Rabies. 
7 
croscopic study. A sectioned surface of the brain is usually dark in 
appearance. Occasionally a bloody spot, small in size, can be seen un¬ 
der the coverings of the cord. This is especially noticeable from the 
cords of the experimental rabbit inoculations, otherwise the cord 
and brain has a normal appearance. The changes are so slight in 
their appearance that nothing definite can be told short of a microscop¬ 
ic examination. In the stomach may be found sticks, straws, shavings, 
etc, picked up while running at large. Aside from these substances, 
the stomach is empty. There should be observed an absence of all acute 
diseased lesions, at the autopsy. 
Microscopical Examination. 
For microscopical examination, the brain must be in good con¬ 
dition. Brains that are in a state of putrefaction cannot be satisfac¬ 
torily examined. The first definite microscopic lesions of rabies to 
be pointed out, was by V. Babes in 1892. 'He found degeneration of 
the nerve cells in the medulla and the plexiform ganglion. The de¬ 
generation in the medulla was particularly noticeable near the central 
part of the ganglionic portion. There was observed an invasion of 
small round cells in the spaces occupied by the cytoplasm of the cells. 
These he called rabic tubercles which are now sometimes called Babes 
tubercles or corpuscles. Figure 2 shows one of these tubercles from the 
plexiform ganglion. 
In 1893, A. Negri called attention to certain bodies always found 
in the nerve cells of a dog or other animal dead of rabies. To these 
was given the name Negri bodies. Since that time these bodies have 
been studied in more detail by many scientists and are. now believed 
by the foremost workers to be protozoan in nature. Different stages 
of their development have been studied which corresponds to the dif¬ 
ferent stages of the disease. These bodies stain characteristically. 
They contain eosinophilic granules. Figure 3 shows nerve cells con¬ 
taining Negri bodies. 
Delafield & Prudden call special attention to the peri-vascular 
infiltration which usually accompaines this condition. Figure 4 gives 
an illustration of this phase. 
Animal Experiment. 
When a person is bitten by a dog suspected of being rabid and the 
laboratory findings are not satisfactory the laboratory worker can, if 
the brain is still fresh and is not contaminated, inoculate an animal. 
In doing this an emulsion is made from a small part of a certain part 
of the brain. The rabbits skull is trephined and a small part of the 
emulsion is injected under the coverings of the brain. If care, in tech¬ 
nique is taken the animal will appear healthy, and eat and drink until 
the symptoms develop, which is usually about the 14th to the 16th 
day. If the technique has been at fault and infection taken place 
the rabbit will die of septic infection long before the time for rabies 
to develop. Freezing does not destroy the virus and it will resist putre¬ 
faction for a long time. Drying will soon destroy it. 
