136 



STUDIES ON FERMENTATION. 



November 1st, a feeble, but contiimous fermentation com- 

 menced. This was kept up until Januar}' 2nd, 1873, on which 

 day we transferred the liquid, with its deposit from the test- 

 glass to the flask, when it now seemed to be quite inert. We 

 left it in this flask until December 24th, 1874, without its mani- 

 festing during this long interval any sign of fermentation ; nor 

 did the fungus appear to grow at all. 



We then submitted the liquid to analysis, and found in it, 



per 100 CO. — 



Grammes.* 



Total weight of fungoid growth . . . . 0'25 



Absolute alcohol. . . . . . . . . . 3"4 



Acidity, estimated in its equivalent of sulphuric 



acid . . ., . . . . . . . . 0'12 



Siigar, determined by copper solution . . . . 62 



Sugar, determined after treatment by boiling 



with sulphuric acid, and deduction of 



amount of sugar already obtained (dextrine) ? 1"0 



The total weight of absolute alcohol for the 120 c.c. of 

 fermented liquid was 4"1 grammes — that is, the weight of the 

 alcohol was sixteen or seventeen times that of the plant. 



The structure of the plant differs considerably when it lives 

 surrounded by air, and when it is more or less completely 

 deprived of that fluid. If it has an abundance of air at its 

 disposal, if it vegetates on the surface of a moist substance or 

 in a liquid in which the air held in solution may be renewe<l 

 without being incessantly displaced by carbonic acid gas, we 

 shall see it develop as an ordinary fungoid growth, with a 

 mycelium consisting of filaments more or less slender, branching, 

 and entangled, sending up from the surface of the liquid aerial 

 organs of fructification. This is the well-known form of \cge- 

 tation of the common mucor. On the other hand, if we compel 

 the mucor to live in a saccharine liquid with insufl&ciency of air, at 

 least for some of its parts, the mode of vegetation will change 

 completely, as we have seen in the case oi penicilUum, asperyilluSy 



[* For English equivalent see Experiment I, p. 135.] 



