Plate IV. 



Seco?id, Third and Fourth Cleavages of C. plana. 



Fig. 62. — Similar to preceding ; nucleus in early prophase. 



Fig. 63. — Section at right angles to preceding ; amphiaster for second cleavage present. 



Fig. 64. — Prophase of second cleavage. (Omitted from plate for lack of space and put in 

 text as fig. XVIII.) 



Fig. 65. — Metaphase of second cleavage. 



Fig. 66. — Anaphase of second cleavage ; chromosomes at the borders of the spheres ; 

 latter alveolar. 



Fig. 67. — Anaphase of second cleavage ; chromosomal vesicles apparently absorbing sub- 

 stance from spheres. 



Fig. 68. — -Telophase of second cleavage (horizontal section) ; centrosomes faintly granular. 



Fig. 69. — Rest stage at close of second cleavage ; centrosomes densely chromatic. 



Fig. TO. — Amphiasters for third cleavage moving out of spheres and old centrosomes; 

 nuclei show polar differentiation of the chromatin. 



Fig. 71. — Prophase of third cleavage ; nuclei indented ; sphere remnants at apical pole. 



Fig. 72. — Metaphase of third cleavage. 



Fig. 73. — Telophase of third cleavage. 



Fig. 74. — Resting stage after third cleavage. Centrosomes are reticular spindles. 



Fig. 75. — Same stage as preceding; section through one macromore showing the centro- 

 sorae, which becomes the amphiaster of the fourth cleavage, as a reticular spindle. 



Fig. 76. —Subdivision of the first quartette ; spindle in metaphase in one cell ; amphiaster 

 just escaped from the sphere in the other ; nucleus and spheres of the second quartette cells shown. 



