18 



Proceedings of the Royal Irish Academy. 



3. Of the proportions of the urea which suffered respiratory and 

 enzymic changes in an experiment, in which the urea had undergone 

 complete metabolic change, about two-thirds was completely oxidised, 

 according to the above equation, and one-third was converted into 

 ammonium carbonate by hydrolysis. 



4. Small quantities of oxygen are also taken up by other physio- 

 logical processes not yet examined. 



5. Products of hydrolytic action have not been observed at the 

 earliest stages of the development of the organisms. 



6. When the urea was associated with such an organic compound 

 as Rochelle salt, it apparently suffered no change until enzymic action 

 set in, and was apparently not affected by other physiological changes, 

 these latter being confined to the Rochelle salt, and also to the 

 dissolved atmospheric nitrogen. 



7. Decided quantities both of the carbon and nitrogen of the urea 

 fermented, and of the atmospheric oxygen consumed, have been noticed 

 as having been taken up, no doubt, by constructive and other physio- 

 logical processes ; but these have not yet been completely examined. 



The Fermentation of Asparagine. 



Asparagine is a substance of well-defined constitution, and easily 

 undergoes enzymic change into aspartic acid and ammonia ; and it has 

 for these reasons been included amongst the substances for study in 

 this investigation. 



The experiments with this substance have been conducted in a 

 precisely similar manner to those with urea. The descriptions of 

 them, and the results obtained, will be found in Table VI. 



On reference to the Table it will be seen that the first experiment, 

 IN'o. 16, was stopped just at the commencement of fermentation, and 

 the results give the chemical changes which were set up during the 

 earliest stages of activity of the organisms ; thus 0-61 cc. oxygen was 

 absorbed, and 1-4 cc. COg and 0*001 grm. nitrogen as ammonia were 

 formed. 



The results of the next experiment, Is^o. 17, and also ]S"o. 18, 

 indicate more advanced steps of the fermentation ; but in these cases 

 the oxygen originally present had been completely absorbed ; conse- 

 quently the results may have been slightly affected by anaerobic 

 conditions. It will, however, be noticed that the amount of ammonia 

 formed in both these experiments was very large in comparison with 

 the volumes of carbon dioxide which were also formed. Th^ nitrogen 



