SOIL FUNGI 251 



1. Cells not forming at once a surface membrane on sugar media: 



(a) Ascospores having a single membrane, cells not fusing in 



pairs before formation, spore germination by ordinary 

 budding. Saccharomyces. 



(b) Ascospores having two membranes. Saccharomycopsis . 



2. Cells forming a surface membrane at once on sugar media: 



Ascospores lemon shaped or with pointed ends. Willia. 

 The presence of yeasts in the soils of orchards and vineyards 

 has been established by Hansen 56 and others. Wine yeasts 

 have been found in such soils even at a depth of 20 to 30 cm. 

 below the surface, but not at 40 cm. depth. 67 Soils rich in 

 humus, such as peat soils, offer a favorable habitat for these 

 organisms. 68 The greatest number of yeasts isolated from 

 the soil 59 are wild yeasts, including also white and red species 

 of Torula. An examination of eighty-seven soils from dif- 

 ferent parts of the United States revealed the presence of 

 yeasts only in forty-five per cent of the soils; only two soil 

 samples gave more than one species. 60 

 II. EUASCI, with ascogenic hyphae. This group is divided into a 



number of subgroups, some of which contain some important soil 



forms. It is sufficient to mention: 



1. DlSCOMYCETES, 



2. Plectoascineae, containing the genera Aspergillus and Pcni- 



cillium. 



3. Pyrenomycetineae. These contain the following 2 common 



soil genera: 



(a) Chaetomium* 1 (No. 94, PI. XIV). Various species of 



this genus have been isolated from the soil by Jensen, 

 Traaen, Waksman and others. 



(b) Sordaria and various other ascomycetes (Sporormia) 



have frequently been isolated from the soil. 



66 Hansen, E. C. Experimental studies on the variation of yeast cells. Ann. 

 Bot., 9: 549-560. 1895. Neue Untersuchungen fiber den Kreislauf der Hefen- 

 aften in der Natur. Centrbl. Bakt. II, 10: 1-8. 1903; 14: 545-550. 1905. 

 Compt. Rend. Trav. Lab. Carlsberg., 9: 61-69. 1911. 



67 Mliller-Thurgau, H. Nachweis von Saccharomyces cllipsoides im Wein- 

 bergsboden. Centrbl. Bakt. II, 14: 296-297. 1905. 



68 Lemmermann, Fischer, et al., 1909 (p. 260). 



69 Klocker, A. Deux nouveaux genres de la famille des saccharomycetes. 

 Compt. Rend. Lab. Carlsberg., 7: 273-278. 1909. De Kruyff, E. Unter- 

 suchungen uber auf Java einheimische Hefearten. Centrbl. Bakt. II, 21: 616- 

 619. 1908. 



60 Starkey, R. L., and Henrici, A. T. The occurrence of yeast in soil. Soil 

 Sci., 23: 33-46. 1927. 



61 Chivers, 1915 (p. 251). 



