298 The Philippine Journal of Scierice im 



he had ingested a culture of Amoeba 5D. Result negative (part II, experi- 

 ment IX). Physical examination of his abdomen and cultural and micro- 

 scopic examinations of the stools for amoeboid organisms were negative at 

 the time of the present experiment. This man ingested motile Entamoeba 

 histolytica, strain C, mixed with magnesium oxide. Following the ingestion, 

 cultures of the stools of this man were negative for amoebae. Entamoeba 

 histolytica was found microscopically in his stools on the day following the 

 ingestion and has persisted in his stools ever since. This man was under 

 observation two months after the experiment began. No symptoms of 

 dysentery developed. 



Experiment LVI. — Man 35, aged 30 years, had been under observation 

 in the prison six years and nine months. He had a negative history for 

 dysentery, and had not been used for previous feeding experiments. Phys- 

 ical examination of his abdomen and cultural and microscopic examinations 

 of his stools for amoeboid organisms were negative. He ingested motile 

 Entamoeba histolytica, strain C, mixed with magnesium oxide. This man 

 has been under observation one year since the experiment began. Cultures 

 and microscopic examination of his stools have been constantly negative 

 for amoeboid organisms. He has consequently been reserved as a nonpara- 

 sitized control. This man has shown no dysenteric symptoms. 



ENTAMCEBA HISTOLYTICA, STRAIN D 



Strain D consisted of encysted entamoebas from a naturally 

 parasitized "contact carrier" of Entamoeba histolytica. This 

 woman had no history of entamoebic dysentery, but her stools 

 contained a moderate number of encysted Entamoeba histolytica. 

 This strain was used in 4 experiments, and there were no subse- 

 quent passages of it. 



Experiment LVII. — Man 37, aged 32 years, had been under observation 

 in the prison seven years and eight months. He had a history of an acute 

 dysentery four years previously. He had not been used for previous 

 experiments. Physical examination of his abdomen and microscopic and 

 cultural examinations of his stools for amoeboid organisms were negative. 

 He ingested cysts of Entamoeba histolytica, strain D, mixed with pow- 

 dered starch. Following the ingestion, cultures of the stools of man 37 

 were negative. Microscopic examination of his stools showed Entamoeba 

 histolytica on the eighth day after feeding. This man was under observa- 

 tion eight months and seventeen days after the experiment began. The 

 entamoebas have been found constantly in his stools, but no symptoms of 

 dysentery have developed. 



Experiment LVIII. — Man 38, aged 37 years, had been under observa- 

 tion in the prison six years and eight months. Dysenteric history was 

 negative, and he had not been used for previous experiments. No phys- 

 ical examination of his abdomen was made. Microscopic and cultural 

 examinations of his stools for amoeboid organisms were negative. He 

 ingested cysts of Entamoeba histolytica, strain D, mixed with powdered 

 starch. Cultures of the stools of man 38 following the ingestion were 

 negative. Microscopic examination of his stools showed Entamcsba his- 

 tolytica on the twenty-first day after the ingestion and more or less con- 

 stantly ever since. This man has been under observation one year since 

 the beginning of the experiment. No dysenteric symptoms have developed. 



