160 DISEASES OF FIELD & GARDEN CROPS. [CH. 



patches, on the leaves. If we examine the upper surface 

 of the leaves we shall see reddish patches similar with 

 those below, but these upper patches are more or less 

 covered with little black dots technically termed spermo- 

 gones. These spermogones, of which there are four groups 

 in Fig. 82, are illustrated at BBB. Although the spermo- 

 gones usually grow on the upper surface of the leaf, 

 sometimes they may be seen on the lower surface. They 



Fig. 82. 



Barberry leaves invaded by JEcvlium Berberidis, Pers. 

 Natural size. 



sometimes grow on the same patches with the 

 cups on the lower surface ; at other times they appear by 

 themselves without ^Ecidia. As each spermogone dot is 

 smaller than the point of a pin they are easily overlooked, 

 especially when they grow in very small companies, or as 

 single specimens. The spermogones usually appear before 

 the dEcidium cups. 



If we look at the black dots with a strong lens we shall 

 still, owing to their excessive smallness, only see them as 



