20
REPORT OF THE IMPERIAL BACTERIOLOGICAL LABORATORY,
small cost, to Muktesar. In order to assist us in this respect, customers
were also asked to store as much as they could in cool storage conditions.
Tests upon numerous samples returned from the provinces, because they
appeared to fail to give the expected results in the scene of outbreaks,
have shown, however, that in the storage conditions not uncommonly
adopted in the plains deterioration in potency takes place rather rapidly.
The usual method of preserving serum adopted in the past here has been
to mix the product with one-half per cent. carbolic acid, but tests have
shown that certain, organisms (staphylococci) grow luxuriantly in the
mixture, and it is probable that their prolonged action under favourable
temperature conditions may bring about the relatively rapid deteriora-
tion. It has been found that in the ordinary storage accommodation of
Muktesar a good serum remains potent for two years. Tests upon the
relative efficacy of other preservatives executed by Mr. Bennett have
shown that certain of the cresols, notably 0.35 per cent. orthocresol
in an alkaline medium, is a better preservative. The information now
available tends to show that the most economical procedure for the
laboratory is to manufacture nearly all its annual stocks of serum at
Izatnagar, return them to Muktesar for storage (the cost of return amounts
to less than two per cent. of the sale price and is cheaper than the main-
tenance of a freezing plant at Bareilly), careful tests upon the hill bulls
that are available more cheaply locally, and mixing, and then request
provinces to indent on Muktesar at any one time for little more than the
minimum anticipated requirements to cope with emergencies, so as not
to retain excessive stocks on hand that are likely to have suffered much
deterioration by the time they are needed. As is stated elsewhere in
this report, much progress was accomplished during the period in per-
fecting and cheapening the processes of serum manufacture. This
aspect will be dealt with in the section dealing with Research, but it may
be said here that the progress has consisted in devising means of (i)
producing a serum that is very potent and not toxic for use in the serum
simultaneous method of immunization, (ii) producing a serum for use
in preventive inoculation for a prolonged period from " serum makers "
after the simple initial immunization, and discarding the hitherto adopted
costly and somewhat revolting method of so-called hyperimmunization,
(iii) preparing the annual stocks cheaply at the plains sub-station, stor-
age, and careful testing at Muktesar. Research into this subject was
stimulated particularly by an unusual number of accidents that occurred
among cattle administered large doses of serum during the serum-simul-
taneous inoculations at the Military Dairies in the cold weather season
1922-23. The accidents were traced to the issue inadvertently by the
staff of a serum that had been tested and found satisfactory for preven-
tive purposes, but had been obtained from buffaloes after repeated
"hyperimmunization" with hill bull blood, and hence had acquired
hæmolytic properties capable of producing severe effects when the serum
was injected in large amounts into cattle.
Prior to the cold weather season 1923-24, the circular printed instruc-
tions for the serum simultaneous method were redrafted, and the efficacy