i8o 



THE HUMAN SPECIES 



superior fossa and the upper part of the nasal septum ; this 



olfactory region in man is of a red colour, in horses and cattle 



yellowish, in sheep yellow-ochre colour, in goats black, in pigs 



brown, and in cats and dogs grey. 



The olfactory nerve-endings consist, in Vertebrates as well 



as Invertebrates, of the so-called olfactory rod-cells (Fig. 90). 

 The shape of the external nose in man has been acquired 



by a process of evolution. 



Among apes the Hoolock-Gibbon is 

 remarkable for its crooked nose, the nosed 

 ape (Nasalis larvatus) has a long pro- 

 tuberant nose (Figs. 91 and 92), but the 

 latter is merely a soft snout-like structure. 

 The human nose, on the other hand, owes 

 its prominence to the height of the lamina 

 perpendicularis of the ethmoid bone and 

 the vomer, as well as to the extension 

 backwards of the lateral portions of the 

 superior maxilla. 



In the gorilla, a near ally of man, the 

 ridge of the nose is only indicated by a 

 slight protuberance, and the alae nasi are 

 very well marked, yet the nose of the 

 gorilla projects far more than that of the 

 chimpanzee and orang-outang, and ap- 



FIG. 90. Olfactory nerve- proaches rather to the type of many West 



cells, highly magni- A ,- . 



fied. (Thome, Zool- African negroes. 



ogle.) a, epithelial * Sense of Taste. It may be re- 

 cells, divided below . 

 into two processes; garded as highly probable that even the 



b nerve to cell ; c i nver tebrates are led to select their food 



olfactory-cell with 



nerve-cell ; and d, by taste, although we are still quite in the 



descending fibril. ,. , r ,,. 



dark as to the organs which serve tor this 

 sensation, and can at most only assume that they are some- 

 where in the neighbourhood of the oral aperture. This is not 

 very surprising, since even in the lower Vertebrates the " taste 

 organs " cannot be located with any certainty, though we might 

 expect them to lie in the area supplied by the glosso-pharyngeal 

 nerve, in the tongue and gullet. When the tongue is absent, 

 as in fishes, taste is most likely derived from the palate and 



