172 REPRODUCTION. 



contained several hundred eggs, which, on heing freed from 

 their envelop, float in the water. As these eggs are innu- 

 merable, it is not astonishing that the Sculpins should occa- 

 sionally swallow some of them with their prey. The eggs, 

 being thus introduced into the stomach of the fish, find con- 

 ditions favorable to their development ; and thus the species 

 is propagated, and at the same time transmitted from one 

 generation of the fish to another. The eggs which are not 

 s-.vallowed are probably lost. 



363. All animals swallow, in the same manner, with their 

 food, and in the water they drink, numerous eggs of such 

 parasites, any one of which, finding in the intestine of the 

 animal favorable conditions, may be hatched. It is probable 

 that each animal affords the proper conditions for some par- 

 ticular species of worm ; and thus we may explain how it is 

 that most animals have parasites peculiar to themselves. 



364. As respects the Infusoria, we also know that most 

 of them, the Rotifera especially, lay eggs. These eggs, 

 which are extremely minute, (some of them only -rs^iny f 

 an inch in diameter,) are scattered every where in great 

 profusion, in water, in the air, in mist, and even in snow. 

 Assiduous observers have not only seen the eggs laid, but 

 moreover, have followed their development, and have seen 

 the young animal forming in the egg, then escaping from it, 

 increasing in size, and, in its turn, laying eggs. They have 

 been able, in some instances, to follow them even to the fifth 

 and sixth generation. 



365. This being the case, it is much more natural to 

 suppose that the Infusoria * are products of like germs, than 



* In this connection, it ought to he remembered that a large proportion 

 of the so-called Infusoria are not independent animals, but immature 

 germs, belonging to different classes of the Animal Kingdom, and that 

 many must be refeired to the Vegetable Kingdom. 



