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6. NEGRI BODIES.
BY
J. W. CORNWALL AND M. KESAVA PAI.
The presence of the bodies first described by Negri in 1903 in the cells of the nervous system of
all animals, including man ; which have died of naturally acquired rabies seems now to have been
established beyond dispute, and so invariable is their occurrence that in some Institutes, e.g.,
Turin and Algiers. the microscope is exclusively relied upon to determine whether a suspected
animal has died of rabies or not.
No similar appearances have ever been noticed in the nerve cells of animals dying from other
causes, or in healthy brains with the single exception of that of the cat to which we shall. recur.
Negri bodies are generally so numerous that an examination of a single section of the cortex,
cerebellum or hippocampus major 'brings dozens or even hundreds into view. It has been affirmed
that they are occasionally absent from the hippocampus while present in the cerebellum or vice versa,
but our experience has been that if they appear in the one they also appear in other parts. It
has also been reported that they are occasionally so few and far between that a long search of
many sections only reveals one or two. This has not yet occurred to us.
That they tend to occur in clumps there is no doubt ; for, in sections of cortex, hippocampus.
and cerebellum some parts may be found practically free while others will be crowded with the
bodies. The hippocampus major is usually regarded as the seat of election of these bodies, and it
is the part of the brain one naturally turns to in making sections for the microscopic diagnosis,
but this is more on account of the number of large ganglion cells found in that situation, which
renders the recognition of the bodies easy, than because it is le seat of a specific lesion.
Nearly as many and nearly as large Negri bodies can be found in both the cortex and the
cerebellum, but the size of the bodies depends on the size of the cell that contains them, and,
though they are easy to see in the large hippocampal ganglion cells, the oval cells of the cortex
and Purkinjes cells in the cerebellum, they may be quite difficult to find in the small cell layer of
the hippocampus and the small pyramidal cells of the cortex, and cannot be seen at all in the
small cells of the cerebellum.
When we leave the brain and examine sections of the spinal cord Negri bodies are not found
with such ease, but a greater degree of degeneration of the nerve cells is met with than is common
in the brain.. The ganglia on the posterior nerve roots, however, with their large cells afford
excellent pictures, and. the degenerative changes induced by the Negri bodies can be studied here
perhaps more easily than elsewhere.
It is by no means the case, as some authors would have it, that the presence of Negri bodies.
has no effect on the including cell or that the bodies are seen only in cells that are apparently
quite uninjured.
Two or three bodies, it is true, may frequently be seen in apparently uninjured cells in which
the cytoplasm, nucleus and nucleolus are all as clearly defined as in a healthy brain. and it is in
such cells that the clearest view of the inner structure of the bodies is obtained.
One may find on the other hand numerous cells the nuclear structure of which has been.
entirely disintegrated, and the bodies, perhaps a dozen in number, which occupy the badly
staining cytoplasm may be themselves in consequence ill defined. Other disorganised cells may be
seen in which no bodies can be distinguished. A peculiar and most important difference between
natural rabies and the rabies which has been passed. through hundreds of rabbits subdurally and is
known as the fixed virus of antirabic institutes is the fact that. whereas Negri bodies are abundant
and easily recognised in the former ; in the latter they are either absent or so small as to be seen
with difficulty.
This finding is not upheld by other workers, although Negri himself started by announcing
that he could not see his bodies in fixed virus brains.
Bongiovanni (20) was unable to find Negri bodies in any of the fixed virus brains he
examined even when the incubation had been prolonged far beyond the. normal by the radium
treatment initiated by him and Tizzoni. He considered that this disposes of the idea that the
absence of the bodies can be accounted for by the lack of time for their proper development in
the ordinarily rapid. course of the fixed virus disease.
Lentz (21) found them in fixed virus in 7 out of 20.
Fursenko (22) found them is all of 10 fixed virus rabbits in hippocampus, cerebellum,.
medulla or cord, but he had a look over as many as 12 preparations from each situation.
A few large forms were seen hut most were small, from 1p.-5p..
Manouelian (23) found tiny bodies in 102 fixed. virus rabbits, obtained from the Paris.
Institute, in large numbers in cortex and hippocampus. In 8 of these he also saw large bodies.
comparable with those found in street virus. ,
Williams and Lowden (241 saw numerous bodies in fixed virus.
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