464 BOTANICAL GAZETTE [DECEMBER 
passed over, as the methods used by them were not sufficiently deli 
cate to enable them to determine the exact method of ascus formation. 
The end cells of ascogenous hyphae described by DEBary for Euro- 
tium, for example, may as well represent subterminal cells. In the 
mildew, Erysiphe communis (HARPER ’96), the end cells of the asco- 
genous hyphae may develop the asci. This is also the case in Phyl- 
lactinia corylea (HARPER :05), but asci may also be formed as lateral 
branches of intercalary cells. In Sphaerotheca castagnei (HARPER 
’95) and S. humuli (BLACKMAN and FRASER :05) the oogonium 
develops into an ascogonium of five or six cells, of which the penulti- 
mate one grows into a single ascus. In this genus there are no asco- 
genous hyphae, unless we accept the interpretation of BLACKMAN and 
FRASER that the ascogonium is a single ascogenous hypha, whose 
penultimate cell develops an ascus in the manner described by DAN- 
GEARD. In Anixia spadicea (FAULL :05) the asci spring from any 
cell of the ascogenous hyphal system. 
In the Tuberaceae, 7’. melanos permum (DANGEARD ’94, GUILLIER- 
MOND :04) has its asci arising as described by DANGEARD; while 
Genea hispidula (FAULL :05) shows a marked variation from this 
type. In this form the ascus grows out from a curved terminal cell. 
FAULL suggests that perhaps the only difference between this and 
the other type is the lack of a cross wall cutting off the uninucleate 
hyphal tip. 
Among the apogamous Pyrenomycetes, such as Teichospora 
trimor pha, T. aspera, T. nitida, and Teichos porella sp. (Miss NICHOLS 
’96), a uninucleate ascus arises from a single central cell of the peri- 
thecial mass. Hypomyces Thiryanus (MaAIRE :05) follows the 
method described by DANGEARD; while in Podospora ascerina, P. 
setosa, Sordaria fimicola, and S. humana (FAuLL :05) the asci arise 
from a curved terminal cell of an ascogenous hypha. In Phyllachora 
graminis (FAULL :05) the ascus arises from a curved cell of the tip 
without the formation of a uninucleate tip-cell. 
The Discomycetes are described as showing the greatest uniformity 
in the method of ascus formation, which may perhaps be due to the 
fact that more careful work has been done upon them. All the 
following forms have their asci formed in the manner described by 
DANGEARD (’94) for Peziza vesiculosa: Borrera ciliaris, Acetabula 
