50 



VINE DISEASE 



stage, differ in no respect from the byssoidal plant which infests the 

 Vine, Erysiphe^ for so the genus is now called, generally produces an 

 equal number of acrogenous and ovoidal seeds, as of brown, polysporous 

 conceptacula, precisely as is above described. Numerous investigations, 

 principally made on Kpannosa, Pr., E.Knautim, Dub., E, gxdtata, Wallr., 

 E. adunca, Grev., E. holosericea, Fr., E. Berheridis, DC, E. Prunastri, 

 DC, E, iampocarpa, Wallr., and E, Martii, Lev., have proved to me 

 that the fruits in question are very polymorphous in the same species 

 of Erydphe; that they may be either cylindrical or elongated, simple 

 or bilocular, naked or surmounted with a row of cells, ovoid, or glo- 

 bular, or perfectly spherical ; that some of the latter are destitute of a 

 filiform appendage, while others, furnished with the same distinguishing 

 hairs as the theca-bearing fruits, resemble the latter so closely as to be 

 indistinguishable by external characters. 



Many Mycologists stiU doubt whether those ovoid grains, which 

 cover with a white dust the filamentous thallus upon which the ascopho- 

 rous conceptacula of the Erysiphe are afterwards seen, can really ap- 

 pertain to these Eungi. They incline to the opinion that these grains, 

 and the white byssus which produces them, constitute together a pe- 

 culiar and perfect plant, a fertile O'idiitm, of which the Erysiphe would 

 be merely a parasite, or a more tardy accompaniment. This opinion is 

 bolstered up by the assertion, that Fungi possess only one kind of re- 

 productive organ ; but it is an opinion which is daily losing credit. 



Many cogent reasons militate against the ErysipJies being looked 

 upon as parasites, or merely as frequent accompaniments of the Oidmm. 



In the first place, the circumstance of their being constantly found 

 together, as the soi-disa^ii O'idium leucoconium, Desmaz., with the ErysipJie 

 pannosa, Fr., the 0. mQnilioides, Lk., and E. Graminis, DC, etc., is so 



unvaiymg 



Ery^ 



the latter would certainly be its parasite. It would also be our en- 

 deavour to distinguish, in the mycelium, which bears simultaneously the 

 stringed grains of the O'idium and the fruits of the Erysiphe, any fila- 

 ments peculiar to each ; for a minute scrutiny will prove that the con- 



Ery 



germinate into naked : 

 ;e, that there is no real 



in the case, nor two distinct and associated vegetables, but only one 



