not reached the base. The s 

 avity ' s . c . ) recalls that of Fig. 15. Let 



. ire the next, Mo. 22 , which is a view 

 similaj - -celled stage, 



.sax cells rusting on the yolk, six in 



of 

 the whole enclosing a spacious itation cavity, 



.ion cavity f s.c .J ex" 

 . i g. . ... be given as 



a section - . ssin 



keystone cell. The centra .as not yet cc cut 



itself off from its m - cell to 



a resting nucleus curiousl; 

 There h« , ! 



: , such sixteen- eel 

 considered typical for i efish. Of these two are suf- 



ficient h ii... the usunx t s to be called noi 



but a great majority, fully ninety . - iose stu< L 



are like figures 18,13, and 20, PI, I, In this connect- 

 tion, Hertwig's stat .-. , pp. -S) wi reference 



to the fourth segmentation : sixti -cell- 



ed sta , i interest. says, "The end result is every- 



where the same, a 'checkerboard- ' arrangement of sixteen 



