26 THE WHITE-FUNGUS DISEASE IN KANSAS. 
was too small to warrant any definite conclusions. The results, how- 
ever, indicate that chinch bugs may survive the injury made by the 
pipette, that direct inoculation into the body is more surely followed 
by infection than exposure to spores placed only on the surface of 
the body, and that introduction of spores into the abdomen gives a 
larger proportion of infections than inoculation into the leg. 
One series is given below as an example of the method employed. 
It differs, of course, from the natural one, but the technique is of 
service in testing the conditions of infection, as the virulence of 
spores grown artificially on culture media or the resistance of insects 
kept under different conditions or in different stages of growth. 
All chinch bugs used in the experiments were taken from the same 
lot, and all were inoculated with an emulsion in physiological salt 
solution of spores of Sporotrichum globuliferum taken from a 21-day 
agar culture. 
Twelve or more insects are included in each group. This culture 
was one derived from a series of transfers beginning with an original 
transfer made from a diseased chinch bug in January, 1910. 
Group.| Inoculated May 26. May 31. June 2. June 6. 
No apparent fun- 
gus growth; 
some bugs still 
living. 
Beginning of 
growth, appar- 
ently Sporotri- 
chum; growth 
first appearing 
on leg; all bugs 
1 | In legs; at least con- 
tact of spores with 
injured surface. 
Majority of bugs 
covered with 
Sporotrichum. 
dead. 
2 | Spores placed on un- | No fungus growth | No fungus growth | Several bugswith 
injured leg. apparent; some apparent; some S porotrichum; 
bugs still living. bugs still living. some still liy- 
| | 
men, 
nn | 
Controls; 
no spores 
added. 
Beginning of fun- 
gus growth; all 
bugs dead. 
Apparently no in- 
fection; some 
bugs living. 
All or nearly all 
covered with 
Sporotrichum. 
Apparently no in- 
fection; some 
bugs living. 
ing. 
Apparently all 
covered with 
Sporotrichum. 
Apparently no in- 
fection; at least 
one bug living. 
ARTIFICIAL INFECTION—FIELD EXPERIMENTS. 
The fungus material used in the following experiments was grown 
in the laboratory by methods already described. In the field the 
dried petri-dish cultures were rubbed up with dry earth, making a 
mixture that was light-colored, due to the large admixture of spores. 
The mixture was dusted directly on the bugs on the infested wheat 
or corn, and on the ground at the base of wheat, where the insects 
congregated. 
Shading experiments.—To test the effect of shade, artificially pro- 
duced, on Sporotrichum in its parasitic relation to chinch bugs, small 
