26
(ii) The amount of swelling and œdema which followed inoculation, at and around
the seat of the injection, finally disappeared on the 14th day after the operation ;
also the temperature 41.°C. (103.8°F.) registered on the morning of the 8th
day.
(iii) The protracted period of incubation of the disease, whether we take it as terminat-
ing on the first appearance of the urticarial eruption on the 44th day as pre-
vious experience points to the Hæmatozoon being the cause of the manifestation
in the skin or on the 75 th day when the organism was found for the first time
in the blood. In either case the length of the latent period 63 days, has only
once been exceeded, viz.—in Horse LXII which was inoculated with soiled rat's
blood.
(iv) The discovery of the 'Trypanosoma' in the blood on the 76th day after inocula-
tion, when a long and active specimen of the organism was alone observed; the
dorsal membrane in which was particularly well developed. The absence of
further specimens from the blood, during a prolonged period of 121 days.
(v) The marked evening exacerbations and morning remissions of temperature which
occurred on the 55th, 56th and 59th days of the disease.
(vi) The loss of flesh during the months which immediately followed inoculation.
(vii) Re-inoculation of the animal with Horse Surra 197 days after the former injection
of soiled rat's blood, followed by high fever, but a total absence of swelling
at the seat of inoculation.
(viii) The appearance of the Surra organism in the blood for a period of 48 hours, 80
days later, and re-appearance for 24 hours on the 158th day, but total absence
during a further period of 195 days.
Cow.—The experiment determined upon, had for its objects :-—
(i) If Surra is communicated to a cow in milk sub-cutaneously, does the Hæmatozoon
or its immature form pass from the general circulation into the milk ?
(ii) Will a calf suckling its mother, under such conditions, contract the disease ?
A cow with a calf three weeks old at her side, contracted Surra.* The blood of the
mother was found to contain the Hæmatozoon for a period of 120 hours. The calf was allowed
to suckle three times in the twenty-four hours, and the milk from each teat was daily examined
microscopically for the presence of the organism; but this was never discovered. On the
38th day from the appearance of the Hæmatozoon in the circulation of the mother, it appeared
in the blood of the offspring, which up to that date had been free. The organism remained
in the circulation for 24 hours only, and had not re-appeared 123 days later.
Blood in small quantities must have become mixed with the milk, owing to rupture of
some small mammary vessels, and by this means the Hæmatozoon entered the digestive tract
of the calf.
On February 9th, 1893, the calf having grown considerably and being in good condition
it was decided to re-inoculate it, with a view to ascertain whether the animal had received any
protection from the presence of the 'Trypanosoma' in its circulation. Consequently the same
evening the calf received sub-cutaneously 1.0 c.cm. of blood taken from the jugular vein
of Horse No. LXXXIV immediately after death. No local manifestation followed at
the seat of the injection. The latent period occupied a little over three days, the Hæmatozoon
being present for two days, February 13th and 14th, and again for one day (18th) after an
intermission lasting 72 hours. From the 18th February, until September 30th, 1893, a period
of 224 days, the organism was present in the blood once and then only for a few hours,
viz., on the 22nd June, 123 days after its last appearance.
The animal contracted rinderpest, the first symptom appearing on the 28th, and
succumbed to that disease on the 30th September 1893.
A similar experiment with the same end in view as in the case of its offspring was
initiated in the cow. It was re-inoculated on the 9th February 1893, with 2.0 c.cm. of blood
containing numerous Hæmatozoa taken from the jugular vein of Horse No. LXXXIV
immediately after death. The latent period occupied 8½ days, no local manifestations being
observed at the seat of the injection. From the first appearance of the organisms in the
blood on the 18th February 1893, until 31st May 1894, six paroxysms each lasting 1 or 2
days occurred, the Hæmatozoon never exceeding two in a field of the microscope. The length
of the intermissions were, 10, 29, 70, 9, 128 days; but as the examination of the blood was
discontinued on May 31st, 1894, 214 days since the last appearance of the organism in the
blood, it is very unlikely that the Hæmatozoon would have again appeared in the circulation.
On this latter date, the animal was in good health and in very fair condition.
Hissar Bullocks at Karnal.-—In two cases of spontaneous Surra in bovines (Hissar
bullocks) observed at Karnal during the months of December 1895 and January 1896, the
animals had been ailing for some four months but thin and emaciated during the eight weeks
prior to my visit. In both these cases the attack of Surra was complicated by the presence
* During the latent period, there was no swelling or œdema observed at the seat of the injection of blood,
although a slight thickening would be felt in the sub-cutaneous tissue.