EXCHANGE OF MATERIAL. 457 



nourished body can be kept in its ordinary condition, while a 

 poorly -nourished or diseased organism cannot be made fat. 



The very considerable elimination of nitrogen and the peculiar- 

 ities which it presents in an exclusively meat diet have, together 

 with other circumstances, among which is the unequal behavior of 

 the metabolism of proteids on the first and the following days of 

 starvation, led to the view (Vorr) that all proteids in the body are 

 not decomposed with the same ease. VOTT differentiates the proteids 

 fixed in the tissue-elements, so-called organized proteids, tissue- 

 proteids, from those proteids which circulate with the fluids in the 

 body and its tissues and which are taken up by the living cells of 

 the tissues from the interstial fluids washing them. These circu- 

 lating proteids are, according to VOIT, more easily and quickly 

 destroyed than the tissue-proteids. Although in a fasting animal 

 which has been previously fed with meat an abundant and quickly- 

 decreasing decomposition of proteids takes place, while in the fur- 

 ther course of starvation this proteid metabolism becomes less and 

 more uniform, still this depends upon the fact that the supply of 

 circulating proteids is diminished chiefly in the first days of starva- 

 tion and the tissue-proteids in the last days. 



The tissue-elements constitute an apparatus of a relatively stable 

 nature, which has the power of taking proteids from the fluids 

 washing the tissues and digesting them, while a few proteids, the 

 tissue-proteids, are ordinarily only disorganized to a small extent, 

 about \% daily (Voix). By an increased supply of proteids the 

 activity of the cells and their ability to decompose nutritive pro- 

 teids is also increased to a certain degree. When nitrogenous 

 equilibrium is obtained after increased supply of proteids, it denotes 

 that the decomposing power of the cells for proteids has increased 

 so that the same amount of proteids is metabolized as is supplied 

 to the body. If the proteid metabolism is decreased by the simul- 

 taneous administration of other non-nitrogenized foods (see below), 

 a part of the circulating proteids may have time to become fixed 

 and organized by the tissues, and in this way the mass of the flesh 

 of the body increases. During starvation or with lack of proteids 

 in the food the reverse takes place, for a part of the tissue proteids 

 is converted into circulating proteids which are metabolized, and 

 in this case the flesh of the body decreases. 



