THE ANIMAL SERIES 393 



birds are the game birds which are still in existence in the 

 wild state. Some of these are the wild geese, ducks, and 

 turkeys. The quail, a game bird, does not migrate, but 

 adapts itself to its surroundings the whole year round, 

 living upon whatever it is able to find, eating some grain 

 but mostly wild berries, seeds of wild plants, and insects. 

 Wild geese and ducks migrate from north to south with 

 the change of seasons. They fly in flocks, usually in 

 the form of a V, the leader of the flock is at the apex of 

 theV. 



272. Mammals. Mammals compose a group of ani- 

 mals which are the most highly developed of all. The egg 

 produced by the female is microscopic in size and is fer- 

 tilized within the body of the mother, and there grows into 

 the young animal with all the parts of an adult. After 

 birth the young are nourished for a time by milk secreted 

 by the mammary glands of the mother. Examples of 

 mammals are the elephant, lion, mink, cat, dog, horse, cow, 

 monkey, and man. A number of the mammals are plant- 

 eating or live entirely on plants. Some of the animals 

 which live upon plants serve as food for those which live 

 upon flesh. Those animals which live on other animals 

 acquired the habit of eating flesh because it was more easy 

 to get sufficient food by that method than to gather their 

 nourishment from plants. Some of the flesh-eating animals 

 are those of the cat family. There are some animals 

 which eat both plants and flesh. The domesticated dog 

 and cat have acquired the habit of eating both plant and 

 animal food. The bear also lives upon plant and animal 

 food. The opossum, a native animal of North America, 

 lives upon both plant and animal food. 



Nearly all of the domesticated animals which man now 

 possesses originated from animals of like kind living in 



