190 STUDIES ON FERMENTATIOX, 



see if we can find any facts analogous to those presented by 

 saccharomyces padorianus (Chapter V. § 1). 



"With this object in view, on May 6th, 1874, we impregnated 

 two fresh flasks of sweetened water with some of the contents of 

 the before-mentioned flask, which we had refilled with sweetened 

 water on May 2nd. On May 13th we decanted the liquid, which 

 was still very sweet, from one of these two fresh flasks, which 

 could hardly be said to have fermented at all — the quantity of 

 yeast in them being so small — and replaced it with some wort. 

 Strange to say, on the morning of the 14th we found an 

 appreciable growth of yeast, and a froth of carbonic acid gas 

 on the surface of the liquid. The yeast therefore was not dead, 

 although its fermentative powers had been exhausted. There 

 was, however, no remarkable feature in connection with its re- 

 vival, nor did we find the slightest trace of any of the elongated 

 ferment-form. What we got was simply the ramified groups 

 of " high " yeast again, in round cells, but nothing more. 



Fearing that our yeast might not have remained for a 

 sufficient time in the sweetened water for exhaustion, we set 

 aside, for a whole year, the other flask which we had prepared 

 on May 6th. On May 16th, 1875, we decanted the sweetened 

 liquid and replaced it with wort. This time, however, there 

 was no revival of the yeast ; it had perished. Fortunately, we 

 had also saved the flask of yeast and sweetened water which 

 was prepared on May 2nd, 1874, as already mentioned, and in 

 this case, as will be seen, the vitality of the 3'east had not been 

 extinguished, doubtless, in consequence of the formation of 

 what we shall presently designate by the name of aerobian fer- 

 ment. On May 16th, 1875, we decanted the liquid from this 

 last flask, and replaced it with wort. On the next day the 

 surface of the wort was covered with a thin froth, indicating 

 the commencement of fermentation. The microscope revealed 

 nothing extraordinary, or indicative of the fermentation of any 

 special ferment. To assure ourselves that our ferment had 

 remained "high," we sowed some of it in a fresh flask of 

 wort on May 19th, and then, seven hours after impregnation, 



