DAMPING-OFF IX FOREST NURSERIES. 55 
under ordinary nursery conditions is yet to be proved. The results 
in inoculations on disinfected soil, together with the frequency with 
which the fungus has been isolated from seedlings in the nurseries, 
lead the writer to believe that it is an important cause of disease in 
the seed beds. Further experiments on unhealed soil, however, are 
considered desirable. 
RHEOSPORANGIUM APHANIDERMATUS. 
CULTURAL STRAINS. 
A culture of a parasite on radishes and sugar beets, described by 
Edson (39) under the above name, was obtained from him, and an- 
other strain, shown by Edson's records to be a subculture from the 
same original strain, was furnished by the department of plant pathol- 
ogy of the University of Wisconsin. In parallel cultures on solid 
media this fungus proA^ed in many ways remarkably like Pythium 
debaryanum, reacting in practically the same way to the different 
media on which it was grown both in relative growth rate and in 
spore production. Mycelium, chlamydospores, oogones, anthericlia, 
and oospores are not recognizably different from those of Pythium 
debaryanum. The oospores have seemed on the whole slightly larger 
and the mycelium a little more inclined to aerial growth than most 
of the Pythium debaryanum strains, but neither difference was suffi- 
cient to have diagnostic value. Swellings of the hyphse occurred at 
points in contact with glass, just as with Pythium debaryanum (PL I, 
figs. 5 to 7). 
In liquid cultures the Eheosporangium was readily distinguished 
from Pythium by the formation of the presporangia described by 
Edson. Autoclaved cylinders of turnip, 15 to 20 mm. long, cut Avith 
a 5-mm. cork borer, proved convenient bases for growth of both 
Eheosporangium and Pythium in water culture and quite as satis- 
factory as sterilized beet seedlings. Presporangia were also pro- 
duced in autoclaved soil, and in a single lot of corn-meal agar they 
were formed abundantly in the agar in Petri dish cultures. In none 
of the writer's cultures, either with flies, sugar-beet seedlings, or 
turnip cylinders as nutrient bases, were mature escaped sporangia 
or swarm spores commonly produced. 
The Eheosporangium was not obtained in any of the numerous 
cultures made from coniferous seedlings or from seed-bed soil. 
INOCULATION EXPERIMENTS. 
The Eheosporangium cultures above referred to, strain 229 fur- 
nished by Dr. Edson and strain 351 received from the University of 
Wisconsin, were tested on pine and red-beet seedlings, with parallel 
inoculations with Pythium debaryanum. The results appear in 
Table VI. 
