Chap. VII. Structure of the Brain 203 



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

 " posterior lobes, there is no approximation to the Lemuiine, short 

 ■* hemisphered, brain, in those monkeys which aie commouly supposed 

 ■* to approiioli this family in other rcspecls, viz., the lower members of 

 " the Platyrhiue group." 



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

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

 researches of so many invesHg.itois, duiing tlie pa.st ten years, fully 

 justify the statement which I made in IStiS. Bdt it has been said 

 that, admitting the similarity between tl.e adult brains of man and 

 upes, they are nevertheless, in reality, widely different, because they 

 exhibit fnudamental ditferences in the mode of their development. No 

 one would be more ready than I to admit the force of this aigumeiit, if 

 such fundamental differences of development really exiist. But I dmy 

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

 ment in the development of the brain in men and apes. 



Gratiolet or ginated the staiement that there is a fundamental 

 difference in the development of the brains of apes and that of man — • 

 consisting in this; that, in the npes, the sulci which first make their 

 appearance are situated on the po.-terior region of the cerebral hemi- 

 spheres, while, in the human fujtus, tiie sulci first become visible ou the 

 frontal lobes." 



This general statement is ba.ed upcm 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), anil the other of a human Icetus at the 22ud or 23rd week 

 of uterofjestation, in wi.ich Gratiolet notes that the insula was un- 

 covered, but that neveitheless " des incisures sbment ie lobe antcrieiu'. 

 " une scissure peu profonde indique la s^p,. ration du lobe occipital, tre»- 



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



** postdrieurs se developpent les pre- sulci, plainly enough. Nevertheless, 



" miers ; les plis ant^rieurs se M. Alix, in his * Notice sur les 



" developpent plus tai'd, aussi la travaux anthropologiques de Gratio- 



*' vertfebre occipitale et la pari^tale let ' (M^m. de la Soci^te' d'Anthro- 



" sont-elles relati\emeut trfes-grandes pologie de Paris,' 1868, p. 32), 



" chez le fcetus. L'Homme presente writes thus : " Gratiolet a en outre 



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



" a r^poque de Tapparitiou des plis " Gibbon, singe ^minemment su- 



** frontaux, qui sont les premiers " pdrieur, et tellement rapprochi^ de 



" indiqu^s ; mais le d^veloppement " I'orang, que des naturalistes tres- 



'* g^ndral du lobe frontal, envisag(5 " corop^tents I'ont rang^ pavmi les 



" seulement par i-ajiport 4 son '' anlhropoi'des. M. Huxley, par ex- 



" volunie,suitlesmemesloisquedans " eniple, n'hesite pas sur ce puint. 



" les singes:" Gratiolet, 'Mdmoire " Eh bien, c'est sur le cerveau d'un 



sur les plis cii'ebraux de I'Homme " foitas de Gibbon que Gratiolet ,x 



et des Primates,' p. 39, tab. iv. " vu fes circonvolutions du lobe tern- 



fig, 3. " poro-spMnoidal deja deveioppecs 



'' Gratiolet's words are (I. c. p. " hrsgu'U n'existent pas encore de plia 



39) : " Dans le fcetus dont il s'agit " sur le lobe frontal. II ^tait done 



" les plis cerebraux post^rieurs sont " bien autoris^ a dire que, chez 



" bien d^velopp^s, tandis que les " I'homme les circonvolutions appa- 



" plis du lobe frontal sont k peine " raissent d'o en w, tandis que chea 



" indiqiies." The figure, however " les singes elles se diiveloppeu* 



fl'l. iv. fig. 3"). shews t£ie fissure of " d'to en o." 



