56 RESEARCHES ON FUNGI 



plicatilis either at the time its fruit-body took on its present peculiar 

 form or subsequently thereto. In inaequi-hymeniiferous fruit- 

 bodies which before spore-discharge begins do not open like a 

 parasol, especially those with large gills, e.g. those of C. comatus, 

 C. atramentarius, C. picaceus, C. niveus, and C. stercorarius, the loss 

 of autodigestion would be disastrous to the functional efficiency of 

 the pilei, for the undigested portion of the gills would certainly 

 prevent the great majority of the spores from ever escaping into 

 the outer air. On the other hand, in C. plicatilis, owing to the 

 parasol-like opening of the pileus before spore-discharge begins, 

 the small depth of the gills, and the spUtting of the gills from above 

 downwards so that in expanded pilei they are Y-shaped in cross- 

 section, the loss of autodigestion in respect to the liberation of the 

 spores is of much less importance. The hymenium on the upper 

 split portion of each gill, like that on the soUd wedge-shaped gills 

 of the Aequi-hymeniiferae, everywhere looks downwards and, on 

 this account, all the spores which it bears can be Uberated without 

 any mechanical hindrance whatever. The unsplit parallel-sided 

 lower portion of each gill, although ageotropic and therefore not 

 in possession of any means for placing itself in a vertical plane, is 

 nevertheless situated almost in a vertical plane, owing to the nega- 

 tively geotropic reaction of the stipe which sets the whole pileus 

 in a horizontal plane and therefore all the gills in almost vertical 

 planes. In an expanded pileus the interlamellar spaces are very 

 broad and the unsplit portions of the gills are not much more than 

 1 mm. high. If the lower half of each gill in an expanded pileus 

 is not quite vertical, so that one side looks slightly upwards and the 

 other side shghtly downwards, the side looking downwards can 

 discharge its spores so that they all escape from the fruit-body. 

 The side looking upwards is at a disadvantage : if it looks upwards 

 only very slightly, some or possibly nearly all its spores will be able 

 to escape from the fruit-body ; but, if it looks upwards in a greater 

 degree, only a few spores near the margin of the gill will escape and 

 the rest of the spores, after being shot into the air, will fall back on 

 to the gill and stick there. In the field, in the afternoon, one often 

 finds exhausted fruit-bodies with some of the gills powdered black 

 on one of their two sides, and this doubtless is due to the want of 



