14 



Scientific Proceedings (85). 



3 per cent. Urea C. L. Extract, NH3 in the Sample, 



Sol., Cc. Cc. Mgm. 



I — O.051 



- S 0.076 



1 5 0.119 



- 10 0.136 



1 10 0.170 



- IS 0.143 



1 15 .0.196 



Ammonium carbonate in passing through the liver is con- 

 verted into urea. Urea on the other hand is converted into 

 ammonium carbonate by an enzyme found in certain bacteria, 

 fungi and a number of higher plants. In 1913 Fosse 1 published 

 some data showing the occurrence of urea in fungi and higher 

 plants, thus pointing to the possibility that the tissues of certain 

 plants may be the site of both the formation of urea and its con- 

 version into ammonium carbonate. 



But all attempts to demonstrate the reversibility of the process 

 whereby urea is formed in the animal body have so far failed. 

 Earlier work on this subject reveals a number of conflicting 

 observations. Perfusion experiments by Wakeman and Dakin 2 

 and by Jansen 3 on the liver under conditions which might be 

 expected to favor a reversion of the reaction failed to show any 

 conversion of urea into ammonia. Recently Barnett and Addis 4 

 found a marked increase of blood ammonia after intravenous 

 injection of large doses of urea. Although this ammonia was 

 shown to be at least in part due to bacterial decomposition in the 

 intestine their experiments suggested the possible derivation of 

 ammonia from urea in the body. But later experiments not yet 

 published fairly establish the fact that the rapid rise of blood 

 ammonia after the intravenous injection of large doses of urea 

 is due solely to the bacterial action in the bowel. 



The presence of urease in the ovaries — if proved — would have 

 been strong evidence in favor of the theory of the reversibility 

 of the ammonia-urea reaction in the body. The results of the 

 experiments here reported fail to confirm the findings of the two 

 earlier investigators. 



1 Fosse, R., C. R. Academ. Sciences, 1913, CLVI, 568. 



2 Wakeman, A. J., and Dakin, H. D., J. Bio. Chem., ion, IX, 327. 



3 Jansen, B. C. P., Arch. Neerland, 1915, II, 594. 



4 Barnett, G. D., and Addis, T., J. Bio. Chem., 1917, XXX, 41. 



