no 



VII. 



GENUS lOD AMOEBA NOV. GEN. 



Up to the present only a single species belonging to this new genus 

 is known. This is the form which I shall call : 



lODAMOEBA BUTSCHLII PROWAZEK, 191 2 {EMEND.). 



Entamoeba biitschlii Prowazek, 19 12. 



? Entamoeba tetragena Hartmann, 1912 (pro parte). 



? Entamoeba coli Werner, 1912 {pro parte). 



? Valilkampfia sp. Chatton & Lalung-Bonnaire, 191 2 (pro parte). 



? " Free-living amoebae" James, 1914 (pro parte). 



"Spherical bodies," Wenyon, 1915. 



" Iodine cysts " or " I. cysts," Wenyon, 1916. 



" I. cysts," Wenyon & O'Connor, 1917. 



" Joodcysten," Brug, 1917. 



" Pseudoiimax," Kuenen & Swellengrebel, 191 7. 



Entamoeba tetragena Flu, 1918 (pro parte). 



Endolimax Williamsi Brug, 1919 {nee Prowazek, 191 1). 



History and Nomenclature. 



The first recognizable account of this amoeba seems to me to be 

 that of Prowazek (191 2 a), who named it Entamoeba butschlii — at the 

 same time noting that " the designation Entamoeba is provisional, 

 since we do not know the life-cycle." His description is very imperfect. 

 He saw but a single infection, in a child from the Caroline Islands in 

 Saipan (Ladrones). The case was also infected with E. coli and other 

 organisms. 



Prowazek states that his amoebae measure 10-24 H' (presumably in 

 diameter, when rounded), and that their nuclei are vesicular, with a 

 round central karyosome containing a centriole. Between the karyosome 

 and the membrane there is a network with chromatin granules dis- 

 tributed on it. " Cyclical processes " are observable around the karyo- 

 some, and stages in "nuclear division" are described. "Division" 

 stages with two and three nuclei are figured. The cyst is also figured, 

 but not described. It is merely said to be round, with a distinct 

 membrane, and entirely different from that of E. coli. The specimen 

 figured is said to have measured i4'8 fi. It is uninucleate, with its 

 protoplasm apparently shrivelled. 



Hartmann (1912) has figured an organism which he calls a "young 

 amoeba " of Entamoeba tetragena (his fig. 2 a, b), and two other 

 organisms — described as "degenerate forms" of the same species (his 

 figs. 15, 16) — which appear to me to be probably the form under dis- 

 cussion. They certainly do not look like E. histolytica, at all events. 



