THE FUNGUS CAUSING BLAST AND SCALD. 15 



exposed. In most cases they are thickly and evenly distributed over 

 the sui'face of the leaf, except for the infrequent occasions when only 

 a portion of the leaf has been killed by the fungus (PL II, figs. 1 and 

 2). Mature pycnidia contain great numbers of pycnospores, bearing 

 at their apexes a rather inconspicuous appendage consisting of 

 granular matter, which appears to be embedded in a somewhat gelat- 

 inous substance. They are borne on short, simple sporophores 10-15 ^ 

 long. These pycnospores are hyaline, obovoid, with the apex fre- 

 quently truncate, and measure from 10.5 to 13.5 by 5 to 6 ^. The 

 appendage is usually about the length of the spore, or somewhat less, 

 and curved (PL II, fig. 3, , 6, c). At maturity these pycnospores 

 are expelled from the pycnidium in a small gelatinous tendril or 

 threadlike mass, being held together by the gelatinous substance of 

 the spore appendages as Avell as the free gelatinous matter which 

 appears to be produced within the pycnidium and forms a thin layer 

 about the pycnospore. 



Ascogenovs form. The ascogenous perithecia are much less fre- 

 quently found than the pycnidia. The perithecia resemble the pyc- 

 nidia very closely in form, size, and other characteristics (PL II, 

 fig. 10). In fact it is almost or quite impossible to determine, in the 

 absence of asci or pycnospores, to which form a particular fruiting 

 body may belong. The perithecia seem to have a denser, somewhat 

 more opaque w r all than the pycnidia, and they contain oblong, or 

 somewhat clavate, short-stipitate, or sessile asci, the spore-bearing 

 portion varying from 52 to 60 by 9 to 12 ^ the total length being GO 

 to 80 fji (PL II, fig. 11). The asci contain eight hyaline, or, when 

 old, slightly yellowish brown, short elliptical or subrhomboid asco- 

 spores, having the contents rather coarsely granular (PL II, fig. 12). 

 They vary in size from 13 to 16.5 by 6 to T/x. No paraphyses have 

 been found. The characters of the ascogenous form of this fungus 

 seem to agree most nearly with those of the genus Guignardia and 

 correspond very closely to the black-rot fungus of the grape (Guig- 

 nardia ImJwellii (Ell.) V. & R.). The pycnidial stage of Guignardia 

 bidwellii, as described and illustrated by Viala 18 and others, differs 

 from the pycnidial stage of the cranberry scald fungus in scarcely 

 any particular except in the absence of the spore appendage. A 

 recent careful study of fresh pycnidia of (Guignardia bidweUii shows 

 that its pycnospores also bear a similar appendage. It is, however, 

 shorter and less easily distinguished than that of Guignardia raccinii, 

 and soon disappears in mounted specimens. The appendage in the 

 case of the cranberry fungus is very constant and characteristic. 



The cranberry scald fungus is rather generally distributed through- 

 out the cranberry-growing sections of this country. Pycnidia have 

 been found on either leaves, flowers, or fruit in West Virginia, New 

 no 



