26 
TryiKmosoma gambiense 
is given to the rats, there will be a more copious secretion of gastric 
juice and also fewer parasites introduced, than when blood is injected 
into the mouth, and consequently ther'e will be a greater chance of 
the trypanosomes being overcome before they have been able to 
peneti’ate the wall of the alimentary canal. It was found by experiment 
that trypanosomes when mixed with gastric juice soon become non- 
motile, and the rapidity with which this takes place depends upon the 
relative proportions of the trypanosome-containing blood and the 
gastric juice. 
{h) Infection per vaginani. A few experiments were made to 
ascertain whether T. gambiense can be transmitted from rat to rat by 
coitus, but although infected males were kept with healthy females and 
vice-versa, up to the present we have not obtained any infection by these 
means. In addition a number of female rats were isolated and into the 
vagina of each a drop of infected blood was introduced by means of a 
small and carefully rounded glass tube, great care being taken to avoid 
the possibility of producing any abrasions. After incubation periods 
varying from 5—8 days all the rats became infected and the disease 
followed its normal course. This experiment has been repeated six 
times, in every case with positive results. 
(c) Infection per cutaneam. The following experiment was carried 
out to ascertain if T. garrihiense could pass through an undamaged 
epithelium. A drop of infected blood was spread over some part of 
the body of a rat, whose hair had neither been shaved nor cut, and 
allowed to dry. After about one hour the dried blood was covered with 
a layer of collodion, and the rat then set free. After a normal incubation 
period three (two males and one female) out of five rats thus treated 
became infected. On repeating these experiments with rats that had 
been shaved success was invariable, but in the operation of shaving 
there is always the possibility of producing small abrasions. 
The foregoing experiments clearly show that in rats T. gambiense is 
able to penetrate a sound mucous membrane and also an undamaged 
skin and there is no reason to suspect that this parasite would not 
possess similar powers in its normal host, man. Moreover, the ease with 
which it passes through the mucous membraiie of the vagina, shows that 
there is every possibility of Sleeping Sickness being transmitted by 
coitus. 
Although there is no direct evidence to show that trypanosomes 
ever occur in the seminal fluid, yet in the case of dourine {T. equi- 
jjerduni.) transmission normally takes place by coitus and it is necessary 
