THE FUNGI WHICH CAUSE PLANT DISEASE 273 



were usually entirely embedded, with the beaks only protruding 

 and were often numerous and crowded. Cultural evidence that 

 Edgerton's specimens were actually genetically connected with 

 the cotton anthracnose are wanting. 



The fungus has been repeatedly studied in pure culture and 

 numerous inoculations have thoroughly proved its pathogenicity, 

 the disease usually showing within 

 a few days after inoculation, though 

 sometimes incubation is delayed 

 much longer. 



Infection of stems is often at a 

 wound such as a leaf scar; or on 

 leaves at some point of weakness. 

 Cotyledons and yoimg plants are 

 especially susceptible. On bolls 

 infection is conmion at the line Fig. 202.— G. gossypU, D, and E, fun- 

 of dehiscence of the carpels. Ac- ^Jlefw! '" °°**°° "°* ^^""' 

 cording to Barre, there is evidence 



that the fungus may destroy the contents of the boll before 

 it shows upon the outside. Barre showed that 44% of flowers 

 that received spores within ten hours after opening produced dis- 

 eased bolls; but inoculations by spraying produced no results on 

 bolls after they were three-fourths grown. 



Seed from a field that bore 35% infected bolls gave on germina- 

 tion, 12% of infected seedlings, the disease appearing upon cotyle- 

 dons or hypocotyls even before they unfolded. Atkinson"" found 

 that conidia five months old were alive, but that at seven months 

 they failed to germinate. Barre also found the conidia and the 

 mycelium of the fungus to be comparatively short lived. 



G. atrocaipi Del. on Atrocarpus leaves has been described as 

 a perfect stage of Glceosporium atrocarpi Del. 



A fungus on Cattleya "^' "^ described by Maublanc & Lasnier 

 as a Physalospora should perhaps be considered as a Glomerella. 



Gnomoniella Saccardo (p. 263) 



Perithecia sunken and usually remaining so, with a long cylin- 

 dric, erumpent ostiole, leathery, black; asci ellipsoid or fusoid, 



