AMERICAN INSTITUTE. 473 



All the excess of blood produced is converted into cellular and 

 muscular tissues, and the animal becomes fleshy and plump. 



A stall-fed animal eats, and reposes for digestion. It devours 

 in the shape of nitrogenized compounds far more food than is 

 required for re-production or the supply of waste alone. Tliis 

 overplus is converted into carbon, and thus thrown off at the rate 

 of five or six pounds in 24 hours. The animal eats, therefore, 

 not merely to add to the weight of its body, but to supply the 

 carbon which is wasted by respiration. The question will now 

 be asked, how the respiration is fed, and what part of the food 

 supplies the waste caused by it 7 In carnivorous animals, it is 

 the fat of their food from which the carbon given off by their 

 lungs is derived. When the fat fails in quantity, the lean part 

 of the flesh they eat is decomposed for the purpose of supplying 

 carbon to their lungs. If we starve an animal for a time, he feeds 

 from the fat first, and then upon his body. The fat first disappears 

 with his heart, and afterwards the muscular part is attacked. 



In herbivorous animals, it is the starch, gum and sugar of the 

 food which supply the carbon for respiration, when the food does 

 not contain a sufficient quantity of these compounds, the oil first, 

 and then the gluten, ai-e decomposed, and made to yield their 

 carbon to the lungs. 



Man, the dog and pig eat indifferently both animal and vege- 

 table food; the carbon of respiration in these cases may be derived 

 partly from the fat and partly from the starch and sugar which 

 they eat, according as they are chiefly supported by the one or by 

 the other kind of food. 



. The flesh of wild animals is devoid of fat; while that of stall- 

 fed animals is covered with that substance. A pig, when fed 

 with highly nitrogenized food, becomes full of flesh; when fed 

 with potatoes, containing starch, it acquires little flesh, but a 

 thick layer of fat. The milk of a cow when stall-fed is very 

 rich in butter, but in the pasture is found to contain more caseine 

 and less butter and sugar of milk. In the human female, beer 

 and fai-inaceous diet increase the proportion of butter in the milk; 

 an animal diet yields less milk, but is richer in caseine. A full- 

 grown woman requires to be kept in condition, as far as the loss 

 of nitrogen is concerned, sufficient food to restore three and a 

 quarter ounces of dry fibrin daily, and to supply this she must 

 eat 32 ounces of wheat flour; or 47 ounces of wheat bread; or 16 

 ounces of fresh beef or mutton; or 14 ounces of peas or bean 

 meal; or 6 ounces of cheese. And if she lives entii-ely upon 



