VIII. B, 4 Walker and Sellards: Entamoebic Dysentery 323 



histolytica should be eliminated. Native household servants who 

 cook and handle food, who are usually more or less uncleanly in 

 their habits, and some of whom are carriers of Entamoeba his- 

 tolytica, are believed to be one of the chief sources of infection 

 of white persons residing in the Tropics ; and, as a most essential 

 prophylactic measure, stool examinations should be made of all 

 such servants, and those found infected should be discharged or 

 subjected to treatment. 



Equally important is the matter of personal prophylaxis. On 

 account of the relatively long incubation period of the disease 

 and the frequent occurrence of chronic and latent infections, it 

 will usually be possible to anticipate with treatment an attack of 

 dysentery. If persons residing in endemic regions should have 

 frequent stool examinations made by a competent protozoologist 

 and, if at any time parasitization with Entamoeba histolytica be 

 discovered, should undergo treatment, it is believed that it would 

 rarely be necessary for a person to suffer from entamoebic dys- , 

 entery. A stool examination made once a month would ordi- 

 narily be sufficient to anticipate an attack of dysentery. Such a 

 procedure would constitute a most efficient method of personal 

 prophylaxis. 



PART VI. SUMMARY AND CONCLUSIONS 

 By Ernest Linwood Walker 



This investigation was undertaken to determine experimen- 

 tally the etiologic relationship of different species of amoeboid 

 organisms to endemic tropical dysentery. It has consisted of 

 60 feeding experiments with the different species of Amoeba and 

 Entamoeba that have been implicated in the production of this 

 disease. 



These experiments differ from those hitherto performed (1) 

 in the number of comparative tests made of different species; 

 (2) in that the experiments have been more carefully controlled 

 and especially in that the species of amoeboid organism fed to, 

 and recovered from, the experimental animal in every case have 

 been determined; and (3) in the fact that the experiments have 

 been made not upon the lower animals but upon man. 



A. Twenty feedings of cultures, representing 13 strains and 8 species of 

 Amoeba, isolated from the Manila water supply and other nonpara- 

 sitic sources, from the stools of healthy persons or persons suffering 

 from diseases other than dysentery, and from dysenteric stools, 

 have been given to 10 different men, with the following results: 

 1. The Amcebie, when ingested by men, can usually be recovered in cul- 

 tures from their stools on Musgrave and Clegg's medium during the 

 first few days after feeding, but never subsequently. 



