462 ZOOLOGY 



valuable allies in the struggle for existence. Doubtless they were 

 also his worst enemies in his earlier history. They furnish him 

 meat, milk, clothing, labor, transportation, sport, and compan- 

 ionship. They have always furnished his favorite game when 

 he was not engaged in hunting other men. His domesticated 

 animals are chiefly from this class. In most cases the beginnings 

 of domestication go back to our earliest records and we can 

 only guess which of the species of wild animals he began with. 

 In these cases he has bred and selected them in so many differ- 

 ent ways that scores of distinct varieties are now scattered over 

 the face of the earth. Now that we are coming to understand 

 more of the method of transmitting many of the unit characters 

 (see 493) we shall be able to recombine desirable qualities 

 more systematically, and doubtless new and desirable breeds 

 will arise still more rapidly. 



Man has almost destroyed those fierce mammals that were 

 his terror at the beginning. They are all but extinct or have 

 migrated to the jungles of the tropics. There are, however, a 

 number of smaller ones that he has not been able to control. 

 The cat family is very much less a menace to human interests 

 now than the rodents. Most of these are pests. Rats and mice 

 are the most hurtful. They attack all sorts of vegetable matter 

 both in the fields and in storage. Rats attack poultry. They 

 gnaw and nest in all sorts of manufactured materials. There 

 is no doubt that they damage hundreds of millions of dollars 

 worth of materials in the United States every year. 



Rabbits in some parts of the world are scarcely less injurious. 

 They attack all kinds of tender growths, and in winter may eat 

 the bark fnzfm young trees as high as they can reach. These 

 small rodents multiply rapidly and have become notorious pests, 

 especially when introduced into new regions where their natural 

 enemies were not found. Historic instances are, rabbits in 

 Australia, mongoose in Jamaica and the Bermudas, and the 

 rat into our own country. 



It is not always easy to classify forms as helpful or hurtful. 

 Forms like wolves, coyotes, foxes, mink and weasels undoubtedly 

 attack the poultry, sheep and the larger mammals that we culti- 

 vate, and should be killed. In eighteen months in 1912 and 1913 



