130 STUDIES ON FERMENTATION. 



liquid that remained in the flask was covered with a gelatinous 

 and frothy mycelium. 



On October 20th, 1872, after a lapse of three months and a 

 half, we poured the liquid from the test-flask attached to flask 

 C back again to that flask. The test-flask connected with flask 

 B we left untouched alongside the other flasks to serve as a 

 means of comparison. 



On October 21st, 22nd, 23rd, we observed nothing; on succeed- 

 ing days, however, some patches of bubbles appeared on the surface 

 of the liquid in flask C, and clusters of mycelium buoyed up by 

 the bubbles of gas which they imprisoned. Life had resumed 

 its course, and with life fermentation had recommenced. 

 What had been the cause of this change in the condition of the 

 liquid, after an absolute quiescence of three months ? There 

 can be but one answer to this question : for in the other vessels 

 there was no corresponding movement, or sign of life to be 

 detected. In this vessel, however, an aeration of the plant had evi- 

 dently taken place, consequent on the decautation and contact with 

 the atmosphere of the flask, which communicated with the exterior 

 air through the curved tube. This aeration had been absent or 

 ineffective before decantation, in consequence of the great depth 

 of liquid in the test-flask, the surface of which, too, was covered 

 by a mass of mycelium filaments, itself effectually opposing any 

 aeration of the liquid. Moreover, the surface of the liquid in 

 the narrow neck of the test-flask had necessarily been covered by a 

 layer of carbonic acid gas. We may investigate more thoroughly 

 the influence of aeration, and its relation to the resumption of 

 life in the mycelium of mucor, by restoring the liquid to its 

 previous condition of depth and so cutting off" again contact 

 with the air. 



For this purpose, on October 31st we decanted Once more the 

 liquid and its deposit from the flask into the test-glass. The 

 same evening a slight but continuous fermentation, with forma- 

 tion of froth, appeared on the surface of the liquid in the neck 

 of the test-glass. Fermentation although never vigorous, con- 

 tinued the following davs, and until December 20th. 



