COPRINUS ATRAMENTARIUS 279 



at e in Fig. 117 (p. 276), break down, become fluid, and disappear. 

 Doubtless, the destruction of the cell-walls is due to enzymes 

 liberated by the dying cells. The zone of autodigestion, which has 

 come into existence in the manner just explained, then gradually 

 ascends and destroys each gill from below upwards. The zone of 

 autodigestion follows hard after the zone of spore-discharge but 

 never invades it, for it restricts its destruction to the zone which has 

 become free from spores. 



After autodigestion has begun, five zones can be distinguished 

 in succession from above downwards on each gill within half a 

 millimetre of, and parallel to, its edge : 



(1) a zone of basidia with ripe spores, 



(2) a zone of spore-discharge, 



(3) a zone of spore-free surface, 



(4) a zone of autodigestion, and 



(5) a zone containing the products of autodigestion at the gill- 



edge. 

 These five zones, which are all shown in Fig. 120 (p. 281), keep 

 their relative distances unaltered ; and they gradually move up- 

 wards so that, in the course of about 48 hours, they involve the 

 whole of each gill. The gradual destruction of the gills from below 

 upwards and their disappearance is shown in the series of drawings 

 A, B, C, and D, reproduced in Fig. 118 (p. 278). 



The pileus shown in vertical section in Fig. 119 has opened out so 

 that its upper surface is now almost flat ; its rim is slightly revo- 

 lute ; and its gills have become reduced by autodigestion from below 

 upwards to less than one quarter of their original size. The spores 

 being discharged from the zones of spore-discharge at the gill-edges 

 cannot be distinguished owing to their excessively minute size but, 

 at the time the photograph was taken, some hundreds of thousands 

 of them, and possibly more than a million, must have been carried 

 away by the wind from beneath the pileus every minute. The 

 spore-stream of an active pileus is represented diagrammatically 

 in Fig. 113 (p. 269). 



The discharge of the spores from the individual basidia of Co- 

 prinus atramentarius takes place in the same manner as that already 

 described for other Coprini and the Hymenomycetes generally: 



