TBE RACES OF MAN. 22^ 



animal wbicli have, up to tliis time, been figured or described. Tbe 

 superficial position of tbe second bridging convolution is evidently 

 less frequent, and bas as yet, I believe, only been seen in tbe brain 

 (A) recorded in tbis communication. Tbe asyunnetrical arrangement 

 in tbe convolutions of tbe two bemispberes, wbicb previous observ- 

 ers bave referred to in their descriptions, is also well illustrated in 

 these specimens " (pp. 8, 9). 



Even were the presence of the temporo-occipital, or external per- 

 pendicular, sulcus, a mark of distinction between tbe higher apes 

 and man, tbe value of such a distinctive character would be ren- 

 dered very doubtful by tbe structure of the brain in the Platyrrbine 

 apes. In fact, while the temporo-occipital is one of tbe most con- 

 stant of sulci in the Catarrbine, or Old World, apes, it is never very 

 strongly developed in tbe New World apes; it is absent in tbe smaller 

 Platy rrhini ; rudimentary in Pithecia ;* and more or less obliterated 

 by bridging convolutions in Ateles. 



A character wbicb is thus variable within tbe limits of a single 

 group can bave no great taxonomic value. 



It is further established that the degree of asymmetry of tbe con- 

 volution of the two sides in the human brain is subject to much indi- 

 vidual variation; and that, in those individuals of the Bushman 

 race who have been examined, tbe gyri and sulci of the two hemis- 

 pheres are considerably less complicated and more symmetrical than 

 in tbe European brain, while, in some individuals of the chimpanzee, 

 their complexity and asymmetry become notable. This is particu- 

 larly the case in the brain of a young male chimpanzee figured by M. 

 Broca (" L'ordre des Primates," p. 165, fig. 11). 



Again, as respects the question of absolute size, it is established 

 that tbe difference between the largest and the smallest healthy 

 human brain is greater than the difference between tbe smallest 

 healthy human brain and the largest chimpanzee's or orang's brain. 



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

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

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

 Gynomorpha having but one. 



In view of these facts 1 do not hesitate in this year, 1874, to 

 repeat and insist upon the proposition which I enunciated in 1863:f 



" 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 tbe difference between the brain of the 

 chimpanzee and of man is almost insignificant when compared with 

 that between the chimpanzee brain and that of a Lemur." 



In the })aper to wbicb I have referred, Prof. Bischoff does not 

 deny the second part of tbis statement, but he first makes the irrele- 

 vant 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 tbe brain of a man with that of an orang; 

 the brain of tbis with that of a chimpanzee; of tbis with that of a 

 gorilla, and so on of a Hylohates, Semnopitliecus, Gynocephalua, Ger- 



* Flower "On the Anatomy of Pitliecla Manachtis,'' " Proceedings of the 

 Zoological Society," 18(J2. 



t " Man's Place in Nature," p. 102, 



