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several cover-glass specimens of it were examined every day. Consequently two more Guinea Pigs were
inoculated. These were distinguished as No. III and No. IV and each received 0.2 c.c. of blood from
the bull on the 163rd day after its inoculation. Nos. III and IV Guinea Pigs both developed hæmatozoa
on the 10th day, and the organisms remained almost constantly present in their blood until the day of
the death, 24th October and 14th December respectively.
On the 13th November 1891, that is, 234 days after the inoculation of the bull, two Guinea Pigs Nos.
V and VI were inoculated with 0.2 c.c. of blood from that animal, but as no hæmatozoa, were found
during the next 32 days, they were re-inoculated on the 16th December 1891, 267 days after the inocu-
lation of the bull, but with negative results a second time. Between the latter date, 16th December
1891 and March 14th, 1892, the bull appeared to be enjoying good health and putting on flesh. On
this latter date, that is, 356 days from the time of inoculation, two new Guinea Pigs Nos. VII and VIII
were inoculated as previously with 0.2 c.c. of blood from the bull, but this experiment was also
followed by negative results. Since 24th March the bull has been in very fine condition, and as it is
desirable to ascertain whether animals of the bovine species are liable to a second attack of Surra, it was
resolved to re-inoculate this animal with a more virulent type of Surra, obtained by passing the hæma-
tozoon of the rat (Mus decumanus) through the horse and donkey. This second inoculation was per-
formed on 22nd August 1892, when 1.0 c.c. of blood drawn from the jugular vein of the donkey
was subcutaneously injected over the left scapular region, the blood at the time containing very numerous
and active hæmatozoa. No swelling and œdema followed, only slight subcutaneous thickening in the
tract of the injection needle. On the 8th of the same month, a peculiar organism was found in the
blood, but on that day only. The animal put on flesh and appeared in robust health. On 21st Sep-
tember 1892 two Guinea pigs were inoculated with blood drawn from the jugular vein, but up to the
14th November 1892 their blood, which had been examined daily, failed to show any signs of the Surra
hæmatozoon.*
The blood of Bull No. I was submitted to microscopical examination until the 22nd July 1893, a
period of 345 days after the date of the second inoculation. No Surra hæmatozoa were observed, but
only one giant form of Trypanosoma on 27th August 1892.
The chief points of interest amongst others in this case are that—
1. This is the first recorded case of any of the bovine species having been successfully inoculated
with the hæmatozoon of Surra.
2. The animal should have entirely thrown off the disease, and again become strong and in good
condition, is worthy of notice and may prove important in the future treatment of the disease
especially when we recall the absolute fatality observed amongst horses afflicted with this
malady.
3. After re-inoculation with a more virulent form of material, primarily derived from the rat
(Mus decumanus), no local manifestations should occur at the seat of the injection of blood, or
symptoms of the disease follow.
4. The loss of virulence on introduction of the hæmatozoon into the bovine species points to the
fact that there may be a possibility of producing some form of immunity in other species of
animals by the introduction subcutaneously or by intravenous injection of the blood, serum,
or proteid matter from the blood of bovines, some time after their inoculation or re-inocula-
tion on numerous occasions with Surra.
Bull No. III, aged 4 years. This animal was subcutaneously inoculated on the 31st July 1891
with 1.0 c.c. of blood containing very numerous hæmatozoa taken from the jugular vein of Horse No.
LXVII, previously passed through the horse from the rat (Mus decumanus). A considerable amount
of swelling and œdema with tenderness on manipulation followed at the seat of the injection. The
latent period occupied three days. The hæmatozoon was present in the blood from the 3rd to the 9th
August inclusive. After an interval of thirteen days it was again present in small numbers for two
days, August 23rd and 24th, after a second interval of nine days it re-appeared for one day on the 3rd
September. During a further period of 158 days accompanied by daily microscopical examinations of
the blood, no organisms were observed. The temperature became rapidly elevated after inoculation and
attained a maximum of 41.4° C. on the 4th day of the disease, and then gradually fell until the morning
of the eighth day when it registered 38.8° C. It again rose to 41° C. on the 37th day. The pyrexia
since November 14th has been characterized by morning remissions and evening exacerbations espe-
cially on the 143rd, 155th, 156th, 168th and 178th days of the disease. During the months of August
and September this animal became greatly emaciated, but by December had put in a considerable
amount of flesh and appeared quite healthy.
On the 3rd September 1892, the 191st day after inoculation and the 158th since the last appear-
ance of the organism in the blood, it was decided to re-inoculate the animal with Horse Surra blood in
order to test whether any protection had been acquired from the previous inoculation. Consequently
on February 9th, 1893, the animal was re-inoculated subcutaneously with 2.0 c.c. of blood drawn
from the jugular vein of Horse No. LXXXIV immediately after death, but which just before death
contained numerous hæmatozoa.
* Two Guinea-pigs inoculated on the 21st September 1892 with 0.3 c.c. of blood in which no hæmatozoa could be discovered
microscopically, contracted Surra after a latent period of 14 days.