52 THE PHYSIOLOGY OF PROTEIN METABOLISM 



Deaminizing Capacity of Tissues. 



As regards the presence of enzymes in the tissues which led to the 

 formation of ammonia, the work of Loewi (260) and of Jacoby 

 (211) was the earliest, although their evidence was not very complete. 

 Jacoby found that in the fluid which he obtained by pressure from 

 pulped liver tissue the amount of ammonia increased after incubation 

 at 40 C. This ammonia, he believed, was derived from substances 

 like amino acids which were not deaminized by boiling with acids- 

 Loewi (260) showed that the amino group in glycine was converted by 

 the action of liver pulp into a substance which, although it was not urea, 

 resembled this substance, particularly as regards the ease with which 

 it could give up its ammonia. Lang's paper (238) was the first serious 

 attempt to attack the question of deaminization by testing the action 

 of the different tissues on the amino acids themselves. Lang obtained 

 results which showed that the deaminization in the tissues was ex- 

 tremely active, although there was a certain degree of specificity, i.e. 

 some amino acids were quite untouched by one tissue, whilst actively 

 broken down by another. Thus glycine was much more readily broken 

 down by the intestine than the liver, and it was not attacked by the 

 spleen tissue at all. He found, too, that the amides, asparagine and 

 glutamine, gave up their ammonia very readily in the presence of any 

 tissue. The short experiments which he carried out with fresh tissue 

 under aseptic conditions gave better results than the long experiments, 

 in which he used material preserved by means of an antiseptic. 



Although a great deal of stress has been laid on these experiments 

 of Lang, which were carried out in 1905, so far as I am aware, no full 

 and direct confirmation has been published. The facts observed fitted 

 in with the current beliefs strengthened them indeed with the result 

 that they received but little criticism. Miss Bostock (71) has recently 

 reinvestigated this question, and has repeated some of Lang's experi- 

 ments. She found that Lang's main contention was true that deaminiz- 

 ation took place, but she also found that the degree of deaminization 

 was much less marked than Lang described. She further found that 

 Lang's results with tissue pulp with and without antiseptic could not 

 be fully substantiated. Like Lang, she showed that the amide bodies 

 yielded their nitrogen with greater readiness than the amino acids. 

 Of course, on account of the well-known capacity of many bacteria to 

 deaminize, one of the objections which has been raised against the so- 

 called " aseptic " autolytic experiments is that they are not really 



