176 STUDIES ON FERMENTATION. 



is clear, and it is full of fine, yellowish granules, which present 

 a perfect resemblance to the large ferment-cells of fruits, pro- 

 ceeding from the germ-cells on the surface of those fruits, 

 when it begins to appear in sweet juices ; 6 is a long filament, 

 sprung from the preceding cell ; and, last of all, a is a joint 

 and its hud, in which the border is not yet very clearly defined ; 

 it has scarcely any granules, and is finer than the others, be- 

 longing, in short, to the small ferment form represented in 

 Plate XI. Here, then, we see the transition of the large ferment 

 to the small, on the same branch, after two generations from 

 the germination of the germ-cell d. This observation cor- 

 roborates the opinion maintained by us, that in Figs. 33, 31, 

 36, as in Plate X., we have not a mixture of two ferments, the 

 one consisting of large, elongated filaments, the other of small 

 cells, but one and the same ferment, the difierences in the 

 form and size of which depend on particular conditions. The 

 smallest ferment-form very soon becomes the only one visible, 

 and it preserves its peculiar appearance in successive growths 

 from inability to return to the full, elongated, filamentous 

 forms before undergoing a prolonged exhaustion. The ferment 

 of miicor would probably afibrd similar indications : it would 

 be very interesting to find out. 



The following is one of the most curious of the forms pre- 

 sented by saccharomijces pastorianus, occurring after exhaustion 

 in a sweet mineral liquid. The ferment, taken from a closed 

 vat, in which it had been used for beer, was sown in the 

 mineral liquid on July 4th, 1873. The following days the 

 ferment developed feebly, but perceptibly, and gradually^ in- 

 creased in bulk. The flask was left to itself in an oven at 

 25° C, (77° F.) until December 3rd, when we ascertained that 

 all the sugar had fermented. We then sowed a trace of the 

 deposit, which had become abundant, in a flask of pure wort. 

 On December 4th there was no perceptible change. On 

 December 5th, however, fermentation was in active progress ; 

 a large quantity of froth covered the surface of the liquid, 

 and a considerable deposit of ferment had already taken 



