CHEMICAL DYNAMICS OF ANIMAL NUTRITION 157 



It will be observed from this table that the maximum amount of 

 autolysis occurs in the liver and spleen, the two organs which lose the 

 greatest amount of weight during starvation. This affords a striking 

 confirmation of the suggestion made in the first paper, viz., that the 

 autolytic enzyme has the function of protecting the organism from 

 starvation. 



PART VI 



A THEORY OF NITROGENOUS METABOLISM, DEDUCED FROM THE 

 RESULTS OF THE FOREGOING RESEARCHES 



Attention has already been called to the controversy as to whether 

 the products of tryptic digestion of albumens can be detected in the 

 blood ; it has been claimed, furthermore, that the methods hitherto 

 employed for investigating this problem have not been entirely satis- 

 factory. As it was imperative to arrive at a decisive settlement of 

 this question, if possible, in order to gain a clear view as to the 

 function of the albumens in nutrition, researches were undertaken 

 with the object of obtaining a reliable method of chemical analysis, by 

 means of which the nitrogen of the coagulablc albumen could be 

 accurately estimated ; such a method is described in Part II. The 

 difference between the total nitrogen and the nitrogen of the coagul- 

 able albumen, designated throughout as ' residual ' nitrogen, should, 

 if the products of tryptic digestion circulate in the blood-stream, be 

 greater in the case of animals killed during active digestion than it is 

 in that of fasting animals. The method of research was also applied 

 to a similar investigation of the liver and the mucous membrane of 

 the small intestine. A large number of animals were used, and it was 

 found then in no case was the average amount of residual nitrogen 

 greater in the case of fed animal than in that of fasting animals. 



The general conclusions drawn from the researches on residual 

 nitrogen may be summarized under the following heads : 



I. The residual nitrogen, as deduced from the analyses of ten 

 sera of fasting animals was found to be 9-10 per cent, of the 

 total nitrogen ; corresponding analyses of the sera of ten fed 

 animals gave the number 9-16. These figures are so close that they 



