OF TOUCH. 39 



at the edges. In the parrots, it is thick and fleshy ; 

 or it is even barbed at its point as in the woodpeckers. 

 In some reptiles, the crocodile, for example, the tongue 

 is adherent ; in others, on the contrary, it is capable of 

 extensive motion, and serves as an organ of touch, as in the 

 serpents, or it may be thrust out to take prey, like that of 

 the chameleon. In fishes it is usually cartilaginous as in 

 birds, generally adherent, and its surface is frequently cov- 

 ered with teeth. Some of the inferior animals select their 

 food with no little discernment. Thus, flies always select 

 the sugary portions of bodies. Some of the mollusks, as the 

 snails for example, are particularly dainty in the choice of 

 their food. 



115. It is to be presumed that in animals which have a 

 cartilaginous tongue the taste must be very obtuse, espe- 

 cially in those which, like most fishes and many granivorous 

 birds, swallow their prey without mastication. In fishes, 

 especially, the taste is very imperfect, as is proved by their 

 readily swallowing artificial bait. It is probable that they 

 are guided in the choice of their prey by sight, rather 

 than by taste or smell. 



116. In general, the taste is but imperfectly developed 

 except in the mammals, and they are the only animals 

 which enjoy the flavor of their food. With man, the culti- 

 vation of this sense becomes a matter of study ; and it is 

 capable of being brought to a high degree of delicacy. 



5. Of Touch. 



117. The sense of TOUCH is merely a peculiar manifesta- 

 tion of the general sensibility, seated in the skin, and 

 dependent upon the nerves of sensation which expand over 

 the surface of the body. By the aid of this general sensi- 

 bility, we learn whether a body is hot or cold, wet or dry. 

 We may also, by simple contact, gain an idea, to a certain 



