CULTURE OF THE GRAPE. 221 



and, shrivelling with the berry, eject a more or less curled 

 or twisted thread, which, moistened, becomes gelatinous, 

 and shows the innumerable oval sporules (0.004-0.005 

 line long), each embedded in its coat of mucilage." 



The first species of fungus, which Dr. Engleman calls 

 Botrytis, is very similar to, if not identical with, the Euro- 

 pean Oidium Tuckeri. Another species (Erysiphe) is more 

 frequently seen upon the European varieties of grapes, 

 though it is sometimes found upon our native kinds, indi- 

 cating that it may at a future day become a source of 

 evil. It is entirely distinct, developing upon the upper 

 surface of the leaf in the form of a white powder, which 

 spreads like a web, enveloping leaf and fruit. This may 

 be peeled off with ease, leaving the foliage uninjured, as 

 the roots of the fungus do not appear to penetrate the 

 leaf to any extent. Hence it may not be called a para- 

 site, but rather an epiphyte, in its habit of growth. But 

 it is a serious check to the vine, and will entirely prevent 

 the ripening of the fruit. This last species is of rare 

 occurrence upon our native grapes, but may be observed 

 upon the European varieties of gooseberry. 



I believe it is well ascertained that all those species of 

 parasitic fungus which infest the grape, and which we 

 call mildew, vegetate most rapidly in a moist atmosphere. 



