OEDER SACCHAROMYCETALES 337 



resent derivatives of entirely different orders or even classes of fungi which 

 have evolved into yeast-like forms. Under certain conditions of culture 

 yeast-like cells are formed by some Mucorales, Ustilaginales, and many 

 families of Ascomyceteae. Although their true relationships are doubtful 

 they are given consideration here. Apart from these are two families that 

 possess sexual reproduction and a simplicity of structure that implies 

 either great reduction or, on the contrary, a great degree of primitiveness: 

 the Spermophthoraceae and Pericystaceae. Their relationships are very 

 doubtful. Their consideration in this chapter is due to a lack of conviction 

 on the part of the author as to where else they might more properly find 

 their relationship, rather than because of any evident kinship with the 

 Saccharomycetales. 



The first two families to be discussed are those that are normally 

 filamentous and ascus-producing. 



Family Endomycetaceae (Including Eremascaceae of Some 

 Authors). Typically forming a branched mycelium with the cells uninu- 

 cleate or containing several nuclei. Asexual reproduction by the breaking 

 up of branches of the mycelium into " oidia" or by the formation of bud- 

 ding branches. Some species are capable of alcoholic fermentation. Sexual 

 reproduction takes place by the union of projections of usually (but not 

 always) adjacent cells to form an ascus perched upon the tips of the united 

 processes. In some cases the gametangia are distinctly a small antherid 

 terminal to a slender antheridial branch and a large oogone. In some 

 species the two processes do not unite or even only one is produced so that 

 the ascus is formed parthenogenetically. Ascospores are eight or four or 

 less, frequently fewer. They are ellipsoidal or hat-shaped. 



Eremascus fertilis Stoppel and E. albus Eidam produce eight asco- 

 spores after the union of the tips of adjacent cells which may be tightly 

 coiled around one another in the latter species. Frequently union fails to 

 occur and the parthenogenetically produced asci contain four or fewer 

 ascospores. The mycelium produces no conidia (either oidia or budding 

 cells). Endomyces is distinguished from Eremascus by the production of 

 four or fewer ascospores per ascus and by asexual reproduction by means 

 of oidia. Endomycopsis differs from both by the production of budding 

 cells as well as occasionally of oidia. In both genera ascus formation may 

 be parthenogenetic or may be the result of the union of two equal or 

 unequal gametangia. Some species of both genera are able to ferment 

 various sugars but some lack this power. Endomycopsis albicans (Vuill.) 

 Dekker has been found in cases of the disease of the mouth known as 

 thrush although this mostly seems to be due to an asporogenous filamen- 

 tous yeast. The various other species of the two genera are found in soil 

 and on various vegetable products. It must be noted that these two 

 genera are very close to the true yeasts and possibly the distinction be- 



