438 



University of California Puhlications in Zoology [Vol. 20 



COUNCILMANIA MURIS (GrASSi) 



The motile forms of the amoebae belonging to the genus Council- 

 mania found in rats and mice cannot easily be distinguished in fresh 

 smears from the motile forms of C. lafleuri except by size. The aver- 

 age size of rounded motile C. decumani and C. muris is 19 microns 

 while C. lafleuri may attain a size of 63 by 35 microns. The pseudo- 

 podia are, without exception, hyaline in structure. This fact is borne 

 out by all the previous investigations of the amoebae of rats and 



Figs. 6 and 7. Councilmania lafleuri Kofoid and Swezy 1921. X 2500. From 

 camera lueida drawings of amoebae from smears of human faeces fixed in hot 

 Schaudinn's fluid and stained in iron haematoxylin. 



Fig. 6. Initial stage of emergence of bud. Tripartite chromophile strands 

 below \rith the pore at the tip of the upper one. The deeply stained cytoplasm 

 is beginning to emerge from the pore. The nuclei have centrally located, massed 

 or ring-shaped karyosomes. 



Fig. 7. Eight-nucleate cyst with broad, rather diffuse chromophile strand or 

 ridge (below). Note the depression at the surface. It is not a wrinkle of the 

 cyst wall but a cytoplasmic differentiation. The chromatoidal body is vertical, 

 is greatly reduced in size, and is enveloped in a clear zone. Its lower end points 

 toward the middle of the chromophile ridge. The nuclei are in early prophases 

 with small karyosomes on or near the membrane. The karyosomes are in most 

 instances divided and the intradesmose is in process of formation. When not 

 divided the karyosome at this stage of mitosis is usually peripheral in location. 



mice, namely, by Grassi (1881), Wenyon (1907), Brug (1919), and 

 Rudovsky (1921). For a detailed description of the amoeboid move- 

 ment of the amoebae, see Kessel (1923c). 



The normal habitat of this amoeba is the caecum, where it feeds 

 upon bacteria, yeasts, and on other Protozoa. So far as known, it is 

 non-pathogenic to the rat. 



