280 BOTANICAL GAZETTE [NOVEMBER 
No perithecia were found, but sclerotia were formed on auto- 
claved rice. These are dark gray and 500-1000 uw in diameter. 
Terminal chlamydospores are produced on 60-day old cultures. 
They are globular or oblong, with an average mean diameter of 14 p, 
and with a scarcely perceptible yellow tinge (fig. 45) 
CULTURE CHARACTERS.—Pure cultures are easily obtained by 
directly planting pieces of mycelium taken from the innermost 
portion of the mycelial mass. On cornmeal agar the rate of 
growth averages o.5 cm. daily at room temperature. The thallus 
is arachnoid and regularly zonated, the zones averaging 0.5 cm. 
in width. Aerial mycelium covers the entire thallus but is most 
luxuriant in the central area, and there it is tufted. On Brazil nut 
agar the growth is more dense and a little more rapid than on corn- 
meal agar, its rate being from o.7 to 1.0 u at room temperature. 
An extra-cellular, proteolytic enzyme is secreted, causing a halo 
of 3-5 mm. in width in the medium surrounding the thallus. The 
aerial mycelium is more luxuriant on this agar than on the other. 
The fungus grows vigorously on nut plugs, so that in a few days 
the plugs are enveloped with the snow-white mycelium, while a 
putrid odor is exhaled. After two or three months the plugs are 
completely reduced and only a mycelial mass remains. There is 
no color change on autoclaved rice until it shrinks away from the 
tube, when it is Maize Yellow. The fluffy, white, aerial mycelium 
surmounts the rice column and covers its sides as the growth 
proceeds downward. Apparently complete destruction of the 
rice is accomplished within two months. On carrot plugs the 
growth is not so rapid as on other media, but is marked by an 
abundance of white aerial mycelium. It is without color change. 
On the strip of nut meat above the water the growth is vigorous, 
and if the water surface remains near enough to the strip it is 
destroyed within eight or ten days. The strip in the water often 
appeared to be intact when it was not, the mycelium retaining the 
outline. It was probably destroyed as soon as the strip above. 
In hanging drop the conidia begin germinating after three or- 
four hours at room temperature, but many of them require twenty- 
four hours or more. Seldom more than two cells of a spore germi- 
nate, but frequently one cell produces two germ tubes (fig. 46). It 
often happens that spores are united by a short germ tube. Occa- 
