729 



praecentalis (the fourth and (he sixth field) of the Chimpanzee about 

 two thirds of that in Man, the area striata about equal to that of 

 Man, it must be assumed, according to these determinations, that the 

 absolute number of the nerve cells in the cerebral cortex of Man 

 is much smaller than in the Chimpanzee; greatest is the value of 

 the ratio in the area striata (7, against 6 in the regio praecentralis). 

 The human brain being, however, certainl}' more complicated func- 

 tionally, (which is generally called highly developed), it would appear 

 that not the number of neurones, but the multiplication of the 

 contiguities of their dendritic processes, which principally constitute 

 the interstitium, corresponds to more complicated (higher) fiinctions. 



besonderer Beriicksichligung anthropologischer Fiagen. Gesellsch. Deutscher Natur- 

 forscher und Aerzte. Verhandlungen 1913. Leipzig 1913, p 9, 22 and 25. 



The brain weight of the examined chimpanzee amounted only to 295 grams ; 

 the average in full-grown state may be estimated at about 4(J0 grams. The ratio of 

 the surface of the cortex to that of Man may, therefoi-e, become somewhat more 

 favourable. With greater brain v/eight the density of cells in the cortex of the 

 chimpanzee would have become proportionally less, hence the number of cells 

 would have remained the same. The cortex of Man is, indeed, somewhat thicker, 

 in consequence of which the actual values of the ratio must be proportionately 

 smaller than those calculated. 



