6
The figures show that there is undoubted diminution of virulence due to the
action of glycerine, whether pure or diluted with salt solution : but no relation
between the length of time the material was kept and its virulence is apparent.
The chief point brought out is the much greater proportion of infections obtained
with the material preserved in 50 per cent. glycerine than with that preserved in pure
glycerine (80 per cent. against 46 per cent.), 25 per cent. glycerine, however, seems to
be a worse medium than 50 per cent. glycerine, giving an infection rate of 56 per cent.
though this number is based on fewer figures. The average incubation period is in
conformity, being 7 . 7 days for the material prescribed in 50 per cent. glycerine, 9.3
days for pure glycerine and 12 days for 25 per cent. glycerine.
The conclusions to be drawn are—
(1) that fixed virus deteriorates, though to an unknown degree, when kept even
for as short a time as 48 hours in contact with pure glycerine at the temperature of
the ice box, 5° C to 10° C ;
(2) that 50 per cent. glycerine is a better preservative than either pure or 25 per
cent. glycerine and that this medium should therefore be selected for the preservation
of brains sent from a distance to an antirabic institu to for the biological test.
2.—On the susceptibility of Monkeys to Rabies.
(1) Of 10 monkeys, inoculated once subcutaneously in the abdomen with street
virus brain matter from dogs and rabbits in varying quantities
—
4 developed rabies within 12 weeks. Subdural sub-inoculations were made in
guinea pigs from the brains of two of these monkeys, one was positive with an incuba-
tion of 9 weeks and the other negative.
2 died otherwise after 12 weeks.
4 survived more than 12 weeks, but succumbed to street virus injected intra-
ocularly, showing that they had not been immunised.
(2) Of 7 monkeys, inoculated once subcutaneously in the abdomen with fresh
fixed virus brain matter from rabbits, 1/10,000 of the body weight being injected in
each case, all survived up to 10 weeks-
4 died otherwise between 10 and 13 weeks.
(No Negri bodies, sub-inoculations in guinea pigs negative.)
3 succumbed afterwards to inoculations of street virus, two intraocular and one
subcutaneous, showing that no immunity had been established.
(3) Of 5 monkeys, inoculated once subcutaneously in the abdomen with fresh
fixed virus brain substance from rabbits, 1/1,000 of the body weight being injected in
each case—
all survived up to 10 weeks.
2 died otherwise after 10 weeks.
3 succumbed afterwards to street virus inoculations, two subcutaneous and one
intraocular, showing that no immunity had been established.
(4) Of 10 monkeys, inoculated daily for 14 days subcutaneously in abdomen with
fresh fixed. virus brain substance from rabbits, 110,000 of the body weight being
injected altogether
—
4 survived from 10 to 19 weeks.
(When dead there was no microscopic evidence of rabies and all sub-inoculations
in guinea pigs were negative.)
2 died before 10 weeks.
(No evidence of rabies, both sub-inoculations in guinea pigs were negative.)
1 survived 12 weeks and then succumbed 11 days after intraocular injection
of street virus (Negri bodies plentiful).