io 4 RESEARCHES ON FUNGI 



A fully expanded fruit-body of Pleurotus ulmarius, when 

 confined in a large beaker in the laboratory, was observed by the 

 beam-of-light method to shed spores for seventeen days continu- 

 ously. During the last few days the gills gradually turned mouldy. 

 Since the fruit-body appeared to be of full size and expansion when 

 gathered, it seems probable that, had it been left to continue its 

 existence under natural conditions, its spore-fall period might have 

 exceeded three weeks. 



Coprinus comatus sheds spores from the moment "deliquescence" 

 begins at the base of the gills until these have disappeared. For 

 some large specimens, growing in a field under favourable weather 

 conditions, the spore-fall period was found to last about two days 

 and two nights. Smaller species of Coprinus, such as C. plicatilis, 

 shed their spores in a few hours. 



The continuous discharge of spores for days or weeks is certainly 

 a remarkable fact which requires further elucidation from the point 

 of view of development. It must be remembered in this connection 

 that adjacent basidia in most fruit-bodies are in very various stages 

 in regard to the production of spores. The fact that after the spores 

 on a basidium have attained their full size and final colour, they 

 remain on the sterigmata but a very short time, seems to show that 

 they are discharged as soon as ripe. There must be some means by 

 which a succession of developing basidia on any given part of the 

 hymenium is provided. Possibly the discharge of spores from one 

 basidium serves as a stimulus for the development of one or more 

 neighbouring basidia. It is certain, however, that the process is 

 beautifully regulated, for thus only could a Polyporus squamosus, 

 a Lenzites betulina, or a Polystictus versicolor give out millions of 

 spores in such steady streams for many days without interruption. 



