Erysiphe 233 



+ 



^ 



Professor Saccardo now agrees with the view that the position of 

 Phyllactinia on the Foincs is in all probabilit}^ an accidental one. 



Hitherto the presence of attached perithecia on a leaf has nat- 

 urally been considered as conclusiv^e proof that the funo-ys ori<T- 



inated there, but for the reasons mentioned above, such proof now 

 becomes invalid. . It is therefore very desirable that the reported 

 occurrences of P. corylca on herbs should be investigated in the 

 field, as it is impossible to prove from the examination of her- 

 barium specimens (unless perithecia can be observed springing 

 from a mycehum) if the fungus originated on the plant in question. 

 An observation of Fuckel's (133, p. 80) perhaps refers to tliis 

 reattachment of perithecia. This author remarks " dass die Peri- 

 thecien auf in der Nahe stehende Pflanzen, Avie Graser usw. ueber- 

 wucherten. Dasselbe mag wohl auch der Fall sein mit jenen, 

 welche Bagge auf Pcrtusayia fand." 



Professor Miyabe has sent me specimens (now in the Kew 

 Herbarium) of a very beautiful form of P. corylca from Japan, 

 growing on Paulozvnia impcrialis. The form is remarkable for its 

 large size. Many of the perithecia reach a diameter of 350/-^; 

 the appendages are more numerous than usual, being sometimes 

 as many as 25, when they are arranged so closely round the peri- 

 thecium that their bulbous bases touch one another. In these 

 perithecia the asci and spores show, likewise, a tendency to be 

 larger than usual. Intermixed with these large perithecia, how- 

 ever, are others which, in the smaller size of all their parts, agree 

 perfectly in ev^ery respect with ordinary P. corylca. Altogether, 

 we cannot consider that the Phyllactinia on Pai/hnvnia is anything 

 but a luxuriant form of P. corylca, which it would be inadvisable 

 to separate even as a variety. It is most probable that further 

 search on other Japanese plants would bring to light a complete 

 series of forms of Phyllactinia intermediate in size between this 

 large form on Paulownia and those of normal size. 



Since writing the above, I have noticed that Atkinson (9) has 

 described a form of Phyllactinia occurring on certain American 

 oaks {Qucrcus Phcllos, Q. nigra) as variety macrospora. The 

 form, from the description, is evidently comparable to the Japanese 

 plant mentioned above. The perithecia, apparently, are not so 

 large (200-250 }i in diameter), but the very large asci, reaching 



