ANTI-RINDERPEST INOCULATION OF CATTLE                  7

immediately on receipt from the laboratory. If this is not possible, the virus may
be stored for one or two days upon ice, provided only that the containers remain
unopened. It should be taken as an invariable rule that once the sealed container
has been opened, its contents must be used that very day or else it must be dis-
carded and a new consignment sent for.

         The dose of virus to be injected into cattle undergoing immunisation need not
be gauged with any pretence at accuracy since a minute quantity only of virulent
blood is necessary to infect. The usual dose is from ½ c. c. to 1 c. c. of blood.
Larger doses up to 5 c. c. or more are usually employed for controls, but the degree
of reaction is not influenced by the dose of virus administered.

                           11. SECOND INJECTION OF VIRUS.

         Provided that an animal receives a dose of certainly virulent virus at the
first injection, no further injection is theoretically necessary. In practice, however,
it is strongly recommended that a second injection of virus be given to all animals
except those in which a definite temperature reaction has occurred between the
third and fifth days after the first injection. The dose of virus usually employed for
the second injection is 5 c. c. and can conveniently be obtained from cattle or
goats used as controls during the first injection. If it is desired to make certain
that virulent blood will be available for the second injection then arrangements
should be made beforehand for a second consignment of virus to arrive from the
laboratory within eight days after the first injection. Since the protective effect
of anti-rinderpest serum lasts only for nine days it is imperative that the second
injection be given well within this period. It has already been pointed out that the
locally produced virulent blood from the controls to the first injection will be avail-
able either on the fourth or fifth day, and this arrangement is therefore a very
convenient one. Since second injections of virus are intended to "catch" the
animal that has escaped receiving a dose of virulent blood at the first injection
the second injection must be given while the serum is still conveying a passive
immunity to the animal, that is, within the nine day period after serum inoculation.

                           12. CONTAMINATED VIRUS.

         A sample of every consignment of virus is submitted to bacteriological
examination before despatch from the laboratory, but the results of the examina-
tion are not known until 2 days later. If the sample is found contaminated with
extraneous organisms a telegram is sent immediately to the customer advising
withholding use of the virus. When bacteria are detected they are nearly always
in themselves harmless in their effects when injected into an animal, but their