[9] Brown, P. E., “Mould action in soils,” Science, 1917, 46.

[10] Burgeff, H., “Die Wurzelpilze der Orchideen,” Jena. 1909.

[11] Bussey, W., Peters, L., and Ulrich, P., “Ueber das Vorkommen von Wurzelbranderregern im Boden,” Arb. Kais. Biol. Anst. Land- u. Forstw., 1911, 8.

[12] Butkevitch, V. S., “Ammonia as a product of protein transformations caused by mould fungi, and the conditions of its formation,” Recueil d’articles dedié au Prof. C. Timiriazeff, 1916.

[13] Butler, E. J., “An account of the genus Pythium and some Chytridiaceæ,” Mem. Dept. Agr. India, 1907, Bot. Ser. 5, 1.

[14] Christoph, H., “Untersuchungen über die mykotrophen Verhältnisse der Ericales und die Keimung von Pirolaceen,” Beihefte Bot. Centr., 1921, 28.

[15] Coleman, D. A., “Environmental factors influencing the activity of soil fungi,” Soil Sci., 1916, 2.

[16] Dascewska, W., “Étude sur la désagrégation de la cellulose dans la terre de bruyère et la tourbe,” Univ. Genève, Inst. Bot., 1913, S. 8.

[17] De Bruyn, H. L. G., “The saprophytic life of Phytophthora in the soil,” Meded. v. d. Landbouwhoogeschool Wageningen, 1922, xxiv.

[18] Dox, A. W., “Amino acids and micro-organisms,” Proc. Iowa Acad. Sci., 1917, 24.