536 RESEARCHES ON FUNGI 



This observation goes to show that the mode of spore-discharge in 

 Puccinia Malvacearum is exactly the same as in Puccinia graminis, 

 Endophyllum Euphorbiae-sylvaticae, and the Uredineae in general. 



The basidia which develop freely in air are curved like a sickle. 

 Evidence of this was obtained in various ways, among others by 

 isolating elements from a sorus of teleutospores upon a leaf which 

 had been kept for a night in damp air. The drawings in Fig. 215, 

 C, D, E, and F show such isolated elements ; and I, which is a 

 semi-diagrammatic drawing, shows a basidium with its four spores. 

 The curvature of the elements is in all cases obvious, and it is to be 

 noted that the sterigmata and spores are always developed on the 

 convex side of the basidium so that they are directed away from 

 the base of the teleutospore. 



An attempt to watch the development of the basidia was made 

 as follows. A vertical section through a piece of leaf including 

 about one-half of a sorus was placed in a closed compressor cell on 

 gelatine. Some of the teleutospores germinated (Fig. 215, A). At 

 their first origin they were straight (B), but they soon became 

 curved. Unfortunately the development of the basidia went no 

 further than is shown in Fig. 215, A ; but sufficient was seen to 

 indicate that the basidia are always curved and that the sterigmata 

 develop on the convex side. 



The relations of the basidia to the teleutospore-sorus and to 

 the leaf of the host-plant are shown in detail in Fig. 216, which 

 represents a sorus in which a number of teleutospores have just 

 germinated. Only some of the teleutospores germinate at any 

 one time. After some have germinated, others germinate. Perhaps 

 this is due to the fact that the teleutospores are not all developed 

 simultaneously. The older ones are pushed on long pedicels toward 

 the outside and younger ones are contained further within the 

 sorus. Germination takes place only in moist-weather periods, 

 especially after rains ; and, during continued dry weather, no germi- 

 nation takes place at all. This I was able to observe by making 

 daily observations on infected Hollyhocks growing in my father's 

 garden at Birmingham, England. In Fig. 216, a shows very young 

 basidia and 6 curved basidia with four full-grown spores. It will 

 be noticed that all the full-grown basidia are curved more or less 



