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within the ameebic protoplasm. This observation is further borne out 
by the fact that in any culture the most active amcebe are found along 
the margins of the culture where the bacteria are also not so numerous. 
However, when the cultures are older, and in the more advanced 
portions of plate cultures which are two or three days old, where both 
amcebe and bacteria are more numerous and where many of the ameebe 
are older and the bacterial reproduction less active, we often do see 
amcebe containing bacterial bodies. Again, amoebee in culture may be 
made to take up red blood cells, granules, and foreign matter of various 
types. This phenomenon is most frequently to be seen in the type of 
old ameebe which has just been mentioned and, as with the bacteria, it 
seems to us that this process of engulfing visible matter is rather due to 
a lack of selectiveness shown by degenerating amcebe than to a type of 
assimilation connected with the nourishment of these protozoa. 
Ameebe, filled with bacteria and other foreign matter, may often be 
seen rapidly to disintegrate under the microscope, and before encysting 
they invariably extrude all of these foreign bodies. 
INTESTINAL SYMBIOSIS. 
(a) Saprophytic——There can be no reasonable doubt but that specific 
and definite symbiosis plays as great a part in the propagation and 
development of amcebe in the colon as it does in the test tube, and it is 
true that the intestinal symbiosis is a changing one due to frequent 
alteration in the bacterial flora of the bowel, just as it is in the altering 
bacterial growth in water or vegetable substances. The microdrganisms 
forming the intestinal flora during health are largely saprophytic, and in 
this respect the flora does not differ largely from that of other sources in 
which amoebe are found. 
Therefore, it would seem that the propagation of amcebe which reach 
the colon alive would depend largely upon whether satisfactory symbiosis 
could be found there or, in other words, whether there might be present 
in the bowel, at the time of the entrance of the ameebee, a sufficient 
number of bacteria similar to those forming the protozoan’s last extra- 
neous or test-tube symbiosis to continue its nourishment until it could 
adapt itself to the changed environment. Or again, there might be 
carried along with the amceba upon its entrance into the gastro-intestinal 
tube enough of its former intimate surroundings to allow rapid multi- 
plication to take place and to establish foci of its last symbiosis in the 
bowel, before destruction of the parasites could take place. 
It would seem that when a satisfactory symbiosis has been established 
in the bowel by either of the above methods and when amebw are prop- 
agating in the intestinal tract, their multiplication might continue 
indefinitely, and under certain conditions which we do not understand 
this condition might exist without any injury to the intestine. Just to 
what extent this actually occurs it is extremely difficult to determine. 
