128 BIO-CHEMICAL JOURNAL 



A series of researches was, therefore, undertaken with the object 

 of investigating the distribution of nitrogen in the tissues in the 

 different stages of nutrition, and of determining the ratio of the 

 nitrogen of the coagulable albumen to the total nitrogen. The 

 difference between the total nitrogen and the nitrogen of the coagulable 

 albumen has, throughout these researches, been termed 'residual 

 nitrogen.' (Ger. Reststickstoff). This expression is more convenient 

 than the older term ' extractives nitrogen,' for, as will be seen in the 

 sequel, the latter, in part at least, appear to form an essential part of 

 the tissue. 



The problem of the residual nitrogen is no new one, and has been 

 attacked by many investigators who have obtained varying results ; 

 their work will be referred to when discussing the experimental part of 

 these researches. The contradictory results obtained are due, without 

 doubt, to the faulty technique employed ; for this reason a comparative 

 investigation has been made of the value of two or three different 

 methods : as a result a new method has been employed, which 

 obviates the fallacies of the other methods. These researches are 

 described in Part II. 



Part III deals with the application of the method to the examina- 

 tion of serum, liver, and small intestine. As a result it was found 

 that the tissues of fed animals do not contain more residual nitrogen 

 than those of fasting animals. Other interesting results were obtained 

 the discussion of which is deferred to Part VI. 



As it is obvious from the results obtained in Part III, that the 

 products of tryptic digestion do not themselves directly act in vivo 

 in inhibiting autolysis, a further search was made for agencies likely 

 to bring about this result. These researches, with all the others 

 bearing on autolysis, are described in Part V. It was found, finally, 

 that acids cause autolysis of the liver without any previous latent 

 period, whilst alkalis have a marked inhibitory action. Now it is 

 known that ammonia is formed from the products of tryptic digestion 

 in the alimentary tract, and stored up in the liver and other tissues^ 

 The quantitative relations of the amounts to the quantity of acid 

 necessary to produce the maximum rate of autolysis have been 



