119
days. The temperature varied between 37.2°C. and 40.4°C. A second invasion of the eruption occurred
between the 34th and 44th day of the disease. At first the rash was confined to the thighs, but later
appeared over the whole body. The animal had been subjected to treatment with Arsenic, and the
first appearance of the second attack coincided with the first day of the second paroxysm. For the
first two days the temperature was high, 40.2°C., but for the last eight, the thermometer recorded a
maximum of 37.6°C. A third attack of urticaria was noticed on the 82nd and 83rd days of the disease.
On this occasion the eruption selected the chest, fore-limbs and thighs, and the temperature remained
very low, viz., 36.2°C., maximum 37.4°C. A fourth time the rash made its appearance on the 99th and
100th day of the disease, two days before a paroxysm, but it faded immediately the hæmatozoon made
its appearance in the blood. The temperature varied between 38.2° and 39.4°C.
We found that the urticarial eruption in the two naturally acquired cases of Horse Surra previously
reported occurred on the first day of the disease, and was of the form known as ' urticaria evanida.' In
the experimental cases of the same disease the conclusion arrived at was that the rash might show
itself any time from 18 hours after inoculation until the 22nd day after the appearance of the organism
in the blood. In the observations conducted with the rat trypanosoma we find that in the three
animals, two of which Nos. LXII and IX contracted the disease by the subcutaneous inoculation of
soiled blood, in the former the eruption appeared concurrently with the hæmatozoon on the first day of
the disease, and in the latter on the 3rd day of the disease. In horse No. XCI, fed on rat excrement
mixed with the ration of corn, the urticarial eruption was the first symptom which drew attention to
the animal's condition; on this occasion it persisted for eight days, but returned for a period of ten days
between the 34th and 44th days and again for 48 hours on the 82nd and 83rd days and yet again on
the 99th and 100th days of the disease.
In both horses LVIII and LXIX the eruption remained visible for 12 hours in each case, on the
second day of the disease, and in horse XIII it broke out on the fourth day for 12 hours, and again
remained patent for 72 hours between the 15th and 18th days of disease. Out of the first 55 cases of
Horse Surra under observation the urticarial eruption appeared in 12 or 21.81 per cent, while in the 19
cases now recorded in equines, directly or indirectly derived from the rat, it showed itself in 6 or
31.58 per cent.
Swelling and œdema at the seat of inoculation in experimental cases:—When an , animal has been
inoculated subcutaneously with the soiled Surra blood, collected either during a paroxysm, intermission
or after several hours post-mortem, a considerable swelling as a general rule follows at the seat of
inoculation. This tumour tends to increase in size for a varying number of days, becoming more tense
and tender on manipulation; then, somewhat suddenly, is found, on examination, to have become soft
and flaccid, so that little or no notice is taken by the animal if the tumour is pressed with the hand.
If the blood be now examined microscopically, the hæmatozoon in animals inoculated with Horse Surra
blood will be found to present the organism. The 'trypanosoma' is localized in the tumour, until it
leaves the swelling and becomes generalized through the circulation. In the previous results published
with regard to Horse Surra, it was stated that " in one case only out of 22 which contracted the disease
by experimental means, was the swelling absent from the seat of inoculation ; but in this, from first to
last, during a period of nine days, no swelling or thickening of the integument could be felt. The
shortest time noted in horses during which the swelling attained its maximum and commenced to
decrease in size, was 96 hours, and the longest 12 days, the average length of 21 cases being 6.7 days.
Within a very few days after the appearance of the hæmatozoon in the blood, the tumour has usually
decreased considerably in size, and after a fortnight, only a slight thickening of the skin can be noticed
on careful examination."
Considerable variation in the results obtained has been observed in experimental horses sub-
cutaneously injected with rat's blood, containing the 'trypanosoma,' as will be seen in the following short
notes of the animals submitted, under their respective headings.
SUBCUTANEOUSLY INOCULATED WITH SOILED RAT'S BLOOD.
Positive cases.
Horse No. IX.— Received 1.0 c.c. rat's blood, hæmatozoa numerous, in left scapular region.
Swelling appeared on the following day, reached a maximum on the 12th day after inoculation, remained
stationary, with regard to size and tension, until appearance of the hæmatozoon in the blood on the
19th day. The swelling then lost its tension and tenderness, and within a few days all signs of the
tumour had disappeared.
Horse No. XX VIII.—Received 0.75 c.c. rat's blood in the shoulder and the side of the head. The
former swelling had disappeared by the 10th day, whereas the latter only attained a maximum on the
15th day, but had disappeared by the next morning. The hæmatozoon did not appear in the circulation
of the animal until 29 days after inoculation or 14 days after the subsidence of the local manifestations.
Horse No. XLII.—This
animal received 1.0 c.c. rat's blood, hæmatozoa numerous, in the shoulder
and in the neck. In both instances the swelling attained its maximum on the 13th, and the hæmato-
zoon appeared in the blood on the following day. Reduction in the size of the swelling then rapidly
took place.
Horse No. LXII.—Subcutaneous
injection of 2.0 c.c. rat's blood, organisms very numerous, on
left scapular region. Maximum swelling 10th day, reduction commenced 11th day, total disappear-