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

          PROPHYLACTIC ACTION OF " BAYER 205 " AGAINST EXPERIMENTAL
                                TRYPANOSOMIASIS IN ANIMALS.

Perhaps the earliest published records of experimental observations upon the
prophylactic action of "Bayer 205" are those of Mayer and Zeiss [1921], who,
experimenting upon mice, found that the drug remained for several months in the

animal body and during this period it served as a prophylactic against infections
due to T. brucei, T. gambiense, T. equiperdum and T. equinum.

Pfeiler [1922], working with T. equiperdum, found that " Bayer 205 " conferred
protection on small animals which lasted for periods up to 200 days.

Ruppert [1923] found that a dose of 0.4 gramme per kilo. body weight pro-
tected rabbits, for periods up to 6 months, against infections due to T. brucei, T.
equipendum and T. equinum. He also injected 8 horses with increasing doses of
the drug, 3 with 0.25, 2 with 0.5 and 3 with 0.75 gramme per hundredweight
(" pro zentner "), the animals being inoculated with T. equinum after varying
intervals. It was found that a dose of 0.5 gramme was effective for one month,
but that in animals that had received 0.25 gramme, the infection was succesfully
produced after 14 days.

Hesselbach [1922] published the results of a rather remarkable series of ex-
periments upon the prophylactic action of " Bayer 205" against experimental
infection of guinea-pigs with T. equiperdum. Four equal-sized guinea-pigs were
each given a subcutaneous injection of 0.04 gramme of " Bayer 205 " and infected
intraperitoneally with the trypanosomes, 1, 3, 6 and 10 days after the prophylactic
inoculation. None of these animals developed the disease. Hesselbach's findings
are of special interest in that he made laborious observations upon the morpholo-
gical changes undergone by the parasites from hour to hour following upon the
injection of the drug, and for this purpose the trypanosomes that had been injected
into the abdominal cavity (" die in die Bauchhöle gespritzten ") were lifted out
again ("wieder herausgehebert ") by means of a capillary pipette and examined
both in fresh and dry preparations.

Brumpt and Lavier [1923], working with T. equinum, failed to produce the
disease in mice that had been given 5 mg. of " Bayer 205 " 78 days previously.

Schmidt and Oliveira [1924] failed to infect small animals with Mal de Caderas
within a month of the protective inoculation with " Bayer 205 ". These workers
also observed the prophylactic effect of the drug against the same infection in a
mule and a mare which were given 2 and 3 grammes of the drug res-
pectively a fortnight and 6 weeks before inoculation with 10 c.c. of the infective
blood. Neither of these animals developed the infection.