Adeney — Aerobic Bacterial Fermentation, 



7 



all difficulties in the direction here indicated, to preserve without loss 

 the products of the chemical changes, and at the same timG to ensure 

 the purity of the organisms setting up the changes. But, besides this, 

 the field of inquiry is so extensive that it would not be wise, in the 

 present state of our knowledge, to attempt to do so. There are a 

 number of problems in the chemistry of bacterial fermentation which 

 require investigation in connexion with the question of the pollution 

 and purification of water, and which may be regarded as necessary 

 introductory studies to the larger problems above referred to. 



The author desires to describe in this communication a few of such 

 studies. His method of experimenting has been to allow very dilute 

 solutions of simple organic substances of known strength to ferment 

 under aerobic conditions, and to determine from time to time the 

 products of fermentation. The strength of the solutions has been 

 carefully determined, so that the amount of oxygen required in the 

 process of fermentation shall not exceed its solubility in water. The 

 physiological processes which can be conveniently studied by this 

 method are those of respiration and digestion (by enzymic action). 



The Fermentation of Urea. 



Urea has been one of the substances selected by the author for 

 investigation on account of its extremely simple constitution and 

 chemical characters, and also on account of the ease with which it is 

 converted into ammonium carbonate by certain organisms. 



The micro-coccus urese, as is well known, possesses this power to a 

 marked degree ; and Miquel has shown that a number of other organisms 

 also possess it. The change is brought about by the enzyme urase 

 This change, therefore, comes under the physiological process of 

 digestion. 



It is known that the micro-coccus ureae can be cultivated in solu- 

 tions of urea containing phosphates and the other necessary salts. The 

 urea being then the only nutrient organic substance present, must 

 undergo changes in connexion with the physiological processes of 

 respiration and assimilation as well as with that of digestion. Ey the 

 method of investigation employed by the author, the process of respira- 

 tion and digestion can easily be examined when such simple substances 

 as urea are the subject of investigation ; and in the experiments to be 

 described the author proposes to confine himself to the changes 

 possible under these two processes. He hopes to deal with the other 

 processes in a future communication. 



Bl 



