I cannot accept the theory that _os centrale carpi_ is merely a

detached portion of the scaphoid bone. In a very young chimpanzee this

bone is undoubtedly superficially indented with two transverse furrows,

but the three segments display only one uniform development of bone.

The distinct formation of _os centrale_, and its occasional appearance

in man, testify that it has an independent existence. Rosenberg

holds that this bone is not merely the _os centrale_ of mammals, but

that it is homologous with the two _ossa centralia_ of the fossil

_Enaliosauria_. It has become abortive in proportion to the reduction

in size which has taken place.[52] There would be no great difficulty

in tracing back this bone to remote types of vertebrate animals,

even as far as the _Urodela_ (Wiedersheim) of Eastern Asia.[53] The

persistence of this bone in man must be regarded as a reversion, not as

an arrest, of development.

[Illustration:

Fig. 42.--Skeleton of human hand, back view. _a_, Scaphoid bone.

_b_, Semi-lunar bone. _c_, Cuneiform bone. _d_, Pisiform bone.

_e_, Trapezium. _f_, Trapezoid bone. _g_, Os magnum. _h_,

Unciform bone. _l-l′_, Metacarpal bones. _m-m′_ and _nn_,

Phalanges.

]

On the femur of several mammals, especially in the horse, ass,

rhinoceros, and tapir, and more slightly indicated in the carnivora

and other families, there is, in addition to the two great and small

trochanters, a third, termed by Waldeyer _trochanter tertius_.[54]

Such a formation, low, blunt, and generally placed at the top of the

outer ridge of the superior bifurcation of the _linea aspera_, may

be observed in human skeletons of all races, but is either absent in

anthropoids or only faintly indicated. Virchow justly regards its

presence as theromorphic, but not as a characteristic of savage or

lower races.[55]

The human tibia displays in some instances a compression or lateral

flattening of its shaft or centre-piece, so that its transverse

diameter is quite out of proportion to its depth. Such a tibia is

termed sword-bladed, or platycnemic. Bones of this form have been

chiefly discovered in ancient deposits, as, for instance, at Gibraltar,

at Perthi-Chwareu, in Wiltshire, in Lozère, at Clichy, at Saint-Suzanne

(Sarthe), and especially at Cro-Magnon (Fig. 43), Janischwek, etc.

A similar formation has also been observed among men belonging to

cultured races, both of ancient and modern times. Virchow, for example,

discovered such bones in Transcaucasia (of the third and fourth century

of the Christian era) and at Hanai-Tepe in Troas. All the large

schools of anatomy in Europe contain specimens of tibiæ, which are to

some extent platycnemic. These are also observed in the skeletons of

primitive peoples of our time, as for example in the Negritos, Kanakas,

and other African races. While some scientific men regard these bones

as the result of an unhealthy condition, and the effect of rachitis,

others more justly ascribe them to a vigorous exercise of the muscles

in a one-sided direction. The idea expressed by Busk and others, that

the platycnemic tibiæ discovered in ancient sites of Europe have

belonged to a degraded race diffused over the whole continent, is

contradicted by the wide diffusion of this characteristic, even in

modern times. And it is doubtful whether platycnemy is absolutely

restricted to the lower races. At Janischewek, Virchow found an

extremely platycnemic tibia, exhumed from a kujawish grave of the Stone

Age, which belonged to a skull remarkable for its unusual beauty and

size, so that, taken by itself, the impression which it gave to an

anatomist was that of a highly organized race.[56]

[Illustration:

Fig. 43. Section through a platycnemic tibia from Cro-Magnon.

Fig. 44. Section through the tibia of a male gorilla.

Fig. 45. Section through the tibia of a male chimpanzee.

]

It is important to remark that platycnemy has been regarded as a

pithecoid structure, and for this reason the attempt has been made

to establish the degraded position of those peoples which are most

remarkable for platycnemy. But, as Boyd-Dawkins has already observed,

although the tibiæ of the gorilla and the chimpanzee are to some

extent platycnemic, they are much less so than the platycnemic bones

of the human skeleton. The tibia of a male gorilla in the College of

Surgeons Museum has an index width of 68·1, that of a female of 65·0,

while the index of the chimpanzee’s tibia is 61·1, which is about the

average of the tibias of Perthichwareu. It is unnecessary to indicate

the other marked distinctions between the tibiæ of men and apes; if

platycnemy is to be regarded as genetic, it must be admitted that man

has in this particular far exceeded apes.[57] Neither the gorilla,

the chimpanzee, the orang-utan, nor even the baboon possesses a tibia

which is flattened in its upper or middle part. In all these apes the

middle of the bone is more or less rounded, almost as if it had been

rounded by a turning-lathe. According to my experience, the degree of

platycnemy in anthropoids is subject to certain variations. It appears

to me to be least marked in the aged male gorilla (Fig. 41), and in

the gibbon (_Hylobates agilis_, _syndactylus_), in which latter animal

the transverse section of the tibia represents an almost equilateral

triangle. The platycnemy was more marked in an almost adult female

gorilla, still more decided in an aged male chimpanzee, which came

from the river Kiulu, and again in an aged female chimpanzee. On the

other hand, the centre of the shaft of the tibia in another aged male

chimpanzee which came from Loango, was rounded, and not platycnemic. In

the tibia of an adult orang-utan which I examined, the platycnemy was

very marked. But I agree with Boyd-Dawkins in never having met with an

anthropoid in which the platycnemy is so considerable as it is, for

instance, in the Cro-Magnon tibia, and in another found at Troy.

[Illustration:

Fig. 46.--Skeleton of the human foot, seen from above. _a_,

Astragalus. _b_, Os calcis. _c_, Scaphoid bone. _d_, _e_, _f_,

Cuneiform bones. _g_, Cuboid bone. _h_, Metatarsal bones. _ii_,

Phalanges.

]

If we give a cursory glance at the lower limbs of apes, we see that all

the same characteristics are present in their tarsus that we find in

the human tarsus. In each case there is an astragalus, an _os calcis_,

a scaphoid bone, three cuneiform bones, and a cuboid bone. There are

undoubtedly several peculiarities in which the tarsus differs from

the corresponding part of the human foot. The first metatarsal bone

is joined to the first cuneiform bone by an articular facet which

extends from the back to the sole of the foot. This joint plays a part

resembling that of the thumb of the human hand (see Figs. 20 and 46).

In Huxley’s opinion, the hinder limbs of the gorilla terminate in

a true foot, with a very movable great toe. It is undoubtedly a

prehensile foot, but in no sense a hand. It is a foot which does not

differ from the human foot in any essential characteristics, but only

in relative circumstances, in the degree of flexibility, and in the

subordinate arrangements of its parts. Huxley adds that it must not

be supposed that he wishes to undervalue differences which, however,

he does not regard as fundamental. They are important enough of

their kind, since in any case the structure of the foot is in close

correlation with the other parts of the organism. Although it cannot be

doubted that the increased division of labour in man, which relegates

the function of support entirely to the legs and feet, is a significant

advance in structure; yet, regarded as a whole from the anatomical

point of view, the points of agreement between the human foot and

that of the gorilla are much more striking and significant than their

differences.

The differences in the foot of the orang are still greater; in the very

long toes and short tarsus, the short great toe and the removal of

the heel from the ground, in the great obliquity of the joints which

connect the foot with the shank-bones, and in the absence of a long

flexor muscle to move the great toe, the orang’s foot differs still

more from that of the gorilla than the latter differs from the human

foot. In some of the lower apes the hands and feet are still further

removed from those of the gorilla than in the case of the orang. In the

American apes the thumb can no longer be opposed; in the ateles it is

reduced to a mere rudiment, covered with skin; in the sahius it is bent

forwards and provided with a curved claw like the other fingers. In all

these cases there is no doubt that the hand differs more from that of

the gorilla than the gorilla’s hand differs from that of man.[58]

Flower remarks that the chief distinction between the foot of a man

and an ape consists in the fact that the latter is transformed into a

prehensile organ. The tarsal and metatarsal bones, and the phalanges

are of the same number in both orders, and in the same relative

position, only in the foot of the ape the facet for articulation of

the first cuneiform bone with the great toe is saddle-shaped, and

obliquely directed towards the inner or tibial side of the foot. Thus,

the great toe is separated from the others, and so placed, that when

it is bent, it is directed downwards towards the sole, and is opposed

to the other toes, much more opposed to them than is the case with the

thumb of the human hand.[59] Owen also speaks of the characteristic

transformation of the great toe of an ape’s foot into a thumb, opposed

to the other toes, and adapted for grasping.[60]

[Illustration: Fig. 47.--Coaita (_Ateles paniscus_).]

K. E. von Bär does not agree with Huxley in considering that there is

less difference between man and the gorilla than that which exists

between different species of apes. “There are,” Von Bär remarks,

“differences of various kinds among apes. In some the thumb is only

a stump; in others, as in the orang-utan, the fingers of the hinder

extremities are so long and curved that they cannot be extended on flat

ground; in many of the smaller apes this member is still more like a

hand than in the larger species, and the fingers can be easily spread

out on the ground. In this case the foot is of a much blunter form, and

is more flexible, so that the sole, which is properly turned inward,

can lie flat on the ground. The heavier the body of the animal, the

more sharply cut the structure of the foot must be, so that it does

not admit of the free movements which are possible in the hand. But

all these are only modifications of a climbing foot, or prehensile

member--that is, of a hand, not modifications of a foot resting firmly

on the ground and supporting the whole weight of the body.

“It must not be forgotten that the structure of the skeleton is subject

to mechanical laws, which may be traced through the whole series of

the animal world. This is readily apparent when we turn to the human

structure.

“The human foot rests for the greater part of its length on the

ground, that is to say, with the heel and centre of the foot, which

form together a firm arch. The tarsus consists of the astragalus, and

also of the _os calcis_, which in man form a very prominent part,

taking a backward and downward direction, and of five other bones.

The metatarsus consists of five bones, on which the five toes are

inserted. In man these metatarsal bones are considerably longer than

the separate phalanges. Thus, the arch on which man is supported in

an erect position extends from the heel to the extremities of the

metatarsal bones. The several bones are slightly movable, but they are

so firmly connected that they can diverge but little from each other,

unless muscular power is exerted. In order to press the toes upon the

ground, it is again necessary to exert the muscles. The arched instep

has this advantage, that the foot can take a better hold of the slight

inequalities of the ground. In a profile view of the skeleton of a

human foot, the shortness of the toes, in comparison with the length of

the arched instep, is very apparent. In any natural position, even when

man is not walking or standing, the sole of the foot is not turned

inwards, but downwards.... The toes of the gorilla take the form of

a hand, since the great toe stands separate like a thumb, while the

other toes are turned outwards. In the gorilla the tarsus is short,

and the heel is bent inwards. The several bones of the human foot are

undoubtedly present in the hind hand of a gorilla, but the organ is

changed into a prehensile organ or hand. The conditions are the same as

in the parts of the mouth in insects which in some cases form movable

mandibles, while in others they are attenuated into a proboscis. When

it is asserted that apes are not quadrumanous, it is as if we were to

say that flies have no proboscis, but attenuated mandibles.”[61]

All apes, including anthropoids, occasionally make use of their hinder

extremities in order to snatch at objects. They also grasp with them in

climbing. On such occasions, when they wish to secure the fruit they

have seized from the voracity of their fellows, they take it between

the toes of one hinder extremity, in order to be able to get away more

quickly by means of the other, and by the use of both hands.

From what we have said, it will be seen how difficult it is to

reconcile the views of different observers with respect to the fitting

term to be given to the hinder extremities of apes. Against those who

uphold the designation of _hind hands_ we must oppose the anatomical

structure, and also the fact that a true hand ought to possess the

power of rotation in a degree which exists in the fore, but not in the

hind, extremities of apes. On this account I have already adopted, as

more suitable and equally distinctive, the term of _prehensile foot_

for this member.[62] I agree with Haeckel in rejecting the common

designation of apes as four-handed or quadrumanous.

The bands or ligaments which connect the different parts of the

anthropoid skeleton together, and convert the detached elements into

a movable machinery, do not on the whole differ much from the same

structure in man. A detailed account of these ligaments would, for

several reasons, be out of place in this work, and I shall only mention

a few special and more interesting distinctions. Such, for example,

is the uncommon strength of the _ligamentum nuchæ_ in the gorilla,

which is quite in harmony with the great development of the spinous

processes of the upper cervical vertebræ, and with the flattening of

the squamous occipital portion. Since the sacral vertebræ are deeply

inserted between the high ilia, the ilio-lumbar ligaments (_ligamenta

iliolumbalia_) and the sacro-iliac ligaments (_ligamenta iliosacralia_)

are of considerable size. In agreement with the projection in a

downward direction of the high, narrow ischial bones, the sacro-sciatic

ligaments which extend between these and the sacrum are very long

in the chimpanzee. Although in this case the ischial spine is only

represented by a roughness of the bone, yet there is on either side

between this and the sacrum a powerful lesser sacro-sciatic ligament

(_ligamentum spinoso-sacrum_).

The well-known anatomist, J. F. Meckel, has asserted that the

depression in the head of the femur (_fovea capitis_), which serves for

the insertion of the round ligament (_ligamentum teres_), is absent in

the chimpanzee and orang, and he adds that it is also absent in the

gibbon. In a skeleton of a young chimpanzee which had not shed its

milk-teeth, and of which the ligaments were also preserved, Welcker

found a fully developed round ligament inserted almost in the centre of

the head of the femur. This agrees in every particular with the same

formation in man. On the other hand, no trace of a round ligament was

to be found in the hip-joint of a young orang-utan. The cartilaginous

envelope of the head of the femur was smooth throughout, without any

indication of a place for inserting the ligament. Welcker again found

no such depression in the femur of an aged male orang-utan, nor was

there any trace of it in another aged male orang, designated as _Simia

Morio_. Welcker believes that he has established the fact that the

round ligament is wanting in the orang-utan, but that it is present in

the gorilla, chimpanzee, and gibbon. The same naturalist remarks that,

although we may certainly assume that the round ligament is absent

wherever there is no depression in the head of the femur, yet the

existence of such a depression in the acetabulum (_fovea acetabuli_)

is not enough to prove that a round ligament was inserted in it. The

innominate bones of an adult orang-utan were examined by Welcker, and

displayed a small, but well-defined depression, as if destined for

a receptacle for this ligament,[63] running from the cotyloid notch

down to the bottom of the acetabulum, between the two horns of the

semilunar-shaped articular cartilage.

In a subsequent paper, Welcker states that the absence of the round

ligament in the orang-utan, and its presence in the chimpanzee, had

been previously established by Camper and Owen.[64] In three specimens

of orangs which he had obtained immediately after death, Owen found

that the round ligament was imperfectly developed on both sides. The

chimpanzee differs from the orang in possessing a depression on the

head of the femur. In the gorilla, as Owen observes, this depression

has almost the same depth and relative position as in man. At Welcker’s

request, Professor Dippel ascertained the presence of the depression

in the femur of a gorilla skeleton which is preserved in the natural

history collection at Darmstadt. St. George Mivart saw the skeleton

of an orang in which the femur was marked with a slight but plainly

indicated depression, just where the round ligament is usually

attached. Welcker thinks it probable that in some specimens of the

gorilla the round ligament is only slightly developed, and that in

others it is altogether wanting. On several femurs of gorillas, this

naturalist observed only doubtful traces of the depression in question.

Duvernoy found the round ligament fully developed in the gorilla and

chimpanzee. Vrolik failed to find it in the orang-utan, but ascertained

its presence in the chimpanzee. Gratiolet and Alix saw that it was

fully developed in _Troglodytes Aubryi_.

In addition to these somewhat conflicting assertions, I have myself

observed, in the gorilla innominate and femur bones examined by me,

more or less distinct indications of the depression which receives

the round ligament. The ligament itself has been preserved with the

body of a gorilla. The same remark applies to the skeletons and

bodies of chimpanzees. In the case of the skeleton of an orang,

slight indications of a depression were observed on the head of the

left femur, and these indications were absent in the femurs of other

specimens. In a large orang-utan which died in the Berlin Aquarium,

only short, filamentous tufts of streaky fibres were apparent in the

right acetabulum, and these were intermingled singly or in groups

with the cartilaginous cells, somewhat resembling the cartilaginous

corpuscles of the synovial membrane. From these facts we may conclude

that the round ligament is generally but not invariably present in

the gorilla and chimpanzee, and that it is altogether absent in the

orang-utan. In the gibbon it is present in the majority of cases.

I have myself observed it in _Hylobates agilis_, _leuciscus_, and

_syndactylus_. Owen asserts that the unsteady gait of the orang is

partly due to the absence of this ligament, but the truth of this

surmise is rendered doubtful by the fact that the ligament is not

unfrequently absent in other anthropoids. Moreover, the gait of all

these arboreal and climbing animals is extremely ungainly.

The muscular system of anthropoid apes is very interesting. I must

necessarily refrain from giving a detailed account of it, and will only

mention some points in connection with this organic system, and their

relation to corresponding points in the muscular system of man. I rely

partly on the researches of others, and partly on my own. The amount of

material which has been collected up to this time is, unfortunately,

too scanty to enable us to draw satisfactory conclusions in all cases.

We are often unable to decide whether the conditions presented to us

in the case of anthropoids are normal or exceptional. Nor are the

statistics of muscular variations in the human subject by any means

firmly established. My own labours in this direction are not yet

concluded. The assertions on the subject which have been published to

the world and accepted as authoritative have already been shown to be

to some extent untrustworthy. Even the little which I am now able to

produce may not altogether stand the test of subsequent research. Brühl

justly remarks that in no department of anatomy more than in that which

treats of the muscles, is it more essential that we should not decide

whether a form is normal or exceptional until it has been repeatedly

examined.[65]

[Illustration:

Fig. 48.--Muscles of the head and face of a European. 1,

1′, Occipito-frontalis. 2, 3, Orbicularis palpebrarum. 4,

Pyramidalis nasi. 5, Levator labii superioris alæque nasi. 6,

Compressor naris. 7, Levator labii superioris. 7′, Zygomaticus

minor. 8, Levator anguli oris. 8′, Zygomaticus major. 9,

Orbicularis oris. 9′, Levator menti. 9″, Depressor labii

inferioris. 10, Depressor anguli oris. 11, Masseter. 12,

13, Risorius and the buccinator by which it is covered. 15,

Trapezius. 16, Attrahens. 17, 19, Attollens. 20, Retrahens

aurem. 21, Sterno-mastoid. 22, Splenius. A. Tendinous

aponeurosis. C. Malar bone (the parotis is removed). F. Skin of

neck.

]

The cranial muscles of anthropoids are formed like those of men,

except in a few unimportant particulars (comp. Figs. 48 and 50). I have

not observed in anthropoids the muscular fibres which in man branch

out from the orbicular muscle of the eye, and overlap the cheeks and

temples, and which are considerably developed in the head of a Monjalo

negro which was dissected by me (Fig. 49, ~3~, ~3′~). In apes that

portion of the orbicular muscle which covers the supra-orbital ridge

is very marked. There is generally a considerable layer of muscle on

the nose and upper lip. I have dissected it in detail in anthropoid and

other apes, including those of America; _i.e._ the zygomatic muscles,

the levator labii superioris, and the levator labii superioris alæque

nasi. This has also been done by Duvernoy, Alix, and Gratiolet, in the

case of anthropoids dissected by them, as well as by Macalister and

Bischoff.

[Illustration:

Fig. 49.--Head-muscles of a Monjalese negro. 1, 2,

Occipito-frontalis. 3, 3′, Orbicularis palpebrarum. 4,

Pyramidalis nasi. 4′, Levator labii superioris. 6, Levator

labii superioris alæque nasi. 6′, Compressor naris. 7′, Levator

anguli oris. 8, 8′, Zygomatici major et minor. 9, Orbicularis

oris. 9′, Levator menti. 9″, Depressor labii inferioris. 9‴,

Depressor anguli oris. 11, Masseter. 13, Buccinator. 14,

Platysma. 15, Trapezius. 17, 18, Attollens and attrahens

aurem. 19, Embedded temporal muscle. 20, Retrahens aurem. 21,

Sterno-mastoid. 22, Deeply set muscles of neck. A, Tendinous

aponeurosis. C, Zygoma. E, Parotis. *, Stensonian duct.

]

Bischoff was only able to identify a wide zygomatic muscle in the

orang with the small zygomatic in man. In the orang, the gibbon, and

the baboon, as well as in _Innus sinicus_ and _Ateles_, I myself was

quite able to trace a division into a large and small zygomatic. In the

gorilla dissected by me the levator labii superioris alæque nasi was

very wide (Fig. 50, ~6~). In the case of a gorilla, Ehlers dissected

the small zygomatic muscle, together with the levator labii superioris

alæque nasi, in the manner introduced by Henle as a single square

muscle of the upper lip (_Musculus quadratus labii superioris_). In the

gorilla I observed a levator alæque nasi, together with the already

mentioned levator labii superioris; but I failed to find any separate

levator labii superioris. The very wide cartilage of the nose is

occupied by a considerable amount of muscular tissue. All these muscles

are present in the orang, but they are of small size and separated

into detached bundles. The pyramidalis nasi may be traced in every

instance, especially in the gorilla (Fig. 50, ~4~) and in the orang. It

is not so strongly developed in the chimpanzee and gibbon, but is not

absent in these apes, nor in those which are not anthropoid, such as

the baboon, and ateles, or climbing ape.

[Illustration:

Fig. 50.--Head-muscles of gorilla presented in Fig. 3. 1,

2, Occipito-frontalis. 3, 3′, Orbicularis palpebrarum. 4,

Pyramidalis nasi. 5, Levator alæ nasi. 6, Levator labii

superioris alæque nasi. 7, Zygomaticus minor. 7′, Levator

anguli oris. 8, Zygomaticus major. 9, 9′, Orbicularis oris.

10, Risorius. 11, 16, Masseter. 1′, Buccinator. 12, Depressor

anguli oris. 13, Buccinator. 14, Platysma. 15, Trapezius. 17,

Temporal. 18, 19, 20, Attrahens, attollens, and retrahens

aurem. 21, Lesser muscle of helix. A, Tendinous aponeurosis. B,

Cartilage of nostril. C, Zygoma. D, External ear. *, Stensonian

duct.

]

I myself follow the original division of the muscles into those which

belong to the nostril and upper lip, in accordance with the principles

of Duchenne, Darwin, Gamba,[66] and others, and I do so the more

readily, since it is impossible not to perceive the manifold and lively

mimetic action which takes place in this particular region of an ape’s

head. The distinct action of the levator labii superioris alæque nasi,

the dilation of the nostrils, the function of a strongly developed

levator anguli oris, are especially characteristic of the gorilla; but

they are also perceptible in the chimpanzee and gibbon. The orang’s

face is the least mobile. I observed that in the gorilla the risorius

was very long, branching slightly in the fore-part of the corner of the

mouth, and behind into three distinct wide bundles. The lowest bundle

covered the platysma myoides, but could not be regarded as part of

the latter. In one chimpanzee I found that the risorius was slightly

developed, and in other animals of that species I failed to trace it

at all. Alix and Gratiolet represent the Aubry chimpanzee (Plate ix.

Fig. 1, ~15~) with the risorius strongly developed. I have not observed

this formation either in the orang or the gibbon, but it was apparent

in one of the ateles (_Ateles leucophthalmos_). In this case the muscle

covered the platysma myoides and Stenson’s duct, _i.e._ the duct

leading out of the parotid gland (Fig. 50, *).

For some time I was disposed to regard the risorius of this ape as only

a radiation of the platysma myoides, but my opinion upon this point is

again shaken.

In the gorilla a faint depressor anguli oris and an equally faint

depressor labii inferioris may be observed, the latter partly covered

by the large and predominant orbicularis oris (Fig. 50). In the

chimpanzee the two depressors are plainly apparent, and in the gibbon

the one first named was at any rate developed. The platysma myoides,

the depressors just mentioned, and the crescent-shaped orbiculares

are in this animal in close connection with each other. Froriep’s

suggestion becomes ever more probable, that these muscles of the lower

lip owe their origin to the intersection of the opposite portions of

the skin-muscles of the neck which overlap the face. The buccinator

muscle in anthropoids resembles on the whole that of man, and in

both cases is pierced by Stenson’s duct (Fig. 50). The form of the

masseter muscle is common to both (see Fig. 50, ~11, 16~). In the

external ear of anthropoids there is an attrahens, attollens, retrahens

(Fig. 50). Compared with that of a white man, and still more with

that of a negro (see Figs. 48, ~19~, and 49, ~17~), the attollens

is only slightly developed. The muscles attached to the cartilages

of the ear are extremely scanty or partially wanting, which is also

sometimes the case with man. The muscles of the helix are most strongly

marked in the gorilla (see, for example, Fig. 50, ~21~). Tiedemann,

Bischoff’s brother-in-law, carefully observed two living chimpanzees

in Philadelphia for six months without detecting any movement of the

ears. My own observation confirms his assertion and the remarks of

Darwin, which I have already quoted, to the effect that anthropoids are

incapable of moving their ears. I know of no individual exceptions.

This is the more remarkable since some men have retained the power of

voluntarily moving their ears, and the same power is also found in some

species of apes, such as the sea-cats, baboons, macacas, and magots.

It will not here be out of place to say something of the

characteristics, previously mentioned, of the physiognomical expression

of anthropoid apes. Thus, for example, when the gorilla is agitated, he

can move the skin of his head and bristle the hair which covers this

region. The chimpanzee can also move the skin of the head, but with no

very apparent bristling of the hair. The large male orang, which was in

the Berlin Aquarium in 1876, bristled his hair and the skin of his head

when he was much enraged. It is known that in some instances man also

possesses this power.

I have already spoken of the expression of the eyes of these animals. I

will only add that when anthropoids of every species are in great pain

or seriously ill, the expression of their eyes is often most affecting.

The forehead of these animals is frequently marked by transverse

furrows, and especially, as Darwin justly observes, when they raise

their eyebrows. The same great observer considers that the countenances

of anthropoids are, in comparison with those of men, generally

inexpressive, and indeed, chiefly in consequence of the fact that they

do not wrinkle the forehead when they are excited. The wrinkling of

the forehead, which is one of the most significant forms of expression

in man, is due to the action of the corrugatores supercilii, by which

the eyebrows are drawn down and closer to each other, so as to form

vertical folds on the forehead. It has been asserted that the orang

and chimpanzee possess these muscles, but they seem to be rarely

exercised--at any rate, to any remarkable extent.[67] When Darwin

brought a chimpanzee out of his dark chamber into bright sunshine, he

only once observed a slight wrinkling of the forehead. When the same

observer tickled the nose of a chimpanzee with a straw, its face was

slightly wrinkled, and faint vertical furrows appeared between the

eyebrows.[68] Darwin never observed any wrinkling of the forehead in

an orang. I myself have observed a contraction of that region of the

brows which is covered with bristly hairs, and a wrinkling of the skin

which covers the bridge of the nose in the gorilla and the chimpanzee,

and have illustrated this expression by a drawing.

Darwin goes on to say that when a young chimpanzee is tickled, to

which, as in the case of children, their armpits are peculiarly

sensitive, he generally utters a chuckling or laughing sound, although

sometimes the laugh is silent. The corners of the mouth are then drawn

back, and this sometimes causes the eyelids to be slightly wrinkled.

This wrinkling, which is so characteristic of the human laugh, is still

more apparent in some of the other apes. In the chimpanzee the teeth of

the upper jaw are not exposed when he utters this laughing sound, and

in this respect he differs from man. Darwin further observes that when

the tickled young orang ceases to laugh, an expression passes over his

face, which, according to Wallace, may be called a smile. Darwin has

observed something similar in the chimpanzee.[69]

My own observation confirms what has been said of the chuckling

of a tickled chimpanzee. When Dr. Hermes, the director of the

Berlin Aquarium, played with the chimpanzee which was kept in that

establishment, a contortion of the corner of the mouth, resembling

a somewhat sardonic smile, at once appeared. No specimen displayed

this smile with so much effect as the lively Augustus, who delighted

visitors by his inexhaustible humour in 1879. The gorilla, of which

an illustration is given in Fig. 3, also drew down the corner of his

mouth when he was pleased, by means of the muscular system which we

have just described.

When the gorilla is provoked, he displays both rows of teeth, and opens

his mouth to utter sounds of fury, while making ready to fight. It is

well known that anthropoids are able to pout and project their lips;

and Darwin says that they do this, not only when they are slightly

teased, and are sullen or disappointed, but also when anything occurs

to make them uneasy.

I have often observed in chimpanzees a slight wrinkling of the region

of the nasal cartilage, and even a vibration in a lateral and upward

direction. In any case, the muscles which we have described as acting

on the nose and upper lip are exercised.

The platysma myoides, which extends in man from the lower row of teeth

to just below the clavicle, occupies about the same area in the gibbon

and in other apes (Fig. 50). In the chimpanzee, however, this muscle

extends as high as the zygomatic arch, or even higher. In the gorilla

also I observed that this part extends comparatively high on the face.

In chimpanzees, orangs, and gibbons the upper fibres of this muscle

seem to form the risorius. In one case the platysma myoides sent forth

a fasciculus, about 18 mm. in width, to the beginning of the lower

temporal ridges. In the gorilla I saw that the uppermost fibres of the

platysma myoides were partly covered by the risorius (Fig. 50, ~10~).

From the corresponding muscle in the orang the lower fibres tend far

backward, and are in connection with the deltoid muscle covering a

segment of the capsular ligament. This muscle wrinkles the skin of

the neck, and helps to draw down the lower jaw. In cases in which it

extends far in an upward direction, as in those we have cited, it

affects the lateral extension of the middle and lower skin on the faces

of these animals, as well as the grinning contortion of the corner of

the mouth. It may also have to do with the grumbling sound issuing from

the throat-pouch, which is uttered by the animal when agitated, as he

rapidly opens and closes his mouth.

The strong sterno-cleido-mastoid muscle found in these animals, and

especially in the orang and gibbon, can be divided without difficulty

into a sternal and clavicular portion. The two portions diverge from

each other in a downward direction. As Bischoff justly states, a

muscle not hitherto observed in man may be traced in all four species

of anthropoids, a muscle which extends from the external part of the

clavicle to the transverse process of the first cervical vertebra.

Bischoff has called it the musculus omocervicalis. It is found in other

apes, although the site of its origin varies, sometimes occurring on

the spine of the scapula. Our Munich anatomist differs from Huxley in

regarding this muscle as “a brilliant proof of the relation of all apes

with each other.” I give this assertion without further comment.

The muscles which extend between the head, sternum, and clavicle,

together with the muscles of the acromion process of the scapula, make

an external covering to the throat-pouch, which I shall describe

presently. The pectoralis major of the gorilla, as well as that of man,

divides into two portions, one attached to the clavicle, the other

to the cartilages of the true ribs. The former is divided from the

deltoid by a wide interval, filled with connective tissue and fat. But

both portions of the pectoralis major are divided by a tolerably wide

space, into which, in Bischoff’s opinion, the throat-pouch is inserted.

This, however, I do not believe, since that organ would be compressed

and strangulated between the two portions of muscle whenever they were

exercised. It may, however, be supposed that room for an enlargement

of the throat-pouch when the animal is bellowing is afforded by the

existence of these spaces. Bischoff is right in the assertion that

the clavicular portion of the pectoralis major is wanting in the

orang-utan. The upper part of this muscle springs directly from the

sternum. The lower sternal ribs give origin to the pectoralis minor.

The chimpanzee and gibbon display clearly in this muscle the separation

we have mentioned into a clavicular and a sternal portion.

The structure of the pectoralis minor in these apes is full of

interest. In the gorilla it divides into an upper portion of firmer

tissue, less easily separable into digitations, which arises from the

third to the fifth ribs, and a lower portion, separable into three

digitations, of which the upper segment laps considerably over the

lower segment of the upper portion. In the chimpanzee an upper portion

of less firm texture extends from the second to the fourth, and a

lower with three digitations from the fourth to the seventh ribs. This

second lower portion is sometimes absent. I have seen the upper portion

attached to the coracoid process of the scapula, and the lower portion

to the ridge of the greater tuberosity of the humerus. In the orang

an upper portion, separable into three digitations, extends from the

second to the fifth ribs, and is attached to the coracoid process. A

lower portion, also separable into three digitations, extends from the

fifth to the seventh ribs, and is also attached either to the greater

tuberosity of the humerus or to its edge; this latter portion projects

below over the pectoralis major. In the gibbon (_Hylobates albimanus_),

the upper portion starts from the second, the lower from the third to

the fifth ribs. It may here be remarked that the pectoralis minor is in

man also sometimes separable into digitations, which may be connected

both with the coracoid process and with the capsular ligament of the

shoulder-joint. In anthropoids the tendon of insertion of this muscle

is remarkably slender.

According to Duvernoy, in the gorilla a fibrous, hood-like fascia

covers the whole region of the occiput and neck. In adult males

this fascia is 20 mm. in thickness. In a female dissected by me

the rudiments of a similar hood-like cervical fascia were present.

Duvernoy is justified in supposing that this is not yet developed in

the young gorilla, and that a layer of connective tissue and fat is

substituted for it. In a young gorilla I saw the trapezius divided

into distinct bundles of flesh by layers of fat (Fig. 50, ~15~). The

fascia corresponds to the great development of the trapezius, and the

same characteristic development exists in other anthropoids. The adult

male gorilla displays a powerful _ligamentum nuchæ_ in connection

with the long spinous processes of the cervical vertebræ, as well as

powerful inter-spinales muscles, spinales colli, and semi-spinales

colli and dorsi. The great development of the spinous processes of

the dorsal vertebræ of gorillas (Fig. 17), and also chimpanzees and

orangs, involve the development of powerful semi-spinales, as well

as of strong, fourfold spinales and inter-spinales muscles. The

whole of the fleshy formation of the neck of an adult male gorilla

which is covered by the trapezius is very voluminous, and especially

the splenius capitis and colli, the long cervical muscle (_Musculus

longissimus cervicis_), and the long head-muscle (_Musculus longissimus

capitis_), which have also been regarded by me as parts of the long

spinal extensor, and finally the oblique and vertical muscles at the

back of the head. With Chappuy, I am disposed to regard the latter as

modifications of the spinales and inter-spinales.

The levator anguli scapulæ is divided in anthropoids as in man. The

subclavius is slender, except in the gorilla, and in the latter animal

it sends a tendon obliquely to the coracoid process.

In all anthropoids the deltoid is strongly developed. In the gorilla

it projects forwards and outwards in order to attach itself to the

humerus, almost in its centre. Here it is separated from the brachialis

anticus in a manner with which we are only imperfectly acquainted. It

extends nearly as far in the gibbon and orang, while in the chimpanzee

its attachment is higher up. Bischoff observes, and it was previously

suggested by Vrolik, that in the chimpanzee the coraco-brachialis

muscle possesses at its origin a moderately large second portion, which

tends downwards over the lesser tuberosity of the humerus, and adheres

to its edge. But I have seen both portions of the muscle in question

attached to the coracoid process of the scapula in apes of this

species. In the gorilla, orang, and gibbon the position of this muscle

corresponds to that in man.

Chapman and Bischoff speak of a muscle common to all apes which starts

from the tendinous attachment of the _latissimus dorsi_ on the edge

of the lesser tuberosity of the humerus, and tends downwards on the

inner side of the humerus, and to this muscle they give the name

_latissimo-condyloideus_. Bischoff goes on to say that this muscle goes

in some cases into the fascia which covers the biceps; and in others,

as in the baboon, it is attached to the inner inter-muscular septum and

to the internal condyle of the humerus. In the gibbon it only extends

as far as the centre of the humerus, but in the orang it reaches to the

condyle, where it is pierced by the ulnar nerve. Bischoff adds that

this formation is wanting in man.

This structure is indeed remarkable in anthropoids. The muscle starts

in a lateral direction from the insertion point of the _latissimus

dorsi_. In the gorilla alone I observed that it started from the

coracoid process of the scapula, together with the two portions

of the pectoralis minor; it was connected for a space with the

coraco-brachialis, and finally it was attached, in the upper part of

the lower third of the humerus, to the inter-muscular septum which

is found between the brachialis anticus and the triceps. In the

chimpanzee, on the other hand, it has its origin in the _latissimus

dorsi_, and divides into an anterior and posterior portion; the former

is attached to the inner condyle of the humerus, while the latter is

connected either with the middle or inner head of the triceps. In the

orang the same division of this muscle may occur. In one of these

animals I observed an anterior portion, very thin and semi-membranous,

attached by an extremely slight tendon to the coracoid process of the

shoulder-blade, while the hind portion issued from the _latissimus

dorsi_. They were both in connection with the triceps and brachialis

anticus. In other instances the muscle consisted only of the posterior

portion, issuing from the _latissimus dorsi_. In the white-handed

gibbon, the muscle issued from the region in which the tendons of the

_latissimus dorsi_ and of the teres major are united, and was inserted

into the fascia which is found between the bicipital and the brachialis

anterior. This attachment may also occur in the centre of the shaft of

the humerus. Chapman and Chudzinsky have observed anomalous instances

of this formation in coloured races.[70]

It is well known that in man the biceps is inserted into the tuberosity

of the radius by means of a flattened round tendon. This tendon,

however, opposite the bend of the elbow, gives off a broad expansion,

which passes into the fascia of the forearm, and is termed _Aponeurosis

bicipitis_. In the gorilla this aponeurosis is carried on as strong

fibrous bundles of the fascia of the forearm into the palmar fascia. In

the gibbon the short head of the muscle does not always start from the

lesser tuberosity of the humerus, nor from the tendon of the pectoralis

major (Huxley), but sometimes from the edge of the lesser tuberosity,

which is here connected with the _latissimus dorsi_, as well as with

the sub-scapularis, the brachialis anticus, which is more to the side,

and with the triceps. In the gibbon, as Bischoff justly observes, the

supinator longus only reaches as far as the centre of the radius,

instead of extending to the styloid process of that bone, as it does in

other anthropoids, and in man.

The palmaris longus is wanting in the gorilla, but not in other

anthropoids. The long flexor muscles of the fingers and the lumbricales

resemble those of man (Figs. 51, 52). The flexor longus pollicis is

absent in the gorilla. Duvernoy considers that it is replaced by a

tendon of the long flexor of the fore-finger, but I have been unable

to verify the existence of this tendon. The same muscle is also absent

in the chimpanzee and the orang, but it may be traced in _Hylobates

albimanus_. Chapman states that in the gorilla the pronator radii teres

only sends forth one head,[71] but I have found it to be bicipital

in animals of this species. The lower or hinder head issues, as in

man, from the coronoid process of the ulna. Both in the gorilla and in

the chimpanzee it extends far in a downwards direction on the radius

(Fig. 52). The flexor carpi radialis starts in the chimpanzee with one

head from the inner condyle of the humerus, and with the other from

the radius. Bischoff describes the structure of the long abductor of

the thumb in the orang, the baboon, the _pithecia_, and the _hapale_

as resembling that of man. But in the gorilla, the chimpanzee, and

the macaca the tendon divides into two parts. Nor does one tendon

belong, as in man, to a short extensor of the thumb, but the latter is

wholly absent, and the division of the tendon only implies a continued

division of the attachment to the trapezium, as well as to the

metacarpal bones of the thumb. This division of the tendon also occurs

in the gorilla, which likewise possesses a short extensor of the thumb.

In this point, again, apes display a greater likeness to one another

than to man.

[Illustration:

Fig. 51.--Palmar muscles of man. _a_, Ligaments of wrist,

especially the anterior ligament. _c_, _c′_, Sheathing

ligaments. _d_, _e_, _f_, Oblique fibres of the ligaments

of the sheath of the flexor tendons. 1, 2, Tendons flexor

sublimis, and of the flexor profundus muscles of the fingers.

3, The reciprocal perforation of these tendons. 4, Continuation

of the tendons of the flexor profundus of the fingers. 5,

Tendon of the flexor longus pollicis. 6, Abductor pollicis. 7,

8, 9, Flexor brevis, adductor, and opponens pollicis. 10, 11,

12, Flexor brevis, abductor, and opponens minimi digiti. 13,

Lumbricales. 14, First dorsal inter-osseous muscle.

]

According to my own researches, the long abductor of the thumb in

anthropoids forms a muscle not more considerable than one in proximity

with it, of which the origin and more central direction recall the

short extensor of the human thumb. In all four species I found that

the abductor had two tendons, and was attached to the trapezium.

The muscle in its vicinity is inserted above the base of the first

metacarpal bone. I have not been able to discover an extra extensor of

the thumb in the gorilla. The question now arises what we should think

of the second muscle, which is found in these animals in the vicinity

of the abductor. In my opinion, it may be confidently accepted as a

short extensor of the thumb, since it always effects an extension of

the metacarpal bone of that member, and in this act of extension it

is supported by the long extensor which acts upon the phalanges. It

must be remembered that the comparatively short thumbs of anthropoids

have not to be employed in so many different ways as the human thumb,

and that we cannot therefore be surprised that the development of the

short extensor is less complete. A special extensor muscle of the index

finger is either altogether absent in the gorilla or very slightly

developed, while it is very apparent in _Hylobates albimanus_ (~6~,

Fig. 53). In the chimpanzee this muscle sends a tendon to the middle

finger. In the orang there is one extensor common to the four fingers.

In the gibbon’s hand, this, as well as the other extensor and flexor

muscles, is remarkable for its excessive slenderness. The manifold

connections of the extensor tendons with each other are an interesting

peculiarity (Fig. 53).

[Illustration:

Fig. 52.--Palmar muscles of gorilla. _a_, Anterior ligament.

_b_, Remains of the skin of palm, here covered with a very

sinewy skin. _c_, _f_, Oblique fibres of the ligaments of the

sheath of the flexor tendons of fingers. 1, 2, Flexor tendons.

3, Spaces between the heads of the flexor brevis pollicis,

whence in man the tendon of the flexor longus pollicis issues

(comp. Fig. 51, ~5~). 4, 3, 3′, 5, Abductor, flexor brevis,

abductor pollicis. 6, 7, 8, Opponens, flexor brevis, abductor,

minimi digiti. 9, Dumbricales. 10, Supinator longus. 12, Flexor

sublimis digitorum. 13, Flexor minimi digiti. 14, Flexor carpi

ulnaris.

]

In the chimpanzee I observed a superficial flexor, common to the

fingers, and enlarged in the region of the third and little fingers.

A superficial flexor, belonging to the index finger, started from the

inner condyle of the humerus, and from the back of the inter-muscular

septum. The deep finger-flexor was attached to the four fingers. In

the orang the first of these flexors forms a two-tendoned belly for

the index finger, as well as one for the other three fingers. The deep

flexor only displayed two bellies. In the gibbon, on the other hand,

the superficial flexor displays four bellies.

[Illustration:

Fig. 53.--Muscular system of the back of a gibbon’s hand. 1, The

extensor carpi radialis longior and brevior. 2, Abductor longus

pollicis. 3, Extensor primi internodii pollicis. 4, Extensor

secundi internodii pollicis. 5, Extensor communis digitorum. 6,

Extensor indicis. 7, Extensor minimi digiti. 8, Extensor carpi

ulnaris. 9, First dorsal inter-osseous muscle. 10, Continuation

of the same to index finger. 11, 12, The other inter-osseous

muscles of this region. A, The posterior annular ligament.

]

In the carpus of the chimpanzee there is, so far at least as my

experience goes, a so-called sesamoid bone. It is in this instance in

connection with the scaphoid and trapezium bones, just where the fibres

of the anterior and posterior ligaments of the wrist pass into each

other. In the chimpanzee the tendon of the long abductor muscle of the

thumb sends some fibres into this sesamoid bone, while the other fibres

of the tendon of this muscle, which divides into several strips, are

inserted in the trapezium bone, and a few also in the base of the first

metacarpal bone.

The short flexor muscle of the thumb, of which Bischoff has denied the

existence, is certainly present in these animals. In the chimpanzee

the lower fibres of the short abductor muscle of the thumb have their

origin in the sesamoid bone. The middle fibres, of the same muscle

issue from the strips of ligament attached to the sesamoid bone. On the

other hand, the upper part of the muscle has its origin in the anterior

annular ligament. In the orang, the lower fibres of the short abductor

of the thumb likewise have their origin in the sesamoid bone, while

the central fibres again start from the anterior annular ligament.

The upper fibres are strong, and are inserted into the base of the

first metacarpal bone. In a dissection of the orang the flexor longus

pollicis sent a thin, tendinous expansion on to the bone. This sesamoid

bone is also found in the gorilla, although Duvernoy and Rosenberg do

not appear to be aware of its existence.[72]

In the palm of the gorilla’s hand there is a short abductor, a short

bicipital flexor, an opponens, and an abductor of the thumb. The

longer belly of the short flexor extending in a more radial direction,

and in connection with the opponens, is only slightly developed. In

the muscular system of a gorilla’s little finger we may observe an

abductor, a short flexor, and an opponens. The palm of the chimpanzee

displays a short abductor, an opponens, a short bicipital flexor,

and an adductor of the thumb; also an abductor, a short flexor, and

an opponens of the little finger. In the orang I observed a short

abductor, a short flexor with two bellies, an opponens, and an adductor

of the thumb. In addition to the short flexor of the thumb, Langer and

Bischoff describe another short, independent muscle, representing the

long flexor, and attached to the second phalanx, but I have not myself

ascertained the existence of this muscle. The same anatomists mention

an adductor between the third metacarpal bone and the first joint of

the thumb, and another between the second metacarpal bone and the

second joint of the thumb, passing on into the extensor tendon. I am

myself convinced of the existence of a twofold adductor, but not of the

fact that the tendon of one of the muscles (termed by Langer the second

opponens) passes on into the extensor tendon. In the little finger of

the orang there is an abductor, a short flexor, and an opponens. In

the gibbon there is a short abductor, a faintly indicated opponens, a

short bicipital flexor, and an adductor of the thumb. In _Hylobates

albimanus_ this adductor divides into four or five portions, which

are attached to the whole of the first metacarpal bone. In the little

finger there is an abductor, a short flexor, and an opponens. In the

same animal the first inter-osseous muscle is attached by one portion

to the second metacarpal bone, by the other to the base of the second

phalanx of the index finger (Fig. 53, ~9~, ~10~).

Bischoff has described the muscles which Halford terms _Contrahentes

digitorum_ (contractors of the digits), which lie deep in the palm of

the hands and feet of the chimpanzee and gibbon, the mandril, baboon,

and other apes.[73] They rest upon the inter-osseous muscles, and are

covered by the tendons of the long flexors of the digits, as well as

by the lumbricales muscles. I have been unable to trace these _Musculi

contrahentes_ in the gorilla. In a female chimpanzee I observed a

_Musculus contrahens_ for the fourth, and another for the fifth finger,

and the same for the fourth and fifth toes. In the orang I observed a

_Musculus contrahens_ for the fourth, and one for the fifth fingers,

and two faintly indicated _Contrahentes_ for the fourth and fifth toes.

Similar muscles of the second, fourth, and fifth fingers, and of the

fourth and fifth toes, may be observed in the white-handed gibbon.

In correspondence with the height of the pelvic bones, the gluteus

maximus of these animals only displays a moderate width in comparison

with its length. The tendon which attaches it to the femur extends

low down, almost as far as the knee-joint. The gluteus medius and

minimus are also long, in correspondence with this structure of the

pelvis, although they are attached to the large trochanter, and to

the posterior inter-trochanteric line. The climbing muscle (_Musculus

scansorius_), which extends between the hip-bone and the condyles of

the femur, was discovered by Troill in the chimpanzee, and by Bischoff

in the orang, and is described by them as strongly made; it appears

to be absent in the gorilla and the gibbon. The pyriformis generally

forms portions of the neighbouring muscles. The tensor vaginæ femoris,

which is strong and wide in most anthropoids, is either greatly reduced

or altogether absent in the orang. The sartorius is not, as in man,

attached to the inner surface of the tibia, just below the internal

tuberosity, but it is inserted much lower down on this surface. In

the gorilla it has a tricipital attachment, one to the deep fascia of

the thigh, and two others to the internal border of the tibia. In the

chimpanzee and the gibbon the muscle extends equally low down. In the

orang it does not go so far, but the _gracilis_ and _semi-tendinosus_

are in the same relative position. The biceps of the femur is very

apparent in the orang; its long head divides in two parts, of which the

lower is inserted in the fibula, and is here united with the short head.

Bischoff at first denied the existence of the plantaris in the

chimpanzee, and Brühl had previously done the same, but it is as

normally present in that animal as in man, in whom also it is sometimes

absent. I, however, as well as other observers, have failed to discover

it in the gorilla, orang, and gibbon. The popliteus is developed in

every instance. The tibio-fibular muscle (_Musculus peroneotibialis_),

covered by the popliteus, of which the existence was ascertained by

Gruber, has not been observed by me in any of the anthropoids, with the

exception of the chimpanzee. But it was very apparent in a red sea-cat

monkey (_Cercopithecus ruber_).

The gastrocnemius, which is easily separable into two heads, and the

peroneal muscles have not the same relative width in anthropoids and

man, since in the former case the calf of the lower limb is small, and

it lacks the pleasing roundness which characterizes this part of the

human structure. These muscles, especially in the orang and gibbon,

appear to take a lateral direction. The Tendo Achillis is present,

but it has not the prominent development in height and width which

we observe in man. The long extensor, flexor, and tibial muscles are

in all cases fully developed. The peroneus tertius, as it is termed,

although it should only be regarded as a part of the extensor longus

digitorum, is absent in anthropoids.[74] I myself am not disposed, with

Huxley, Bischoff, and others, to regard this muscle as an abductor.

Brühl perceived in a chimpanzee a fourth rudimentary peroneal muscle

(_Musculus peroneus intermedius_), extending between the peroneus and

the little toe, a muscle sometimes found in man, and which I have

myself only observed in one adult chimpanzee. In the gorilla and the

chimpanzee the extensor longus digitorum passes through a remarkably

strong transverse ligament, formed of fibrous cartilage, which covers

the tarsus. It acts upon the four outer toes (Fig. 55). Brühl has

described the characteristic contraction and extension of the tendons

of the long and short extensors of the toes in the chimpanzee, but I

have myself found some difficulty in producing this action. In Fig. 55

I have endeavoured to represent this condition in the most natural way.

The extensor proprius pollicis is in all cases developed. The extensor

brevis digitorum produces a large, oblique belly for the great toe

(Fig. 55). In the gorilla there is for the great toe an abductor, a

bicipital flexor, an adductor, and an opponens (comp. Fig. 54).

From the extensor brevis digitorum the belly for the great toe rises

with a certain independence. On the right foot of a chimpanzee I

observed a fifth belly of this muscle, going to the little toe (Fig.

55). As my illustration is taken from this specimen, I have represented

the foot with, or in spite of, this interesting anomaly, which, as we

know, sometimes occurs in man.

[Illustration:

Fig. 54.--Muscular system of the human foot. 1, Tibialis anticus

and extensor proprius pollicis. 2, Extensor longus digitorum.

3, Tendon of peroneus tertius. 4, 5, Peroneus longus and

peroneus brevis. 4′, 5′, Tendons of the same. 6, 7, Tendons of

the extensor longus and extensor brevis digitorum.

]

The flexor brevis digitorum displays perforated tendons, belonging

to the second and third toes. The flexor longus digitorum displays

perforated tendons for the fourth and fifth toes. The flexor longus

pollicis divides into two tendons, one of which goes into the toe

itself, while the other is connected with the flexor longus digitorum,

and displays perforated tendons for the third and fourth toes, while

the perforated tendons of the second and fifth toes have their origin

in the other flexor.

[Illustration:

Fig. 55.--Muscles on the upper side of chimpanzee’s foot. 1.

Tibialis anticus muscle. 2, Extensor proprius pollicis. 3,

Extensor communis digitorum. 4, 5, Peroneus brevis and peroneus

longus. 6, Tendon Achilles. 7, Extensor brevis digitorum. 8,

Slip of the same for great toe. 9, First dorsal inter-osseous

muscle. 10, Adductor pollicis. 11, Abductor minimi digiti.

]

In the gorilla the lumbricales muscles of the foot are powerful. The

first inter-osseous muscle is likewise well developed and bicipital.

There is a short flexor and an abductor for the little toe. I have not

yet been able to assure myself of the existence of an opponens for that

toe. In the chimpanzee the muscular system of the great and little

toe does not essentially differ from that which we have described in

the gorilla. The flexor brevis digitorum forms the perforated tendons

of the second and third toes. The flexor longus digitorum provides

the fourth and fifth toes with perforated, and the second and fifth

toes with perforating, tendons, while those which belong to the third

and fourth toes have their origin in the flexor longus pollicis. As

in the gorilla, the latter muscle produces a fibrous investment for

the tendons of the flexor longus digitorum. In the orang there is an

abductor of the great toe, a very slightly developed opponens, a short

bicipital flexor, and an adductor. One of the long flexors of the toes

appears to represent the flexor longus pollicis in man. It provides

the second and fifth toes with perforating tendons, while those of the

third and fourth toes have their origin in the other flexor longus

digitorum. There is no long flexor tendon on the great toe. The

perforated tendons in this case generally belong to the short flexor

muscle. In addition to the perforated tendons of the fourth toe, there

is the long flexor already described.

In a gibbon’s great toe I observed an abductor, a short bicipital

flexor, and a slightly developed opponens, to which a wide fan-shaped

adductor is attached. The first dorsal inter-osseous muscle is, as in

the same animal’s hand (Fig. 53), attached to the first phalanx of the

second toe. The flexor longus digitorum provides the third and fourth

toes with perforating tendons, and also gives off a tendon for the

great toe. On the little toe there is a remarkably slender perforating

tendon. While the first of the two long flexors represents the human

flexor longus pollicis, the flexor longus digitorum is in this instance

limited to the little toe. In the gibbon, as well as in the orang, the

gorilla, and the chimpanzee, the two muscles are connected together

by an aponeurosis. It may be here mentioned that in the human foot

the flexor longus pollicis occasionally gives off a flexor for the

second and even for the third toes. In the gibbon, as Bischoff justly

observes, a muscle covers the flexor longus digitorum, which is still

undivided, but already enlarged. From this muscle perforated tendons

issue for the third and fourth toes. The second toe is provided with

such a tendon from the flexor brevis digitorum. The muscle we have

mentioned seems to represent the Quadratus plantæ, which is often

developed in the other anthropoids, although only to a slight extent.

With respect to the muscles of the small toe of the orang and gibbon,

I need only say that in the latter species the opponens seems to be

absent (Fig. 55).

It will be seen from the foregoing account that, in spite of several

apparently important peculiarities, in spite of great and manifold

variations which are established, even although our authorities do

not always agree together, the muscular system of anthropoids is on

the whole very like that of man. It displays, especially in the lower

limbs, peculiarities of structure which render them capable of walking

in an upright position, and others again which they have in common with

the lower animals, but on the whole the anthropoid characteristics of

the muscular system of these animals are predominant.

The digestive system of anthropoids likewise affords interesting points

of comparison. The cavity of the mouth is, as we have seen, bordered

by large and flexible lips. The mucous membrane of the mouth and the

gums are flesh-coloured; they assume a darker colour in older animals,

and are then sometimes marked with spots of a bluish or brownish grey.

Ehlers describes, as a peculiarity in the mucous membrane of the mouths

of the gorilla and chimpanzee, that there are what he calls buccal

folds, which pass on both sides from the fore surface of the upper and

lower jaw into the mucous membrane of the cheeks, and are of the height

of the canine teeth.[75] I have myself only observed these folds in the

gorilla, of which an illustration is given in Fig. 3, and not in any

other specimen. I have observed scarcely any indications of these folds

in other anthropoids, and then only of such a doubtful nature that I am

not disposed to regard the circumstance as of any special significance.

A small band on the upper and lower lips, sometimes only slightly

developed, but always perceptible, is present in all anthropoids.

The tongue is small, and not provided at its base with several

great concave follicles as in man; these are at least only faintly

represented, and not easy to observe. Around them there rise pock-like,

tufted warts, very close together, which in an aged gorilla are apt to

become hard and horny. These are also prominent between the follicles

of the tonsils. The circumvallate papillæ of the tongue are less

numerous than in man, and often, especially in the chimpanzee, they

take the form of a cross, or of the letter T, or in the gorilla of a V.

The uvula and palate present no special variation from the human

type. On the hard palate there are a number of folds, or rather

swellings, which extend laterally from the central suture of the

palate, towards the row of teeth in the upper jaw; these are sometimes

simple, sometimes complex, and vary in their details in individual

cases. They are particularly marked in the adult chimpanzee, and

are also very apparent in the gibbon, and they are arranged with a

somewhat ornamental regularity. These inequalities are not altogether

insignificant in the human palate, but this subject has not been much

studied since Gegenbaur directed the attention of scientific men to

them, and special light has been thrown upon it by Bischoff and Ehlers,

as far as anthropoids are concerned.

The teeth afford us important material for comparison. In the case of

anthropoids the formula for the teeth of the slender-nosed or Old-World

apes (_Catarrhina_) will generally apply: _i_ 2/2 _c_ 1/1 _p_ 2/2 _m_

3/3. The following is the formula for the milk-teeth: _i_ 2/2 _c_ 1/1

_m_ 2/2. Magitot and Giglioli[76] have shown that the milk-teeth are

cut in the same order as those of man--first, the lower; second, the

upper incisor teeth; third, the front pre-molars; fourth, the back

pre-molars; fifth, the canine teeth. According to the same authors, the

permanent teeth are cut in the following order:--first, the first molar

teeth; second, the lower, and then the upper incisor teeth; third, the

pre-molars; fourth, the canine teeth; fifth, the second molar teeth;

sixth, the third molar teeth. In the skull of a male gorilla, Giglioli

found that the permanent canine teeth were cut almost simultaneously

with the third molar teeth, and after the appearance of the second

molar teeth. The cutting of the canine teeth appears to be a longer

process than that of the other teeth.

In anthropoids the structure of the permanent teeth varies with the

species, and even with the sex. In the gorilla the two upper central

incisor teeth are wide, chisel-shaped, and much larger than the pair of

lateral incisors. The four lower incisor teeth are of about the size

of the upper lateral incisors, and, like these, are chisel-shaped, but

not so wide. The powerful upper canine teeth of an aged male are curved

in their lower part, both outwards and inwards. Their form is that of

a three-sided, cuneiform pyramid. The anterior surface is rounded, and

near its inner edge a deep furrow may be observed, extending from the

neck of the tooth almost to its point. The outer and inner sides of

the tooth meet in a sharp angle, somewhat convex in front, and level

or slightly concave behind. The inner side is concave, and furnished,

nearly in the centre, with a deep longitudinal farrow. The lower canine

teeth of an aged male are shorter than the upper, curved on their

upper and outer surface, and somewhat behind. Their form is also that

of a three-sided pyramid, rounded in front. The longitudinal furrow

which traverses their inner segment is much shorter than that on the

upper tooth. The outer side is somewhat convex, and at the same time

somewhat retreating, and is provided on its posterior segment with

two longitudinal furrows, or more rarely with one, reaching from the

neck to about the centre of the tooth. The inner side, like that of

the upper teeth, is somewhat concave. The lower canine teeth project

like pillars over the upper ones (Figs. 15, 16). The canine teeth of

a young male gorilla are less sharp in their angles, although they

already present the form of a three-sided pyramid. The canine teeth of

the adult female gorilla are much smaller than those of the adult male,

and are laterally more compressed. The three-sided pyramidal form is

only slightly marked. The outer surface is convex and furnished with

a scarcely apparent central longitudinal ridge. On the inner surface,

or that which is turned to the cavity of the mouth, there are from two

to three longitudinal furrows reaching from the neck to the centre

of the tooth. The lower teeth are of a three-sided, pyramidal form,

presenting an interior, posterior, and inner superficies.

The pre-molars of an aged male gorilla are wide, and are furnished

with a large outer, and a smaller inner, cusp. The three four-cusped

upper molars display a more regular and symmetrical arrangement of

their cusps than is the case with the female, in which the position of

the cusps is rather variable. Except for the difference of size, the

relative conditions of these teeth are the same in male and female.

The first pointed lower pre-molars are in the male of the form of a

four-sided pyramid, convex on the anterior and outer surface, flat on

the side directed to the cavity of the mouth, and marked with furrows

on the posterior surface. The small second and lower pre-molars have

two anterior and one posterior cusp. The last is generally worn away

at an early age. Each molar tooth has two outer and two inner cusps,

opposite to each other, and one posterior cusp. We cannot here fail to

notice the likeness to the conditions of the human teeth, a likeness

which is still more striking in the female.

In the chimpanzee, also, the upper central incisor teeth are broadly

chisel-shaped, while the upper and lower lateral incisors are

smaller. In the male there is often a considerable gap between these

and the canine teeth. The latter present the form of a three-sided

pyramid, of which the anterior edge is blunt and tends outwards,

while the posterior angle is sharp, scooped out in its upper third,

and terminating at the base of the crown in a posterior cusp. The

pre-molars have an external and an inner cusp; the molars have two

external and two inner cusps, connected with each other by their

enamel. The lower canine teeth of these animals are likewise of

the shape of a three-sided pyramid, of which the anterior angle is

very blunt, while the inner and posterior angles are sharply cut.

The anterior surface is not grooved like the upper canine teeth.

The lateral angle is much rounded. The back teeth plainly display

the posterior fifth cusp, which may also be observed in man. In the

orang-utan the characteristics of the upper incisors are such as we

have described in the case of other anthropoids. The upper canine

teeth are shaped like a three-sided pyramid, and are furnished with a

longitudinal furrow on the anterior side. A similar furrow is found on

the posterior superficies of the lower canine teeth. The back teeth

display no special characteristics when compared with those of other

anthropoids.

The canine teeth of these anthropoids are much worn down by age

on their posterior surface. Deep transverse grooves of varying

size characterize the teeth of anthropoids, owing to the unequal

distribution of the coating of enamel. These are developed with their

advancing growth. In addition to these incised furrows, longitudinal

marks, with raised edges, also appear, and especially on the anterior

surface of the incisor teeth.

In the gibbon the anterior surface of the incisor teeth is smooth; in

this animal the upper central incisor teeth are the largest, while the

lower central incisors are the smallest. The long and strong upper

canine teeth, which are laterally compressed, display a sharp posterior

angle, and an anterior and inner longitudinal furrow.

It has sometimes been said that the grooves found on the external

contour of the back teeth of anthropoids, extending to their roots,

constitute a not unimportant distinction between their structure and

that of the human teeth, in which the grooves do not extend to the

roots. But the corresponding human teeth do sometimes exhibit very

deep and extensive furrows. I cannot, therefore, ascribe any peculiar

significance to this assumed distinction. The development of the canine

teeth, like those of beasts of prey, seems to me much more important. A

supernumerary back tooth may sometimes be observed both in man and in

anthropoids, including also the gibbon.[77]

The stomach and intestines of these animals present only a few striking

differences from the same organs in man. The length of the intestines

varies in man as well as in anthropoids. I have only observed the

_valvulæ conniventes_ to be somewhat clearly developed in the gorilla

and the orang. The cæcum of these apes is long, broad, placed with the

power of free movement in the peritoneum, and furnished, especially in

the case of the orang, with a large, very long, and spirally coiled

vermiform appendix.

The liver is divided into two principal lobes, but in the orang

this division is not very clearly marked. I have not myself observed

a subdivision of these lobes, occurring on their edges, which is

mentioned by Bolau and Auzoux in the case of the gorilla. Bischoff

notices in the gorilla the absence of the H-shaped arrangement of the

fissures on the under surface of the liver, so noticeable in man; and

the same remark applies to other species of anthropoids. Moreover, the

fissures on this part of the liver are not incised on the substance

with the same uniform depth. The gall-bladder of the gorilla and the

orang is not remarkable for its size; in the chimpanzee I found that

this organ is large and twisted, and it is also large in the gibbon.

The spleen is elongated in the gorilla, chimpanzee, and gibbon, shorter

and wider in the orang. On its left contour it is uniformly bevelled

off. There is nothing in the pancreas which calls for remark.

The larynx of anthropoids possesses on the whole a structure resembling

that of man. This is especially the case at the entrance to that organ.

The anterior and specially vocal portion of the glottis is short, about

as long as the respiratory portion. In the chimpanzee there is a deep

cavity in the body of the hyoid bone. In the gorilla, chimpanzee, and

orang the throat-pouches or air-sacs correspond to Morgagni’s sacs.

These are the thin-skinned elastic sacs, closely united with their

surroundings by connective tissue. The right laryngeal sac appears

to be of larger diameter than the left. According to Duvernoy’s and

Ehlers’ accurate account only the upper portion of this organ occurs

in the gorilla. In that animal, and in the orang, a lower projection is

displayed, extending behind the sterno-mastoid as far as the shoulder,

and another extending to the pectoralis major muscle. In the chimpanzee

only the posterior segment is developed. It has been asserted that

in several cases there is found a single, irregular laryngeal sac,

communicating with the two Morgagni sacs, but I agree with Ehlers in

thinking this improbable. In such instances it seems likely that, owing

to the great want of symmetry in this organ, one of the sacs has been

overlooked. In an aged orang the throat-pouches, fastened together by

connective tissue, and covered by the external skin of the throat,

hang down slackly and heavily over the middle of the breast (see Fig.

9). According to Sandifort, the siamang is the only one of the gibbons

which displays a single throat-pouch; while Broca asserts that it

has two detached sacs, placed close to the larynx.[78] The halves of

the thyroid cartilage are generally connected with each other by an

intermediate piece.

The trachea of anthropoids generally includes from sixteen to eighteen

cartilaginous rings, but in the siamang there are twenty-one. They

ramify into branches which are, as a rule, wider on the right than on

the left side.[79] There is a further lateral ramification on the

right side, situated above the artery. Huxley and Ehlers hold that the

lungs of a gorilla are cleft like those of the human organism, the

right divided into three, and the left into two lobes. I have myself

observed this type, and in one instance I found three lobes on the

left. In the chimpanzee I saw that the right lung was divided into

three, and the left into two lobes. Bischoff observed an instance of

a chimpanzee which had four lobes on the right and two on the left

side. In an orang dissected by me I found only one lobe on each side,

with thin, slightly indented notches on the anterior edges of the

right lobe, and two on the left, and there was at the same time a

strongly marked indentation between the lobes. The lungs of a gibbon

are described as having four lobes on the right, and only one or two

on the left. I myself have examined a gibbon in which there were three

lobes on the right, and two on the left. It appears that there are not

unimportant individual variations of this structure in every species of

anthropoids; and indeed, human lungs are by no means exempt from them.

The male sexual organs correspond on the whole with the form and

arrangement of these organs in man. I must not omit to mention that the

penis of the swine-snouted baboon, and of other dog-headed apes, is

much more like the penis in man than is the case with anthropoids, with

the exception of the gorilla. In the last-named animal the scrotum is

short and tightly stretched. The right testicle is a little higher than

the left, and is divided from it by a wide raphé. The internal female

organs are also like those of the human organism, with only slight

variations. Bischoff is correct in the assertion that the external lips

of the pudendum and the mons veneris are almost wholly absent. Bolau,

Ehlers, and Hermes have ascertained that there is a menstruation which

occurs periodically, at any rate in the case of the chimpanzee, and the

other species cannot be exempt from the process. At such times there

is a blush and enlargement of the external parts, and a profusion of

the external lips of the pudendum, which are at other times scarcely

apparent. The nymphæ and the clitoris are of considerable size and

importance. There is often an excessive enlargement and reddening

of these parts, as well as of the posterior callosities in the

chimpanzee, and also in the baboon and macaca, during the period of

sexual excitement.

[Illustration:

Fig. 56.--The brain of an orang, seen from the side (Vogt, from

Gratiolet). F, Frontal lobe. P, Parietal lobe. O, Occipital

lobe. R, Fissure of Rolando. S, Fissure of Sylvius. C,

Cerebellum.

]

_Nervous system._--In this part of the organism we are especially

interested in the structure of the brain. Bastian justly remarks,

with reference to the brain of apes, that this family possesses many

cerebral characteristics in common, by which their close connection

with each other may be verified. Distinct stages of development have

been observed, which, however, cannot be classified in a consecutive

series. Starting from the brains of lemurs, which do not greatly

differ from those of rodents, we can advance by means of very distinct

transition forms to the more highly developed cerebral hemispheres

of the large anthropoid apes, the chimpanzee, the gorilla, and

orang-utan.[80]

[Illustration:

Fig. 57.--Brain of the chimpanzee, seen from above. The upper

part of the right hemisphere is removed so as to lay bare

the lateral ventricle (Vogt, from Marshall). L, Longitudinal

fissure (other indications the same as in Fig. 56). _c s_, The

corpus striatum in anterior cornu of the ventricle. _c a_,

Hippocampus major in descending cornu. _h m_, Hippocampus minor

in posterior cornu.

]

Very opposite views prevail among anatomists with regard to the

question which species of anthropoids possesses the most highly

developed brain. Some regard the chimpanzee’s brain as the simplest,

and that of the orang as the most highly developed. In all these apes

the lateral halves of the cerebrum, always divided from each other

by a deep longitudinal fissure, overlap the cerebellum as far as a

minute posterior segment. In this respect I find the brain of the

gorilla a little behind the other anthropoids. Up to this time, I have

only observed the projection of the cerebellum through the cerebrum

in the case of an orang[81] (see also Fig. 56). Retzius asserts that

the cerebellum of Lapps is incompletely covered, while the covering

is generally complete in the case of Slav and Tartar races. In German

and Latin races the cerebrum overlaps the cerebellum. In Mongolian,

Indian, and Negro races the covering appears to be generally imperfect.

[Illustration:

Fig. 58.--Brain of gorilla, side view (from Bolau and Pansch).

I., Frontal lobe. II., Fissure of Rolando. III., Parietal lobe.

IV., Temporal lobe. C, Cerebellum. _f s_, Fissure of Sylvius.

_s c_, External fissure parieto-occipital.

]

While the ground form of the gorilla brain approximates to a long

oval, and in this respect resembles the human brain, the brain of

chimpanzees and orangs is of a round-oval form. This is especially the

case with the chimpanzee (Fig. 57). In my opinion, the gorilla brain

is distinguished from that of the chimpanzee, but not from that of the

orang, by its very complex convolutions (Fig. 56).

[Illustration:

Fig. 59.--Brain of orang, seen from above (Duncan, from a

specimen in the Museum of Royal College of Surgeons). F,

frontal lobe. O, Occipital lobe.

]

In the gorilla, chimpanzee, and orang, the island of Reil in

the fissure of Sylvius is generally--at least, according to my

experience--overlapped by the operculum, although there are instances

in which this is not the case. In these three anthropoids, as Bastian

justly observes, the fissure of Sylvius is much less horizontal than

in man, and occupies a position more like that which it takes in the

black sea-cat monkey, the wanderers, and other macacas. In the gorilla

its direction is more horizontal than in the two other species of

anthropoids. The central fissure, termed fissure of Rolando, is very

marked, especially in the chimpanzee (Fig. 57 R); but it may also be

easily traced in other species of anthropoids (Fig. 58, II., 56, R).

The so-called simian fissure between the parietal and occipital lobes

of the cerebrum (Meynart’s elongated external occipital fissure),

presented in Fig. 58 _s c_, is very marked in the chimpanzee (Fig. 57,

_d_). The frontal lobes of the gorilla brain are high, while those of

the chimpanzee are short and low. It is said that those of the orang,

which are high and short, terminate in a beak-shaped curvature, but

this is not invariably the case.

[Illustration:

Fig. 60.--Longitudinal section of a gorilla’s brain (Bola and

Pansch). _s.cm_, Colloso marginal fissure. _f, p_, Internal

parieto-occipital fissure. _f, c_, Calcarine fissure, the

posterior part of the hippocampal fissure.

]

In the anthropoids we have been considering, and also in several of

the lower species of apes, there are three other fissures of less

importance in addition to those we have mentioned, namely, the fissure

parallel to the fissure of Sylvius, and placed behind it, the _corpus

callosum_ fissure, placed immediately above the _corpus callosum_ on

the inner side of the hemisphere of the cerebrum, and the calcarine

fissure (_Fissura calcarina_) (Fig. 60). The latter ends near the point

of junction of the inner and lower surfaces of the posterior division

of the hemisphere. The upper temporal convolution, termed by several

anatomists _Gyrus supramarginalis_, is said by Gratiolet to be absent

in anthropoids; but Rolleston, Bastian, and myself have all found it

well developed[82] (Fig. 56, orang, and Fig. 58, gorilla).

Bischoff asserts that the third frontal convolution (Broca’s

convolution) is very slightly developed in the chimpanzee, orang,

and gibbon. “Its great development in men,” Gewährsmann writes,

“constitutes one of the most marked distinctions between the brains

of apes and of men.”[83] In most of the other species of apes this

convolution is altogether absent, but Pansch is justified in the

assertion that it is fully developed in anthropoids. I cannot wholly

agree with Pansch in his analysis; but I must accept his statement

on this point (see the orang, Fig. 59). Gratiolet remarks that the

so-called annectant gyri (_plis de passage_) which serve as a covering

or _operculum_ for the posterior lobes in apes, are only superficially

apparent in man. In the chimpanzee the upper of those convolutions

is absent, while it is large in the orang, and likewise large and

undulated in man. In the orang the second annectant gyrus is covered,

but this covering is absent in man.[84]

In considering the inner structure of the brain of these animals, we

are first struck by the shortness of the _corpus callosum_. The soft

and thick anterior commissure of the third cerebral ventricle and the

thin posterior commissure have also been justly noted. In the lateral

ventricles more of the characteristics described in the human brain are

absent. The four eminences resemble those of man; nor does the fourth

cerebral ventricle present any remarkable differences of form. Neither

does the base or lower surface of the brain display any important

deviation from the human type. The transverse section of the nerves at

their intersection appears to me, however, to be somewhat more oval

than is the case in man.

There has recently been an attempt to recognize a pithecoid character,

or atavism, in microcephalic men, the smallness of whose heads is

allied with a greater or less degree of idiocy. A pithecoid structure

of the brain has also been traced in several individuals who are not

microcephalous, but subject to pathological affections. We will first

consider those who belong to the latter category. Krause examined

the brain of an ape-like boy aged seven years and a half, which, as

the author remarks, approximated in structure to the pithecoid type,

although without displaying microcephalic characteristics. The two

cerebral hemispheres were wanting in symmetry; they diverged from each

other in the region where the parieto-occipital fissure occurs on the

left cerebral hemisphere, and they formed an edge which curved outward

and backward so that the cerebellum remained uncovered. On the lower

surface of the frontal lobes there was a strongly marked ethmoidal

prominence. Neither of the fissures of Sylvius were closed, the left

less so than the right; the operculum was only slightly developed;

and the island of Reil and its fissures were almost uncovered. This

formation is almost the same as that of the brain of anthropoids.

The two central fissures of Rolando were close together, or less

deeply impressed on the edge of the hemispheres than is normally the

case, and forming no joint angle. Large and deeply marked pre-central

fissures seemed to represent the central fissures. The intra-parietal

fissures, diverging outwardly further than in man, received the

parieto-occipital fissure, a structure in conformity with the typical

brain of apes. The transverse occipital fissure became in this case a

deep fissure like the simian fissure, crossing the occipital lobes,

and almost completely dividing them from the parietal lobes. The

so-called _Fissura calcarina_, to which we have referred above, had

its origin on the upper surface of the occipital lobe, then joined

the parieto-occipital fissure, and went directly into the hippocampal

fissure (_Fissura hippocampi_) on its right side. This abnormal

structure is also in conformity with the typical brain of apes. The

first occipital convolution is divided from the upper parietal lobes by

the parieto-occipital fissure. Gratiolet asserts that this formation

occurs in many species of apes. The upper temporal convolution was

remarkably reduced on both sides, possessing only an average width of 5

mm. This characteristic reminded Krause of the brain of the chimpanzee.

In that animal the upper temporal convolution is always reduced.

Krause therefore asks whether some human brains may not possess the

typical structure of apes without being microcephalic. The brain we

have described scarcely differed from the normal weight; it possessed

all the convolutions and fissures, and indeed, the convolutions

were perhaps more numerous than in the normal structure, yet it was

different in every respect, and approximated in its whole structure to

the simian rather than to the human type. Krause adds that if the brain

had been placed before him without any intimation of its origin, he

should have been quite justified in concluding that it belonged to an

anthropoid ape, which stood somewhat nearer to man than the chimpanzee.

It is an unquestionable fact that some human beings, whether children

or adults, who are endowed with a defective bodily structure, and who

are affected with more or less pronounced physical incapacity and

mental weakness, by their appearance, ungainly tricks, and helpless

and aimless motions, impress us in the most forcible way with their

resemblance to apes. Different degrees of idiocy affect individuals of

limited intellect, and remind us of an absolutely brutish condition.

Krause describes the “ape-like” boy of seven and a half years old,

whom he had examined, as cheerful and inclined to play and dance, but

as passionate when he was teased. The child was very supple, fond of

climbing, and with great strength in his arms and hands, of which

the latter had a horny appearance, reminding him of the hands of a

chimpanzee. He could sit on the ground with his legs wide apart. His

gait was uncertain, and he was apt to tumble, falling with his knees

bent forward and his legs doubled under him; he was fond of hopping,

and at such times looked still more like an ape. The great toes of

both feet were at an angle to the foot, and thus gave the impression

of a prehensile foot. At first Krause supposed that this deviation was

produced by the child’s endeavour to supply a broader basis of support

for his uncertain gait; but he subsequently changed his opinion, since

he did not find the same peculiarity in other children of diseased

brain, as, for instance, in those suffering from water on the brain.

The boy could say very little, only papa and mamma, and it was long

before he could pronounce these words in two syllables; for the most

part, he only uttered a sound resembling a grunt. He imitated the

barking of a dog, with the sound of rolling _r_’s. He often stamped

his feet and clapped his hands together, making a grunting noise as

Krause had observed in the case of gorillas and chimpanzees. The boy

was smaller than other children of his age, and had weak eyes; his head

was sore, and his forehead narrow. His imitative tendency was strongly

marked, and his whole nature and all his movements strikingly resembled

those of apes. He had been much neglected by his parents.[85]

When I was a student at Berlin I had the opportunity of observing

a similar being of twelve years old, in what was at that time the

Weinbergswege, near the Rosenthaler Gate. This was a boy with a large

head, a low retreating forehead, glazed eyes, a morose expression, a

thin neck, prominent belly, crooked legs, large hands and feet. The

boy was of a slouching appearance, and his gait was unsteady: saliva

often dribbled from his wide mouth; and as he walked he held on to the

furniture, walls, etc., and often he fell powerless on his side, and

so remained in a crouching position. It seemed to give him peculiar

pleasure to creep on his hands and knees, and at such times he would

stamp with the closed fingers of one or the other hand upon the

ground, as if in triumph. This habit, his gait, and the gurgling sound

which was all that the boy could utter, constituted the points of his

resemblance to apes. All the other conditions of life were those of a

being whose mental and physical growth was arrested, and who, although

not epileptic, was to a certain extent idiotic. I am ignorant what

afterwards became of him.

In the course of a discussion on the instance adduced by Krause,

Virchow asks whether the psychological conditions of such a brain

are indeed simian. He is convinced that whoever has studied the

microcephalic child Margaret Becker (of Bürgel, Hanau) will find that

psychologically she had nothing in common with an ape. In her case

all the positive faculties and qualities of the ape were wanting;

the simian psychology was altogether absent, and there was only the

psychology of an imperfectly developed and deficient young child. Every

characteristic was human. Virchoff had the child in his room for hours

together during a period of two months, and was constantly occupied

about her, without observing anything in her nature which reminded

him even remotely of the psychological conditions of apes. She was a

degraded specimen of humanity, differing in no respect from the human

type.[86]

I also examined Margaret Becker, as well as another microcephalic

girl, who was in the Berlin Asylum in the years 1868 and 1869. With

respect to the former and more animated being, I have nothing essential

to add to the information published by Virchow. Ida X----, the other

individual whom I examined at Berlin, was at the time of my researches

aged thirteen years and five months. Her figure was slightly made and

well proportioned, while her profile reminded me to a modified extent

of that of the microcephalic Aztec, and also of the heads represented

in ancient sculpture of Mayapan, Palenque, and Copan. I must not omit

to say that Ida had light blue eyes and fair, glossy hair. She was

altogether impassive; could only utter the syllables _da-da_; and

once betrayed a slight sign of displeasure when the cold metal of the

measuring-rod was placed against the inner side of her thigh, for the

sake of obtaining the dimensions of the different parts of her body.

Virchow’s information respecting Esther Jacobwitz, of Waschahel, is

also extremely interesting. She was a microcephalic girl of the age of

fourteen, and a Hungarian Jew by race.[87] Virchow remarks that, in

his opinion, all Esther’s most striking characteristics presented the

strongest contrast to those of apes, since only negative traits have

hitherto been established, while all which characterizes the positive

development of the psychical life of apes was absent in this case. The

same remark applies to Ida X----. Virchow goes on to say that there

was undoubtedly something brute-like in the defects in question, but

that in order to reproduce the animal in its actual form and nature, so

as to show that the microcephalic child was really theromorphic, the

positive side of animal life must to some extent be presented to us,

and this was absolutely wanting.

Virchow also had the opportunity of examining a pair of twin children,

one of whom was quite normally developed, while the other (Karl

R----) was microcephalic. This was a very significant case, since two

individuals of the same birth were under consideration, so that the

question could be asked with greater confidence--Is this atavism, or a

morbid condition? From this point of view, it was of special interest

to establish the fact that the microcephalic child had, in fact,

displayed positive signs of a morbid condition.[88]

When I go through the accounts collected by C. Vogt of the lives

of well-known microcephalic beings,[89] I can find nothing which

specifically reminds me of the actions and habits of apes, although

we have an intimate acquaintance with their ways. These individuals

give the general impression of human beings whose bodily and mental

development has been arrested. According to Virchow’s experience,

all the cerebral disturbances are concentrated in the cerebrum in

these microcephalous cases. The anterior portions of the cerebrum are

affected to the greatest, and the posterior to the least, extent. Those

parts which are developed latest suffer the most, while those which are

the first to be developed generally escape disturbance.[90]

Klebs, Schaaffhausen, and others have sought to show that the mothers

of microcephalic children have suffered from severe pains of the uterus

during pregnancy. All scientific men consider that spasms of the uterus

distinctly affect the development of the brain of the offspring. Flesch

thinks it possible that these spasms of the uterus may have something

to do with the origin of microcephaly.[91] But he also asks whether

this morbid condition of the uterus may not have been produced by a

previously diseased condition of the offspring. This observer is,

moreover, still more inclined to make the influence of the father

responsible for the occurrence of microcephaly. In view of the fact

that there is much reason to suppose there has been a compression of

the uterus, and in default of any better suggestion, Flesch feels

justified in looking for a compression which has perhaps resulted

from some growth on the ovary. Hence ensues a disturbance, probably

inflammatory, of the organ of nutrition.[92]

Aeby also regards microcephaly, not as an expression of atavism, but

as the result of a morbid degeneration. “Microcephalic subjects do

not point back to the milestone which man left behind him in hoar

antiquity, and it is not through them that the chasm between man and

animals can be bridged over, nor even rendered less wide.”

Virchow’s researches led to the following conclusions, which we must

here subjoin:--1. There is no species of apes which presents that

precise configuration which is found in a microcephalic brain. 2.

Psychology offers the strongest arguments against men-apes. 3. The

instinctive side of psychical activity, which is almost wholly absent

in microcephalic subjects, is very prominent in anthropoids as well as

in other animals.[93]

In addition to these remarks, it may also be observed that among savage

races the medicine-men, shamans, sorcerers, rain-doctors, etc., often

assume ape-like attitudes in the contortions, leaps, dances, and other

gestures which are inseparable from their trade. Owing to their state

of excitement, in which they are not always mentally responsible for

their acts, this imitation may be often partly or wholly unconscious.

It is very common among the inspired Arabs termed Haschasch, who,

sometimes as dervishes, sometimes as poets or beast-tamers, roam

through the country and extend their wanderings from the interior

of Africa to the latticed gates of Dolma Bakhtsche. To them belong

also the dancing mendicant monks of Islam, who display their ape-like

gesture in the market-places and streets of Bokhara, as well as in the

other chief cities of Central Asia. In this case, indeed, many gestures

are conventional, and even adopted as the means of stimulating the

proposed effects, but at the same time they impress us with the idea

that a man under such conditions of life and work involuntarily adopts

the gestures of anthropoids. When we see a Zikr, an Islamite rite of

worship, accompanied by obligatory howls and contortions of body, we

are tempted to imagine ourselves in the midst of a troop of wild apes.

And the illusion is still stronger if the performers in the Zikr are

black fakirs, dressed as warriors.

The peripheral nervous system of anthropoids has not, up to this

time, been analyzed with the completeness we could wish. As far as

the observations of Vrolik, Gratiolet, and Alix go, together with my

personal experience in this department, no marked distinction can be

established between the structure of these organs in anthropoids and

those of the nervous system in man.

H. von Ihering has studied the relation of the nervous lumbo-sacral

plexus to the vertebral column of men and animals, and has come to

the conclusion that there is the most complete agreement between men

and animals with respect to the relations of the vertebral column to

the peripheral nervous system. According to this author, man, from

the anatomical point of view, stands so completely within the class

of anthropoids, that the attempt to assign to him any other place in

zoology is open to the charge of being biassed by considerations which

have nothing to do with facts.[94]

The organs of the senses in anthropoids do not present any noteworthy

points of difference from these organs in man. I have written, but not

yet published, a treatise on the eyes of these animals, showing their

general agreement with the conditions of the human eye. On the skin

of the fingers and toes of anthropoids developed corpuscles may be

detected which are connected with the sense of touch.

The vascular system of anthropoids has not up to this time been studied

in any exhaustive manner. The heart strongly resembles that organ in

man. In the gorilla, the chimpanzee, and the orang the great arterial

branches have the same relative conditions as in the human organism.

A common origin from one branch of the subclavian artery, and of the

right and left carotid arteries, often occurs in the orang and with

a certain constancy in the gibbon, so far as we can judge from the

researches which have been made up to this time. But we know that this

form of deviation from the common type is not altogether rare in man.

Bischoff and others have justly maintained that the resemblance to man

which is found in these animals in the arrangement of the heart and

larger blood-vessels appears to be connected with their mode of life.

For although their habits are arboreal, this very fact implies that

they are for the most part in an upright position.

The division of the femoral arteries displays a somewhat interesting

deviation from the normal human type. High up near the femoral arch

an artery, accompanied by veins and a large nerve, diverges from the

femoral artery, which extends, together with its accompanying parts,

as far as the back of the foot. In the gorilla this branch pierces the

sartorius.