PANAEOLUS CAMPANULATUS 259 



those situated next to the dotted contour hues and the least ripe 

 those occupying the very middle of the drawing. For the black 

 central area, therefore, the development and order of spore- 

 discharge is centripetal. 



A study of areas like those represented in Figs. 89 and 90 

 leads one to the conclusion that the hymenium of a gill of Panaeolus 

 campanulatus is so organised that its development takes place in 

 a series of waves of small dimensions, which move irregularly and 

 simultaneously through it. 



The Spore-fall Period. By placing a series of pieces of white 

 paper under the pileus of a large specimen of Panaeolus campanu- 

 latus growing upon horse dung under a bell-jar in the laboratory, 

 and by observing the daily spore-deposits, it was found that the 

 period of spore-fall lasted for eleven days. As judged by the 

 blackness of the spore-deposits accumulated during each 24 hours, 

 the rate at which spores were given off attained its maximum 

 about the second or third day. Thereafter it slowly declined, 

 fewer and fewer spores being shed each day. The spore-deposits 

 for the first seven clays were all fairly dense, those for the next 

 three days very thin, and that formed on the last day only just 

 recognisable. On the twelfth day the stipe collapsed. By means 

 of a calculation, the details of which will be given in a subsequent 

 section, 1 the total number of spores which were liberated during 

 the whole spore-fall period was determined to be about 215,000,000. 

 Some other fruit-bodies were observed to shed spores for at least 

 a week. 



From the above observations it is clear that the spore-discharge 

 period lasts for a considerable number of days. Now if, during 

 any of the days when spores are streaming from the pileus, one 

 examines the hymenium of one of the gills, one observes that 

 everywhere it exhibits basidia bearing spores. The Figs. 89 and 

 90 would do to represent the hymenium for any of the first 

 four days of spore-discharge. From a consideration of these facts, 

 one can make an important deduction : as soon as one generation 

 of basidia on a black area has shed its spores, its place is at once 

 taken by another generation of basidia, which rapidly develops 

 1 The section called : " The Spores which are Wasted." 



