212 THE PRINCIPLES OP AGRICULTURE 



set even to these, the red globules being 

 mainly carriers of oxygen, while the white also 

 have restricted functions. 



2. The Food of Animals 

 2a. Kind of food 



367. Food may be either vegetable or ani- 

 mal. Many animals, as horses, cattle and 

 sheep, live on vegetables, or are herbivorous ; 

 while others, like foxes and wolves, eat animal 

 food only, or are carnivorous. The food of 

 the herbivorous animal has its nutritive prin- 

 ciples in a less concentrated condition, and the 

 herbivora are accordingly supplied with more 

 capacious digestive organs. The same holds 

 true of grain-feeders and grass-feeders among 

 the herbivora. The grain -fed horse has much 

 smaller stomach and intestines than the grass- 

 fed ox, and the well-fed domestic rabbit has a 

 much more spacious alimentary canal than his 

 wild ancestor. 



368. Artificial selection and forcing of meat- 

 producing animals has a similar effect. The 

 scrub ox, Texas steer and buffalo have light ab- 

 dominal contents, while the pampered short-horn, 

 Hereford, or black-polled ox has them heavy 

 and bulky. In the carnivora they are still more 



