WHITE MILDEWS OR BLIGHTS. 171 



those to wliicli we have 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, Elvrenhergii, Lev.)^ not yet 

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

 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 difi'ering 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 



