BIOCHEMICAL ACTIVITIES OF SOIL FUNGI 435 



concerned in these important changes, when, as a matter of fact, 

 soil fungi are also vitally concerned in these processes. An at- 

 tempt will be made to show that these fungi function in three in- 

 terrelated ways: (1) in decomposing carbohydrates, (2) in am- 

 monifying proteins, and (3) in producing mineral transformations. 



Decomposition of carbohydrates. Both simple and complex 

 carbohydrates are now known to be fermented by various fungi. 

 It may be recalled that Hoppe-Seyler (1886) long ago secured 

 evidence that filter paper is digested in the presence of a little 

 sewage slime. He placed 25.773 grams of filter paper in a flask, 

 so constructed that he could lead off the gases for analyses. After 

 4 years 15 grams of the cellulose had been digested, with the pro- 

 duction of 3281 cc of carbon dioxide and 2571 cc of methane. 

 This decomposition was established to be induced by anaerobic 

 bacteria. Evidence that fungi can also function in the decomposi- 

 tion of cellulose was first presented by van Iterson (1904) in 

 1904. His experiments were performed not with pure cultures 

 but with soil as inoculum. The medium consisted of filter paper 

 moistened with tap water in which small amounts of ammonium 

 nitrate and monopotassium phosphate had been dissolved. By this 

 procedure evidence was secured to show that certain fungi, includ- 

 ing Chaetommm kunzeanum, Trichocladium asperum, Stachy bo- 

 try s altemans, Sporotrichum bomby cinum, S. roseolum, S. griseo^ 

 lum, Botrytis sporoideiim^ My co gone pnccinioides, and Clado- 

 sporhim herbarum, digest cellulose. Van Iterson's observations 

 initiated a series of studies on cellulose digestion by fungi, among 

 them those by Kellerman and AIcBeth (1912), Daszewska (1913), 

 Scales (1916), Waksman (1918), and Henkelekian and Waksman 

 (1925). Kellerman and McBeth (1912) made use of cellulose 

 agar, the preparation of which they describe, and established that 

 many species of Aspergillus, Fusarium, Penicillium, and Sporo- 

 trichum utilize cellulose as nutrient in pure cultures. Daszewska 

 (1913) found that Sporotrichum olivaceum, Verticillium glau- 

 cum, V. celhdosae, and various other Hvphomvcetes are more 

 important in cellulose decomposition than are bacteria and that 

 the color of the humus formed is related to that of mycelium and 

 conidia. Among 22 species of soil fungi tested by Waksman 

 (1916), 15 were able to decompose cellulose. 



Henkelekian and Waksman (1925) have shown that Tricho- 

 derma and Penicillium possess the ability to decompose cellulose 



