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or other piroplasms, might be twofold in origin: first, the virulent
blood itself might contain infective piroplasms, in which case symp-
toms of redwater would occur after an incubation period of seven to
nine days, while on the other hand, the inoculated animal might suffer
an attack of acute piroplasmosis due to the resuscitation in virulence,
owing to the depressant effect of the rinderpest infection, of piro-
plasms lying dormant in the animal's system and kept in a latent
state subsequent to a former, natural piroplasm infection,—in
which event the symptoms might appear at any time, early or late,
during the course of the reaction. The very common small piro-
plasms Theileria mutans, that frequently appeared in the blood
of inoculated cattle, did not seem to exert an invariably distinctly
prejudicial effect.

    He had again been perturbed concerning the possibility of
mutation in the virus, for it was well known that in other diseases
due to filterable viruses—horse-sickness, in particular, swine fever,
and, according to recent reports of French investigators, the foot
and mouth disease virus—various strains existed which differed
greatly in their behaviour towards a protective serum prepared
against a single strain. He was conducting experiments bearing
upon this point, but had hitherto obtained no evidence of such
mutation.

    As had been said before, the information of other countries
appeared to show that with few precautions the mortality rate due
to any of these factors was a very small one when large numbers of
cattle were inoculated, and in other countries the prolonged observa-
tion of inoculated cattle which was generally undertaken in India
was not usually made. He had already performed the simultaneous
inoculation quite successfully upon a number of young calves kindly
sent to him for this purpose by Colonel Matson, Controller, Military
Dairy Farms, and upon calves specially reared at the laboratory.
He proposed to test the durability of the immunity conferred upon
these calves at various intervals; tests hitherto conducted showed
that it remained solid for a year, and there was no reason to believe
that it would not last many years. A great advantage of immun-
izing young calves in this manner was, as was well known, their
relatively high resistance towards the severe effects of an accident-
ally transmitted redwater infection.

    Although the "serum simultaneous" method was the method of
choice where it could be applied, the "serum alone" method had
its indications for adoption and he saw no reason why this method
should not be pursued to the utmost possible extent pending the
development of circumstances favourable for the general application
of the former method. In the first place, anti-rinderpest serum