lODAMOEBA BUTSCHLII 



"5 



inhabitant of the large bowel. /. bi'itschlii always dies very quickly 

 outside the intestine, and has not yet been cultivated. 



Nuclear "divisions" have been described by Prowazek (1912 a) in 

 /. bi'itschlii, but his figures are unconvincing. I have not been able to 

 study the division of this amoeba in detail, and the few apparently 

 dividing nuclei which I have seen are different from those described 

 by him. The usual method of multiplication is, no doubt, by simple 

 bipartition — as in most other amoebae ; but stages in the process are 

 extremely difficult to obtain. Binucleate amoebae, usually of large 

 size, are sometimes found ; and they probably represent forms which 

 have been arrested in division by discharge from the intestine — as in the 

 other species. A binucleate organism has been figured by Prowazek 

 (1912 a, PI. xviii, fig. 14), but I am not certain whether this figure was 

 really drawn from a free amoeba. The forms which I have seen usually 

 have two resting nuclei exactly like those of the active forms, with 

 central karyosomes : whereas his figure shows a form with nuclei like 

 those in the cysts. He states further that multiple division occurs, but 

 his figures are capable of a different interpretation {vide iitfra). I believe 

 there is no evidence of schizogony in this species. 



Text-fig. 2. — Outline drawings of cysts of /. iillschlii, in iodine solution. (Magnification 

 1,500 diameters.) 



Cysts. — The cysts of /. bi'ttschUi are very remarkable structures, 

 differing considerably from those of the other intestinal amoebae of 

 man. They have become familiar to many workers since Wenyon 

 first described them — as " I. cysts " — from the stools of dysenteric 

 patients from Gallipoli in 19 15. The living cysts may be nearly 

 spherical or oval, but they are very frequently irregular in outline. 

 They may be kidney-shaped, pear-shaped, fusiform, rhomboidal, or 

 almost triangular or square in outline, and their forms are often such 

 as almost to defy description. Text-fig. 2, A to O will give some idea 



