.'36 STUDIES ON FERMENTATION. 



example, is exposed freely to the air, it is besieged simul- 

 taneously by spores of miicecUnes, as well as germs of bacteria, 

 leptofhnx, vibrios, dc, but the latter germs are checked in their 

 development, if, indeed, they are not actually destroyed, by the 

 acidicy of the liquid ; and we should never find them there in 

 their adult state. 



Most moulds, on the other hand, thrive in acid liquids, and 

 therefore they are generally found alone. If we began by 

 saturating must with carbonate of lime, previously dried or 

 otherwise, we should observe opposite phenomena ; bacteria, 

 lactic ferments and butyric vibrios would invade our fields long 

 before the spores of mould had time to grow, since the germina- 

 tion of these proceeds very languidly in neutral or alkaline 

 liquids, and an infusion once occupied by a living organism has 

 much trouble in nourishing others ; the early developments 

 consume the alimentary substances, especially the oxygen. 



Differences as marked as these in the adaptability of certain 

 liquids to certain growths give rise to innumerable illusions, and 

 are one of the chief sources of error in the study of this subject. 

 If we sow in aa acid liquid, such as must, an alcoholic ferment, 

 the development of which is not arrested by the acid character 

 of our medium, it will multiply there, and we shall have no 

 difficulty in growing it over and over again in the same acid 

 medium. This being the case, let us suppose that our alcoholic 

 ferment is impure — let us say, mixed with filaments of turned 

 wine, which are due to a ferment checked in its development 

 by the peculiar qualities of the must. In repeating the growth 

 of this alcoholic ferment in the must the filaments which were, 

 by supposition, present in our first sowing, and which cannot 

 reproduce themselves in the must, or do so with great difficulty, 

 will become very scarce in the fields of our microscope ; they 

 will not, however, cease to exist, for the repetition of our attempts 

 to grow them only serves to spread the original germs over a 

 larger surface ; and, although the eye fails to detect them, they 

 will only have become more difficult to discover. At this point 

 the experimentalist is in danger of falling into error, for when 



