Plate V. 



Entire Eggs of C. plana ; one to four cells. 



All the figures on Plates V and VI were drawn at the stage level under Zeiss Apochromat 

 Obj. 3 mm., Occ. 4. 



Fig. 77. — Entire egg showing in optical action sperm nucleus and sphere approaching egg 

 nucleus, also accessory asters and yolk lobe. There is a single nucleolus in each germ nucleus. 



Fig. 78. — Contact of germ nuclei and fusion of spheres. 



Fig. 79. — Anaphase of first cleavage viewed from animal pole. The fused spheres lie above 

 the spindle and the polar bodies above the spheres. 



Fig. SO. — Early telophase of first cleavage, showing dual nuclei, equatorial constriction of 

 egg, yolk lobe and early bending of spindle axis. 



Fig. 81. — Late telophase of first cleavage, showing dual nuclei and extensive bending of 

 spindle axis. 



Fig. 82. — Two cell stage from animal pole ; spheres and centrosomes lie above nuclei. In 

 right blastomere centrosome has given rise to new initial spindle. 



Fig. 83. — Early prophase of second cleavage ; sphere remnants lie close to polar bodies ; 

 initial spindle at outer and upper side of nucleus in position of groove between the egg and sperm 

 halves. , 



Fig. 84. — Metaphase of second cleavage ; sphere remnants of first cleavage beneath polar 

 bodies ; spindles at outer sides of old nuclei ; outlines of the latter still preserved. 



Fig. 85. — Anaphase of second cleavage ; equatorial constriction beginning as a depression 

 beneath polar bodies ; the margins of this depression are raised into many pointed processes. 



Fig. SG. — Late telophase of second cleavage ; bending of spindle axis shown by relative 

 positions, of mid-bodies, nuclei and centrosomes ; dual nuclei. 



Fig. 87. — Resting 4-cell stage ; spheres in the apical angles of the cells ; centrosomes not 

 visible. 



Fig. 88. — Prophase of the third cleavage ; sphere remnants as in preceding figure ; the 

 spindle axes lie in various directions in the different cells ; the nuclear outlines still indicated, also 

 the escape of nuclear sap into the spheres. 



