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 the 

 mushroom. It can be used conveniently with the xerophytic fruit 

 bodies of Lcnzitcs betuUna, Polystictus versicolor, Schizophyllum com- 

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

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

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

 discharge continues for some days. 



Ordinarily, spore discharge from any fruit body is a continuous 

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

 spores ceases quickly, demonstrating that oxygen is necessary. Ether 

 and chloroform act similarly to the gases above mentioned. The 



X A B 



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

 ium of a mushroom Agaricus (Psalliola) campeslris. X, The basidium with four 

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

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



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

 discharged successively, each spore being shot out violently by the 

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

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

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

 horizontal microscope and a revolving drum to record accurately the 

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

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

 and the progress of desiccation of the spores. Buller found the relatively 

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

 of 0.37 mm. per second while the relatively large spores of Amanitopsis 

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



