14 THEORIES OF FERMENTATION 



actual determinations is not, in our opinion, lessened by the fact that he was an 

 advocate for spontaneous generation, since at that time (in 1837) there existed 

 no decisive and unassailable proofs to controvert this theory. 



KUtzing did not restrict his researches solely to alcoholic fermentation, but 

 also instituted comparisons with a number of other similar phenomena, regard- 

 ing them all from the same point of view. Even though he must share with 

 others the credit of having discovered the organised structure of yeast, that of 

 determining the vegetable nature of the " mother of vinegar " and recognising 

 its mode of action belongs to him alone. With these discoveries are associated 

 a number of others of minor importance, such, for example, as the physiological 

 basis of the method (propounded by Scheele) of preparing gallic acid by allowing 

 a solution of pyrogallic acid (e.g. gall-nut extract) to become infested with 

 mould. The numerous phenomena he brings under our notice constitute so 

 many proofs of the theory that fermentation cannot be regarded as a purely 

 chemical process. " It is well known that chemistry explains vinous fermenta- 

 tion by the reaction of the so-called gluten on the amylum (starch) and sugar. 

 I must firmly maintain that the explanation does not give me a clear idea of 

 the process, and I am inclined to doubt whether others are more fortunate in 

 this respect. It is, however, certain that the entire process of alcoholic fermen- 

 tation is dependent on the formation of yeast, and the acid fermentation on the 

 formation of the vinegar plant. . . . Along with the increased growth of these 

 organisms the reproductive impulse also increases, and,* concurrently, their 

 reaction on the liquid present. ... In so far as fermentation is synonymous 

 with a reciprocal reaction of oi'ganic and inorganic bodies on the constituents of 

 a given liquid which may be regarded as forming the nutrient medium of the 

 organic product, so is it necessarily synonymous with every organic vital func- 

 tion : wherefore organic life = fermentation. On the other hand, such pro- 

 cesses as lead to the production of vinegar from alcohol by the use of platinum 

 black or other similar methods, cannot be compared with fermentation, being 

 purely chemical, whilst fermentation is an organo-chemical process, as is also the 

 life process of any organic body." " 



One of the three members of the committee appointed by the Academie des 

 Sciences of Paris to report on the memoir presented by Cagniard namely, 

 TUEPIN (I.) took the opportunity thus afforded of experimentally dilating 

 upon his compatriot's work, and of amalgamating these new " discoveries " 

 with the revelations of Schwann and KUtzing. In this way a volume, 

 containing more pages than Latour's communication had columns, came into 

 existence, without, however, adding to our knowledge in the slightest degree. 

 Turpin seems, however, to have thoroughly known his public, since he is even 

 now regarded as one of the founders of the vitalistic theory of fermentation, 

 not only by compilers of text-books, but also by actual investigators, from whom 

 one might more reasonably expect a more thorough study of the original works 

 of their predecessors. 



15. Liebig's Decomposition Theory. 



Two years subsequent to the publication of the works of Cagniard, Kutzing, 

 and Schwann, Liebig placed before his colleagues a new theory, according to 

 which fermentation was a purely chemical reaction. 



In order to avoid judging this chemist unreasonably, one must bear in mind 

 the age wherein this theory was promulgated. Synthetic organic chemistry 

 had just been founded. Eleven years previously (1828) Wbhler had succeeded 

 in artificially preparing urea, to the astonishment of his contemporaries, who 

 had hitherto considered as impossible the artificial production of organic 



