.94 GEOGRAPHICAL DISTRIBUTION. 



which they are the instruments, as was observed 

 by Sparrman of the locusts, are often followed 

 by fertility, and the fearful scourge is replaced 

 by Amalthea's horn. 



2. We are next to consider those migrations 

 that take place periodically, and usually at certain 

 seasons of every year ; the general intention of 

 which appears to be a supply of food, and often 

 a temperature best suited to reproduction. Pro- 

 vidence, in this, taking care that their instincts 

 shall stimulate them to change their quarters, 

 when these two objects can be answered at the 

 same time, and by a single removal. 



In North America, that ferocious and lion-like 

 animal, the Bison? called there the Buffalo, 

 forms regular migrations, in immense herds, from 

 north to south, and from the mountains to the 

 plains, and after a certain period returns back 

 again. Salt-springs, usually called salt-licks or 

 salines, found in a clay, compact enough for 

 potter's clay, are much frequented by these 

 animals, whence they are called Buffalo salt- 

 licks. Dr. Richardson informs me that the 

 periodical movements of these animals are regu- 

 lated almost solely by the pastures : when a fire 

 has spread over the prairies, it is succeeded by a 

 fine growth of tender grass, which they are sure 

 to visit. How the Bison discovers that this has 



1 Bos Americanus. 



