34 MICROBES, FERMENTS, AND MOULDS. 
forms floury patches which send forth a peculiar 
musty smell. 
The oidium may remain latent on the vine-stock 
throughout the winter. In the spring it reappears 
in yellowish patches on the earliest leaves, on which 
it is rapidly propagated; the plant languishes, and 
the leaves become palevand, as it were, anzemic. 
Very dry weather is unfavourable to oidium, and 
so also are heavy rains, which wash the fruit and 
leaves, and carry away the spores on to the soil. 
The remedy consists in the application of sulphur 
to the infected vines. Flowers of sulphur is used, 
which acts upon the fungus by gradually setting free 
sulphurous acid. Under this influence the microscope 
shows that the superficial mycelium and the fragile 
spores dry up as if they were burnt (Ed. André). 
Three successive applications are necessary, and these 
are made with the help of a special instrument in 
the form of a pair of bellows, to which a rose is 
affixed, in order to disseminate the flowers of sulphur. 
The first application is made in spring, when the 
shoots are from eight to ten centimetres long; the 
second directly after the vine has blossomed; and 
the third when the grapes begin to ripen. The opera- 
tion in spring is the most important, and should be 
performed with the utmost care, so as to affect all 
the hybernating spores from which the succeeding 
generations would issue. Not only the upper and 
lower sides of the leaves must be dusted, but also 
