Mar. 8,1924 
Nocturnal Production of Sclerospora 
781 
on Pennisetum typhoideum Rich, and Andropogon sorghum (L.) Brot. is 
apparently the same on both hosts, the conidial stage found on the latter 
host differed markedly from the typical conidial S. graminicola which 
developed on Pennisetum. Conidia produced on A. sorghum , by their 
distinctly subspherical shape, absolute lack of an apical papilla of de¬ 
hiscence, and invariable germination by tubes, consistently present, 
even though agreeing in size, a very decided contrast to the broadly 
elliptic, apically papillate, zoospore-forming conidia of the type. More¬ 
over, the branch system of the Andropogon fungus was more extensive 
than that of the type, and the sterigmata reached a length of 16.3/1 
while those of the type were but 8.3/x. Also, the fungi showed differences 
in their effect on the two hosts in the field and in their failure to produce 
cross infection. As a result, Kulkami establishes the fungus on A . 
sorghum as 5 . graminicola var. Andropogonis sorghi. 
In the opinion of the writer, this is certainly a distinct species, one 
which, aside from other differences, needs only the absolute criterion that 
its conidia lack an apical papilla of dehiscence to distinguish it without 
question from S. graminicola . It is clearly a species closely allied to the 
destructive, predominantly conidial Sclerosporas of the Orient even 
though it is apparently connected with an oogonial stage, presumably 
that of 5 . graminicola . Also, it promises most interesting results if 
studied intensively through numerous cross inoculations, comparative 
measurements of large numbers of conidia, and persistent efforts to 
determine whether it is or is not actually genetically connected with the 
typical S. graminicola oogonia on various hosts. Even before such an 
investigation is made, however, we are, in the writer's opinion, justified 
in regarding the apical papilla of dehiscence of the conidia of S. gramini¬ 
cola as a diagnostic feature of absolute value—a feature as yet confined 
to this species alone. 
GENERAL DISCUSSION 
Because it differs, in the respects which have been discussed, from all 
other known conidial members of the genus, there is the more signifi¬ 
cance and interest in the fact that Sclerospora graminicola shows the 
same main features of nocturnal conidiophore production which char¬ 
acterize at least three of these other conidial species. This fundamental 
agreement in behavior, together with the general similarity in structure 
and development, is sufficient, in the opinion of the writer, to outweigh 
the difference in germination. It seems undesirable, therefore, to estab¬ 
lish a new genus on the species whose conidia germinate by hyphae, at 
least until much more extensive comparative study of the several species 
has given us further basis for such a rearrangement. Within the genus, 
however, there might be advantages in following Ito’s (ri) suggestion 
of establishing one subgenus, Eusclerospora, to include S. graminicola , 
and another, Peronosclerospora, to comprise the species the conidia of 
which germinate directly. 
Of the Sclerosporas with known conidial stages, four species, S. philips 
pinensis, S. spontanea , S. sacchari , and S. graminicola, alike have been 
found by the writer to be characterized by nocturnal conidiophore pro¬ 
duction. It will rest with future investigation to justify the natural 
assumption that this feature is common to all conidial Sclerosporas. It 
will rest with future investigation also to decide with finality what factor 
cr combination of factors is operative at night to induce conidiophore 
