848 METABOLISM. 



III. METABOLISM WITH VARIOUS FOODS. 



For carnivora, as above stated, meat as poor as possible in fat may 

 be a complete and sufficient food. As the proteins moreover take a special 

 place among the organic nutritive bodies by the quantity of nitrogen they 

 contain, it is proper that we first describe the metabolism with an exclu- 

 sively meat diet. 



Metabolism with food rich in proteins, or feeding only with meat as 

 poor in fat as possible. 



By an increased supply of proteins the catabolism and the elimination 

 of nitrogen is increased, and this in proportion to the supply of proteins. 



If a certain quantity of meat has daily been given to carnivora as 

 food and the quantity is suddenly increased, an augmented catabolism 

 of proteins, or an increase in the quantity of nitrogen eliminated, is the 

 result. If the animal is daily fed for a certain time with larger quantities 

 of the same meat, a part of the proteins accumulates in the body, but 

 this part decreases from day to day, while there is a corresponding daily 

 increase in the elimination of nitrogen. In this way a nitrogeneous 

 equilibrium is established ; that is, the total quantity of nitrogen eliminated 

 is equal to the quantity of nitrogen in the absorbed proteins or meat. 

 If, on the contrary; an animal which is in nitrogenous equilibrium, hav- 

 ing been fed on large quantities of meat, is suddenly given a small 

 quantity of meat per day, then it uses up its own body proteins, the 

 amount decreasing from day to day. The elimination of nitrogen and 

 the catabolism of proteins decrease constantly, and the animal may in 

 this case also pass into nitrogeneous equilibrium, or almost into this 

 condition. These relations are illustrated by the following table (Vorr) l : 



Grams of Meat in the Food per Day. 



Before the Test. During the Test. 



1 500 1500 



2 150Q 1000 



Grams of Flesh Metabolized in Body per Day. 



1222 1310 1390 1410 1440 1450 1500 

 1153 1086 1088 1080 1027 



In the first case (1) the metabolism of meat before the beginning of 

 the actual experiment on feeding with 500 grams of meat was 447 grams, 

 and it increased considerably on the first day of the experiment, after 

 feeding with 1500 grams of meat. In the second case (2), in which the 

 animal was previously in nitrogenous equilibrium with 1500 grams of meat, 

 the metabolism of flesh on the first day of the experiment, with only 

 3000 grams meat, decreased considerably, and on the fifth day an almost 



1 Hermann's Handbuch, 6, Part I, 110. 



