VIII, B, 4 Walker and Sellards: Entamcebic Dysentery 271 



constantly negative. This man was under observation for forty-three 

 days after the experiment began, when he was used for another feeding 

 experiment (experiment XVI). Altogether, he has been under observation 

 for two years and six months. During this time Amceba A has never 

 been found microscopically or culturally in his stools, nor has he ever shown 

 any symptoms of dysentery. 



Experiment XII. — Man 4, aged 34 years, had been under observation in 

 the prison one year and seven months. He had a negative dysenteric 

 history. He had been used for 2 experiments forty-one and twenty-nine 

 days previously, respectively, with negative results (experiments II and 

 IV). Physical examination of his abdomen and microscopic and cultural 

 examinations of his stools for amoeboid organisms were negative. He in- 

 gested the growth on 2 Petri-plate cultures of Amozha 7F, mixed with 

 magnesium oxide. Amceba_7F had been cultivated from a stool of a healthy 

 man. The cultures fed in this experiment contained only encysted amoebse. 

 Transplant cultures to test the viability of the cysts gave an abundant 

 growth of Amceba F. Following the ingestion, cultures of this man's 

 stools showed a growth of Amceba F on the second day only after feeding. 

 Microscopic examination of his stools for amoeboid organisms were con- 

 stantly negative. This man was under observation ten months after the 

 experiment began. No symptoms of dysentery developed. 



Experiment XIII. — Man 7, aged 30 years, had been under observation 

 in the prison for four years and five months. He had a history of 3 attacks 

 of dysentery, each of one week's duration, six years ago. He had been used 

 for a previous feeding experiment with negative results (experiment XI). 

 Physical examination of his abdomen and microscopic and cultural examina- 

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

 the growth on 2 Petri-plate cultures of Amoeba 9F cultivated from the 

 stool of a healthy man, mixed with magnesium oxide. The cultures 

 ingested by this man contained encysted amoebje only. Transplant cul- 

 tures made to test the viability of the cysts showed an abundant growth 

 of Aviceha F. Following the feeding, cultures of this man's stools on 

 Musgrave and Clegg's medium showed a growth of Amozba F on the first 

 day, but never subsequently. Microscopic examinations of his stools for 

 amoeboid organisms have been constantly negative. This man has been 

 under observation two years and six and one-half months since the experi- 

 ment began, but has never shown any dysenteric symptoms. 



Experiment XIV. — Man 1, aged 29 years, had been under observation 

 in the prison three years and ten months. He had a negative dysenteric 

 history, and had not been used for previous feeding experiments. Physical 

 examination of his abdomen and microscopic and cultural examinations of 

 his stools for amoeboid organisms were negative. He ingested the growth 

 on 3 agar-slant cultures of Amoeba lOG, mixed with magnesium oxide. 

 Amceba G had been cultivated from a diarrhceal stool in Kansas, United 

 States. The cultures ingested by this man were old, and contained en- 

 cysted forms exclusively. Transplants from each of the cultures fed, 

 made on fresh culture media to test the viability of the cysts, showed an 

 abundant growth of Amceba G. Following the feeding, Amceba G was 

 recovered in cultures of this man's stools on Musgrave and Clegg's medium 

 on the first and second days after feeding, but never subsequently. Micro- 

 scopic examinations of this man's stools were made daily, Sundays excepted, 

 for thirty-five days with negative results. On the thirty-fifth day his stool 



