943 
cultures will sometimes produce infection when they are injected into 
the abdominal cavity. 
(b) If the subcultures are injected into the abdominal cavity of a 
monkey or guinea pig which six to sixty hours before that time has been 
inoculated with B. typhosus, then abscesses are much more likely to be 
formed in the omentum and elsewhere. In one series of experiments 
they were produced in four out of five monkeys. These infections are 
sometimes very extensive, many abscesses may occur in the omentum and 
also in the liver, spleen, abdominal wall and lungs. It is impossible long 
to continue these infections from animal to animal by employing sub- 
cultures, because after the first, or at most the second animal has been 
used, the amoebe present in the abscess will no longer grow on artificial 
media, even in symbiosis with the original B. typhosus. However, the 
infection may be continued through five successive animals by direct in- 
oculation of the abscess contents of one animal into the peritoneal cavity 
of the next one, the latter having previously been infected with B. 
typhosus. After the second or third animal has been injected, then the 
preliminary treatment of the monkey by inoculation with B. typhosus 
may be omitted, but the infection can then be continued through no more 
than two additional animals. We can not explain the failure to con- 
tinue this high parasitic type of infection by intraperitoneal injections 
any more than we can similar infections in the liver, but it is probably 
due to similar causes, which may be the inability of an organism which 
normally is saprophytic to continue an existence of absolute parasitism. 
INTRAVENOUS INFECTION. 
Infection occurred in one out of three monkeys which were inoculated 
intravenously with encysted mixed cultures of amceebe and B. typhosus, 
obtained from an experimental liver abscess. These monkeys had previ- 
ously been inoculated with B. typhosus alone. In the one positive result, 
the lesion consisted of two small amoebic abscesses in the lung and one, 
about 5 millimeters in diameter, in the spleen. We have already en- 
countered two cases of general infection in man. -However, in one of 
these the distribution was the same as that of an associated parasite, 
P. westermanti, and seemed to be due to a lymphatic rather than to a 
blood distribution. 
IMMUNITY. 
The influence upon the production of lesions by bacterial immunity 
possessed by animals against the symbiotic bacteria in amoebic cultures 
has not, as yet, received the attention the subject deserves. 
It may be recalled that it was brought out in our first publication that, 
whereas abscesses were produced in the livers of a certain percentage of 
monkeys by the direct inoculation of cultures of amoebe and Spr. cholera, 
that such an abscess did not occur in one monkey which had previously 
been immunized against that organism. It was furthermore noticed 
