56 AKT. 3. S. IKEDA : CONTRIBUTIONS 



Blastopore circle grown much smaller and become oval in 

 shape ; detached from the smaller left ex-ovate, although the 

 basal part of the horn by which it reached the latter still 

 remains ; approximated much closer to the larger right ex- 

 ovate ; dorsal lip again in the normal crescentic curve. 

 May 7, 9:14 a.m.: — (Fig. e). Blastopore just closed leaving a com- 

 paratively large yolk-plug to which the right ex-ovate is 

 attached. lieft ex-ovate found near the left margin of the 

 neural plate, though its distance from the right ex- ovate is 

 nearly the same. Neural plate clearly recognizable. 

 4:15 p.m. : — (Fig. /). Yolk-plug withdrawn into the interior. 

 Right ex-ovate attached to the posterior end of the right 

 medullary fold. Left ex-ovate in the same position as before. 

 Embryo itself normal, but its position greatly revolved left- 

 ward. 



In this egg, the blastopore was closed at the heavier right 

 puncture, and the growth over the yolk was undertaken mostly 

 by the ventral, and left lateral lips. As the axis of the embryo- 

 body has veered greatly leftward with the right ex-ovate as the 

 center, the main part of the body has been formed within the 

 early equatorial zone, as showm in Fig. 79. 



Egg No. 5. (Figs. 71 a-f, Fig. 80). 



May 5, .3:57 p.m. : — (Fig. a). Punctured at the approximate middle 

 point of the region antipodal to the fir.-t appearing dorsal 

 blastopore lip, at about the level of the equator. 



4:14 p.m. : — (Fig. b). Dorsal lip grown somewhat downward seems 

 to be moving leftward. 

 May C, 8:25 a.m. : — (Fig. c). Blastopore circle completed, and grown 

 moderately small ; ex-ovate attached within it near the ventral 

 lip. Area of the segmentation cavity diminished in size, and 

 has shifted its position opposite as usual to the blastopore circle. 



4:2G p.m.: — (Fig. d). Broad neural plate faintly recognized. 

 Blastopore greatly reduced in size ; ex-ovate attached to its left 

 margin. Area of the segmentation-cavity entirely vanished. 



