NYCTALIS ASTEROPHORA 457 



Since (1) smaller or less vigorous fruit-bodies either produce no 

 gills at all or, if they produce gills, have an aborted hymenium, 

 basidial production being limited to exceptionally large and vigorous 

 fruit-bodies in which the chlamydospores are formed relatively late ; 

 since (2) all fruit-bodies, both large and small, normally produce 

 chlamydospores in abundance ; and since (3) the chlamydospores 

 germinate readily on the living pilei of the host-plant ; it seems 

 fairly certain that, under natural conditions in the open, Nyctalis 

 asterophora normally reproduces itself by means of its chlamydo- 

 spores, in this respect doubtless resembling Ptychogaster albus. 

 However, it also seems likely that the basidiospores. when formed 

 and disseminated, may still serve for the direct infection of new host- 

 plants, although, as yet, this supposition does not appear to have 

 been put to the test of actual experiment. The part played by the 

 oidia in the dissemination of the parasite, if any, is problematical. 



It is not without interest to consider Bref eld's work on Nyctalis 

 in the light of what we have recently been taught about sex in the 

 Hymenomycetes by Mile Bensaude,i Hans Kniep,^ and certain other 

 experimental cytologists.^ Basing our remarks on Bref eld's obser- 

 vations, we can say that on germination a basidiospore of Nyctalis 

 asterophora, like basidiospores in general, gives rise to a primary 

 mycelium, i.e. a mycelium (1) having nuclei in the haploid or 

 unpaired condition, (2) having simple cross-walls, and (3) producing 

 oidia ; and that, after a time, this primary mycelium gives rise to 

 a secondary one, i.e. a mycelium (1) having nulcei in the diploid or 

 paired condition, with conjugate nuclear division, (2) having the 

 cross-walls provided with clamp-connections, and (3) not pro- 

 ducing oidia. Since Brefeld's illustrations (Fig. 189, no. 1, p. 456) 

 clearly indicate that a single basidiospore of N. asterophora produces 

 a mycelium which, without any other mycelium, soon develops 



1 Mathilde Bensaude, Recherches sur le cycle evolutif et la sexualite chez les Basidio- 

 mycetes, Nemours, 1918, pp. 1-189. 



^ Hans Kniep, " Uber morphologische und physiologische Geschlechtsdifferen- 

 zierung," Verhandl. der Physikal.-med. Gesellschaft zu Wilrzhurg, 1919, pp. 8-16. 



^ The problem of sex in Hymenomycetes will be dealt with somewhat fully in 

 vol. iv of these Researches. For British papers on the subject, vide Irene Mounce : 

 (I) " Homothallism and the Production of Fruit-bodies by Monosporous Mycelia 

 in the Genus Coprinus," Trans. Brit. Myc. 8oc.,\o\. vii, 1921, pp. 198-217; (2) "Homo- 

 thallism and Heterothallism in the Genus Copriiius," ibid., 1922, pp. 256-269. 



