218 



RESEARCHES ON FUNGI 



One of the chief functions of the stipe is undoubtedly to provide 

 a space usually one or more inches high between the under surface 

 of the pileus and the substratum on which the fruit-body may grow. 

 Owing to the very small rate of fall of the spores and the relatively 

 very much greater average horizontal speed of air-currents near the 

 ground, the space is amply sufficient, under normal conditions, to 

 permit of the falling spores being carried away from the fruit-body 

 and deposited at a distance from it. 



Richard Falck 1 has put forward the theory that the fruit-bodies 



FIG. 7<i. Semidiagrammatic sketch of a section in a field illustrating the manner in 

 which the spores of the Horse Mushroom (Psalliota arvensis) are liberated and 

 dispersed. A slight lateral movement of the air is supposed to be carrying the 

 spore-cloud away from the underside of the pileus. Reduced to . 



are themselves specially adapted to produce air-currents for the 

 purpose of scattering the spores. His theory is founded on the fact 

 that fruit-bodies, when insulated, become distinctly warmer than the 

 surrounding atmosphere. In one of his experiments, he found that 

 the hy menial tubes of Polyporus squamosus, placed thickly together 

 in a carefully insulated chamber for ten hours, became 9 - 6 C. 

 warmer than similarly situated hymenial tubes which had previously 



1 " Die Sporenverbreitung bei den Basidiomyceten und der biologische Wert 

 der Basidie," Beitriige zur Biologie der Pflanzen, Bd. IX., 1904, p. 1. 



