6 RESEARCHES ON FUNGI 



fresh horse-dung balls obtained from a stable are kept at 

 room temperature, the spores at once germinate ; and, within a 

 fortnight, the mycelium produces fruit-bodies. When horse-dung 

 balls fall on to the snow in the open during winter, they become 

 subjected to a temperature often ranging for some weeks from 

 15° C. to — 35° C. That this degree of cold does not injure the 

 spores is indicated by the fact that frozen dung-balls taken from 

 the streets of Winnipeg eventually produce large numbers of C. 

 curfus fruit-bodies. 



Pure cultures of Coprinus curtus (Figs. 3-5) were made in the 

 following manner. Some fresh horse-dung balls or pieces thereof 

 were [)laced in one-inch-wide test-tubes plugged with cotton-wool 

 or in small crystallising dishes covered with glass plates, and sterili- 

 sation was effected by setting the tubes and dishes in an autoclave 

 and subjecting them to steam at a pressure of 15 lb. for one hour. 

 Spores from a spore-deposit collected on a sterilised glass slide were 

 then sown on the surface of the dung. After about ten days, at 

 room temperature and in diffuse daylight, fruit-bodies began to 

 appear at the surface of the dung. 



The mycelium of Coprinus curfus, whether derived from a single 

 spore or from a large number of spores sown together, as discovered 

 by Miss Mounce ^ never produces any clamp-connections. 

 Brunswik,- using the fruiting criterion, as a result of a limited 

 number of matings of monosporous mycelia, found that C. curtus 

 is heterothallic, and this conclusion has been confirmed by a long 

 series of experiments carried out by Miss Dorothy Newton working 

 under my direction at Winnipeg. Miss Newton's criteria were the 

 production of oidia and the mode of branching after pairing mono- 

 sporous mycelia. In a series of experiments, confirmed by repeti- 

 tion, she found that the monosporous mycelia were of four kinds, 

 {AB), {ab), {Ab), and (aB), and hence concluded that individual 

 strains of C. curtus are quadrisexual. The paired mycelia were 



1 Irene Mounce, " Homothallism and the Production of Fruit-bodies by Mono- 

 sporous Mycelia in the Genus Coprinus," Trans. Brit. Myc. Soc, vol. vii, 1921, 

 pp. 210-211. 



- H. Brunswik, " Untersuchungen liber die Geschlechts- und Kernverhaltnisse 

 bei der Hymenomyzetengattung Coprinus.''' In K. Goebel's Botanische Abhand- 

 lungen, Jena, Heft V, 1924, p. 124. 



