STUDIES ON FERMENTATION. 319 



into account the matters which the sugared water gained from 

 the yeast — 



Have we not in this marked increase in weight a proof of life, 

 or, to adopt an expression wliich may be preferred, a proof of a 

 profound chemical work of nutrition and assimilation ? 



We may cite on this subject one of our earlier experiments, 

 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 portion 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 ferment in water 

 containing nothing but sugar, and, after removing 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 afiect 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 efiected, and in 

 the course of a few hours manifests itself clearl3^ 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 considerable quantity of 

 sugar is decomposed. The following are the results of our expe- 

 riment : 5 grammes of yeast caused the fermentation of 12-9 



