THE SOURCE OF MUSCULAR POWER. 815 



One result of these researches has been to demonstrate that the 

 consumption of 'proteine in the body is determined by the amount of it 

 present in the food. If the food contains but little proteine, but little 

 is oxidized in the body ; if more be added, the consumption of it in 

 the vital processes promptly increases, and within at the most three or 

 four days comes into equilibrium with the supply, or very nearly so.* 



Another important point is the distinction, first introduced by Voit, 

 between what he calls circulatory and organized proteine. He has shown, 

 by experiments which it would take too much space to describe, that the 

 proteine of the body exists in two states : first, as organized proteine, 

 which is comparatively stable ; and, second, circulatory proteine, which 

 exists in much smaller amount than the other, and undergoes a much 

 more rapid decomposition in the body. The first effect of albuminoids 

 in the food is to increase the amount of this circulatory proteine and 

 the rapidity of its decomposition, and it is in this way that the con- 

 sumption of proteine in the body is, as has just been stated, determined 

 by the supply of albuminoids in the food. The production of organ- 

 ized proteine, which Voit supposes to constitute the muscular tissue, 

 is, on the contrary, much less rapid, it being slowly formed from the 

 circulatory proteine under proper conditions. 



Some authorities dispute the correctness of the names circulatory 

 and organized proteine, but there is no dispute as to the fact, shown by 

 his experiments, that most of the proteine of the body exists in a com- 

 paratively stable form, while a small portion, dependent in amount 

 upon the supply in the food, is being continually and rapidly oxidized 

 and furnishes most of the nitrogen eliminated through the kidneys. 

 We might compare the stock of circulatory albuminoids in the body 

 to a mass of water contained in a vessel with a small aperture in the 

 bottom. If there is no supply, it quickly runs out. If a small stream 

 of water be let in at the top, a small supply of water may be main- 

 tained in the vessel. If a larger stream be admitted, the depth of 

 water in the vessel will at once begin to increase, but at the same time 

 the pressure on the bottom, and consequently the rapidity of the out- 

 ward flow through the aperture, increases, and outflow and inflow soon 

 come into equilibrium. If the supply be diminished, the level of the 

 water sinks till the hydrostatic pressure causes the outflow to again 

 equal the inflow. 



Voit's results have been abundantly confirmed by other observers 

 in experiments on various animals, including man, and must be re- 

 garded as fully established, whatever view we may take of the inter- 

 pretation put upon them by their author. In Professor Flint's book, 

 however, we fail to find any reference to these discoveries, though 

 they have, as we shall see, a most important bearing on his own experi- 

 ments. He does, indeed, mention the similar but less complete results 



* Voit's experiments were made on dogs. With herbivorous animals the same law 

 holds, but the change is not so rapid. 



