AMCEB^E OF THE INTESTINAL TRACT. 197 



Vacuoles and Contained Bodies. In Entamceba 

 histolytica a vacuole is always present, except in the 

 smallest individuals, and generally there is more than 

 one. This species also contains small oval bodies 

 representing the nuclei of the young spores, and gen- 

 erally one or more red blood cells in cases where the 

 feces contain blood. In Entamceba coli a vacuole is 

 generally absent and more than one of rare occur- 

 rence, while the oval bodies and red blood cells are 

 not observed. In Entamceba tetragena the vacuole 

 is frequently absent, although these bodies are more 

 often present in this species than in Entamceba coU. 

 This species may also contain red blood corpuscles 

 when they are present in the feces. 



Motility. In both Entamceba histolytica and 

 Entamceba tetragena motility is very marked, the 

 organisms progressing quite rapidly in a more or 

 less definite direction. Under the same circumstances 

 Entamceba coU is very sluggishly motile, while it is 

 almost never seen to progress in a definite direction. 

 This feature alone will serve to distinguish coli from 

 the pathogenic amoebae if the organisms are observed 

 in freshly voided feces, for it will invariably be found 

 that amoebae exhibiting marked motility will present 

 morphological features proving that they belong to 

 the pathogenic species. 



To recapitulate: if in a freshly voided specimen 



