Chapter 7

PALM OF THE FOOT OF YOUNG GORILLA. BACK OF THE HAND OF YOUNG GORILLA.(From theTransactions of the Zoological Society of London.)

The Gorilla has a large head, and on looking at a stuffed specimen one is at once struck with the width and length of the face, and the great prominent brows immediately over the eyes. There appears to be no forehead, for the head recedes rapidly backwards, and then comes a high ridge of hair, in old males, running from before backwards on the top of the scalp, and meetinganother which is less prominent, and placed across the back of the skull, from the back of one ear to that of the other. The animal has the power of moving the flesh and skin which constitute the scalp freely forwards and backwards, so that when it is in a rage its scowl is made all the more threatening and ugly by its frowning and bringing down the hairy ridge close to above the eyes. The hazel eyes are large, and they are separated by a small prominent bridge belonging to the nose, the rest of which is broad and flattened out. The jaws project forwards, and are long and wide, the teeth being large and strong, and visible when uncovered by the fleshy and rather hairy lips. The ears are small for the size of the head, when they are compared with those of other Apes, and they as well as the skin of the face are naked and dark.

Nature has been kinder to the females so far as beauty is concerned, for they have less marked crests of hair, smaller brows, and shorter side teeth, and therefore more amiable faces under all circumstances.

Of course the outside appearance of the head has much to do with the skull beneath, and this has been very carefully studied by anatomists. As a whole, the skull of a full-grown male Gorilla is larger than that of a man, but it is lighter, although it appears to be more massive on account of its being marked by great bony ridges or crests, which correspond with the lines of hair on the top and back of the head, one being on the top like the crest of a helmet, and the other crossing the back and reaching the other so as to form a rudeTshape. Careful measurement proves the great size of the Gorilla’s skull as a whole, and that this is dependent mainly on the dimensions of the bones of the face, the cavity for the brain being smaller than that of man. But it does not appear at first very easy to explain how it is that this massive-looking skull should be lighter than that of man. A careful examination of the bones of the Gorilla’s skull explains the difficulty, and in a very interesting manner.

SIDE VIEW OF THE SKULLOF GORILLA.

The massive and solid look is given to it by the crests or ridges beneath the hair already mentioned; they are of great use, for they give attachment to very powerful muscles, especially to those which move the lower jaw, and enable the teeth to bite forcibly. The surface of the bones of the head for a certain depth is solid enough, but below this solid layer there is a cellular arrangement consisting of a network of bone, with cavities communicating with each other with the internal parts of the ears and nose. Below this is solid bone again. So that there are three layers, and the central one gives lightness and strength to the whole; moreover, it protects the brain under the skull from receiving shocks during falls or blows by boughs.

When the skull receives a sharp blow, for instance, in front or behind, or low down at the sides, the outer layer of solid bone is often cracked, and even forced in. If there were no cellular layer, the tender brain would be injured directly, but the network of bone and the large spaces amongst it take off the jar from that important organ, and suffer the outer layer to be pressed in without affecting the deeper structures. It must be a very hard blow that can press the cellular layer in sufficiently to break through the third layer, which is solid but thin. Very possibly the larger air spaces of the cellular layer assist the senses of hearing and of smelling also.

There is another very strong bone connected with the skull, which feels like a ridge, passing backward from the eye to the ear; and it has something to do with the other ridges, for the muscles which are attached to them, and which pass down to the lower jaw to give it great power of mastication, are covered on the cheek by it. This cheek-bone forms a kind of arch, and gives the great breadth to the upper part of the face of the animal.

In a front view of the skull of the male Gorilla the ridge or crest on the top of the head stands up like a little peak; then over the eyes is the great brow ridge, which seems to press the upper part of the cavity for the eye (the orbit) flat, so that it is not round as in most animals, but rather square in outline. These three sets of ridges, those of the upper and back part of the brain case, that of thebrow and those of the cheeks, so large and important, are distinctive of the adult male animal, and a skull possessing them belongs to the Gorilla and to no other animal.

The females and the young of both sexes have not the top ridges, and the others are small in comparison with those of the male adults.

Clearly the ridges give strength to the head, muscular power to the jaws, and what is of great importance to a large active animal, do not interfere with the lightness of the strong skull.

The skull is hollow beneath the top and back ridges, and this space is occupied by the brain and its investing membranes, and the nerves coming from it, to supply the muscles of the face and head, the skin over them, and the organs of special sense, such as the eye, the ear, and the nose. The space is considerable, and for an Ape the Gorilla has a large brain. He has a large body, very many muscles capable of complicated movement, and he can see, hear, and smell admirably; and as the nerves which supply the necessary energy for all this come from the great nervous centre, as the brain is called, it must be of considerable size and complexity. Moreover, as many of the motions and sensations of the Ape resemble those of man, the brains of both will resemble each other to a certain extent. But all that part of the brain which serves in a manner, as yet past our comprehension, to assist the production of the high intelligence and moral powers of man, we should expect not to find in the purely sensual animal, and the expectation is realised. Again, although bone for bone, muscle for muscle, and blood-vessel for blood-vessel, those of the great Ape and man may be compared with wonderful exactitude; still man in relation to the Gorilla has a greater power of elegance of movement, and of producing complicated muscular efforts, and of employing many different muscles to produce a common end, and therefore his nervous system must be all the more perfect. Thus, the Ape cannot imitate the graceful actions which sway the body as when a well-made man walks leisurely, and it cannot get all the muscles of the mouth, tongue, and larynx (or organ of voice) to act simultaneously and orderly, so as to produce the sound of articulate voice. Yet these actions are performed by man without any special effort; they may be done without thinking, and are mechanical, as it were, or more properly, “automatic,” done as if by a machine; they require a very perfect arrangement of the nervous system, and an unusual amount of nervous matter.

No amount of schooling, could it be given, would ever make a Gorilla entertain the notion of insuring its life; arithmetic is impossible; the fine arts and poetry are unattainable, and therefore by so much is its brain the smaller and simpler.

The brain case, or the space enclosed by the crested skull bones, is compactly filled with the nervous material in all animals, so it is only necessary to ascertain the relative dimensions of the spaces in different animals to get a notion of the difference in the sizes of their brains. The space can be measured by filling it with sand, and then measuring its bulk in a proper measure.

Some Gorillas have larger spaces for the brain than others, and in this they resemble man, for there is a considerable difference between the capacity or the size of the space in a well-educated European and a savage Australian. And, doubtless, some Gorillas are cleverer than others, or are more active, generally speaking, so have larger brains; but an average may be taken of the different sizes in them as in man, and the results come out as follows:—

The average or mean size or capacity of the brain case in the Gorilla is about 31 cubic inches, a cubic inch being a six-sided space of one inch long, broad, and high. In man, the European may have a brain case holding 114 cubic inches, and the Australian only 63 cubic inches; the mean of the European size is 93 cubic inches, that of the Australian being 75. Hence the brain case, and therefore the mass of the substance of the brain of the Gorilla, is not one-half that of the lowest race of man.

Only the brains of young Gorillas have been examined, and these have not been in a very satisfactory state; but enough has been gleaned from their study to determine that they are not so high, wide, or long, relatively, as those of mankind. The brain of man is a wonderfully complex structure, and the nervous matter is folded and packed in many ways or “convolutions,” and the nerves arise from special parts which are connected by cross and long fibres or “commissures.” All these structures exist, but not in perfection, in the Gorilla’s brain; and although the nerves are large, that portion of the brain which originates their energy and action is much smaller than in man.

Apparently the brain grows to a certain age in the Gorilla, and then the skull increases in outward size, and the creature has a huge body, with mental capacities far below those of a child or man.

The ridges and crests on the top and back of the Gorilla’s skull are larger than those of any of the great flesh-eating animals of the cat tribe, and it has therefore been thought that they were a proof of the occasional bad habits of the great Ape, and of his indulging now and then in negro flesh. Large as are the crests in the old males, they are barely present in the females and young, and they must be regarded partly as of use to the larger animals, and partly as ornamental; for in animal nature, as a rule, the gentlemen are more beautiful than the ladies, the idea of beauty being, of course, very much a matter of taste. They are evidently protections against falls, and they also give origin to muscles. The back crest, when looked at from behind, is almost fan-shaped, the bone being broad, and the great muscles of the neck and back are attached to it. They pull the head backwards, and the single, long crest on the top gives origin to the muscles, which pass downwards on the temples to the lower jaw. Indeed, the energy of the muscles of the side of the head is principally devoted to the lower jaw, to its crushing, crunching, and masticating offices, for the food, although often soft enough, is occasionally inside the sugar-cane, and several harder woods. The powerful upper jaw is, of course, attached to an equally strong lower one, which forms the front and lower part of the face. The upper jaw reaches out far in front of the eyes and nostrils, and is straight rather than bulged, and appears narrow, from side to side, in comparison with the great, wide cheek-bones, but it looks formidable with four strong front teeth, projecting only slightly, and a large, long, eye tooth on each side, sticking out rather far below the others.

On looking at the under surface of the roof of the mouth and palate, the cause of the length of the front of the face is seen. Instead of the back teeth forming an open curve around the roof of the mouth, as in men, they are placed in a long, and almost parallel straight row. Five great teeth on each side thus form with the bone, into which their fangs are planted, a long side to the face. In front of these is the large eye, or dog tooth (canine tooth), mentioned above.

The palate and roof of the mouth are long and comparatively narrow, and hence no Gorilla could speak distinctly, or use his tongue glibly enough to talk as a child. Howling and a kind of bark may, on the contrary, be done to perfection.

But although of no use as regards speech, the long roof of the mouth, with its wide ranges of teeth, is of great importance to a vegetable-eating creature, which does not want the sugary juices of its food to run out of the corners of its mouth, and which spends the greater part of its time in filling its capacious stomach.[4]The lower jaw fits the upper one, and when its teeth clench with those above, the cavity of the mouth is nearly shut, and it is quite closed by the lips and cheeks outside.

As might be expected from the great muscles which unite the lower jaw to the skull, it is large and strong, but it has no projecting chin, and this slopes in a retiring manner. The side of the jaw which supports the teeth is, as in man, curved upwards behind at what is called the angle. The jaw is very movable, and can act sideways in munching, or up and down, as in biting; and having these powers—thanks to the action of different sets of muscles—it has teeth fashioned to bite, and to crunch, and to chew. They greatly resemble those of the upper jaw, on which they work, and a superficial view of them all leads to the opinion that they greatly resemble those of man; there are, however, many differences. As in the upper jaw, the front and eye teeth are nearly straight in front, the last-mentioned projecting outwards, and the front teeth biting inside the upper ones; and the back teeth are in straight rows also.

The following story is told by Du Chaillu to illustrate the cause of the wearing of the front teeth of the Gorillas. He had gone into the interior, and was suffering from hunger, so went out into the forest for game. Not finding any, he was about to retrace his steps, when he heard the unmistakable roar of a Gorilla. He writes,“I plunged forward into the thick of the forest, breaking, as I went along, small boughs to enable me to find my way back, and tearing my clothes in the thorny underwood. The roar became nearer, and seemed to shake the ground under me. I heard the rustling of the branches, and fancied there must be more than one. The excitement of the moment was great, and was increased by the prospect of obtaining food for all our party. Suddenly the roaring ceased. I stopped, thinking that it was a male, which was preparing to advance on me. But I listened in vain—the beast had fled. When I reached the spot I saw nothing but broken branches of trees. I measured some of them with my thumb, and found boughs of five inches’ diameter broken in two by the powerful grip of this monster of the forest. Although disappointed in my chase, I was glad to find a corroboration of the explanation I had given of the wearing down of the animal’s front teeth, for some of the branches plainly bore the toothmarks.”

UPPER JAW.PALATE.UNDER JAW.THE TEETH OF THE GORILLA.

As the teeth of the Gorilla are admirably adapted for their duties of masticating and biting vegetable food, sometimes soft and sometimes hard, and as they resemble in number and general arrangement those of man, it is necessary to notice them briefly. They are of three kinds, the front ones, which bite when the jaw is moved up and down, the large eye teeth (or dog teeth), which pierce, and the back teeth, which crush and grind. The first-mentioned are called incisor teeth or cutters, and there are four in the upper and four in the lower jaw, as in man; the inner two in each jaw being larger than the outer two. They project slightly, and those of the upper jaw cut on the lower ones, and are, when the jaws are clenched, in front or “over-hung.” In shape they are adapted for biting a piece out of anything, and they have one fang each, which fits into a socket in the jaw. In the upper jaw there is a space between the incisor teeth and the great eye or dog teeth. This is one of the matters which distinguish the jaw of the Gorilla from that of man, whose teeth are continued in a row without any spaces where the gum is visible between them. The cause of the space is that the lower eye tooth is so large and long that when the mouth is closed it fits in there. This space is called a “diastema,” and, as it is a term which will often be mentioned, it is necessary to notice that it is taken from the Greek word διάστημα, “an interval.” In the lower jaw the incisor teeth are succeeded by the eye teeth without any diastema. The eye or dog teeth are usually called canines, fromCanis, a dog, they being very distinct in that animal. They are four in number, two being in each jaw, one on each side, and those of the upper jaw are long and pointed, being rounded, moreover, outside, and marked by grooves inside. The lower canines are nearly as large as the upper ones, and, as already noticed, fit in the diastema in front of those of the upper jaw.

Behind the canine teeth are, on each side in both jaws, five crushing teeth, that is to say, ten in each jaw, and twenty in all. In the upper jaw there is a continuous row of teeth from the canines in front to the last of the crushers, which occupy the position of the upper wisdom teeth of man, but in the lower jaw there is not this serried row of teeth, for, between the crushing ones and the canine, there is another space or diastema into which the upper canine tooth fits when the mouth is closed.

SKELETON OF THE GORILLA.

All these hind teeth are made to endure constant grinding, one over the other, in masticating, besides frequent shocks—as when nuts are cracked—and to last for years. Covered with a beautiful enamel, which gives them strength and smoothness, they are safely fixed by fangs in sockets in the bone, in such a manner that the nerves and blood-vessels supplying them do not suffer from pressure. They are not quite flat at the top, for then they could not grind, and they are not acutely sharp-pointed, for then the points would prevent the side-to-side movement of the jaw, and would be broken off; but they have rounded projections, or cusps, on them, separated by grooves, so that those of the teeth of one jaw can fit into those of the other. All these teeth are not quite alike, and they are divisible into two kinds, the three hinder ones being the molar teeth, fromMola, a mill-stone, and the two in front of them being called false molars or pre-molars (front molars). Every one who has had a back tooth (a molar) taken out, will remember its three fangs, and in a Gorilla there would be the same terrible wrench in extracting a molar for the same reasons as with us. But, fortunately for it, tooth decay is unknown, and the molars, with their three fangs, last as long as life. The pre-molars have two fangs only in man, but it appears that sometimes there are three to those teeth in the upper jaw of the Gorilla, and two only in the lower. They are smaller than the true molars or three back teeth, and in front of them; and that nearest the canine tooth is often tall, and almost like a four-sidedpyramid in shape. The size of the crushing or molar teeth is very distinctive of the Gorilla when it is compared with the other great man-like Apes, for the upper ones are equal in size, and in the lower jaw the hindmost tooth is larger than the others. Moreover, these lower teeth have five cusps or projections. There is a ridge extending obliquely across the crowns of the lower molars from an inner to an outer cusp; and the cross-like grooves of the upper surface of the corresponding teeth in man are not seen. The manner in which the teeth of the Gorilla differ from those of other Apes will be mentioned in the several descriptions. Milk teeth, or those of the first set, are found in baby and young Gorillas, and when they fall out the permanent set come out of the jaw and replace them, adding also to their numbers. The long canine teeth are characteristic of the old males, and those of the females and young are much smaller. The thirty-two teeth of the Gorilla, eminently adapted for a mixed vegetable diet, are therefore arranged as follows:—Upper jaw—four incisors, two canines, four pre-molars, and six true molars, and there is the same number in the lower jaw.

It is a very remarkable fact, and one which will be of some interest in comparing one of the other great Apes with the Gorilla, that the skull of the young Gorilla (of both sexes) and that of the full-grown female differs materially from that of the male in the absence of the prominent ridges of the top and back of the head. This gives a roundness to their skulls which would at first sight lead to the belief that they could not belong to the same species.

Living upon such nice things as sugar-canes and pine-apples, the Gorilla has a long and well-formed tongue to taste them with,[5]and a good nose to enjoy their scent and fragrance. The nostrils are open, and look downwards, being separated by a moderately wide piece of flesh covering, gristle, or cartilage, and they are protected above by very dense bones, which form the slight ridges called the nasal bones. Up the nose a passage leads to the air spaces in the bone of the front of the head, and they and some curiously curled bones not very far from the nostrils are covered with a delicate membrane well supplied with the nerves in which the function of smell exists.

Both the natives and Du Chaillu allude to the roaring and yelling of the old male Gorillas, and it will be noticed further on that the young ones can make noise enough. Dr. Savage was told that when the male is first seen he gives a terrific yell that resounds far and near through the forest, something likeKh—ah! Kh—ah, prolonged and shrill, and others have compared the noise to distant thunder. They have an organ of voice on the top of the windpipe, made on the plan of that of man, but deficient in many respects, and especially in those fine adaptations of structure which produce the human voice. But there is a very remarkable arrangement in their larynx, as it is called, which, although it has nothing to do with the formation of sound, may possibly make it more resonant and growling, and this is one of the things which separate the great Ape from man in matters of mere construction.

THROAT OF GORILLA.

At the back of our tongues, and also of those of the Gorilla, is a little flap, rather hard and gristly in us, and only membranous and soft in the Ape, which covers over the top of the air-passage into the windpipe when any food is swallowed. The food or drink would otherwise get into the air-passage, and would be constantly going “the wrong way.” Immediately under this flap, or, as it is called, the epiglottis, is a space limited in front by the hard substance we call in our throat the “Adam’s apple,” and at the bottom of it are the movable structures by whose action voice is produced. Now, in the this space is not shut in front as it is in us, but there are two openings in it, one on either side, which lead to a complicated sac or pouch. This pouch is made of thin membrane, and covers, when blown out like a bag—for the air coming out of the windpipe can be forced in—the front of the windpipe, and projects sideways under the muscles of the throat, and even amidst those of the armpits. The Gorilla can thus blow his neck out, as it were, and when he is yelling, the air in the bagor pouch must resound. Possibly this great bag of air may have something to do with making the body lighter when the animal is climbing and using all the force it can with its arms. These so-called “laryngeal” pouches are found in many Apes and Monkeys, but their double opening into the space below the little flap is peculiar to the great Apes, which are sufficiently man-like as to be called by the term Anthropoid—the Gorillas, their allies the Chimpanzees, the Orangs, and the Siamangs.[6]All the other Monkeys of the Old World with sacs have but one opening into a space, or, as it is termed, the ventricle of the organ of voice, or larynx. The Monkeys of the New World have a different arrangement of air pouches, which will be noticed in the proper place.

The Gorilla has one little peculiarity which distinguishes it from all other Apes and Monkeys, and which causes it to be more like man, and insignificant as it may seem, it is of some interest. In man there is a decided projection of bone behind, or rather below the ear, and this is called the teat-shaped process of the ear-bone (Mastoid process), and is of importance to the organ of hearing and also to the muscles which steady and keep the head erect, and allow of its being moved in particular directions. This process exists to a certain extent in the Gorilla but not in the Chimpanzee, Orang-Utan, or in any other of the Quadrumana. It is smaller in the Gorilla than in man, but it is made up, as in us, of a number of spaces enclosed by bones which have to do with the organ of hearing in some way or other, and which are lined with membrane. On the outside a muscle is attached, which passes downwards and inwards to the top of the breast-bone, covering the great blood-vessels and nerves of the neck.

In examining this process of bone, attention is of course drawn to the ear itself, and there is no doubt of the remarkable resemblance of those of man and of the Gorilla. The great Ape has evidently a very quick sense of hearing, for it gets out of the way of men as quickly as is possible, when it can only hear them in the forest and jungle, but that it should have the outside ear fashioned nearly after the resemblance of that beautiful structure in man is very remarkable. The ear of the Gorilla is smaller in proportion to the size of the head than those of other Apes, and is about the same length, but broader than that of man; the lobe, which is perforated by us for earrings, is perhaps less perfect in the Gorilla, but all the curves and folds, which are so complicated yet so graceful in the human ear exist in it, modified more or less, and not so harmonious in their general symmetry, as in man.

With all its great strength, the head of the great Ape cannot move as readily on the neck as that of weaker man, for the skull is not placed on the neck end of the back-bone quite in the same manner, and its position is not that which is admirably (as in us) adapted for carrying the head erect. One of the greatest marvels in the structure of man is the manner in which the tender mass of nerves called the spinal cord or marrow passes out of the hard skull into a bony canal down the spine, and yet does not suffer injury as head and back move and roll about.

The spinal cord or marrow passes out of the skull through a special opening, on the outside of which is a joint on either side. These joints fit on to corresponding ones on a ring-shaped bone (atlas bone), and this bone rests on one equally hollow, and which has an upward projection which enters the ring (axis bone), and is clasped to it by a strong ligament. It is this projection which prevents the spinal marrow from being injured by the head moving too freely, and yet life hangs almost on a thread, for were this strong ligament to break the soft nerve would be pressed in by the bony projection, and death would ensue. All the motions of the head are connected with these bones and their joints, and the way in which it is carried is in relation with the position of the opening in the skull for the spinal marrow. If the head is to be carried erect, as in man and in many birds, the opening is far from the back part of the head. If the face is to look upwards, as it does in a pig or dog, the opening is very far backwards. In the Gorilla it is not quite at the back, but further in that direction than in man, and hence the face of this Ape is more liable to be looking upwards than forwards. This is really the case, for the natural position of the animal is not erect, but on all-fours, and then it wants to look, not on the ground, but upwards and forwards, by tilting the head. Many of the great muscles of the back crest have to do with this. It is noticed also that the joint which permits the head to move on the ring-shaped bone (the atlas bone) is not so long or curved as in man, and therefore the movements of the Gorilla’s head are restricted.

All accounts of the life of a Gorilla tell of its moving rapidly amongst trees, climbing readily and noiselessly, and gathering its food constantly. It is therefore necessary to examine into the manner in which this is done, and how it relates to the shape and anatomy of the creature.

In climbing trees, the Gorilla, like a man under the same circumstances, lifts up the arms over the head, and clasps or holds on with one hand, but the position of the hand is not the same. Apes seize instinctively with the knuckles towards them, and not with the ends of the fingers and palm as man: and this makes a great difference, for the muscles of the back are therefore more important to the Ape than those of the chest in climbing. Then with some muscular effort the body is lifted or rather drawn up, so that the unemployed hand can reach and clasp higher than the other; and having thus two hands holding on to a bough or a tree, the muscles of both arms are used to draw up the ponderous trunk, head, and limbs until the face comes more or less on a level with the wrists. When this is accomplished, one of the arms is suddenly forced upwards to enable the huge grasp of the fingers to tighten upon a higher fixed point, and the “hand-over-hand” process is continued as long as is necessary. Doubtless the clasping feet assist in this movement, which is only rarely performed by man, but which is one of the commonest with the great Ape. A sailor or an acrobat may often use the muscles which are required to perform this feat of carrying upwards the body with the aid of the arms, but ordinary people rarely employ their energies in this manner; the Gorilla, on the contrary, must climb often and for some distance every day of its life, both for food, amusement, and for shelter. It becomes, therefore, an interesting question whether the Gorilla has any special muscles or bones which enable it to climb easily and rapidly, and for a considerable time, or whether there are the same kinds of bones and muscles in its hands, arms, and shoulders, which are to be found in man modified more or less. The results of careful inspection have proved that, although there are no peculiar structures given to the great Ape wherewith it may climb, still the bones of the arms and shoulders, and the muscles which are attached to them, greatly as they resemble those of man, are larger and stronger. Bone for bone, and almost muscle for muscle, the climbing limbs of the man and the Gorilla may be compared with extraordinary exactness; the structures of the last-mentioned being, as it were, simple exaggerations of the former, and the increased size bearing a distinct relation to the agility and energy displayed. It must be remembered, however, that whilst in man the muscles of the chest assist principally in climbing, in the Ape those of the back and shoulders are the most important.

FOREST IN THE GABOON COUNTRY—THE LAND OF THE GORILLA.

It is hardly necessary to notice the relation which bones and muscles have to movement, and themost unlearned in anatomy need only be reminded that muscles are adherent to certain parts of bones. The bone, by itself, is motionless, and the force which can move it, and with it, the surrounding flesh and skin, acts through the muscles, and these consist of vast numbers of long microscopic fibrils, placed side by side, and adherent, at both ends, to different bones. The fibrils have a vast amount of energy in them, and they can contract, or, in other words, shorten; the diminution in length being accompanied by a display of force. As the fibrils shorten, they tend to bring the motionless bones closer together, and to impart motion, which may be rapid, and more or less forcible. If one bone is stationary, the other may be brought towards it by the muscular contraction, or if both are not fixed, both may move. The nervous force produces the muscular contraction, whose vigour and lasting power depend a great deal upon the supply of blood sent to the fibrils through the blood vessels (arteries), and removed through the veins.

BONES OF THE FORE-ARM AND ARM OF THE GORILLA—SIDE VIEW.

SHOULDER OR BLADE-BONE.

In the principal act of climbing hand-over-hand, a bough or some stationary object is grasped by the fingers, the arm being straight, and the body hanging, as it were, to it. The first motion is the lifting up of the arm; the second is the grasping with the hand; and the third is the bending of the straight elbow, and bringing the shoulder up nearer the fixed point, or the part grasped. Whilst this is being done the body is not limp, but more or less stiffened by the spine, which runs down the back, and consists of many bones, being made rigid by the contraction of many small muscles. Now the bones and muscles of all the parts of the body engaged in climbing are so arranged that the spine shall not suffer any jarring, but shall be lifted up safely. Were all the muscles which pull upon the arms attached to it, every unusual effort would drag it almost to pieces, so there is a wide flat bone placed between the spine and the arm. This so-called blade-bone is jointed by a ball and socket joint to the arm-bone, but is only united to the spine and back part of the head by muscles. Muscles start from the spine to the blade-bone, from the blade-bone to the bones of the arm and fore-arm, and from these last to the bones of the fingers, and by their shortening or contraction, the fingers being stationary, the body is at last brought closer to them.

In order to explain the first motions of climbing, it is necessary to remark that on looking at the skeleton of the Gorilla the shoulder-blades are seen to be of the same general shape as those of man; they are much larger, however, and there are some anatomical points about them, which clearly have to do with the ability of the great Ape to keep its arms up for a long time, and to pull up its heavy body when the hands and fore-arms are fixed and immovable by clasping. One muscle, which in ourselves forms the cushion on the shoulder, and reaches down the outside of the arm for a little distance, is called the deltoid or Δ-shaped muscle, and its especial duty is, when the shoulder-blade is fixed, to lift up the arm by its contraction. The movement is permitted because between the spots where the muscles are adherent to the blade-bone on the one hand, and to the outside of the arm-bone on the other, a distance of several inches, there is a joint like a ball and socket. The muscle is notattached to a flat surface on the blade-bone, but to a raised edge, which runs rather obliquely, and is called the spine of the bone. Now this muscle is of immense importance to the Gorilla, as may be imagined from the nature of its function or office: it is placed in the same position as in man, and between the same kind of bones, but the spine of the blade-bone is longer, broader, and more slantingly set in the Ape, so that extra strength and greater power are attained.

This spine, or rather raised ridge, can be felt when we place the right hand over the left shoulder as far as possible, keeping the fingers between the neck and the end of the shoulder, and its slanting position can be traced best in the Gorilla; and it may be mentioned, that in the Chimpanzee the direction is much more oblique. Above this spine of the blade-bone there is the upper part of the blade, and it is covered with muscle, the space thus occupied being much larger in the Gorilla than in man. This muscle starts from this bone, to which it is attached, and is united to the arm-bone, close to its joint with the blade-bone; it is larger in the Gorilla than in us, and one of its uses is to assist the deltoid just mentioned.

There is rather an interesting arrangement in the old Gorillas, which is not found in the young or in man, and which appears to have to do with the power of this muscle and its prolonged action. The muscle is well supplied with blood, and the nerve which endows it with energy is particularly well prevented from being compressed during the movements of the muscles amongst which it runs, any compression being very injurious. The upper edge of the blade-bone is notched, and a dense tissue or ligament stretches from one point of the notch to the opposite one, enclosing a small open space; now the nerve runs through this space, and is protected by the hard tissues of bone and ligament from the contraction of the soft muscles. In the old Gorilla a further protection is found in the presence of a little projection of bone in this space, which acts as a greater preventer of pressure.

After passing through this space the nerve enters the very substance of the muscle, and is distributed to its fibrils.

The upper arm reaches down from the shoulder to the hips in the Gorilla, and its bone (os humerus, from the Latin) is strongly marked on its surface by roughnesses and ridges, to which the great muscles are attached. In man the shape of the upper arm varies with the strength of the individual, but in the strongest man and in the most beautifully-shaped woman it has a swelling on the front, and tapers more or less towards the elbow. This is caused by the two-headed or biceps muscle, and by other muscles ending in tendons. But the Gorilla has a very shapeless upper arm; it is, as it were, fat and round throughout, and very large above the elbow, and this is because of the size of the bone within, and on account of the muscles not tapering as they do in man, but being well developed right down to their ends. Hence, elegance of shape is sacrificed to extra muscular strength and size of bone.

On looking at the arm-bone, which, being connected to the shoulder by a joint, has much to do with the act of climbing and striking, it will be noticed that it greatly resembles that of man in shape, but is longer, stouter, and clumsier. The joint is nearly in the shape of a rounded knob, and the corresponding depression or cup on the blade or shoulder-bone into which it fits, is an oval and concave surface, and they are kept close together by a kind of capsule which stretches from one bone to the other and encloses the joint. Perfect freedom of movement is insured by the bones being covered with glistening cartilages, and a delicate and moist membrane, and the motion from the shape of the apparatus is almost equal to that of a chandelier where there is what is called a cup-and-ball joint at the ceiling. It has already been noticed that muscles are attached to the blade-bone and to the arm-bone below the joint, and that, this being movable, when they contract they move the arm, and the instance was given of the action of the deltoid muscle in raising the arm. In the Gorilla, this great muscle reaches lower down than in man, and there is a very strong mark in the shaft of the bone for its insertion. This gives the muscle greater play than in us, and enables it to lift, more slowly perhaps, but more efficiently, for the arm-bone between the joint and the place where the muscle is attached, is the long arm of a lever which is shorter in man. Below the globular head of the arm-bone is the shaft or cylindrical part of the bone which gives origin to the three-headed muscle called triceps, and is covered by the two-headed one (biceps) already mentioned, besides the deltoid. A deep groove allows one of the ends or heads of the biceps to pass along and slide over the joint and to reach the shoulder-blade. The shaft as a whole is more or less cylindrical, with a slight angular outline, the angles being projections ofbone which strengthen the whole, besides giving attachment to muscles; the cylindrical shape is the best for strength and lightness, and these properties are increased by the adoption of a plan which engineers have long since unwittingly copied. The shaft is hollow, and is cellular at both ends, solid bone covering the outside, conditions which oppose fracture, and produce increased strength, indeed greater strength and lightness than a solid bone would have. Below the shaft is an expansion, on which are placed the surfaces for the jointing on of the two bones of the fore-arm, and the bone is especially in old Gorillas perforated there, a condition seen in some very old human bones. There is an important point in the relative length of the upper arm-bone, and the bones of the fore-arm in the Gorilla, in other Apes, and in man, for in this great Ape and in us the humerus is longer than the others, and in the Chimpanzee they are almost equal, whilst in the rest of the Monkeys they are very unequal, the bones of the fore-arm being much the longest.

Although they have such strong arms, covered with a stout skin and with hairs sloping downwards, the Gorillas sometimes manage to break them, and then Nature endeavours to repair the injury. In the skeleton of the old male Gorilla in the British Museum there are proofs of a former fracture of the humerus or upper arm-bone. The arm was broken across, and as it could not be kept quiet, Dame Nature has not done her work as well as a modern surgeon could on a patient whose arm he could put in splints, for it is thickened, shortened, and twisted.

The fore-arm of the Gorilla has its long hairs pointing upwards to the elbow, and the limb does not slope gracefully towards, and become slightly smaller above the wrist, as in man, but remains thick and fleshy as far as the hand. There are two bones in the forearm which are jointed above with the lower end of the arm-bone (humerus), and which are also connected by joints at their lower ends with the small bones forming part of the wrist. The bones of the fore-arm are called the radius and the ulna in the Gorilla as in man. They are larger, stouter, and wider apart in the great Ape than in ordinary Europeans, but they greatly resemble those of the Australian aborigines. As these bones are covered with muscles, some going to the fingers, and others coming from the upper arm, there are many ridges or surfaces on them, for their origin and attachment, and these greatly resemble those of man; moreover, the muscles perform the same functions and movements.

When compared with that of a strong man, the wrist of the Gorilla is broader, and the bones, of the same number, are larger from side to side, and this extra breadth makes this part of the hand very wide. As the Gorilla’s hand often has to support the weight of the body, on the back of the fingers and knuckles, it is long, broad, and very strong, surpassing in these respects those of man; but the thumb is peculiar. It does not look a well-formed one; it is evidently short, and out of proportion to the long fingers. The human thumb reaches not far from the second joint of the fore-finger; but the top of that of the Gorilla is on a level with the first joint, or at the end of the long bones of the hand, and which are called metacarpal bones.

Remarkable then for its breadth and thickness, the Gorilla’s hand has also a long palm, which is not only due to the length of the bones, just mentioned, but also to the fact that the web or undivided skin between the fingers, where they join the hand, is not slight as in man, but long and very decidedly visible. The web extends half way up the first joint of the fingers. The fingers are therefore made to appear short[7](although their bones are long), and they look dumpy and swollen, and this appearance is increased by there being callous pads of skin on the back of the middle and end joints. Finally, the fingers slope to the nails, which are not much larger or longer than those of man. The back of the hand is hairy as far as the divisions of the fingers; and the callous pads, just noticed, almost do away with the appearance of some of the joints. The short thumb, not so big as the forefinger, has a nail which does not reach the end of it, and the under-parts of the thumb, fingers, and palm have a bare skin. Professor Owen, in summing up the difference between the structure of the hands of the Gorilla and of man, remarks that in the great Ape the hands are instruments for great power of grasp, and for sustaining great weight, and the length and strength of the whole upper limb accord with their mechanical powers and requirements. In man, the framework of the hand bespeaks an organ of varied and delicate prehension, and the form and proportion of the rest of the arm-limb relate to the free motions and complex functions of the instrument.

Having raised the arm by its muscles, the fingers and thumbs grasp an object, or, in other words, certain muscles which are placed between the bones of the fingers and between the fingers and the bones of the fore-arm, contract and move the bones, which are jointed. The tops of the fingers are bent on the palm, and the thumb is closed on them, and this continues as long as the contraction permits. All the apparatus for long-continued clasping is present in the Gorilla, and there are nearly the same kinds of muscles employed as in man. There are, however, some differences, to one of which it is necessary now to allude. The thumb, for instance, of the Gorilla is of great importance in grasping, but it has not to perform such complicated movements in other things as that of man. In man its movements are most wonderful, and by using one muscle after the other which belongs to it, it can be moved so as to describe a circle with its tip. This is done in the action of “twiddling,” but also in many others where the will hardly influences the muscle, and where the thumb may be said to be moved unconsciously. Gorillas in their quietest and most reflective moods cannot indulge in the sober practice of twiddling, for an important twiddling muscle is absent in them. But it is no great loss, and perhaps it is a real gain, for this muscle would be in the way of rapid clasping, as it rather tends to keep the thumb from the fingers. Whilst the great Ape is thus deficient it has a muscle on the other side of the hand which is not possessed by man, and whose office appears to be to separate as far as is possible the fourth and fifth fingers (their first joints), and by so doing to enlarge the grasp of the whole hand. As the hand of the Gorilla is at least a third larger than that of the averaged-sized man, there is of course a corresponding increase in the space which can be grasped. The muscles are stronger and stouter than in us, and therefore the hand is a more powerful one. Nevertheless it is incompetent of performing many actions which are readily done by a child.

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