PAET I. 

 THE GENERAL LAWS OF ANIMAL NUTRITION. 



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THE OOMPOSITIOK OF THE ANIMAL BODY. 



§ L PjKOPORTIONS OF THE DiFFEEENT OrGAKS AI^D PaRTS. 



The yitiids circulating in the hlaod and lymph vessels 

 constitute but a small part, at most not more than 7 to 9 per 

 cent., of the live weight, and in old or very fat animals the 

 proportion sinks as low as from 4 to 6 per cent. The 

 digestive fluids and other secretions and fluid excretionsj 

 although they are produced in considerable quantity in the 

 course of twenty-four hours, can hardly be taken into 

 account as constituents of the body, since they are being 

 produced at every instant, are formed more or less directly 

 from the blood, and are partly re-absorbed into it or pass 

 out of the body ; while the blood, on the other hand, al- 

 though continually giving up rnaterial to the tissues and 

 receiving new from the food, remains very constant in its 

 quantity and chemical properties. 



The Solid Tissues.— The fresh bones constitute, ac- 

 cording to the kind, age, and condition of the animal, 6 to 12 

 per cent, of its weight, the muscles and tendons 35 to 48 per 



