DEFENCE. 95 



tions have been weakened, by their being placed 

 outside the vulgar struggle for existence which is 

 incessantly continued in Nature, often suffer from the 

 attacks of an extraordinary number of these fungi. As 

 the Vine has been perhaps better studied than almost 

 any other plant, it may be interesting to give a list of 

 its special fungus enemies ; most of them are not found 

 on any other species. 



(i) The root is attacked by a fungus, Pourridie or 

 Weinstockfaule {Dematophora necatrix). The absorbing 

 threads or " mycelium " grow through the soil to 

 attack the roots of neighbouring plants ; they destroy 

 the soft tissues, and especially the fibrous rootlets. 



(2) Upon the leaves any of the following fungi may 

 be discovered: The "downy" or "false mildew" 

 {Plasjnopara viticold), which belongs to the potato- 

 disease group, and produces whitish patches on the 

 underside of the leaf; Uredo vitis forming spots on 

 the upper surface, and belonging to the Rust-fungi ; 

 Colletotrichum anipelinnvi forming small dry spots on 

 the leaf surface, sometimes shrivelling up the whole 

 leaf; Cercospora viticola also a leaf- spot form; 

 the " Brunissure " {^Plasinodiophora vitis)^ one of the 

 slime fungi (see below), which lives inside the soft 

 tissue of the leaf, forming light brown star-shaped 

 spots, and causing a premature leaf-shed ; Sphaerella 

 viiis chiefly on withering leaves. 



(3) The following occur on the young shoots, and 

 sometimes on the leaves and fruit : " Black-rot " 

 Laestadia Bidzvellii^ Gloeosporium ainpelophaguin (also 

 called " Bhck-rot " and not certainly distinct from 

 the preceding), and the " WMte-rot " {Coftiothyruwt 

 diplodielld). 



(4) The green bark is subject to the dreaded 



