394 GENERAL SCIENCE 



the wild state. The dog is supposed to have originated 

 from the wild dog, and the cow from various wild types; a 

 near relative of the cow is the buffalo. Wild cats are still 

 in existence in various parts of the Appalachian Moun- 

 tains. Elephants have been domesticated and are very 

 valuable beasts of burden. The horse is a native of North 

 America. It originated from an animal about the size of 

 a wolf. It had four toes on each front foot and three toes 

 on the hind feet. It gradually acquired the habit of walk- 

 ing on the middle toe of each foot. This caused the bones 

 and hoof of the middle toe to enlarge and the other toes to 

 decrease in size, so that now they cannot be seen except 

 occasionally on some horses when an extra hoof appears. 

 The horses which developed the bones of the front toe 

 were more swift than those which did not, because they 

 had longer legs and thus were able to escape their enemies 

 and keep their kind in existence. The horse finally 

 migrated to the Asiatic continent where it was first 

 domesticated by man, and since that time it has been 

 greatly improved and many types have been produced, 

 varying in size from a pony of a few hundred pounds to 

 the huge draft horse weighing one ton. 



All other domesticated animals which are of economic 

 value have also been greatly improved by the study of 

 biology, which has enabled the farmers to control the 

 types and kinds which they wish to maintain. Cattle 

 have been produced which weigh 2,000 pounds, and some 

 have been produced which are immune from various kinds 

 of diseases. The hog the pork-producing animal 

 has also been greatly improved, so that it grows to weigh 

 several hundred pounds in less than a year; some have 

 been produced which weigh from 600 to 800 pounds after 

 two or three years of special feeding. 



