. HABITS. 523 



the mother usually indicates the greater or smaller number of 

 the progeny. 



Many Mammalia live a solitary life, and pair only at breeding 

 time ; they are principally such carnivorous animals as find their 

 subsistence by hunting in definite hunting grounds, like the 

 mole in its subterranean passages. Others live united in com- 

 panies, in which the oldest and strongest males frequently under- 

 take the protection and leadership. Most mammals seek their 

 food by day. Some, e.g. the bat, leave their hiding places in the 

 twilight and at night. Most Garni vora and numerous Ungulata 

 also sleep in the daytime. Some Rodentia, Insectivora, and 

 Carnivora fall, during the cold season of the year when food is 

 scarce, into an interrupted (bear, badger, bat) or continuous 

 (dormouse, hedgehog, marmots) winter sleep in their hiding 

 places, which are often carefully protected, or in nests formed in 

 the earth. During this time the temperature is lowered, the 

 respiration is less active, the heart beat is slowed, and they take 

 up no food, but consume the fat masses which were stored up 

 in the autumn. The following animals are known to migrate : 

 the reindeer, the South African antelopes, and the North 

 American buffalo ; the seals, whales, and bats, but more especially 

 the lemmings, which migrate in enormous herds from the nor- 

 thern mountains southwards to the plains, are stopped by no 

 obstacles on their journey, and even cross rivers and arms of the 

 sea. 



The intellectual faculties are more highly developed than in 

 any other class of animals. The Mammalia possess the faculty 

 of discrimination and memory; they form ideas, judgments, 

 and conclusions ; they exhibit affection and love to their bene- 

 factors, dislike, hate, and anger to their enemies ; each individual 

 has a definite character. Further, the intellectual faculties of 

 mammals are capable of being developed and improved, but, 

 except in Homo, to a relatively small extent on account of the 

 absence of articulate speech. The more docile of them have been 

 chosen by man as domestic animals, and in this capacity have 

 played an important and indispensable part in the history of 

 civilisation (dog, horse). Instinct always occupies an important 

 place in their life. It leads many of them to construct 

 spacious passages and ingenious nests above or below the 

 earth, in which they rest and bring up their offspring. Almost 



