IV. i INITIAL STRUCTURE OF THE GERM 



219 



FIG. 127. Tlyanassa: cleavage of the egg after removal of the yolk- 

 be. 



. . vg e egg aer remova o e yo- 



lobe. a, f ; b, f ; c, first quartette formed ; cl, second quartette formed, 

 first quartette divided ; a-d, from above ; <?, from below : fourth quartette 

 formed ; /, ciliated embryo, from side. (After Crampton.) 



FIG. 128.- Patella : development of isolated micromeres. , J 

 micromere ; ft, c, first division ; d, ^ stage, with two trochoblasts 

 (stippled), one rosette-cell, and one primary cross-cell ; e, larva of 24 hours, 

 from the side, showing trochoblasts below, apical cells above. (After 

 Wilson.) 



