172 MICEOSCOPIC FITNGI. 



in patcheSj has often a pinkish, or violaceous tint, 

 and glistens like hoar-frost. This affection of the 

 leaves was, at one timej believed to be produced by 

 a fungus which was called Erineum acerinum, but 

 now it is regarded as a diseased state of the tissues. 

 In the maple mildew, both surfaces of the leaves 

 are alike affected, and the little, dark, point-like 

 conceptacles will be found studded over both. It 

 is not uncommon to meet with very white leaves, 

 caused by the myceUum, but which bear no fruit. 

 The appendages iu this species are shorter than in 

 the last (fig. 225), and the tips are bifid (fig. 226), 

 or divided into two short branches, each of which 

 is bifid, and uncinate or hook-shaped (fig. 227). The 

 conceptacles contain not less than eight sporangia, 

 each of which encloses eight spores. 



Amongst the parasites that prey upon the much 

 abused berberry (which has been charged in turn 

 with producing the mildew in corn), is one which 

 causes the green leaves to assume a chalky appear- 

 ance (fig. 229), though less conspicuously than in 

 the maple blight. This parasite is the berberry 

 mildew {Microsphceria berberidis, Lev.). In such 

 localities as the writer has met with the berberry 

 suffering from mildew, he has invariably found a 

 larger proportion of leaves with the barren myce- 

 lium, than of those on which the conceptacles were 

 developed. Perhaps in other localties this may not 

 be the case. The appendages, as wiU be seen on 

 reference to our plate, differ materially from any of 



