4 2 VETERINARY BACTERIOLOGY 



Immunity. No method of immunisation against the E. 

 histolytica has been developed. 



Bacteriological Diagnosis. The E. histolytica may be recog- 

 nized in the feces, and separated from the E. coli by its larger size, 

 its distinct differentiation into a hyaline refringent ectoplasm and a 

 more granular endoplasm, the presence of more than one vacuole 

 usually, the common presence of erythrocytes in the protoplasm 

 in the course of digestion, by the less prominent nucleus, and by 

 formation of spores by a process of budding with encystment. 



Entamceba tetragena 



Synonym. Entamccba africana. 



This species was first described by Viereck in dysentery in 

 Africa. Since that time the same organism has been noted by 

 Hartmann, Werner, and others. It has been found capable of 

 producing dysentery in cats. It resembles morphologically the 

 Entamceba coli more closely than the E. histolytica, but differs 

 by the formation of four spores instead of eight within the cysts. 



