ENDOPHYLLUM EUPHORBIAE-SYLVATICAE 513 



Then it is safe to assume that the four basidiospores lying around 

 one of these isolated aecidiospores have been discharged from its 

 basidium. With the help of a micrometer the distances of the 

 spores from their basidium can be at once measured. A number 

 of such measurements were made, and it was found that the basidio- 

 spores had often travelled a horizontal distance of 0-2-0-3 mm. 

 before settling. The maximum distances observed were rather 

 less than 0-5 mm. This distance agrees in its order with that 

 observed by Coons and Dietel for other Uredineae. Coons, it will be 

 remembered, observed that the basidiospores of Gymnosjjorangium 

 Juniperi-virginianae can be shot away 0-26-0 -36 mm., while Dietel 

 came to the conclusion that in several species of Puccinia, etc., the 

 spores can be shot 0-6 mm. in a horizontal direction and 0-3 mm. 

 upwards, and that in Coleosporium, which has large spores, the 

 maximum horizontal distance may be as much as 0-85 mm. 



A comparison of the observations made upon Endophyllum 

 Euphorbiae-sylvaticae with those made ujDon Puccinia graminis and 

 those to be described for P. Malvacearum has convinced me that 

 there is nothing primitive about the structure of the basidium in 

 Endophyllum or in the mode of spore-discharge. My investigations 

 therefore support Dietel's view that Endophyllum has obtained 

 its peculiar life-history by reduction rather than the view of 

 Grove that this fungus is a primitive member of the Uredineae 

 which has never developed typical teleutospores. I shall show, in 

 connection with Puccinia Malvacearum, that the sickle shape of the 

 basidium and the arrangement of the spores on the convex side, 

 which characterise the basidia of Uredineae in general, are of high 

 importance in permitting of the efficient discharge of the basidio- 

 spores from teleutospore-sori developed on stems and leaves, etc. 

 The use of the curvature in the basidium is by no means so obvious 

 when the basidium is developed from isolated aecidiospores, as is 

 the case in Endophyllum. Yet the basidia in Endophyllum are 

 frequently curved in the typical manner (Fig. 206, B, E), with the 

 basidiospores arising on the convex side. I am inclined to think 

 that this tendency to marked curvature in the basidium of Endo- 

 phyllum has been inherited from Uredineae in which it was an 

 important factor in securing the liberation of the basidiospores, i.e. 



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