8
the control. Others showed no thermal reactions, a sign that the dose of
serum injected was too large and therefore the " causal agent " was destroyed,
without conferring any active immunity. In order to prove this supposition,
the surviving animals were again, after a period of eight days, subjected to a
larger dose of Hæmorrhagic Septicæmia virulent culture, to test their degree
of protection. It was found that the animals which had respectively exhibited
thermal reactions, viz., those which received doses of buffalo testes serum,
yolk of egg products and casinogen survived the ordeal, and. the others suc-
cumbed in various periods, demonstrating the fact that the passive immunity
conferred was but of short duration.
In a second series of experiments with enhanced doses of Hæmorrhagic
Septicæmia culture in the first instance, it was discovered that the serum
prepared from the casinogen (milk) was the only one which stool the severe
test, and in this case the animal exhibited no symptoms other than a slight
thermal reaction, emphasizing the great power of this form of serum which
2 years and 9 months in bottles at the time of retesting still maintained its
efficacy.
Equine Surra.
31. To attenuate by passing through the body of animals.—This question
has been dealt with in a paper already published by me in the Journal of
Tropical Veterinary Science, Part I, and the results of further experiments
under investigation will be recorded in due course when they are concluded.
32. By the administration of certain chemicals.—The series of experiments
commenced during last year which had for their object the cure of Eqaine
Surra by the administration of arsenic and trypan-rot were continued during
the last 12 months.
Of five country-bred ponies, the subjects of Equine Surra, two recovered
after treatment with arsenic and trypan-rot. One of these animals had
presented numerous to swarming trypanosomata in the blood for 19 conse-
cutive days, previous to the commencement of the intravenous injection
of the chemicals in combination, and a successful termination to the case was
not anticipated. Death followed in the unsuccessful cases in 130, 134 and 191
days respectively after the commencement of the treatment.
Aged Australian horses, the subjects of Equine Surra, treated by the
above methods, with doses according to their body weight, succumbed in 36
and 38 days; the flagellates being absent from the peripheral blood for periods
of but 20 and 30 days respectively. It has been observed that the best time
to inject arsenic and trypan-rot intravenously is not when the trypanosoma
is present in large numbers in the peripheral blood of the animal, for then the
toxin present in varying quantities appears to combine with the chemicals
introduced and together they produce rapidly fatal results. It has been
demonstrated by practical experience that the best effects are produced when
arsenic in combination with trypan-rot are introduced intravenously on
the first day of a paroxysm of Surra, when the toxin has been in whole or in
part eliminated from the system of the animal, and this has allowed of the
flagellate reappearing in small numbers in the blood of the peripheral circula-
tion.
33. To attenuate the trypanosoma by means of cultures.—These experi-
ments have been largely augmented during the past year, full advantage
having been taken of all the new and improved media worked out by other
observers in various parts of the world, but especially those put forward by
Messrs. Novy and MacNeal, the originators of this line of research. Our
experiments have not been as successful as could be desired, but when we
compare the results which MacNeal has recorded together with his failures,
we have no cause to lose heart at our results, for, the above-mentioned
investigators recorded " fifty independent series of cultures trials had to be
made by them before they could duplicate the last positive results."
34. Surra in deer.—With a view to determine whether black buck are
capable of conveying the T. Evansi in their blood for long periods as in the
case of bovines and thus being able by the aid of flies to disseminate the
disease to other susceptible animals, three black buck were respectively
inoculated with Varying amounts of blood taken from control Surra Equines ;