INTESTINAL AMCEB^. 175 



Entamoeba coli. This is considered by Schaudinn to be a harm- 

 less inhabitant of the intestines and its presence in the faeces is not 

 considered of importance. Musgrave and Clegg do not recognize a 

 distinction between a nonpathogenic and a pathogenic amoeba, but 

 consider that the presence of amoebae, in the absence of symptoms, is 

 to be explained by the nonestablishment of a satisfactory symbiosis 

 with some bacterium or other parasite. They state, that as a result of 

 extended observation, persons harboring amoebae will sooner or later 

 develop dysentery. As regards the morphological points of distinc- 

 tion, they state that even in pure cultures, descended from a single 

 amoeba, the same variations in size motility, etc., may be observed. 

 They also consider that amoebae having all the characteristics of the 

 harmless commensal may cause marked pathological change. Craig 

 claims that the E. coli cannot be cultivated and, that several years 

 since noting E. coli in stools of healthy persons, these persons have 

 remained free of any dysenteric symptoms. 



The only safe way in recognizing amoebae in stools is to note 

 amoeboid movement. The encysted amoebae can scarcely be differ- 

 entiated from many vegetable cells and especially from large phago- 

 cvtic cells, of probable endothelial origin. By the use of neutral red in 

 very dilute solution the granular endoplasm will be observed to take 

 up the brick-red stain. 



E. coli varies greatly in size (8 to 40/1). There is no well-marked 

 distinction between a granular interior and a more compact, hyaline 

 exterior. The nucleus is centrally situated, is distinct and on staining 

 with Wright's stain shows the chromatin coloration. It is sluggishly 

 motile and is of a grayish-white color. When stained it does not 

 show a distinction between endoplasm and ectosarc. The infecting 

 stage is an encysted form with 8 amcebulae. 



Entamceba histolytica. This is considered the pathogenic 

 amceba. Schaudinn considers that it is by the possession of its 

 tough, tenacious, glassy and highly refractile ectoplasm that it is able 

 to bore its way into the submucosa of the large intestine and bring 

 about those gelatinous like necroses, which, by undermining, even- 

 tually result in dysenteric ulcerations. 



It is also the species found in tropical liver abscess. As described 



