232 DOMESTICATED ANIMALS 



much man may interfere with the course of nature, he is not 

 Hkely to sweep any of their multitudinous kinds from the 

 earth, though experience clearly shows that by the methods 

 above mentioned they may be greatly reduced. 



It is among the vertebrate forms alone that we hnd 

 animals which by their characteristics of body or of mind 

 are well fitted to have an economic or social value. There 

 alone are the qualities of flesh or of the external covering 

 such as to make them in a high measure valuable, and the 

 instincts of a nature to fit them for association in man's 

 work. Even among these back-boned animals we find that 

 the lower groups — the fishes, the amphibians, and the rep- 

 tiles — promise little in the way of gains as compared with 

 the higher groups, the birds and mammals ; yet even among 

 these inferior creatures we find certain forms which give 

 promise of improvement under the care of man. Some of 

 the fishes readily learn to come to any one from whom they 

 may expect food, and they indicate in other ways that they 

 are capable of a certain intellectual advance. The frogs and 

 toads readily learn to recognize a master. Several of the 

 larger members of the first-named forms could advanta- 

 geously be bred so as to be very useful as food. The com- 

 mon hop toad of our gardens is an admirable helper in 

 restraining the excessive development of certain slugs and 

 insects. The tortoises and turtles contain a number of spe- 

 cies which are edible, and many of the forms invite the 

 breeder's care. It is, however, when we ascend in the type 

 of vertebrates to the level of the birds that we find the 

 great array of creatures which are worth considering as 

 members of our civilization. 



Nearly all the birds except those of prey and those which 



