116 C. D. Sherbakoff 



A stroma, in the sense employed here, 30 is the fungous layer on which 

 aerial structures (aerial mycelium, conidiophores, and spores) are pro- 

 duced. The stroma may consist of more or less loose hyphse, or it may 

 form a dense pseudoparenchymic (plectenchymic), continuous sheet, 

 fleck, or prominent wart. There are often produced also roundish, more 

 or less wrinkled, often shiny, bodies, resembling true sclerotia. They 

 are of a dark blue color, and among the Fusaria studied in the course 

 of this work they were observed only in certain species of the section 

 Elegans; though according to Wollenweber (1913 a: 32) they are very 

 common also in the section Roseum, and are characteristic for one species, 

 F. sclerotium Wr.> of the section Gibbosum. 



METHOD OF STUDY AND PRESENTATION 



The method actually employed in this work consisted in the cultivation 

 of pedigreed strains of the various organisms on various natural and 

 artificial media. Almost without exception, all the strains were trans- 

 ferred to a new medium on the same day and the whole set of cultures 

 was kept under the same environmental conditions. In all important 

 cases duplicate cultures were employed. For the inoculum, as far as 

 possible, similar material was used — that is, only mature spores or 

 only aerial or only submerged mycelium. The importance of the same 

 environmental conditions for a comparative study is evident. It applies 

 equally as well to the kind of inocula used, as it was found 31 that often 

 an inoculation made with spores tends to better spore production, and 

 an inoculation with mycelium often results mainly, at any rate at first, 

 in the production of mycelium. 



In order to bring all cultures to the same stage of maturity and also 

 to assure their purity, dilutions in poured plates were made again and 

 again for the entire set of the Fusaria (of isolations made by the writer, 

 as well as of the organisms obtained in culture from other sources), and 

 then new transfers were made from colonies about two days old pro- 

 duced in the plates. 



In the macroscopical examination of the culture, special attention was 

 given to the presence or the absence, and the character, of aerial mycelium; 

 to the kind of fructification layer (pionnotes-like, sporodochial, and so 

 forth); to the color of spores, of aerial and submerged mycelium, and of 



30 A slightly different definition of stroma is given by Wollenweber (1913 a : 24, footnote). 



31 See Appel and Wollenweber (1910 : 13), and also Lewis (1913 : 209). The same was frequently found 

 to be the case also in the course of this work. 



