26 ART. 3. — S. IKEDA I CONTRIBUTIONS 



downward growth of the blastopore rim, although there is a 

 possibility that I may have mistaken the exact position of the 

 posterior view at the start. The dorsal lip of the blastopore in 

 this egg did not return to its first starting point, though the egg 

 rotated 5° or 6° further after the complete closure of the blastopore. 

 The embryonic body formed of this egg was entirely normal. 



Although observations on the later features of the blastopore 

 closure and the beginning of the egg-rotation are wanting, the 

 earlier phases observed in this egg clearly show that the blasto- 

 pore was closed, as in the former cases, by the equal down- 

 ward growth of the lips all around over the yolk-mass, until the 

 dorsal lip arrives at about 66° below the equator. The position 

 of the embryo also coincides in the main with that in the former 

 eggs, although somewhat swung out of the blastoporic meridian 

 in its posterior portion. The only difference is that the dorsal 

 blastoporic lip did not return to its starting point, which is to be 

 accounted for by the smaller amount of the egg-rotation. 



I shall add a few more details obtained from the study of Egg 

 G which unfortunately became unstable in the later stages through 

 the insufficient fixation of the cover-glass upon the mirror-surface. 

 In this egg, the dorsal lip of the blastopore appeared first at 

 5 p.m., on the second day at about 10° or 12° below the equator, 

 and had moved down to about 50° by 9:50 a.m., on the third day 

 by which time also the blastoporic- circle was completed. After- 

 wards, the whole edge of the blastopore moved further down, 

 until at 3:10 p.m., on the third day the circle arrived at about 

 66° below the equator. When seen at 5:30 p.m., from the left 

 side, the egg had rotated about 35°. At this time, the dorsal lip 

 of the blastopore was found at 32° or 33° below the equator, and 



