STRUCTURE OF THE BRAIN. 199 



"posed to approach this family in other respects, viz., the lower 

 "members of 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, during the past 

 ten years, fully justify the statement which I made in 1863. 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 dif- 

 ferences 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 of 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 be- 

 come 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"" (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 uncovered, but that nevertheless "des incis- 



'" "Chez tous les singes, les plis posterieurs se developpent les pre- 

 "miers; les plis anterieurs se developpent plus tard, aussi la vertebre 

 "occipitale et la parietale sont-elles relativement tresgrandes chez le 

 "foetus L'Homme presente une exception remarquable quant a 

 "I'epoque de I'apparition des plis frontaux, qui sont les premiers in- 

 "diques; mals 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 cerebraux de I'Homme 

 et des Primates,' p. 39, tab. iv. fig. 3. 



" Gratiolet's words are (1. c. p. 39): "Dans le foetus dont il s'agit 

 "les plis cerebraux posterieurs sont bien developpes, tandis que les 

 "plis du lobe frontal sont a. peine Indiques." The figure, however 

 (PI. iv. fig. 3), shows the fissure of Rolando, and one of the frontal 

 sulci, plainly enough. Nevertheless, M. Alix, in his 'Notice sur les 

 travaux anthropologlques de Gratiolet' (Mem. de la Soclete d' Anthro- 

 pologic de Paris, 1868, p. 32), writes thus: "Gratiolet a eu entre les 

 "mains le cerveau d'un foetus de Gibbon, singe eminemment supe- 

 "rieur, et tenement rapproche de I'orang, que des naturalistes tres- 

 "competents I'ont range parmi les anthropoides. M. Huxley, par ex- 

 "emple, n'hesite pas sur ce point. Eh bien, c'est sur le cerveau d'un 

 "foetus de Gibbon que Gratiolet a vu les circonvolutions du lobe tem- 

 "poro-sphenoidal deja developpees lorsqu'il n'existent pas encore de 



