14
Baschieri (25) found Negri bodies, small but characteristic, in fixed virus dogs.
Mareschi (26) remarks on the rarity or complete absence of the bodies in fixed virus.
Poor (27) found the bodies in 5 fixed virus dogs and 1 fixed virus guinea-pig.
It may be concluded from these diverse findings that the demonstration of tiny Negri bodies
in fixed virus animals depends chiefly on the methods employed and. on the industry of the
searcher. We have not seriously tried to determine whether merely an industrious search
through numerous sections is necessary in order to prove without fail that certain animal died
from fixed virus infection or not. This much however is evident, that a careful glance through
one or two sections of a hippocampus, which is all that time usually allows when many other
matters are in hand, does nob as a rule suffice to make a certain diagnosis. Of the microscopic
examinations of the brains of fixed virus animals which were made for various purposes we found
.small but distinct Negri bodies in the hippocampi of two rabbits, one goat and two guinea-pigs.
The cerebellum of one of these guinea-pigs showed some of the Purkinje's cells full of quite large
Negri bodies such as might have been found in street virus.*
None of the above quoted authors state distinctly whether the animals they examined had
been infected subdurally or subcutaneously. Thinking that there might be a difference in the
:appearance of Negri bodies depending on the point of introduction of the infecting organism we
examined the brains of a considerable number of animals which had succumbed to subcutaneous
infection with both street and fixed virus with the following results :—
(1) of nine guinea-pigs which each had received a single dose of
of their weight of
fixed virus brain, three showed Negri bodies, 1µ—1.5µ, six showed none ;
(2) three guinea pigs which each had had several doses of fixed virus brain showed no
Negri bodies ;
(3) two rabbits which had had single doses of fixed virus brain showed Negri bodies
1µ-2µ;
(4) of ten guinea-pigs which had had single doses of street brain, five showed Negri
-bodies from 1µ — 5µ five showed none ;
(5) of eight guinea-pigs which had had
1/1,0000 of their weight of street virus cord during
14 days, three showed Negri bodies from 2µ—5µ five showed none ;
(6) of seven guinea-pigs which had had 1/1,0000 of their weight of street virus cord during
14 days, six showed Negri bodies 1µ — 4µ one showed none ;
(7) one rabbit which had had a single dose of street virus brain showed. Negri bodies up
to 5µ;
(8) three rats inoculated with emulsion of the salivary glands of a street virus cat showed.
numerous Negri bodies up to 6µ ;
(9) three rats inoculated with the brains of the above rats showed nothing ;
(10) one monkey which had had a single dose of street virus brain showed Negri bodies
lip to 8µ.
It would appear then that after subcutaneous inoculation of fixed virus brain Negri bodies
.are not more frequently found than after subdural inoculation, nor are they of greater size.
After subcutaneous inoculation of street virus brain, however, we found Negri bodies with
greater frequency but still in only about 50 per cent. of the animals. The bodies were also of
small size. This is a noteworthy fact, especially as we never failed to find Negri bodies very
numerous and often large, up to 12µ or so, after subdural inoculation with street virus.
It may also be noted that the three rats which had been inoculated with street virus salivary
glands showed numerous bodies up to 6µ whereas three others inoculated from their brains showed
no bodies. Bodies, similarly, seem to be invariably present in dogs which have been naturally
Infected by bites, i.e., saliva, so it would appear as if the appearance of Negri bodies; in the brain
depends in some way on the nature of the virus inoculated, the virus contained in the saliva
producing bodies with more certainty than the virus contained in the brain.
With street virus inoculated subdurally we experienced no difficulty whatsoever. Every
inoculation performed with street virus from rabid dogs produced numberless bodies, and once,
when several passages were made, though the incubation period was shortened, the number
'and size of the bodies showed no change (see Table No. 7).
TABLE No. 7.
No.
Animal.
How inoculated.
Incubation.
Negri bodies.
1
Malappuram dog.
Naturally
...
... Unknown ... Numerous.
2
Rabbit ...
... Su.bdurally from 1
... 14 days
...
Do.
3
Guinea-pig
..
from 2
... 13 „
...
Do.
4
Rat
...
...
J,
from 3
,..
9 „
... Fewer.
5
Guinea-pig
...
I,
from 4
...
6 ,.
... As numerous as in
2 and 3.
* Note.—Since then we have found tiny bodies in numerous fixed virus brains.