498 Scientific Proceedings, Royal Dublin Society. 



sufficient to state that the results showed conclusively that the two fungi 

 are not identical ; and we conclude that the tomato fungus is one which has 

 hitherto not been described. 1 



Its diagnostic characters may be summed up briefly as follows : — ■ 

 Phytophthora cryptogea sp. nov. Mycelio ramoso quoad partes recentiores 

 eseptato vetustiores septato ; conidiis plerumque inversipyriformibus 24-50ju 

 x 17-30^ apicibus obtusis non-papillatis sympodialiter genitis ; zoosporis 

 2-ciliatis 10-15/x diani. ; oogoniis hyalinis flaveseentibus pyriformibus 

 30/* diam. ; antheridiis amphigynis hyalinis; oosporis sphaericis flaveseentibus 

 crasso episporio praeditis 25^ diam. 



Hob. in radicis caulibusque vivis Lycopersici esculenti et Petuniae sp. in 

 Hibernia. 



VII. — The Disease in Plants other than the Tomato. 



Petunia. — Some time after beginning the study of the Tomato disease 

 we received specimens of Petunia seedlings suffering from a disease the 

 symptoms of which were very similar to those observed in the Tomato 

 plants. 



Microscopic examination of the diseased tissues confirmed this similarity, 

 for a Phytophthora-like fungus was present, bearing sporangia similar to those 

 observed in the case of the Tomato. 



The fungus was isolated from the Petunia in the same manner as was the 

 one from the Tomato, and it was grown in pure culture. It was proved by 

 infection experiments to be pathogenic not only to Petunia but also to 

 Tomato, Aster, Wallflower, and Gilia tricolor. 



In culture the fungus isolated from Petunia behaved exactly like that 

 obtained from Tomato, and, like the latter, it produced sexual organs. These 

 organs were similar in every respect in the two cases, and we conclude that 

 Phytophthora cryptogea is the cause of the disease not only of Tomato plants 

 but also of Petunias. 



Aster. — About the same time diseased Asters were observed in a garden 

 in the same locality as that from which the diseased Tomato plants were 

 originally obtained. The root systems and the lower parts of the stems were 



1 While the present paper was being prepared for press we found that Mr. G. T. 

 Spinks (14) had described a disease under the title "Damping-off and Collar Rot of 

 Tomatoes," which is probably identical with the one we have been dealing with. The 

 causative parasite appeared to be a species of Phytophthora, but it was not grown in 

 pure culture, and no sexual organs were obtained. It was not therefore identified or 

 described in detail. 



