70 GRAHAM LUSK 



the period. This was because of the saturation of the body tissues with 

 water when taking the bread diet, for when he was given 1800 gm. of 

 meat he passed a great stream of water, losing 300 gm. in body weight in 

 spite of a retention of the protein of meat which would have been the 

 equivalent of an addition to the body of 600 gm. of new "flesh" (vide 

 experiment of Stark, p. 14). 



The authors found that, though gelatin could spare some body protein, 

 it could not entirely prevent its- loss. They state that it is an incomplete 

 (ungeniigendes) foodstuff. 



Results briefly abstracted. 



We hold it for proved that the continued power to maintain movement on 

 the part of a fasting organism is derived from the metabolism of protein. 



The three factors which induce metabolism are "blood, organ and oxygen, 

 and we believe that the metabolism of an organ is brought about by the united 

 action of all three influences. 



The mass of non-nitrogenous and nitrogen-containing tissue, the quantity 

 of blood and blood plasma and the amount of available oxygen, these three fac- 

 tors determine the height of the metabolism. 



If one gives to a fasting dog meat in such quantity that a loss from the 

 dog's body is not prevented, the metabolism rises. The increased quantity of 

 blood plasma increases the metabolism, although the mass of the organs remains 

 the same; the influence of oxygen, on account of the increased food and metab- 

 olism, is greatly reduced. ... As oxygen is present only in limited amount, 

 its action is reduced upon both body protein and body fat; the metabolism of 

 these is in consequence reduced. 



If we increase the food protein and the blood plasma, the metabolism is 

 constantly increased until we reach a point when loss from the body is equal to 

 its repair. This is the moment when the metabolism of the protein parts of the 

 organism has so increased as to acquire all the oxygen available, and the metab- 

 olism of fat ceases. 



If the amount of food be still further increased the metabolism scarcely in- 

 creases, for the available oxygen, through union with metabolic products, 

 has been reduced to a minimum. This is the moment when deposit, increase in 

 mass, excess for reparation, must and can ensue. . . . 



But this process has a limit. As the intake of meat and the mass of the 

 nitrogen-containing tissue increases, the metabolic products also increase. 

 These require more oxygen. But the action of this is so reduced that, in spite 

 of the increased bulk of the plasma and of the organs, a limit to the metabolism 

 is set. As soon as the limit of metabolism is reached the limit of energy pro- 

 duction is also reached. If energy is no longer present and available, it is also 

 no longer possible to increase the metabolism. The animal can no longer eat and 

 refuses food. With a limitation of food intake the volume of blood and plasma 

 falls and the former condition returns. 



This process constitutes an absolute proof that there is no such thing as 

 Luxus consumption of meat in the sense of the hypothesis of Frerichs' and of 

 Schmidt's ; i. e., that an oxidation of food protein in the blood takes place without 

 previous incorporation with the nitrogen-containing parts of the body tissue. 



Sugar reduces the protein metabolism in the organs of the body and reduces 

 the quantity of protein in the food needed for replacement purposes, and pos- 

 sesses these influences even more than fat, probably because it has a greater 



