E. COLi: TISSUE INVASION 



ing pseudopodia. These pseudopodia are somewhat simi- 

 lar to those of E. histolytica being formed rapidly and 

 more or less explosively, and being at first free from 

 granules although not so clear and hyaline as those of 

 E. histolytica. In every case the entire contents of the 

 cyst emerged as a single amoeba. Excysted amoebae were 

 watched for more than 6 hours but no division stages 

 were observed. The newly hatched amoebae probably suc- 

 ceed in maintaining their position in the intestine against 

 the movement of peristalsis by clinging to the intestinal 

 mucosa wth their pseudopodia. The trophozoites occur in 

 the upper part of the colon where the contents are liquid 

 and the precystic stages and cysts further down where 

 the feces become firmer. 



Food. The food of E. coli consists of bacteria, yeast, 

 starch grains and other protozoa, and all sorts of debris 

 contained in the large intestine. It differs markedly from 

 E. histolytica in its failure to ingest red blood cells. 

 Lynch (1924a) has reported a case in which an amoeba 

 that formed an 8-nucleated cyst indistinguishable from 

 cysts of E. coli ingested red cells. Fecal material was 

 added to a medium of salt solution to which a small 

 amount of human blood had been added and placed in 

 a ''warm incubator." Two hours later the majority of 

 the amoebae from the bottom of the tube were found to 

 have ingested red cells. Amoebae from the same patient 

 at a later date failed to ingest red cells. 



Tissue invasion. There is some evidence that E. coli 

 under certain conditions may invade the tissues of the 

 intestinal wall. Brumpt (1926a) has gathered together 

 the scattered data available from reports on human be- 



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