rere 
932 
necessary for the life of the amoeba. The latter has become a true 
parasite and is living at the direct expense of its host. If an amoeba 
is grown with a bacterium such as B. -typhosus, which is capable of 
producing a bacterizmia in monkeys, and if such a culture is injected 
into a monkey two or three days after the animal has previously been 
infected with the same strain of B. typhosus, then we often obtain mul- 
tiple, localized abscesses, which are sometimes so extensive as to suggest 
a general infection. Often such abscesses will contain amcebe and 
B. typhosus, but at times only the rhizopodia will be found. Ameebe 
from such abscesses may usually be recultivated in symbiosis with B. 
typhosus. This, together with the necessity of a previous bacterial in- 
oculation of the animal, shows that notwithstanding the fact that the 
lesions which are produced are anatomically ameebic, bacteria are still 
playing a part, though a very indefinite one, in the symbiosis. 
If the contents of such abscesses as these are injected directly bs 
a second, healthy monkey, there may or may not be a single abscess at 
the place of injection but, contrary to the results of the first experiment, 
no extensive infection is observed; but if, as with the first, this second 
monkey has previously been given a typhoid bacteriamia, then the same 
far-reaching infection may result. However, there is one difference in 
the second monkey, namely, the presence of bacteria is much less evident, 
and it may be impossible to reclaim the amcebe by culture. In a third 
or fourth monkey, inoculated directly from the abscesses in the second or 
third, the previous bacterial inoculation may be dispensed with, and 
rather extensive infections, free from bacteria, may sometimes still be 
obtained. In other words, a true parasitism on the part of the amcebe 
has been established. 
Ges eee || Cen 
Such infections may be transmitted from animal to animal during’ 
two or three transfers, rarely through more. The amcebe can not be 
cultivated from these sources by using our present means any more than 
they can be from the bacterially sterile liver abscesses in man. 
The facts outlined in the above general statement of the building 
up of the pathogenicity of amoebe have been repeatedly verified by many 
and large series of experiments which seem to us to be conclusive. One 
series is given here and others will be found summarized in Chapter V: 
No, 1.—Monkey (M. cynomolgus) inoculated in the peritoneal cavity with a 
suspension of an encysted culture of amebe and the bacteria cultivated from 
eabbage. 
No, 2,—Monkey (M. cynomolgus) inoculated directly into the liver with part 
of the culture used in No, 1. 
After seven days both animals were killed. No. 1 was normal and No, 2 
showed an abscess of the liver, from which ameebe and bacteria were reclaimed 
by culture. 
No, 3.—Monkey (M. cynomolgus) inoculated in the abdominal cavity with an 
eneysted culture from the liver abscess of monkey No, 2. After seven days the 
animal was killed and found normal at autopsy. 
