1923] Kofoid^Swezy-Kessel: On the Genus Coun^'ilmania 439 



In specimens stained with iron haematoxylin the nuclear structure 

 of C. muris is distinctive. The nuclear membrane is very thin and 

 is seldom, if ever, encrusted with chromatin granules. The karyosome 

 is characterized by the mass of 5 to 8 dispersed granules, arranged 

 centrally or .subcentrally. This diffuse condition of the karyosome is 

 characteristic of every cyst in a resting phase encountered in this 

 species (fig. 12). 



A glycogen mass is commonly found in the 1-, 2-, and 4-nucleate 

 cysts (figs. 15-17). In these stages, phases of mitosis are usually 

 present. Mitosis is similar in this species to the process in other 

 species of parasitic amoebae in that the nuclear membrane remains 

 intact during division and that an intradesmose connects the centro- 

 somes of the spindle. The number of chromosomes found in C. muris 

 is six (fig. 11). 



The 8-nucleate cj'st is the typical or characteristic cyst of this 

 species. The nuclei in the resting stage are characterized by a very 

 thin nuclear membrane, often very difficult to find, its position being 

 determined by the limits of the cytoplasm surrounding the nucleus. 

 The karyosome retains the typical dispersed condition found in the 

 nucleus of the motile forms. 



The average diameter of the nuclei in the two-nucleate cysts of 

 this species is 5.5 microns, the range being 5 to 6 microns ; of the 4- 

 nucleate cysts the average diameter of the nuclei is 4.8 microns, the 

 range being 4 to 5.2 microns ; while in the 8-nucleate cysts the average 

 diameter of the nuclei is 3.4 microns, the range being from 2.75 to 3.75 

 microns. 



Chromophile ridges are commonly present in the 8-nucleate cysts 

 in this species (fig. 12). The chromatoidal bodies are typically 

 bundles of splinters with jagged ends (figs. 10, 13). In the 8-nucleate 

 cyst the point of the chromatoidal body is generally foimd. in the 

 region of the pore. Budding occurs in this species in a manner 

 similar to the type of budding found in C. lafleuri (fig. 13). 



The cysts vary from 14 microns to 19 microns in diameter, with 

 an average of 15.8 microns. It occurs in both mice and rats of our 

 culture colony. 



COUNCILMANIA DECUMANI (RuDOVSKY) KeSSEL 



The motile forms of C. decuniani are very similar to the motile 

 forms of C. muris in that the vaeuolation and food materials are 

 identical and the pseudopodia are broadly rounded and hyaline in 

 structure. There is also no marked difference in size. 



