700 
Journal of Agricultural Research 
Vol. XXIII, No. 9 
The discharge of spores from an apothecium was repeatedly observed. 
This appears to be brought about by a sudden change in the humidity 
surrounding them. When a good “crop” of apothecia have reached 
maturity in one of the flasks, as shown in Plate n, B, or in any other 
moist chamber in which they have developed, opening the chamber 
to the air by removing the stopper or otherwise will result in the sudden 
discharge of a cloud of spores. This phenomenon may not be observed 
again until the chamber has been closed for several hours and again 
opened, when it will be repeated. 
Many ascospore isolations were made by placing a mature apothecium 
on its side on a poured plate of clear agar with the disk facing the center. 
When the apothecium is left there for a few hours, the removal of the 
cover causes the sudden discharge of ascospores, which may be carried 
the full width of the plate. After such an occurrence the deposit of 
spores can sometimes be clearly seen with the naked eye on the surface 
of the agar, so thick are they. Microscopic examination of one such 
plate disclosed the interesting fact that often all eight spores from a 
single ascus when discharged clung together as if in a gelatinous matrix. 
Large areas on the plate were covered with groups of eight spores. 
Plate io, D, is a photomicrograph taken with a Zeiss 2.5-mm. water- 
immersion objective placed directly over one of these areas on the 
plate. Ascospore discharge also takes place either intermittently or the 
spores may be scattered when ejected, for spores may be found on the 
plate either singly or in groups of two or three. By examining the 
plate through the bottom with a low-power objective near the edge of 
the wedge-shaped area in front of the disks, it is an easy matter to locate 
as many spores as may be desired and mark them for transfer to another 
plate or a tube. 
Ascospore germination takes place very quickly on a plate of agar. 
Normally it is by the production of a germ tube which continues to grow 
vegetatively until conidiophores arise, and the gray mold stage is formed, 
which is usually within 36 hours. In one case, when such a plate as the 
one just described was held in the ice box over night, it was observed 
that microconidia were being produced on the ends and sides of compara¬ 
tively short genn tubes. This condition is pictured in Plate 10, C. 
The microconidia continued to develop during the day, a succession of 
them being borne on the end of a single conidiophore, until quite a group 
of them were to be seen. In no case could germination of microconidia 
be seen. The same plate shows normal germination of ascospores by 
germ tubes. This is also shown in various stages in Plate 12, H and I, 
which consists of camera-lucida drawings of spores from which the 
first ascospore cultures were derived.' 
DESCRIPTION OF THE FUNGUS 
For the convenience of the reader the complete description of the 
fungus, as published in 1919 (10 ), is repeated here. 
sceerotinia ricini 
Apothecia one to several from a single sclerotium, 5 to 30 mm. high, usually 6 to 
15 mm., infundibuliform to cyathiform and discoid, long stipitate, cinnamon brown 
to chestnut brown; stalk concolorous, cylindrical, slender, smooth, flexuous, attenu¬ 
ated below, without rhizoids; disc at first closed, expanding to saucer-shaped with 
margin sometimes recurved, exterior roughened, 1 to 7 mm. m diameter, usually 1.5 
to 4 mm.; asci cylindrical to cylindro-clavate, apex slightly thickened, opening by 
