48 RESEARCHES ON FUNGI 



22|- hours. Probably the actual length of the period did not exceed 

 18 hours. 



There is no doubt that the fruit-bodies of Psathyrella disseminata 

 are very ephemeral. Every field mycologist knows that they die 

 down within 24 hours of stretching their stipes and expanding their 

 pilei. The short period of existence of the mature fruit-bodies 

 is evidently strictly correlated with the brief duration of the spore- 

 discharge period. A fruit-body of a fleshy Agaric is of no value 

 whatever to the species to which it belongs when once it has shed 

 its spores, and there would be nothing gained, and there would be a 

 good deal lost, if it were provided with materials for prolonging its 

 existence after its usefulness was over. As one might therefore 

 expect, on the ground of economy, the gills of a fruit-body which 

 has just shed its last spores are practically exhausted of their 

 contents. The individual cells of the hymenium, subhymenium, 

 and trama no longer contain any massive contents. The proto- 

 plasm, if present, is in the form of an extremely attenuated layer 

 lining the cell- walls, and in each cell it surrounds one huge vacuole. 

 It is no wonder that such an exhausted fruit-body soon dies, col- 

 lapses, and becomes a prey to saprophytes. The death of the fleshy 

 fruit-bodies of Hymenomycetes, almost immediately after spore- 

 discharge has ceased, finds its parallel in the withering of the corolla 

 of the Lady's Slipper Orchid very shortly after the pollination of 

 the stigma has taken place, and also in the death of many insects 

 very soon after their contribution to the propagation of the species 

 has been made — the males after they have effected the fertilisation 

 of the females, and the females after they have completed the laying 

 of their eggs. 



It is important to grasp the central fact of the ephemeral nature 

 of the fruit-bodies of Psathyrella disseminata, for only by so doing 

 shall we understand the delicate structure of the fruit-body as a 

 whole and the organisation of the hymenium, which are strictly 

 correlated with it. 



The Gills. — The gills are acutely wedge-shaped in cross-section 

 in the unexpanded fruit-body and they look downwards toward 

 the earth when the spores are being liberated, in the manner shown 

 for Lepiota cepaestipes in Fig. 5 (p. 12). Moreover, every part of 



