STRUCTURE OF THE BRAIN. 195 



lished a memoir™ on the cerebral convolutions of man and apes; 

 and as the purpose of my learned colleague was certainly not to 

 diminish the value of the differences between apes and men 

 in this respect, I am glad to make a citation from him. 



"That the apes, and especially the orang, chimpanzee and gorilla, 

 "come very close to man In their organization, much nearer than 

 "to any other animal, is a well-known fact, disputed by nobody. 

 "Looking at the matter from the point of view of organization 

 "alone, no one probably would ever have disputed the view of 

 "Linnaeus, that man should be placed, merely as a peculiar species, 

 "at the head of the mammalia and of those apes. Both show, in 

 "all their organs, so close an affinity, that the most exact anatomi- 

 "cal investigation is needed in order to demonstrate those dif- 

 "ferences which really exist. So it is with the brains. The brains 

 "of man, the orang, the chimpanzee, the gorilla, in spite of all the 

 "important differences which they present, come very close to one 

 "another" (1. c. p. 101). 



There remains, then, no dispute as to the resemblance in funda- 

 mental characters, between the ape's brain and man's; nor any 

 as to the wonderfully close similarity between the chimpanzee, 

 orang and man, in even the details of the arrangement of the 

 gyri and sulci of the cerebral hemispheres. Nor, turning to the 

 differences between the brains of the highest apes and that of man, 

 is there any serious question as to the nature and extent of these 

 differences. It Is admitted that the man's cerebral hemispheres 

 are absolutely and relatively larger than those of the orang and 

 chimpanzee; that his frontal lobes are less excavated by the up- 

 ward protrusion of the roof of the orbits; that his gyri and sulci 

 are, as a rule, less symmetrically disposed, and present a greater 

 number of secondary plications. And it is admitted that, as a rule, 

 in man, the temporo-occlpital or "external perpendicular" fissure, 

 which is usually so strongly marked a feature of the ape's brain 

 is but faintly marked. But it is also clear, that none of these dif- 

 ferences constitutes a sharp demarcation between the man's and 

 the ape's brain. In respect to the external perpendicular fissure 

 of Gratlolet, in the human brain, for instance, Professor Turner 

 remarks:"- 



"In some brains it appears simply as an indentation of the mar- 

 "gin of the hemispheres, but, in others, it extends for some distance 

 "more or less transversely outwards. I saw it in the right hemls- 

 "phere of a female brain pass more than two inches outwards; 

 "and in another specimen, also the right hemisphere, it proceeded 



™ 'Die Grosshirn-Windungen des Menschen;' 'Abhandlungen der K. 

 Bayerisohen Akademie,' Bd. x., 1868. 



''I 'Convolutions of the Human Cerebrum Topographically Consid- 

 ered,' 1S66, p. 12. 



