SPOROBOLOMYCES 203 



As we have seen, Sporobolomyces yeast cells sometimes produce 

 two, three, or four sterigmata instead of one only. Such yeast cells 

 are curiously reminiscent of disterigmatic, tristerigmatic, and tetra- 

 sterigmatic basidia of the Hymenomycetes. 1 Guilliermond's 2 

 illustration of a cell of S. salmonicolor in which there are four sterig- 

 matic tips each crowned by a conidium has the appearance of a 

 grotesque hymenomycetous basidium. If Sporobolomyces is of 

 hymenomycetous origin, the production of 2-4 sterigmata by some 

 of the yeast cells may be due to an inherited tendency to develop 

 a typical unicellular basidium. 



Monosterigmatic basidia are by no means unknown in the 

 Hymenomycetes. 3 They have been observed, for instance, by others 

 in species of Pistillaria and by myself in Coprinus bisporus and the 

 cultivated form of Psalliota campestris. In the hymenium of the 

 last-mentioned fungus monosterigmatic basidia are commonly 

 found mixed with the more numerous disterigmatic basidia (vide 

 Vol. II, Figs. 105, 143, 146, and 147 on pp. 314, 409, 416, and 429). 

 The fact that, as a rule, Sporobolomyces yeast cells only produce 

 a single sterigma need not therefore prevent anyone who wishes to do 

 so from regarding the yeast cells as equivalent to reduced basidia. 



Whereas in the Hymenomycetes and the Uredineae, as my own 

 observations on living basidia have shown, 4 each basidium produces 

 only one crop of spores and then collapses, so that each sterigma 

 gives birth to but a single spore, in Sporobolomyces each yeast cell 

 normally produces on the end of one and the same sterigma several 

 conidia (2, 3, or 4 or possibly more) in succession (Fig. 90, p. 182). 

 This arrangement, which is unknown in any of the typical Basidio- 

 mycetes, saves the yeast cell from the burden of producing several 

 sterigmata and, at the same time, makes it possible for the yeast 

 cell to produce several spores each as large as itself. It is certain 

 that, whilst producing its succession of conidia, a yeast cell is 

 absorbing food materials and building up new protoplasm in its 



1 For variations in the number of sterigmata and spores produced by Hymeno- 

 mycetes vide these Researches, Vol. II, 1922, pp. 315-321. 



2 A. Guilliermond, loc. cit., p. 251, Fig. 4. 



3 Monosterigmatic basidia in the Hymenomycetes are treated of in these 

 Researches, Vol. II, p. 315. 



4 These Researches, Vol. II, pp. 27-29. 



