228 BOTANICAL GAZETTE [September 



also made in the same way on leaves placed in Petri dishes lined 

 with moist filter paper. In four days the radiating strands were 

 very evident with the aid of the low power of a microscope. Infec- 

 tion occurs by the entrance of the germ tube through the cuticle, 

 there being no stomata on the upper surface of the leaves. From 

 the subcuticular mycelium, hyphae later penetrate to the tissue 

 below, first filling the epidermal cells, and only in the advanced 

 stages of the disease penetrating the mesophyll. 



The way in which this fungus hibernates is no longer a matter 

 of conjecture. Scribner 21 suggested that the spores lodge on the 

 buds in autumn and remain there dormant until the leaves have 

 expanded the following summer. As has been found to be true 

 with many imperfect fungi, this fungus is carried through the 

 winter on fallen leaves and the ascosporic stage develops in the 

 following spring. 



This study shows that Gnomoniella rosae (Fkl.) Sacc. is 

 not the perfect stage of the rose Actinonema, as has recently 

 been suggested. 22 One species of Actinonema, however, has been 

 connected with an Asterella, Actinonema rubi (Fkl.) becoming 

 Asterella rubi (Fkl.) v. Hohnel. 23 He found in the spring the 

 Asterella stage on living canes of Rubus Idaeus. These areas had 

 been occupied the previous summer by the conidial stage. 



The genus Asterella was first proposed by Saccardo 24 as a 

 subgenus of Asterina for those species which have hyaline spores. 

 Later 25 he raised Asterella to generic rank. As Saccardo himself 

 points out, further investigation of species which are at present 

 placed in the genus Asterella will result in their transfer to Asterina, 

 since the spores become brown at maturity. Lindau 26 thinks the 

 existence of this genus is still questionable. Subsequently but 

 little investigation has been made on the genus and no clear-cut 



21 See footnote 7. 



"Laubert, R., and Schwartz, Martin, Rosenkrankheiten und Rosenfeinde. 

 16-19. 1910. 



2 * Von Hohnel, F., Uber Actinonema rubi Fuckel ist Asterella rubi (Fkl.) v. 

 Hohnel. Ann. Myc. 3:326. 1905. 



*4 Saccardo, P. A., Syll. Fung. 9:393. 1891. 



25 , Syll. Fung. 1 : 25 and 42. 1882. 



26 Lindau, G., Engler and Prantl's Pflanzfam. 1:340. 1897. 



