315 
A CONTRIBUTION TO THE BIOLOGY OF 
TRYPANOSOMA EQUIPERDUM. 
By E. TWANOW, 
Director of the Central Experimental Station for the Breeding 
of Domestic Animals , Moscow. 
It has hitherto been firmly established from experience gained in the stud- 
farms and by experimental investigations (Hertwig, Prince and Lafosse, 
Frasbot, Pench) that Dourine is transmitted almost exclusively through 
coitus. Flies take no part in the transmission of the disease (Laveran and 
Mesnil), however, the possibility of infection through the bite of fleas (Rabino- 
witsch and Kempner) or ticks, is not excluded, and was proved experimentally 
(Sieber and Gonder). Experiments conducted on rabbits and dogs (Rouget, 
Schneider and Buflard, Laveran and Mesnil) have shown that T. equiperdum is 
capable of penetrating through the intact mucous membrane of the eye and 
genital organs, but not through the alimentary tract. Manteuffel’s experiments 
have shown that T. equiperdum can even penetrate through the intact skin. 
It should be noted, however, that infection does not necessarily take place 
in all cases of coitus with known infected animals. According to Nocard and 
Leclainche, an infected stallion infects on the average two-thirds or three- 
quarters of the mates covered by him, i.e. one-third or one-quarter of the 
latter remain healthy in spite of coitus with an infected stallion. 
Since in nature Dourine is transmitted only through coitus and since 
T. equiperdum is capable of penetrating through intact mucous membranes, 
it was naturally assumed that the infection is introduced together with the 
sperm into the vagina, whence it passes through the mucous membrane into 
the blood. The fact that T. equiperdum was found in the testis of an infected 
animal (Rouget), seemed to support this view. The infection of the male from 
the female also found explanation in the capability of the trypanosome to 
penetrate through intact membranes. 
Having worked on the disinfection of the sperm and conducted a series of 
observations on coitus in animals, I found it necessary to verify the facts 
mentioned above. My object was to find whether T. equiperdum passed into 
the sperm, and, if it passed, whether it was capable of penetrating through 
the intact mucous membrane of the female genital tract. For these experi¬ 
ments I used mice, rabbits and dogs. 
I found that in mice the contents of the accessory genital glands ( vesicula 
seminalis) remained free of T. equiperdum, at the time when these parasites 
were abundant in the blood. 
