704 
Journal o f Agricultural Research 
Vol. XXXT, No. 8 
of spores occurred at fairly wide intervals (10 to 40 y) at genic- 
ulations usually not very pronounced. 
Owing to the meager development of the fungus on the material 
obtained in the field, some of the diseased leaves were incubated in a 
damp chamber. A luxuriant growth of fructifications at once ensued, 
with the result that at the end of three days the leaves were covered 
with a profusion of conidiophores bearing an abundance of fresh 
conidia (fig. 1 , Ba to Bq). Pure, single-spore cultures of the fungus 
were obtained by the usual method of transferring individual conidia 
germinating in poured plates of plain agar to cornmeal agar plates, 
and then transferring portions of the resultant growth, free of con¬ 
taminating forms, to cornmeal agar in tubes. 
The conidiophores developed in a moist atmosphere on the natural 
substratum, as in related forms, are not sharply differentiated from 
the sterile hyphae. Usually they consist of branches or prolonga¬ 
tions of subhyaline or fuliginous mycelial filaments, differing from the 
latter in having a thickened wall dark olivaceous in color. As on 
the conidiophores found in nature, they develop spores in rather 
open arrangement, the individual conidia being attached at relatively 
wide intervals. Branching is not rare although it is more frequent 
in the sterile portions of the sporiferous elements. The sporophoric 
filaments, which often attain a length of 1 mm. or more, present, in 
mass, a brownish-black macroscopic appearance which may become 
brownish gray or even light gray, depending upon the quantity of 
subhyaline vegetative mycelium present as an admixture. 
The conidia of the fungus as produced on diseased maize leaves 
in a damp chamber (fig. 1 Ba to Bq) or on cornmeal agar in pure 
culture (fig. 2), are readily distinguished from those of Helmintho- 
sporium turcicum in shape, dimensions, septation, and basal modifica¬ 
tion. While the spores of the leaf-blight fungus are typically straight 
or slightly curved, widest at the middle and tapering markedly 
toward the ends, those of the leafspot parasite are typically strongly 
curved, the curvature being indeed more pronounced than in any 
large-spored congeneric form studied by the writer, and tapering 
moderately toward the ends. In respect to size, the conidia of the 
new foliar parasite appear markedly inferior to those of the other, 
measuring only 30 to 115 yin length and 10 to 17 y in diameter as com¬ 
pared witn 45 to 142 y and 15 to 25 ytor the ranges of the correspond¬ 
ing dimensions in H. turcicum. In spite of its inferior length, however, 
the conidia of the leafspot fungus are the more abundantly septate, 
the number of cross-walls not infrequently reaching the observed 
maximum of 12, while in all material of H. turcicum examined by the 
writer, these have never been seen to exceed 8. An additional differ¬ 
ence exists, inasmuch as in the fungus under consideration the hilum 
is represented by a broad flat scar not generally protruding from the 
rounded contour of the basal end of the conidium, while the basal 
segment of the spore of H. turcicum exhibits a narrow protruding 
apiculum. With respect to coloration the distinction is less marked, 
although the light or moderate olivaceous color characteristic of the 
mature conidia of the leafspot fungus is noticeably darker than the 
fuliginous tinge generally present in the conidia of the leaf blight 
parasite. The same mode of germination by the production of 
two germ tubes, one from the apical end, the other from the region 
surrounding the hilum, prevails m both species (fig. 1 , Ca to Ce) . 
