272 
Journal of Agricultural Research 
Vol. XXV. No. 6 
from cultures growing in the ordinary laboratory light under tropical 
room temperatures. ■ 
Corn mejal. —At first the growth on com meal was very scant, being 
hardly recognized. The mycelium spread slowly and thinly in a circular 
area over the medium. Few, short, aerial hyphae were produced. In 
two to four days the growth was sparse and granular, due to the pro¬ 
duction of spores. As the culture grew older, the hyphae became more in 
evidence and a distinct granular appearance was formed. Finally a 
slight cottony, much granular growth developed over the surface of the 
com meal. An abundance of conidia and fewer chlamydospores were 
produced. 
Lima bean agar (ioo gm. lima beans, 20 gm. agar, 1,000 cc. water).— 
Growth started with few aerial hyphae that gradually spread over the 
surface of the agar slant. In three days the mycelium had nearly spread 
over the surface. It was then characterized by being aerial, white, 
cottony, and granular. The granular appearance, due to spore pro¬ 
duction, was more in evidence on the walls of the glass tube at the edges 
of the growth. As the culture grew older, there was a gradual thicken¬ 
ing of the aerial, mycelium mass. 
Oat meal agar (ioo gm. Quaker Oats, 17 gm. agar, 1,000 cc. water).— 
At first a few aerial hyphae developed which then gradually spread over 
the surface of the slant. After four days the mycelium, although still not 
very thick, had spread over the whole surface of the agar. Many granular 
bodies developed at this stage. The growth was exceedingly rapid 
and soon the mycelium formed a thick mass evenly spread over the agar 
slant, being slightly thicker at the base. As the culture grew older the 
hyphal mass gradually became more and more dense. Chlamydospores 
were produced in abundance and conidia were not so much in evidence. 
Potato dextrose agar (ioo gm. potatoes, 20 gm. dextrose, 15 gm. 
ag a r, 1,000 cc. water).—The first growth was characterized by being 
flocculent and submerged in the medium. On the second day, aerial 
hyphae appeared along with an increase of the submerged, flocculent 
growth. The aerial hyphae gradually became more dense and covered 
the entire slant. After five days the vegetation was dense, white, 
cottony, and usually thicker on the lower part of the slant. Minute 
granules formed by the spores were soon in evidence. Chlamydospores 
appeared to be produced first and in more abundance than the conidia. 
RELATION TO LIGHT 
In all of the cultures after exposure to the ordinary laboratory light 
for four days spores were produced copiously. If the cultures were 
kept in a dark chamber or incubator, free from light, only a few spores 
were formed. Sporulation was therefore hindered to a certain extent 
by darkness. There were apparently more chlamydospores than conidia 
produced in the dark. The growth in the light was more granular than 
that in the dark. 
RELATION TO TEMPERATURE 
Both strains of the fungus behaved the same in their relation to tem¬ 
perature. Altmann controlled temperature incubators ranging from 
about 4 0 to 32 0 were used for these determinations. A parallel series 
on potato dextrose agar plates was placed at the various tempera¬ 
tures and the difference in vegetative growth was determined by measure- 
