II. On the structure and life-history of Entyloma Ranunculi (bonorden)

The author found plants ofRanunculus Ficaria , the leaves of which were all spotted with white patches; the white patches spread from leaf to leaf, and the disease assumed the nature of an epidemic The rise, progress, and climax .of the disease were observed both on isolated plants and m the open country, and the nature of the lesions in the leaves was made out. Evidence was found to support the view that some plants succumb more rapidly; this evidence was tested, and the circumstances to which the differences are due explained. The white disease-spots contain the extremely delicate mycelium ofEntyloma Ranunculi , and the. resting-spores of this fungus (one of the Ustilagineæ) were observed on it. The mycelium is intercellular, and makes its way in the middle lamella between contiguous cells. The white powder on the outside of the disease-spot consisted of conidia, very like those of some Ascomycetes. The author examined the anatomical connexion between the conidia and the resting-spores, and showed that the conidia really belong to the same mycelium —in other words, the conidia are a second kind of spore of theEntyloma .