COPRINUS STERQUILINUS 231 



Just before spore-discharge begins, the marginal gill-flange 

 (Figs. 78 and 79, pp. 189 and 191) beneath what is to become the zone 

 of spore-discharge {s in Fig. 97, E) undergoes autodigestion. It 

 breaks down, changing from a solid to a fluid condition ; and so it 

 contracts and disappears. This autodigestive removal of the lower 

 part of the gill-flange is very timely ; for, if the flange were to 

 remain in existence until the process of spore-discharge began, by 

 partially blocking the openings of the interlamellar spaces it would 

 undoubtedly prevent many of the spores from escaping from the 

 pileus. It is evident that the gill-flanges persist only so long as they 

 are of service to the fruit-body by helping to maintain the inter- 

 lamellar spaces during the development and ripening of the spores 

 and that, after the pileus has begun to expand, when they become 

 not merely functionless but also prospective mechanical obstacles 

 to the fall of the spores, they are at once destroyed. 



As soon as a narrow zone (about • 1 mm. wide) along the bottom 

 of each gill has become spore-free owing to spore-discharge from the 

 basidia, the process of autodigestion which, as we have seen, has 

 destroyed the gill-flange, involves this spore-free zone also. Each 

 gill has two opposite spore-free zones upon it, one on each side ; 

 and a band of the lower cells of the hymenium in both zones breaks 

 down, becomes fluid, and is thus removed. The subhymenial and 

 tramal cells between the two bands of hy menial cells suffer a like 

 fate, so that the whole substance of the gill in a transverse direction 

 becomes affected by the disintegrating process. All the gills are 

 subjected to this local destruction at the same time. 



The gradual change of the gills from the solid to the liquid 

 condition which has been known to mycologists as deliquescence 

 I have called autodigestion,^ for there is every reason to suppose 

 by analogy that the gill-tissues are destroyed by enzymes liberated 

 from the cell-sap of the dying cells. This view has been supported 

 by the observations of Weir ^ who found that the juice extracted from 

 a pileus of a species of Coprinus contains an enzyme which is able 

 to break down the walls of hyphae taken from the interior of the stipe. 



1 A. H. R. Buller, these Researches, vol. i, 1909, p. 200. 



- J. R. Weir, " Untersuchungen iiber die Gattung Coprinus," Flora, Bd. 103, 

 1911, p. 271. 



