Medical Officers of the Army of India.

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       The plasma was injected subcutaneously in several places. No attack of
spirillum fever followed.

       The control monkey, S-25, had its spleen removed also on February 1st.
It received 2 c. c. of the same spirillum blood as monkey S-26. As a result it
suffered from a typical attack of spirillum fever. This attack lasted for three days
and was terminated by crisis in the ordinary way, the spirilla at the same time
disappearing completely from the blood.

       It may be noted in passing that this recovery of a spleenless monkey does
not confirm the observations of Soudakewitch 9. This observer produced the
disease in two monkeys from which the spleen had been previously removed. In
these cases the spirilla did not disappear from the blood at the usual time of
crisis, but rather increased in number and a fatal result followed.

       Further I have notes of another monkey which was inoculated with spirillum
material 5 days after its spleen had been removed. This animal received 1
c.c. of the spirillum blood by intra-peritoneal injection and 4 c. c. under the skin.
As a result it suffered from a characteristic attack of fever with spirilla in the blood.
This attack lasted for 3 days and terminated by crisis, the spirilla at the
same time disappearing from the blood.

       The conclusions which appear to be justified from the data put on record
above can conveniently be stated as follows:—

           (1) One attack of spirillum fever in the monkey protects from a second in-
fection. This immunity, however, lasts only for a short period of
time. Monkeys from which the spleen has been removed shortly
after the crisis of an attack are also immune to a second infection
for at least a short period of time.

           (2) In the blood and lymph both of highly immunized monkeys and of
monkeys recently recovered from an attack of spirillum fever, anti-
bacterial substances are present and can be demonstrated both in
vivo and in vitro.

           (3) The blood plasma of a highly immunized animal confers protection on
a spleenless monkey when inoculated at the same time as the
spirillum material.

           (4) Fresh monkeys from which the spleen has been previously removed
may pass through an ordinary attack of spirillum fever, ending in
recovery by crisis and complete disappearance of the spirilla from
the blood.

      From these facts it would, therefore, appear certain that there must be some
relation between the production of anti-bacterial substances and the production.