XX.] 



GRASS MILDEW. 



129 



but when magnified with a moderately high power of the 

 microscope, they appear as spherical bodies, furnished with 

 a large number of slender, curved, radiating, tentacle-like 

 arms or branches, the whole growth being partly buried 

 in the spawn, as illustrated in Fig. 57, enlarged 100 

 diameters. The limit of the page will not admit of a 

 higher magnification than 100 diameters; it must there- 



Fig. 57. 



Conceptacle of ErysipJie graminis, D.C. 

 Enlarged 100 diameters. 



fore be borne in mind that this Erysiphe is a comparatively 

 large fungus when placed side by side with others which 

 are magnified 200 and 400 diameters. The difference 

 in size between this Erysiphe and Peronospora exigua, 

 W.Sm., illustrated, enlarged 400 diameters, in Fig. 2, is 

 very striking. 



