STUDIES ON FERMEIs'TATION. 75 



signs of fungoid growths, without any trace oi mycoderma rini, or 

 lines indicative of the presence of tonilce, whilst six of the seven 

 in our laboratory had their sides covered with a white precipitate, 

 and on the surface of the liquids a layer of isolated patches of 

 fungoid growth. The liquid in these latter basins was poured 

 into a long-necked flask, which it nearly filled, and in the 

 course of forty-eight hours it began to show signs of alcoholic 

 fermentation.* This is another striking proof of the difference 

 between the number of germs of ferment and iorulacece in the 

 air of our laboratory and that of an ordinary room. 



We append drawings of the torulce found in the six labora- 

 tory basins (see Sketches I., II., III., IV., V., VI. of Fig. 12). The 

 abundance of the germs of these organisms in our laboratory 

 is very striking, and is doubtless due to the nature of the work 



* It is to be remarked that in this case, as in the case recorded 

 § IV. p. 70, in order to detect with certainty any alcoholic ferment, the 

 contents of the basins were transferred to a long-necked flask ; since 

 where, as in the basins, a liquid has a large surface exposed to spon- 

 taneous impregnation, the strictly alcoholic fermentation may escape 

 observation. The reason of this is that, when a liquid of large surface 

 but small depth is exposed to the air it affords a suitable medium for the 

 active development of moulds, which, by absorbing the oxygen which 

 would dissolve in the liquid, checks the growth of the ferment, or even 

 prevents its germination altogether. As a matter of fact we shall see 

 that for their growth and multiplication ferment cells, and still more 

 ferment germs (the difference between the two will appear in Chap. V.), 

 require a larger supply of oxygen just in proportion to their age, state of 

 desiccation, and distance from the budding condition. Now, if the spores 

 of moulds be present and effect a settlement in the liquid, the increase of 

 the ferment, or even its actual germination, is prevented. But by collect- 

 ing the liquid in a deep and narrow vessel, such as a long-necked flask, 

 after it has been exposed to spontaneous impregnation, we deprive the 

 moulds almost completely of oxygen, and so allow the feiTaent to exert 

 its peculiar energies. The mere act of transferring enables the liquid to 

 take up a sufficiency of oxygen, and a liberation of gas very speedily 

 shows that fermentative action is going on. We must add further that 

 sometimes in a liquid of large surface and shallow depth, in which but 

 little ferment is formed, the evolution of carbonic acid gas may fail to be 

 detected, by reason of its diffusing itself into the air slowly as it is 

 formed. 



