398 



L. D. BUSHNELL 



In the case of lactose, inulin, arabinose and xylose there appears 

 to be no doubt that these carbohydrates were not attacked to any 

 extent. With mannitol there was an increase of gas and but 

 httle increase in acid above that in peptone solution alone. We 

 have concluded that there was a slight fermentation of mannitol. 



In most experiments the predominating gas was CO2. Hy- 

 drogen was obtained in all cases except \\dth the cultures upon 

 asparagus at the beginning of the fermentation. One point of 

 interest in this connection is the ratio of Ho to CO;. In all our 

 tests the amount of CO2 increased with the age of the fermenta- 

 tion, while the Ho remained practically stationary after the first 

 few days. This caused a change in the ratio of H2 to CO2 from 

 day to day. Most authors mention a ratio between these gases 

 as determined at a certain time. By determining it at intervals 

 the ratio might be somewhat different as shown in this case. 

 Apparently the ability of the organism to form hydrogen was lim- 

 ited to the beginning of fermentation; or the substance from 

 which this gas was formed was used up in the earUer stages; or 

 the hydrogen was oxidized as. it was formed, as has been suggested 

 by Nikitinsky, (1907) and Kaserer (1906). 



According to Perdiix (1891) B. amylomyze produced a gas of 

 variable composition with the different carbohydrates at different 

 ages of the culture. He gives the following table to show this 

 (for glucose). 



V = volume, R = ratio, D = difference. 



Grimbert (1893) found that his B. orthobuUjlicus growing in 

 glucose solution without chalk produced the following results: 



