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FIG. 63. Actinosphcenum eichhorni: first reduction-division, with ccntrosomes 

 (the stages here shown follow those of the centrosome-forrnation in Fig. 37). 

 A, Centrosome with radiations in a mass of archoplasm at one pole of the 

 nucleus ; B, two centrosomes and arclioplasniic cones, taking up positions 

 on opposite sides of the nucleus, in which chromosomes are beginning to appear ; 

 G, D, formation of the nuclear spindle and equatorial plate of chromosomes ; 

 E, division of the equatorial plate ; F, division of the nucleus beginning ; 

 G, H, division of the nucleus and rcconstitution of the daughter-nuclei ; one 

 daughter-nucleus will degenerate and be rejected as a reduction -nucleus ; 

 the beginning of this is seen in //, where* the upper darker daughter- nucleW 

 is the one which degenerates. After Hcrtwig (64). 



