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 resume by Her- 

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



I 



i5^i 



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

 four, and forty-eight hours. 



14. Gas=production from Carbohydrates and Other 

 Fermentable Bodies of the Fatty Series. 



The only gas eventually arising in visible quantity 1 

 in nutrient media which contain no sugar is nitrogen 



(compare page 82). 



1 Sulphuretted hydrogen and ammonia can scarcely occur in visible 

 quantity: 



