718 
Journal of Agricultural Research 
Vol. XXXI, No. 8 
the fruiting body has the appearance of a superficial structure (fig. 4, A, 
upper). In some instances the rupturing of the disintegrating host 
tissues is delayed longer, while in the case of perithecia developing 
on the filter paper over which the fungus spreads from infected ma¬ 
terial, even the earlier stages are practically superficial, the loose mat 
of overlying fibers scarcely affording any substantial covering. The 
globose portion of the perithecium attains its definitive size in about 
6 to 10 days, and a few additional days are usually required for the 
beak to reach its final proportions. Externally the fruiting body is 
black and relatively smooth, though often beset toward the base 
with stubby cylindrical projections resembling incipient conidio- 
phores, or, perhaps, the proximal part of fractured conidiophores. 
The dark pseudoparenchymatous external layer is relatively thin, 
while the interior consists at first of firm colorless pseudoparenchyma 
composed of laterally appressed, vertically oriented filamentous ele¬ 
ments. Young asci can generally be made out here and there after 
12 days, and at the end of 15 days are not at all rare. As the asci 
increase in size and number the pseudoparenchymatous structures 
diminish correspondingly. Perithecia from 18 to 20 days old gen¬ 
erally yield, on being crushed, a small proportion of approximately 
mature asci; the condition illustrated in Figure 4, B (lower), where 
most of the asci are mature, being, however, not attained usually in 
less than 25 or 30 days. 
The mature asci, except for the short, markedly contracted stipe, 
are roughly cylindrical in shape, though generally widest about one- 
third of their length from the base, from which point the diminution 
in diameter toward the apex is more gradual than toward the base. 
When crushed out individually they frequently show more pro¬ 
nounced distention, evidently as a result of the imbibition of water 
preliminary to dehiscence, when such imbibition takes place in the 
absence of pressure normally provided by the surrounding asci and 
filamentous elements. Those m the center of the fruiting body are 
usually straight, while others near the periphery are distinctly curved, 
to conform with the curvature of the subspherical perithecial wall 
(fig. 5, A). Each ascus contains typically four cylindrical ascospores 
coiled in a close helix, each spore usually exhibiting approximately 
four turns, which alternate regularly with the turns of the other spores. 
As the lower ends of one or more spores thrust well into the short 
contracted stipe the helicoid arrangement at the base of the ascus is 
constrained into some* irregularity. The upper ends of the spores 
similarly thrust into the apex of the ascus, yet, owing apparently 
to the more regular conformation of the apical portion, the departure 
from the spiral arrangement is usually very slight. In several hun¬ 
dred asci examined the rotation of the helix has been found to be 
always in the same direction; that is, on an upper focus with the 
ascus in a horizontal plane following the spore from the base toward 
the apex the coil appears at right and disappears at the left. The 
four spores might thus be compared to the threads of a quadruple 
left-handed screw. 
The earlier stages in the development of the ascospores are not 
easy to make out, at least in unstained preparations, as the young 
structures are distinguished in the granular protoplasm only with 
difficulty. The spores first become clearly visible in the still growing 
ascus as filamentous bodies, approximately 3 [x in diameter and about 
