E. Iwanow 317 
was introduced into the vagina by means of a very fine elastic catheter which 
was lubricated with vaseline. The operation was conducted in two series: 
(}) care was taken not to produce any excoriation of the mucous membrane 
(in eight mice and four rabbits), and (2) with the mucous membrane of the 
vagina scratched (so that blood appeared) with a dissecting needle (three mice 
and one rabbit). 
All the mice of the first series without exception remained alive and showed 
no trypanosomes in their blood during two months, whilst all the mice of 
the second series without exception became infected and succumbed after the 
usual period of infection. In the case of the rabbits of the two series the 
blood was tested by re-inoculation in mice. Infection occurred only in the 
rabbit of the second series. 
My investigations were carried out in 1917. The strain of T. equiperdum 
was obtained from the laboratory of Prof. V. L. Yakimov, to whom I wish 
to express my gratitude. The revolution and civil war in Russia prevented 
me from publishing these observations in due time, as most of my notes 
remained in Ascania-Nova which I left in the Autumn of 1917, and where I was 
unable to return. In the autumn of last year, I succeeded in recovering part 
of the protocols of my experiments from Ascania-Nova, but some of my 
papers, which were ready for publication, and preparations, including those 
of T. equiperdum, have perished. 
As my blood-films from infected animals (stained with Giemsa) were not 
available, and I wished to exclude any doubt regarding the type of trypano¬ 
some employed in my experiments, I tried to repeat the experiments. I did 
not, however, succeed in obtaining a strain of T. equiperdum in Russia. I was 
able to repeat my experiments only this year, during my commission abroad, 
thanks to the facilities kindly provided by Prof. Mesnil in his laboratory at 
the Ins tit ut Pasteur. Here I obtained the same results as before. The intro¬ 
duction of T. equiperdum into the vagina of mice (saline and blood) produced 
infection only in the presence of excoriations in the mucous membrane of 
the vagina. 
On June 30th, 1922, T. equiperdum (five drops of blood from the tail of 
a mouse diluted in 1 c.c. of saline) was introduced into the vagina of five mice 
by means of a fine catheter lubricated with vaseline. One of the experimental 
mice proved to be ill with diarrhoea and died on July 4th, the examination 
of its blood being negative for trypanosomes. The remaining mice are still 
| ^ing, a nd have been under observation for more than a month. 
I The question now arises, by what means is the disease transmitted, and 
how do the trypanosomes penetrate into the blood, if they are unable to pene¬ 
trate through the mucous membrane of the vagina, and, finally, how to 
reconcile the results of observations of other authors with those obtained 
by myself. 
In the coitus of animals, especially such as the horse, there is a whole series 
°f mec hanical and physiological conditions, which in themselves are sufficient 
Parasitology xiv 91 • 
