BASIDIA AND THE DISCHARGE OF SPORES 17 



observations permit only of one inference and that is that the 

 drop excreted at the spore-hilum is carried by the spore in its 

 flight through the air. 



The carriage of a drop of water by every spore which has just 

 been discharged helps to account for the extraordinary adhesiveness 

 of hymenomycetous spores when they are newly liberated. They 

 stick to any surface which they happen to touch. After they have 

 settled, if the air is not saturated with moisture, owing to the very 

 small amount of water which they contain and have adherent to 

 them, they quickly dry up. Whilst drying they press themselves 

 more and more firmly to the substratum on which they lie. If 

 they have settled on a glass slide and have dried there, it often 

 happens that, if one attempts to remove them with a needle, they 

 do not come away without breaking. Probably, when a moist 

 spore settles on a glass slide, owing to capillary attraction, a little 

 water passes from the spore so as to lie between itself and the slide. 

 Assuming the existence of this water, it seems likely that, on its 

 evaporating, it drags down the smooth-coated spore to the slide in 

 such a manner as to flatten it out and thus to increase the area of 

 contact. 



Sometimes the excretion of water from the hilum takes place 

 in an abnormal manner. Several times I have noticed that, when 

 a gill of a Mushroom which has been kept under moist conditions 

 is mounted in air under a cover-glass, certain basidia which at the 

 ends of their sterigmata bear partly or fully grown yet immature 

 spores excrete water in abundance. The water arises from the 

 hila of the spores in the form of drops (Fig. 8, A). These at first 

 resemble the drops which are normally produced just before spore- 

 discharge, but they continue to increase in size until they meet and 

 fuse (B, C). One large drop is then held between the two young 

 spores (D). Finally, the drop becomes so large that it runs down 

 between the two sterigmata and disappears by moving on to the 

 surface of the hymenium. A* second instance of abnormal excre- 

 tion of water by a basidium is afforded by the following observa- 

 tion upon Lepiota cepaestipes. A transverse section was taken 

 through some gills and was mounted in water under a cover-glass. 

 The water, owing to the imprisonment of air, did not invade every 



