8
numerous trypanosomata. Period of incubation 8.5 days. Twenty paroxysms
lasting 79 days and twenty intermissions lasting 444 days followed, making
a total of 523 days. On the 4th August 1906, the animal not having exhibited
any trypanosomata in its blood, for several months, was tested with sponta-
neous equine trypanosomiasis, receiving 1.0 c.c. of blood subcutaneously
(flagellates numerous). Period of incubation 6.5 days. Six paroxysms and
six intermissions occurred, lasting 28 and 38 days, respectively. The animal,
succumbed on 15th October 1906, 605 days after the primary and 73 days
after the secondary inoculation.
From the results obtained from the above experiments, it will be observed
that animals (camel and donkeys) which have acquired immunity for the
casual factor of camel trypanosomiasis are still susceptible and succumb to the
T. evansi.
29. Hæmorrhagic Septicæmia.—After having been passed through a
succession of rabbits, the lethal dose for bovines of the organism of the disease
in bouillon cultures, kept for 48 hours at 37°C., injected subcutaneously, was
found to be as follows :—
Plains bulls of 280 to 300 lbs. body-weight, succumbed to a dose of
0.025 c.c. of bouillon culture when made up to 0.5 c.c. with saline solution,
after a period of 93½ hours had elapsed.
Hill bulls of 180 lbs. body-weight, succumbed to a dose of 0.02 c.c.
bouillon culture made up to 0.5 c.c. with saline solution after an interval of
about 95 hours, but when the dose of culture injected was increased to
0.025 c.c., death took place in 47 hours.
When plains animals primarily immunized against Hæmorrhagic Sep-
ticæmia, were later hyperimmunized by the intravenous injection of succes-
sive doses of bouillon cultures, up to a maximum of 12.5, 25 and 35 c.c., respec-
tively, the resultant sera were found to differ somewhat in protective power.
The serum possessing the greatest potency was that obtained from the animals
injected intravenously with 12.5 c.c. of the culture.
A quarter of a cubic centimetre (0.25 c.c.) of this latter serum was found
to be capable of protecting a plains animal, body-weight 320 lbs., when a dose
of 0.033 c.c. of virluent culture, was injected 48 hours after the subcutaneous in-
jection of serum. Whereas a dose of 0.5 c.c. was found necessary to bring about
a similar result when the 25 c.c. and 35 c.c. sera, were respectively tested.
The results of these experiments demonstrate that, instead of much time
and attention being expended upon hyperimmunizing animals through a
number of months, until 35 c. c. of the virulent cultures have been utilized,
a serum of higher protective power may be obtained when a final dose of
12.5 c. c. has been intravenously injected.
Further, that a dose of 1 c. c. of such serum, four times the quantity
used in the experiments for plains animals of 320 lbs. body-weight, should be
sufficient to confer a passive protection for a period of several weeks, ample
time for an outbreak of Hæmorrhagic Septicæmia to die out. For, the pecu-
liarity of this form of malady is that outbreaks follow upon heavy rain, but
they seldom or ever persist in one locality for a longer period than ten days.
30. Charbon Symptomatique.—Two forms of vaccines and an anti-serum
have been prepared during the past official year. Up to the present, no
returns have been received from the various Superintendents to whom the
vaccine was supplied for testing in the field.
31. Dourine.—No fresh experiments could be initiated as the disease
appeared to have completely died out and no virulent material was forth-
coming.
The Arab horse treated with Arsenic and Trypanrot in the early part of
1906, has remained in good health and all signs of Dourine have disappeared,
further this animal's blood is non-infective. In the other cases, which have
been under observation, no further symptoms of the malady have been
exhibited.
32. Specimens examined.—During the year under review, 80 specimens
were submitted to the Laboratory for microscopical examination and report.
In the majority of instances the result of examination was reported by
wire, to the person interested with the least possible delay. The specimens
revealed amongst others, the causal agents of Lymphangitis Epizootica and
Trypanosomiasis, Piroplasmosis in cattle, horses, dogs, and Tubercle, etc.