OMPHALIA FLAVIDA 431 



wounds. The crystallising dish was then covered and set in diffuse 

 daylight on a table in the laboratory. The air within the dish very 

 soon became saturated with water vapour. 



Typical leaf-spots, which rapidly grew in size, were developed 

 within a week on both the wounded and the unwounded Bryo- 

 phyllum leaves and on the wounded, but not on the unwounded, 

 Oleander and Ficus leaves. About ten days after inoculation, a 

 crop of saffron-yellow gemmifers began to develop at the surface 

 of the infected areas (Fig. 217, cf. Fig. 201, p. 402) ; and, after 

 another ten days, at the edges of the same areas, a few typical 



Fig. 220. — Omphnlia flavida on an isolated leaf of Nerium 

 Oleander re.sting on wet sand in a Petri dish. The leaf 

 was dipped in • 1 per cent, corrosive sublimate, washed 

 in sterilised water, and placed on sterilised sand moistened 

 with sterilised water. The surface of the leaf was then 

 scratched with a needle and a piece of mycelium was laid 

 over the wound. After about a week, a few gemmifers 

 came up above the leaf. On the twenty-first day after 

 inoculation, the sporophores here shown began to make 

 their appearance. Photographed at Winnipeg twenty- 

 seven days after inoculation. Natural size. 



Omphalia flavida sporophores made their appearance (Figs. 218, 219, 

 and 220). Thus the mycelium, by producing both kinds of fruiting 

 structures, behaved in living leaves just as it had done in artificial 

 bread cultures. ^ 



In further experiments, Vanterpool and I succeeded in infecting 

 the leaves of Plumbago capensis ; but, in this species, the leaf- 

 spots developed gemmifers only, no sporophores ever making their 

 appearance. 



Omphalia flavida as a Non-specialised Parasite. — Many para- 

 sites, e.g. Uredineae, Ustilagineae, and most Peronosporeae and 

 Chytridiaceae, are highly specialised, some of them being restricted 



1 Cf. Figs. 203 and 204, pp. 404 and 405. 



