24 RESEARCHES ON FUNGI 



would be entirely wasted. Not a single basidiospore would be shot 

 up far enough to succeed in escaping from a Peziza cup ; whilst in 

 a Mushroom or Polyporus the ascospores, when discharged, would 

 strike and adhere to the opposite hymenial surfaces. An upwardly- 

 looking, Peziza-like, cup-shaped Hymenomycete, provided with 

 typical basidia and liberating its spores into the air, is just as 

 impossible as a Mushroom- or Polyporus-shaped Ascomycete with 

 its hymenium composed of typical explosive asci. Where, in the 

 Hymenomycetes, as in the genus Cyphella, the fruit-body has the 

 form of a saucer, a cup, or a filter funnel, with the hymenium 

 inside, its mouth looks not upwards but downwards, so that it 

 resembles an inverted Peziza. It is true that the conical wine- 

 glass-shaped fruit-bodies of the species of the hymenornycetous 

 genus Craterellus stand erect. Here, however, in contradistinction 

 to Cyphella, the hymenium is borne on the exterior of the fruit- 

 bodies, whilst the interior is barren. The position of the basidia of 

 a Craterellus is exactly the reverse of that of the asci in the 

 erect wine-glass-shaped fruit-bodies of certain Ascomycetes. These 

 remarks may serve to emphasise the close correlation between the 

 mechanism for spore-liberation and fruit-body structure. 



The Effect of Sunlight upon Spores. Some years ago, Massee l 

 expressed the view that the hymenium of the Hymenomycetes, 

 during progressive phylogenetic development, had come to be 

 placed on the lower sides of the pilei, instead of on the upper, 

 for the purpose of concealing it from the light. On the other 

 hand, my own researches seem to show that the position of the 

 hymenium has been primarily decided by the necessity of the 

 basidia being so placed that they can readily liberate their spores 

 into the air. Other, but subsidiary, advantages accruing to the 

 hymenium from its position on the lower side of a pileus, rather 

 than the upper, are: protection from rain, falling leaves, &c., and 

 undue transpiration in dry weather. 



The exact efl'eot of direct sunlight upon the spores of Hymeno- 

 mycetes still remains to be worked out. In the Clavanea3, many 

 species live in fields, &c., where their hymenial surfaces are freely 



1 G. Massae, " A Monograph of B.-itish Gastromycetes," Ann. of Bot., vol. iv. 

 1889, p. 2. 



