DIAGNOSIS OF RABIES 127 
During the period of incubation the temperature of the 
rabbits remains normal. As the time approaches for the first 
symptoms to appear there has been in the animals tested an 
elevation of temperature of from 1° to 2°, which continued 
for a variable length of time, but rarely longer than 2 days. 
This is followed by a gradual but usually rather rapid drop to 
the subnormal, which continues to the end. 
(2) The diagnosis by means of the changes in the Gasserian 
ganglia, described by Van Gehuchten and Nelis, has proved to 
be very satisfactory where the suspected animal has died or 
was killed in the late stages of the disease, or when Negri 
bodies cannot be found or cannot be looked for because of 
putrefaction, the destruction of the brain, etc. When sections 
are made from the ganglia removed during the first stages of 
the disease, the apparently specific lesions are often absent or 
not sufficiently well marked to warrant a diagnosis. The 
changes may be of two kinds; namely : 
The typical, or focal, lesions. These are characterized by 
the partial or complete destruction of the ganglion cells, their 
place being occupied by cells of the endothelial type. The 
foci may consist almost entirely of cells of the endothelial 
type, but often associated with them are mast cells, lympho-- 
cytes, plasma, connective-tissue cells, and polymorphonuclear 
leucocytes. 
The atypical, or diffuse, lesions. These are characterized by 
a more or less general infiltration between the ganglion cells 
and nerve fibers of cells of an endothelial origin and the various 
cells which are associated with chronic inflammatory processes. 
These changes are usually associated with the typical lesions. 
The lesions in the ganglia may be very extensive, involv- 
ing the entire ganglion, or they may be restricted to a single 
ganglion cell here and there in the organ. The lesions may 
be present in one ganglion and not in another. It is some- 
times necessary to examine a number of sections before finding 
the changes. 
