DEAMINIZATION 53 



aseptic and that the breakdown found is due to bacteria. Miss Bostock 

 found that it was almost impossible to get a real aseptic test. She 

 demonstrated, however, that although part of the ammonia given off 

 might be due to the bacterial action, additional deaminization due to 

 ferments present could be proved to take place. She also carried out 

 some observations on foetal tissues, and found that the deaminizing 

 activity started at a very early age. 



Both Lang's and Miss Bostock's experiments are at one in showing 

 that after digestion with the different organ pulps an amide like as- 

 paragine gives up its nitrogen with greater ease than an amino acid like 

 glycine. These in vitro observations are quite contrary to the results 

 which have been obtained when these two particular substances are 

 given by the mouth. Levene and Kober (254), for example, found that 

 if glycine were given per os, practically the whole of its nitrogen appeared 

 rapidly in the urine as urea, whereas in the case of asparagine there was 

 quite a distinct retention of part of the nitrogen. (It is admitted that 

 this is no direct evidence against complete deaminization of asparagine 

 and the subsequent retention of part of the nitrogen liberated, but such 

 a condition is not likely to occur. If retention take place it almost 

 certainly occurs in a compound form, i.e. part of the nitrogen is still in 

 connexion with the carbon chains.) Further, they noted that if aspara- 

 gine were given to a protein starving animal nitrogen was retained, 

 whereas when glycine was given no retention of nitrogen took place. 

 Miss Bostock also carried out a few experiments in connexion with this 

 retention, and she confirmed the observation of Levene and Kober. 

 She found that within eight hours practically all the nitrogen of 

 glycine when given per os, appeared in the urine as urea, but in the 

 case of asparagine in the same time only about 63 per cent, of the 

 nitrogen reappeared as urea in the urine. Apparently then in the 

 digest conditions in vitro, the amino group attached to the carboxyl 

 group of an amide, is much more readily split off than the amino 

 group in the a position of an amino acid, whereas in vivo a certain pro- 

 tection is given to the amide which is not extended to the amino acid. 



At any rate this evidence, slight as it is, suffices to show that the 

 method of research instituted by Lang for the investigation of the 

 deaminizing capacity of tissues is by no means representative of the 

 changes which go on within the normal living tissues. 



