on the contrary, has its cerebellum entirely but his error must become patent even to hidden, posteriorly, by the cerebral lobes, and possesses a large posterior cornu, with a well-developed hippocampus minor. In many of these creatures, such as the Saimiri (Chrysothrix), the cerebral lobes overlap and extend much farther behind the cerebellum, in proportion, than they do in man (Fig. 16); and it is quite certain that, in all, the cerebellum is completely covered be. hind by well-developed posterior lobes The fact can be verified by every one who possesses the skull of any old or new world monkey. For, inasmuch as the brain in all mammals completely fills the cranial cavity, it is obvious that a cast of the interior of the skull will reproduce the general form of the brain, at any rate with such minute and, for the prescut purpose, utterly unimportant ifferences as may result from the absence of the enveloping membranes of the brain in the dry skull. But if such a cast be made in plaster, and compared with a similar cast of he interior of a human skull, it will be obvius that the cast of the cerebral chamber, epresenting the cerebrum of the ape, as completely covers over and overlaps the cast of the cerebellar chamber, representing the cerebellum, as it does in the man (Fig. 20). A careless observer, forgetting that a soft structure like the brain loses its proper shape the moment it is taken out of the skull, may indeed mistake the uncovered condition of the cerebellum of an extracted and distorted brain for the natural relations of the parts himself if he try to replace the brain within the cranial chamber. To suppose that the cerebellum of an ape is naturally uncovered behind is a miscomprehension comparable only to that of one who should imagine that a man's lungs always occupy but a small portion of the thoracic cavity-because they do so when the chest is opened, and their elasticity is no longer neutralized by the pressure of the air. And the error is the less excusable, as it must become apparent to every one who examines a section of the skull of any ape above a Lemur, without taking the trouble to make a cast of it. For there is a very marked groove in every such skull, as in the human skull-which indicates the line of attachment of what is termed the tentorium-a sort of parchment-like shelf, or partition, which, in the recent state, is interposed between the cerebrum and the cerebellum, and prevents the former from pressing upon the latter (see Fig. 16). This groove, therefore, indicates the line of separation between that part of the crania! cavity which contains the cerebrum and that which contains the cerebellum; and as the brain exactly fills the cavity of the skull, it is obvious that the relations of these two parts of the cranial cavity at once informs us of the relations of their contents. Now in man, in all the old world and in all the new worl Simiæ, with one exception, when the face is directed forward this line of attach 21.-Drawings of the cerebral hemispheres of a Man and of a Chimpanzee of the same length, in order to show ve proportions of the parts: the former taken from a specimen, which Mr. Flower, Conservator of the Museum yal College of Surgeons, was good enough to dissect for me; the latter, from the photograph of a similarly dis impanzee's brain, given in Mr. Marshall's paper above referred to. a, posterior lobe; b, lateral ventricle; c cornu; x, the hippocampus minor. ment of the tentorium, or impression for the lateral sinus, as it is technically called, is nearly horizontal, and the cerebral chamber invariably overlaps or projects behind the cerebellar chamber. In the Howler Monkey, or Mycetes (see Fig. 16), the line passes obliquely upward and backward, and the cerebral overlap is almost nil; while in the Lemurs, as in the lower mammals, the line is much more inclined in the same direction, and the cerebellar chamber projects considerably beyond the cerebral. When the gravest errors respecting points so easily settled as this question respecting the posterior lobes can be authoritatively propounded, it is no wonder that matters of observation of no very complex character, but still requiring a certain amount of care, should have fared worse. Any one who cannot see the posterior lobe in an ape's brain is not likely to give a very valuable opinion respecting the posterior cornu or the hippocampus minor. If a man cannot see a church, it is preposterous to take his opinion about its altar-piece or painted window-so that I do not feel bound to enter upon any discussion of these points, but content myself with assuring the reader that the posterior cornu and the hippocampus minor have now been seen-usually, at least as well developed as in man, and often better not only in the Chimpanzee, the Orang, and the Gibbon, but in all the genera of the old world baboons and monkeys, and in most of the new world forms, including the Marmosets. In fact, all the abundant and trustworthy evidence (consisting of the results of careful investigations directed to the determination of these very questions by skilled anatomists) which we now possess leads to the conviction that, so far from the posterior lobe, the posterior cornu, and the hippocampus minor, being structures peculiar to and characteristic of man, as they have been over and over again asserted to be, even after the publication of the clearest demonstration of the reverse, it is precisely these structures which are the most marked cerebral characters common to man with the apes. They are among the most distinctly Simian peculiarities which the human organism exhibits. As to the convolutions, the brains of the apes exhibit every stage of progress, from the almost smooth brain of the Marmoset, to the Orang and the Chimpanzee, which fall but little below Man. And it is most remarkable that, as soon as all the principal suici appear, the pattern according to which they are arranged is identical with that of the corre sponding sulci of man. The surface of the brain of a monkey exhibits a sort of skeleton map of man's, and in the man-like apes the details become more and more filled in, until it is only in minor characters, such as the greater excavation of the anterior lobes, the constant presence of fissures usually absent in man, and the different disposition and proportions of some convolutions, that the Chimpanzee's or the Orang's brain can be structurally distinguished from Man's. So far as cerebral structure goes, therefore, it is clear that Man differs less from the Chimpanzee or the Orang than these do even from the Monkeys, and that the difference be tween the brains of the Chimpanzee and of Man is almost insignificant, when compared with that between the Chimpanzee brain and that of a Lemur. It must not be overlooked, however, that there is a very striking difference in absolute mass and weight between the lowest human brain and that of the highest ape-a difference which is all the more remarkable when we recollect that a full-grown Gorilla is probably pretty nearly twice as heavy as a Bosjes man, or as many an European woman. It may be doubted whether a healthy human adult brain ever weighed less than thirty one or two ounces, or that the heaviest Gorilla brain has exceeded twenty ounces. This is a very noteworthy circumstance, and doubtless will one day help to furnish an explanation of the great gulf which intervenes between the lowest man and the highest ape in intellectual power; but it has lit It is n *I say help to furnish, for I by no means believe that it was any original difference of cerebral q ality, or quantity, which caused that divergence between the human and the pithecoid stirpes, which has ended in the present enormous gulf between them. doubt perfectly true, in a certain sense, that all differ ence of function is a result of difference of s ructure; oi in other words, of difference in the combination o the primary molecular forces of living substance; and, starting from this undeniable axiom, objectors argue that the vast intellectual chasm between the occasionally, and with much seeming plan ibility, Ape and Man implies a corresponding structural chasm in the organs of the intellectual functions, so that, it is said, the non discovery of such vast diferences proves, not that they are absent, but that Science is incompetent to d tect them. A very little consideration, however, will, I think, show the fallacy of this reasoning. Its validity hangs upon the assumption that intellectual power depends altoge her on the brain, whereas the brain is only one condition. out of many on which intellectual manifestations depend, the others being chiefly the organs of the senses and the moter apparatuses, especially those which are concerned in prehension and in the produetion of articulate speech. bral mass and his inheritance of strong intellectA man born dumb, notwithstanding his great cere mal instincts, would be capable of few higher i tellectual manifestations than an Orang or a Chimpan zee, if he were confined to the society of dumb associates. And yet there might not be the slightest discernible difference between his brain and that of a highly intelligent and cultivated person. The dumbness might be the result of a defective structure of the mouth, or of the tongue, or a mere defective innervaion of these parts; or it might re-ult from congenital deafness, caused by some minute defect of the internal ear, which only a careful anatomist could dis Cover. The argument, that because there is an immense difference between a Man's intelligence and an Ape's, therefore there must be an equally immense difference between their brains, appears to me to be about as well based as the reasoning by which one should endeavor to prove that, because there is a 66 great gulf between a watch that keeps accurate time and another that will not go at all, there is therefore a great structural hiatus between the two watches. A hair in the balance-wheel, a little rust on a p nion, a bend in a tooth of the escapement, a something so slight that only the practised eye of the watchmaker can discover it, may be the source of all the differ ence. tle systema value, for the simple reason that, as may be concluded from what has been already said respecting cranial capacity, the difference in weight of brain between the highest and the lowest men is far greater, both relatively and absolutely, than that between the lowest mau and the highest ape. The latter, as has been seen, is represented by, say, twelve ounces of cerebral substance absolutely, or by 32: 20 relatively; but as the largest recorded human brain weighed between 65 and 66 ounces, the former difference is represented by more than 33 ounces absolutely, or by 65: 32 relatively. Regarded systematically, the cerebral differences of man and apes are not of more than generic value, his family distinction resting chiefly ca his dentition, his pelvis, and his lower limos. Thus, whatever system of organs he studied, the comparison of their modifications in the ape series leads to one and the same result that the structural differences which separate Man from the Gorilla and the Chimpanzee are not so great as those which separate the Gorilla from the lower apes. be no justification for placing him - a dist And thus the sagacious foresight of the great lawgiver of systematic zoology, Linnæus, becomes justified, and a century of anatomical research brings us back to his conclusion, that man is a member of the same order (for which the Linnæan term PRIMATES ought to be retained) as the Apes and Lemurs. This order is now divisible into seven families, of about equal systematic value: the first, the ANTHROPINI, contains Man alone; the second, the CATARHINI, embraces the old world apes; the third, the PLATYRHINI, all new world apes, except the Marmosets; the fourth, the ARCTOPITHECINI, contains the Marmosets; the fifth, the LEMU. RINI, the Lemurs-from which Cheiromys should probably be excluded to form a sixth distinct family, the CHEIROMYINI; while the seventh, the GALEOPITHECINI, contains only the flying Lemur Galeopithecus—a strange form which almost touches on the Bats, as the Cheiromys puts on a Rodent clothing, and the Lemurs simulate Insectivora. Perhaps no order of mammals presents us But in enunciating this important truth I with so extraordinary a series of gradations must guard myself against a form of misun- as this-leading us insensibly from the crown derstanding which is very prevalent. I and summit of the animal creation down to find, in fact, that those who endeavor to creatures from which there is but a step, as teach what nature so clearly shows us in this it seems, to the lowest, smallest, and least inmatter are liable to have their opinions telligent of the placental Mammalia. It is as misrepresented and their phraseology garbled if nature herself had foreseen the arrogance until they seem to say that the structural differences between man and even the highest apes are small and insignificant. Let me take this opportunity then of distinctly asserting, on the contrary, that they are great and significant; that every bone of a Gorilla bears marks by which it might be distinguished from the corresponding bone of a man; and that, in the present creation, at any rate, no intermediate link bridges over the gap between Homo and Troglodytes. of man, and with Roman severity had provided that his intellect, by its very triumphs, should call into prominence the slaves, admonishing the conqueror that he is but dust. 'These are the chief facts, this the immediate conclusion from them to which I adverted in the commencement of this Essay. The facts, I believe, cannot be disputed; and if so, the conclusion appears to me to be inevitable. It would be no s, wrong than absurd to But if Man be separated by no greater deny the existence of this chasın; but it is at structural barrier from the brutes than they least equally wrong and absurd to exaggerate are from one another-then it seems to fciits magnitude, and, testing on the admitted low that if any process of physical causation fact of its existence, refuse to inquire can be discovered by which the genera and whether it is wide or narrow. Remember, families of ordinary animals have been pro if you will, that there is no existing link duced, that process of causation is amply between Man and the Gorilla, but do not for- sufficient to account for the origin of Man. get that there is a no less sharp line of de- In other words, if it could be shown that the marcation, a no less complete absence of any Marmosets, for example, have arisen by gradtransitional form, between the Gorilla and the ual modification of the ordinary Platyrhini, Orang, or the Orang and the Gibbon. I say or that both Marmosets and Platyrhini are not less sharp, though it is somewhat nar- modified ramifications of a primitive stockrower. The structural differences between then there would be no rational ground for Man and the Man-like apes certainly justify doubting that man might have originated in our regarding him as constituting a family the one case by the gradual modification of apart from them; though inasmuch as he differs less from them than they do from other families of the same order, there can And believing, as I do, with Cuvier, that the pos session of articulate speech is the grand distinctive character of man (whether it be absolutely peculiar 10 him or not, I find it very easy to comprehend that Some equally inconspicuous structural difference may have been the primary cause of the immeasurable and pineally infinite divergence of the tuman from the Staan Stirps. a man-like ape, or in the other case as a ramification of the same primitive stock as those apcs. At the present moment but one such process of physical causation has any evidence in its favor; or, in other words, there is but one hypothesis regarding the origin of species of animals in general which has any scientific existence-that propounded by Mr. Darwin. For Lamarck, sagacious as many of his views were, mingled them with so much long as one link in the chain of evidence is that was crude, and even absurd, as to neu- wanting; and so long as all the animals and tralize the benefit which his originality might plants certainly produced by selective breedhave effected had he been a more sober and ing from a common stock are fertile, and cautious thinker; and though I have heard their progeny are fertile with one another, of the announcement of a formula touching that link will be wanting. For, so long, sethe ordained continuous becoming of or- lective breeding will not be proved to be ganic forms," it is obvious that it is the first competent to do all that is required of it to duty of a hypothesis to be intelligible, and produce natural species. that a qua-qua-versal proposition of this kind, which may be read backward, or forward, or side-ways, with exactly the same amount of signification, does not really exist, though it may seem to do so. At the present moment, therefore, the question of the relation of man to the lower animals resolves itself, in the cad, into the larger question of the tenability or untenability of Mr. Darwin's views. But here we enter upon difficult ground, and it behooves us to define our exact position with the greatest care. It cannot be doubted, I think, that Mr. Darwin has satisfactorily proved that what he terms selection, or selective modification, must occur, and does occur, in nature; and he has also proved to superfluity that such selection is competent to produce forms as distinct, structurally, as some genera even are. If the animated world presented us with none but structural differences, I should have no hesitation in saying that Mr. Darwin has demonstrated the existence of a true physical cause, aimply competent to account for the origin of living species, and of man among the rest. But, in addition to their structural distinctions, the species of animals and plants, or at least a great number of them, exhibit physiological characters—what are known as distinct species, structurally, being for the most part either altogether incompetent to breed one with another; or if they breed, the resulting mule, or hybrid, is unable to perpetuate its race with another hybrid of the same kind. A true physical cause is, however, admitted to be such only on one condition-that it shall account for all the phenomena which come within the range of its operation. If it is inconsistent with any one phenomenon, it must be rejected; if it fails to explain any one phenomenon, it is so far weak, so far to be suspected, though it may have a perfect right to claim provisional acceptance. Now Mr. Darwin's hypothesis is not, so far as I am aware, inconsistent with any known biological fact; on the contrary, if admitted, the facts of Development, of Comparative Anatomy, of Geographical Distribution, and of Paleontology, become connected together, and exhibit a meaning such as they never possessed before; and I, for one, am fully convinced that if not precisely true, that hypothesis is as near an approximation to the truth as, for example, the Copernican hypothesis was to the true theory of the planetary motions. But, for all this, our acceptance of the Darwinian hypothesis must be provisional so I have put this conclusion as strongly as possible before the reader, because the last position in which I wish to find myself is that of an advocate for Mr. Darwin's, or any other views-if by an advocate is meant one whose business it is to smooth over real diflìcultics, and to persuade where he cannot convince. In justice to Mr. Darwin, however, it must be admitted that the conditions of fertility and sterility are very ill understood, and that every day's advance in knowledge leads us to regard the hiatus in his evidence as of less and less importance, when set against the multitude of facts which harmonize with, or receive an explanation from, his doctrines. I adopt Mr. Darwin's hypothesis, therefore, subject to the production of proof that physiological species may be produced by selective breeding; just as a physical philosopher may accept the undulatory theory of light, subject to the proof of the existence of the hypothetical ether; or as the chemist adopts the atomic theory, subject to the proof of the existence of atoms; and for exactly the same reasons, namely, that it has an immense amount of primâ facie probability: that it is the only means at present with reach of reducing the chaos of observcd facts to order; and, lastly, that it is the most powerful instrument of investigation which has been presented to naturalists since the invention of the natural system of classification and the commencement of the systematic study of embryology. But even leaving Mr. Darwin's views aside, the whole analogy of natural operations furnishes so complete and crushing an argument against the intervention of any but what are termed secondary causes, in the production of all the phenomena of the universe, that, in view of the intimate relations between Man and the rest of the living world, and between the forces exerted by the latter and all other forces, I can see no excuse for doubting that all are cc-ordinated terms of nature's great progression, from the formless to the formed from the inorganic to the organic-from blind force to conscious intellect and will. Science has fulfilled her function when she has ascertained and enunciated truth; and were these pages addressed to men of science only, I should now close this Essay, knowing that my colleagues have learned to respect nothing but evidence, and to believe that their highest duty lies in submitting to it, however it may jar against their inclinations. But desiring, as I do, to reach the wider circle of the intelligent public, it would he unworthy cowardice were I to ignore the repugnance with which the majority of my readers are likely to meet the conclusions to which the most careful and conscientious study I have been able to give to this matter has led me. On all sides I shall hear the cry, “We are men and women, and not a mere better sort of apes, a little longer in the leg, more compact in the foot, and bigger in brain than your brutal Chimpanzees and Gorillas. The power of knowledge-the conscience of good and evil--the pitiful tenderness of human affections, raise us out of all real fellowship with the brutes, however closely they may seem to approximate us. To this I can only reply that the exclamation would be most just, and would have my own entire sympathy, if it were only relevant. But it is not I who seek to base Man's dignity upon his great toe, or insinuate that we are lost if an Ape has a hippocampus minor. On the contrary, I have done my best to sweep away this vanity. I have endeavored to show that no absolute structural line of demarcation, wider than that between the auimals which immediately succeed us in the scale, can be drawn between the animal world and ourselves; and I may add the expression of my belief that the attempt to draw a physical distinction is equally futile, and that even the highest faculties of feeling and of intellect begin to germinate in lower forms of life. At the same time no one is more strongly convinced than I am of the vastness of the gulf between civilized man and the brutes; or is more certain that whether from them or not, he is as suredly not of them. No one is less disposed to think lightly of the present dignity, or despairingly of the future hopes, of the only consciously intelligent denizen of this world. We are indeed told by those who assume authority in these matters that the two sets of opinions are incompatible, and that the belief in the unity of origin of man and brutes involves the brutalization and degradation of the former. But is this really so? Could not a sensible child confute, by obvious arguments, the shallow rhetoricians who would force this conclusion upon us? Is it indeed true that the Poet, or the Philosopher, or the Artist whose genius is the glory of his age, is degraded from his high estate by the undoubted historical probability, not to say certainty, that he is the direct descendant of some naked and bestial savage, whose intelligence was just sufficient to make him a little more cunning than the Fox, and by so much more dangerous than the Tiger? Or is he bound to howl and grovel on all fours because of the wholly unquestionable fact that he was once an egg, which no ordinary power of discrimination could distinguish from that of a Dog? Or is the philanthropist or the saint to give up his endeavors to lead a noble life because the simplest study of man's nature reveals, at its foundations, all the selfish passions and fierce appetites of the mercst quadruped? Is mother-love vile because a hen shows it, or fidelity base because dogs possess it? The common-sense of the mass of mankind will answer these questions without a moment's hesitation. Healthy humanity, finding itself hard pressed to escape from real sin and degradation, will leave the brooding over speculative pollution to the cynics and the rightous "overmuch," who, disagreeing in everything else, unite in blind insensibility to the nobleness of the visible world, and in inability to appreciate the grandeur of the place Man occupies therein. Nay, more; thoughtful men, once escaped from the blinding influences of traditional prejudice, will find in the lowly stock whence man has sprung the best evidence of the splendor of his capacities, and will discern in his long progress through the Past a reasonable ground of faith in his attainment of a nobler Future. They will remember that in comparing civilized mau with the animal world one is as the Alpine traveller, who sees the mountains soaring into the sky, and can hardly discern where the deep-shadowed crags and roseate peaks end, and where the clouds of heaven begin. Surely the awe-struck voy. ager may be excused if at first he refuses to believe the geologist, who tells him that these glorious masses are, after all, the hardened mud of primeval seas, or the cooled slag of subterranean furnaces-of one substance with the dullest clay, but raised by inward forces to that place of proud and seemingly inaccessible glory. But the geologist is right; and due reflection on his teachings, instead of diminishing our reverence and our wonder, adds all the force of intellectual sublimity to the more æsthetic intuition of the uninstructed beholder. And after passion and prejudice have died away, the same result will attend the teachings of the naturalist respecting that great Alps and Andes of the living world-Man. Our reverence for the nobility of manhood will not be lessened by the knowledge that Man is, in substance and in structure, one with the brutes; for he alone possesses the marvellous endowment of intelligible and rational speech whereby, in the secular period of his existence, he has slowly accumulated and orgauized the experience which is almost wholly lost with the cessation of every individual life in other animals; so that now he stands raised upon it as on a mountain-top. far above the level of his humble fellows, and transfigured from his grosser nature by reflecting, here and there, a ray from the infinite source of truth. A SUCCINCT HISTORY OF THE CONTROVERSY RESPECTING THE CEREBRAL STRUCTURE OF MAN AND THE APES. UP to the year 1857 all anatomists of authorty, who had occupied themselves with the cerebral structure of the Apes-Cuvier, Tiedemann, Sandifort, Vrolik, Isidore G. St. Hilaire, Schroeder van der Kolk, Gratiolet |