Abstract
The author has examined the assimilation of nitrogen on the basis of different sources of nitrogen and the secretion of nitrite to the substrate by some soil fungi. The following species of thermophilic and thermophilous fungi have been investigated: Malbranchea pulchella Saccardo et Penzig var. sulfurea Miehe, Humicola lanuginosa (Griffon et Maublanc) Bunce. Sporotrichum thermophile Apinis, Thielavia sepedonium Emmons, Paecilomyces varioti Bainier, Aspergillus fumigatus Fresenius, A. terreus Thom.