AMCEBJE OF THE INTESTINAL TRACT. 195 



know absolutely that the disease being treated as 

 amoebic dysentery is in reality due to Entamceba 

 histolytica, and that Entamceba coli has not been 

 mistaken for this organism." 



Since writing the above I have seen no reason for 

 changing my opinion regarding the importance of 

 differentiating the harmless from the pathogenic 

 amoebae, and I am convinced that scores of patients 

 have been treated weeks and even months for amoebic 

 dysentery when the only organism present was Enta- 

 mceba coli. 



It should be remembered that a differential diag- 

 nosis of these species does not rest upon the presence 

 of a single morphological feature but should only be 

 made after a careful consideration of all morpho- 

 logical data as well as the life cycle of the organisms 

 investigated. To illustrate: not every large, motile 

 amoeba, without a distinct nucleus, is Entamceba his- 

 tolytica, but if to these characteristics be added very 

 marked motility and a clearly differentiated and 

 highly refractile ectoplasm, we may rest assured that 

 we are dealing with Entamceba histolytica and not 

 Entamceba coli. Bearing in mind, then, that our 

 differential diagnosis must depend upon the presence 

 of several morphological features rather than one, the 

 following may be said to be the chief points in which 



