194 BUTYRIC ACID FERMENTATION. 



effect of both species is necessary, an enzyme being then excreted 

 which dissolves the cellulose. Van Senus isolated this enzyme, 

 and demonstrated its solvent power on cellulose by applying the 

 alkaline solution (containing chloroform in order to suppress bac- 

 terial growth) to the cell walls of slices of beans. 



V. OMELIANSKY (I.), in 1895, obtained very different results. 

 He inoculated a mineral nutrient solution (containing potassium 

 phosphate, magnesium sulphate, ammonium sulphate, and chalk), 

 in which strips of Swedish filter-paper were held in suspension, 

 with a small quantity of mud from the Neva, and then kept the 

 whole at 3o-35 C., air being excluded. Fermentation rapidly 

 set in, the strips of paper gradually becoming thinner and finally 

 disappearing altogether. By repeated transferences of small por- 

 tions of the fermenting liquid to fresh sterile media the ferment 

 was purified, and finally brought into a state of pure culture by 

 anaerobic cultivation on discs of boiled potato. Omeliansky de- 

 scribes the organism as an unusually slender bacillus, measuring 

 only 0.2 to 0.3 ft in breadth for a length of 6-7 /A, and forming 

 terminal globular endospores i //, in diameter, whereby the pole at 

 which the spore occurs is swollen up. 



As in many other directions, here also, in the case of the 

 fermentation of cellulose, the extension of our knowledge is de- 

 pendent on the elucidation, still to be made by chemists, of the 

 composition of the substances subjected to investigation for the 

 products they yield on fermentation. At the present time the 

 essential requirement that the ferment shall be used in a state of 

 pure culture is almost fulfilled, but so far as the purity of the 

 cellulose to be decomposed is concerned matters are by no means 

 on a satisfactory footing. ERNST SCHULZE (I.) in 1895, in a treatise 

 setting forth the present state of our knowledge on the subject 

 (and one well worthy of perusal) shows how very divergent are the 

 substances which now bear the name of " cellulose." He separated 

 a number of these, and collected them into the group of hemi- 

 celluloses, distinguished by their solubility in hot dilute mineral 

 acids whereby they are converted into glucose, whilst the remain- 

 ing celluloses do not undergo this change. Considering how 

 divergent these substances are, it is not surprising that different 

 investigators do not always obtain concordant results as regards 

 the products of cellulose fermentation. This decomposition occurs 

 on a large scale in the mud of marshes where there is no lack of 

 decaying plants, and where, moreover, the other conditions are 

 favourable. It has long been known to chemists that, in such 

 water, a somewhat copious discharge of gas bubbles rises out of the 

 ground, which discharge consists for the most part of methane 

 (CH 4 ), i.e. the gas to which the name of marsh-gas has been given 

 from the places where it is found in Nature. Carbon dioxide is 

 also liberated at the same time. The proportional quantity of the 

 two products was reported in several analyses communicated by 



