42 



RESEARCHES ON FUNGI 



(A). This lower part of the disc-flesh grows both radially and 

 tangentially, whereas the upper part of the disc-flesh does not. 

 Owing to this differential mode of growth of the disc-flesh (c/. A, 

 B, and C), the collar at the top of the gills (D, c) is gradually turned 

 outwards and upwards, the gills leave the stipe and become turned 

 through a right angle into horizontal positions, a naked zone of 

 bare flesh 0- 5-2-0 mm. in width (D, 6) comes to surround the stipe 



Fig. 25. — Coprinus plicatilis. Vertical sections showing three stages in the dev^elop- 

 ment of a fruit-body, drawn semi-diagrammatically, to show how the growth 

 of the pileus-flesh brings about the expansion of the pileus. A : the gills are 

 vertically disposed, and they are black owing to the presence of ripened spores ; 

 the pileus is slightly umbonate ; the pileus-flesh is about to raise the gills. 

 B : the under part of the pileus-flesh between the gills and the stipe is growing 

 radially and is thus expanding the pileus. C : the under part of the pileus- 

 flesh between the gills and the stipe has now grown radially to its maximum 

 extent and has thereby completely expanded the pileus ; the disc is now 

 depressed ; the inner ends of the gills are widely separated from the stipe ; 

 and spore-discharge is about to begin. D : view of the middle part of the 

 expanded pileus of C seen from below ; a, the stipe ; b, a bare area of pileus- 

 flesh between the gills and the stipe ; and c, a collar formed by the union of 

 the inner ends of the gills. The change from A to C took place in a single 

 morning. Enlarged to 1 • 33 the natural size. 



below and to separate the stipe from the gill-collar, and the disc of 

 the pileus, as viewed from above, becomes depressed (C). 



Marasmius rotula (Fig. 26), another small agaric, found on 

 sticks, resembles Coprinus plicatilis in its general form. It, too, 

 has a sheath of flesh surrounding the top of the stipe in the un- 

 expanded pileus, a very decided gill-collar, a pileus which is convex 

 when expanded, and a disc which becomes depressed. The ex- 

 pansion of the pileus in this species appears to take place in the 

 same manner as that just described for Coprinus plicatilis. 



The pileus of Coprinus plicatilis, when just fully expanded and 

 seen from above, is date-brown at the depressed disc and elsewhere 

 greyish or cinnereous, owing to the fact that the black spores are 

 seen collectively through the translucent flesh and through the 



