6 MICROBES AND TOXINS 



Pasteur discovered the transformation of the lactate into the 

 butyrate by the butyric vibrio ; the butyrate can be completely 

 consumed in its turn by the moulds. 



The glucosides (compounds of sugar with an organic body, 

 an alcohol or phenol) are decomposed into their two elements. 

 A diastase, tannase, secreted by the Aspergillus, splits tannin 

 into two molecules of gallic acid, from which other moulds 

 produce again carbonic acid and water. 



Just as there is not one starch but several, so there are 

 several celluloses, which resemble starches but are more 

 stable : (CgHjQOg)^. They form the walls of vegetable cells, 

 and make up one-third of the weight of the straw, which is 

 the principal component of farmyard manure. If the celluloses 



FIG. I. The microbe which ferments cellulose, described by Omeliansky : 

 bacilli with spores. 



were not decomposed and restored to circulation, the earth 

 would soon be cumbered with useless refuse material. But from 

 the beginning moulds establish themselves on the outer skin of 

 the living plant ; when it dies they invade its tissues, attacking 

 first the sugar and then the cellulose, the latter being hydrolysed, 

 transformed into sugars and consumed. The B. Amylobacter 

 of Van Tieghem, an anaerobe, produces from cellulose 

 hydrogen, carbonic acid and butyric acid. Omeliansky has 

 demonstrated two methods of anaerobic fermentation in 

 cellulose, one with production of hydrogen, the other with 

 production of methane. Those ferments which in a tube in 

 the laboratory decompose the cellulose of Berzelius' paper, 

 act in precisely the same way in manure heaps. The aerobic 

 fermentation of cellulose is carried on by moulds, by fungi 



