ORDER SACCHAROMYCETALES 345 



each, at the two ends of the ascus. The spores are needle-shaped, tapering 

 at one end to a slender flagellum-like thread which is not motile. Sexual 

 union of two cells to produce the ascus has been claimed for N. lycopersici 

 Schneid. by Schneider (1916), by Wingard (1925) in A'^. phaseoli Wing., 

 and in N. coryli Peglion by Miss Manuel (1938), but is denied by Guillier- 

 mond (1928). Probably closely related to this genus is Ashbya gossypii 

 (Ashby & Now.) Guill. which causes injury to the bolls of cotton {Gos- 

 sypium). It differs in having a very limited yeast stage, mainly developing 

 a coenocytic, variously branching hypha, one end of which, without a 

 separating septum, functions as the ascus. Guilliermond claims that the 

 nuclei functioning in the ascospore development do not arise from the 

 division of one original ascus nucleus but by the division of several nuclei 

 already present in that portion of the 

 hypha. Both Nematospora and Ashbya 

 are apparently spread by the punc- 

 tures of various sucking insects. The 

 genus Eremothecium is very similar to 

 Ashbya. E. ashbyii Guill. (1936a) was, 

 like it, isolated from diseased cotton 

 bolls. It differs chiefly in the slightly 

 different form of the ascospores. In . Fig. 115. Saccharomycetales, Fam- 

 , , i 1 . 1 ily Saccharomycetaceae. Saccharo- 



several respects these three genera ,„^^^^^^ ;^^^,„-^.. Hansen. (A) Ascus 



suggest the gametophytic generation with four ascospores. (B) Conjugation 



of Spermophthora gossypii Ashby & of ascospores by twos. (C) Zygotes 

 --. ,, ,.,.,. Ill germinating to form new diploid cells. 



Nowell, which IS discussed below (Courtesy, Guilliermond: Ann. fer- 

 (under Family Sperm ophthoraceae). mentations, 2:129-151, 257-277.) 

 (Fig. 115.) 



Monosporella bicuspidata (Metschn.) Keilin, parasitic in Daphnia (a 

 Crustacean), and Coccidiascus legeri Chatton, parasitic in a species of the 

 fly Drosophila, have similar ascospores and possess a budding yeast-like 

 stage. They probably are closely related to the foregoing genera. 



The intensive studies by Miss Stelling-Dekker (1931) upon the large 

 collection of yeasts in the Centraalbureau voor Schimmelcultures in 

 Baarn, Netherlands, have led her to the conclusion, already expressed by 

 Van Tieghem in 1906, that the distinction between the three families En- 

 domycetaceae, Saccharomycetaceae, and Schizosaccharomycetaceae can- 

 not be maintained and that they must be united under the older name 

 Endomycetaceae with the four subfamilies Eremascoideae, with the 

 single genus Eremascus; Endomycoideae, containing Endomyces and 

 Schizosaccharomyces; and Saccharomycoideae, with Endomycopsis and 

 most of the sporogenous genera of yeast habit; and Nematosporoideae. 

 This scheme of classification was adopted by Guilliermond (1936b) in a 

 contribution in which the various genera are discussed and illustrated. 



