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THE CURE OF SURRA IN HORSES BY THE 
ADMINISTRATION OF ARSENIC. 
By J. D. E. HOLMES, M.A., D.Sc. 
Imperial Bacteriologist to the Government of India. 
(With Plates XXII to XXYII.) 
In a previous paper which appeared in Parasitology, Vol. in. 
pp. 73—107, and the Journal of Tropical Veterinary Science, Yol. ir. 
No. I, details were given of thirty-two cases of successful treatment of 
Surra in horses by means of arsenic and its derivatives. 
The object of the present article is to report on the progress of 
these cases under a prolonged period of observation, and to describe 
further experiments which have been carried out, on the same lines of 
treatment, in the Muktesar Laboratory. 
Both results further confirm the conclusion, previously arrived at, 
that the treatment effects a complete cure of Surra, and not merely 
establishes a temporary tolerance of the disease. In the former publi¬ 
cation, a tabulated list was given of Surra animals which had shown no 
return of the disease after treatment, together with the periods during 
which they had been kept under daily observation ( Parasitology , 
Vol. hi. p. 103). 
These periods were dated up to September 30th, 1909. Since 
that date these animals have been at woi’k, and their blood has 
been examined at intervals of two and three weeks. 
The last examination was made on Jan. 31st, 1910, at which time 
all were in good condition, and no trypanosomes could be detected in 
their blood. During this period of four months (Oct. 1909 to Jan. 1910) 
a number of dogs, rabbits and guinea-pigs were inoculated with blood 
from these animals. All gave negative results. In February 1910 I 
left India, on furlough, but arranged that a number of these Surra 
recovered ponies will be available for examination on my return, at 
the end of the present year. 
