214 SYMBWGENES1S 



The "ferments" themselves (to which Spencer alludes) 

 are the products of a very slow and reciprocal co-operative 

 evolution, to which, indeed, they owe their adequacy. Their 

 efficacy and range of power changes pari passu with other 

 important changes in the organism. Hence to argue from 

 their composition as to the requirements of nitrogen by 

 organisms is at best post hoc but not propter hoc argument. 

 In many instances we find the ferment possessed by pathogenic 

 organisms confined in their efiicacy to their peculiar " food," 

 i.e., it can act only on the bodies (or very similar material) of 

 those morbid organisms (hosts) on which they batten, but 

 they cannot produce the same decomposing effects upon other 

 material or upon the tissues of healthy organisms. We may 

 say that the ferments in these instances have become reduced 

 and limited in symbiogenetic efficacy pari passu with the 

 general loss of life-energy and of symbiogenetic status 

 (correspondences) on the part of the degenerate organism. 



Further, in a paper read before the Seventeenth Inter- 

 national Congress of Medicine (Lancet, 6/8/13), Prof. 0. 

 Folin (Harvard) pointed out that urea, the chief nitrogenous 

 waste product, is not an oxidation product of the nitrogenous 

 materials. "The animal body," he says, "is not capable of 

 oxidising the amino groups contained in nitrogenous materials 

 taken as food (which food?), and the urea formation, as I look 

 at it, is perhaps the most important mechanism for preserving 

 the neutrality of the body fluids. If it were not for the urea 

 formation, the body fluids would become loaded with ammonia. 

 The urea represents, therefore, chiefly a metabolism of 

 superfluous nitrogen in the food." (Italics mine.) 



Thus we see how great are the difficulties of the animal 

 body to deal with a surfeit or with what is more than strictly 

 required of nitrogenous food. Moreover, there is a qualita- 

 tive difference ; for some of the amino groups our body cannot 

 oxidise at all, and must store them away as waste matter and 

 try to eliminate them as best it can, though frequently with 

 pathological concomitants. 



