242 



RESEARCHES ON FUNGI 



basidiospores derived from mycelial mats like that shown in Fig. 114, 

 C (p. 232). The secondary basidiospores were then fixed and stained 

 with iron-alum haematoxylin. In every secondary basidiospore of 

 the Tilletiae and of the Entyloma investigated there was one nucleus 

 only and never two (Fig. 117). 



A separation of nuclei, comparable with 

 that which takes place when a primary 

 basidiospore of Tilletia tritici germinates 

 has been found by Bauch x in Ustilago 

 longissima and its variety macrospora and 

 by Dickinson 2 in Ustilago laevis and U. 

 hordei. They observed that, after two 

 haploid hyphae have conjugated and two 

 nuclei of opposite sex have become asso- 

 ciated in the same cell, when this cell pro- 

 duces sporidia the nuclei of opposite sex 

 separate again, one going into one sporidium 

 and the other into another sporidium, so 

 that all the subsequent sporidia are uni- 

 nucleate and haploid. Gilmore 3 has ob- 

 served a similar phenomenon in Psilocybe 

 coprophila, one of the Hymenomycetes. 

 Here a diploid mycelium with clamp- 

 connexions gives rise to haploid uninucleate 

 oidia. Vandendries and Martens 4 have 

 recently found that, in Pholiota aurivella, 

 the diploid mycelium produces both haploid 

 and diploid oidia. 

 Abnormal Basidiospore-discharge. — When basidiospores are 

 developed in closed chambers in artificial cultures, they frequently 



1 R. Bauch, " Uber Ustilago longissima und ihre Varietat macrospora,'" Zeitschrift 

 f. Botanik, Jahrg. XV, 1923, pp. 241-279. 



2 S. Dickinson, " Experiments on the Physiology and Genetics of the Smut 

 Fungi.— Hyphal-Fusion," Proc. of the Roy. Soc., B, Vol. CI, 1927, pp. 126-135. 



3 K. A. Gilmore, " Culture Studies in Psilocybe coprophila,'''' Botanical Gazette, 

 Vol. LXXXI, 1926, pp. 419^33, Plates XXXII and XXXIII. 



4 R. Vandendries and P. Martens, " Oldies haploides et diploides sur Mycelium 

 diplo'ide chez Pholiota aurivella," Bull, de I Acad, roy.de Belgique, classe des Sciences, 

 T. XVIII, 1932, pp. 468^72. 



Fig 



117. — Tilletia tritici. 

 Secondary basidio- 

 spores (Bref eld's 

 secondary conidia) 

 from a mycelium like 

 that shown at D in 

 Fig. Ill (p. 226) or 

 at C in Fig. 130 

 (p. 260) stained with 

 iron - alum haema- 

 toxylin. There is only 

 one nucleus in each 

 spore. Magnification, 

 about 480. 



