COPRINUS STERQUILINUS 197 



the form of a hollow cylinder. The hollow space within is of con- 

 siderable size. Passmg down its centre from the disc is a loose 

 string of hyphae which is well shown in the photograph reproduced 

 in Fig. 73 (p. 184) but which has been omitted in the drawings 

 in Fig. 97 (p. 232). A similar string of hyphae is to be found in 

 the hollow stipe of Coprinus comatus, to which G. sterquilinus is 

 so closely related. 



At first the stipe is white. Its lower haK remains white ; but, 

 whilst elongating and just before the expansion of the pileus, its 

 upper half becomes reddish owing to the development of a red 

 colouring matter in the cell-sap of its outer hyphae. This pigment 

 gradually darkens in colour and becomes very dull brown. The 

 result is that the upper part of the stipe comes to have a blackened 

 appearance. The blackening of the upper part of the stipe 

 which is shown in Figs. 72 (p. 184), 76 (p. 187), and 100 (p. 236) 

 is a normal phenomenon and not due to accident. I emphasise 

 this point because Massee,^ Rea,^ and other systematists erro- 

 neously state that the stipe turns black on being bruised. I 

 have attempted several times to make the stipe go black by 

 bruising it, but have always failed. There are Agarics which 

 rapidly change colour when bruised, and many such are known 

 among the Boleti ; but Coprinus sterquilinus is not one of 

 them. 



The shaft of the stipe, partly on account of its hollowness, is 

 fragile : it appears to have its substance reduced to the utmost 

 degree consistent with the carrying out of its supporting function. 

 The extreme base of the shaft and the solid stipe-base are peronate, 

 i.e. densely clothed with fine white projecting hyphae. In a small 

 fruit-body which came up spontaneously on horse dung the 

 diameter of the solid part of the stipe-base was found to be ' 9 cm., 

 but the diameter of this solid part plus the hairy coat on its exterior 

 was 1*3 cm. 



At the base of the pileus, when this is still barrel-shaped and 

 unexpanded, there is a ring of sterile tissue surrounding the stipe. 



1 G. Massee, " A Revision of the Genus Coorinus." AnnaU of Botany, vol. x, 

 1896, p. 139. 



^ Carleton Rea, British Basidiomycetae, Cambridge, 1922, p. 500. 



