26 THEORIES OF FERMENTATION. 



lactic acid was produced instead of alcohol. Under the same 

 treatment maltose yields dextro-lactic acid; levulose, levo-lactic 

 acid; and invert sugar the optically inactive acid. A similar 

 observation was made by WEHMER (I.) with respect to a sterile 

 solution of oxalic acid. 



These observations are of great interest to the bacteriologist, 

 from a theoretical as well as a practical point of view, as they 

 convey a special warning to protect his stores of nutrient media 

 from the influence of sunlight. G. Roux, as the result of his 

 adverse experiences, had already given the same warning as to 

 the prejudicial influence of the changes produced by sunlight on 

 bacterial growth, prior to the more exhaustive research by Duclaux. 



These facts have a further interest, more nearly connected 

 with our definition of fermentation, since they demonstrate the 

 occurrence of decomposition processes by purely chemical means, 

 apart from the intervention of micro-organisms. We will there- 

 fore modify our general definition of fermentation, and, in place of 

 stating that fermentation is a process accomplishing transforma- 

 tions of matter with the aid of micro-organisms only, will reverse 

 the phrasing, and say that only such changes as are effected 

 exclusively by the vital action of ferments come within the meaning 

 of the term fermentation. The point of the definition, as already 

 mentioned at the commencement of the previous paragraph, lies in 

 the words italicised. 



However equivalent the action of purely inorganic force on 

 the one hand, and of living organisms on the other may appear, 

 it is so in regard to quality only, the quantitative effects, the 

 amount of substance decomposed in unit time, being widely dif- 

 ferent. Regarded from this point of view, the minute ferments 

 appear as centres for the accumulation of high-tension energy, by 

 the release of which force the decomposition in view can be effected, 

 not only in a shorter time, but also in a more restricted space, than 

 is possible by the action of purely chemical forces. 



