

THEORY OF FERMENTATION 365 



a proof of a profound chemical work of nutrition and as- 

 similation ? 



We may cite on this subject one of our earlier experi- 

 ments, which is to be found in the Comptes rendus de 

 VAcademie for the year 1857, and which clearly shows the 

 great influence exerted on fermentation by the soluble por- 

 tion that the sugared water takes up from the globules of 

 ferment : 



"We take two equal quantities of fresh yeast that have 

 been washed very freely. One of these we cause to fer- 

 ment in water containing nothing but sugar, and, after re- 

 moving from the other all its soluble particles by boiling 

 it in an excess of water and then filtering it to separate the 

 globules we add to the filtered liquid as much sugar as 

 was used in the first case along with a mere trace of fresh 

 yeast insufficient, as far as its weight is concerned, to affect 

 the results of our experiment. The globules which we have 

 sown bud, the liquid becomes turbid, a deposit of yeast 

 gradually forms, and, side by side with these appearances, 

 the decomposition of the sugar is effected, and in the course 

 of a few hours manifests itself clearly. These results are 

 such as we might have anticipated. The following fact, 

 however, is of importance. In effecting by these means the 

 organization into globules of the soluble part of the yeast 

 that we used in the second case, we find that a considera- 

 ble quantity of sugar is decomposed. The following are 

 the results of our experiment; 5 grammes of yeast caused 

 the fermentation of 12.9 grammes of sugar in six days, at 

 the end of which time it was exhausted. The soluble por- 

 tion of a like quantity of 5 grammes of the same yeast 

 caused the fermentation of 10 grammes of sugar in nine 

 days, after which the yeast developed by the sowing was 

 likewise exhausted/' 



How is it possible to maintain that, xi the fermentation 

 of water containing nothing but sugar, the soluble portion 

 of the yeast does not act, either in the production of new 

 globules or the perfection of old ones, when we see, in the 

 preceding experiment, that after this nitrogenous and min- 

 eral portion has been removed by boiling, it immediately 

 serves for the production of new globules, which, under 



