718 
Journal of Agricultural Research 
Vol. XXIV, No. S 
the spores of the latter type have exhibited the irregularity in question. 
When such conidia germinate, the surviving segments collectively pro¬ 
duce I or 2 polar germ tubes, which traverse the neighboring dead 
segments and their degenerate swollen envelopes like so much inert 
material, to emerge usually, though not always, from the ends of the 
spore. In conidia of which all segments are in a living condition, the 
juxtaposed portions of segment membranes that constitute the septa 
normally undergo no degeneration; at least until the germ tubes have 
attained extensive development. 
HELMINTHOSPORIUM LEERSII ATKINSON 
In 1897, Atkinson (4) described as Helminthosporium leersii, a fungus 
collected on leaves of Leersia virginica Willd. { — Homolocenchrus vir- 
ginicus [Willd.] Britton) at Auburn, Ala., September 13, 1891: 
Spots irregularly oblong, amphigenous, at first dark brown, then dirty white with 
dark brown border. Hyphae amphigenous, brown, irregularly nodulose or flexuous, 
200 to 350 by 4 to 6 M- Conidia slightly curved, 5 to 9 septate, elliptical, faintly 
fuliginous. 
Although the form was later included in Earle’s list of Alabama fungi 
(92), it seems to have escaped the attention of botanists in other states. 
Nevertheless, the parasite appears to be widely distributed, as the writer 
found it of frequent occurrence on the leaf blades of L. virginica 
near Meriden, Conn., in September, 1920, as well as in the vicinity of 
Washington, D. C., during the summer of 1921. 
The first indication of attack becomes evident as a minute brown spot 
often not exceeding i mm. in length. (PI. 26, A, C.) As this spot 
enlarges, the central area for some time remains dark brown, while the 
discoloration at the margin merges insensibly into the light green of the 
surrounding healthy tissue. With further increase in size, the tissues 
in the center succumb, their dark brown in the meantime fading to a 
dirty straw color. As the line of demarcation between the gray central 
region and the peripheral brown zone is sharply defined, a foliar lesion of 
the eye spot type (PL 26, A, C) results. The parasite seems to hasten, 
if not to cause, the death of the older leaves. When the latter have 
withered, either in whole or in part, the fructifications make their appear¬ 
ance, scattered sparsely, first near the center of the spot but later also 
beyond the margin. 
According to Atkinson (4) Helminthosporium leersii is ‘*near H. 
turcicum but hyphae and conidia more slender.” It seems questionable 
with which one of a number of congeneric organisms this author intended 
to compare the fungus. Certainly, no striking similarity to the parasite 
causing leaf blight of maize is discernible with respect either to the 
dimensions or to the shape of spores and sporophores. In the material 
collected by the writer, the latter were found to arise singly or more 
rarely in pairs from between the epidermal cells of the host. (PI. 26, 
Fa, b.) The moderately fuliginous conidia (PL 26, Ba-i), measuring 
from II to 14 ju in diameter by 50 to 95 /i in length, were found to con¬ 
tain from 3 to 12 cross walls, never associated with perceptible con¬ 
strictions in the unusually thin peripheral wall. Irregularities in the 
insertion of cross walls, resulting in muriformly septate conditions are 
present as in the spores of H, sativum. (PL 26, Bk.) As in H. sativum 
also, germination normally takes place by the production of two polar 
germ tubes. (PL 26, Da-c.) However, owing to the fragility of the 
