438 BOTANICAL GAZETTE [DECEMBER 
sipheae. This secondary parasite proved also not uncommon when 
sought for; but seldom fruited unless somewhat protected as above 
described. In one instance it was found spreading copiously from - 
a twig affected by the Taphrina to the healthy foliage of the host; 
but in all other cases observed it was practically confined to leaves 
already affected by the other parasite. The perithecia being 
small and inconspicuous when scattered on the healthy leaves, it 
is not impossible that I may have overlooked it, and that it may 
naturally grow apart from the Taphrina. The reaction between 
the two, however, was very evident, the growth upon leaves invaded 
by the Taphrina being very much more luxuriant and the perithecia 
much more abundant. A similar phenomenon is seen in the case 
of the Microsphaera on Berberis referred to below, and may be 
comparable in a way to that seen in the Erysipheae inhabiting 
the hexenbesen of Phytoptus on Celtis, or the erinoses of Fagus 
and Cephalanthus. When examined microscopically, this fungus 
proved to be an Uncinula almost as peculiar as the Taphrina with 
which it was associated, owing to the very unusual modification of 
its appendages, which become distally twisted in a close spiral 
of striking appearance. The perithecia (fig. 7), which are usually 
epiphyllous, although sometimes amphigenous, are often densely 
crowded, of a reddish-brown color, globose-depressed, coarsely 
areolate. They show considerable variation in size (70-100 #), 
and in the number of asci (5-8) contained in each. The appendages 
(figs. 7, 8) are 4-8 in number, without septa, the basal portion 
thick-walled and suffused with reddish brown, the suffusion involv- 
ing also one or sometimes more than one turn of the spiral portion, 
which is otherwise quite hyaline and may show as many as eight 
turns, sometimes but half this number, ending in a helicoid extrem- 
ity (figs. 8, 9), of characteristic contour, thin-walled, and somewhat 
inflated. The appendages are quite rigid, and curve somewhat 
upward from their insertion on the equatorial region, whence it is 
evident that the twisting does not assist in freeing them from the 
substratum, but, if it has any significance, must be supposed to 
enable them to become more readily attached to objects with which 
they may come in contact. A somewhat similar phenomenon is 
seen in Sphaerotheca spiralis Neger, discovered by DusEN on Escal- 
