n6 



THE HUMAN SPECIES 



by the gorilla, chimpanzee and orang (see Fig. 62). In the 

 orang and gorilla these sacs are divided into an upper and a 

 lower, the right one being usually larger than the left. What 

 renders the adult gorilla so extraordinarily ugly are the front 

 parts of the two sacs, hanging from throat to chest in the form 

 of large, loose folds of skin. 



Further distinctions between man and the anthropoids are 

 to be found in the tracheae and lungs (see Fig. 64). The two 

 branches of the human tracheae differ but little as to lumen 



FIG. 62. Adult male oran-utan (throat sac). 



FIG. 63. Anterior section of larynx 

 viewed from within. (Thome, 

 Zoologie.) a, epiglottis; cr, 

 cricoid cartilage ; Taep, Tae, 

 Tai, sections of three muscles 

 (shown white in diagram), 

 i, thyroid cartilage ; 2, 

 laryngeal cavity ; 3, upper 

 extremities of same ; 4, liga- 

 mentum glottidis ; 5, vocal 

 cord. 



whereas in the anthropoids the left branch is generally smaller 

 than the right, from which, at a short distance from the trunk, 

 springs a large lateral branch. 



The pulmonary lobes, of which man has three in the right 

 lung and two in the left, in the anthropoids are either more 

 numerous or, as in the orang, are not definitely separated from 

 one another. 1 Wiedersheim's researches reveal the fact that 

 other conditions must have obtained among the progenitors of 

 man than those of the present day. From the fact that the 



1 Ranke, loc. cit., i., 293. 



