i66 RESEARCHES ON FUNGI 



the natural size, is shown (1) a normal unparasitised fruit-body of 

 Coprinus comatus. Then proceeding from left to right are shown : 

 (2) two fruit-bodies which are parasitised by the mycelium of Stro- 

 pharia epimyces and which in consequence are umbilicate and 

 stunted in appearance, (3) a similar fruit-body with two fruit-bodies 

 of the parasite appearing at its apex as white balls, and (4) another 

 similar fruit-body from the top of which protrude two fruit-bodies 

 of the parasite which are fully developed and are shedding spores. 



In Fig. 66, a little less than natural size, is shown a cluster of 

 about twenty fruit-bodies of Stropharia epimyces springing from the 

 tops of several large but very much stunted and more or less umbili- 

 cate living fruit-bodies of Coprinus cornMus. The photograph illus- 

 trates extremely well the success which the parasite has in mastering 

 its host-plants. The hosts, after being attacked by the mycelium 

 of the parasite, never elongate their stipes or open their pilei. 

 Moreover, although the gills sometimes produce spores, the spores 

 are never liberated, so that the parasitised fruit-body contributes 

 nothing to the reproduction of the species. There can be no doubt 

 that the stunted growth of the Coprinus is largely due to starva- 

 tion, in that the food materials, collected by the mycelium of the 

 Coprinus and normally destined to find their way into the Coprinus 

 spores, are abstracted from the host fruit-body by the mycelium 

 of the Stropharia and are used to construct the fruit-bodies and 

 spores of the parasite. 



The structure of Coprinus atramentarius fruit-bodies parasi- 

 tised by Stropharia epimyces has been thus described by E. T. 

 Harper : ^ 



" In plants which are parasitised, the elongation of the stem is 

 inhibited and the enlarged gill chambers lie obliquely upward with 

 their mouths outward in the position which they have in the fully 

 expanded carpophore of a mushroom of which the pileus becomes 

 obconic or infundibuliform. Thus is formed the top-shaped mass 

 of the host plant shown in the illustration " (c/. Figs. 65 and 66). 



" The substance of the veil which is left near the base of the 

 stem in normal plants becomes greatly thickened and enlarged 

 and covers the mouths of the gill chambers up to the margin of the 

 * E. T. Harper, loc. cit., vol. viii, pp. 70-71. 



