432 
Journal of Agricultural Research 
Vol. XXX, No. 5 
This technic is followed more or Jess 
closely by the majority of the com¬ 
mercial houses manufacturing this 
product. In several instances, how¬ 
ever, the fixed virus is killed by phenol, 
the resultant vaccine being a killed 
rather than an attenuated fixed virus. 
SOURCE AND DOSAGE OF VACCINES 
The vaccines used in the following 
experiments consisted of several lots 
prepared in the laboratory of the 
Bureau of Animal Industry, and of 
lots obtained from commercial houses 
manufacturing this product. The vac¬ 
cines prepared in this laboratory were 
made according to the*’method of 
Umeno and Doi, with the attenuation 
taking place at room temperature for 
two weeks. The dosage was 3 c. c. 
for dogs under 20 pounds, 5 c. c. for 
dogs between 20 and 40 pounds, and 
10 c. c. for dogs over 40 pounds. 
The commercial vaccines were re¬ 
ceived in original sealed containers and 
were kept in the ice box until used. 
The dates on which the vaccines were 
used were well within the expiration 
dates marked on the outside con¬ 
tainers, and the dose given was accord¬ 
ing to the manufacturers’ directions. 
EXPERIMENTAL DATA 
METHOD OF INJECTION 
The loose skin back of the shoulder 
or elbow of the dog was shaved, the 
skin disinfected with 3 per cent phenol, 
dried, and painted with 3.5 per cent 
tincture of iodine. The proper amount 
of vaccine was then slowly injected 
subcutaneously in two or three places. 
After varying intervals of time the 
vaccinated dogs, together with a num¬ 
ber of control dogs, received an intra¬ 
ocular injection of rabies street virus. 
EFFECT OF THE INJECTION OF VACCINE 
The dogs were not inconvenienced by 
the injection of the vaccine. They 
remained lively and ate heartily at all 
times. In one case, however, the in¬ 
jection of the vaccine resulted in a 
death from rabies. Dog 440 was in¬ 
jected with 5 c. c. of Bureau of Animal 
Industry vaccine No. 1 on May 25, 
1922. On September 13, 1922, the 
dog showed signs of paralysis and on 
September 14 was stretched out on its 
side, completely paralyzed. It con¬ 
tinued in this condition through Sep¬ 
tember 15, and was found dead on the 
morning of September 16. Micro¬ 
scopic examination of smears from the 
hippocampus revealed the presence of 
a few small Negri bodies. 
Three rabbits inoculated subdurally 
with brain material from dog 440 were 
completely paralyzed on the seventh 
day after inoculation and died two to 
three days later. Microscopic examina¬ 
tion of the brains of these three rabbits 
revealed the presence of a few small 
Negri bodies of the type usually seen 
in fixed virus. 
Reinoculation of rabbits with the 
brain of one of these rabbits was fol¬ 
lowed by typical rabies paralysis in the 
inoculated animals on the seventh day. 
Several more passages of this virus 
were made in rabbits, and in every 
instance complete paralysis occurred on 
the seventh day. 
These inoculation results clearly indi¬ 
cate that dog 440 died of rabies fixed- 
virus infection. Three other dogs 
received the same amount of this 
vaccine and on the same day as dog 
440, but remained perfectly healthy. 
This was the only case of death as a 
result of the injection of the vaccine. 
METHOD OF EXPOSURE TO STREET VIRUS 
One of the difficulties encountered in 
experimental work on rabies immuni¬ 
zation is the question of the mode of 
exposure and the amount of street virus 
to be injected. It is extremely diffi¬ 
cult or impossible to standardize street 
virus, owing to the variable action of 
the same amount of virus on different 
individuals. Probably with no other 
disease does individual resistance play 
so important a part as in rabies. What 
is highly virulent for one dog may not 
be sufficient to cause the development 
of the disease in another. 
For an experiment to be successful 
the exposure to street virus should be 
sufficiently virulent to cause the devel¬ 
opment of the disease, if not in all, at 
least in the great majority of the con¬ 
trol dogs. On the other hand, the 
virus should not be so virulent as to 
be simply overwhelming. 
The intraocular injection is a severe 
test, probably much more so than an 
animal would encounter naturally. 
However, as an experimental means of 
exposure it is probably better than any 
other method. Umeno and Doi, Eich- 
horn and Lyon, and Reichel and 
Schneider report the use of this method 
in experimental work, and it is the 
method used in the following experi¬ 
ments. 
EXPERIMENT NO. 1 
On May 25,1922,7 dogs each received 
one injection of vaccine. On July 18,11 
