CURATIVE TREATMENT OF SURRA IN BOVINES                      219

from Hyderabad-Deccan. As will be seen from what is stated in the following
section, Naganol was also the drug used throughout the experiments described in
the present paper.

Rodenwaldt and Douwes [1922], however, would appear to discredit all
reports of alleged " cures " in buffaloes and in other animals suffering from
chronic surra infections, for according to these authors, such animals frequently
show long remissions during which " the trypanosomes are so scanty in the blood
that they may be undiscoverable ". They refer to the futility of studying the
action of Naganol upon surra in isolated cases and stress the importance of carry-
ing out large-scale experiments before any conclusions can be drawn regarding
the efficacy of this drug for surra in buffaloes.

It would seem that the final conclusion to be arrived at in regard to the pro-
spects of obtaining cures in surra in the bovine subject by means of drug treatment
will have to be based upon the results of a series of large-scale experiments, as sug-
gested by Rodenwaldt and Douwes [ 1922 ], with due regard to the possibility
that a proportion of the reported relapses in the past may have been, in reality,
cases of re-infection contracted through the agency of insect vectors. As will
be seen presently, this possibility was borne in mind when planning the present
investigation.

                        MATERIAL AND METHODS

In the present investigation a total of fifteen animals, comprising six hill
bulls and nine buffaloes, were employed. As will be explained later, two out of
the nine buffaloes had been actually brought under experimentation long before
the trials originating out of the Australian inquiry were commenced, while
two buffaloes died and one buffalo had to be discarded and replaced by
another during the progress of the investigation. Except for these six cases, the
observation period in the case of all others, was about one year and a half.

The experimental animals were housed in two especially-constructed fly-
proof stables (Plate VII, fig. 1) in order to prevent them from contracting a natural
infection through the agency of biting flies. At the entrance, the stables were
provided with double-doors (Plate VII, fig. 2) designed to prevent any possibility
of access of flies while the attendants are entering or leaving the premises. The
windows and the ventilators were covered with wire-netting, while all outlets for
the drainage of urine and stable washings were suitably screened or plugged up.
It is almost needless to emphasize the importance of protective measures of this
kind, for, as Musgrave and Clegg [ 1903 ] have remarked, " to obtain satisfactory
results such a structure is an absolute necessity ".

The strain of T. evansi used in these trials had been repeatedly proved to be
highly virulent on the equine subject and had been maintained for a number of
years in the laboratory by passing through rabbits and guinea-pigs,