64 MYCOLOGY 



microscope by concentrating a beam of light upon them (Fig. 17) 

 This is a simple method of examining the discharge of spores from thi 

 mushroom. It can be used conveniently with the xerophytic frui 

 bodies of Lenzites hetulina, Polystidus versicolor, Schizophyllum com 

 mune at any time in the laboratory by keeping them dry for month 

 and reviving them by placing them in a jar with wet cotton. The} 

 quickly revive and begin to shed their spores in six hours and thi 

 discharge continues for some days. 



Ordinarily, spore discharge from any fruit body is a continuou 

 process, but if placed in hydrogen, or carbon dioxide, the liberation o 

 spores ceases quickly, demonstrating that oxygen is necessary. Ethe 

 and chloroform act similarly to the gases above mentioned. Th 



Fig. 18. — The successive and violent discharge of the four spores from the basii 

 ium of a mushroom Agaricus (Psalliotd) campeslris. X, The basidium with fo> 

 ripe spores; A, B, C, D, successive stages of the discharge of spores i, 2, 3, 4 respe 

 tively. (^After Butler, Researches on Fungi, 1909: 144.) 



special conidiophore, or basidium, usually bears four spores which ai 

 discharged successively, each spore being shot out violently by tl 

 pressure of the cell sap upon the wall of the basidium and perhaps aL 

 on the spore wall within a few seconds or minutes of one anothc 

 (Fig. 18). The rate of the fall was observed by BuUer, who used 

 horizontal microscope and a revolving drum to record accurately tl 

 rate of their fall. The rate of fall of the spores of gill fungi ranges fro 

 0.3 to 6.0 mm. per second. It varies with the size, specific gravii 

 and the progress of desiccation of the spores. B uUer found the relative 

 small spores of Collybia dryophila in dry air to fall at an average ra 

 of 0.37 mm. per second while the relatively large spores of Amanitop.s 

 vaginata in a saturated chamber attained a speed of 6.08 mm. p 



