OF TOUCH. 63 



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 a great length to take 

 prey, like that of the chameleon, toad, and frog. In fishes, 

 it is usually cartilaginous, as in birds, generally adherent, and 

 its surface is frequently covered with teeth. 



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

 cartilaginous tongue, the taste must be very obtuse, especial- 

 ly 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 theii 

 readily swallowing artificial bait. It is probable that they 

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

 than by taste or smell. 



116. Some of the inferior animals select their food with 

 no little discernment. Thus, flies will select the sugary 

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

 for example, are particularly dainty in the choice of their 

 food. 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, this 

 sense, like others, may be greatly improved by exercise ; 

 and it is even 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 



