THE VIOLENT PROJECTION OF SPORES 143 



distance above the plane of the hymenium, so that the basidia 

 are just out of view, one finds that spores spring into view and 

 immediately disappear again. This proves conclusively that the 

 spores have been projected violently upwards from the sterigmata. 

 The fine adjustment screw of the microscope was carefully cali- 

 brated by the glass plate method, and it was then found by measure- 

 ment with it that in the case of Coprinus plicatilis the spores 

 were projected upwards, so that they came into view in a plane 

 O08-O12 mm. above the plane of the spores on the sterigmata. 



It has been found possible to observe the upward projection of 

 spores in the Mushroom, and also in a species of Psilocybe. In 

 these cases, however, observations can only be made with consider- 

 able difficulty. In the ,Coprini the spores in a zone parallel with, 

 and adjoining, the deliquescing gill edge are all being discharged 

 almost simultaneously (Plate II., Fig. 12). The gills of Coprini are 

 also very thin and allow ample light to pass through them. In 

 all other species of Agaricinese, however, the spores are discharged 

 irregularly over the whole surface of a gill and there is no special 

 region of activity. Adjacent basidia are in very various stages of 

 development. When one looks down on a piece of gill of one of 

 these fungi, one but rarely sees the spores disappear from a basidium. 

 This is due to the fact that the ripe basidia are relatively far apart. 

 The gills are also much thicker than in the Coprini and allow but 

 little light to pass through them. 



The observations on the Mushroom were carried out in the 

 following manner. A fresh specimen was obtained from a field 

 and part of one of the pink gills placed flat in a closed compressor 

 cell. The latter was then placed on the stage of the microscope 

 and this tilted to an angle of about 45. The tilting ensured that 

 if a spore was shot off a sterigma in the field of view, it would 

 remain longer in view than it would if the microscope were vertical. 

 A plane situated a short distance above the hymenium was focussed 

 so that one could not see any of the basidia distinctly. After 

 several hours of watching, on three separate occasions a spore was 

 clearly seen to come into view in the plane above the hymenium 

 and to travel a little way across the field of view before disappearing. 

 The only explanation of these observations seems to be that the 



