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.On Entyloma ranunculi {Bonorden). [Nov. 25, 



II. " On the Structure and Life-History of Entyloma Ranunculi 

 (Bonorden)." By H. Marshall Ward, M.A., F.L.S., 

 Fellow of Christ's College, Cambridge, and Professor of 

 Botany in the Forestry School, Royal Indian Engineering 

 College, Cooper's Hill. Eeceived October 12. 



(Abstract.) 



The author found plants of Ranunculus 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 in 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 ex- 

 plained. 



The white disease-spots contain the extremely delicate mycelium 

 of Entyloma Ranunculi, and the resting-spores of this fungus (one 

 of the Ustilaginese) 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 the 

 Entyloma. 



Even more important is the germination of the conidia. This has 

 not been before observed in any Entyloma. The germination was 

 traced step by step, not only on glass slips, but also on the living plant. 

 These infections yielded the result that' the germinal hyphae entered 

 the stomata, and produced a mycelium exactly like that in the disease- 

 spots first investigated ; not only so,, but the resting-spores of the 

 Entyloma were produced on this mycelium, thus placing beyond doubt 

 the connexion of the two spores. It was observed that it required 

 a certain time for the disease to spread : this interval of time is the 

 same as that occupied in infecting plants with the conidia. Moreover, 

 all the symptoms of the disease produced by infection with the conidia 

 were as before. 



