But
it has been said, that, admitting the similarity between the
adult brains of man and apes, they are nevertheless, in reality,
widely different, because they exhibit fundamental differences in
the mode of their development. No one would be more ready than I
to admit the force of this argument, if such fundamental
differences of development really exist. But I deny that they do
exist. On the contrary, there is a fundamental agreement in the
development of the brain in men and apes.
Gratiolet originated the statement that there is a fundamental
difference in the development of the brains of apes and that of
man--consisting in this; that, in the apes, the sulci which first
make their appearance are situated on the posterior region of the
cerebral hemispheres, while, in the human foetus, the sulci first
become visible on the frontal lobes. (76. "Chez tous les singes,
les plis posterieurs se developpent les premiers; les plis
anterieurs se developpent plus tard, aussi la vertebre occipitale
et la parietale sont-elles relativement tres-grandes chez le
foetus. L'Homme presente une exception remarquable quant a
l'epoque de l'apparition des plis frontaux, qui sont les premiers
indiques; mais le developpement general du lobe frontal, envisage
seulement par rapport a son volume, suit les memes lois que dans
les singes:" Gratiolet, 'Memoire sur les plis cerebres de
l'Homme et des Primateaux,' p.
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