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hand, it was taken after the reaction had begun and up to the time it attained its height, the disease was
always produced, but if the temperature was on the decline, it was uncertain whether the disease would be
produced or not. The blood of salted animals, then, during the period of the reaction contains the virus in an
active state. With regard to the question as to whether any modification of the virus was brought about, it
was found that the disease produced was always severe, and never in any degree modified. On the contrary, an
analysis of the figures show that the incubation period, and to a less marked degree the duration of the disease
before death ensued, were shorter in the case of animals which were injected with blood from salted animals
while reacting than in the case of controls injected with the blood of ordinary inoculated rinderpest
animals.
"In some of these cases, the blood was injected directly into a vein, and in these the incubation period was
a day shorter than when the same blood was inoculated suboutaneously into another animal, and the duration
of the disease was also shortened by one day. This point is of some practical importance, as, when a quantity
of virulent blood is wanted urgently for the serum producing inoculations, it can be obtained a day sooner by
inoculating the control animal intravenously instead of subcutaneously.
"The preparation of the protective serum.—The reports of the successful application of the serum method
in South Africa having reached the laboratory just as preparations were being made for the commencement of
the experiments on rinderpest here, it was at once recognised that this method was likely to be more suitable
to the conditions of the disease in India than the former bile ones, and arrangements were at once made for
the preparation of the serum in considerable quantites. Fortunately, too, just at this time the out-buildings
of the laboratory were practically completed, and four salted animals, which had recovered from an attack of
the disease at the time of the experiments made when Professor. Koch visited the laboratory, 18 months
before, were available for the purpose and were inoculated with increasing dose of virulent blood until 1,000
c.c. were given at once, and were then bled for the production of serum and re-inoculated again with still larger
doses in accordance with the details described by Turner and Kolle. Subsequently, some of the serum obtained
from one of these was used for passing six more animals through a mild attack of the disease, and these too were
then inoculated in the same way as the first series and serum obtained for them, so that at the present date some
30,000 c.c. of serum have been made. When a centrifugal machine, which has been ordered, reaches the
laboratory, more than twice as much serum will be able to be prepared from the same quantity of blood as is
at present possible. It is worthy of note that out of first bleedings only from 11 to 15 per cent. of serum was
obtained from the blood taken, which was very disappointing. As it seemed probable that the quantity that
separates from the clotted blood would depend on the firmness of the clot itself more than on any other factor,
and as, moreover, it is known that the clotting power of the blood can be very materially increased by the
administration of calcium chloride, it was determined to administer this drug before bleeding the animals.
The result was most satisfactory, as in this way from 30 to 40 per cent. of serum was obtained, and the great
difference between the quantity obtained from animals with and without the use of the drug was repeatedly
verified, as different animals were found to give different quantities of serum. Moreover, it was found that a
greater quantity of serum was obtained by the use of two doses, each of half an ounce, one given the evening
before and the other on the same morning as the bleeding, but some three hours before, than by a single dose
given on the same morning as the blood was taken. All our animals are now treated in this way, and there is
no evidence to show that the quality of the serum is in any way affected by the drug, while, if anything, it
might be expected to lessen the Oedema which sometimes follows the injections of the serum.
"One other point of practical importance which has been worked out in the course of these experiments on
making serum may be mentioned here. The main difficulty in carrying it out is the obtaining of large quati-
ties of virulent blood, for which purpose control animals have to be inoculated and subsequently bled when the
disease has fully developed. As for the sake of economy, the small hill cattle are used for this purpose; it was
found that only some 2,000 c.c. of blood could be obtained from the jugular vein of an animal before heart
failure set in, the flow ceased and the animal shortly after died. On the other hand, by bleeding from the
carotid artery only 3,000 c.c. were obtained, but the process was a peculiarly repulsive one, convulsions being
caused. In South Africa very much larger animals are used, and although they are bled to death, a very much
larger quantity of blood is obtained from one animal, and the process does not require to be repeated nearly so
often as would be the case when hill cattle are used in India. Moreover, on account of the sacreduess of cattle
in India, it is eminently desirable to avoid bleeding this animal to death, but if the amount taken is so
regulated as to allow of the animal going back to his stall and living for a time at least, but very little blood
is obtained and the number of animals sacrifierd is greatly increased.
"Fortunately, a method of overcoming both these objections has been put into practice with most
satisfactory results. It consists simply in the injection into the jugular vein, after taking as much blood
as is required, of an equal quantity of sterilised salt solution of the same specific gravity as the blood
itself, such as is used in the case of transfusion after severe hæmorrhages. In this way the circulation is
restored, and it has been found that 2,000 c.c. of blood can be easily obtained and still the animal walks
back to its stall as if nothing had been done to it, and in fact animals so treated appear to have a better
chance of recovery from the disease than those which are not bled. Moreover, two days later, the process
can be repeated and the same quantity taken, and yet the animal will again walk back to its stall
and often live for some days longer, although, when such large quantities are repeatedly taken, the animal
seldom recovers. In this way, much larger quantities of blood can be obtained, for the process could be
repeated a third time, or larger quantities taken the second time if thought advisable, and at the same time
the slaughter of the animal is avoided. This method has considerably reduced our difficulties in preparing
large quantities of serum, and at the same time has lessebed considerably the number of animals which
it has been necessary to inoculate with the disease for the purpose of obtaining virulent blood.
"Testing the strength of the serum.—Before the serum can be used in outbreaks, its strength has to
be tested on a series of animals in order to find out exactly what dose per given body weight must be used
together with a small dose of virulent blood injected into a different part of the body, in order to produce
a mild attack of rinderpest, with subsequent immunity for life. Eighteen thousand c.c. of serum were recently
mixed together and tested in this way on eight hill cattle and four plain ones in four series, each series receiv-
ing a different dose in proportion to their weights, and the remarkable result was obtained that, although
all the plain cattle, including the one which had the smallest dose, viz., 15 c.c. per 600 lbs. weight,
remained without any marked symptoms of the disease, although two of them had distinct temperature
reactions, yet all the bill animals developed the disease and all but one died of it. A similar result was
obtained when the six animals were salted for subsequently obtaining serums as mentioned above, for
all these were plain animals and had but little reaction, while two hill cattle which were inoculated in
the same way died of the disease, although weight for weight they had received a rather larger dose of the protect-
ive serum than the plain ones. Other hill cattle have since been tested with larger doses of the serum
and successfully passed through a mild attack of the disease, 45 c.c. per 600 lbs. being the dose required
for this purpose.
"It appears, then, that there is a very great difference in the susceptibility of hill and plain animals,
and this fact raises the important question as to whether there may not be a considerable difference in the
liability of different breeds of plain cattle in different parts of India, and renders it necessary to carry
out the simultaneous method of inoculation in several outbreaks with great caution before coming to a