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._