in this venture was the introduction of a -new group of people into a new environment, and their reaction to it -through many generations is written before our eyes to-day in indelible -characters. It was neither stature, muscular development, colour of -hair, skin or eyes, properties of digestive or circulatory organs, -keenness of sight, hearing, taste, smell, or touch which led to this -result even though without a high degree of efficiency of these he -could never have “arrived” as he did. - - -Mohammed. - -The conjunction of environment with a certain organized complexity of -grey matter was hardly ever more important to the world than that of -Mohammed. The powerful frame, abundant black hair, wonderful dark eyes, -and great imposing head may well have attracted the rich widow who -“made his fortune” by marrying him, and they stood him in good stead in -his later adventurous career. But nothing short of a unique arrangement -of his reflex-arcs, chiefly in the association-areas of his brain, -could have opened up to him the world of Asia and Europe. - - -Columbus. - -Who can doubt that it was ultimately to the inherited structure of the -convolutions of his brain that Columbus owed his great achievement -in opening up a New World; or that to the reactionary and intense -“character” of Philip’s brain the persecutions in the Netherlands were -due; and on the other hand that to the brain of William of Orange -with its liberal and enlightened “character” the Seven Provinces that -resisted Philip owed their freedom; the results in the two cases being -the decay of Spain from that time forward, and the final success in -the struggle for religious liberty. In such a view of historical facts -it is not necessary either to follow Carlyle in his extreme claims for -the influence of great men and heroes, nor to look upon the hero as an -epiphenomenon. It is certain that eventually some other great man would -have arisen to do what the great Genoese did, if he had not done it, -and as it is claimed that Amerigo di Vespucci did, and it is certain -that Philip was only the last of the Hapsburg sovereigns who determined -the fall of Spain, and that Huss, Jerome, Wycliffe and Luther in their -days initiated the struggle for religious liberty which Holland brought -to success. But the facts referred to can hardly be disputed, and the -men and their “characters” did certainly determine permanent changes in -the world. - - -Napoleon. - -Among individual men of modern times none strikes the imagination -as does Napoleon. Without ignoring the tremendous outburst of the -soul of down-trodden France at the Revolution, it cannot be denied -that the “character” or grey matter of brain of the man of whom it -is said “nothing where he had passed was as it had been before,” was -the dominant and natural fact that changed the face of Europe. What -physical quality had Napoleon, except those of his grey cells, which -could have led him to such results on the environment into which he was -cast? - - -Migrations. - -Similar results in nations and tribes can easily be supplied from -the great migrations of the past. The wider movements are but due to -comparatively small aggregates of adventurous men, in other words to -the aggregation of many similar central nervous systems. The great -Western and Southern adventures of the Scythian Tribes had many -contributing causes on which the historian has much to say, and they -were physically highly efficient for their new career, but, reduced -to the simplest elements, it was neither their great stature, strong -muscles, flaxen hair, nor blue eyes, but the cerebral constitution of -a comparatively small group of them which brought part of the nation -to the promised land, and left another and large part in their homes -beyond and along the Danube. The subsequent story of the latter may -well be compared with the invaders of Gaul and Italy in connection with -initiative in evolution. - -The successive invasion of Britain by Low German tribes in the fifth -century, and the Scandinavian hordes of Swedes, Danes, Norwegians, -Letts and Finns in the eighth and ninth teach the same lesson. The -later condition and development of the Northmen in France, Italy, -Spain, Sicily and Britain have only to be compared for a moment with -that of their races who remained in Norway, Sweden and Denmark and -their descendants, to bring clearly before one’s mind the profound -influence exerted by the cerebral constitution of the original Viking -hosts on their career in their new environments, and, indeed, on the -environments themselves; as in intermarriage with their conquered foes. - -These examples have been chosen for the reason that one feature is -common to them all, the introduction of an individual or group into -new environments by reason of the constitution of their brains, -irrespective of the contributing factors. If these be sound analogies -they bear closely on the matter of initiative in the evolution of new -forms of life. The men in question came to their task, in their day, -with a certain equipment of brain derived from many ancestors and much -nurture. Unconscious arbiters of their fate and that of multitudes who -should follow them, they initiated a course of physical and cerebral -evolution of which we can see much revealed before our eyes. The motive -power of their conduct bears a relation to their physical forms that -the engines of a motor-car do to its varied forms of body. The latter -are modified indefinitely to suit convenience, comfort and grace, but -fundamentally they exist and are energised by the former, just as -structure is modified for the performance of function. - -This fact is occasionally brought vividly to the mind of an observer -when he first passes a Rolls-Royce car in all its glory and -magnificence, and then a rough squalid kind of trolly in which the -engine-parts of a similar future Rolls-Royce are out for trial. In -principle it is not a long step from these illustrations to the diverse -environments of animals in which their lot is cast, and their reaction -to them as to behaviour and structural change. - - -Some Changes in Habits of Man. - -There are two current views as to the present erect posture of man, -one which traces it to the adoption of a new posture by a pronograde -four-footed ancestor, and the other that man’s ancestors were “never -typically pronograde with four supporting limbs,” but derived from an -arboreal stock in which the forelimbs were mobile rather than stable. -Whenever or wherever man became orthograde he opened up for himself -and his descendants immense regions of structural and functional -change and became increasingly dominant over his environment. Changes -in muscles, joints, bones, bursæ, lungs, heart, and vessels occurred -through his employing in new modes the muscles, joints, bones, bursæ, -lungs, heart and vessels he already possessed, and the resemblance -between these structures of man and the great apes has given to the -latter the name of anthropoid, and this similarity of structures -in the highest Primates has done much to support in the past that -Simian origin of man which is at present questioned. The behaviour -of the apes and early man were sufficiently alike to lead either to -a parallel or genetic similarity. This point is, perhaps, irrelevant -in considering the great field for initiative in the formation of -new physical characters, and chief among these new reflex-arcs which -have built up the marvellous organ of man’s glory and greatness; but -no one can dispute the elementary fact that the ancestor of man who -adopted terrestrial bipedal locomotion and became orthograde, owed it -to his growing brain and the higher integration of his organs for that -function. But besides the new posture he had adopted he learned to talk -articulately, to make tools, and to use stereoscopic vision. None of -these could have been started on the upward way without a long process -of trial and error in the course of his total experience and practice -of his powers. The results that followed from these three properties of -his are inconceivably great, and it is unnecessary to enlarge on such a -theme or to add to the number of examples. - -Leaving, then, the immediate ancestor to work out his own destiny in -his new terrestrial home, we must as before proceed backward in the -history of animal life in the line of Primate ancestry. - - -Primate Ancestry. - -It is generally agreed to trace the Primates back to an active pioneer -animal form which took to the trees, and which arose out of the -widely-spread Insectivores. This derivation will probably satisfy -any reasonable genealogist. But, if we may use a parallel in human -families, this active animal was as different from its congeners as -Napoleon was from his four brothers who played a part in European -history, and it is not necessary to say more as to the significance of -this fact than that the relative importance of “chassis” and “body” is -again a useful analogy. But we need to ask what those congeners did -if we are to succeed in understanding the Napoleon-like course of him -who became our Primate ancestor. From the original widely-spread and -plastic raw material of the Insectivores allied forms took different -lines, and their stories are written at great length in one small -and the three other great orders of Bats, Carnivores, Ungulates, and -Rodents. As it has been pointed out, Carnivores took to attacking -larger prey, including their less fortunate relatives, and stepped -into the arena as carnivorous animals; the Ungulates-to-be became -herbivorous and developed into two great groups of hoofed animals, -relying mainly on flight for safety; Rodents took to burrows for -defence, ceased to trouble much about attack, and became gnawing -animals; Bats adopted an aerial life--a poor form of it indeed like -that of the aeroplane--and acquired a degraded fore-limb. Before -leaving these great orders of animals, whom I do not desire to compare -unfavourably with poor Louis, Jerome, Joseph or Lucien Bonaparte, it is -convenient here to refer to a fact which comes to light immediately one -looks into such a piece of classification as this of the orders arising -out of the loins of the early Insectivores, and that is the functional -conception underlying it. Doubtless pure functional “characters” -could never supply a whole system of classification in the light of -the modern doctrine of descent with modification, and of zoological -affinities. This is shown in a change from division of six orders of -Birds-Running, Swimming, Wading, Climbing, Predatory and Perching -Birds, to that of a few old-fashioned Ratite Birds, and all the rest, -one which seems the best that can be offered at present. - - -Insects, Mollusca, Birds. - -The grouping of animals by structural characters, and by affinities -which are assumed, though based on almost undeniable evidence, whether -into species, families, classes, phyla or sub-phyla, has its apotheosis -in Mollusca and Insects. As to the second of these immense groups -it has always seemed strange that their colourings and structural -characters should have received such intensive study from Weismann to -the exclusion of Mollusca, when he set out to prove his stupendous -negative, and still more that of Vertebrates, among which his chief -difficulty and desired triumph would seem to have lain. Mollusca though -invertebrate are held by many to be in the line of ancestry of the -highest forms of life, and at any rate insects are not. They are most -fruitful fields indeed in which Nature has been able to show what she -could do by her stern selective powers, but, from the point of view of -descent with modification, may be fairly compared to a review of an -army in time of peace, or the Kriegspiel of a German military staff. He -who concerns himself with the fundamental difficulties of the problems -at issue in evolution must make his notes of what experts tell him of -such groups as those of Insects, Mollusca and Birds, and pass on to the -higher forms in which on the one hand function becomes the predominant -partner, and on the other individual experience becomes more and more -important. He feels indeed at liberty to wish the entomologist and -ornithologist all success, and to leave him at peace, in his siding, to -pursue his delightful and interminable studies far from the dust and -din of controversy. - - -Insectivores. - -The critical territory of vertebrate, and still more of Mammalian -forms, in which the genealogist pictures the five main groups of -Insectivores, looking about them, if one may so speak, in the world -around and pondering which of many paths they shall pursue, resembles -certain centres that may be seen in towns where three, four, five, -or seven different roads are open to the traveller, each with its -incalculable effects on his ultimate career. If one may change here the -metaphor it may be said that the Insectivores are the watershed of the -Five Rivers of higher life. However much the wayfaring insect-feeders -have diverged from this broad centre in structure, and however much -the laws of genetics have widened this divergence, the facts of -function stare one in the face when such descriptions of three of the -four orders outside the Primate stock are pondered--Flesh-feeders, -Herbivorous animals, Burrowers and Gnawers. These time-honoured names -appealed strongly to older zoologists, and in them is implicit a large -body of evidence for initiative in their evolution by pioneering work -on the part of their ancestors. Though in these days Prototheria -include Monotremes, One-vent animals, Metatheria, Marsupials or pouched -animals, and Eutheria Insect-feeders, and though Mammals derive -their indispensable name from the function by which they feed their -young, the most severe of systematists cannot clear his mind from -the old leaven of function in all these terms. They imply momentous -potentialities prior to new structures, and the modern fails to ban -entirely such functional names. I believe there is here no juggling -with names and words on my part, but a stone in the foundation of the -unambitious building which I am seeking to rear. It is ultimately -connected with a directive power as well as the formation of -sensori-motor arcs in the central nervous system. - -Is it possible or probable that the factors which led some group to the -water alone, some to a life in water and on land at different parts -of their lives, some to a crawling life on land and partly in water, -some to the air and trees, some to nocturnal, some to hybernating, some -to burrowing life, some to a diet of flesh, some to one of plants, -some to the trees alone, some to the trees and land, some to the -land by night and trees by day, and some for ever and wholly to the -land--is it probable that any process of selection of suited structures -with countless ages of trial and error, could have determined these -changes of habit and habitat? At least one may claim that the balance -of probabilities is heavily against that view, and that the forging -of reflex-arcs, with all it means to the career of an individual, -affords a more intelligible hypothesis, and that this is strongly -supported by modern discoveries and doctrines arising from the work of -physiologists, as will appear later. - - -The Place of the Nervous System in Evolution. - -The constitution of the nervous system is conditioned by conduction, -its fundamental and primary function. Its processes consist in the -transmission of impulses from receptive fields to effective reactions -through devious paths in a region which, even to-day, is a jungle, with -many further secrets for physiology to reveal. From this point of view -the nervous system may be looked at as a clearing-house and storehouse -of impulses _on their way in_, _on their way through_, and _on their -way out_. If so, the making of new reflex-arcs is a process which has -gone on simultaneously with the formation of receptors in the skin, -the higher sense-organs and such deep structures as muscles, and that -of effectors of infinite variety--and these are called conveniently -adaptations. When we hear from Professor Sherrington that the afferent -fibres with their private paths which enter the spinal cord outnumber -three times those which leave it, and that those of the cranial nerves -should be added, so that the afferent fibres may be reckoned as five -times more numerous than the efferent, we get a vivid idea of the -fundamental importance of the formation and compounding of reflex-arcs -into systems. Without that the most sensitive receptors and the widest -range of structures and organs, small and great, would be as nothing -and things of naught. - -A neurone is the anatomical, as the reflex-arc is the functional unit -of a central nervous system. Just as it is profitless to consider apart -the engines and body of a motor car, as working machine, so is it to -picture neurones and reflex-arcs separately in the living nervous -system except for the purpose of an ideal construction. In common with -the organs and structures of higher animals they have to pass, as -historical structures, through the stages of initiation, repetition -of rudimentary function, and selection by trial and error, till the -“canalizing force of habit” issues in rudimentary and increasingly -efficient effectors. It is in this final stage where the triumphs of -selection have been won, and where their undeniable value and interest -has led some exponents of the distributional laws of genetics to -disregard, or accept as data, the early and formative stages. Theirs -is a mental state which resembles that of Darwin, who, for once in a -moment of haste, declared the question of the origin of life to be -rubbish. - -In the foregoing consideration of the formation of receptors of the -skin it was assumed that certain common stimuli of the environment -hammer out for themselves paths in the nerve-fibrils of the skin and -by ceaseless repetition lay down not only the receptor, which may -be called the _terminus a quo_, but also the afferent fibres which -ultimately find their way into the grey matter of the cord and brain. -That this is the initial stage of the construction of the higher -nervous system can hardly be denied. But it carries the problem of the -synthesis of the organism but a little way unless it be coincident -with the construction of new reflex-arcs and their co-ordination -into systems. Till this stage be reached in a rudimentary form the -most cunning and exact adaptations and structures, or, as they may -be broadly called effectors, will not advance the efficiency of the -organism in the smallest degree. If the receptor be the _terminus -a quo_ the effector is the _terminus ad quem_. This is so obvious -that it may be waved aside as a truism not worth the notice of a -zoologist concerned with the major problems of biology. It may seem to -challenge in a highly speculative region and manner the labours of the -biometrician and Mendelian, but, if fairly met it no more encroaches -on their territory than do the labours of the engineers who invented -the first and crudest chassis of a motor car upon the elaborate and -brilliant ingenuity, taste and skill of the coachbuilders who turn -out the “body” of a sumptuous Rolls-Royce of 1920. But the latter -would never have “arrived” if the former had not made his slow and -arduous trials and errors and final success. So here, as in many other -subjects, a truism has its use. If the biometrician and Mendelian will -only abstain from erecting notice-boards to proclaim “No thoroughfare -here,” we shall not be put down as trespassers or poachers on their -ground and may range at large in certain fields of speculation. - - -Some Neural Phenomena. - -Among numerous phenomena of nervous reactions discovered by the -research of physiologists certain have a close bearing on the formation -of receptors, afferent fibres and reflex-arcs, especially those -of Delay, Summation, Fatigue, Block or Resistance, Localization, -Facilitation and Inhibition. - - -Facilitation. - -But of all these important reactions in nervous tissues none bears -so closely on the problem of the formation of reflex-arcs as that of -Facilitation. This is equivalent to the Law of Neural Habit of the -physiological psychologist, and is bound up with the highly important -Law of Forward Direction, which Professor Starling says might as well -be spoken of as the Irreciprocal conduction of nerve-arcs. The Law of -Forward Direction of sensori-motor arcs is too well known to need here -any description. But when this law is taken into account the phenomenon -of Facilitation is seen to throw a strong light upon the earliest -and rudimentary formation of specialized nerve-fibres, reflex-arcs -and Final Common Paths leading to the effector glands or muscles. -Facilitation is described shortly by Professor Starling as follows. -If the passage of a nervous impulse across a synapse or series of -synapses in the central nervous system be too often repeated, fatigue -is produced, and there is an increase of the block at each synapse. -If, however the stimulus be not excessive and the impulse not too -frequently evoked, the effect of a passage of an impulse once is to -diminish the resistance, so that a second application of the stimulus -provokes the reaction more easily, and he adds that the result of -summation of stimuli is in fact in the direction of removal of block. -When an impulse has passed once through a certain set of neurones to -the exclusion of others it will tend, other things being equal, to -take the same course on a future occasion, and each time it traverses -this path the resistance in the path will be smaller. Education then -is the laying down of nerve-channels in the central nervous system, -while still plastic, by this process of Facilitation along fit paths, -combined with inhibition (by pain) in the other unfit paths. He makes -the important statement that Facilitation is of great interest in -connection with the development of “long paths” in the central nervous -system and, _more especially with the acquirement of new reactions by -the higher animals_. (Italics not in the original). - - -Raw Materials of the Central Nervous System. - -The raw materials of higher central nervous systems are furnished -even in lowly Vertebrates by the neurones and their processes, and -the pathways into the grey matter by the “canalizing force of habit” -in the receptors and afferent fibres. Facilitation, discovered in -higher Vertebrates, such as dogs and cats, throws backwards a light on -the earliest struggles towards success and integration among phyla, -sub-phyla and smaller groups, and here again the well-known may lead -to the less-known. We may then frame a legitimate hypothesis, or at -least an ideal construction of trials and errors and success, if those -of lower levels were ever to be introduced to the career of progress -and achievement. But to make good this claim it is necessary that it -be based on the important doctrine taught by Hughlings Jackson of the -three (or more) levels of sensori-motor arcs--those of the spinal or -lowest, of the sensory or intermediate, and those of the third or -highest level, in which the association-areas of the Primate brain are -at once the means and the title to his primacy, or headship of the -sentient world. The light of this doctrine guides the mind backwards to -the frog-stage of animal evolution with its highly organized congenital -system of arcs of the spinal level, so efficient for its life that, -even when the brain is removed, the frog can execute under certain -stimuli a purposeful complicated movement such as that of trying to -wipe away with its foot an irritant drop of acid applied to its head -or back; or, still more, if touched lightly between the scapulæ, will -“lower its head at the first touch, and again more so at a second, -and at a third will, besides lowering the head, draw the front half -of its trunk slightly backwards; at a fourth the same movement with -stronger retraction; at a fifth give an ineffectual sweep with its -hind or fore-foot; at a sixth a stronger sweep; at a seventh a feeble -jump; at an eighth a free jump, and so on.” Probably such an animal as -the frog has all its reflexes congenitally organized, whereas a dog, -reaching the sensory level, has added countless reflex-arcs to those -inherited from its early ancestors of the Insectivores which had long -emerged from the spinal level, retaining its old, perfecting its new -inheritance, and eliminating the unfit. Perhaps a faint picture of this -long process may be afforded by watching an experienced mountain guide -ascending an ice-slope with the aid of ice-axe, hand and foot. - - -Integration of Raw Materials. - -Every group of animals in the higher ranks has its own entailed -property of innate reflexes, for example, the reflexes which subserve -the reflex functions of the cord: those of locomotion, muscular and -vascular tone, micturition, defæcation, impregnation and parturition. -These exist in an animal of the spinal level whether or not it -remains purely aquatic, partly aquatic, partly terrestrial, arboreal -or terrestrial. As the progressive groups ascend the ladder of life -they add to this inalienable heritage, gained we need not here ask -how, fresh reflex-arcs by response to new initial stimuli, forging -them by the incident of use. So, the original acquirements in the -past levels serve as starting points for raising the degree of their -nervous integration with growing control over their environments. The -long story from the simple central nervous system of a fish, with -a few or no association-areas, to that of man with his extensive -frontal, parietal, parieto-occipital association-areas, could never be -deciphered, even with the light of the laws of genetics turned on full, -without a protracted process of construction of fresh arcs. A common -illustration of such a series of changes and results may be seen in the -building of a house. Bricks, foundation-stones, walls and a roof may -serve some of the elementary requirements of a house and much less than -these were of use to early man for his shelter. Without them we cannot -call any structure a modern house; but also without floors, staircases, -windows, chimneys, division into rooms, some degree of decoration by -paint or paper, and a supply of water, we should refuse in these days -the name of house to that rough structure, apart from beauty of design, -decoration, within and without, and some addition of modern appliances -of comfort and convenience. In the history of house-building the stages -of supply of raw materials, adaptation to needs guided by selection, -initiation, trial and error have their counterpart in the construction -of higher animals. - - -Evidence. - -It will be asked what evidence there is for the view here put forward -that such is the order and method of the construction of the central -nervous system. There are two classes of evidence. The first direct, -and the second indirect and resting on inference. The well-known leads -to the less-known and inferred. Direct evidence of the foundation -of new reflex-arcs and their organization is of course small. The -conditions, such as the duration of human life, preclude any extensive -formation under experiment of new reflex-arcs, but enough is known to -enable one to follow the backward way with some confidence. As to the -inheritance of these, the evidence rests on opinion and tremendous -probability, but as the only problem with which I am concerned here -is that of initiative I think it better to leave the matter of -transmission to a dispassionate consideration of the probability of its -occurrence. - - -Direct Evidence. - -The prolonged researches of over twelve years of Professor Pawlow and -his colleagues on dogs afford a body of evidence as to the possibility -of producing new reflexes in the life of an individual which have -never been questioned. In 1913 at Groningen, before the International -Congress of Physiologists, he gave a brief account of this work. His -previous work on the digestive glands carried on by delicate operations -in which the œsophagus was diverted from the stomach and made to open -externally, and in which a portion of the stomach was diverted from the -rest and a new “small stomach” was formed, gave him the opportunity -of immensely important insight into the factors governing the work of -the various glands of the stomach. The work of others showed similar -results in the pancreas. I only refer to these because they lead up to -the special artificial results with new reflexes which he described in -1913. He states that the nervous system besides the primitive function -of reproducing innate reflexes, possesses another prime function-namely -the formation of new reflexes; and that the living thing is enabled -to respond, by definite and suitable activities to agencies to which -it was formerly indifferent. His experiments on the formation of -“conditional reflexes,” as he calls them rather than “acquired” as -opposed to “innate,” are grouped around the feeding of the animal -and mainly deal with the salivary glands, because they are in direct -connection with the external world and their reactions are simply and -easily observed. An indifferent stimulus is chosen for the reflexes -which it is desired to build up, and this is applied at the same time -as food or acid is introduced in the mouth. After a few sittings it -is found that this indifferent stimulus _alone_ is now capable of -calling forth a secretion of saliva. “The conditional reflex has been -formed; the formerly indifferent stimulus has now found a path to the -requisite part of the central nervous system. The reflex-arc has now -a different afferent neurone.” He gives a good example of this in the -result of the application of painful stimuli by a strong electrical -current to the skin, systematically accompanying each feeding of the -animal. He finds that the strongest electrical stimuli applied to the -skin give rise merely to the “feeding reaction,” that is, the secretion -of saliva, and no indications of any fright or pain appear. “The skin -of a dog can be subjected to cutting, pinching or burning, and the -only result we shall obtain will be the manifestation of what, judging -from our own experience, we should call the symptoms of the keenest -appetite; the animal follows the experimenter about, licks himself, -and saliva flows in abundance.” This, it must be remembered, occurs in -the absence of the offer or sight of food, _at the time in question_. -He adds: “In this way we have been able to divert the impulses from -one path to another according to the conditions, and we cannot avoid -the conclusion that the diversion of an impulse from one path to -another represents one of the most important functions of the highest -parts of the central nervous system.” The presence of certain special -conditions, he points out, causes the indifferent stimulus, which would -otherwise be dispersed in the higher centres, to be directed to a -particular focus, and _eventually to lay down for itself a path to that -part_. A very interesting detail of such a building of a new reflex is -that “the stimuli from which the new reflex is to be worked out shall -be rigidly isolated.” Therefore to avoid any interference with the -certainty of the experiment, such matters as a personal bodily odour -or kind of movement, or even such a slight fact as a change in the -mode of breathing familiar to the dog on the part of the experimenter, -has in the latest experiments been removed by the application of the -stimuli by mechanical devices worked from another room, with results -similar to the earlier ones. Conditional reflexes can also be obtained -from stimuli arising from the locomotor apparatus, as the joints, -eliminating the stimuli arising from the skin. Also certain parts of -the frontal lobes were extirpated and “when one part is extirpated -the reflex is obtained from the flexion of the joint, but not from -the skin; if a different part be removed we can get the skin-reflex, -but not the reflex from the joint.” He extirpated in one case the -greater portion of the posterior part of the brain and the dog lived -for several years after this in complete health. It was found easy to -obtain a conditional reflex for various intensities of illumination, -also for sound, and even a fine differentiation of tones. In another -dog the anterior half of the brain was removed and all the reflexes -before worked out in this animal disappeared, and yet in this helpless -condition of the dog he could train it to give that response of the -salivary glands which he called the “water-reflex,” in which first of -all an irritating acid was introduced into the mouth and the subsequent -administration of water provoked an abundant secretion of saliva which -does not occur when water is poured into the mouth of a normal dog. -This was confirmed in another example in which alone the centre for -smell had been spared, and yet it was possible in it to train the -smell-reflexes also. I add one striking sentence from Pawlow’s address -which, though an opinion, must be received with the respect it deserves -from such a source. “It is perhaps not rash to think that some of the -newly-formed conditional reflexes can be transmitted hereditarily and -become unconditional thereby.” - - -Indirect Evidence. - -From these limited but cogent pieces of evidence I turn to the -larger but confirmatory lines of indirect evidence and inference, of -which such works as those of Professors Sherrington, Bayliss, and -Starling, the notable address of Professor Macdonald at Portsmouth -in 1911, as well as the recent work of Professor Woods Jones on -Arboreal Man, are full. Indeed if the construction of new reflexes -and reflex-arcs in organic evolution “forged by an incident of use” -as Professor Macdonald puts it, were expunged from these works, their -treatment of the physiology of the central nervous system of higher -animals would be emasculated, to say the least of it. And yet not -one of these eminent men is writing _ad hoc_, or for the confusion -of Weismann and his followers. At this point it may perhaps gain for -the remaining pages a little more consideration from opponents if I -give a few quotations from these writers in support of the foregoing -statement--perhaps the breeze of authority may then carry my little -bark a little further on its perilous voyage. Professor Sherrington -remarks on the first page of his well known work, in reference to the -cell-theory, “with the progress of natural knowledge, biology has -passed beyond the confines of the study of merely visible form, and -is turning more and more to the subtle and deeper sciences that are -branches of energetics. The cell-theory and the doctrine of evolution -find their scope more and more, therefore, in the problems of function, -and have become more and more identified with the aim and incorporated -among the methods of physiology.” Again, “Mere experience can apart -from reason mould nervous reactions in so far as they are plastic. -The ‘bahnung’ (or facilitation) of a reflex exhibits this in germ.” -He uses more than once the pregnant phrase, “The canalizing force of -habit”; again, “Progress of knowledge in regard to the nervous system -has been indissolubly linked with the determination of function in -it.” Speaking of the receptive-field he says of the central nervous -system, “To analyse its action we turn to the receptor organs, for to -them is traceable the initiation of the reactions of the centres”; -of the extero-ceptive field he says, “facing outwards on the general -environment it feels and has felt for countless ages the full stream of -the varied agencies for ever pouring upon it from the external world,” -page 20, and “each animal has experience only of those qualities of -the environment which as stimuli excite its receptors, it analyses -its environment in terms of them exclusively. The integration of the -animal associated with these leading segments can be briefly with -partial justice expressed by saying that the rest of the animal, so far -as its motor machinery goes, is but the servant, of them. Volitional -movements can certainly become involuntary, and conversely, involuntary -movements can sometimes be brought under the subjection of the will. -From this subjection it is but a short step to the acquisition of -co-ordinations which express themselves as movements newly acquired by -the individual,” and, “The integrating power of the nervous system -has, in fact, in the higher animal more than in the lower, constructed -from a mere collection of organs and segments a functional unity, an -individual of more perfected solidarity,” also “a single momentary -shock produces in the nervous arc a facilitating influence on a -subsequent stimulus applied even 1400σ later.” I will give but one more -statement from this work which seems to tell against my humble position -of initiative in evolution. Professor Sherrington says at the end of -his book, speaking of the adjustments of nervous reactions in the -lifetime of the individual: “These adjustments though not transmitted -to the offspring yet in higher animals form the most potent internal -condition for enabling the species to maintain and increase in sum -its dominance over the environment in which it is immersed.” A little -care in reading the foregoing chapters will show that this in no way -contradicts the views expressed. - - -Facilitation. - -From Professor Starling’s Principles of Human Physiology I may again -quote part of his account of Facilitation or “Bahnung.” “When an -impulse has passed through a certain set of neurones to the exclusion -of others it will tend, other things being equal, to take the same -course on a future occasion, and each time it traverses this path the -resistance in the path will be smaller. Education is the laying down -of nerve-channels in the central nervous system, while still plastic, -by the process of ‘Bahnung’ along fit paths combined with inhibition -(by pain) in the other unfit paths. Memory itself has the process of -facilitation for its neural basis,” again, “stimulation of one anterior -root produces no definite movement of a group of muscles, but partial -contraction of a number of muscles which do not normally contract -simultaneously. Thus, stimulation of a sensory nerve may provoke either -flexion or extension of a limb, not both simultaneously. Stimulation -of the motor roots will cause simultaneous contraction of both flexor -and extensor muscles. It is _this subordination of morphological to -physiological arrangements_ in the limbs which has necessitated the -foundation of limb-plexuses.” (Italics not in the original). Professor -Graham Kerr in his work on Embryology before mentioned says: “In early -stages of Evolution, whether phylogenetic or ontogenetic, we may take -it that vital impulses flitted hither and thither in an indefinite -manner within the living substance and that one of the features of -progressive evolution has been the gradual more and more precise -definition of the pathways of particular types of impulse, as well as -the transmitting and receiving centres between which they pass. We may -then regard the appearance of neuro-fibrils within the protoplasmic -rudiment of the nerve-trunk as the coming into view of tracks, along -which, owing to their high conductivity, nerve-impulses are repeatedly -passing. It may be that as each successive passer-by causes a -jungle-pathway to become more clearly defined so each passing impulse -makes the way easier for its successors and makes it less likely for -them to stray into the surrounding substance” (p. 112). - -Professor Macdonald, in the Portsmouth address referred to, speaking of -the states of the cells under excitation, rest, and inhibition, says -“_excitation_ is associated with an increase in pressure of certain -particles within the cells; in _rest_ these particles are in their -normal quantity and have their normal number. During _inhibition_ they -are decreased in number or have a retarded motion. Thus it happens -that the excited cell tends to grow in size, on the other hand the -inhibited cell tends to diminish, and the resting cell to remain -unaltered in the nervous system. Structure is everywhere the outcome -of function.” Speaking of the relationship of parts within the nervous -system, “In so far as it is fixed, it is a sign of the orderly action -of circumstance upon the structures of the body, and the result rather -than the cause of the monotony of existence. I hold it as probable -that all the individual structures of the nervous system, and so in -the brain, have just so much difference from one another in size and -shape and in function as is the outcome of that measure of physical -experience to which each one of them has been subjected; and that the -physiological function of each one of them is of the simplest kind. -The magnificent utility of the whole system, where the individual -units have such simplicity, is due to the physically developed -peculiarities of their arrangement in relation to one another, and -to the receptive surfaces and motor-organs of the body.” As to the -lens-system of the eyeball he remarks, “Surely there is no escape from -the statement that either external agency cognisant of light, or light -itself has formed and developed to such a state of perfection this -purely optical mechanism, and that natural selection can have done no -more than _assist_ in this process.” He applies the same conclusion -to the formation of the sound-conducting and resonant portion of the -ear as well as the semi-circular canals and to the cerebellum. These -statements are not strictly associated with this chapter but bear by -analogy very strongly on the matter at issue. Indeed the whole of this -address might be utilised by a junior counsel for Lamarck if he rested -alone on the authority of a leading physiologist. The same may be said -of the anatomist whose _Arboreal Man_ has attracted so much attention. -Speaking of the arboreal habit in the phylogenetic history of mammals -he asks the question, “How did this factor enable that particular stock -to acquire supremacy?” and says that it will be answered as far as it -is possible, by the study of the influence of the arboreal habit upon -the animal body; which may be put in another way as the production of -reflex-arcs suited thereto (p. 3.) Of the muscle groups of fore and -hind limbs he says, “With a simple arrangement of anatomical parts -a slight shifting of muscular origins has turned a perfectly mobile -second segment into a supporting segment constructed upon very simple -lines: that these changes are those produced by the demands of support -from the hind-limbs in tree-climbing seems obvious” (p. 6); of the -position of uprightness upon a flexed thigh of an arboreal man, “It is -tree-climbing which makes this posture a possibility” (p. 63). “But it -is not to be doubted that the underlying principle is clear enough, -that the arboreal habit develops the specialised and opposable thumb -and big toe” (p. 71). “Even before the power of grasp is developed, -we may imagine the dawn stages of educational advances initiated by -hand-touch” (p. 159). “Tactile impressions gained through the hand are -therefore perpetually streaming into the brain of an arboreal animal -and new avenues of learning about its surroundings are being opened up -as additions to the olfactory and snout-tactile routes” (p. 160). He -asks also the pertinent question, and says at least a partial answer -to it can be given, “Did the cerebral advance create the physical -adaptations, or did the physical adaptations make possible a cerebral -advance?” (p. 196). Two more statements from this chapter show what -the answer to this question from the _anatomist_ would be--“and again -in the evolutionary story we are forced back to consider a combination -of seemingly trivial, and apparently chance associations: in this case -the dawning possibilities of neo-pallial developments combined with -the physical adaptations _due directly to environmental influences_” -(p. 198). I have ventured to underline this passage. - -I regret the necessary length of these quotations but, on account of -them, can the better be suffered to finish this study, when I briefly -consider certain well-known nervous reactions in the cat and dog as -to their probable origin. It would be a highly interesting thing to -hear an exposition by an expert of all the reflexes and reflex-arcs of -such a system as those which in a cat, dog, ape, or man are concerned -with the passage of a morsel of food from the mouth through all its -chequered and varied career till it undergoes metabolism and excretion, -but I could not do it if I would, and would not here if I could, -because of their fundamental fixed and innate character, and I think -it simpler and safer to refer to such minor reflex-arcs as those which -govern the scratch-reflex in a dog, the pinna reflexes in a cat, and a -few smaller ones, on the principle of _ex uno disce omnes_. Such minor -nerve-mechanisms as these in a pair of well-known domesticated animals -will suffice for evidence on behalf of initiative in evolution. - - -The Scratch Reflex. - -The scratch-reflex in the dog, which like the tendon-reflex in man was -in my youth a subject for schoolboy tricks, has received a vast amount -of attention and research from physiologists to whom it has brought -valuable fruit. It is a familiar phenomenon in a familiar friend of -man. There is a saddle-shaped area on the back of the dog over which -it was found empirically that even a light stimulus when applied -rhythmically, produces the “scalptor-reflex” or a reflex rhythmical -action of the flexor muscles of the leg on the same side, calculated to -remove the irritating causes of the stimulus. This includes a series -of receptors in the skin leading to a spinal segment in the region of -the shoulder, a long neurone in the cord, then a motor neurone, the -axon from which activates the flexor muscles of the leg and produces -scratching. It is described as an efferent arc from receptor to the -motor neurone, from which the Final Common Path supplies the motor -apparatus or effector. Professor Sherrington says that in this reflex -a single stimulus which is far below threshold intensity is found -on its fortieth repetition and nearly four seconds after its first -application to become effective and provoke the reflex and that its -frequency is about 4.5 per second. The reflex movement remains rhythmic -and clonic under the strongest as under weaker stimulation. When it is -easily elicitable the scratch-reflex can be evoked by various forms -of electrical as well as mechanical stimulation, but, when not easily -elicitable, electrical stimulation fails whereas rubbing or other -mechanical forms of stimuli still evoke it, though less vigorously than -usual. This reflex can also be set aside by the “nociceptive arc from -the homonymous foot” or, in other words, a nocuous stimulus to the leg -of that side produces “interferences which amounts to inhibition.” -Empirically it is easy to notice also that if the “scalptor-reflex” -can be elicited on both sides of the body, the dog when standing will -momentarily lose the power in the hind legs. - -_Note._--The rhythm of this reflex act is so special even to the -layman that lately I had a singular confirmation of its stereotyped -character, when lying awake at night and being puzzled by a curious -rhythmical scratching sound coming from my next door neighbour’s back -yard. It might have been taken by a wakeful person for some mechanical -work on the part of a burglar, but after listening repeatedly to the -apparently familiar sound I found that it came from the kennel of a fox -terrier kept by my neighbour. - - -Purposes of Reflexes. - -All reflexes being purposive this particular innate reflex is -acknowledged to have for its purpose the grooming or cleaning of the -skin over its hereditary territory. This introduces its connection -with initiative here propounded, and the justification for its -introduction is contained in Professor Sherrington’s statement that -“In the analysis of the animal’s life as a machine in action there can -be split off from its total behaviour fractional pieces which may be -treated conveniently, though artificially, apart, and among these are -the reflexes we have been attempting to decipher”--scratch-reflexes and -others. There seems to be no reason for the existence and stereotyped -character of this reflex except the need or rather the desire (if -one may use a convenient but inaccurate term) on the part of the dog -to remove an irritant which disturbs its comfort when at rest. Some -“minor horrors,” probably fleas moving across the skin-receptive -field of its shoulder and back, must be assumed to be the irritant in -question. This touches the great question of the initiative of this -remarkable reflex, which seems more fixed and powerful in the dog as -we know him than that other reflex which leads him to turn tail and -flee immediately he sees a boy stoop down as if to pick up a stone. I -dare say a clever advocate on the opposite side might impress a jury by -building up a case under which an adaptation to a protective need would -be conceived as responsible for the rapid flight at the sight of the -threatening attitude of the boy. Such a reconstruction is not required, -for it is perfectly clear that in the history of the domesticated -dog the selection of such an adapted reflex could have no place. The -survival-value of this reflex would be nil, for the number of dogs -killed by a stone or maimed for life would be so negligible that the -production of a specialised reflex for the purpose by selection or -survival of the fittest would not arise. Obviously the danger would -be intermittent and rare; and dead dogs tell no tales. On the other -hand it would be highly unpleasant for dogs to be hit by stones and -educability would lead them to avoid the stooping attitude associated -with missiles. - -We are told on high authority that not education but educability -is transmissible, and yet this humble reflex appears in very young -dogs that could hardly if ever have known the impact of a stone. -Incidentally we are compelled to remember how in past battles of our -youth the aim both of “ourselves and the enemy” was deplorably poor, -and not from want of practice. This school-boy-stone reflex is either -an example of educational effects transmitted or of a minute bit of the -unpacking of an original complexity which it would require the brain of -a de Quincey to work out. But if we suppose the initial stages of such -a stimulus as the occasional impact of a stone in many generations to -be slowly ingrained in the skin-receptors, reflex-arcs and receptors we -do not need opium either for the acceptance of orthodox dogma or to aid -us in the Mendelian alternative to a very simple ideal construction. - -This digression bears on the initiative of the more important -scratch-reflex, and it is profitable to ask “are not both of these -reflexes in dogs examples of Evolution of the Indifferent?” Is it -possible to imagine that from its inception to its fully-formed state, -with a specialised territory of skin-receptors accurately mapped -out, with receptor neurones, reflex-arcs and adapted effectors, this -scratch-reflex can have arisen through Germinal Selection or selective -processes within the germ? At no stage can anything more than a -contribution to more or less comfort to the animal be held to result -from its operation. It is strangely reminiscent of the proceedings -of an elderly man after lunch on a hot day when he protects his head -against house-flies with a handkerchief. I am aware that it is but one -of a large number of reflexes produced for the purpose of grooming -the trunk head or limbs of animals as low down in the scale as the -house-fly or grasshopper, many of which were beautifully described -a few years ago by Miss Frances Pitt in the _National Review_ in an -article dealing with small mammals, chiefly rodents. But I have availed -myself here as elsewhere, of the liberty of doing what Professor -Sherrington says we may do, and consider this scratch-reflex as -split off from the rest of the animal’s behaviour for the purpose of -analysis. He also says in discussing the subject of parasites moving -across the receptive surface of the skin that the ulterior purpose -may be the removal of what “would confuse its function as a receptive -surface to more significant environmental stimuli.” This statement is -hypothetical and the problem obscure; but at any rate we know this that -the removal of the parasite must conduce to the greater comfort of the -dog without any more recondite purpose. The one suggested by Professor -Sherrington would in some possible but very vague manner be referable -to selection, but, whether the suggestion be valid or not, it is almost -impossible to suppose that a saddle-shaped area of the kind described -could be under the guidance of selection. The law of Parcimony forbids. -There is a close similarity between this saddle-shaped area in the dog -and that on the cow’s trunk described in Chapter X. It is difficult -to believe that from man downwards to grasshoppers relief from mild -irritating causes such as this is not enjoyable to the particular -animal, and yet indifferent altogether as to its survival in the -struggles of life for food and mates. The “scalptor-reflex” only -reaches the limits of the receptive field of the scratch-reflex and it -is contrary to observed facts that parasites confine their depredations -just to the region where the formidable scalptor-reflex can reach. The -wicked flea knows better than that. The initiative of this reflex can -well be pictured as taking place in domesticated dogs and their wild -ancestors whose habitats in prehistoric times were probably infested -with these irritants to such a degree that no modern mind can conceive, -and the adequate stimuli, leading to receptors after ages of impact and -consequent hammering out pathways through certain reflex-arcs until -the required weapons of offence or effectors were organised into a -_defensive-offensive system_--were there in profusion. But a great and -fundamental principle of the evolutionary process such as Selection -is not honoured by being dragged in, even for forensic purposes, -to account for results which owe to the search for comfort their -perfection of organisation. I have personally seen in some professional -invalids of the softer sex nearly as perfect adaptations to their -comfort which in no way contributed to their length of life. This may -be put aside as irrelevant but it is at least suggestive. - -I submit the statement as to the scratch-reflex in the dog that from -beginning to end it is an _indifferent_ mechanism and the probability -is immense that its initial stages were governed alone by repeated -stimuli from parasites which produced receptors, conducting fibres -afferent neurones and efferent neurones, leading into the Final -Common Path controlling the flexors of the hind limb. It would then -come under the Law of Subjective or Hedonic Selection formulated by -Professor Stout in the words: “Lines of action, if and so far as they -are unsuccessful, tend to be discontinued or varied; and those which -prove successful to be maintained. There is a constant tending to -persist in those movements and motor attitudes which yield satisfactory -experiences, and to renew them when similar conditions recur; on the -other hand those movements and attitudes which yield unsatisfactory -experiences tend to be discontinued at the time of their occurrence, -and to be suppressed on subsequent similar occasions.” - -In this connection a statement from Professor McDougall’s work may be -advantageously quoted. He says that “It is characteristic of those -(arcs) of the higher or third level that their organisation, their -interconnections, by means of which the simpler neural systems of -great complexity, is _congenitally determined in a very partial degree -only_, and is principally determined in each individual by the course -of its experience. The arcs of the higher level thus constitute the -physiological basis or condition of docility, the power of learning by -experience.”[88] (My italics) - - [88] _Op. cit._ p. 21. - - -Scratch Reflex of the Cat. - -There is a notable difference between the scratch-reflex of the dog -and that of the cat, especially as to the site of its receptive-field. -That of the dog has been referred to, but it appears to be generally -accepted that the cat has no such saddle-shaped or indeed other area of -skin receptive-field on its back or flanks. I have repeatedly tried by -various mechanical stimuli, applied both irregularly and rhythmically, -to evoke a scratch-reflex in a cat, young or adult, on the surface -corresponding to that of the dog, and have found no response. This -has been tried both when the animal was awake and when asleep. But -the receptive field of the cat’s scratch-reflex has received careful -and elaborate attention, which is described in a paper by Professor -Sherrington in the _Journal of Physiology_, Vol. LI. No. 6. By means of -delicate stimuli, mechanical and electrical in a decerebrate cat, the -receptive-field of the scratch-reflex has been accurately delineated -in the pinna, and several other pure reflexes have been obtained. -These are protective of the pinna; some, the retraction and folding -reflexes seem directed against irritant touches, _e.g._ the settling -of fleas--or against exposure to injury in fighting; others, the cover -and head-shake and scratch-reflexes against the ingress of foreign -matter, such as dust, water, insects, into the meatus and ampulla. The -threshold for their elicitation is extremely low, that is to say, they -require very gentle stimuli to evoke them, while with the exception of -the scratch-reflex they are elicited with difficulty and uncertainty -_by electrical stimuli_ (My italics) to which the animal has been -subjected in the course of its total experience. He adds that the -pinnal reflexes are readily obtained in the normal animal, and I may -allude here to some small observations I made on a normal young cat -during profound sleep, recorded in _Nature_, Vol. 106, Sept. 2, 1920. -Light mechanical stimuli, applied during this state of deep sleep to -the internal surface of the pinna, especially close to the meatus, -produced first, twitching of the facial muscles on the same side; -second, as this ceased the fore foot was moved irregularly towards the -ear, and third, as this ceased a rhythmical scratching action of the -hind foot took its place, the rate of which seemed to be exactly the -same as that of the scratch-reflex in the dog evoked from stimulation -of the flank and back. I had not then, unfortunately read more than -an abstract of the above paper, but if the full account be followed -it will be seen that the various “territories” belonging to all the -former-reflexes are now known as well as the frontiers of a European -Kingdom. All I was able to do with this unusual opportunity of a heavy -sleep in a normal young cat was to verify more roughly Professor -Sherrington’s observations and slightly to extend them _in respect of a -sleeping animal_. - -In the course of these observations on a young cat I examined the -various regions of the back and flanks with mechanical stimuli of -different degrees of strength. These were applied during sleep and I -found that it was more often during a moderate than a light or deep -sleep that the following results were shown--chiefly under the stronger -stimuli the tail was raised sharply and swept in a circular way, and -this would be repeated according as the stimulus was applied; but at -the same time there was shown a strong, irregular twitching along the -flank, extending forwards to a point near the level of the shoulder. -This latter reflex would appear to be a reaction on the part of the -panniculus carnosus. Both the reflex of the muscles of the tail -and this of the flanks appear to be connected in their origin with -movements of parasites in their respective territories. - -In considering the scratch-reflex in the cat a subtle bit of adjustment -is found. That coarse and simple scratching of its ear, which we see -so often in the cat, must have often astonished us for its vigour and -yet its bloodless character. This action is of course a purposeful -one, for it goes on when the animal is awake. Here if anywhere this -profoundly hedonistic animal shows that for it the laws of comfort -are its laws of conduct. It is clear that there may be two processes -or conditions involved in its bloodless violence. On the one hand the -reflex retractile mechanism of the claws may be kept in abeyance by -another reaction which is pre-potent; on the other, it is a fact that -the hind foot in the cat is furnished with claws which are much blunter -than those of the fore foot. As far as I have been able to examine cats -of different ages I have found the claws of the hind foot more like -the blunt claws of a dog than the familiar sharp claws of the Felidæ. -So in the violent scratching referred to there may be a double reason -associated in the process. As to the difference in the sharpness of the -fore and hind claws it would appear to be remarkably like a transmitted -bit of adaptation initiated and kept in being by use and habit in -progression, for the hind foot in such animals as the cat has a larger -share in this action than the fore foot. But here it is difficult as so -often to assign to selection its possible share of the adjustment. - -Certain minor but persistent reflexes may be briefly mentioned in -support of this side of the evolutionary process. In the dog and cat, -as we know them, the action of the muscles of the tail by which it is -elevated during the act of defæcation is very suggestive of a reflex -acquired by a very small degree of physical comfort and repeated in -countless individuals, wild and domesticated. I have seen not only this -but a few small scratches made by a cat before defæcation in a kitten -as young as three weeks old. It is also mentioned in illustration of a -vestigial character that a horse will paw the ground with no immediate -apparent object, the act being derived from ancestors which thus -cleared away snow from the ground. This is claimed, doubtfully I think, -as a vestige of a formerly _useful_ habit but seems more probably to -be one of these indifferent reflexes connected with comfort than with -survival-value. - -It will be observed that in this branch of the case for Lamarck _v._ -Weismann the indirect evidence from inference far exceeds in amount -that of direct experimental evidence, but from the nature of the -problem under consideration this could not be otherwise. - -If we may again look back in thought over the long series of animals, -from man downwards, we shall picture those of the spinal level -striving (with apologies for the use of an anthropomorphic word) to -reach the sensory level and finding out the fact that few there be -that enter therein. Again we see in vision the higher creatures of -the sensory level reaching forwards to the strait paths of primate -existence, and again finding the difficulty of self-advancement that -their predecessors found. We see the elect few of these, by a happy -combination of nature and nurture, uprearing to glory and honour the -primate stock with its culmination in man. A long vista indeed and a -vision, but assuredly no mere figment of the imagination, as some of -the slender facts and arguments here would seem to show. With Professor -Bateson we personify Nature in the story, with her wonted coyness -betraying the fact that though she is stern she has her tolerant -moods; that she allows her children, even that “insurgent son” who -calls himself Homo Sapiens, a genial liberty to frame new reflex-arcs -which make for his enjoyment of life in indifferent fields, and _that -the great neural process of Facilitation is the leading factor in -their constructions and probably also in more deeply-based systems of -sensori-motor arcs_. - - - - -SUMMARY. - - -Though it be true that _dolus latet in generalibus_, it is a more -important truth that “without premature generalisations the true -generalisation would never be arrived at.”[89] - - [89] Herbert Spencer, _Essays_, II, 57. - -Therefore I conclude:-- - - 1. That Plasto-diēthēsis, or the moulding and sifting processes - experienced by organisms, represents the beginning and end of higher - animal evolution; and that its wide hyphen stands for the provinces - where Mendelism, Mutationism, Tetraplasty, Orthogenesis, and the - dynamical work of growth on Form, as well as other factors yet to be - discovered, can range at large. - - 2. That personal selection is the leading form of that process in - higher animals, whereas among Invertebrates, especially unicellular - forms, selection of groups is the rule. - - 3. That Initiative in animal evolution comes by stimulation, - excitation, and response in new conditions, and is followed by - repetition of these phenomena until they result in structural - modifications, transmitted and directed by selection and the laws - of genetics--a series of events which agree with Neo-Lamarckian - principles. - - 4. That undesigned experiments in the arrangement of the Mammalian - hair, and the production of new bursæ, as well as the designed - experiments of Pawlow, support the foregoing claims, with which agree - the converging facts of--varieties of epidermis, arrangement of the - papillary ridges, flexures of the palm and sole, the formation of the - plantar arch, the origin of certain muscles, the innervation of the - human skin, and the building of reflex-arcs. - - 5. That there is a large place in higher animals for the Evolution of - the Indifferent through the action of use and habit. - - 6. That the position for Initiative in Evolution here advanced is no - bar to unlimited research. - - - - -INDEX. - - - Adami, Professor. “Medical Contributions to the Study of Evolution,” - 21. - - Ancestry, primate, 235, 236. - - Anthropology, 4. - - Ape: Arrangement of hair on forearm of, 43. - - ----Papillary ridges on hand and foot of, 164. - - ----Bursæ of, 184–186. - - ----Muscles of, 213, 214. - - Artists, Evidence from, 66. - - Ass: Hair-patterns of, 82. - - - Baboon, Chacma, papillary ridges on hand and foot of, 165, 166. - - Bartholinus, Erasmus, 126. - - Bateson, Professor, 9, 20, 22, 33, 149, 255. - - ----“Materials for the Study of Variation,” 9–13, 22, 210. - - Bayliss, Professor, 244. - - Bear, Parti-coloured (_Æluropus melanoleucus_): Hair-patterns of, - 121, 122. - - Beddard, Mr., 118. - - ----“Animal Colouration,” 206. - - Bell, Sir Charles, 205. - - Bergson, 205. - - Bongo (_Tragelaphus euryceros_): Hair-patterns of, 118. - - Bonney, Professor. “The Story of Our Planet,” 3. - - Bower, Professor, 21. - - Brooks, Professor, W. K., 20, 202. - - Bursæ, description of, 179, 180. - - ----Human, enumerated, 180–183. - - ----Experiments as to, 186–190. - - - Canidæ: Hair-patterns of, 98–102. - - Capybara, epidermis of, 151. - - Chimpanzee, papillary ridges on hand and foot of, 164, 167, 168, 176. - - ----Bursæ of, 184, 185. - - Clark, Sir Andrew, 30. - - Cold and warmth sensations of human skin, 220–230. - - Coote, Captain, 194. - - Correlation, 28. - - Correns, 11. - - Cow, hair and habits of, 87–91. - - ----Fly-shaker muscles of, 90, 211, 212. - - Crime, detection of a, 5. - - Cunningham, J. T., 21. - - - Darwin, 1, 2, 15, 35, 39, 40, 139, 145, 147, 239. - - ----“Origin of Species,” 2, 8. - - ----“Descent of Man,” 2. - - ----Three Blows to, 9. - - ----On human eyebrows, 64, 65. - - Darwin, Sir Francis, 20, 21. - - ----On Mnemonic theory of Heredity, 20. - - Darwinism, 9, 15, 25, 145. - - Dendy, Professor. “Outlines of Evolutionary Biology,” 21. - - de Vries, 11, 24, 27, 145, 190. - - Dog: Arrangement of hair of, 27, 28, 34, 100–102. - - ----Habits of, 98, 99. - - Dyer, Professor Thiselton, 210. - - - Earth Wolf, epidermis of, 150. - - Echidna, epidermis of, 151. - - Elliott, Professor Scott, 98, 126. - - ----“Prehistoric Man and his Story,” 43, 47, 226. - - Environments, Discontinuous, 31–33. - - Epidermis: Varieties of, found in mammals, 145. - - ----Stimuli and response, 145–153. - - Eyebrows, hairs of human, 64–73. - - ----Interpreted by wrinkles, 67. - - - Facilitation, 240, 246–248. - - Felidæ: Hair-patterns of, 92–97. - - ----Snout of, 94. - - Flexures of hand and foot, description of, 170–172. - - ----Chief types of, 172. - - ----Meaning of, 173–177. - - Foot of Man, 155, 156. - - ----Papillary ridges on, 159, 160. - - ----Flexures of, 176, 177. - - Foot of Man, Plantar arch of, 192–194. - - ----Muscles of, 214–217. - - Forearm, arrangement of hair on, 41. - - - Galton, 157; On chiromantic creases, 170. - - Galvani, 126. - - Geikie, Sir Archibald, 3. - - Genealogy, 4. - - Germinal Selection, 19, 20. - - Gibbon, flexures of foot of, 176. - - ----Bursæ of, 185. - - Gibbon, Hainan, papillary ridges on hand and foot of, 164, 165. - - Giraffe: Habits of, 115. - - ----Hair-patterns of, 117. - - Gorilla, papillary ridges on hand and foot of, 164. - - - Haeckel: Pithecoid Ancestors of Man, 1. - - Hair-direction, causation of, 140–144. - - ----Summary of conclusions with regard to, 141. - - ----Phenomena of, 37, 38. - - ----Experimental Inquiry into, 125, 126. - - ----Steps of Inquiry into, 40, 124, 125. - - Hair-pattern, Dynamics of, 44, 45, 46, 50. - - Hand of Man, 155, 156. - - ----Papillary ridges on, 157–159. - - ----Flexures of, 176, 177. - - ----Muscles of, 214–217. - - Harris, Dr. H. Wilder, 147, 154. - - Harris, Mrs. Wilder. _See_ Whipple, Miss Inez. - - Hartmann, 213. - - Hedgehog, epidermis of, 152. - - ----Papillary ridges on hand and foot of, 162, 163, 166. - - ----Flexures on hand and foot of, 173. - - Hepburn, Dr., 148, 159, 162. - - Heredity, Mnemonic theory of, 20. - - Herschel, Sir John, 126. - - Hill, Professor Leonard, 224. - - Historian a biologist, 2. - - Horse: Arrangement of hair on side of neck of, 51–63. - - ----Habits of, 75. - - ----Hair-patterns of, 75–82. - - ----Compared with Zebra, 83–85. - - ----Effect of harness upon hair of, 126–136. - - ----Fly-shaker muscles of, 211. - - Howes, G. B., 12. - - Hutchinson, Professor Jonathan, 188. - - Hutton, 3. - - Huxley, 5, 8, 126, 192, 200, 217. - - - Insectivores, 237, 238. - - - Jackson, Hughlings, 241. - - Jevons, 124, 125, 126, 140. - - Johnston, Sir H. H., 96, 201. - - Jones, Professor Wood, 230. - - ----“Arboreal Man,” 195, 245, 248. - - - Kammerer, 21. - - Keith, Professor, 112, 188, 189, 190, 195, 196, 208, 215, 216, 217. - - ----On functions of platysma, 113. - - Kerr, Professor Graham, 224. - - ----On Embryology, 246, 247. - - Kiang (Thibetan Wild Ass): Hair-patterns of, 119. - - Kinkajou, epidermis of, 153. - - Kropotkin, Prince, 21. - - - Lamarck, 13, 21, 22, 33, 35, 145, 147, 247, 255. - - Lamarckian hypothesis of organic evolution, 19, 20, 22, 24, 25, 26, - 28, 30, 31, 138, 205. - - Lankester, Sir E. Ray, 20, 23, 45, 141, 190, 204. - - Lemur: Arrangement of hair on forearm of, 43. - - ----Hair-pattern of, 46. - - ----Papillary ridges on foot of, 161, 162, 164, 165. - - ----Black-headed, epidermis of, 153. - - ----Ring-tailed, epidermis of, 153. - - ----Flexures of foot of, 176. - - Lion: Hair-patterns of, 92–97, 207. - - Livingstone, 92. - - Llama: Hair-patterns of, 119, 120. - - Loris, Slow: epidermis of, 154, 155. - - ----Papillary ridges on foot of, 161, 166. - - Lydekker, 86, 92, 94, 115, 118, 119, 168, 195. - - Lyell, 3, 178, 192. - - ----“Principles of Geology,” 3, 46. - - - Macacus, flexures of hand and foot of, 176. - - Macalister, 215, 217. - - McBride, Professor, 21. - - Macdonald, Professor, 190, 244, 245, 247. - - McDougall, Professor: On Physiological Psychology, 24, 25, 225, 253. - - MacEwen, Sir W., 188. - - McTaggart, Dr., 142. - - Malthus, 2, 15. - - Malus, 126. - - Mammals, palms and soles of, 150–153. - - Man: hair and habits of, 103. - - ----Arrangement of hair on back of, 104. - - ----Passive habits of, 106, 107. - - ----Arrangement of hair on chest of, 108, 109. - - ----Palm and sole of, 155, 156. - - ----Papillary ridges on hand of, 157–159. - - ----Papillary ridges on foot of, 159, 160. - - ----Flexures of palm and sole of, 176, 177. - - ----Plantar arch of, 192–194. - - ----Muscles of hand and foot of, 214–217. - - ----Changes in habits of, 234, 235. - - Marmoset, Papillary ridges on foot of, 161. - - Mendel, 11, 15, 26, 145, 190. - - Mercier, Dr.: On Causation, 141, 142. - - Mill, John Stuart, 141, 142. - - Mole, epidermis of, 150. - - Monkey, papillary ridges on hand and foot of, 164. - - Mule: Hair-patterns of, 82. - - Murphy, Dr. John B., 189. - - Muscles: Anatomists’ views of, 201, 202. - - ----Initiative in, 202, 203. - - ----New, 205. - - ----Unstriped, 205, 206. - - ----Facial, of expression, 207–209. - - ----Fly-shaker, 210–212. - - ----Skeletal, 212, 213. - - ----Skeletal, of Primates, 213, 214. - - - Neural phenomena, 239. - - Nervous System: Some aspects of the, 223–225. - - ----Place of the, in Evolution, 238, 239. - - ----Raw materials of the, 240, 241. - - ----Integration of raw materials of the, 241, 242. - - - Oken, 126. - - Ollier, 188. - - Onager, Hair-patterns of, 82. - - Opossum, American, epidermis of, 151. - - ----Azara’s, epidermis of, 153. - - Orang, papillary ridges on hand and foot of, 164. - - ----Bursæ of, 185. - - Organic Evolution, consideration of problems of, 24–28. - - ----Factors in, 27. - - ----Cross-roads in, 203–205. - - Owen, Richard, 10. - - Oxen: Hair-patterns of, 87–91. - - - Palm, skin of, 147–156. - - ----of Man, 155–156. - - Papillary ridges, some undersigned experiments in, 166–169. - - Paterson, Dr. C., 188. - - Pearson, Professor Karl, 34, 141, 142. - - Phalanger, epidermis of, 152. - - Pitt, Miss Frances, 94, 95, 251. - - Plantar arch, of man, 192–194. - - ----How it was built, 194, 195. - - ----Equipment of, 196, 197. - - ----Description of, 197–199. - - Plasto-diēthēsis, 34, 145, 195. - - Platysma, Struggles of the, 111–114. - - Playfair, 3. - - Pocock, Roger, 75. - - Poincaré, Henri, 157. - - ----Principles of method, 36. - - Porcupine, Canadian Tree, epidermis of, 151, 153. - - Poulton, Professor: “Essays on Evolution,” 86. - - Prescott’s “Conquest of Peru,” 120. - - Pressure, Examples of the effects of, upon hair-direction, 127–136. - - Primates, epidermis of, 153. - - - Rabbit, epidermis of, 151. - - Records, Interpretation of, 110. - - Reflex arches, formation of, 231. - - ----Some historical illustrations of, 231–234. - - ----Of Insects, 236, 237. - - ----Of Mollusca, 236, 237. - - ----Of Birds, 236, 237. - - ----Evidence of production of new, 242–246. - - Reflexes: Stimuli of, 249–256. - - ----Scratch, of the dog, 249. - - ----Purposes of, 250–253. - - ----Scratch, of the cat, 253. - - Rivers, Sources of, 4. - - Romanes: 19, 39, 40, 145. - - ----On Weismann, 17, 18. - - Roux, 19, 145. - - Russell, The Hon. Bertrand, 142. - - Russell, E. S. On Lamarck’s theory, 20. - - - Saint-Hilaire, Geoffrey, 10. - - Sapajou, Brown, papillary ridges on hand and foot of, 165. - - Schafer’s “Text Book of Physiology,” 219, 220, 226. - - Scratch reflex; of the dog, 249. - - ----Of the cat, 253. - - Selous, 92, 115, 118. - - Sherrington, Professor, 218, 226, 229, 238, 244, 245, 249, 250, 251, - 253, 254. - - Skin, Human: Distribution of Touch Corpuscles, 219. - - ----Distribution of Touch Spots, 219. - - ----Distribution of Cold and Warmth Sensations, 220. - - ----Distribution of Cold and Warmth Spots, 220, 221. - - ----Stimuli of pressure, 222, 226–230. - - ----Stimuli of cold, 226–230. - - ----Stimuli of pain, 226–230. - - ----Stimuli of warmth, 226–230. - - Sloth, Two-toed (_Cholæpus didactylus_): Hair-patterns of, 122, 123. - - Smith, Dr. E. Barclay, 201, 216. - - Sole, skin of, 147–156. - - ----Of Man, 155, 156. - - Spencer, Herbert, 28, 177. - - Squirrel, epidermis of, 152. - - ----Papillary ridges on hand and foot of, 162, 166. - - ----Flexures of hand and foot of, 175. - - Squirrel-monkey, papillary ridges on foot of, 161. - - ----Flexures of foot of, 176. - - Starling, Professor, 227, 244. - - ----On Facilitation, 240, 246. - - Still-born children, subcutaneous bursæ of two, 183, 184. - - Stimuli, 30, 31. - - ----Of touch, 219, 226–230. - - ----Of cold, 220, 226–230. - - ----Of warmth, 220, 226–230. - - ----Of pressure, 222, 226–230. - - Stout, Professor, 252. - - Summary of conclusions arrived at, 257, 258. - - - Thomson, Professor J. Arthur, 20, 22, 23, 24, 25, 28, 29, 34. - - ----On Heredity, 22. - - Touch Corpuscles, 219, 227, 228. - - Touch spots, 219, 225, 227, 228. - - Tschermak, 11. - - - Ungulates, even-toed, 86–91. - - ----odd-toed, 74–85. - - - Vernon, Dr.: “Variations in Animals and Plants,” 28. - - Vulpine phalanger, flexures of foot of, 173, 175. - - - Wallace, Professor, 2, 39, 40, 46, 145. - - Weber’s Law, 222. - - Weismann, 9, 11, 14, 16, 17, 18, 21, 22, 24, 25, 26, 86, 139, 177, - 210, 245, 255. - - ----Twelve points, 15, 16. - - Weismannism, 17, 18, 19, 26, 145. - - Welton, Mr., 142. - - Whipple, Miss Inez (Mrs. Wilder Harris), 154, 162. - - ----Criticism of “The Direction of Hair in Animals and Man,” 137–139. - - Wolff, 189: “Law of Bone Transformation,” 205. - - - Young, Arthur, 143. - - - Zebra: Comparisons between horse and, 83, 84. - - - - - -End of the Project Gutenberg EBook of Initiative in Evolution, by Walter Kidd - -*** END OF THIS PROJECT GUTENBERG EBOOK INITIATIVE IN EVOLUTION *** - -***** This file should be named 53319-0.txt or 53319-0.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/3/3/1/53319/ - -Produced by Thiers Halliwell, Chris Curnow and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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