Experimental Studies on Germinal Localization. 213 



3/ ^32 ^33 



Fig. III. 



Development of Isolated ^s Micromeres. 



(Figs. 22-27 >^ 250; -Figs. 28-30 X 290) 



22, isolated micromere; 23. 24, first division; 25, 26, two different indi- 

 viduals, 32/8 stage, each with two trochoblasts, one rosette-cell, and one pri- 

 mary cross-cell; 27, an entire quadrant segmenting after removal from cal- 

 cium-free water, products of first and second quartets somewhat separated 

 from the basal (the first quartet group seen from the outside, the others from 

 the inside). 28, larva of 24 hours, from J/g-micromere, from the side, showing 

 trochoblasts below, apical cells above; 29, similar larva (with less regular pre- 

 trochal region), from below, showing both primary and secondary trocho- 

 blasts; 30, loose group, from J^-micromere, after 24 hours in water nearly 

 free from calcium, primary and secondary trochoblasts, apical cells, pre- 

 trochal ectoblast-cells; 31, group, with two apical cells, from ^-micromere. 

 after 24 hours in calcium-free water; 32-33, isolated apical cells from similar 

 culture. 



