178 ORGANIC STRUCTURE OF FISH. 



had he not been endowed with the strange fa- 

 culty of extendmg, by blowing himself up^ the 

 multiplied folds of his skin, and of rendering him- 

 self lighter in proportion to the space he stands 

 upon."* 



The strong digestive powers of the dog's stomach, 

 is another instance of the same harmonious agreement. 

 His appetite teaches him to swallow bones, which, 

 though not ground into powder with his teeth, are 

 presently softened and dissolved by the extraordinary 

 power of the gastric juice of his stomach. 



The air-bladder peculiar to fishes, by the dilation 

 or contraction of which they rise or sink at pleasure, 

 enables them to live in an element that would be de- 

 structive to most other animals, but which is their 

 destined habitation. Their organs of sight and hear- 

 ing differ from those of other creatures, but are adapt- 

 ed, in a particular manner, to that medium through 

 which they are obliged to see and hear. Their fins, 

 as artfully contrived for swimming as the wings of 

 birds for flying, display great variety of form, num- 

 ber, situation, and force, according to the habits and 

 wants of their owners. The size and shape of the 

 mouths of fishes would, probably, go far to ascer- 

 tain the kind of prey they feed upon, as there is no j 



* Hunter's translation of St. Pierre's Studies of Nature, 

 vol. i. p. 339. 



