i68 RESEARCHES ON FUNGI 



times produce spores but are more or less parasitised. The sub- 

 stance of the pileus appears to be least affected and is not greatly 

 thickened in the plants observed. The mycelium of the parasite 

 causes the greatest deformation in the stem and the fruiting bodies 

 are produced from the apex of the stem." 



Since the fruit-bodies of Coprinus sterquilinus, although smaller, 

 resemble those of Coprinus comatus so closely, I thought it might 

 be possible to parasitise them with Stropharia epimyces, and there- 

 fore made the following experiments. I (1) sowed large numbers 

 of fresh spores of Coprinus sterquilinus and Stropharia epimyces 

 together on sterilised horse dung in a large crystallising dish, (2) sowed 

 spores of the Stropharia on the mycelial strands and very young 

 fruit-body rudiments of the Coprinus, and (3) inserted spores of 

 the Stropharia into the very young pilei of the Coprinus. How- 

 ever, none of the Coprinus sterquilinus fruit-bodies which developed 

 showed the least sign of having been infected by the parasite, for 

 no fruit-body became distorted and all of them shed their spores in 

 a normal manner. Thus my attempts to parasitise Coprinus ster- 

 quilinus with Stropharia epimyces obtained from Coprinus comatus 

 completely failed. It would be of considerable interest to find out 

 experimentally, if one could, at what stage of development the 

 fruit-bodies of Coprinus comatus and of C. atramentarius become 

 invaded by the mycelium of the Stropharia, and also exactly how 

 the mycelium of the parasite is related to its host. 



How did the parasitism of Stropharia epimyces upon species of 

 Coprini originate ? Our answer, of course, can only be speculative- 

 There appear to be three possibilities : 



(1) It is possible that at first the Stropharia, like other Stro- 

 phariae, lived as a pure saprophyte on dead organic matter of 

 various kinds, that it then became specialised to feed on large dead 

 agarics — just as, at the present time, Collybia tuherosa and C. cir- 

 rhata feed on dead Russulae, Lactarii, Hydna, etc., in the woods 

 at Gimli on Lake Winnipeg and at Kenora on the Lake of the Woods 

 — and that, having taken to a diet of agarics, by some alteration 

 in its excretions it became adapted to grow on living agarics 

 instead of dead ones. This theory would well explain the 

 origin of the parasitism of Hypomyces lactifluorum on Lactarius 



