ENTAMOEBA COLI 219 



No other observer has been able to repeat this observation, and though 

 it is clear that the cyst must liberate an eight-nucleate amoeba or eight 

 uninucleate small amoebae, this has not been conclusively demonstrated. 

 Kessel (1923a) believes that he has succeeded in infecting rats with E. coli. 



CULTIVATION. — Though several observers claim to have cultivated 

 E. coli on the surface of solid agar media in all cases the amoebae have proved 

 to be coprozoic organisms. Boeck and Drbohlav (1925) succeeded in 

 maintaining E. coli for three days in the medium devised for the culture 

 of E. histolytica. Drbohlav {I92bd) and Thomson, J. G. and Robertson 

 (1925) have been more successful and have kept strains growing for two 

 or three months. 



ABERRANT FORM OF E. COLL— Mention must be made of an amoeba 

 to which Kofoid and Swezy (1921, 1921a) have given the name 



"^^ 



Av 





1^. 



/■':'/ 



^.,/^'^' 



3 



Fig. 102. — Free and Encysted Forms of " Comicilrnania lajleuri'' (x 2,000). 

 (After Kofoid and Swezy, 1921, Slightly Eeduced.) 



1. Free form with characteristic nucleus and clear pseudopodium. 



2. Encysted form with eight nuclei and chromojihile ridge. 



3. Cyst producing first bud through the pore. 



Councilmania lafleuri (Fig. 102). It is claimed that this is a distinct 

 amoeba which has been confused hitherto with Entamoeba coli. It is 

 supposed to show in its free stage some of the characters of E. Jiistolytica, 

 such as activity, development of ectoplasm, formation of clear pseudo- 

 podia, ingestion of red blood-corpuscles, and other features which are 

 those of E. coli, as distinct nucleus, vacuolation, ingestion of bacteria. 



