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PROTOZOOLOGY 



the stem to join the posterior band. According to Summers (1935) 

 a process similar to that of E. eurystomus occurs in Diophrys ap- 

 pendiculata and Stylonychia pustulata; but in Aspidisca lynceus 

 (Fig. 54) a reorganization band appears first near the middle region 

 of the macronucleus (6), divide into two and each moves toward an 

 end, leaving between them a greater chromatinic content of the 



Fig. 54. Macronuclear reorganization prior to division in Aspidisca 

 lynceus, X1400 (Summers), a, resting nucleus; b-i, successive stages in 

 reorganization process; j, a daughter macronucleus shortly after division. 



reticulum (c-i). Summers suggested that "the reorganization bands 

 are local regions of karyolysis and resynthesis of macronuclear 

 materials with the possibility of an elimination of physically or 

 possibly chemically modified nonstaining substances into the cyto- 

 plasm." 



The extrusion of a certain portion of the macronuclear material 

 during division has been observed in a number of species. In Urolep- 

 tus halseyi, Calkins actually noticed each of the eight macronuclei 



