CH. m.] PERONOSPOKA EXIGUA. 13 



single spore, or conidium, is enlarged 1000 diameters at 

 B. The parasite causes putrescence, and grows within 

 the leaf and in effused patches on the surface, as does 

 P. trifoliorum, D.By. The illustration shows a some- 

 what large group of fruiting fungus threads, growing 

 upon a fragment of a leaf hair of Lotus corniculatus, L. ; 

 the mycelium has caused a gouty discoloured swelling to 

 appear on the hair. The spore - supporting threads are 

 frequently simple, or sometimes once, twice, or three times 

 branched and furnished with a few joints, stops, or septa ; 

 the spores are borne on minute, often lateral spicules ; 

 and as the branches grow, the spores have a tendency to 

 drop off, as in the Peronospora of the potato disease. The 

 spores are slightly oval, almost round, and burst at the 

 side on germination. P. exigua, W.Sm., sometimes grows 

 on clovers in company with P. trifoliorum } D.By., but 

 it is immediately distinguished by its very much smaller 

 size, as well as by its specific characters. Though com- 

 mon, this species has hitherto been overlooked, probably 

 because its appearance on clover leaves to the unaided eye 

 is precisely the same with that of P. trifoliorum, D.By. 



PERONOSPORA EXIGUA, W.Sm. Minute, conidiophores 

 simple or slightly branched, slender, sparingly septate, 

 conidia oval, almost globose, very small, very pale gray, 

 sometimes borne on one side of the conidiophore only, 

 non-papillate, bursting at the side on germination. On 

 Leguminosce, often in company with P. trifoliorum, 

 D.By. 



The " New Clover Disease," described by P. Mouille- 

 fert in the Journal d' Agriculture Pratique, 1874, pp. 667, 

 670, and translated by Mr. William Carruthers, F.K.S., 

 in the Journal of the Royal Agricultural Society of England, 

 Vol. x., Part ii., 1874, is possibly one form of clover 

 mildew, caused either by Peronospora trifoliorum, D.By., 

 or P. exigua, W.Sm. In the disease described by P. 

 Mouillefert the fungus appears to be chiefly confined to 

 the base of the stems of clover. The author says he has 



