atte Ne ee te en ee: ud -. See 7. pe eS 
941 
(e) In this connection it must be remembered that the conjunction of 
otherwise harmless bacteria, in close association with amcebee, may pos- 
sibly increase the virulence of the bacteria themselves. 
(f) Morphologically, the types of amoebe which will produce lesions in 
the intestine are not confined to those described as “H. histolytica ,;” 
indeed, they may as closely follow “/#. Coli,” and we must therefore 
conclude that, in so far as pathogenicity and non-pathogenicity are 
concerned, the species “H. coli” and “EH. histolytica” have not been 
established. 
LIVER INFECTIONS. 
The intestinal infection of man and animals surely represents the 
lowest type (often a mixed one) of the parasitism of amoebe, just as 
the lung infection represents the lowest order of parasitism of the tubercle 
bacillus, as has recently been pointed out by Theobald Smith in his 
classical article on the biology of the tubercle bacillus. As with the 
latter, the rhizopod here finds a nearer approach to its former saprophytic 
surroundings. For these reasons, consuinption is the most frequent type 
of tuberculosis, just as intestinal infection is the most frequent one of 
amoebiasis. In the case of the latter, this type of infection is the pre- 
cursor of almost, if not all of those in which a higher type of parasitism 
is manifested, and which is expressed in the form of liver and lung 
abscess ; abscesses in the brain and in other organs and in the occasional, 
errant, general infection of which we will shortly publish two cases. 
SUMMARY OF EXPERIMENTS ON INFECTIONS OF THE LIVER. 
(1) If monkeys are inoculated directly into the liver with mixed 
cultures of bacteria and amoebe, abscesses are produced in a certain per- 
centage of the cases. These abscesses may contain amcbe and bacteria 
in kind like the ones injected, or again only the amcebe may be present. 
Such abscesses are influenced somewhat by the type of bacteria in sym- 
biosis with the amcebe and in some instances only bacteria are found in 
the abscesses. 
When bacteria, which of themselves will not produce liver abscess, are 
used in symbiosis, then it is found that decided differences in the per- 
centage of abscesses produced with different amcebe occur, but the 
percentage of successful results with any given culture of amoebie may be 
increased by certain variations in the conditions. This is made evident 
by the following summary of our results. 
If ameebe are transplanted directly to culture media from an abscess 
produced in the manner just mentioned and then injected into the livers 
of other monkeys, abscesses in the latter are produced with greater 
certainty. An increase in virulence would therefore seem to be produced 
by this variation. Similar results are obtained by injecting the contents 
of the abscess from the first monkey directly into the liver of a second 
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