600 VITAL ACTIONS OF THE LOWER FUNGI. 



Dextran Fermentation. 



fermentation ^e only directly suitable material is grape-sugar; 

 cane-sugar does not ferment directly, but, as the ferment- 

 ing agents furnish large quantities of invertin, the 

 decomposition of the cane-sugar is only slightly delaj'ed. 

 It not uncommonly occurs spontaneously in the juice of 

 beet-root, and hence is much dreaded in sugar factories. 

 The fungus which causes the fermentation is leuconostoc 

 mesenterioides. The decomposition results mainly in 

 the formation of large quantities of a jelly-like sub- 

 stance the dextran. We have no accurate knowledge 

 as to the process of the fermentation ; as to the morpho- 

 logical characters of the fungus, see page 214. 



Cellulose Fermentation (Marsh Gas Fermentation}. 



Cellulose Cellulose, in the form of dead plants, straw, paper, or 



cotton-wool, frequently undergoes solution and fermen- 



Materials and tation by bacteria. Hoppe-Seyler * was able to set up this 

 fermentation by all kinds of mud, and also by earth from 

 fields, meadows, and woods; according to Deherain t and 

 Gayon J it often occurs in dung; on the whole, it seems 

 to be extremely widely distributed. Tappeiner has 

 shown that cellulose is dissolved and broken up by the 

 same fermentation in the intestinal canal of the rumi- 

 nants. The bacteria which set up this fermentation 

 have not, as yet, been cultivated pure. As to the 

 chemical processes, Tappeiner has made several inves- 

 tigations, and found that there are two kinds of fermen- 

 Cation of cellulose ; the first occurs in neutral extract of 

 meat solution containing 1 per cent, of extract of meat, 

 in which purified cotton-wool or paper pulp is suspended; 

 under these circumstances, carbonic acid and marsh gas 

 escape (in the first few days the marsh gas is in much 

 greater excess than at a later period); further, small 



* Hoppe-Seyler, Chem. Ber., vol. xvi. 



t Deherain, Compt. rend., vol. 9P. J Gayon, ibid. 



