346 CLASS ASCOMYCETEAE 



It seems likely that this tentative scheme may in the future form the best 

 basis for the classification of the sporogenous yeasts and near relatives. 

 Further cytological studies are desirable before this can be considered as 

 entirely settled. 



The Asporogenous Yeasts are those in which no formation of asci is 

 known. Since it has been demonstrated by Lindegren and Lindegren 

 (1943) and suggested by others, also, that races of species of the genus 

 Saccharomyces may lose their power of ascus production, probably as a 

 result of some gene mutation, the distinction between the two groups is 

 very doubtful as regards some genera. 



Family Nectaromycetaceae. This very doubtful family contains the 

 single genus Nectaromyces named by the Sydows (1918). This fungus 

 grows in the nectar of flowers and is easily cultivated. It produces yeast- 

 like budding cells in abundance, but under certain conditions produces a 

 cluster of four cells cruciately arranged or "airplane-like." Also long 

 branched hyphae may occur, which bear conidia at their tips. 



Family Torulopsidaceae. The members of this family are in the 

 main quite similar to the yeasts of the Saccharomycetaceae but differ 

 from them in the complete absence of ascus formation. As mentioned 

 above this may be due in some cases to gene mutations in sporogenous 

 yeasts. On the other hand it must be borne in mind that yeast-like cells 

 are produced under the proper conditions of environment and nutrition 

 in such widely distinct fungus orders as the Mucorales, Ustilaginales, and 

 some of the Heterobasidiae and Eubasidiae, besides various species of 

 different orders of the Ascomyceteae. Hence it is conceivable that this 

 family may be of heterogeneous origin. Many of the species are capable of 

 fermenting various sugars with production of CO2 and alcohol or related 

 substances; others can oxidize the sugars in the presence of oxygen but do 

 not cause fermentation. Many of the latter and a few of the former are 

 pathogenic in Man and other animals. Following Lodder (1934) and 

 Diddens and Lodder (1942) the family is divided into two subfamilies: 

 Torulopsoideae, in which no mycelial stages occur and Mycotoruloideae, 

 in which mycelia or pseudomycelia occur, from which at the apex or along 

 the hypha budding takes place. Besides this the fungus may grow as 

 simple budding cells. 



In the Torulopsoideae Lodder recognizes seven genera of which Toru- 

 lopsis and Pityrosporum may be mentioned. Torulopsis is known in medi- 

 cal literature more commonly as Torula or as Cryptococcus and sometimes 

 as Blastomyces. The name Torula properly belongs to a genus of filamen- 

 tous fungi of the Family Dematiaceae of the Fungi Imperfect!. On that 

 account Berlese proposed, according to Lodder, the name Torulopsis in 

 1894 for the yeast-like, asporogenous organisms to which the other names 

 are so often given. The species of this genus resemble those of Saccharo- 



