STRUCTURE OF THE BRAIN. 197 



the smaller Platyrliml; rudimentary In Pithecia;" and more or 

 less obliterated by bridging convolutions in Ateles. 



A character which is thus variable within the limits of a single 

 group can have no great taxonomic value. 



It is further established, that the degree of asymmetry of the 

 convolution of the two sides in the human brain is subject to 

 much individual variation; and that, in those individuals of the 

 Bushman race who have been examined, the gyri and sulci of the 

 two hemispheres are considerably less complicated and more sym- 

 metrical than in the European brain, while, in some individuals 

 of the chimpanzee, their complexity and asymmetry become no- 

 table. This is particularly the case in the brain of a young male 

 chimpanzee figured by M. Broea. ('L'ordre des Primates,' p. 165, 

 fig. 11.) 



Again, as respects the question of absolute size, it is estab- 

 lished that the difference betv/een the largest and the smallest 

 healthy human brain Is greater than the difference between the 

 smallest healthy human brain and the largest chimpanzee's or 

 orang's brain. 



Moreover, there is one circumstance in which the orang's and 

 chimpanzee's brains resemble man's but in which they differ from 

 the lower apes, and that is the presence of two corpora candicantia 

 —the Cynomorpha having but one. 



In view of these facts I do not hesitate in this year 1874, to re- 

 peat and insist upon the proposition which I enunciated in 186S.'* 



"So far as cerebral structure goes, therefore, it is clear that man 

 "differs less from the chimpanzee or the orang, than these do even 

 "from the monkeys, and that the difference between the brain of 

 "the chimpanzee and of man is almost insignificant, when com- 

 "pared with that between the chimpanzee brain and that of a Le- 

 "mur." 



In the paper to which I have referred. Professor Bischoff does 

 not deny the second part of this statement, but he first makes the 

 irrelevant remark that it is not wonderful if the brains of an orang 

 and a Lemur are very different; and secondly, goes on to assert 

 that, "if we successively compare the brain of a man with that of 

 "an orang; the brain of this with that of a chimpanzee; of this 

 "with that of a gorilla, and so on of a Hylobates, Semnopithecus, 

 "Cynocephalus, Cercopithecus, Macacus, Cebus, Callithrix, Lemur, 

 "Stenops, Hapale, we shall not meet with a greater or even as 

 "great a break in the degree of development of the convolutions, 

 "as we find between the tarain of a man and that of an orang or 

 "chimpanzee." 



™ FloT,'er 'On the Anatomy of Pithecia Monachus,' 'Proceedings of 

 the Zoological Society,' 1S62. 

 '» 'Man's Place in Nature.' p. 102. 

 14 



