290 ^^^ Philippine Journal of Science wis 



account for the several species of Entamoeba that have been 

 described by different observers in dysenteric stools. 



An attempt has been made to obtain experimental evidence 

 of the truth of these conclusions by the use in feeding experi- 

 ments of either motile entamoebae of the histolytica type or "tetra- 

 gena" cysts only. The material for these feeding experiments 

 was selected after a careful microscopic examination of both 

 fresh and stained preparations. 



Experiment 1. — Men 5 and 34 ingested motile and resting entamoebae 

 of the histolytica type only from a case of acute entamoebic dysentery. 

 Both men became parasitized, and "tetragena" cysts appeared in the formed 

 stools of these men on the fourth day after ingestion and have persisted 

 ever since. 



Experiment 2. — Man 2 ingested "tetragena" cysts from a convalescent 

 case of entamoebic dysentery. This man became parasitized, and "tetragena" 

 cysts appeared in his stools on the second day after the ingestion of the 

 entamoebae. These cysts persisted in the stools of this man until the 

 twentieth day, when acute dysentery developed with typical motile his- 

 tolytica only in his bloody mucous stools. The patient was given treatment, 

 and recovered from the attack of dysentery on the thirtieth day, when 

 "tetragena" cysts reappeared in his normal stools. On the sixtieth day 

 he suffered a relapse with motile histolytica only in his bloody mucous stools. 

 Treatment again relieved the dysenteric symptoms, but "tetragena" cysts 

 soon reappeared and have been found more or less constantly ever since in 

 his stools. 



Therefore, in these experiments it has been possible to obtain 

 (a) "tetragena" cysts in the stools of men fed motile histolytica 

 only, (6) motile histolytica in the stools of a man fed exclusively 

 with "tetragena" cysts, and (c) an alternation of motile histo- 

 lytica and "tetragena" cysts in the stools of a man having recur- 

 rent attack of entamoebic dysentery. The conclusions, therefore, 

 appear warranted that Entamcebd tetragena Viereck is identical 

 with Entamceba histolytica Schaudinn, that "tetragena" cysts 

 are produced in the life cycle of Entamoeba histolytica, and that 

 Entamceba minuta Elmassian is the preencysted stage of Enta- 

 moeba histolytica. 



Entamoeba histolytica Schaudinn (which includes "Entamoeba 

 tetragena" Viereck and "Entamoeba minuta" Elmassian) is 

 distinguished from Entamoeba coli, previously considered, by 

 a less refractive and more hyaline appearance; by a more 

 active motility; by an indistinct nucleus that is relatively poor 

 in chromatin; by cysts that are smaller and less refractive, 

 which usually contain one or more refractive bodies that stain 

 with chromatin stains and are designated by Hartmann (1912) 

 as "Chromidialkorper," and 4 instead of 8 nuclei; and by their 



