Association, to find myself compelled to give a diametrical contradiction to certain assertions respecting the differences which obtain between the brains of the higher apes and of man, which fell from Professor Owen; and in the interest of science, it is well that the real or apparent opposition of competent inquirers, as to matters of fact, should be put an end to as soon as possible, by the refutation of one or the other. Happily, it is unnecessary that I should trust to my memory of what took place on the occasion to which I refer; for the assertions alluded to were already familiar to me, inasmuch as their substance occurs in two of Professor Owen's latest works—the paper "On the Characters, Principles of Division, and Primary Groups of the Class Mammalia," read before the Linnæan Society on February 17th, and April 21st, 1857; and the essay "On the Classification of the Mammalia," delivered as a lecture before the University of Cambridge.
I quote from the former essay, as that intended for an audience of experts, and hence, in all probability, to be regarded as more strictly scientific:—
"In man, the brain presents an ascensive step in development, higher and more strongly marked than that by which the preceding sub-class was distinguished from the one below it. Not only do the cerebral hemispheres (figs. 5 & 6 A) overlap the olfactory lobes and cerebellum, but they extend in advance of the one, and further back than the other (fig. 6, C). Their posterior development is so marked, that anatomists have assigned to that part the character of a third lobe; it is peculiar to the genus Homo, and equally peculiar is the posterior horn of the lateral ventricle, and the 'hippocampus minor,' which characterise the hind lobe of each hemisphere. Peculiar mental powers are associated with this highest form of brain, and their consequences wonderfully illustrate the value of the cerebral character; according to my estimate of which I am led to regard the genus Homo as not merely a representative of a distinct order, but of a distinct sub-class of the Mammalia,[1] for which I propose the name of 'Archencephala' (fig. 6)."
It might be a grave question whether, granting the existence of the differences assumed to distinguish the human brain, they would justify the establishment of a sub-class for the genus Homo; but that difficulty is not worth discussing, inasmuch as I shall endeavour to demonstrate, in the course of the following pages, the accuracy of the three counter statements which I made to the audience assembled in Section D, viz.:—
1. That the third lobe is neither peculiar to, nor characteristic of man, seeing that it exists in all the higher Quadrumana.
2. That the posterior cornu of the lateral ventricle is neither peculiar to, nor characteristic of man, inasmuch as it also exists in the higher Quadrumana.
3. That the Hippocampus minor is neither peculiar to, nor characteristic of man, as it is found in certain of the higher Quadrumana.
I support the first two propositions by the evidence of every original observer who has written upon the subject, including Professor Owen
- ↑ Here occurs the note which I have already quoted at p. 69. The italics in the above extract are my own.
