ENDOLIMAX NANA 109 



of them oftener. {Vide Dobell, Gettings, Jepps, and Stephen.;, 1918.) 

 Other series have shown comparable figures, — allowance being made for 

 the degree of thoroughness with which the examinations have been 

 carried out. There can thus be no doubt that E. nana is of frequent 

 occurrence in man. 



Pathogenicity. — Although most of the infections with E. nana iiitherto 

 recorded have been found in persons who have had intestinal ailments, 

 there is no reason to suppose that the organism is pathogenic. Wenyon 

 and O'Connor (1917) found it in the stools of healthy men, with no 

 history of dysentery or bowel trouble, and I can confirm their observations 

 in this respect. From such figures as are available I can find no appreci- 

 able difference in the frequency of infection with this amoeba in healthy 

 people and in those with intestinal disorders. Moreover, E. nana appears, 

 in its habits of Hfe, to resemble E. coll. It feeds chiefly upon bacteria in 

 the contents of the gut, and there is no evidence that it can injure the 

 tissues. It seems to me certain, therefore, that E. nana is a harmless 

 commensal, and not a pathogenic parasite. 



Treatment. — I may add here that no treatment has yet been found 

 which will remove an infection with E. nana. Emetine administered to 

 an infected individual — either hypodermically or /)6'r os — never removes 

 the organism permanently, though it may disappear temporarily from the 

 stools during treatment. I have now studied a large number of cases who 

 have received emetine treatment, and have seen no exception to the 

 general rule. No other substances — such as various intestinal antiseptics, 

 etc. — which have hitherto been tried, have any action upon the organism 

 in the human body. 



