EARLY OBSERVATIONS 329 



From his work, he concluded that cellulose undergoes a fer- 

 mentation in the first stomach of ruminants and in the alimentary 

 canal of all herbivora. In later work he tried to decide whether 

 this fermentation was due to an organized or to an unorganized 

 ferment. This he did by inoculating suitable flasks with the 

 contents of the alimentary canal of oxen. The flasks were divided 

 into three sets and treated as follows: (1) Heated, (2) treated 

 with antiseptics (thymol and the like) and (3) untreated. Fer- 

 mentation occurred only in the last set from which he concluded 

 that it was due to bacterial action. From his work in general 

 he decided that bacteria have the power of decomposing cellulose 

 with the formation of carbon dioxid and methane and that this 

 process plays a large part in the digestive processes of herbivorous 

 animals. 



Hoppe-Seyler, who considered the fermentation process mainly 

 from the changes which take place when cellulose is decomposed 

 in soil or beneath water, commenced his experiments by collecting 

 and analyzing the gases given off from soils and swamps. These 

 he found to consist mainly of carbon dioxid and methane. Later 

 he carried out laboratory determinations by placing 25.773 grams 

 of filter paper into 1000 c.c. flasks containing 700 c.c. of water and 

 inoculated with mud. They were so arranged that the gaseous 

 products were collected over mercury. He incubated them at 

 room temperature for four years. During the first year there was 

 considerable gas evolved, but the evolution gradually became 

 slower until at the end of four years the evolution of gas had practi- 

 cally ceased. An analysis showed that 15 grams of the cellulose had 

 been decomposed with the formation mainly of carbon dioxid 

 and methane. He was unable to find any of the true sugars, 

 although he thought it possible that there were some of the dextrin 

 compounds in the solution. When air was excluded he found 

 that there was a greater production of methane and a smaller one 

 of carbon dioxid. From his work he considered the reaction pro- 

 ceeded in two stages: First, a hydration of the cellulose with 

 the formation of a hexose according to the equation, C 6 Hi 5 + 

 H 2 O -> C 6 Hi 2 O 6 . From the hexose, carbon dioxid and methane 

 was formed (C 6 Hi 2 O 6 - 3C0 2 + 3CH 4 ), or perhaps acetic acid 

 was an intermediate product and then carbon dioxid and methane 

 were formed according to the equation, CH 3 COOH -> C0 2 + CH 4 . 



In 1889 Schlosing published his quantitative results of the 

 investigation on the decay of manure. He collected the gases 

 given off in the course of two months in the decay of manure and 

 analyzed them. He concluded that the change was similar to 

 alcoholic fermentation. 



Three years later the work of Herbert appeared. He inoculated 

 5 per cent, solutions of potassium carbonate or ammonium car- 



