George Rolleston

“ It will teach men mundum quærere non in microcosmo suo sed in mundo majore, to hold of Nature that her ways are not as our ways, nor her thoughts as our thoughts. The notion of type may help man's weakness, but it by no means therefore follows that it regulates Nature's operations; it may enable us to colligate phenomena, but it may no more for that be the cause of their evolution than the mule's panniers which carry home the grapes are, by virtue of this their function, the cause of the growth of the vine. ”

“ As to the external anatomy, whilst too little importance has perhaps been assigned to the points of difference which the very widely-differing heights of the hemispheres, the very widely-differing antero-posterior diameters of the corpora callosa, and of the frontal lobes, and the very widely-differing absolute weights of the two brains, constitute, too much seems to have been given to the "absence of an external perpendicular fissure," to the "presence of a lobule of the marginal convolution," and to the lesser relative size of the nerves in the human brain. ”

“ Though the Brain in each is the same—in the one the power of thought exists, in the other it is absent. Thought, therefore, cannot be a product of the Material Organism—"Il ne pense pas—y a-t-il une preuve plus evidente que la matière seule, quoique par- faitement organisée, ne peut produire, ni la pensée, ni la parole qui en est la signe, à moins qu' elle ne soit animée par un principe supérieur?" ”

“ Tiedemann's figure of the chimpanzee's brain leads us, by its imperfectly-marked operculum, to the same conclusion as its sharply drawn one did in the case of the orang. The law of correlation of forms is a safe guide to us, when we have to predict what will be found in the lower organisms of well-marked families; it loses its in- flexibility, and becomes but a leaden rule, when we come to examine the most perfectly evolved species in such families. In the higher species of the order, apes, as in the higher varieties of the species, man, we find variability the rule, uniformity the exception ”

“ The evolution of the one structure has rendered possible the evolution of the other, by setting free some residual product which Nature in her economy has worked up into such secondary structure. The perfecting of the plumage contemporaneously with the perfecting of the sexual functions in the pairing bird is one, and may serve as a type of all, of the instances given by Mr. Paget. There is no equality in rank between the two structures, which stand to each other in this relation of complemental nutrition; the one is supported by what the other finds useless, superfluous, or even hurtful ”

“ He may make his strong position yet stronger, we believe, by adducing biological evidence in disproof of the usually granted assumption, that mental capacity stands always in a certain relation to cerebral development; but holding, as he does, the existence of an essential difference between mind and matter, he makes himself but a materialist for the nonce, if he express any repugnance to such statements as those just quoted on account of any conclusions to which they could lead him. ”

“ In the orang, and in the chimpanzee, both the frontal, 1, 2, 3, the 4 and 5 ascending parietal, and the superior bridging convolutions aa, are asymmetrical on the two sides of the brain. The occipital d, the temporo-sphenoidal b, and the convolutions b, b, b, named "pli courbe" by M. Gratiolet, are symmetrical in the chimpanzee, but asymmetrical in the orang. The occipital lobe is both more simple and more symmetrical in the chimpanzee than in the orang, but it is not larger in size. Both ascending convolutions are a little more simple in the chimpanzee than in the orang. ”

“ The internal anatomy of the simious brain does not furnish us, then, with those sharply differentiating characteristics which have been supposed to put it into a position of such marked inferiority to that of man. ”

“ A line drawn along the edge of the cerebral hemisphere in Fig. 1, where that hemisphere overlies the cerebellum, will be seen to be much less nearly horizontal than a line is which holds the same relation in a human brain. It seems as if the cerebellum had encroached upon the cerebral lobes which roofed it over.
The same figure shows that a similar stunting has befallen the upward growth of both the frontal and posterior lobes, a line bounding the superior edge of the hemispheres from D forwards to A, describing a much more even curve than is usual in man. ”

“ Philosophers of other countries have often taken occasion to remark, and in no complimentary terms, upon the utilitarian tendency constantly displayed by the English mind. Our everlasting seeking after hidden purposes, our infantine inquisitiveness after final causes in biological as well as other investigations, has frequently called forth contemptuous comments from foreigners, who happened to be acquainted with Bacon's famous comparison of final causes to vestal virgins. ”

“ There is yet a third structure—"the Lobule of the Marginal Convolution"—to be treated of. In man it lies above the upper end of the fissure of Sylvius; and it may not unfairly be represented in our figure 1, by the convolution which lies immediately to the spectator's left of 5. Of it M. Gratiolet speaks in the following language:—"Cet lobule est particulier à l'homme et ne se trouve pas [27] ni dans l'orang ni dans le chimpanzee." ”

“ Let us suppose that the Negro, the weight of whose brain, as given by Tiedemann, amounted to no more than 26 oz., weighed altogether as much as 8 stone, or 1792 oz. The proportion between his brain's weight and his body's would then have stood as 1 : 68.9, as against a proportion taken between analogous weights in the apes of 1 : 81.3. It will be seen from this that the absolute weight of the human brain is a more sharply differentiating characteristic than is its relative weight. ”

“ Tiedemann's Icones of the lower apes are unanimous on the same side, but the figures which he gives of the brains of the orang and chimpanzee, in his work on the Brain of the Negro, [7] represent the cerebellum uncovered, on both sides, to a somewhat greater extent than it is in our figures 3 and 4, on one side [8] .
A careful study, however, of our figures, coupled with an examination of the skulls of several anthropoid apes, will lead to the belief that the cerebral hemispheres of the apes bulge less laterally than do those of man ”

“ The variability which we have seen to exist in the species chimpanzee, is no inconsiderable proof of its high relative rank in its own order.
But there is a second connecting bridge passing between the occipital and the parietal lobes. ”

“ After the removal of the dura mater, a small segment of cerebellar surface became visible on each side, posteriorly to the tips of the occipital lobes. It is well known [3] that the anteroposterior dimensions of the corpus callosum are very different in a brain whilst contained and supported within its case, and when removed from the skull,—the forward swaying of the hemispheres upon their supporting stems, the crura, flattening the previously arched commissure. ”

“ The roof-like exterior of the skull of the gorilla would prepare us for meeting with quite another relation of cerebellum and cerebrum than that which we find in the subglobular skulls of the smaller anthropoid apes. ”

“ This convolution is invariably present, and invariably superficially placed in man; it is as invariably absent in both the anthropoid apes. In man it is always a large, easily recognizable structure; and in cases such as those which our fourth human brain may be taken to exemplify, or exaggerate, it will often be found to send a branch, as it were, in aid of the weakened superior bridge. The vacuity which in the apes corresponds to what is invariably a convolution of importance in man, may be seen in fig. ”

“ These structures, fixed and settled in the adult organism, speak of a time when the sex was as yet unfixed and unsettled in the developing embryo, and accessory organs of either kind were, if so we may say, prepared so as to be in readiness to meet either event. The mammary glands, the Weberian organ, and the cysts of Morgagni of the adult male, the round ligament and the canals of Nuck and of Gärtner of the adult female economy, may have the history of their existence thus read. ”

“ Though we may be inclined to consider the diminution in lateral expanse, and in backward growth of the posterior lobes, D, of which our figures speak, as an individual rather than as a specific peculiarity, we are compelled to assign greater importance to the curtailment in downward growth to which they, as well as other similar figures, testify. ”

“ But in these latter days it has come to be acknowledged, even in England, that there are many structures in normal organisms for the existence of which no teleological explanation will suffice; and it is right to say that in no other country, and in no other time than ours, have theories for the explanation of such phenomena been more clearly enunciated. ”

“ The second canon is but a converse of the first; and, expressed in similar language, it may run thus:—If certain structures, or certain relations of certain structures, are found to exist in animals confessedly higher in the scale of life than those which are the subjects of comparison, such structures, or such relations of such structures, cannot by themselves be held to be marks of serial degradation. ”

“ Cerebellum.
d. Occipital lobes.
e. Medulla oblongata.
f. Fissure of Sylvius.
g. Pons.
a. Convolution connecting the superior occipital convolution (10) , to the lobule of the 2nd ascending parietal 5'. ↑ Histoire Naturelle, tom xiv., p. 61. Paris, 1766. ↑ Icones, Cor. xxxii, p. 54. ↑ "Bei der Messung der Lange des Balkens muss man wohl im Auge behalten dass man ihn Misst so lange die Hemisphären ihre Lage noch in Schädel haben; am herausgenommenen Gehirn dehnt er sich sehr betractlich in die Lange aus und verliert seine Wolbung." Huschke. Schaedel, Him und Seele, p. 110. ”