330 ANNUAL REPORT OF THE Off. Doc. 



species, such as Bacilhis megatherium, Bacillus fliiorescens-liquefa- 

 ciens and Bacillus vulgaris, are known to produce them. 



The action of invertin is favored by the presence of small amounts 

 of acid; it is therefore likely that in the acid fermentation of plant 

 tissues and the normal presence of invertin ferments there is every 

 condition favorable for the conversion of all the cane sugar into 

 glucose independent of the action of bacteria or other micro-organ- 

 isms. 



(c) Tlie I ermentation of Glucose. — From the foregoing statement 

 it has been seen that all of the carbohydrates mentioned are eventu- 

 ally converted into glucose mainly through the action of enzymes. 

 It is in this form that the}' are supplied to the various soil organ- 

 isms. Through their agency glucose is converted into the various 

 organic acids, into one or more of the alcohols, with or without the 

 evolution of gas in the form of carbon dioxide and hydrogen. 



The great majority of bacteria possess greater or less power of 

 producing one or more of the organic acids from glucose, although 

 much work has yet to be done in determining the kinds of acids pro- 

 duced by different species. The following table shows the products 

 of the fermentation of glucose by a number of common bacteria: 



Bacillus acidi-Iactici — acetic and lactic acids, traces of alcohol and 

 gas. 



Bacillus aerogenes — acetic, lactic and succinic acids, alcohol, car- 

 bon dioxide and hydrogen. 



Bacillus typhosus — lactic acid. 



Bacillus coli — acetic, formic and lactic acids. 



Bacillus prodigiosus — formic and succinic acids. 



Bacillus butyricus Botkin — acetic, butyric, formic, propionic, lac- 

 tic, and succinic acids; butyl and ethyl alcohol, carbon dioxide and 

 hydrogen. 



Bacillus amylozyma Perdrix — acetic and butyric acids, carbon 

 dioxide and hydrogen. 



Cholera Micospira — lactic acid. 



Micrococcus pyogenes — lactic and valerianic acids. 



Streptococcus pyogenes — lactic and volatile organic acids. 



The organic acids produced by the fermentation of glucose tend 

 to combine with any free base in the soil such as lime, soda, potash, 

 and, in a measure, to decompose carbonates. But where this base is 

 not present in sufficient quantity the free acids accumulate and the 

 scii becomes sour. Under active cultivation, however, the acids and 

 their salts undergo a still further fermentation whereby they are con- 

 verted into carbon dioxide and marsh gas (CHJ. 



Thus cultivation has a tendency to overcome acidity by stimulating 

 the growth of those bacteria which destroy organic acids. 



