RABIES 397 
In 1900, the discovery of changes distinctive of rabies was an- 
nounced by Van Gehuchten and Nélis. These were found in the 
peripheral ganglia of the cerebrospinal and sympathetic systems and 
are especially marked in the plexiform ganglion of the pneumogastric 
nerve and the Gasserian ganglion. Normally these ganglia are com- 
posed of a supporting tissue holding in its meshes the nerve cells, each 
one of which is enclosed in a capsule, made up of a single layer of 
endothelial cells. The action of the rabic virus seems to exercise its 
effect on these cells particularly, bringing about an abundant multi- 
plication of the cells forming this capsule, leading finally to the com- 
plete destruction of the normal ganglion cell and leaving in its place a 
collection of round cells. Ordinarily a considerable number of gang- 
lion cells will be found which have undergone only a slight change, but 
under certain conditions the process is so widespread that all the 
ganglia cells are destroyed. The intensity of these changes varies in 
different animals; they are perhaps most pronounced in the dog, less 
marked in man and still less in the rabbit. 
Diagnosis. Rabies is diagnosed by the symptoms, presence of 
Negri bodies, lesions in the ganglia, animal inoculation and by the 
complement fixation method. 
Diagnosis by the presence of Negri bodies. The presence or absence 
of Negri bodies has come to be used as a means of diagnosis in most 
if not all laboratories. These bodies, which are often quite large, are 
readily brought out by proper staining. Whether the cause or a 
specific degeneration, they are of much value in making a rapid 
diagnosis. Unlike the ganglion changes they appear early in the 
course of the disease, and consequently they are of value in making 
an early diagnosis when the animal is killed soon after the appearance 
of the first symptoms. Thus far these bodies have not been found in 
the brains of animals dying from other diseases except one report of 
their possible presence in a case of tetanus. They are found prior to 
the appearance of symptoms. 
Bohne uses for diagnosis of rabiesa piece 14-34 mm. thick from the 
Ammons horn which after 30 to 40 minutes of fixing and hardening in 
acetone for 60 to 75 minutes he puts in paraffin. In this way it is 
possible for one by the aid of a short staining after the Mann method 
to get stained sections in the course of three hours. In his 170 
investigations (157 dogs, 6 cows, 4 people, 3 cats) he confirmed the 
later discoveries of Negri and Volpino relative to the presence of the 
Negri bodies and their finer structure. He examined 50 dogs attacked 
