2
sufficient to mask the deviation due to albuminous substances in the extract of
normal brain which is made
evident by the difference in lysis in columns 5 and.6.
A similar experiment in which the result was more marked is shown below :—
TABLE No. 2.
1
2
3
4
Fresh antirabic horse serum
...
0.31
0.23
0.31
0.23
Extract, F.V. brain
1.2
1.2
Extract, normal brain
1.2
1.2
0.85 per cent. NaC1
0.44
0.52
0.44
0.52
20 per cent. sensitized sheep RBCs
0.25
0.25
0.25
0.25
Lysis.
Slight.
Trace.
Complete.
Nearly
complete.
The extracts were incubated with the antirabic serum for 1½ hours before the
sensitized RBCs were added.
Columns 1 and 2, respectively contrasted with columns 3 and 4, show a
great diminution of lysis due, it may be assumed, to the presence of some substance
in the fixed virus brain extract capable of uniting with the immune body in the
antirabic horse serum and fixing some of the complement. Other experiments
made with the antirabic serum of a goat failed to show any deviation.
The points which govern the semblance of a successful reaction are not clear,
and no explanation can be offered as to the reasons why deviation should be
manifested with some extracts and not with others, with some antirabic serums and
not with others.
The fact that it is sometimes manifested is of importance in proving the
existence, on occasions at least, of some soluble product of the rabies organism in
the brain ; but in view of the many failures and few successes one must be prepared
to admit that the successes are coincidences depending on unknown causes.
2. Reduction of Methylene Blue by Fixed Virus.
There is a distinct difference in the amount of decolourization of a watery
solution of methylene blue produced by F.V. compared with that produced by
normal brain substance. As is well known, extracts of normal organs containing
cell débris have the power of decolourizing dilute solutions of methylene blue owing
to the presence of a reducing substance which is freed by the mechanical destruc--
tion of the cells. The liver is particularly active in this respect, the brain much
less so. The activity is destroyed by boiling the organs.
Since the blue colour returns to the solution, gradually on exposure to air,
rapidly on shaking and instantaneously on the addition of hydrogen peroxide, the
experiment must be conducted anærobically. The simplest way to secure the
exclusion of oxygen is to pour on to the surface of the fluid in each tube about 1 cm.
in depth of melted vaseline.
Exactly similar filtered emulsions of fixed virus and normal rabbit brains were
prepared. A series of tubes, each containing 5 cc. of a dilute solution of methylene
blue, were put up, and varying proportions of the brain emulsions were added.
The contents were well mixed, sealed with vaseline from contact with the air and
incubated for 24 hours. A greater degree of reduction was on each occasion
observed in the tubes containing F.V. emulsion than in those containing normal
brain emulsion. The significance of this observation is open to question ; the
reaction is probably not due to specific reducing bodies formed by the organism of
rabies, though it may be due indirectly to the irritant or destructive action of this
organism on the nerve cells. The experiments were made with the view of finding
an easy, rapid test tube method of differentiating between a rabid and a normal
brain, but the process could not be usefully adapted to this end.