126 
The results from this preliminary work indicate also a very wide dif- 
ference in the susceptibility of these cereals to rot by the various strains 
of Helminthosporium. Oats, on the whole, are less injured by them 
than any of the other four cereals tested. Corn and wheat were most 
often first in susceptibility to certain of the strains, and were also highly 
susceptible to more strains than were barley and rye. 
Seedlings in Petri dishes imoculated—Aseptic wheat-seedlings were 
placed on moist filter-paper in sterile Petri-dishes and were inoculated in 
their basal region in three ways: by placing upon them (1) wheat tissue rot- 
ted by H. No. 1 (pure culture), (2) conidia of this organism, and (3) agar 
bearing an abundance of growing mycelium. No difference was observed 
in the effectiveness of the three modes of inoculation. Each gavea 100% 
infection, always visible with a hand lens in 2 days (Fig. 16) as a small spot, 
which could usually be seen at the same time without a glass. A longer 
time than two days was necessary to demonstrate that this spot would 
develop into a general rot, but so it did in all cases when the environ- 
ment was favorable. 
Seedlings in rag doll inoculated—Wheat seedlings with shoots 2-3 cm. 
long were placed in a special form of rag doll (Pl. XX XIII) and inoculated 
with H. No. 1 by placing an oese of conidia-suspension on the base of each 
shoot without wounding. Infection was apparent to the naked eye in 
every case in two days, and the results in six days are shown in PI. 
XXXIV. Rotting occurred in 6-12 days under favorable conditions. 
At 6 days the roots were often more or less blackened for long distances and 
the cortex filled with mycelium. Views of cross-sections showed a heavy 
infection of the second leaf, and the sheath completely occupied. With 
excessive moisture, seedlings were killed by the Helminthosporium in 6 
days; but if in comparative dryness, only small lesions resulted. Seedlings 
similarly placed in rag-doll but atomized with conidia-suspension also gave 
100% infection, and the infection was much more widely distributed. 
Inoculation by diseased tissue or by fungus-bearing agar was in no way 
superior to inoculation with conidia. 
Control, or check, rag-dolls, made in the same manner but without 
inoculum, at 2 and 6 days showed no lesions even under microscopic ex- 
amination. In a very small number of cases there was infection by Hel- 
minthosporium in the checks, and in a few instances overgrowth by a 
Helminthosporium similar to H. No. 29, with geniculate conidia. 
Roots of wheat inoculated —Conidia of H. No. 1 were placed on the root- 
hairs of wheat-seedlings in rag doll. At the end of 4 days all roots so in- 
