AMOEBAE OF THE INTESTINAL TRACT. 119 



The size of this parasite is of importance in diag- 

 nosis as there is no parasite which has been so fre- 

 quently mistaken for epithelial cells or for leucocytes 

 when in the non-motile condition. When moving the 

 organism is easily recognized, but when non-motile it 

 is most difficult to differentiate from other^ cells oc- 

 curring in the feces. In fact it has been stated by 

 some good observers that it is not safe to diagnose the 

 presence of amoebae in feces unless motility is ob- 

 served, but while this may be good advice for the 

 beginner, it is too general a statement, for if the 

 organisms are not undergoing degeneration they are 

 easily recognized even when non-motile by one who has 

 had experience in the study of this class of parasites. 



If it is remembered that these organisms are 

 larger, as a rule, than the leucocytes or intestinal 

 epithelial cells ; that they generally contain red blood 

 cells; and are divided into two distinct portions, an 

 ectoplasm and endoplasm; it should not be difficult 

 to differentiate them from other bodies occurring in 

 the feces. 



Shape. When resting, Entamoeba histolytica is 

 generally spherical in shape, although it is not un- 

 usual to observe oval organisms. When in motion 

 great variation in shape is observed, due to the pseu- 

 dopodia, so that it is impossible to accurately describe 

 the contour of the parasite at this time. 



