288 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ I, IV

into the field of experimental therapy of trypanosomiasis, so that, hitherto, the
bulk of the work with this drug has been carried out under laboratory conditions,
without the results having been sufficiently tested as to their value in the actual
prevention of the disease under natural conditions.

Of the recorded observations upon the prophylactic action of " Bayer 205 "
against outbreaks of natural trypanosomiasis in animals, the only ones that
would seem to deserve any special mention are those of Bakker [1925], and
Yakimoff and his collaborators [1927], all of whom employed the drug (for-
tunately for workers in India) against natural surra. Bakker's observations,
which were all made in Padang Sidempoean, were on horses, whilst Yakimoff and
his collaborators used the drug against camel trypanosomiasis in the Ural Region,
the parasite concerned being designated by them as Trypanosoma ninae-kohl-
iakimoff, which, however, as the authors themselves remark, probably represents
a race of T. evansi.

Bakker [1925] used the drug intravenously at the rate of 1 gramme in 5 per
cent. solution and altogether he inoculated 321 horses which were divided into
7 batches, each batch consisting of from 26 to 71 animals. In one batch of 51
animals, the inoculation was repeated after a month, but all the other animals
would appear to have received a single injection of the drug. The horses were
from places where cases of surra were actually present at the time the inoculations
were performed, or, at any rate, 10 to 12 days previous to the inoculations. None
of the treated horses developed surra or any other complication (information as to
the post-treatment observation period, however, is not available).

The observations of Yakimoff and his collaborators [1927], although made on
camels, would seem to bear quotation at some length, in view of the many points
of interest which these observations incidentally furnish in regard to the question
of the infectivity of grazing lands and transmission by vectors, both of which
factors, it is needless to say, will have to be given due consideration in order to
obtain the full measure of benefit from any scheme of drug prophylaxis against
equine surra.

From 1923 to 1927, a total of about 11,052 camels were examined in the
Ural Region, and the examination showed that on an average 25 per cent. of
the camels were infected, the infection in some districts being as high as 40 per
cent. Treatment of infected camels failed to prevent the spread of the disease,
and Yakimoff and his collaborators [1927] therefore tested the prophylactic value
of " Bayer 205 ". The test was carried out on four groups of camels. In the
first group of 20 camels, 12 received a subcutaneous injection of 5 grammes
each and the remaining 8 were kept as controls ; in the second group there were 24