328 LOUIS PASTEUR 



occurrence of organization, development, and multiplication 

 of globules, or continued life, carried on by means of the 

 globules already formed. The g?neral results of the present 

 Memoir seem to us to be in direct opposition to the opinions 

 of MM. Liebig and Berzelius." These conclusions, we re- 

 peat, are as true now as they ever were, and are as appli- 

 cable to the fermentation of fruits, of which nothing was 

 known in 1860, as they are to the fermentation produced 

 by the means of yeast. Only, in the case of fruits, it is 

 the cells of the parenchyma that function as ferment, by 

 a continuation of their activity in carbonic acid gas, whilst 

 in the other case the ferment consists of cells of yeast. 



There should be nothing very surprising in the fact that 

 fermentation can originate in fruits and form alcohol with- 

 out the presence of yeast, if the fermentation of fruits were 

 not confounded completely with alcoholic fermentation 

 yielding the same products and in the same proportions. 

 It is through the misuse of words that the fermentation of 

 fruits has been termed alcoholic, in a way which has misled 

 many persons. 10 In this fermentation, neither alcohol nor 

 carbonic acid gas exists in those proportions in which they 

 are found in fermentation produced by yeast; and, although 

 we may determine in it the presence of succinic acid, 

 glycerine, and a small quantity of volatile acids 11 the 

 relative proportions of these substances will be different 

 from what they are in the case of alcoholic fermentation. 



III. REPLY TO CERTAIN CRITICAL OBSERVATIONS OF THE 



GERMAN NATURALISTS, OSCAR BREFELD AND 



MORITZ TRAUBE. 



THE essential point of the theory of fermentation which 

 we have been concerned in proving in the preceding para- 



10 See, for example, the communications of MM. Colin and Poggiale, and 

 the discussion on them, in the Bulletin de I' Academic de Medecine, March 

 ad, Qth, and 30th, and February i6th and 23rd, 1875. 



u We have elsewhere determined the formation of minute quantities of 

 volatile acids in alcoholic fermentation. M. Bechamp, who studied these, 

 recognized several belonging to the series of fatty acids, acetic acid, butyric 

 acid, &c. " The presence of succinic acid is not accidental, but constant; 

 if we put aside volatile acids that form in quantities which we may call 

 infinitely small, we may say that succinic acid is the only normal acid of 

 alcoholic fermentation.' PASTEUR, Comptes rendus de I'Academie, t. xlvii., 

 p. 224, 1 8$ 8. 



