128 RESEARCHES ON FUNGI 



dioxide, whilst the third was set in a chamber containing ordi- 

 nary air. Glass slides were employed to catch any spores which 

 might fall. 



The piece of pileus in air shed abundance of spores, a good deposit 

 outlining the gills being collected in the short space of ten minutes. 

 A thick deposit had formed in an hour, and in the course of twenty 

 hours tens of thousands of spores had collected. The piece of pileus 

 placed in hydrogen shed a few spores during the first hour. At the 

 end of this time it was removed to a new position on the glass slide. 

 During the subsequent nineteen hours scarcely a spore fell. The 

 few spores found on the slide with the microscope certainly did not 

 make up one five-hundredth part of the number which fell from the 

 piece of pileus placed in air. A similar result was obtained with 

 the piece of pileus placed in carbon dioxide. During the first 

 hour in that gas a few spores were liberated. The piece of pileus 

 was then pushed to a new position on the glass slide. During 

 the subsequent nineteen hours practically no further spores became 

 deposited. 



The conclusion to which the experiments just described appear 

 to point is that, in the absence of oxygen, spore-discharge soon 

 ceases. Doubtless for some time after a piece of pileus has been 

 placed in hydrogen or carbon dioxide, the basidia have access to 

 a certain amount of oxygen diffusing outwards from the pileus 

 through the hymenium. Possibly it is on this account that a few 

 spores still continue to be liberated for a short time after the 

 oxygen has been removed from the surrounding atmosphere. We 

 may conclude by analogy that the direct action of hydrogen on the 

 pileus is harmless, but that that of carbon dioxide may possibly be 

 poisonous. 



Removal of oxygen from the atmosphere probably causes cessa- 

 tion of growth of the basidia. With this cessation of growth 

 the fall of spores must cease, for the continuous raining down 

 of spores from the gills depends on the successive development of 

 the basidia. 



Two small pilei, one of Marasmius oreades and the other of 

 Psilocybe fcenisecii, were halved. One piece of each was covered by 

 a glass vessel containing air, and the other pieces were placed in a 



