328 CELLULOSE-DECOMPOSING ORGANISMS 



atmosphere has been known for a long time, but it was usually 

 thought of as passing from the solid complexes to the gaseous 

 compounds through its direct combination with oxygen at a high 

 temperature. In fact, this was considered as being the only 

 method until Pasteur pointed out that there were other means. 

 He considered it as being brought about by molds. Later Mit- 

 scherlich (1850) observed that when moist potatoes decay the cell 

 wall is dissolved and the starch gradually passes out. This he 

 thought to be due to a group of organisms, but nothing was done 

 to show that it was the work of any species until about fifteen 

 years later when Trecul isolated an organism which had the power 

 of decomposing young plant tissues and which was stained blue 

 by iodine. To this organism he gave the name amylobacter. 

 The organism he claimed had the power of decomposing cellulose 

 with the formation of butyric acid, carbon dioxid, and hydrogen. 

 As all of his work, however, was carried on with plant tissues, it 

 leaves a question as to whether the amylobacter had actually 

 decomposed cellulose or only some of the nearly related compounds. 



The decomposition of cellulose in manure was studied by Dehe- 

 rain, Gayon, Herbert and Popoff. The last investigator was the 

 first to recognize the similarity between the method of production 

 of methane in sewage and the intestines of animals. He studied 

 the action which took place when a medium containing Swedish 

 filter paper was seeded with sewage, and obtained a large volume 

 of gas, an analysis of which showed it to consist of carbon dioxid, 

 methane and hydrogen. The first two he thought to be due to 

 a cellulose ferment, but the latter to a butyric acid ferment. At 

 the end of the incubation period, there was a gummy mass in the 

 fermentation flasks. 



For a long time after this the attention of the investigators 

 seemed to be directed mainly to a quantitative study of the result- 

 ing products of fermentation. This is especially true with the 

 work of Tappeiner and Hoppe-Seyler. The former, with the idea 

 of determining the bacterial changes which take place normally in 

 the intestinal canal, introduced finely divided cotton or paper into 

 flasks containing a 1 per cent, neutral solution of beef extract. 

 The flasks and contents were sterilized and then inoculated with 

 small quantities of pancreatic juice and incubated at 35 C. They 

 were so arranged that the gases could be collected and analyzed. 

 The resulting product consisted of acetic acid, isobutyric acid, 

 acetaldehyd, methane and carbon dioxid. The last two were 

 in the ratio of 1 to 7.2 at the beginning of the process and 1 to 3.4 

 at the close. In another set of experiments he used an alkaline 

 medium and obtained the same qualitative but different quanti- 

 tative results, there being a large amount of hydrogen evolved in 

 the alkaline medium. 



