Chap. VII. Structure of the Brain. 203 



"And it is especially remarkable that, in the development of the 

 a posterior lobes, there is no approximation to the Lemurine, short 

 ** hemisphered, brain, in those monkeys which are commonly supposed 

 *' to approach this family in other respects, viz., the lower members of 

 u the Platyrhine group." 



So far as the structure of the adult brain is concerned, then, the very 

 considerable additions to our knowledge, which have been made by the 

 researches of so many investigators, duiing the past ten years, fully 

 justify the statement which I made in 1S(J3. 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 

 Buch fundamental differences of development really exist. But I deny 

 that they do exist. On the contrary, there is a fundamental agree- 

 ment 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 hemi- 

 spheres, while, in the human foetus, the sulci first become visible on the 

 frontal lobes.™ 



This general statement is based upon two observations, the one of a 

 Gibbon almost ready to be born, in which the posterior gyri were " well 

 *' developed," while those of the frontal lobes were " hardly indicated ' rr 

 (1. c. p. 39), and the other of a human foetus at the 22nd or 23rd week 

 of uterogestation, in which Gratiolet notes that the insula was un- 

 covered, but that nevertheless " des incisures sement le lobe anterieur. 

 " une scissure peu profonde indique la separation du lobe occipital, tres- 



76 " Chez tous les singes, les plis Rolando, and one of the frontal 

 " posterieurs se developpent les pre- sulci, plainly enough. Nevertheless, 

 " miers ; les piis anterieurs se M. Alix, in his 'Notice sur les 

 " developpent plus tard, aussi la travaux anthropologiques de Gratio- 

 " vertebre occipitale et la parietale let ' (Mem. de la Societe d'Anthro- 

 "sont-ellesrelativementtres-grandes pologie de Paris,' 1868, p. 82), 

 " chez le foetus. L'Homme presente writes thus : " Gratiolet a eu outre 

 " une exception remarquable quant " les mains le cerveau d'un foetus de 

 " a l'epoque de Fapparitiou des plis " Gibbon, singe eminemment su- 

 " frontaux, qui sont les premiers " perieur, et tellement rapproche de 

 " indiques ; mais le developpement " l'orang, que des natural istes tres- 

 " general du lobe frontal, envisage " coripetents l'ont range parmi les 

 " seulement par rapport a son " anthropoides. M. Huxley, par ex- 

 " volume, suit les memeslois que dans " emple, n'hesite pas sur ce point. 

 " les singes :" Gratiolet, ' IMemoire " Eh bien, e'est sur le cerveau d'un 

 sur les plis ce'rebraux de l'Homme " foetus de Gibbon que Gratiolet a 

 et des Primates,' p. 39, tab. iv. u vu les cir convolutions du lobe tern- 

 fig. 3. " poro-sphenoidal deja deve/o])pees 



77 Gratiolet's words are (1. c. p. " lorsqu'iln 'existent pas encore de plis 

 39): "Dans le foetus dont il s'agit " snr le lobe frontal. 11 etait done 

 " les plis cerebraux posterieurs sont *' bien autorise a dire que, chez 

 " bien developpes, tandis que les " l'homme les circonvolutious appa- 

 " plis du lobe frontal sont a peine " raissent d'a en w, tandis que che? 

 " indiques." The figure, however " les singes elles se developpent 

 (PI. iv. fig. 3), shews tuie fissure of " d'eo ea a." 



