PRODUCTION OF GAS. 



89 



Unfortunately the fermentation of cellulose by bacteria 

 is insufficiently studied. So much seems certain, that at 

 least one anaerobic variety converts cellulose into 

 marsh=gas and carbonic acid. Yet Van Senus main- 

 tains that the anaerobic "Bacillus amylobacter," iso- 

 lated by him, attacks cellulose only in symbiosis with 

 another small bacillus. (Compare the r6sum6 by Her- 

 feld, C. B. L. I, 74, 114, and also the special part. ) 



tT? 



^0 



3 



r-^ 



Fig. 11. — Bacterium coli upon sugar-agar, after twelve, twenty- 

 four, and forty-eight hours. 



14. Qas=production from Carbohydrates and Other 

 Fermentable Bodies of the Fatty Series. 



The only gas eventually arising in visible quantity ^ 

 in nutrient media which contain no sugar is nitrogen 



(compare page 82). 



' Sulphuretted hydrogen and ammonia can scarcely occur in visible 

 quantity. 



