260 PRINCIPLES OF SOIL MICROBIOLOGY 



it was, therefore, concluded that the grubs and earthworms are the car- 

 riers of spores of soil fungi. 79 It is interesting to note that Takahashi 

 isolated the species Zygorhynchus molleri and Trichoderma koningi in 

 Japan at lower depths, while just below the surface he found Aspergilli, 

 Penicillia, and other organisms, like Mucor racemosus, Stemphylium, 

 and Chaetomium. 



In addition to the more than GO genera of fungi reported to be found 

 in the soil, probably as many more could be demonstrated, but to a 

 comparatively more limited extent. Our methods are not sufficiently 

 developed as yet as to allow the direct isolation of certain organisms like 

 the Basidiomycetes. The presence of a certain organism in large 

 numbers need not indicate its great abundance in the soil, but may be 

 due to abundant spore formation or to local development. Repeated 

 isolation of an organism from different soils and from various parts of 

 the same soil is essential, before any claim can be laid to its active part 

 in soil transformations. 



Activities of fungi in the soil. Fungi require for their development the 

 following elements: C, H, O, N, K, P, Mg, S, Fe. They obtain these 

 either from organic or from inorganic (outside of carbon) sources. 

 This points to their role in the soil, where they take part in at least two 

 important processes: (1) rapid decomposition of complex organic 

 substances; (2) assimilation of soluble inorganic nitrogen compounds and 

 minerals, especially in the presence of available energy, thus removing 

 them temporarily from the soil solution. The addition of fresh stable 

 manure rich in straw, of green manures, and of other plant residues to the 

 soil greatly stimulates the development of fungi ; the nature of the organ- 

 isms developing most abundantly depends to a large extent upon the 

 constituents of the organic matter added. The addition of stable manure 

 was found to stimulate the development of Penicillia and especially of 

 Mucorales and of actinomyces. 80 The -addition of pure cellulose, 

 especially in the presence of available nitrogen, brings about an extensive 

 development of various fungi, such as Trichoderma, Fusaria, Verti- 

 cillia, Monosporia, certain Penicillia, and other cellulose decomposing 

 organisms. The reaction of the soil, the moisture content, and the 

 nature and amount of the available nitrogen greatly modify the types of 

 fungi developing in the soil as a result of the addition of celluloses or 

 cellulose-rich materials. Plant substances are commonly added to the 



"Rathbun, 1918 (p. 259). 



80 Lemmermann, O., and Fischer, H., Kappen, H., and Blanck, E. Bac- 

 teriologisch chemische Untersuchungen. Landw. Jahrb., 38: 319-364. 1909. 



