The hippocampus major presents several well-marked corrugations on its expanded lower extremity, "quæ huic parti tanquam figuram digitorum pedis tribuunt;"[1] but as they are on its posterior, not on its anterior edge, we are not compelled to contradict Tiedemann's twenty-first corollary, which relates to the hippocampus major, in the same way as our figures compel us to differ from his twenty-second, quoted above, with reference to the hippocampus minor.
It is for the sake of illustrating yet further the important principle, that variability of arrangement is to be expected, rather than wondered at, in organisms as high as those of these apes, that I add the following observations as to the convolutions on the internal aspect of the hemispheres. There is scarcely any indication of a lobulus quadratus, the structure representing it resembles but little the figure of it as given by M. Gratiole in his third plate; whilst, as if in compensation, the superior marginal convolution, spoken of by him as "trèe simple et à peu près lisse" dans l' Orang (page 49 in his Mémoire), presents, in our specimen, abundant and rich convolutions.
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.
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. Upon most other points, I find myself in agreement with most other writers, both as to facts and to inferences; the cumulative weight of the many minor points of agreement and difference, the reader will be best able to appreciate, by massing each order of facts together for himself.
The principles of the idealist teach him that the difference which exists between the soul of man and the life of the beast which perishes, is not one which can be weighed or measured, be drawn or figured, be calculated in inches or ounces. He fearlessly acknowledges that the anatomical truth in this matter lies on the boundary line of the conterminous positions taken up by Buffon and Professor Huxley, respectively; for he feels that yet higher truth is expressed in the golden words but recently rescued from long oblivion—
"On earth there is nothing great but man;
In man there is nothing great but mind."
- ↑ Icones, p. 51.
