BASIDIA AND THE DISCHARGE OF SPORES 



Size and Rate of Growth of the Water-drop. 



At the moment when a spore is suddenly shot away from its 

 basidium, so far as I have been able to observe, there is no 





* A A A 



4^^ ^^J ^^ ^^3 



FIG. 5. Psalliota campestris. Diagrammatic representation showing the 

 discharge of four spores in rapid succession from a basidium as seen 

 from above. The dotted circles show the positions of spores which 

 have been shot away. The spores are discharged in order according 

 to their numbers 1, 2, 3, and 4. The times of each stage, taking the 

 stage A as the zero of the time scale, are approximately as follows : 

 B, 2 seconds ; C, 7 seconds ; D, 7 seconds ; E, 10 seconds ; F, 10 seconds ; 

 G, 13 seconds; H, 13 seconds ; I, 16 seconds ; and J, 16 seconds. Thus 

 all the spores are shot away in a quarter of a minute ; but the dis- 

 charge is rarely so rapid as this. Magnification, 1,320. 



contraction of the basidium as a whole. Even when all four spores 

 have just been discharged, the basidium appears to have just as 

 large and turgid a body as before discharge began (cf. Fig. 4). It 

 is evident that the spores are not squirted away from the basidium 

 by the basidium-body contents and, therefore, that the mechanism 

 of discharge is not analogous to that employed for the discharge 

 of spores from the explosive asci of the Ascomycetes or for the 

 discharge of the sporangium from the sporangiophore of Pilobolus. 



For some time after beginning to observe the excretory pheno- 

 menon in connection with spore-discharge, I was puzzled as to 

 what becomes of the drop at the moment when the spore is shot 



