158 BIO-CHEMICAL JOURNAL 



may be regarded as practically identical ; the difference lies well within 

 the limits of experimental error. The individual sera give numbers 

 which do not differ very greatly from this mean. 



Furthermore In no case was any substance yielding the biuret 

 reaction detected in the filtrate from the coagulum 



II. In the liver, the percentage of residual nitrogen is larger 

 (14*2) in the case of the fasting than of the fed animals (12-3). This 

 result is probably due to the fact that autolysis was already taking 

 place in the livers of the fasting animals at the time of death. 



In no case again were any bodies yielding the biuret reaction to be 

 found in the filtrates from the coagulum. 



III. In the case of the mucous membrane of the small intestine, 

 the following results were arrived at : 



(a) The residual nitrogen varies within very narrow limits, if 

 indeed, at all. The analysis made of six samples taken 

 from six different ani'mals gave in five cases numbers 

 that agree so closely that had they referred to a single 

 homogeneous body they could hardly have been more 

 satisfactory. From this we may conclude that the 

 percentage of residual nitrogen in the mucous membrane 

 of the intestine is a constant for a particular species of 

 animal. 



(7>) It is not influenced by the state of nutrition. 



(<:) It varies with different animals. It was found to be 38*8 

 in the case of the dog (two samples), 33'2 in the case 

 of the cat (six samples), 32-3 in the case of a pig, 28-8 

 in a rabbit (two samples), 27*6 for a sheep, and 19^2 for 

 an ox. It will be noticed therefore, that the percentage 

 is higher in the case of carnivora than of herbivora. 



(^) It is also higher in the case of the mucous membrane of the 

 intestine than in any of the other tissues investigated. 



(<?) In addition, the mucous membrane shews certain other 

 peculiarities. Attention has already been called to the 

 fact that, unlike other tissues, when incubated with 

 water it immediately commences to undergo disintegration- 



