CLASS MAMMALS. 



347 



descriptive word, and the using of these ideas to reach an 

 equally abstract conclusion, they doubtless do not reason. 

 But there is probably no sharp distinction, even in the 

 human mind, between reflex actions, habits, instincts, the 

 utilization of memory and experience in the presence of 

 concrete situations, and pure abstract reasoning. It is 

 doubly difficult to make these distinctions in other 

 animals. 



They have some power of imitation, and while it is not 

 so great as that of man, it nevertheless is an important 

 feature in their behavior. The instinct of imitation 

 makes for quicker and safer education. 



FIG. 146. Diagram of stomach of dog (A) and rat (B). After Wiedersheim 



342. Relations to Nature. The mammals are practically 

 cosmopolitan. The whales, the seals and the sea-cows live 

 in the ocean. The moles and some of the rodents burrow 

 in the ground ; the bats fly quite as well as the birds ; many 

 live in trees, as the sloths and monkeys; and the great 

 majority live on the solid ground. There are some 3,000 

 species. They vary in size from mice to whales. They 

 use all possible kinds of food, and they are closely adjusted 

 in many ways to the nature of their food. These adjust- 



