LIBERATION OF SPORES AND CONIDIA 113 



If the pileus of a white-spored Agaric is placed gills 

 downwards, and supported so that it rests about an inch 

 above a sheet of black paper, and then covered with a 

 bell-jar to prevent currents of air, it will be observed that 

 when the spores are shed, they cover a circle considerably 

 larger than that of the diameter of the pileus. This has 

 been considered as evidence that the spores of Agarics 

 are abjected or propelled to an appreciable distance. I 

 have not been able to satisfy myself on this point; the 

 difference between the temperature of the pileus and that 

 of the enclosed air in the bell-jar might account for 

 the diffusion of spores beyond the periphery of the 

 pileus. 



In Sphaerobolus stellatus, one of the Gasteromycetes, 

 the entire inner peridium, which is about the size of a 

 pin's head, is forcibly ejected, due to unequal tension of 

 the different layers of the outer peridium. I once had 

 a considerable quantity of this fungus under observation 

 for some weeks. It was covered by a bell-jar twelve inches 

 in diameter and eighteen inches high, and the inside of the 

 upper half of the jar was studded with the minute peridia 

 of the Sphaerobolus, which are covered with mucilage and 

 remain fixed to the object they strike. When a peridium 

 struck the glass, it could be heard in every part of the 

 room. There is also a very audible sound when the 

 outer peridium cracks to eject the spore-mass. There is 

 obviously a slip somewhere in De Bary's statement, that 

 in favourable cases the inner peridium of Sphaerobolus is 

 shot to a distance of more than a millimetre. Perhaps { a 

 metre ' was intended to be written. 



Consult the chapter on ' Dispersion of Spores,' which to 

 some extent covers the present chapter. 



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