THEORY OF FERMENTATION 325 



ever, can be truer than that opinion, and at the present 

 moment, after fifteen years of study devoted to the subject 

 since the publication to which \ve have referred, we need 

 no longer say, "we think," but instead, "we affirm," that 

 it is correct. It is, as a matter of fact, to alcoholic fermen- 

 tation, properly so called, that the charge to which we have 

 referred relates to that fermentation which yields, besides 

 alcohol, carbonic acid, succinic acid, glycerine, volatile 

 acids, and other products. This fermentation undoubtedly 

 requires the presence of yeast-cells under the conditions 

 that we have named. Those who have contradicted us have 

 fallen into the error of supposing that the fermentation of 

 fruits is an ordinary alcoholic fermentation, identical with 

 that produced by beer yeast, and that, consequently, the 

 cells of that yeast must, according to own theory, be 

 always present. There is not the least authority for such a 

 supposition. When we come to exact quantitative estima- 

 tions and these are to be found in the figures supplied by 

 Messrs. Lechartier and Bellamy it will be seen that the 

 proportions of alcohol and carbonic acid gas produced in the 

 fermentation of fruits differ widely from those that we 

 find in alcoholic fermentations properly so called, as must 

 necessarily be the case since in the former the ferment- 

 action is effected by the cells of a fruit, but in the latter by 

 cells of ordinary alcoholic ferment. Indeed we have a 

 strong conviction that each fruit would be found to give 

 rise to special action, the chemical equation of which would 

 be different from that in the case of other fruits. As for the 



essential products of the special phenomenon under observation. Bearing 

 in mind this fact in reference to the nomenclature that we have adopted. 

 it will be seen that the expression alcoholic fermentation cannot be applied 

 to every phenomenon of fermentation in which alcohol is produced, inas- 

 much as there may be a number of phenomena having this character in 

 common. If we had not at starting defined that particular one amongst 

 the number of very distinct phenomena, which, to the exclusion of the 

 others, should bear the name of alcoholic fermentation, we should in* 

 evitably have given rise to a confusion of language that would soon pass 

 from words to ideas, and tend to introduce unnecessary complexity into 

 researches which are already, in themselves, sufficiently complex to necessi* 

 Ute the adoption of scrupulous care to prevent their becoming still more 

 involved. It seems to us that any further doubt as to the meaning of the 

 words alcoholic fermentation, and the sense in which they are employed. 

 In impossible, inasmuch as Lavoisier, Gay-Lussac, and Thenard have applied 

 this term to the fermentation of sugar by means of beer yeast. It would 

 be both dangerous and unprofitable to discard the example set by these 

 illustrious masters, to whom we are indebted for our earliest knowledge 

 of this subject 



