7o8 
Journal of A gricultural Research 
VoL XXIV, No. 8 
The conidiophores, as occurring in nature (PI. 22, Ef, g) or developed 
on the natural substratum in a damp chamber (PI. 22, Ea-e), are some¬ 
what inferior in diameter to those found on barley leaves affected with 
spotblotch and generally noticeably shorter. The conidia are of the 
same type as those of H, sativum. As found on material collected in the 
field (PI. 22, Ba-f), however, they are usually more narrow and not as 
regularly crescentic, being more frequently straight or irregularly curved. 
In color they are usually brownish yellow instead of olivaceous. In a 
certain proportion of the spores, moreover, the end cells are less deeply 
colored and the basal and distal septa appear conspicuously darker or 
heavier than the intermediate cross-walls. (PI. 22, Bd-f.) "'^en devel¬ 
oped in a damp chamber on diseased host material the conidia approach 
those of H, sativum in depth of coloration; but the distinction between 
dark intermediate segments and subhyaline or fuliginous end segments 
set off by conspicuously accentuated septa becomes a constant charac¬ 
teristic. (PI. 22, Da-f.) And while the apical end is rounded off quite 
abruptly as in H, sativum, the proximal end shows a more perceptible 
tendency to taper, recalling in some instances the decidedly acuminate 
contour of the proximal portion of the spores of H, monoceras. As in 
the latter species, this gradual tapering is associated with a hilum that 
protrudes from the basal contour of the conidium. 
In the species parasitic on Distichlis spicata the peripheral wall of the 
conidium varies more or less in thickness, depending apparently on the 
conditions under which the fructifications are developed. The darker, 
more mature conidia usually possess a peripheral wall which, if not as 
massive as in Helminthosporium sativum, nevertheless is of at least 
moderate thickness. As in H. monoceras, the wall is very thin at the 
apical end and over a narrow zone at the proximal end immediately 
adjacent to the hilum. Germination regularly occurs by the production 
of two polar germ tubes, one from each of these thin-walled regions. 
(PI. 22, Ca, e, i.) In the case of immature spores and often in the brown¬ 
ish yellow ones found in nature the peripheral wall is thinner, frequently 
collapsing when the contents of the segments inclosed degenerate. Such 
spores may germinate by the production of lateral germ tubes from one 
or more of Ae intermediate segments as well as from the end segments 
(PI. 22, Cb, c, d, f, g). This mode of germination ,however, can scarcely 
be regarded as typical for the species. 
The fungus is cultivated readily on artificial media, producing a lux¬ 
uriant dark olivaceous aerial groA^, consisting of a variable quantity of 
mycelium bearing an abundance of sporophores. When grown on tap- 
water agar, the fructifications (PI. 23, A-C) resemble those developed on 
parts of the diseased host after incubation in a damp chamber. The 
spores (PI. 23, B, D-G), which are attached at short intervals on the 
very irregular sporophore at wide angles and in moderately compact 
racemose arrangement, however, are usually perceptibly shorter. As 
in Helminthosporium sativum, the conidia frequently exhibit irregularities 
in shape, including flattening or bifurcation of the apical portion. (PI. 
23, D, F.) 
Besides resembling in some details the different species which have 
already been mentioned, the fungus suggests comparison with Hel¬ 
minthosporium leersii, and perhaps more especially with H, oryzae and 
H, rostratum. From H, leersii it may be distinguished readily by the 
subhyaline end segments, the accentuated end septa, and the protruding 
hila characteristic of its spores. While H. leersii on artificial media 
