146 THE GRAPE. 



similiar in structure, if not positively of the same genus — 

 are most prevalent when a slow steady under current cf 

 dry air is passing in hot weather, which, by exciting t<^ 

 an extraordinary degree of evaporation, leaves a damp 

 clamminess upon the surface of all plants by drawing out a 

 portion of their collected juices, which then becomes food 

 for the sporules to vegetate upon. This may be considered 

 somewhat similar to the bottom draft in a hot-house — a 

 very different thing, by the way, to a healthy and free 

 ventilation overhead, where the air is made to circulate 

 evenly over the whole cubic bulk, without that continual 

 stream from small apertures below. In our present case, 

 moisture combined with heat will counteract the fungus, 

 and it may be effectually got rid of by syringing with 

 water, in which a portion of sulphur is mixed; one pound 

 of the latter will be enough for ten or fifteen gallons of the 

 former. If the fruit be approaching to maturity, this kind 

 of application will disfigure it, and the same purpose may 

 be as effectually gained by dusting a small quantity on 

 the heating apparatus where it will not ignite ; or if a cold 

 house, by strewing it over the floor in the same quantity 

 as before advised. 



The peculiar circumstances under which parasitical 

 fungoids luxuriate, are wonderfully dependent on the state 

 of the atmosphere. This is demonstrated, not only by the 

 different sorts of grape mildew, but in all others. 



All plants indeed are not alike susceptible to these 

 influences. The constitution of various plants may be able 

 to withstand the effects of atmospheric changes without 

 revulsion or excessive flow of the sap, and therefore they 

 will not afford those precise requirements which favor the 

 germination of the fungi. But as a general rule like causes 

 produce like effects. 



It follows, then, if the above observations are correct, 



