PROPHYLAXIS AGAINST EQUINE SURRA                          293

manner with the dose, each increase of 0.0901 gramme increasing the period of
resistance by about 5 days, although with large doses the progression was not so
regular.

Reference has already been made to the observations of Berg [1925 ] pointing
to the fact that "Bayer 205 ", when used alone, is valueless as a prophylactic agent
against T congolense infection. Berg, however, records having obtained satisfactory
results from the combined use of " Bayer 205 " and tartar emetic when tested upon
cattle exposed to natural infection in fly belts in South Africa. The animals were
injected in doses ranging from 2.5 to 10 grammes of " Bayer 205 " and with 1 to
1.5 grammes of tartar emetic, the two drugs being mixed and injected mainly
("in der Hauptsache")by the intravenous route. Perhaps it would be useful to
indicate here the actual method of preparing the two drugs for injection. One
gramme of tartar emetic is added to 40 c. c. of water in a clean flask, and at the
same time, the appropriate quantity of " Bayer 205 " is weighed and kept apart.
The mouth of the flask is closed with a piece of linen or wadding and the flask is
now placed in a vessel of cold water which is brought to the boil over fire. When
the mixture has been thus sterilized' for ½ hour, the flask is removed from the
jacket of water, the contents cooled to 60° C. and the previously weighed quantity
of " Bayer 205 " added to the solution. The results obtained from the prophylactic
use of the two drugs singly and in combination were as follows :—Out of 18 animals
injected with "Bayer 205" alone, 6 (or 33.5 per cent.) escaped infection; 13
animals received the combined injection, and of these 9 (or 69 per cent.) escaped
infection; of 3 animals treated with tartar emetic alone, 1 (or 33.5 per cent.) was
protected. 16 animals were used as controls, and all of these became infected. It
would, however, seem difficult to find any a priori explanation for the superiority
of the combined drugs over " Bayer 205 " alone, although, as suggested by Collier
[ 1926 ], it is possible that a " globulin Bayer" compound is formed when " Bayer
205 " is introduced into the circulating blood and that this compound is changed
by the addition of antimony. The method of treating with the combined drugs
would seem to merit trial under field conditions in India, since, if a combination
of the two drugs proves to be really superior to " Bayer 205 " alone, then the
former should doubtless be preferred in view of the rather prohibitive cost of
"Bayer 205".

                                                        REFERENCES.

Allen (1930). Observations on an Outbreak of Equine Surra with special Reference to Vectors,
and Means for Control. Vet. Journ., 86, 51-63.

Bakker (1925). Notes on Surra in Padang Sidempoean. Ned. Ind. Bladen V. Diergeneesk en
Dierenteelt, 37, 153-177. (Abstr. in Trop. Vet. Bull, 13, 76-78 ; 1925.)

                                                                                                        D 2