1918] Glaser—On the Existence of Immunity Principles in Insects 45 
Experiments. 
(1) 2 drops! 9 femur-rubrwm immune blood + 1 c.c. bouillon + 1 loop of B. poncei. 
(2) 2 drops 9 femur-rubrum immune blood + 1 ¢c.c. bouillon + 1 loop of B. ponceit. 
(3) 2 drops o& femur-rubrum immune blood + 1 c.c. bouillon + 1 loop of B. poncet. 
Checks. 
drops bouillon + 1 ¢.c. bouillon + 1 loop of B. poncei. 
drops 2 femur-rubrum normal blood + 1 c.c. bouillon + 1 loop of B. poncet. 
drops o femur-rubrum normal blood + 1 ¢.c. bouillon + 1 loop of B. poncez. 
(1) 
(2) 
(3) 
The six test tubes were incubated for 24 hours at 35° C. At the 
end of that period neutral potato agar plates were poured from the 
six cultures using the customary one, two, and three dilution 
method. Each experiment and each check was represented by 
three plates making eighteen plates altogether. They were in- 
cubated for three days at 35° C. after which a count was made of 
the developed colonies. The colonies on the six first dilution 
plates (experiments and checks) were too numerous and confluent 
for counting. Those on the six second dilution plates were also 
extremely numerous. At a glance one could tell that the colonies 
on the check plates were more numerous than on the experimental 
plates. By taking counts of sections of all the plates I arrived at 
the conclusion that the ratio of check to experimental colonies was 
about 10: 1. 
With the six third dilution plates I was able to make actual 
colony counts for the three experiments and three checks. 
to to bo 
NUMBER OF COLONIES ON THIRD DILUTION PLATEs. 
Checks. Experiments. 
ayes 0 
ay 4 0 
(syne 0 
As can be seen from the foregoing table Checks 1, 2, and 3 gave 
7, 4, and 6 colonies respectively, whereas nothing at all was ob- 
tained on the three third dilution experimental plates. 
These experiments taken in conjunction with the other results 
I have presented show that it is possible to bring about the forma- 
tion of bacteriacidal properties in some insects. From my tissue 
culture work discussed under phagocytosis, I have shown that 
normal insect blood is somewhat antagonistic towards bacteria, 
1 Two drops equals !/s of a cubic centimeter. This is the maximum amount of blood which 
one can obtain from one animal at a time. 
