METABOLISM AND FOOD 63 



fiuences which are shown by the animal. The 

 animal organism, therefore, breaks up the greater 

 part of the surplus proteins and uses them in place of 

 other material for the production of heat, work, or 

 the formation of fat. This last serves then as a 

 reserve which can be drawn upon in times of in- 

 sufficient food supply, and it does not to any extent 

 impair the capabilities of the animal. 



It has been proved that a large excess of protein 

 given to an adult animal causes respiration to be 

 more rapid and the supply of blood to the skin to 

 increase. Sometimes also the body temperature 

 rises. All these symptoms indicate increased meta- 

 bolism of material and of energy and lead to the 

 decomposition of more protein. This may, in fact, 

 go so far that the body fat is also included in the 

 increased decomposition. 



Animals whose limit of growth is not yet 

 reached behave quite differently with regard to 

 the greater part of the excess of the food pro- 

 teins. They utilise them in the body for development 

 of the organs without the effects noted above being 

 observed, as is the case with adult animals. 



For example, full-grown sheep retain as a rule 

 10 gr., at most 15 gr., of protein daily in the body, 

 most of this, if not the whole, going to form wool. 

 Lambs, on the other hand, in spite of the 

 smaller body weight, are able to store 40-50 gr. 

 daily. Investigations with sucking calves have 



