TRANSMUTABLE. 201 



both fauna and flora will become more and more 

 impoverished. Then, if he gets within the limits 

 of the antarctic fauna, he will again tind it re- 

 sembling that from which he started. 



Now surely cause and effect are pretty clearly 

 shewn in this sketch, which may represent a 

 general view of the fauna of the world. Wher- 

 ever there is plenty of food, there is the greatest 

 abundance of animal life, each creature being 

 adapted to its position in the scale of nature, 

 and wisely so to the circumstances of its ex- 

 istence. 



"There is only one way," says Agassiz, "to 

 account for the distribution of animals as we 

 find them, namely, to suppose that they are 

 autochthonal, that is to say, that they originated 

 like plants, on the soil where they are found. 



In order to explain the particular distribution 

 of many animals, we are even led to admit 

 that they must have been created at several 

 points of the same time; an inference which we 

 must make from the distribution of aquatic 

 animals, especially that of fishes. If we examine 

 the fishes of the different rivers of the United 

 States, peculiar species will be found in each 

 basin, associated with others that are common 

 to several basins. Thus, the Delaware River 

 contains species not found in the Hudson; but 

 on the other hand, the pickerel is found in both. 

 Now if all animals originated at one point, 

 and from a single stock, [as they did, according 

 to Darwin's theory,] the pickerel must have 



