23
The alteration from the large Negri bodies of newly transferred street virus to the minute
and often invisible forms of fixed virus has also its analogy in the changes of form and staining
characteristics which sometimes follow w hen bacilli are artificially cultivated.
The probabilities are then, that fixed v irus after having accustomed itself through
m a n y
generations to an easy vegetative existence in the cells of the central nervous system cannot regain
in a moment the properties which once enabled it to traverse the tissues from a wound until it
reached the brain, and it therefore is comparatively innocuous when introduced into the system
at a distance from the
b r a i n .
Babes (30) in a long paper expresses his belief that Negri bodies as commonly seen in street
virus brains are due to the entrance of a foreign element into the cell, leading to a hyaline, met
-
achromatic appearance and a kind of coagulation necrosis of the protoplasm, whereby the cell
preserves its life, encapsulating the foreign element. The latter also throws out a capsule of its
own. The presence of these bodies in the cells of the hippocampus major shows the latter to be
highly resistant.
He further remarks that no bodies are found in the medulla or anterior horn of the cord—
this by the way we cannot confirm—but merely great degeneration and exudative change
s,
showing that these parts of the nervous system are less resistant than the hippocampus.
Babes finally explains the absence of Negri bodies infixed virus brains, which he accepts as a
fact by the view that the virus has been. strengthened until not even the cells of the
hippocampus
can encapsulate its elements.
This is all pure hypothesis on the part of Babes and. it derives no support from the
observed
facts.
We do not consider ourselves to be in a position as yet to express any definite opinion as
t o
the ultimate nature of Negri bodies, that is, to declare with Babes and. others that the large forms
are simply cell exudates round a tiny foreign element or to give support to those who believe the
whole body to be a kind of protozoon, though what we have seen so far certainly inclines us to
take the latter view. One would scarcely expect an encapsulation on . the part of a cell to present
quite such a definite outline as these bodies always have when well differentiated, nor is it clear
why the bodies, when they are seen in narrow cell processes at a distance from the cell body and
nucleus, should, almost invariably be greatly elongated in form if they are simply encapsula-
tions. A tiny foreign element encapsulated in a cell process would. presumably have a circular
or at most a slightly oval outline. No obvious explanation of the formation of a capsule six
times as long as it is broad strikes one, whereas, if one regards the body as a specific entity, this
elongated, shape would be exactly what would be expected if a compressible body were to be
carried either by the streaming movement of the protoplasm or by its own motive power into
a
cell process narrower than its resting shape.
Prowazek (35), who reclassifies the organisms of Rabies, Hühnerpes, Vaccinia and Variola,
Trachoma and some others under the name of Chlamydozoa, places them somewhat higher than the
bacteria but somewhat lower than the sexually differentiated protozoa, and until some of these
organisms are cultivated in artificial media we shall probably get no further in this direction.
We have so far been able to examine the brains of only two human hydrophobics. No. 1 had
been badly torn about the face by a wild dog. He arrived at this Institute seven days later but
developed rabies during the course of the treatment 21 days after the infliction of the bite. The
brain of the wild dog was not preserved as the patient was in the jungle at the time and. five
days' march from the nearest railway station. The course of the patient's illness was not strictly
typical, he had a temperature of 103° F, vomiting and constipation, later there was inability to
swallow and collection of viscid saliva in the month. No spasms occurred and death followed quite
quietly five days after the first signs of illness were noticed. Sections of cortex and hippocampus
major showed considerable infiltration of leucocytes round the vessels and degeneration of some cells.
No Negri bodies could be detected with Mann' s or U n n a ' s
s t a i n , n o r w i t h e o s i n a n d
methylene
blue used separately and followed by differentiation with alcohol. Many cells, however, were seen
to contain ill-
yellowish, hyaline bodies which took no stain, differing thereby from true
Negri bodies. Other sections stained with Heidenhain's iron hæmatoxylin showed some of
these bodies to be full of deeply stained granules, giving the whole the aspect of a zoogloea.
N o
specimen was secured from the cerebellum. From this brain four sub-passages were made: —
Rabbit 93.—Incnbation 16 days, 21st day. Hippocampus. Mann's stain. True
Negri bodies numerous, mostly small, the largest 5µ. Negri bodies were also seen in the
cerebellum and spinal ganglia.
Rabbit 32.—Incubation 17 days, death 23rd day. Negri bodies as above but smaller and
m o r e s c a n t y .
Guinea pig 42.—Incubation 31 days, death 36th day. Tiny Negri bodies 1µ— 2µ numerous
in parts of hippocampus,c o r t e x a n d c e r e b e l l u m . S o m e c e l l s a l s oc
o n t a i n e d
the
y e l l o w i s h
unstained zooglœa noticed. in the human brain.
Guinea
piq6 4 .
— I n c u b a t i o n
3 3 d a y s , d e a t h 3 8 t h
d a y
. N e g r i b o d i e s v e r y n u m e r o u s1
µ
— 5 µ .