CULTURE OF THE GRAPE. 229 



vious evil. But it is clear that this is not the case. This 

 viscid appearance is sometimes noticed upon the leaves; 

 but, under favoring weather, the mildew is not developed, 

 and the vines do not suffer materially. On the other 

 hand, the strictly parasitic growth of the mildew notice- 

 ably and speedily sucks out the life of the leaf. Again : 

 when we apply dry suphur as a remedy, manifestly it is 

 not to take off the viscid matter, but simply to destroy 

 the life of the parasite. When this last result is accom- 

 plished, the vine recovers its health, though the viscid 

 matter remains. 



All our views and theories in regard to mildew must 

 bend to facts. It is of the utmost importance that we have 

 the experience and observations of scientific men, in order 

 that, by a comparison of cases under a variety of circum- 

 stances, we may be able to build a true philosophy of the 

 evil. With the hope of contributing to this end, I make 

 free quotations. In " The Horticulturist," vol. xviii. p. 304, 

 Prof. B. Silliman, jun., mentions the case of a Catawba 

 vine twenty years old, covering an open space in front of 

 his piazza, twenty-one feet long and twelve feet high, 

 above which is a cornice projecting rather over a foot 

 beyond the wires on which the vine is trained. "The 

 exposure is west by north ; and, although it is Inte in the 



