198 



RESEARCHES ON FUNGI 



When the stipe begins to elongate, this ring of tissue may remain 

 attached to the peronate stipe-base, thus forming an adnate sheath 



or volva (Figs. 70, p. 181, and 83), 

 or it may be carried upwards on 

 the base of the pileus for some dis- 

 tance and then, as the pileus begins 

 to expand, be set free and dropped 

 upon the stipe so as to form a 

 loose annulus (Figs. 72, 74, 75, 

 82, pp. 184, 185, 186, 195). In the 

 fruit-body shown in Fig. 71 (p. 182) 

 the annulus is still being carried 

 upwards on the base of the pileus, 

 while in that shown in Fig. 97, C 

 (p. 232), it has only lately been 

 dropped upon the stipe. The 

 annulus of Coprimis coynatus is 

 formed in the same manner as that 

 of C. sterquilinus, but in C. coma- 

 tus it never remains below and 

 therefore never forms a volva : it 

 is always carried by the base of 

 the pileus some way up the stipe- 

 shaft and then set free. It may 

 be asked why it is that in Coprinus 

 sterquilinus sometimes a volva 

 is formed and sometimes a free 

 ring. It is not unlikely that the 

 answer to this question is to be 

 found in the effect of external con- 

 ditions : it may be that very 

 moist conditions are favourable to the formation of a looser ring of 

 tissue which may be readily pulled upwards over the stipe so that 

 eventually it becomes converted into an annulus, while drier con- 

 ditions may result in the formation of a more tightly fitting ring 

 of tissue which cannot be readily pulled upwards over the stipe 

 and which, therefore, when the stipe begins to elongate, must be 



Fig. 83. — Coprinus sterquilinus. 

 A very small fruit-body with 

 the annulus left as a volva on 

 the base of the stipe. The 

 pileus has begun to expand. 

 Natural size. 



