METABOLISM DUEING A FLESH DIET. 485 



There is a very important difference according as the animals before 

 inanition have been fed freely on flesh and fat, or as they have 

 merely had a subsistence diet. Well-fed animals lose weight much 

 more rapidly during the first few days than on the later days. v. Voit 

 thinks that the albumin derived from the excess of food occurs 

 in a state of loose combination in the body as "circulating" or 

 "storage-albumin," so that during hunger, it must decompose more 

 readily and to a greater extent than the "organ-albumin" which 

 forms an integral part of the tissues (p. 477). Further, in fat indi- 

 viduals, the decomposition of fat is much greater than in slender 

 persons. 



238. Metabolism during a purely Flesh Diet- 

 Albumin or Gelatin. 



A man is not able to maintain his metabolism in equilibrium on 

 a purely flesh diet ; if he were compelled to live on such a diet, he 

 would succumb. The reason is obvious. In beef, the proportion of 

 nitrogenous to non-nitrogenous elementary constituents of food is 1:1 '7 

 (p. 480). A healthy person excretes 280 grammes of carbon, in the 

 form of C0 2 , in the expired air and in the urine and faeces. If a man 

 is to obtain 280 grammes C from a flesh diet he must consume 

 digest and assimilate more than 2 kilos, of beef in 24 hours. But 

 our digestive organs are unequal to this task for any length of time. 

 The person is soon obliged to take less beef, which would necessitate 

 the using of his own tissues, at first the fatty parts and afterwards 

 the proteid substances. 



A Carnivorous animal (dog) whose digestive apparatus, being specially adapted 

 for the digestion of flesh, has a short intestine, and powerfully active digestive 

 fluids, can only maintain its metabolism in a state of equilibrium when fed on a 

 flesh diet free from fat, provided its body is already well supplied with fat, and 

 is muscular. It consumes -& to -^V P ar * of the weight of its body in flesh, so that 

 the excretion of urea increases enormously. If it eats a larger amount, it may 

 " put on flesh," when, of course, it requires to eat more to maintain itself in this 

 condition, until the limit of its digestive activity is reached. If a well-nourished 

 dog is fed on less than -^ to ^V f its body- weight of flesh, it uses part of its 

 own fat and muscle, gradually diminishes in weight, and ultimately succumbs. 

 Poorly fed non-muscular dogs are unable from the very beginning to maintain 

 their metabolism in equilibrium for any length of time on a purely flesh diet, as 

 they must eat so large a quantity of flesh, that their digestive organs cannot digest 

 it. The herbivora cannot live upon flesh food, as their digestive apparatus is 

 adapted solely for the digestion of vegetable food. 



Exactly the same result occurs with other forms of proteids, as 

 with flesh. It has been proved that gelatin may to a certain extent 

 replace proteids in the food, in the proportion of 2 of gelatin to 1 of 



