408 
Journal of Agricultural Research 
Vol. XXX, No. 5 
agar, beech-decoction agar, and on 
sterilized beech branches. Large test 
tubes about 1 inch in diameter and 12 
inches long proved to be most satis¬ 
factory for this work. As only one of 
the first cultures growing in small 
test tubes developed the basidial stage, 
other single-spore cultures were trans¬ 
ferred to the large test tubes. These 
cultures were kept at room tempera¬ 
tures at first, but later some of them 
were placed in the refrigerator. 
CHARACTERISTICS OF THE FUNGUS 
IN CULTURE 
The basidiospores germinate in the 
manner described by Brefeld ( 6 ). The 
hyphae with their much branched con- 
idiophores and luxuriant development 
of conidia have been so adequately and 
accurately described and figured by 
this author that further space need not 
be given to this phase of the question, 
except to call attention to certain char¬ 
acters not fully brought out by him. 
The mycelium in mass is not yellowish, 
as he describes. The production of 
conidia begins within a few days, and 
as soon as they cover the surface the 
color of the culture on potato-dextrose 
agar is Prout’s brown, while on corn- 
meal agar it is Verona to sepia brown. 4 
Grown on pieces of beech branches, the 
culture becomes covered with a great 
felty mass of mycelium and conidia, 
nearly Prout’s brown in color. The 
mycelium grows very slowly; a colony 
several weeks old may not be over 
2 cm. in diameter. 
The fact that basidia, which are not 
easily recognized because of their form 
and manner of septation, are not devel¬ 
oped in a hymenium and that their 
spores after becoming detached lie en¬ 
tangled among the loose hyphae of the 
head, has led some of our mycologists 
to a misconception as to the nature of 
the sporocarps. The hyphomycetous 
conidial stage which Brefeld first de¬ 
scribed and which always develops in 
cultures with the production of masses 
of conidia (pi. 2, A to C) comprises a 
phase in the life history entirely distinct 
from the basidial fructification. 
After the first cultures had grown in 
12-inch test tubes in the laboratory at 
room temperature for about four 
months, little flecks of pure white 
hyphae developed in several of the 
tubes. These growths increased in 
size, being at first rather indefinite in 
shape, but soon resembling very small 
mushroom buttons. The stipelike por¬ 
tion became surmounted by a small 
head. After two weeks some of the 
white growths began to turn grayish. 
These were removed and found to con¬ 
sist of hyphae having clamp connec¬ 
tions. Basidia were developing from 
these hyphae in much the same way as 
figured by Brefeld. The basidiospores 
are nearly spherical, and being some¬ 
what larger than the conidia they were 
easily distinguished from them. Bre¬ 
feld has given adequate figures of the 
basidium and its spores. It is a true 
basidium having a definite number of 
spores, four in each case, just as 
claimed by him. 
The first cultures, which were iso¬ 
lated November 5, 1923, fruited the 
following February, having meanwhile 
developed merely the gametophyte 
mycelium which produced only conidia. 
Sixteen monosporous cultures were 
transferred March 10; on June 5 it 
was found that most of the cultures 
showed the white patches of mycelium, 
which indicates that clamp connections 
are being formed and that basidia will 
soon develop. Ordinarily it requires 
about three months for the cultures to 
mature fruit bodies. One culture on 
potato-dextrose agar showed nearly 100 
separate masses of white mycelium. 
Each mass represented an incipient 
fruit body covered with the ash-gray 
“gleba” in which quantities of basidio¬ 
spores were being produced (pi. 1, B). 
Cultures in which two monosporous 
strains in various combinations were 
grown did not produce the basidial 
fruiting stage in any greater abundance 
than did the single spore cultures. 
Fully as many fertile heads developed 
on cultures from one spore as were 
formed in cultures representing several 
strains. 
No definite fruiting body such as 
characterizes Pilacre when it grows in 
nature on beech logs was developed in 
some of the cultures, although large 
numbers of basidia were formed in loose 
aggregations of hyphae. In other cases, 
however, fruiting bodies 2 or 3 mm. 
high were developed, some of them pos¬ 
sessing a definite structure, consisting 
of a stipe surmounted by the expanded 
fertile head. The sporophytic hyphae 
of those which eventually produce 
basidia are pure white until the devel¬ 
opment of spores begins. The head 
then turns ash-gray as noted. Clamp 
connections are always found on the 
hyphae developing basidia. They also 
occur on the hyphae composing the so- 
called “peridium” (pi. 2, Q). 
Wherever basidia are formed the 
hyphae producing them are clustered 
4 Ridgway, R. color standards and color nomenclature. 43 p., illus. Washington, D. C., 1912. 
