554 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



"Apres I'expulsion des spores et la chute des soies, le perithece. 

 (rappelant par sa consistance et son aspect le Sclerotium durum) 

 persiste sur les tiges dessechees du Solauum tuberosum.'' 



" Plomereuc (Seine-Inferieure, Mars 1884)." 

 "Abbe Letendre." 



From our own studies and as already stated, what is taken 

 for pycnidia are only sterile sclerotia, since studies made of these 

 pycnidia at different stages of development in pure culture and 

 on the host proved them to be sterile bodies. The fungus therefore 

 is perhaps an intermediate form between Vermicularia and Col- 

 letotrichum, although it fits in better in the latter. There are no 

 described species of Colletotrichum which are known to produce 

 sclerotia. However, there seems no doubt but that many of the 

 species of Vermicularia, upon culturing, would show characteristics 

 of the former genus. 



It seems evident that Phellomyces sclerotiophorus Frank is the 

 same as Vermicularia atramentaria Berk. & Br. and also the same 

 as Colletotrichum solanicolum O'Gara. However, in following 

 the rule of priority, the fungus becomes Colletotrichum atra- 

 mentarium (Berk. & Br.) Taubenhaus. Syn. Vermicularia atra- 

 mentaria Berk. & Br., 1850; Phellomyces sclerotiophorus Frank, 

 1897; Colletotrichum solanicolum O'Gara, 1915. The fungus needs 

 no further description, as it has been fully described by O'Gara. 

 However, it should be added that the spore measurements as 

 given by him (3.5-5 m X 17 /x) are found to be much more variable 

 in length (figs. 24 and 25). 



The fungus Colletotrichum atramentaritim docs in no way re- 

 semble Periola tomentosa Fr. occurring on dead potato vines in 

 Europe. Further studies of this genus will show that it is probably 

 invalid. 



Pathogenicity. — It has already been pointed out that in 

 culturing silver scurf spots, the great majority of the plates 

 yielded the fungus Colletotrichum atramentarium (fig. 3). One 

 would therefore be tempted to suppose that the latter fungus was 

 the cause of silver scurf. Moreover, no previous workers reported 

 infection with spores of pure cultures of Spondylocladium atro- 

 virens. Appel and Laubert (11) in their infection experiments 

 merely used spores of this organism obtained from infected tubers 

 which were kept in a moist chamber. These spores were diiuted 



