CORRESPONDENCE.
119
dose ' of known virulence. The attempted analogy between Schern's cases and
those of Mr. Purvis is not clear, since the cases of the former gentleman received
rinderpest blood only and his virus appears to have been potent judging by the
97 reactors and the finding of post mortem lesions, in the non-reacting 34, simulat-
ing findings in natural cases in the experience, among others, of Littlewood [1905]
in Egypt (p. 366 our article). In regard to Mr. Purvis's Kenya experience, which
it may be noted was not controlled, the allegation that virulent blood failed to cause
infection in susceptible animals is untenable, because, as he rightly infers later,
it was a matter of anti-serum counteracting a doubtful or weak infection " as the
quarantine station was too far from the centre of production of virulent blood which
was therefore too old for use ". A similar experience in South India may be recalled.
In an outbreak amongst a valuable imported Holstein herd including cross-breds
full doses of a highly potent serum for protection in the face of the outbreak were
given. On arrival four or five days later, the officer, who was specially deputed to
carry out the serum-simultaneous inoculation on these animals, made ' assurance
doubly sure ' by giving the full scheduled doses of serum without making allowance
for the previously administered anti-serum. There was nothing the matter with
the virus employed, as the same was prepared locally, used hot and fresh after with-
drawal, and successfully caused symptoms and death in the controls. Yet many of
these animals succumbed to another outbreak about a year later, whereas the same
officer's technique had succeeded in establishing a solid immunity in another herd
immunised simultaneously, which was healthy and free from rinderpest and where
no overdosing with serum took place. Parenthetically, it is for this reason that
the dosage of serum in the serum-simultaneous work has to be controlled carefully.
Further the position taken by Mr. Purvis is self-contradictory since if Schern actually
had rinderpest in the neighbourhood of his experiment, his virus could not be " still
older " (than what ?). In extenuation of Schern's having rinderpest in the neigh-
bourhood, it must be remembered that as this fragile virus is incapable of being arti-
ficially cultured, only those having a rinderpest station in close quarters could
contemplate any intensive, exact and controlled work. Further we have his word
in the reply to Ruppert that as one experienced in rinderpest work, he knew what
he was doing and that proper measures had been taken to preclude accidental
infection.
6. The quotation from Bliss is not a mere theory but a reasonable enumera-
tion of certain epizootiological observations of his.
7 and 8. Of the two possibilities, the weight of evidence is on the side of the
conclusion that carriers do exist, though rarely. The standing of Curasson and
Jacotot in the domain of rinderpestology, and the fact that the observations in
question relate to the present decade, when considerable knowledge of the nature
of the virus is available, certainly justify a less critical outlook than had hitherto
been possible, and these considerations exclude the likelihood of infection from
other sources. The criticisms of these workers are, however, primarily for them
to reply to.