726 
Journal of Agricultural Research 
Vol. XXIV, No. 8 
The correspondence in morphological features between the three forms 
is sufficiently close to warrant regarding them, at least provisionally, as 
specifically identical. To be sure, in respect to the dimensions of conid- 
iophore and conidium as well as to numerical range in spore septation, 
Breda de Haan’s {i6) account is not altogether in perfect agreement with 
Hori’s description; and either account reveals shortcomings when con¬ 
sidered in relation to the American fungus. However, if the more 
extreme and relatively infrequent expressions of length and septation 
are disregarded, the differences are not especially large. Perhaps the 
most serious discrepancy is found in diameter of condium, the measure¬ 
ments given in Hori’s account, i6 to 22 ju, exceeding the measurement 
given by Breda de Haan and also the measurements obtained from 
American material, by somewhat more than can readily be referred to 
ordinary variability, in view of the comparative constancy generally 
characteristic of this dimension within a particular species. Although 
Ideta's {6J) figures indicate that the Japanese fungus is at least of the 
same general type as the American form, a brief morphological account 
based on material from Louisiana nevertheless may not be superfluous. 
The black, velvety, mycelial mats on the glumes of affected spikelets, 
which are found distributed irregularly and usually rather sparsely 
through otherwise healthy panicles (PI. 30, A), are composed of prostrate 
hyphae and more or less erect sporophores. The former, which com¬ 
municate directly with the mycelium in the tissues of the host, when 
well developed, show abundant branching and anastomosis and are com¬ 
posed of short segments, dark brown or olivaceous in color, more or less 
inflated or lobulate, and measuring from 8 to 15 ju or more in diameter 
(PI. 30, D). The sporophores arise as lateral branches from these hyphae, 
which indeed they resemble toward the base, in possessing a dark oli¬ 
vaceous color, and in showing a tendency toward ramification. (PI. 30, 
D.) Some distance from their base, the sporophores gradually change 
from an olivaceous color to a light fuliginous hue, and at the tip may 
even be subhyaline. They vary in width from 4 to 8 iu, and in length 
from 150 to 600 IX or more, depending on the age of the growth. The 
scar marking the point of attachment of the first spore is found above 
the olivaceous proximal portion of the sporophore, usually not less than 
200 IX from the base; successive scars occur at relatively long intervals 
(10 to 90 m) at geniculations not always well defined or conspicuous. 
As collected on rice plants naturally infected, the conidia measure 
II to 17 in diameter by 35 to ix in length. The larger ones like 
those shown in Plate 30, C^, b, and containing as many as 13 septa, appear 
to be produced for the most part on well developed mats of sporophores 
occurring on the glumes; while the less extreme sizes (PI. 30, Cc, m) are 
associated with &e scattered fructifications on the glumes or leaves. 
Apparently because of the absence of the longer spores from diseased 
leaves, those of more moderate length have been regarded as character¬ 
istic of the parasite, the one figured in Plate 30, Cf, for example, fitting 
almost exactly the description given by van Breda de Haan. Typically 
the spores are slightly curved, widest at the middle or somewhat below 
the middle; the distal portion tapering toward the hemispherical apex 
where its width approximates half the median width; the proximal por¬ 
tion tapering toward the base, which is similarly rounded off, although the 
diminution in diameter is usually perceptibly less. When fully mature 
they are fuliginous or brownish and provided with a moderately thin 
peripheral wall that is further attenuated at the apex as well as imme- 
