19-1] Kofoid-Swczy : Vouncilmania hiflvuri 179 



fashion. As the glycogen mass decreases in size and finally vanishes 

 they come to lie nearer the center of the cyst and may appear as a 

 central bundle visible in fresh smears as a more highly refractive area, 

 or in stained cysts as a fascicle of pointed splinters, or as scattered 

 threads, or even in the last stages as small spheroidal masses (pi. 21, 

 figs. 20, 22). 



The chromatoidal substance appeal's to be involved in the struc- 

 tural and metabolic processes which result in the formation of the 

 ridges, the opening of the pore, and the formation of the bud. This 

 is shown in some instances by the radiation of a tripartite ridge from 

 the end of the chromatoidal mass, or fascicle, nearest the cyst wall 

 (pi. 21, fig. 19), or by the formation of the pore and bud at the end 

 of the fascicle (pi. 22, fig. 23), and by the chromophile nature of the 

 ridge (pi. 21, figs. 17-21), of the material in the pore (pi. 22, fig. 27), 

 and of the young bud (pi. 22, figs. 23, 25, 27). 



The cysts of Councilmama are quite variable in contour and are 

 not predominantly spherical as in Endamoeha coli. In one hundred 

 cysts in a fresh stool examined in iodine-eosin stain, twenty-four were 

 spherical, forty spheroidal, twenty-two elongated or ellipsoidal, and 

 twelve asymmetrical. 



The cyst wall (pi. 20, figs. 12-16) is 0.8 to 1.5/t in thickness and 

 when fully formed is laminated and triple contoured. It consists in 

 optical section of a thin, outermost, sharp line, a middle, wide, clear 

 zone, and an innermost, dark brownish, granular zone nearest to the 

 cytoplasm. The clear zone is not always evident in the presumably 

 younger cysts. The cyst wall is generally thicker than in Endamoeba 

 coli. 



The structure of the nuclei in the cysts is extraordinarily variable 

 as a result of the prevalence of premitotic and postmitotic phases and 

 of the fact that the karyosome is relatively large, sometimes asymmet- 

 rical and centrally located or slightly or even decidedly excentric, and 

 somewhat subdivided. It often takes on a crescentic or reniform con- 

 tour and is rarelj' seen in the cysts in the form of a single central, or 

 excentric, spheroidal granule. In fresh stools, especially in those some 

 of whose cysts are budding, the karyosome may have the form of a 

 stout, reniform, or semicircular spireme with large chromomeres (pi. 

 21, figs. 17-22), or the chromomeres may be scattered throughout the 

 nucleus (pi. 21, fig. 18). 



The nuclear memhra^ne is very thin but distinct in iron haema- 

 toxjdin and is not heavily incrusted with peripheral chromatin in 



