me hacms op man. 2^i 



said that, admitting the similarity between tlie adult brains of man 

 and apes, they are, nevertheless, in reality, widely different, because 

 they exhibit fundamental differences in the mode of their develop- 

 ment. 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 dif- 

 ference 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 hem- 

 ispheres, while in the human foetus the sulci firp* 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 "f (1. c, p. 39), and the other of a human foetus at the 

 22d or 23d week of uterogestation, in which Gratiolet notes that the 

 insula was uncovered, but that nevertheless "des incisures sement 

 de lobe anterieur, une scissure peu profonde indique la separation du 

 lobe occipital, tres-reduit, d'ailleurs des cette epoque. Le reste de la 

 surface cerebrale est encore absolumentlisse." 



Three views of this brain are given in plate 2, figs. 1, 2, 3, of the 

 work cited, showing the upper, lateral and inferior views of the 

 hemispheres, but not the inner view. It is worthy of note that the 

 figure by no means bears out Gratiolet's description, inasmuch as the 

 fissure (antero-temporal) on the posterior half of the face of the hem- 

 isphere is more marked than any of those vaguely indicated in the 

 anterior half. If the figure is correct, it in no way justifies Gratio- 

 let's conclusion: "II y a done entre ces'cerveaux [those of a Calli- 

 thrix and of a Gibbon] et celui du foetus humain une difference fonda- 

 mental. Chez celui-ci, longtemps avant que les plis temporaux 

 apparaissent, les plis frontaux essayent ^'e^isier" 



Since Gratiolet's time, however, the development of the gyri and 



* " Chez tons les singes, les plis posterieurs se developpent les premiers ; 

 les plis anterieurs se developpent plus tard, aussi la vertebre occipitale et la 

 parietale 8jnt-elles relativement tresgrandes chez le fcetus. L'Hurame pres- 

 ente une exception reniarquable quant a I'epoque de Tapparition 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 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 11 a'agit les plis 

 cerebraux posterieurs sont bien developpes, tandis que les plis du lobe frontal 

 sont a peine indiques." The figure, ht)wever (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 anthropologiques de Gratiolet " (Mem. de 

 la Societe d' Anthropologic de Paris." 1868, p. 3-2), writes thus: *' Gratiolet a 

 eu entre les mains le cerveau d'un foetus de Gibbon, singe eminemment supe- 

 rieur, et tellemeut rapproche de Torang, que des naturalistes tres-competents 

 I'ont range parmi les anthropoides. M. Huxley, par exemple, n'hesite pas sur 

 ce point. En bien, c'est sur le cerveau d'un foetus de Gibbon que Gratiolet a 

 vu " les circonvolvtioit^ du lobe temporosphettoidal d(ja dereloppees wrsqu'll n''exist- 

 ent pas encore de pli>t xur le lobe frotit(d. II etait done bien autorise a dire que, 

 chez I'Homme les circonvolutions apparaissent d'a en w, tandis que chez les 

 singes elles se developpent d'zf? en a." 



