3 i° 
Journal of Agricultural Research 
Vol. I, No. 4 
been observed, and swollen cells are commonly scattered here and there through the 
mycelium. Colonies often cover the slant, but unlike those on beef agar they are 
seldom much wrinkled. 
Corn-Meal Flasks.—On this medium the colonies with i or 2 months’ growth attain 
a diameter of 5 or 6 cm., and become deeply convoluted or wrinkled. The cottony 
aerial mycelium where present is similar in color to that on corn-meal agar, while 
the underlying pseudoparenchyma en masse takes on a yellowish bumt-sienna tinge. 
Pycnidia were not observed. 
Filter Paper.—Growth on filter paper moistened with sterile distilled water gave 
small colonies of a pale-violet color and with or without a scant pinkish white aerial 
mycelium. 
Oxalic-Acid-Agar Slant Tubes.—The colonies are raised to convex, pale ocherous 
around the margin and approaching a sepia brown throughout most of the central 
portion. With age the vegetable dye of the medium becomes bleached, so that the 
color of ordinary beef agar is finally assumed. No pycnidia were observed. 
Synthetic-Agar Slant Tubes 1 (PI. XXXVII, fig. G ).—The colonies are very convex, 
with moist and glistening surface. The mycelial mass is extremely viscous, much 
convoluted, burnt sienna to brown in color, and with the drying out of the cultures 
assumes various shades of olive green, violet, brown, and reddish brown. Numerous 
cross connections between the hyphae were noted, but no pycnidia have yet been 
developed on this medium. 
Morphology and Taxonomy 
Several of the diseased spots from fresh material were killed in Carnoy’s 
fluid, embedded in paraffin, and sectioned both vertically and horizon¬ 
tally in order to locate the course of the fungous growth within the 
tissues. The mycelium was found to be septate, very fine, and nearly 
or quite hyaline; and even in the stained vertical sections it was often 
distinguishable with difficulty. This readily explains the fact that 
examination of rough mounts from field material rarely gives any evi¬ 
dence of fungous growth within the leaf tissues. The mycelium was 
best located in the stained horizontal sections, where it could be dis¬ 
tinctly seen ramifying through the intercellular spaces just above the 
lower epidermis and throughout the mesophyll tissue. (Tig. 2.) Where 
the spots involved the vascular tissue, the hyphae were often seen extend¬ 
ing immediately parallel to the vessels, the latter in such cases being 
dead and discolored. In many cases this intercellular mycelium had 
developed scattered swollen cells with large vacuoles, but thus far no 
definite formation of pycnidia has been observed upon artificially infected 
leaves. Upon field material, however, the tiny dark-colored fruiting 
bodies are occasionally encountered upon the upper leaf surface. 
In 1887 a Phyllosticta occurring on Carya alba was described by Peck, 2 
which from his description and an examination of type specimens, 
appears to be identical with the nursery-blight fungus. Peck’s descrip¬ 
tion is as follows: 
1 For the formula for preparing synthetic agar, see p. 307. 
2 Peck, C. H. Plants not before reported. 40th Ann. Rpt.. N. Y. State Mus. Nat. Hist., 1886, p. 57. 
1887. 
