58 PRINCIPLES OF ANIMAL NUTRITION. 
From the smaller gain in Period III, the conclusion is drawn 
that the asparagin has a lower nutritive value than the proteids. 
In this period the percentage digestibility of the crude fiber 
of the ration was found to be 64.88, as compared with 43.96 and 
33.33 in the second and fourth periods, an effect corresponding to 
that observed by Kellner, and which Tryniszewsky also ascribes 
to an increase in the micro-organisms of the digestive tract. 
The results of the experiments which have been cited are, of 
course, valid, in the first instance, only for the particular non-~ 
proteids experimented with. If, however, the above interpretation 
of the results is correct, it is to be anticipated that other soluble 
nitrogenous substances in the food will be found to produce similar 
effects. If this anticipation proves to be correct, then we shall 
reach the following conclusions regarding the amides and similar 
bodies in feeding-stuffs. 
1. That they do not serve as sources of proteids. 
2. That in rations very poor in protein they have, in the her- 
bivora, an indirect effect in protecting part of the food protein 
from fermentation in the digestive tract. 
3. That in carnivora, and in herbivora on normal rations, they 
probably have no effect on the production of nitrogenous tissue. 
