Initiative in Evolution

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.

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.

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.

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.

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.

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.

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.

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:—

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.

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.

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.

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.)

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.

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.

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.

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

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.