AMCEB.E OF THE INTESTINAL TRACT. 193 



mceba tetragena, but I consider the evidence sufficient 

 to prove that this species is capable of causing dysen- 

 tery in susceptible animals. 



THE DIFFERENTIAL DIAGNOSIS OF ENTAMCEBA 

 COLL, ENTAMCEBA HISTOLYTICA,, AND ENTAMCEBA 

 TETRAGENA. As these species are most commonly 

 found in the human intestine it is important that one 

 be able to distinguish between them, especially be- 

 tween the pathogenic Entamaeba histolytica and 

 tetragena and the harmless Entamoeba coli. 



The differentiation of these parasites rests upon 

 the study of their morphology and of their methods 

 of reproduction. From a practical standpoint the 

 diagnosis must be made from the differences in the 

 appearance of the three species as they are observed 

 in the feces, and such a diagnosis can be made, pro- 

 vided one cares to spend the time necessary for this 

 purpose. I do not mean to infer that one who has 

 never studied amoeba? can differentiate between 

 species, but I firmly believe that anyone who has 

 thoroughly studied these organisms will be able to 

 distinguish species if sufficient material is available. 

 One has to have studied free-living forms of amoebae, 

 as well as the forms occurring in the feces of man and 

 other animals, to be able to easily differentiate species 

 and much of the confusion and inaccuracy which has 

 arisen in the classification and description of the para- 



