ANIMAL NUTRITION. 101 



may be called, as he strictly is, the omnivorous, or all- 

 eating animal. 



ANIMAL NUTRITION. 



When we examine the structure of the very lowest 

 orders of animal existences, we find, that whatever 

 other parts may be wanting, whether they be eyes, or 

 ears, or nerves, or brain, or organs of locomotion, two 

 parts are always present, to wit, a mouth and a stomach. 

 Without these no animal can exist, for however com- 

 plex the organization, in other respects, may be, nothing 

 can compensate for the organs of nutrition. From the 

 account we have given of the structure of the Hydra, 

 it would appear that nearly every other part usually 

 constituting an animal may be dispensed with, except 

 these ; and that some of the Polypi consist of little or 

 nothing more than a throat and organ of digestion. 



Some animals have several stomachs. Some of the 

 polypi tribes have at least four stomachs, and the Asteria 

 or star-fish a very common inhabitant of our sea shores, 

 has ten distinct digestive organs. 



Fig. 71. 



The mouth of this animal, a, is situated in a depres- 

 sion at the centre of the under surface, and leads into 

 a capacious sack or bag, placed immediately above it, 

 when the animal lies with the mouth downwards which 



What is said of the necessity of a mouth and stomach to each animal 1 

 What is said of the number of stomachs, possessed by some animals 1 

 9* 



