PROCEEDINGS OF THE FARMERS' CLUB. 113 



transverse partitions. The lowest of these taper into a filiform 

 stalk, while the upper ones are gradually thickening towards the 

 top, where they become egg-shaped, and consist of spore cases, 

 which are filled with a great number of extremely small ovate 

 white spores or seeds, swimming as it were, in a limpid, gelati- 

 nous juice. 



The cells of the parasite and its sporidia are perfectly trans- 

 parent in their middle, but opaque at the margins. At first, the 

 extreme cell only becomes ovoid, but in the progress of growth 

 those beneath it acquire the same form, and then the entire fun- 

 gus represents a necklace or chain. Very often, too, and par- 

 ticularly on the pedicels, and at the base of the berries (where 

 the fungi grow more gregariously), additional sporidia spring in 

 the shape of clusters from the site of the intermediate and ter- 

 minal cells. 



At the slightest touch or commotion the sporidia separate 

 from the filaments either singly or in heaps of three or four, and 

 are carried by the winds to plants hitherto uninfected, or scat- 

 tered upon the cuticle below, where they commence germinating, 

 by throwing off from one or both extremities, slender creeping 

 threads, which in their turn become the spawn of fresh para- 

 sites. 



All portions of the epidermis attacked by the oidium lose their 

 natural aspect; they get discolored, and through the destruc- 

 tion of the superficial cells or the parenthyma small lurid specks 

 are produced, Avhich become confluent, and cover part of the 

 cuticle with yellowish-brown irregular spots. 



To account for the proximate cause of the malady is as yet 

 difficult, it having made its appearance in a few localities and on 

 some particular kinds of the grape only, though all of them have 

 been exposed to the same meteorological condition. It may be 

 that some varieties are more susceptible than others for the 

 infection, but while this must remain hypothetical for a while, 

 no precautions should be omitted, and no means left untried in 

 order to arrest the progress of the plague. 



Powdered sulphur, and strong decoctions of tobacco leaves 

 have been recommended by various authors, but the application 

 of the former on an extensive scale seems impracticable, while 

 the latter, a vegetable substance, may be liable to fungoid 

 destruction itself. It strikes me, however, that a weak solution 

 of chloride of lime may be of use, and could easily bo experi- 



[Am. Inst.] H 



