12 RESEARCHES ON FUNGI 



fertilisation ever occurs in any species of Hymenomycetes can 

 only be decided by extended observations. At present no Hymeno- 

 mycetes seem to be known which suggest that they are hybrids 

 produced from two individuals of distinct species. However, it 

 would be interesting to plant the spawn of several distinct varieties 

 of the cultivated Mushroom (Psalliota campestris) side by side in 

 beds of manure, and to observe whether or not under these con- 

 ditions any intermediate fruit-bodies would be produced. 



It seems probable that the original sexual organs of Hymeno- 

 mycetes — those corresponding to oogonia and antheridia in Asco- 

 mycetes — have disappeared, and that a new form of sexuality has 

 arisen by the fusion in the basidia of the descendants of what 

 were originally merely vegetative nuclei. 1 This view is supported 

 by the discovery of Miss Fraser, 2 that in Humaria rutilans, one 

 of the Ascomycetes, normal fertilisation by means of sexual organs 

 is replaced by the fusion of vegetative nuclei in pairs — a process 

 analogous to that which takes place in pseudapogamous fern pro- 

 thallia and also in the Uredineee. 



The Colour of Spores. — The colour of spores has long at- 

 tracted attention, owing to the fact that it has provided a useful 

 means of subdividing the Agaricinere. It must be admitted, 

 however, that the classification of this great group according 

 to spore colour is a purely artificial arrangement, although it 

 fulfils its primary object of enabling the student the more 

 readily to find the name of a particular species. There is no 

 good reason for believing that the Melanospone, the Porphyro- 

 spone, the Ochrospone, the Rhodosporre, and the Leucospone are 

 separate and distinct offshoots from a common stock, and this has 

 been fully recognised by Hennings in his treatment of the Agari- 

 cineru in Die natilrliehen Pflanzenfamilien of Engler and Prantl. 



1 The vegetative origin of the fusion nuclei in Hymenomycetes seems to be 

 generally accepted. Gf. N. Bernard, " Phenomcnes reproducteurs chez les Cham- 

 pignons superieurs," Bull, mens Assoc.fr. Annie Sc, 1905. Abstract in Bat. 

 Gentralb., Bd. CI., 1906, p. 394; Miss H. C. I. Fraser, "Nuclear Fusions and 

 Reductions in Ascomycetes," Brit. Assoc. Report for 1907, p. 688; also O. Brefeld, 

 1908, loc. tit., p. 256. 



2 Miss H. C. I. Fraser, "Contributions to the Cytology of Humaria rutilans," 

 Ann. of l^t., vol. xxii., 1908, p. A± 



