Soil Miciobiolog)' as an Independent Science 



23 



Most of the discussion following Omeliansky's work was concerned 

 with the question of purity of the cultures and with the uncertainty 

 as to whether aerobic or anaerobic bacteria were more important 

 and which group was the primary agent in cellulose decomposition. 

 Numerous studies demonstrated that a large number of fungi are 

 capable of decomposing cellulose. In fact, under certain conditions, 

 as in acid soils or in composts, fungi may be more important than 



Fig. 15. Charles Thorn made a detailed study of the tungus population of the 



soil; he is responsible for the identification of numerous soil organisms, notably 



members of tlie genera Penicillhim and Aspergillus. 



bacteria. Actinomycetes may also play an important part in cellu- 

 lose decomposition, especially in high-temperature composts. Even 

 protozoa may be able to transform cellulose. Considerable knowl- 

 edge of the aerobic bacteria capable of bringing about cellulose de- 

 composition was also obtained. The nature of the material, the 

 natiu-e of the soil or compost, and the conditions of decomposition, 

 especially aeration and temperature, determine which organisms will 

 attack the cellulose in soils, in peat bogs, in sewage, or in composts 

 of manures and \'arious plant materials. 



The work of Jensen, Goddard, Waksman, and others on the fungi 

 of the soil, which was followed later by the studies of Melin and 

 Rayner on mycorrhiza fungi; the studies of Krainsky, Conn, Waks- 

 man, and Curtis on the actinomycetes of the soil; and the work of 



