THE FERMENTATION OF CELLULOSE. 193 



wards leaving the mixture to settle, whereupon a brisk fermenta- 

 tion quickly ensues. More accurate information respecting the 

 fission fungus concerned is still lacking. 



118. The Fermentation of Cellulose. 



To dissolve and get rid of what has ceased to live is (according 

 to an appropriate remark made by Pasteur) the task of the fungi 

 in general, and of the fission fungi in particular. Without their 

 activity the circulation of the elements of which the organic world 

 is constructed would quickly come to a standstill, and the surface 

 of the earth become in a few years thickly covered with the dead 

 bodies of animals and plants. Respecting the constituents of the 

 latter a few words will now be devoted to the fate of the Cellulose, 

 of which the greater part of the cell walls of plants is composed. 

 Here the question arises as to how the carbon in this substance is 

 set free again, and the gradual, and finally complete, accumulation 

 of this element in a useless form prevented. In this case once 

 more assistance is afforded by bacteria, which split up the cellulose 

 and remove it out of the way. 



E. MITSCHERLICH (I.) was the first, in 1850, to comment on the 

 natural decomposition of cellulose, by expressing his opinion that 

 it was attributable to the fermentative activity of vibrios. The 

 probability of his view was increased by Popoff's (I.) discovery in 

 1875, that this decomposition process can be moderated or com- 

 pletely arrested by the addition of substances poisonous to bacteria, 

 A closer investigation of the organisms in question was under- 

 taken two years later by VAN TIEGHEM (IV.), who gave them 

 the name of Bacillus amylobacter, and (V.), from microscopical 

 examination only, declared them identical with Pasteur's vibrion 

 butyrique. 



It would be useless at the present time to argue on this 

 assumption, since both observers worked with what were probably 

 complex mixtures of several species, certainly not with pure cul- 

 tures. On the other hand, Van Tieghem's further demonstration 

 that petrified cells of (morphologically) similar fission fungi are 

 also to be found in the fossil coniferse of the Carboniferous period 

 is worthy of mention. 



A. H. C. VAN SENUS (I.), in 1890, endeavoured to obtain a 

 pure culture of the organism giving rise to cellulose fermentation. 

 According to him, a symbiosis of two species is here in question, 

 the one of them which he named Bacillus amylobacter occurring 

 in the form of rods 0.8-1 jot broad and 2-10 ju. in length, which, 

 under special conditions, are stained blue by iodine. When air is 

 admitted they form endospores, which then germinate only when 

 air is excluded. The second of these symbiotic species is of much 

 smaller dimensions, and is by itself, like the B. amylobacter, 

 incapable of fermenting cellulose. For this purpose the conjoint 



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