94 



BIOLOGY OF THE PROTOZOA 



describes these as " reorganization bands," each band consisting of a 

 "reconstruction plane" (unstained) and a solution plane (Fig. 48). 

 Turner suggests that " The reorganization bands cause a phase reversal 

 of a colloidal system in which the chromatin changes from a continu- 

 ous (reticulum) to the dispersed (granular) phase." Certainly his 

 descriptions and figures indicate a marked change in the chromatin 

 after the "absorption bands" have passed by. A similar difference 

 is apparent in the chromatin granules anterior and posterior to the 

 nuclear cleft in Uroleptus halseyi, but here the portion with the 

 finer granules (reticulum?) is cast out. With this change in the 

 chromatin granules the macronucleus of Ewplotes is ready for 

 division. 





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Fig. -is. — Euplotes patella, macronucleus with "absorption bands" which start at 

 the two ends and progress to the middle where they meet. At division, two small 

 granules are discarded in the cytoplasm. (After Turner, from University of Cali- 

 fornia Publications in Zoology, 1930.) 



In another group of types we have to do with vesicular, endosome- 

 containing nuclei. The endosome may or may not contain an endo- 

 basal body. It is well represented by the nucleus of Spongomonas 

 splendida according to the observations of Hartmann and Chagas 

 (Fig. 49). Here, according to the description, the mass of chromatin 

 of the resting nucleus divides into two equal masses without frag- 

 mentation at any stage. Similar conditions are shown by the greg- 

 arine Gonospora varia according to Brasil (1905), by Sappinia dip- 

 loidea according to Hartmann and Xaegler (190S), by the simpler 

 amebaeand, in a striking way, by Haplosporidium ctenodrile according 

 to Granata (1915). 



In another group of types the chromatin of the resting vesicular 

 nucleus is contained also in a definite endosome, but, in preparation 



