24 THEORIES OF FERMENTATION. 



place to a term that is both more accurate and more compre- 

 hensive. 



The phenomena of fermentation forming the starting-point 

 from which the workers from Cagniard to Nageli began their 

 researches, and which up to the present have been the sole subject 

 under our consideration, possess one characteristic in common, i.e. 

 they are always attended by the degradation of complex organic 

 compounds into simpler ones. By regarding this characteristic by 

 itself, fermentation might be denned as a decomposition of organic 

 substances by the agency of fungi. 



The researches of the past fifteen years (1880-1895) have, 

 however, necessitated considerable modifications of the words 

 italicised. The study of the bacteria of the nodules of leguminous 

 plants has taught us that their main function consists in bringing 

 about the combination of free atmospheric nitrogen, hence their 

 action is not a decomposing (analytical) one, but is synthetic or 

 constructive, so that in respect of these organisms our definition 

 will have to include the word "transformation." The adjective 

 " organic " may still remain, since the microbes in question require 

 organic nutriment in addition to the free nitrogen. 



We shall, however, find ourselves constrained to reject this 

 latter term when we come to the study of nitrification, and make 

 the acquaintance of another group of microbes able to dispense 

 with organic nutriment, and indeed thriving and acting most 

 effectively only when surrounded by inorganic substances exclu- 

 sively. Consequently we arrive at the following final and conclusive 

 definition : Fermentation is a decomposition or transformation 

 of substances of various kinds, brought about by the vital 

 activity of fungi. 



20. The So-called Spontaneous Fermentation 

 of Sweet Fruits. 



The point of the preceding definition lies in the concluding 

 words, which restrict the term fermentation to such decompositions 

 or transformations as are produced by the vital activity of fungi. 

 It is, however, not impossible for similar decompositions to be 

 effected in other ways, especially by the aid of other vegetable cells 

 differing from fungi. An example of such a reaction, resembling 

 fermentation but not induced by fungi, is afforded by the so-called 

 spontaneous fermentation of fruit. 



The first reliable data with regard to this phenomenon were 

 collected by LECHARTIER and BELLAMY (I.) in 1869, all previous 

 observations having to be disregarded because they do not show that 

 the activity of yeast-cells was precluded. Starting with the notes 

 made in 1821 by their compatriot BERARD (I.), these French in- 

 vestigators succeeded in establishing the fact that sweet fruits, e.g. 

 cherries, when kept in an uninjured condition and free from yeast 



