18 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



food was reduced to 67 per cent of the normal needs and the body- 

 weight fell 11 per cent. As a result of these experiments with rab- 

 bits, it appeared perfectly possible to reduce the diet considerably 

 with almost inappreciable alteration in the total oxygen consumption. 

 Since the curtailment in diet produced only slow changes in the body- 

 weight and since, in the absence of evidence as to the activity of 

 the animal under observation, it must be assumed that the activity 

 was relatively constant, it follows that the lowered food intake was 

 without appreciable effect upon the metabolism. 



In experiments with dogs, Pashutin found that when the diet was 

 reduced to 75 per cent of the normal requirement, neither the oxygen 

 consumption nor carbon-dioxide production was appreciably altered. 

 On the other hand, the period of observation was so short (apparently 

 not far from 2 weeks) that the diet was not sufficiently low to alter 

 materially the body- weight. 



A dog, with which observations were begun January 15, was fed for 

 a month with 500 grams of horse flesh daily. Its weight in the middle 

 of February was 6,098 grams. The food was then reduced and 75 per 

 cent of the normal diet given for 19 days, 65 per cent for 29 days, 

 and 55 per cent for 7 days. During the last period the animal fell 

 to a weight 10.6 per cent below the initial weight. He was subse- 

 quently fed with 500 grams of meat for 24 days; a second undernutrition 

 period of 33 days with 55 per cent of food followed. Under these con- 

 ditions it was found that when 75 per cent of food was given, the oxy- 

 gen consumption and carbon-dioxide excretion fell to about 88 per cent 

 of the normal ; it was not until the food was reduced to 55 per cent of 

 the normal diet that the gaseous metabolism fell to approximately 75 

 per cent. In the realimentation period the gaseous metabolism did 

 not return to the normal amount. In the second undernutrition 

 period the oxygen fell to 71 per cent and the carbon dioxide to 66 

 per cent of the normal excretion. During the second realimentation 

 period of 23 days with 500 grams of meat the animal gained in weight 

 so that he was 26 per cent above normal. Even under these conditions 

 the oxygen consumption was only 79 per cent of normal and the 

 carbon-dioxide production 74 per cent. With this dog, therefore, it is 

 clear that the reduction in diet was accompanied by a distinct fall in 

 the respiratory exchange, a fall that was not compensated by reali- 

 mentation, even when the body-weight increased to 26 per cent above 

 normal. 



A second dog was brought into equilibrium at a body-weight of 6,221 

 grams by feeding with an abundance (617 grams) of horse flesh. The 

 food was then reduced to 63.2 per cent of his normal amount. This 

 period of undernutrition continued 23 days. The dog was next fed for 

 28 days with approximately 3 per cent above the normal amount of food. 

 A second undernutrition period of 22 days followed, in which the food 



