VARIOUS OBSERVATIONS 59 



America on Lactarius, especially upon Lactarius piperatus. Since 

 first becoming acquainted with the parasitised agaric at Winnipeg, 

 I have found it in considerable numbers at Gimli on Lake Winnipeg, 

 at Kenora on the Lake of the Woods, and at Minaki and White 

 Dog upon the Winnipeg River in Western Ontario. I have fre- 

 quently observed it in company with Lactarius piperatus, and a 

 comparative study of the two fungi in the woods has convinced 

 me that in Central Canada the host plant of the Hypomyces is 

 usually, if not always, Lactarius piperatus. My observations on the 

 host-species of the Hypomyces thus confirm those of Mcllvaine. 1 



The fruit-bodies of Lactarius piperatus are attacked by the 

 Hypomyces before they come above the ground, and it is possible 

 that they are infected when extremely small and young. The time 

 and mode of infection are as yet unsolved phytopathological 

 problems. Although many of the infected Lactarii retain their 

 symmetry of form (Figs. 17 and 18), others exhibit more or less 

 irregularity, their stipes being abnormally thick, and their pilei 

 excentric and contorted. 



Lactarius piperatus, when parasitised by the Hypomyces, not 

 only has the development of its gill-system inhibited but also its 

 hymenium, so that is is rendered perfectly sterile. It produces 

 no basidiospores whatsoever and yet its general vigour seems to be 

 in no way diminished. Its fruit-bodies, although often misshapen, 

 have a massive appearance and its pilei are not infrequently 

 4-5 inches in diameter, i.e. as large as those of the largest 

 unparasitised fruit-bodies. A comparison of parasitised and un- 

 parasitised fruit-bodies even gives the impression that the former 

 have the thicker flesh and the greater weight. When a tangential 

 section is cut through the side of the pileus, one sees near the lower 

 even edge a wavy line of tissue which, doubtless, is a trace of 



1 I have never found Hypomyces lactifluorum in England cr met with any one 

 who has. It is not mentioned by C. B. Plowright in his Monograph of the British 

 Hypomyces (Grevillea, vol. xi, 1882). However, at King's Lynn in three successive 

 seasons, Plowright found a yellowish-green Hypomyces, H. luieo-virens, which, 

 like H. lactifluorum, attacks agarics before they appear above the ground and so 

 alters its hosts that it is difficult or impossible to determine their species. Karsten 

 (vide Plowright, loc. cit., p. 1) says that he found H. luteo-virens on Lactarii in 

 Finland. Presumably, this fungus, which I have not seen, like H. lactifluorum, 

 inhibits the development of the gills of its host. 



