The experiments detailed here tend to the following conclusions:-
(1) Slight persistent local reactions may sometimes be expected to
follow inoculation with blackquarter vaccines precipitated by
alum or aluminium hydroxide.
(2) Blackquarter vaccines containing alum afford a very strong protection
against the disease.
(3) The immunity from the best vaccines at present in use becomes
gradually reduced after six to twelve months.
(4) There is probably some diminution in the efficiency of all types
of blackquarter vaccine after 6-12 months, but a fairly good
protection was still afforded by one-year-old vaccine.