484 
Journal of Agricultural Research 
Vol. XI, No. 10 
specimens were kept under observation through the remainder of the 
winter and spring months. Pycnidia and pycnospores were found from 
time to time, as well as an increasing number of stylospores. On June 2 
pods brought into the laboratory bore a considerable number of mature 
perithecia of an ascomycete, which was identified as Diaporthe phaseo- 
lorum (C. and E.) Sacc. The writer was away for five weeks previous to 
June 2 so it is not certain just when the development of perithecia began, 
and for that reason it was not possible to follow the complete course of 
development. The perithecia are scattered and buried beneath the 
surface, most of the beak protruding. Plate 43, D and F, shows dia- 
grammatically the arrangement of the perithecia and relatively the 
depth they are sunken below the surface. Whether or not the perithecia 
are all formed in the cavities of old pycnidia has not been definitely de¬ 
termined. The pycnidia are rather numerous 
and often coalesce, and as a matter of chance a 
perithecium might preempt a pycnidium and be 
formed therein. It is believed, however, that 
this is not the rule. The perithecia are not irregu¬ 
lar in shape, as might be expected if they were 
formed in old pycnidia; but they usually bear a 
rather definite and constant form (PI. 43, F). 
They also have separate and distinct walls which 
i?ig. 8.— Diaporthe phaseoio- <j[iff er from the layers of the pycnidium. In no 
spores. X500. case have the spores or stylospores ever been 
found associated with a perithecium, although 
these bodies were present on the host at the time. 
The perithecia are slightly flattened, 158 to 355.5 ju, average 251.9 /i 
in width and from 110.6 to 205.4 average 166.5 m in depth. The beaks, 
many times longer than wide, are usually curved or hooked (Pi. 43, D), 
rarely straight, tapering gradually to the end. The perithecium, circum¬ 
scribed by a dark layer of cells, is lined within by a thin, hyalin layer 
from which the asci arise. The perithecium is evidently almost or 
completely matured before the beak is formed. Plate 43, D, shows 
beaks just appearing through the epidermis. Sections through peri¬ 
thecia with beaks in the incipient stage show the wall layers to be per¬ 
fectly formed and many mature asci present. The asci (fig. 8, a) are 
sessile, clavate or fusoid, 28.0 to 46.2 n by 5.2 to 8.0 ii t numerous, 
and contain eight spores arranged mostly biserially. The ascospores 
are apparently bound together or embedded in a gelatinous mass, since 
they are firmly held together even after the apparent disappearance of 
the ascus wall. The ascospores, (fig. 8, b) measuring 6.4 to 12.0 by 2.3 
to 4.0 ix, are spindle-shaped, oblong-lanceolate, 1-septate at or near the 
center, slightly or not at all constricted, and contain two to four oil 
droplets. 
