1923] Kofokl^Swezy-Kessel: On the Genus CouncUmania 435 



We have found both species in both rats and mice of our laboratory 

 colonies, and refer them to the genus Councilmania because both bud 

 in the encysted stage, and have distributed karj-osomes, at least at 

 some stages. 



The following summary of the characteristics of the three known 

 species belonging to the genus CouncUmania will facilitate their 

 determination. 



Councilmania lafleuri Kofoid and Swezy 1921 



The motile amoeba is characterized by explosive thrusting out of 

 broadly rounded ectoplasmic pseudopodia, one, often two, less fre- 

 quently three at one time. In life these are absolutely clear and 

 hyaline and may linger unchanged for some time before the endo- 

 plasm moves in the same direction. They are often shorter and 

 broader than shown in figure 1. The line of separation between endo- 

 plasm and ectoplasm is sharply marked. The nucleus has in this 

 phase a well developed film of peripheral chromatin, which may 

 retract in scattered blobs, five to eight in optical section. Inside of 

 this is a zone traversed by granular radii, the outer part of which is 

 more granular and the inner forms a clearer halo about the ccntraUy 

 located karyoso'me. The karyosome is not solid and spherical but has 

 irregular margins indicating that it is an assemblage of granules. 

 These are more closely packed together in the motile stage than in 

 the cysts. The endoplasm contains food vacuoles with bacteria, the 

 ■ cysts of other protists, and, at times, red blood corpuscles. 



The cysts occur in the 1-, 2-, 4-, and 8-nucleate stages (figs. 2-5) 

 in the stools, but the earlier phases are best found in the liquid 

 stool after a saline purge. The glycogen vacuole is best seen in the 

 binucleate cyst (fig. 2) when it crowds the nuclei to the periphery'. 

 It may be single or multiple and may resist prolonged iodine staining 

 at times. It stains in sections in Best's carmine. As it disappears, 

 the chromatoidal bodies (fig. 2) form as flakes and splinters about 

 its periphery and in later phases concentrate in a centrally located 

 bundle (figs. 4, 5) with ragged or irregular ends. 



The nuclei of the earlier encysted stages often appear in pre- 

 mitotic phases. In some of these (fig. 2) eight chromosomes and a 

 meridional intradesmose can be demonstrated. The most typical 

 nuclei in the resting phases can be best seen in the 8-nucleate cysts 

 (figs. 4, 5). These are characterized by a slight amount of peripheral 

 chromatin (fig. 4), or none at all (fig. 5), and the intermediate zone 

 is often very clear so that the nuclei stand out in the cytoplasm as 



