338 PHILOSOPHY OF ZOOLOGY. 



issue follows the completion of the function of reproduction 

 with regularity *. 



Fishes exhibit remarkable differences wath respect to 

 their vivaciousness. Thus, some fishes expire almost the 

 instant they are taken out of the water, as the herring and 

 smelt ; others are capable of surviving hours, and even 

 days, when removed from their native element, as the eel, 

 carp, and some others. It sometimes happens, that viva- 

 cious fishes are conveyed to a distance by birds, and left, 

 without being killed, on rocks or fields. This has given 

 rise to many of the absurd stories which have been told of 

 showers of fishes. Rondeletius observes with propriety, 

 that those fishes in which the gill openings are but imper- 

 fectly covered, expire soonest when taken from the water ; 

 and those fish having branchiae, protected by a gill-hd 

 which shuts close, or by a narrow opening, are most viva- 

 cious. The air soon dries the fine plumes of the gills, and 

 obstructs the process of respiration and of circulation. 



It is seldom that a fish is permitted to die a natural 

 death from old age. During every period of its existence, 

 it is suiTounded by foes ; and when no longer able to exer- 

 cise its wonted watchfulness, or exert its powers of defence, 

 it falls an easy prey to its more powerful adversaries. In 

 a domesticated state, previous to death, the dorsal fins lose 

 the power of maintaining the body in a vertical position, 

 the levity of the belly, and the extraordinary distension of 

 the air bag, reverse the natural }X)sition, so that the back 

 becomes imdermost, and the body floats on the surface. 

 Similar appearances present themselves, when the Avaters 

 are contaminated by noxious mineral or vegetable impreg- 

 nations. 



We have already stated, that fishes naturally reside in 

 the water ; but as this element is found to differ in its con- 



" Annals of Philosophj', Ftbrnary 1S16. 



