714 Journal of A gricultural Research voi. xxiv. No. s 
Equally severe epiphytotics apparently are not uncommon in the 
Philippines, where Reinking (117) found the disease sometimes extremely 
destructive, entire plots of field corn and sweetcorn having been ruined 
by it. 
Several weeks after the initiation of a foliar lesion, when the affected 
tract usually exceeds 5 cm. in length, a grayish, greenish efflorescence 
makes its appearance in the center of the withered area, becoming gradu¬ 
ally more extensive with the continued enlargement of the latter. This 
efflorescence consists of the numerous fructifications of the fungus, 
which, in spite of the statement of Cooke and Ellis (24), are more readily 
perceived with the naked eye than the fructifications of the majority of 
the species of Helminthosporium developing on the foliage of grasses. 
When such material is examined under the microscope the fructifications 
can be seen emerging in groups of 2 to 6, always from the stomata. The 
olivaceous conidiophores (PI. 24, Ca~g) usually measure from 7.5 to 9.0 /x 
in width, although Saccardo (i28y v, 4, p, 420-421) gives 6 ^ for this 
dimension. His characterization of these structures as “ 3-pauciseptatis'' 
is more nearly correct, as the number of septa varies usually from 2 to 4. 
As the sporophores have been found to attain a length of 260 (PI. 24, Cf) 
or more, Saccardo's (128) figure, 150 ju, being apparently a decided 
understatement of this dimension, the intervals between the septa, 
compared to those of most other species, are relatively large. 
The spores of the fungus, which are quite characteristic, have been 
described and figured in a great variety of ways, but rarely altogether 
correctly. As shown in Plate 24, Ba-p, drawn from material derived 
from diseased leaves of sweet com collected on Long Island, they vary 
considerably in size and shape. The measurements for length and 
width, ranging from 45 to 132 /x (PI. 24, Bl, o) and from 15 to 25 ^ (pi. 
24, Bi, o), respectively, agree fairly well with those given by other 
authors: Saccardo (128) 85 to 92 by 20 to 24 fx; Ducomet (54) 65 to 95 
by 20 to 25 /x; Cooke and Ellis (24), and Schwarze {130) 80 to 120 by 
20 ju; Butler (19) 80 to 120 by 20 to 24 ju; and Massee (90) 80 to 140 by 
20 to 26 fi. In shape the spores are typically straight or slightly curved, 
widest near the middle and tapering decidedly toward the ends. The 
proximal portion of the spore may taper toward the hilum somewhat 
in the manner of a cone (PI. 24, Bf, h, k) although a tendency toward the 
basal end being rounded off usually is discernible (PI. 24, Bb, i) and not 
infrequently quite pronounced (PI. 24, Bm, n). In any case, however, 
the shape defined by Saccardo as ‘‘perfecte fusoideis utrinque acutis’^ is 
never realized, because the apical end of the spore is always rounded, 
even where the distal segment is very considerably inferior in width to 
the middle segment. Certainly, conidia like those figured by Saccardo 
{i26y pi. 824) with the basal and apical ends drawn out into attenuated 
beaks, have never been observed by the writer. Nor have any been 
observed entirely comparable with those figured by Massee, with the 
acumination of the ends considerably exaggerated and the septation so 
close that the segments appear more than twice as wide as they are long. 
On the other hand, Schwarze’s (150) figures represent them as rather too 
blunt, a fact for which the evident use of dead herbarium material may, 
perhaps, largely be held responsible. 
The number of septa in the spores was found to vary from i to 8 in the 
material collected by the writer. Inasmuch as the i or 2 septate indi¬ 
vidual spores are manifestly undersized, the correspondence with the 
numbers given by most authors is, on the whole, satisfactory—Saccardo 
