136 Transmission of S. diittoni 
were allowed to gorge. The fact of their all having bitten the first 
monkey was verified by observing the punctures and small ecchymoses 
which surrounded the bites. As is well known, when these ticks 
commence to swell they pass a large quantity of clear fluid from the 
coxal glands (whose anti-coagulating properties I have been able to 
determine) and some, in addition, pass the white secretion of their 
Malpighian tubes. These fluids, therefore, bathe the skin of the 
monkey and almost certainly may penetrate into the subcutaneous 
tissues through the punctures left when the tick has loosened its hold 
on its host. The two monkeys, then, although bitten by the same ticks, 
differed in the following respect: on the first none of this fluid had 
been passed, while on the other the wounds were bathed in it. Some 
of the fluid passed on the second monkey was also collected and 
inoculated hypodermically into a mouse. Careful search of this fluid 
showed neither spirochaetes nor granules; the latter, however, are so 
minute that they might readily be missed. The result of this experi¬ 
ment was interesting and suggestive ; the first monkey was not infected, 
while the second monkey and also the mouse developed tick fever, 
which ran a typical course” {Lancet, 1910, p. 13). 
In addition a few experiments were performed by isolating the 
tissues and organs of infected ticks and, after emulsification in saline, 
injecting the material into white mice. The results were negative in 
the case of emulsions made from the Malpighian tubes and salivary 
glands of two ticks known to have been infected and kept at a uniform 
temperature of 24° C., and also in the case of an injection of the salivary 
glands of a tick that had been kept at a temperature of 37° C. for two 
days before the operation. The only positive results were obtained 
from the emulsions, respectively, of the gut-wall, Malpighian tubules, 
Malpighian secretion and ovary, of a tick that had been kept at ^ 
temperature of 37° C. for two days before dissection. 
Leishman’s important observations on the morphological changes 
taking place in the spirochaetes after entering the tick will be con¬ 
sidered in a later communication, dealing with the morphology of 
(S', duttoni. 
Schuberg and Manteufel (1910) have recently discovered that certain 
individuals of 0. moubata may acquire an active immunity against in¬ 
fection with S. duttoni, and also S. I'ecurrentis. About 100 young ticks 
were infected, half with East African Relapsing Fever and the other 
half witli Russian Relapsing Fever, and afterwards kept at a uniform 
