402 
Journal of Agricultural Research 
Vol. VII, No. 9 
on May io in 1915 and on May 21 in 1916. In each case this was 
just after the host plant had begun to flower. 
The sclerotia of Claviceps paspali when mature are globular in shape, 
2 to 4 mm. in diameter, irregularly roughened on the surface, and yel¬ 
lowish gray in color; the interior is homogeneous in structure and con¬ 
tains a considerable quantity of oil. ’ Germinating sclerotia produce 
from one to several stromata, usually two or three, with slender whitish 
stalks 3 to 15 mm. in length, and heads about 1 mm. in diameter (PI. 
32, E). The heads are roughened over the surface owing to project¬ 
ing perithecial necks (PI. 32, A, E), and are at first whitish in color, later 
becoming rather bright yellow, and finally brownish. 
A vertical section of a stromatic head (PI. 32, A) shows numerous 
flask-shaped perithecia embedded in the outer part of the head. The 
neck of each perithecium projects a short distance beyond the surface, 
thus forming small pimple-like projections. Each 
perithecium contains numerous slender, cylindrical 
asci, 150 to 170M in length (fig. 1, a ); at the outer end 
of each ascus there is a thimble-like knob fitting over 
the end. The wall of the ascus is so thin that it can 
not be distinguished clearly. The ascospores are fili¬ 
form and hyalin, being a little less than iju in diameter 
and 70 to ioofi in length (fig. 1, c). There are 
probably eight spores in an ascus, although not more 
than seven were counted with certainty. It was not 
possible to count the spores when inside an ascus, as 
they are hyalin and packed together closely, and it 
was a rather difficult matter to count them as the 
ascus disintegrated. 
Mature stromatic heads from sclerotia just gathered 
from the field when allowed to dry slightly and then 
moistened exuded asci very freely. The asci go to 
pieces quickly after escaping from the perithecia and liberate the spores. 
A change of moisture conditions in the field will cause spores to be 
deposited on the surface of the stromatic head, where they are in 
position to be picked up by insects that chance to rub against the 
head. The stromata are somewhat tough and leathery and last for sev¬ 
eral days. If the ground becomes dry during their regular period they 
dry out, but revive with the coming of moisture and again shed spores. 
No stromata were found in the field after July 2. 
Flowers of Paspalum dilaiatum inoculated with ascospores by rubbing 
stromatic heads against stigmas and spikelets of the grass heads showed 
abundant evidence of infection in seven days. Flowers on control plants 
showed no infection. (Both inoculated plants and controls were kept 
under bell jars.) In the field, infected heads are not found for several 
days after the sclerotia germinate. They were first noticed on June 8 in 
Fig . 1 . —Claviceps paspali: 
a, Mature ascus; 6,ascus 
breaking up to liberate 
spores; c, ascospore. 
