SPOROBOLOMYCES 173 



that the yeast cells in all stages of their development contain but 

 a single nucleus and never exhibit karyogamy, so that in this respect 

 they differ from typical basidia ; and he concluded : (1) that there 

 is no cytological justification for placing the Sporobolomyces yeasts 

 in the Hemibasidii ; (2) that these yeasts deserve a special place 

 in the classification of fungi ; and (3) that their affinities are still 

 unknown. 



In 1930, Derx * divided the yeasts which produce and violently 

 discharge conidia into two genera, Sporobolomyces and Bullera ; 

 and he placed these genera in a new family which he called the 

 Sporobolomycetes . The species included in Sporobolomyces, S. albo- 

 rubescens, S. gracilis, S. odorus, S. roseus, S. salmoneus, S. salmoni- 

 color, and S. tenuis, are rosy, red, or flesh-coloured and have reniform, 

 sickle-shaped, or pyriform spores which are asymmetrical ; whereas 

 the species included in Bullera, B. alba and B. grandispora, are 

 colourless, creamy, yellowish, or brownish, without any trace of 

 red, and have rounded, ovoid, or globular spores which are 

 symmetrical. 2 Sporobolomyces salmoneus in culture gave rise to a 

 colourless mutation, S. salmoneus var. albus. Several species are 

 markedly mucilaginous, but this character may disappear in culture. 

 As a means for differentiating and determining the known species 

 of Sporobolomycetes, Derx has provided a key. 3 



Among Derx's 4 general observations on the Sporobolomycetes 

 are the following. The Sporobolomycetes are very widely distri- 

 buted in nature and they are essentially epiphyllous. They occur 

 on damaged leaves, on straw, on grains of wheat, etc., and on stems 

 covered with sugary exudations ; and, in particular, they are 

 nourished by honey-dew. Consequently, they are often in the 

 company of leaf-parasites and of sooty moulds such as Dematium 

 pullulans and Cladosporium herbarum. To obtain species of Sporo- 

 bolomycetes in culture one has only to suspend moist leaves or 



1 H. G. Derx, " Etude sur les Sporobolomycetes," Annates Mycologici, 

 Vol. XXVIII, 1930, pp. 1-23, Plate I. 



2 The spores of both Sporobolomyces and Bullera develop asymmetrically on 

 their sterigmata (cf. this Chapter, Fig. 90, nos. 2-5). The terms asymmetrical and 

 symmetrical, as employed by Derx, refer to the shape of the mature spores detached 

 from their sterigmata. 



3 H. G. Derx, he. cit., pp. 20-21. 4 Ibid., pp. 2-5, 22. 



