METABOLISM 167 



substance. Death, however, occurs a little later than in 

 complete starvation. 



4. Lack of proteids. If proteids are excluded from the 

 food, while sufficient water, salts, carbohydrates, and fats 

 are given, the body loses its proteids, and since the fats and 

 carbohydrates cannot shield it against the loss, death by 

 starvation results. The daily loss of proteid is, however, 

 slightly less than in absolute hunger, and hence death occurs 

 somewhat later and without the previous increase in nitrogen 

 excretion. 



Notwithstanding the loss of body proteids, the body can 

 lay up fat if the food contains sufficient quantities of fats and 

 carbohydrates. 



Even the taking up of gelatin cannot prevent the loss of 

 body proteids. But the loss of body proteid is less if 

 gelatin is eaten than if nothing but fats and carbohydrates 

 are taken. Proteoses, however, are able to replace all the 

 proteids used in the body. 



5. Lack of fats and carbohydrates in the food while suffi- 

 cient proteids are fed. Fats and carbohydrates can be com- 

 pletely replaced by proteids, at least in the carnivorous 

 animals. For example, by feeding upon lean meat, which 

 is nearly a pure proteid diet, a dog can maintain life. But 

 it is not possible to feed man for a long time exclusively 

 with proteid, as he cannot digest the necessary amount of 

 meat. 



6. If all the necessary foods are given but in insufficient 

 amounts, two cases are possible, (i) The quantity is abso- 

 lutely insufficient. The body now continually uses some of 

 its own constituents, hence death by starvation must finally 

 set in, but at a much later time than in absolute starvation. 

 (2) The quantity of food given is only relatively insufficient 

 to maintain the body at the beginning of starvation. In this 

 case, the body loses some of its substance until the amount 

 used and the amount taken are equal. Then the body 

 maintains itself. Hence the body emaciates, but death does 

 not result. 



