322 The Philippine Journal of Science ms 



lytica, the entamoebas were found 664 times, or in 71.39 per cent 

 of these examinations. The majority of these examinations were 

 of "carriers" who showed no dysenteric symptoms, but who were 

 passing the encysted entamoebse, often in enormous numbers, in 

 their formed stools. These encysted entamrebae, while incapable 

 of multiplication or other vital activities outside of the body of, 

 their host, are resistant to external influences and are conse- 

 quently capable of maintaining their vitality for some time 

 outside of the body and of passing uninjured through the stomach 

 of their host. Observations on the resistance of the encysted 

 stage of Entamoeba histolytica have not been as numerous in 

 these experiments as could be desired. However, experiments 

 were made with the cysts of Entamoeba histolytica kept two days 

 and with cysts of Entamoeba coli kept ten days at tropical tem- 

 perature. In both cases the cysts were kept moist. Parasitiza- 

 tion was obtained in every case with this material. Darling 

 (1913) put faeces containing cysts of Entamoeba histolytica in 

 10 volumes of sterile tap water for three days. He was unable 

 to infect 2 kittens or to find any cysts of the entamoebse after 

 this treatment, and concluded that the cysts disappear when in 

 contact with water for this length of time. I have no data on 

 the effect of drying upon the vitality of the cysts. Schaudinn 

 (1903), however, infected kittens with faeces containing Enta- 

 moeba histolytica air-dried for six weeks. On the other hand, 

 Darling (1913) failed to infect 2 kittens with faeces containing 

 cysts of this entamoeba that had been dried in air for seven 

 weeks. With regard to the resistance of the cysts of entamoebae 

 to the gastric juices in passage through the stomach, the follow- 

 ing data were secured in these experiments. Of 12 men who 

 ingested encysted Entamoeba coli without neutralizing the acidity 

 of the contents of their stomachs, 11 became parasitized; and of 

 6 men who ingested encysted Entamoeba histolytica under similar 

 conditions, all become parasitized. 



The knowledge of the part which these "carriers" of Entamoeba 

 histolytica probably play in the spread of entamoebic dysentery, 

 together with the ease and certainty with which such "carriers" 

 can be detected by microscopic examination of their stools, makes 

 the prophylaxis of this 'disease relatively simple. It is believed 

 that it would be possible, were it practicable, to eradicate this 

 disease from any region by a systematic examination of stools 

 and the treatment or isolation of all persons found to be carriers 

 of Entamoeba histolytica. In the absence of such thoroughgoing 

 prophylactic measures, a sanitary disposal of all faecal matter 

 should be insisted upon and household "carriers" of Entamoeba 



