1921] Kofoid-Swezy : Councilmani-a laflcuri 175 



cilmania and these figures of Dobell's to suggest the desirability of 

 verification of his interpretation that the free amoeba assigned by him 

 (his pi. 2, figs. 32-34) to his lodamoeba buetschlii really belongs to 

 that species rather than to Councilmania. Stools in which Council- 

 mania is not found but which carry the encysted stage of lodamoeba 

 should be searched for free amoebae. No "lodamoeba" has been found 

 in either free or in encysted stages in the cases from which our free 

 Councilmania have been derived. 



There is usually only a single nucleus in the free amoeba. We 

 have, however, found a number of amoebae with two nuclei each (pi. 19, 

 fig. 8) with the karyosomes in the skein stage. They do not appear 

 to be abnormal. In several instances in stools after prolonged treat- 

 ment with antimony trioxide amoebae have been found in which no 

 nucleus whatever can be detected. Many dead and abnormal amoebae 

 were present in these stools. 



THE ENCYSTED PHASES 



Plates 20-22, figures 11-28 



The precystic and encysted stages of this amoeba occur in non- 

 diarrheic stools predominantly, free stages being rare and usually 

 rounded up, moribund, and not reviving into activity on the warm 

 stage when taken from stools recently cooled. These uneneysted indi- 

 viduals represent either precystic individuals, those from the lower 

 parts of the bowel which have had insufficient time to pass into the 

 encysted phase, or more often moribund individuals, perhaps from 

 higher levels in the bowel which, by reason of senescence or other 

 physiological states, are not proceeding with encystment. The only 

 activity aroused in a few instances in these individuals on warming is 

 the slow protrusion or the withdrawal of broad shallow pseudopodia 

 one-third to one-half of the circumference in width. 



The precystic phases (pi. 19, figs. 6, 7) are uninucleate, rounded 

 up, with cytoplasm relatively free from food inclusions. The nucleus 

 does not as a rule differ from that in the free stage, has an enlarged, 

 often excentric karyosome with less evidence of a clear zone about it, 

 and considerable peripheral chromatin, and shows no indications of 

 approaching mitosis. 



The encysted stage, on the other hand, has a definite cyst wall, 

 generally exhibits eight nuclei, each with large, often asymmetrical 

 karyosome often centrally located, little peripheral chromatin, no 



