viii, B. 4 Walker and Sellards: Entamoehic Dysentery 307 



dysentery; that is, a "contact carrier." And case 41 developed 

 entamoebic dysentery after ingesting Entamoeba histolytica that 

 had been passed through 2 "contact carriers." The history of 

 this strain of Entamoeba histolytica is as follows. It was orig- 

 inally from the same convalescent carrier (man A) from whom 

 cases 2 and 30 were infected. Entamoeba histolytica, from this 

 "carrier" convalescent fifty-nine days, was ingested by man 29, 

 who became parasitized, but did not develop dysentery. Enta- 

 moeba histolytica from this "contact carrier," one hundred 

 twenty-one days after infection, was next ingested by man 36, 

 who likewise became parasitized, but did not develop dysentery. 

 Finally, Entamoeba histolytica from this second "contact car- 

 rier," one hundred thirty-four days after infection, was ingested 

 by man 41, who became parasitized with Entamoeba histolytica 

 and developed entamoebic dysentery after fifty-seven days. 

 Therefore, three hundred seventy-one days and the passage 

 through 2 "contact carriers" — who had not, and have not sub- 

 sequently, developed dysentery — separated this experimental 

 case from the spontaneous case of entamoebic dysentery, a gap 

 bridged by the innumerable and continuous generations of Enta- 

 moeba histolytica in 4 different men. 



No case of spontaneous entamoebic dysentery has occurred in 

 this ward during the period of these experiments with Enta- 

 moeba histolytica. 



Therefore, it is believed that the results of these experiments 

 warrant the conclusions that Entamoeba histolytica is a strict or 

 obligatory parasite, that it cannot be cultivated on Musgrave 

 and Clegg's or other ordinary culture media, and that this 

 entamoeba is the essential etiologic factor in endemic tropical 

 dysentery. 



PART V. APPLICATION OF THE RESULTS TO THE DIAGNOSIS, 

 TREATMENT, AND PROPHYLAXIS OF ENTAMCEBIC 

 DYSENTERY 



By Ernest Linwood Walker 



The information concerning the etiology and endemiology of 

 entamoebic dysentery and the morphology, biology, and para- 

 sitism of Entamoeba histolytica, which has been obtained in the 

 course of this experimental investigation, is believed to be of the 

 greatest value for the diagnosis, treatment, and prophylaxis of 

 this important tropical disease. 



The identification of the specific microorganism in the labo- 

 ratory constitutes the final word in diagnosis, upon which must 



