BIRDS AND MAMMALS 353 



Birds as Food. — Birds, both wild and domesticated, form part 

 of our food supply. But our wild game birds are disappearing so 

 fast that we should not consider them as a source of food. Our 

 domestic fowls, turkeys, ducks, etc., form an important food 

 supply, and poultry farms give lucrative employment to many 

 people. Eggs of domesticated birds are of great importance as 

 food, and egg albimiin is used for other purposes, — clarifying 

 sugars, coating photographic papers, etc. 



Mammals as Food. — When we consider the amount of wealth 

 invested in cattle and other domesticated mammals bred and used 

 for food in the United States, we see the great economic importance 

 of this class. In 1925, considerably more than $1,000,000,000 

 worth of fresh meat was killed in the United States. The United 

 States, Argentina, and Australia are the greatest producers of 

 cattle. In this country many hogs are raised for food. Their 

 meat is used fresh, salted, smoked as ham and bacon, and pickled. 

 Sheep, which are raised in great quantities in Australia, Argentina, 

 Russia, Uruguay, and this country, are one of the world's greatest 

 meat supplies. 



Goats, deer, many larger game animals, seals, walruses, etc., 

 are available as food for people in certain parts of the earth. 



Domesticated Animals. — The domestication of the dog, of the 

 cow, of the sheep, and especially of the horse, mark epochs in the 

 advance of civilization. Beasts of burden are used the world over : 

 horses almost everywhere ; certain cattle, as the water buffalo, in 

 tropical Malaysia; camels, goats, and the llama in some other 

 countries. 



Man's wealth in many parts of the world is estimated in terms 

 of his cattle or his herds of sheep. So many products come from 

 these sources that a long list might be given, such as meats, milk, 

 butter, cheese, used as food ; wool or other body coverings, 

 leather, skins, and hides. Great industries are directly dependent 

 upon our domesticated animals, as the tanning of hides, the making 

 of shoes, the manufacture of woolen cloth, and many others. 

 The total value of all live stock on American farms in the year 

 1924 is estimated at the stupendous figure of almost $5,000,000,000. 



Uses of Animal Fibers. — Silk goods are manufactured from 

 raw silk, which is a fiber produced by the silkworm, the caterpillar 



