20 



Proceedings of the Royal Irish Academy, 



as ammonia amounts to one-half the nitrogen originally present in the 

 asparagine, while the carbon dioxide only accounts for one-seventh of 

 the carbon. Such a result cannot be referred to anaerobic conditions, 

 and it may be concluded, having regard to the ease with which 

 asparagine is hydrolysed, that in both the experiments practically the 

 whole of it was changed by enzymic action into aspartic acid and 

 ammonia, and that the respiratory changes were subsequently exerted 

 upon the aspartic acid so formed, in accordance with the following 

 equations : — 



CoHaCNHo) (CO . NHoJ (CO2H) + H2O = C2H3(]S"H2) (C02H)2 + I^Hs. (1) 

 CoH3(NH2)(<^02H)2 + 3 O2 = 4 CO2 + NH3 + 2 H2O. (2) 



Erom equation ( 1 ) it is seen that, as a result of hydrolysis, one-half 

 of the nitrogen in asparagine is retained in the product, aspartic acid, 

 and one-half goes to form ammonia. 



Since, in the case of asparagine, ammonia is the sole inorganic 

 product of enzymic change, the whole of the carbon dioxide formed 

 during its fermentation may be regarded as the result of respiratory 

 changes. 



The experiments recorded in the Table form a series illustrating 

 different stages of fermentation from commencement to completion ; 

 and the course of the fermentative changes are best shown by the 

 accompanying curves ; thus, when the carbon dioxide and ammonia 

 are plotted together, the course of change is represented by two 

 straight lines, one showing the course of enzymic changes, the other 

 the after-effect of respiratory changes upon the aspartic acid, the 

 organic product of the first-named changes. 



"When the volumes of carbon dioxide formed and of oxygen absorbed 

 are plotted together, a straight line is also obtained. 



It may, therefore, be concluded that the absorption of the greater 

 part, if not of the whole, of the oxygen may also be regarded as due 

 to respiratory changes. 



The quantities of carbon dioxide and of ammonia which resulted 

 from the complete fermentation of the solutions of asparagine 

 employed are shown by the results of experiments 23 and 24 with the 

 first solution, and by experiments 28 and 29 with the second solution. 

 They maybe taken to be 56*25 cc, and 0*01 grm. nitrogen as ammonia, 

 per litre. These quantities represent 67*9 per cent, of the carbon, and 

 72 per cent, of the nitrogen in the aspartic acid formed by the 

 hydrolysis of the asparagine. 



