2i 4 RESEARCHES ON FUNGI 



IV 



quires to be disc-shaped in order to permit the parts of the 

 gills nearest the stipe to obtain the requisite spaces for spore- 

 discharge between them. The very thin flesh is also now quite 

 sufficient to support the much reduced burden of the gills in the 

 horizontal position. 



During the process of spore-discharge, the stipe of Coprinus 

 comatus elongates considerably. It adds a number of centimetres 

 to its length and often becomes a foot long (Plate IV., Fig. 22). 

 As the fluid produced during autodigestion is gradually lost by 

 evaporation and dripping, the weight of the pileus, i.e. the load 

 which the stipe has to support, undergoes progressive reduction. 

 The higher the pileus can be raised with mechanical safety, the 

 better will be the chance of the spores escaping obstacles and 

 being carried off by the wind. It seems clear that the gradual 

 raising of the pileus by the elongation of the stipe is correlated 

 with the progressive diminution of the pileus weight. In the 

 Mushroom, on the other hand, the burden to be borne by the 

 stipe does not alter during spore-liberation. In keeping with this 

 we find that in this type of fruit-body the stipe attains its 

 maximum length before spore-discharge begins. 



If the Coprinus and the Mushroom types be compared, I 

 think it must be admitted that the former is superior to the 

 latter in producing the maximum number of spores with the 

 minimum of fruit-body substance and energy. A Coprinus fruit- 

 body with its extreme reduction of flesh, vertical position of the 

 gills, successive ripening of the spores from below upwards, and its 

 beautifully regulated autodigestion, may be thought of as having 

 been evolved from a more generalised fruit-body of the Mushroom 

 type, with thick flesh, horizontal gills, irregular ripening of the 

 basidia, and absence of autodigestion. The special features of a 

 typical Coprinus fruit-body are bound up with its umbrella shape. 

 It seems to me that only after this had been attained could the 

 special Coprinus arrangements have been developed and become 

 effective. For this reason I regard the genus Coprinus as having 

 been derived entirely from a fungus having fruit-bodies of the 

 Mushroom type with central stipe and a symmetrically-placed, 

 gill-bearing pileus. At the present day there are no Coprini with 



