316 
Journal of Agricultural Research 
Vol. I, No. 4 
culture (strain 33) and covered with bell jars. An uninoculated check tree was cov¬ 
ered in the same way. The trees were sprinkled twice between June 15 and 20, and 
the bell jars were removed on the latter date, at which time definite infection was noted 
on the first inoculated tree, but none was on the second or on the check tree. An 
accident to these trees prevented further observations. 
Experiment No. ii (Dec. 18, 1912).—The partly mature leaves of a seedling 
pecan were inoculated from an 8-weeks-old com-meal-agar culture (strain 113). This 
and one check tree were left under a bell jar for three days, when tiny reddish brown 
specks could be recognized over the inoculated areas. After bleaching and staining, 
these leaves were examined for the mode of entrance of the fungus into the leaf. 
Many cases were found in which the mycelial threads had passed through the open¬ 
ings in the stomata. In all probability this mode of infection occurs in the field from 
the germination of the spores, but this point has not been proved by artificial infection, 
on account of the lack of distinct coni dial formation in culture. 
Cultural Studies 
THERMAL TESTS 
Several series of com-meal-agar slant cultures were grown for two to 
three weeks in constant-temperature incubators ranging from 1 0 to 40° C. 
No growth took place below 5 0 or above 35°. After two to three weeks' 
incubation growth at 8° had barely started, while the rate gradually 
increased up to 30° (86° F.), this giving the highest rate for the tem¬ 
peratures tested. Growth at 32 0 was about the same as at 14 0 . Cul¬ 
tures incubated two to three weeks at 36° and 40° gave no signs of life 
when subsequently held at room temperature, while those incubated at 
2 0 and 4 0 made a perfectly normal growth when placed under favorable 
conditions. 
cultural characters 
The cultural characters of the fungus as grown upon several of the 
more common media are briefly described below. No distinct develop¬ 
ment of conidia has been observed in cultures of the fungus. 
Beef-Agar Slant Tubes.—The colonies are convex, approximately raw umber 
in color, glistening and smooth at first, but later becoming wrinkled and finally attain¬ 
ing a diameter of 10 to 12 mm. Aerial mycelium where present has been very sparse. 
The submerged mycelium consists of a pale-olive, tangled mass of hyphae with many 
swollen and contorted cells. 
Beef Broth.—The entirely submerged and dirty-whitish colonies consist of a 
rounded filmy mass of threadlike mycelium with but few swollen cells. Some of the 
hyphae are beaded in appearance. 
Corn-Meal-Agar Slant Tubes (PI. XXXVII, fig. K ).—The submerged growth which 
is usually the most prominent part is seal brown to black, while the somewhat cottony 
aerial mycelium is pinkish. After an incubation of one to two weeks a distinct violet 
tinge is assumed by the whole agar plug, and the combination of pigment and gela¬ 
tinous medium gives an opalescent appearance to the whole. Colonies often reach a 
diameter of 15 mm. Except for the rather scant aerial mycelium, the growth is entirely 
below the surface of the medium where the hyphae consist of more or less distorted, 
dark olive-brown cells. 
Corn-Meal Flask Cultures.—The colonies are cottony to plushlike in surface 
appearance, with a wide variation of color comprising white to pale pink in the cottony 
parts and shades of raw sienna, burnt umber, and Venetian red elsewhere. A diameter 
