402 RABIES 
by Pasteur to virus that is so exalted in virulence by successive passages through rabbits 
that it will produce the death of these animals in six or seven days. Beyond this point 
no increase of virulence can be obtained; hence the name, fixed virus. The spinal cord 
is removed aseptically from rabbits killed by the inoculation of fixed virus, cut into 
three pieces and suspended over a solution of caustic potash in a drying chamber. 
Here the cords are kept in the dark and at a constant temperature of 23° C. for fourteen 
days. Emulsions of the dried cord are prepared in sterile salt solution or broth and 
injected every day, or sometimes more frequently, during a period of fifteen to twenty- 
one days, the interspacing of doses and duration of treatment being determined by the 
nature of the case. As a rule, the most attenuated material (fourteen-day cord) is 
injected first, and this is followed by virus of gradually increasing strength. The 
method is essentially one of active immunization, and involves a race between the 
action of the attenuated virus and the virulent virus introduced by the bite of a rabid 
animal. It follows that the preventive treatment must always be begun at the earliest 
possible moment after the bite. In a certain proportion of cases a spinal cord lesion 
seems to follow the treatment. 
“The serum of animals immunized against hydrophobia possesses considerable pro- 
tective power, and according to some investigators, has also a marked curative effect. 
Favorable results have been reported from the use of immune serum, especially in cases 
of severe bites about the head, or in persons who have delayed beginning the Pasteur 
treatment. 
“Hoégyer produced immtnity in dogs by injecting them subcutaneously with emul- 
sions of virulent spinal cords in normal salt solution in high dilutions. Galtier immun- 
ized sheep and goats by injecting saliva and also medulla oblongata into the jugular 
vein. Babes injected sheep subcutaneously with normal cerebral tissue and found them 
resistant to subsequent infection with virulent cord.” 
Semple’s antirabic vaccine. This method of anti-rabic vaccination was introduced 
by Lieutenant-Colonel Sir D. Semple. An eight per cent. dilution of rabies virus is 
made in normal saline, and one per cent. carbolic acid is added; the resulting mixture 
is then kept at a temperature of 37° C. for twenty-four hours. By this means the virus 
is killed. The mixture, diluted with an equal bulk of saline solution, gives a vaccine 
containing four per cent. virus (dead) and 0.5 per cent. carbolic acid. This conferred a 
high degree of immunity in monkeys, dogs, and rabbits, and the serum obtained from 
these animals had a well-marked rabicidal action on living virulent virus. Its efficacy 
was apparently as great as that obtained by the use of living virus, and it retains its 
power for some time.” 
Eradication. The eradication of rabies infection resolves itself into 
two procedures. (a) The destruction of all ownerless and vagrant 
dogs, and (b) the muzzling of all dogs that appear upon the streets or 
in public places. In thus preventing the propagation of the virus, as 
shown by the results obtained in Germany and Great Britain, the 
disease will be practically exterminated. 
REFERENCES 
1. Bases. Sur certains caractéres des lesions histologiques de la rage. Ann. de 
*l Institut Pasteur, Vol. VI (1892), p. 209. 
