334 CELLULOSE-DECOMPOSING ORGANISMS 



plex organic compounds which are fermented by other organisms 

 with the generation of large quantities of organic acids. These 

 would react with the minerals of the soil rendering them available. 

 This is very likely the cause of the good results obtained from raw 

 rock phosphate and stable manure on phosphorus-poor soil. The 

 fermentation of the cellulose yields acids which render soluble 

 the phosphorus. This formation of acids may at times, however, 

 become excessive, giving rise to the sour humus of moors and 

 heaths. 



It is well known that the fermentation processes in the soil 

 resulting in the decomposition of organic matter may give rise to 

 large quantities of carbon dioxid, methane and hydrogen. The 

 hydrogen and methane do not all pass into the atmosphere, but 

 according to the researches of recent investigators furnish energy 

 to numerous soil organisms, the importance of which remains 

 almost wholly for future workers to develop. The first work on 

 this subject was done by Immendorff, who in 1892 found that 

 hydrogen and oxygen may be made to unite under the influence of 

 soil. He found that the oxidation of hydrogen was brought about 

 only by normal soil and not by soil previously treated with chloro- 

 form vapor. This observation remained unnoticed until recently 

 when two papers appeared one by Kaserer and the other by 

 Solmgen which throw considerable light on this phase of carbon 

 and hydrogen transformation. They used an inorganic solution 

 containing dipotassium phosphate, ammonium chlorid, magnesium 

 sulphate, sodium bicarbonate, and a trace of ferric chlorid. This, 

 they inoculated with a small quantity of soil and confined in 

 an atmosphere consisting of a mixture of hydrogen, oxygen and 

 carbon dioxid. Growth took place and the hydrogen disappeared. 

 The presence of a small quantity of carbon dioxid seemed to be 

 necessary for the development of the organisms, and it would 

 appear that like the nitrifying bacteria they can produce bacterial 

 protein in inorganic solutions, deriving their carbon from carbon 

 dioxid. This reaction, according to Lipman, is of great significance 

 in agriculture, for a great loss of energy is prevented by the bacterial 

 oxidation of hydrogen formed in the deeper layers of the soil by 

 anaerobic ferments. It also partly counteracts the rapid minerali- 

 zation of organic materials, in that it leads to the formation of com- 

 plex compounds from carbon dioxid, hydrogen and oxygen. 



Kaserer and Solmgen also obtained organisms capable of utilizing 

 methane as the sole source of energy in their life process. The 

 latter investigator secured pure culture of an organism which he 

 named Bacillus methanicus. When grown in inorganic solutions 

 confined in an atmosphere of one-third methane and two-thirds 

 air, it caused the disappearance of the methane with the production, 

 of considerable quantities of organic material. 



