11
f both cervical and lumbar cord, one batch of patients might get nothing but lumbar cord.
-throughout their whole course and another nothing but cervical cord. The latter batch would
therefore have received doses ten times as powerful as the former.
In practice, so far as we know, no institute makes any difference between cervical and lumbar
cord, all the fragments are classed alike.
Some workers state that subcutaneous injections of normal brain substance produce as high a
state of immunity as injections of fixed -virus. Others state that no immunity follows injections
of fixed virus the virulence of which has been destroyed. by any agency. The same agency
'presumably also nullifies the immunising power of fresh nervous matter. If the former are
correct, then in institutes which use fresh cords it does not matter to a patient whether he gets
highly virulent cervical cord or lumbar cord of low virulence, i.e., approaching normal nervous
tissue ; if the latter, in institutes which use attenuated material, a patient who by chance got
nothing but emulsion of lumbar cord would at the end of his course be in a far worse position as
regards immunity than one who had received cervical cord throughout. It is just possible
tha some of the failures have been due to this cause.
It has become a tradition to use only the spinal cord in the treatment of patients, but if the
relative infectivities of the cord and brain are established there seems to be no reason why the
brain should not be used. as well, and many reasons why it should, notably the lessened number
of rabbits that would be required.
The brain of a rabbit weighs about 1½ times as much as the whole spinal cord, and, assuming
that the brain as a whole is ten times as infective as the spinal cord as a whole, it is evident that
-1 cc of brain emulsion would be an equivalent dose to 1 cc cord emulsion. Pursuing the suppo-
sition, it follows that, if the spinal cord of one rabbit were to suffice for 10 patients, the cord
t o g e t h e r w i t h . t h e b r a i n o f t h a t r a b b i t w o u l d s u ff
i c e f o r 1 0 + 1 5 0 p a t i e n t s , a n d t h e r e w o u l d b e a
corresponding diminution, namely to one-sixteenth, in the number of rabbits employed for the
treatment.
According to Fermi (15) at Sassari the incubation period of fixed virus inoculated subdurally
is very regular when dilutions of not more than 1 in 5,000 are used, but becomes irregular, up
to 30 days, for dilutions between 10,000 and 50,000.
Nitsch (16) at Cracow states that the gray matter of the frontal convolutions is the most
virulent part and that dilutions of this to 1 in 1,000,000 will always infect rabbits subdurally ;
that 1 in 5,000,000 sometimes infects and that 1 in 10,000,000 is harmless.
Poor (17), working in New York, found that the brain infected rabbits in dilutions of 1 in
5,000,000, whereas 1 in 10,000 of the cord was required.
In another place (18) Fermi declares that there is no difference in the number of germs
contained in the hippocampus major, the cerebellum and the medulla,.but that the number in the
frontal lobes and the extremity of the lumber cord is much less. He estimates the proportion of
germs by the degree of dilution required to convey subdural infection and mentions that with the
frontal lobes, lumbar cord and dorsal cord 1 in 30,000 caused rabies, but with the occipital lobes;
caudate nucleus and white matter 1 in 30,000 did not cause rabies.
Our own results with fixed virus rabbits are exhibited in the subjoined table in which the
+ and — signs stand for positive and negative results and the figures in brackets after a sign give
the duration of the incubation period when it departed from the normal 6 or 7 days.
TABLE No. 5 showing the positive and negative results of subdural inoculations with emulsions
of diff erent parts of the central nervous system diluted to various degrees.
Part used for emulsions.
Dilutions employed.
100.
1,000.
5,000.
10,000.
25,000.
50,000.
Lumbar cord
+++ (12)—
— — — — +
—
—
Dorsal cord... +
+ +
(11)
+ — —
—
—
Cervical cord
+ +
+ + (14) —
—
—
—
Cerebellum ...
...
... + + —
+ + — —
+ + (11) — — — —
+ (10)
Motor cortex
+ +
+ + + —
—
—
+
Frontal lobe
+ +
+ + +
—
+
+
Hippocampus major
+ +
+ + +
+
+
+
Whole brain
•••
•••
...
..
+—+
+
++++
+ —
..
Whole cord.
...
...
+
+ + + + .
+ + + + (23) — --