No. 447.] HAMINEA SOLITARIA SA Y 



211 



which results in the complete envelopment of the 

 at an early stage. The third cleavage is dexiotropic (Figs. 11, 

 12, 13, 14). 



The time that intervenes between the formation of the second 

 and third quartettes of micromeres is the same as that for the 

 second and third cleavage. From this time on it was impracti- 

 cable to follow the further cleavage stages on the living egg. 

 Stained preparations confirmed the observations made on the 

 living egg. 



The second quartette of micromeres is formed by the fourth 

 cleavage which takes place in an anti-clockwise direction, the 



cells taking a position alternating with the cells of the first 

 quartette (Fig. 15). The next cells to undergo segmentation 

 are the first micromeres formed, segmentation takes place in a 

 la^otropic direction giving rise to the turret (trochoblast) cells 

 (Figs. 15, 16) ; immediately after, indications of division m the 

 second quartette of micromeres and the macromeres are evident. 

 The egg sketched shows eight complete spindles in the meta- 

 phase. The spindles occurring in the macromeres participate in 

 the formation of the last quartette of micromeres, the movement 

 being in a right handed spiral. Soon after the above described 



