lo RESEARCHES ON FUNGI 



tiiining the turgidity of the cl'11. The gill of u Cojiri nit.s coiiLntafi 

 was L\id on a ghiss slide. On looking at one of the hymenial 

 surfaces from above with a microscope, I observed that, as the 

 gill began to lose water, the four sterigmata of each basidium 

 bent together so that the spores came into contact and adhered 

 to one another. The turgidity of the basidium is important 

 therefore in that it serves to keep the spores in their proper 

 positions in space. In dry weather, spores — which have a 

 relatively high ratio of transpiring surface to volume — lose water 

 rapidly, and a constant stream must flow to them through the 

 sterigmata in order to prevent them from collapsing.^ 



In hymenial cells destined to remain sterile, i.e., to become 

 paraphyses, the two original nuclei Avith which each is provided, 

 do not unite with one another, but remain small and show no 

 signs of special activity. It is conceivable that at first all the 

 hymenial cells have equal possibilities of development, but that 

 for some reason the hymenium becomes divided up physiologically 

 into small areas, in each of which only a single cell can develop 

 into a basidium. We might suppose that each basidium has a 

 sphere of influence and by its own development causes the cells 

 adjacent to it to remain sterile. The problem of the spacial 

 arrangement of basidia upon a hymenium seems to be essentially of 

 the same nature as that of the arrangement of gills, hymenial tubes, 

 or spines on pilci, or as that of the arrangement of leaves upon stems. 



The nature of the nuclear fusion in basidia is a matter which 

 is still under discussion. Dangeard - regards it as morphologically 

 and physiologically ecpiivalent to a sexual act, and this view has 

 been accepted by Brefeld.^ The union of the two nuclei — called 

 karyogamy — must lead to a doubling of the number of chromo- 

 somes. The reduction of the latter to one half — the number 

 which we may suppose characterises the nuclei of the mycelium 

 and of the non-basidial cells of the hymenophore — is in all 



» (J. Cliiip. XVI. 



^ Dangeard, " La sexualitt' cliez les Champignons," Eevue Scientijique, 5* serie, 

 T. IV., 1905. Abstract in Jiof. Gentrulh., Bd. CII., 1906, p. .378. 



^ O. Brefuld, Uiifirsiiilinnfjen an?: dan Ui'saintg chide dcr Mijcologie, Bd. XI\'., 

 1908, pp. i'4G-2rj(). 



