330 W. B. GROVE. 



(Ecidium. The epidermis of the leaf remains uninjured, as 

 also the fibro- vascular bundles which traverse the aflPected 

 part. 



The elevated and convex surface of the stroma, usually on 

 the under side of the leaf, is covered towards the end of June 

 with numerous minute scarcely perceptible darker dots, 

 which are the openings or ostiola of the spermogones. These 

 spermogones originate within the stroma in dense coils of 

 interwoven hyphoe, which at length form a hollow ball of deep- 

 red pseudo-parenchymatous tissue, '1 mm. in diameter, which 

 penetrates the epidermis by its obtusely conical apex, ter- 

 minating in a pore, while the inner surface of its wall is clothed 

 with a dense layer of linear, straight, simple basidia, from 

 which the spermatia are abstricted. The latter are very 

 slender, filiform, attenuated and uncinate above, about 30 mk. 

 long ; as they accumulate, they are forced out of the ostiolum, 

 and being involved, as is usual in such cases, in a gelatinous 

 mucus, are heaped in a globule round the apex. These sper- 

 matia continue to be developed until the middle of October. 



So much was known, in the main, to Tulasne ; he was also 

 acquainted with the subsequent development of perithecia and 

 the ripening of the ascospores in the succeeding spring. But 

 he believed that the perithecia did not appear upon the living 

 leaves, being developed only after they had fallen from the 

 tree and lay rotting on the ground ; in fact, that the spermo- 

 gones had ceased to be developed before the formation of the 

 perithecia began, and therefore the connection between the 

 two, if any were suspected to exist, could only be indefinitely 

 imagined. It is here that the recent discoveries of Frank and 

 risch throw a new light and add another to the cases already 

 known where a true sexual act exists among the Ascomycetes. 

 The investigations of these two authors mutually supplement 

 and confirm each other, and, as they were independently made, 

 give strong reasons for believing in the truth of their con- 

 clusions. 



The foundations of the future perithecia are laid in the 

 stroma of the fungus, while the leaves are still living and 



