COPRINUS STERQUILINUS 



187 



few of the gills become entirely divided toward the rim of the pileus 

 into two separate halves. The pileus thus becomes torn into rays 

 (Figs. 98, 99, 100, pp. 234 and 236). 



The pileus-fiesh, frcm which the gills are developed in the first 

 place and to which they 



remain attached during the : 



production and liberation of 

 the spores, consists of a very 

 thin layer external to the 

 gills and of a cap just above 

 the top of the stipe. The 

 thin layer external to the gills 

 becomes split up into radial 

 ribbons during the expansion 

 of the pileus and the partial 

 splitting of the gills down 

 their backs. The flesh which 

 forms the disc of the pileus 

 is sufficiently thick and rigid 

 to provide an apparatus for 

 raising the weight of the 

 sides of the pileus during the 

 period of expansion. 



The gills, as a rule, are 3 

 to 6 mm. broad and 2*5 to 

 5 cm. long. They are at first 

 quite white, then reddish 

 owing to the development 

 of the already-mentioned cell-sap in eveiy cell, and finally 

 purplish-black owing to the browning of the red cell-sap and to 

 the formation of a very dark brown pigment in the walls of the 

 spores. The colour-changes take place from below upwards on 

 each gill (c/. Fig. 97, C, p. 232). 



The shape of the gills in cross-section is shown in Fig. 78. The 

 two sides of a gill are not quite parallel but are slightly con- 

 vergent from the flesh to the free margin ; but the free margin, 

 instead of ending sharply as in Psalliota cavipestris, Marasmius 



Fin. 



70. — C'oprinus sterquilinus. An ex- 

 panding pileus. Tlie sulcations are 

 caused by each gill splitting into two 

 halves part of the way down its 

 median plane. The stipe has become 

 tinged with black. Natural size. 



