260 The Philippine Journal of Science 1913 



These men were all Filipinos. There appears to exist no 

 definite evidence of a racial immunity of the Filipino to enta- 

 moebic dysentery. The disease is endemic in the Philippine 

 Islands, and many Filipinos sufi'er from it annually. Even 

 if it be granted that a certain degree of immunity does exist, it 

 is believed that the essential results of these experimental infec- 

 tions of Filipinos are applicable to all races of man. 



The condition of the men selected for the experiments, with 

 reference to previous attacks of dysentery and to present infec- 

 tions with amoeboid organisms, was determined by the clinical 

 history and physical examination of the men and by cultural and 

 microscopic examination of their stools. It was found neces- 

 sary to include some men who gave a definite history of a mucous 

 and bloody dysentery at some earlier period of their lives. While 

 there is no evidence of the existence of an appreciable immunity 

 following an attack of entamoebic dysentery, the possibility of 

 such a condition was controlled by feeding the same material to 

 other men who had negative dysenteric histories. It is interest- 

 ing to note in this connection that none of the men who had a 

 positive dysenteric history failed to become parasitized with the 

 pathogenic entamoeba. The clinical histories were supplemented 

 in most cases by physical examinations. In some of the later 

 experiments, in which men were used who had negative dysen- 

 teric histories, physical examinations were not made. In the 

 majority of the cases, records of one or more examinations of 

 the stools of the men for entamoebse were available in the hos- 

 pital records. Cultures on Musgrave and Clegg's medium and 

 microscopic examinations of the stools of all of the men, usually 

 before and after a purgative, were made for amoeboid organisms 

 before using them in these feeding experiments. Those men who 

 showed amoebae after either test, with certain intentional ex- 

 ceptions, were excluded. 



In order to cover all of the genera and species of amoeboid 

 organisms which were established by the morphological study 

 (Walker, 1911) and which might be concerned in the etiology of 

 entamoebic dysentery, a considerable variety of material has been 

 fed in these experiments. This included all of the species of 

 Amoeba that could be cultivated from the Manila water supply, 

 from a variety of other nonparasitic sources both within and out- 

 side of the Tropics, from the stools of healthy persons, and from 

 the stools of cases of entamoebic dysentery ; Entamoeba coli from 

 healthy persons and of persons suffering from diseases other than 



