SEGMENTATION OF THE EGG OF BDELLOSrOMA STOUTI 



PLATE II 



Fig 1 3 Lateral view of germinal hillock m third cleavage stage. 



Fig' 14.' Polar viev. of blastodisc m third cleavage showing formation of micromeres. 



Fig 15 A blastodisc in approximately the same stage as the preceding. 



S: 16. Lateral view of germinal hillock in late third cleavage. Note that the hillock is reduced in 



height and broadened at base. It is now helmet-shaped. 

 Fig 17. Polar view of blastodisc showing irregular pattern of third cleavage. 

 Fig! 18. Blastodisc in third cleavage with central blastomere missing. 



Fig 19. Example of ""regular fourth cleavage. ,, . • c ecu xk;= fim.ro 



Fig 20 Typical blastodisc showing completion of fourth cleavage and beginning of fifth. This figure 



■ is drawn either from an unusually large egg or m greater magnification than the others. 

 Fig. 21. Typical example of fifth cleavage. 



Fig 22. Blastodisc in late fifth or beginning sixth cleavage. „ ■ , , , r, ,„^pnt of 



Rg. 23. Late segmentation showing retarded division (possibly abnormal) in the lower left segment of 



the blastoderm. . 



Fig. 24. Blastoderm in late cleavage showing intermingling of large and small micromeres. 



62 



