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II. 



CHEMICAL CHANGES ATTENDING THE AEROBIC BAC- 

 TERIAL FERMENTATION OF SIMPLE ORGANIC SUB- 

 STANCES. PART I.— UREA, ASPARAGINE, ALBUMOSE, 

 AND ROCHELLE SALT. 



(Plates I.-II.) 



By W. E. ADENEY, D.Sc, Curator and Examiner in Chemistry in the 

 Royal University of Ireland. 



Read December 12, 1904. Ordered for Publication, December 14, 1904. 

 PubUshed March 3, 1905. 



The relation of bacteria to the chemical changes which they bring 

 about in the substances they feed upon and come in contact 

 with, admittedly forms a very large field for inquiry, and one which 

 cannot be said to have been made the subject of accurate investiga- 

 tion to any large extent — certainly not to the extent to which the 

 morphology of the organisms concerned has been studied. 



It is not necessary to emphasize the correctness of this statement. 

 The chemical changes which can be induced by bacteria must be very 

 numerous, seeing that the physiological 'processes of respiration, 

 digestion, assimilation, secretion, and excretion may all be set up 

 during their activity. 



These changes must, moreover, be profoundly modified in solutions 

 of similar substances, fermented by similar organisms, when the supply 

 of atmospheric oxygen is varied. 



Under the ordinary methods of cultivating bacteria, it is impossible 

 to assume that an excess of oxygen can be equally maintained through- 

 out the mass of the solution, owing to the rapid rate of fermentation, 

 and to the sparing solubility of oxygen in water. 



It is obvious, therefore, that under such conditions the liquid 

 medium must be regarded from the chemical point of view as con- 

 stituting varying chemical systems from the surface exposed to the 

 air downwards, and that, if it be desired to study chemical changes 

 under rigid conditions, the method of experimenting must be materially 

 modified. 



It is not easy to devise modifications which shall at once meet with 



