SUMMARY OF STRUCTURES 701 



or the orang-outang in this regard; so much so that the difference thus 

 established may require explanation. From the known behavior of Trog- 

 lodytes niger, based on Professor Kohler's studies, the chimpanzee seems 

 endowed with a slightly wider range of neokinetic activity than either of the 

 other great apes. This conclusion might imply a higher degree of intelligence 

 on the part of the chimpanzee, and consequently place the animal nearer to 

 man in the primate series. The inference, however, is not so convincing when 

 the physical limitations of gorilla and orang are taken into account. The 

 great size of the former and its natural ineptitudes for satisfactory arboreal 

 and terrestrial living to some extent at least restrict the range of its adapt- 

 ability as compared to the smaller, better proportioned, somewhat more 

 active chimpanzee. 



The case of the orang is seemingly more difficult to establish, for in 

 general size and body weight, it is more chimpanzee-like. Its physical handi- 

 caps, therefore, are not so apparent as those of the gorilla; yet on closer 

 inspection, the underlying reason for its restriction in the acquisition of 

 skilled acts may be discerned. The excessive length of Its powerful arm, while 

 admirably adapted to the purposes of arboreal life, seriously limits its use- 

 fulness for many other purposes. Thus, although the chimpanzee in its 

 pyramidal system gives evidence of greater volitional control than either the 

 orang or the gorilla, this difference may but express certain superior physical 

 qualities of one form over its closely allied congeners. From this point of 

 view, the conclusion that, because of "its greater pyramidal coefficient, the 

 chimpanzee possesses higher intelligence than the orang or the gorilla, seems 

 somewhat doubtful. The differentiation of the forelimb in all three of these 

 forms is about on a par, and the manual development can scarcely be said to 

 give advantages in one or the other. In all three of them the great length of 

 arm cannot be other than a restricting influence in the more plastic and useful 

 adaptation of the hand. Furthermore, the dcfrciencics in the feet of all of 



