32 SPHERE AND FUNDAMENTAL 



it has been developed from a hen's egg, and we know that, 

 should it continue to live, it would infallibly display all the 

 characteristics of the parent bird. Now, if there existed in 

 Nature an adult bird as imperfectly organized as the chicken 

 on the day, or the day before it was hatched, we should 

 assign to it an inferior rank. 



22. In studying the embryonic states of the mollusks or 

 worms, we observe in them points of resemblance to many 

 animals of a lower grade, to which they at length be- 

 come entirely dissimilar. For example, the myriads of 

 minute aquatic animals embraced under the name of Infu- 

 soria, generally very simple in their organization, remind 

 us of the embryonic forms of other animals. We shall have 

 occasion to show that the Infusoria are not to be considered 

 as a distinct class of animals, but that among them are found 

 members of all the lower classes of animals, mollusks, 

 crustaceans, worms, &c. ; and many of them are even found 

 to belong to the Vegetable Kingdom. 



23. Not less striking are the relations that exist between 

 animals and the regions they inhabit. Every animal has its 

 home. Animals of the cold regions are not the same as 

 those of temperate climates ; and these latter, in their turn, 

 differ from those of tropical regions. Certainly, no one will 

 maintain it to be the effect of accident that the monkeys, 

 the most perfect of all brute animals, are found only in hot 

 countries ; or that by chance merely the white bear and 

 reindeer inhabit only cold regions. 



24. Nor is it by chance that most of the largest animals, 

 of every class, the whales, the aquatic birds, the sea-turtles, 

 the crocodiles, dwell in the water rather than on the land. 

 And while the water affords freedom of motion to the largest, 

 it is also the home of the smallest of living beings, allow- 

 ing a degree of liberty to their motion, which they could not 

 enjoy elsewhere. 



