9
and 181 is therefore no proof that they did not die from the street virus infection and the
fact that Negri bodies were recovered in a sub-passage from No. 115 makes it clear
that that animal at least died from street virus infection. Sub-passages were not made
from No.84 and No. 181, so, it remains uncertain whether they succumbed to street
virus or fixed virus infection.
(2) Six other guinea pigs were inoculated subcutaneously in the back with first
passage street virus brain.
On the next day protective subcutaneous injections with fixed virus were begun. In
all fourteen injections, amounting to 1/10,000 of the animal's weight of fresh fixed virus
were given in the abdomen at a distance from the street virus infection unless death
occurred before the end.
One of the six survived. Of the remaining five
No. 80 died on 14th day.
" 5 A "
1 3 t h "
" 9 1 "
1 3 t h "
" 6 5 "
1 4 t h "
" 5 0 "
1 2 t h "
No. 80 showed no Negri bodies, no sub-inoculation made.
No. 5A showed Negri bodies to 1.5µ
No. 91 showed Negri bodies to 5.0µ in sub-passage Negri bodies to 4µ
No. 65 showed. Negri bodies to 3.0µ no sub-inoculation made.
No. 50 showed no Negri bodies, no sub-inoculation made.
Whether Negri bodies were found or not it is probable that all these five animals
succumbed to the street virus infection.
It follows either that street virus infects guinea pigs with greater certainty and
more rapidly when inoculated beneath the skin of the back than it does when inoculated
beneath the skin of the abdomen, or else that fixed virus injected round the site of the
street virus infection has greater protective power than when injected at a distance
from the infected part.
The experiments merely indicate the possibility that protective injections might
have more effect if a local immunity in the neighbourhood of the point infected were to
be aimed at instead of a general immunity. They prove nothing except that guinea
pigs are far too susceptible to both street virus and fixed virus subcutaneously to
be suitable animals for this class of experiment.
The idea seems to be gaining ground that, after a natural infection with street virus
through the bite of a rabid animal, the virus frequently becomes rapidly disseminated
by the blood and lymph streams, and does not merely lie in the wound and travel
slowly to the central nervous system along the nerve trunks. If this be so, there
would be little gained by endeavouring to excite a more intense immunity of the
tissues in the neighbourhood of the point of infection.
5.—Is the virus of rabies destroyed at the point of introduction or does it
lie latent in the subcutaneous tissue ?
(1) Each of two guinea pigs was inoculated subcutaneously in the midline of the
abdomen with 0.3 gramme fixed virus rabbit brain suspended in 1 cc. salt solution.
Six days later they were killed. and the subcutaneous tissue at the site of the
inoculation was dissected out. In one animal there was no trace of the inoculum ; in
the other there was a nodule of the size of a pea. The tissues removed by dissec--
tion were pounded up and inoculated subdurally into another guinea pig, which
survived.
(2) A. tiny nodule was removed from the subcutaneous tissue at the site of inocu-
lation of a rabbit which had. succumbed to fixed virus injected subcutaneously. It was
emulsified and. inoculated subdurally into a guinea pig, which survived.
Microscopic sections of these subcutaneous nodules show them to consist mainly
of a collection of eosinophile leucocytes.
It must be concluded that fixed virus, at any rate, if introduced into the subcutane-
ous tissues, is rapidly destroyed and that after six days a sufficient quantity cannot be
collected at the site of inoculation to infect a guinea pig subdurally. In spite of this
the subcutaneous inoculation may cause rabies.
3