DIFFERENTIAL DIAGNOSIS OF THE DYSENTERIES 209 



onas will ingest and digest erythrocytes. In the discussion that has 

 arisen over the interpretation of this, there has been a tendency 

 on the part of some writers to miss the point which, to my mind, 

 is of great importance — tJiat the triclwnionads digest the cor- 

 puscles. The general run of trichomonads are vegetarians and the 

 fact that certain of them can digest and assimilate animal food I 

 have interpreted (1920) as possibly indicating a trend of evolution 

 towards obligatory tissue parasitism. It is quite true, as Hegner 

 (1928) and others say, that the mere ingestion of er}1;hrocytes 

 is not proof of pathogenicity. In all cases where I have observed 

 it, the symptoms clearly were caused by agents other than the 

 flagellates. The liver abscess in Kessel's case undoubtedly was of 

 amoebic origin. 



While I believe that the case against the intestinal flagellates in- 

 cluding those of the trichomonad group has been grossly over- 

 stated by many writers, still, more definite evidence must be 

 developed before we are justified in ignoring them entirely as 

 possibly contributing to confusion in the diagnosis of dysentery. 

 For myself, I can only say that I have seen many hundreds of 

 heavy trichomonad infections and never yet have found reason for 

 suspecting them as a cause of dysentery. In the instances in which 

 I have observed them to ingest erythrocytes, the corpuscles, as I 

 have stated, clearly ha\'e been the accompaniment of a typical 

 dysentery. 



Many writers credit Giardia with pathogenicity. Disturbances 

 attributed to the activities of this organism range all the way from 

 frank dysentery to simple diarrhea. It has been suggested that 

 the end-products of its metabolism are absorbed by the intestinal 

 villi and produce undesirable symptoms. Other suggestions are 

 that its close application to the intestinal epithelium may retard 

 normal absorption or provoke diarrhea as a response to irritation. 

 Definite evidence of any of these assertions remains to be de- 

 veloped. If any of these conditions can be shown to be caused by 

 Giardia, methods for the dififerential diagnosis of them apart from 

 other intestinal disturbances will have to be devised. 



There is even less evidence against Chilomastix, Entcroinonas 

 and Enihado]]ionas. Being less widely known among medical prac- 

 titioners they have enjoyed comparative immunity from implica- 

 tion in obscure intestinal conditions. Entania'ba coli, Endolimax 

 nana, lodania^ba biitschlii and Dientaina^ha fragilis are so dearly 



