THE COPRINUS TYPE OF FRUIT-BODY 213 



with the extremely reduced flesh, we find that the long axes of 

 the gills are almost vertical when spore-liberation begins. This 

 arrangement reduces the strain on the flesh to a minimum. The 

 pileus simply presses downwards on the stipe. When the gills 

 have become vertical at maturity they are then closely packed 

 together throughout their entire length except for their extreme 

 lower ends, where the change of shape of the pileus from the 

 barrel form to the bell form has caused them to separate. It 

 would be quite impossible for spores to be liberated from the 

 long vertical gills throughout every part of their whole length 

 simultaneously as in the Mushroom, for the gills are too close 

 together. If wide spaces were provided between them, not only 

 would this necessitate a laro'e reduction in the number of the 

 gills, but a large number of spores would require to fall vertically 

 downwards between the gill-plates a distance of several centi- 

 metres. In that case, unless the gill-planes were quite vertical, 

 a considerable proportion of the spores would strike the hymenium 

 on falling, adhere there, and be wasted. Granted, therefore, that 

 the gills are closely packed and vertically extended at maturity, 

 it is obvious that a different arrangement for spore-liberation has 

 to be adopted to that found in the Mushroom. As a matter of 

 fact, as we have already seen, the Coprinus sheds its spores from 

 a narrow zone of spore-discharge which passes on each gill from 

 below upwards. At the zones of spore-discharge, the gills are 

 always sufficiently far apart (about 0*2 mm.) to permit of the 

 spores, when violently projected from their sterigmata, describing 

 the usual sporabolic paths unhindered. To enable the gills to 

 move apart from one another higher and higher up as the zones 

 of spore-discharge ascend upon them, the process of autodigestion 

 comes into play. This causes the removal of the spore-freed 

 portions of the gills and thus allows the fruit-body to gradually 

 open out and thereby separate the gills higher and higher up. 

 Without autodisjestion it would bo difficult to imajjine how the 

 necessary interlamellar spaces could be provided at the moving 

 zones of spore-discharge. Toward the end of the period of spore- 

 discharge, the much shortened gills become horizontally out- 

 stretched like those of a Mushroom. At this stage, the pileus 



