SARCODINA 1065 



easier to find than in histolytica, and is distinctly outlined by a 

 heavy, double-contoured membrane. The nucleus, as in all amoeba, 

 is vesicular, and shows a small eccentric karyosome and dots of 

 chromatin on the nuclear membrane and imbedded in the nuclear 

 network. 



Multiplication in the vegetative stage is by binary fission of the 

 nucleus and the cytoplasm, resulting in two daughter cells. 



FIG. 128. ENTAMCEBA COLI. CYST showing a large vacuole. (Army Med. School 

 Collection, Washington, D. C.) 



Cyst Formation. This is characteristic of the species, and it 

 furnished one of the principal reasons for the separation of coli 

 and histolytica. Before encysting the animal frees itself of all 

 inclusions and becomes clear, transparent, and assumes a spherical 

 form, and secretes a cyst wall. The nucleus divides first into two, 

 then four, and finally eight daughter nuclei ; there is a large vacuole 

 containing glycogen which reaches its maximum size in the double 

 nucleus stage ; it later disappears and is not seen in the mature cyst. 

 Schaudinn described a complicated autogamy in the cyst, yet later 

 researches by Hartmann and Whitmore show nothing more than 



