WHITE MILDEWS OR BLIGHTS. 171 



those to wliich we liave referred ; indeed^ this genus 

 (or sub-genus) has the most elaborate and beautiful 

 forms in these appendages of any of the Erysiphei. 

 A figure is given of the tip of a fulcrum from a 

 continental species (M. Wirenhergii, Lev.), not yet 

 found in this country (fig. 233). In the berbeny 

 blight the appendages are straight at the base, 

 but afterwards become forked, each fork being 

 again forked, and these yet again branched in a 

 similar manner (fig. 230) ; so that a complex dicho- 

 tomous tip is formed to each of the appendages 

 (fig. 231). Each conceptacle contains about six 

 sporangia, and each sporangium contains from six 

 to eight spores (fig. 232). 



The common gooseberry is also liable to a visita- 

 tion from an allied species, in many respects closely 

 similar, but differing in - having the tips of the 

 appendages more branched, and the extremities of 

 the ultimate branchlets are not entire and at- 

 tenuated, as in the berberry mildew; but divided into 

 two toothlike processes. The conceptacles in this 

 species contain from four to eight sporangia, each 

 of which has four or five spores. 



In England, the leaves of the guelder-rose, and 

 in France (perhaps also in this country) those of 

 the alder, nourish a parasite belonging to this divi- 

 sion. This " blight '' possesses so much in common 

 with others to which allusion has been made, that 

 it will scarcely be necessary to describe it in detail. 

 A figure of the tip of one of the appendages of the 



