E. Hindle 
145 
Infectivity of eggs. 
The infectivity of a certain proportion of the eggs laid by an 
infected parent is proved by the fact that a varying percentage of 
the nymphs, which hatch out from them, are capable of producing 
infection when they feed on a healthy animal. Three experiments, 
however, were performed by injecting the contents of eggs into mice. 
In each case the parent and the eggs had been kept at a uniform 
temperature of 21° C. and in none of them were spirochaetes detected 
by microscopical examination k 
Exp. 1. Mouse, injected with the contents of 12 eggs, laid by an 
0. mouhata fed on an infected mouse 20 days previously, and kept at a 
uniform temperature of 21° C. Result—negative. 
Exp. 2. Mouse, injected with the contents of 12 eggs, laid by an 
0. mouhata fed on infected mouse five weeks previously, and kept at a 
uniform temperature of 21° C. Result—positive, the mouse becoming 
infected after four days incubation period. 
Exp. 3. Mouse, injected with the contents of 10 eggs, laid by an 
0. mouhata fed on infected mouse five months previously, and kept at a 
uniform temperature of 21 °C. Result—positive, the mouse being in¬ 
fected after seven days incubation period. 
These results are sufficient to show that the infected eggs are 
capable of producing an infection when injected into mice, even though 
they have been kept at a moderate temperature (21° C.) and do not 
contain recognizable spirochaetes. 
Coxal fluid. 
In three cases the coxal fluid was carefully collected from infected 
ticks, whilst they were feeding, and injected into mice. The results 
were negative in each case, and therefore it is probable that the coxal 
fluid does not contain any infective material. It plays an important 
part, however, in the production of infection when the tick feeds, as by 
means of this fluid, which bathes the under surface of the tick, the 
infective material contained in the excrement is carried into the wound 
caused by the tick’s bite. 
^ In every case we only give the results of microscopical examination for typical 
spirochaetes. Other forms of th'e parasite will be considered later. 
