Pethybridge & Laffkrty — -Disease of Tomato and other Plants. 499 



more or less decayed ; and microscopical examination revealed in them the 

 presence of phycomycetous mycelium bearing Phytophthora-like sporangia. 



The fungus was isolated and grown in pure culture. As far as the 

 morphological characters of its mycelium and sporangia are concerned no 

 differences could be seen between it and the fungus isolated from Tomato 

 plants. It was proved to be pathogenic to Aster, Tomato, Petunia, Wallflower, 

 and Gilia tricolor. 



The finding of this fungus in Aster recalled the disease of this plant 

 recently described by Eobinson (9) and attributed by him to a species of 

 Phytophthora. This author did not succeed in obtaining the sexual organs of 

 the fungus in pure culture, and hence did not identify it or name it. 



Mr. Eobinson was good enough to supply us with a culture of his fungus, 

 which, unfortunately, on its arrival was found to be contaminated with 

 bacteria. We succeeded, however, in getting it pure, and we carried out a 

 parallel series of cultures and infection experiments with it and with the' 

 strains isolated by us from Tomato, Petunia, and Aster. 



It was found that Eobinson's strain was pathogenic to exactly the same 

 plants as the others were, and produced the same type of disease. But whereas 

 in the case of the strains isolated by us from the Tomato and Petunia sexual 

 organs were produced in pure culture, this was not the case with the strain 

 isolated from Aster either by us or by Eobinson. 



A certain amount of doubt, therefore, must exist as to whether the fungus 

 causing the Aster disease is absolutely identical with P. cryplogea. Judging 

 from their very close similarity in other respects, however, and especially 

 seeing that the formation of sporangium within sporangium (hitherto 

 described for no other species) is common to both, it is clear that the two 

 fungi are very closely allied if not absolutely identical. It is possible, too, 

 that had the cultures been carried on for a more extended period, sexual 

 organs would have developed in the course of time. Unfortunately only 

 P. cryptogea from Tomato was carried over the period of eight months, during 

 which the work was suspended, in a living condition. 1 



Cheiranthus. — Diseased Wallflowers were observed alongside of the Asters 

 above referred to, showing similar symptoms. A similar fungus, bearing the 

 same kind of sporangia, was found in the affected tissues. The fungus was 

 not in this case isolated, but inoculation of healthy Wallflower plants with 



1 Mr. Brierley (Ann. App. Biology II, Mo. 4, Ap., 1916, p. 266) refers to tomato 

 plants as succumbing to " Black Neck {Phytophthora sp. omnivora 1) ." In correspondence 

 he informed us that he believed that this disease in tomatoes was identical with 

 Robinson's Black Neck of Asters, and was due to the same parasite. 



