BIO-CHEMICAL JOURNAL 



incubated with water, a gradual elimination takes place in four hours ; 

 the degradation changes then cease. This phenomenon has been 

 already described in the first paper (Journ. Physiol, 32, p. 159) ; it is 

 to be distinguished from ordinary autolysis. 



The physical constants determined show that very little change 

 takes place on coagulating the moist fresh tissue ; no more, in fact 

 than takes place in the case of the liver, which does not contain a large 

 quantity of residual nitrogen, and which shews very small change 

 during the first four hours of incubation with water. All these facts 

 justify the conclusion that the greater part, at least, of the residual 

 nitrogen of the small intestine is not mere ' extractive ' nitrogen, but 

 represents a part of the protoplasm molecule which is held in loose 

 combination, and which is intimately connected with the processes of 

 nitrogenous metabolism, as is evidenced from the fact that it is greater 

 in quantity in the case of carnivorous animals than in that of 

 herbivora. This point will be referred to again in the summary, 

 (part VI). 



Comparison of the ratio residual nitrogen : total nitrogen in 

 different animals. 



Dog No. i. Fasting ... 41 ': 



Fed .*.. i 3'8-S (average). 



In the case of the ox, the sample for analysis was not taken from 

 the whole intestine. 



In the rabbit, only small quantities could be obtained for each 

 analysis ; these were accurately weighed on a fine balance. 



SOME PHYSICAL CONSTANTS OF TISSUE EXTRACTS 



The following determinations of physical constants were made. 

 The results throw but little light on the method of combination of the 

 residual nitrogen with the main part of the bioplasm. It might be 



