274 2^^^ Philippine Journal of Science isis 



cultures made to test the viability of the cysts showed a good growth of 

 Amoeba H. Cultures of this man's stools showed a growth of Amceba H 

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

 scopic examinations of his stools were constantly negative. This man was 

 under observation one year four months and eighteen days after this ex- 

 periment began. No symptoms of dysentery developed. 



Experiment XX. — Man 10, aged 45 years, had been under observation 

 in the prison four years and eleven months. He gave a history of dysen- 

 tery three years ago. He had not been used for previous feeding experi- 

 ments. Physical examination of his abdomen disclosed thickened bands 

 along the sigmoid. Microscopic and cultural examinations of his stools 

 for amoeboid organisms were negative. He ingested the growth on 3 Petri- 

 plate cultures of Amosha 13F, mixed with magnesium oxide. This strain 

 of Amoeba F had been isolated in culture from a stool of an acute case of 

 entamoebic dysentery in Manila. The cultures of this amceba ingested by 

 this man contained encysted forms only. Transplant cultures made to 

 test the viability of the cysts showed a luxuriant growth of the amceba. 

 Am,ceba F was recovered in cultures from this man's stool from the first 

 to the third day after feeding, but never subsequently. Microscopic exam- 

 inations of his stools for amoeboid organisms were constantly negative. 

 This man was under observation five months after this experiment began. 

 No symptoms of dysentery developed. 



The protocols are summarized in Table I. 



From the protocols and Table I it will be seen that, with the 

 exception of species A and C, the specific amoeba ingested in 

 these experiments was in every case recovered in cultures on 

 Musgrave and Clegg's medium from the stools of the man to 

 whom they were fed on the first to the sixth day after ingestion, 

 but never subsequently. Species C was ingested only once, 

 and was not recovered in cultures. Three strains of species 

 A, fed five times, were never recovered in cultures of the stools 

 of the experimental men. 



On the other hand, microscopic examination of the stools of 

 these men were, with one apparent exception, always negative, 

 although in many of these experiments the men have been under 

 observation for over two years. The one exception to this 

 result was in experiment IX, in which the man was already 

 parasitized with Entamoeba coli before ingesting a culture of 

 Amoeba E. Amoeba E was recovered in cultures on the first 

 and second days after feeding and not subsequently, but it was 

 never found microscopically in the stools of this man. Enta- 

 moeba coli, on the other hand, was never obtained in cultures, 

 but it was constantly found microscopically in the stools of this 

 man. Thus Am^oeba E behaved like the other amoebse in the 

 intestinal tract of man, and it was distinguished morphologically 

 and biologically from Entamoeba coli in this experiment. 



