22 ART. S. — S. IKEDA : CONTRIBUTIONS 



3). The arc passed by the egg in its rotation as a whole 

 around its horizontal axis is about 80°, because the final position 

 of the closed blastopore or the former yolk-pole never reaches 

 the equator and is about 10° below it. 



4). The rate of the egg-rotation in earlier stages is obviously 

 faster than the rate of the downward growth of the dorsal blasto- 

 pore lip. Gradually slowing, it becomes equal to the latter, at 

 about the time when the lip has returned to its first starting point. 

 Finally it becomes slower, before it entirely stops. 



5). As to the location of the embryonic body in the egg, 

 the main parts of it appear between the upper and lower poles of 

 the egg, along the meridian of the middle point in the dorsal lip 

 of the blastopore (the blastoporic meridian). The lower yolk-pole 

 corresjionds to the tail end, while the foremost point of the head 

 end is about 30°-35° from the upper pole. 



6). The initial vertical axis of the egg is at the end 

 brought nearly to concide with the antero-posterior axis of the 

 embryonic body, while the lateral axis of the egg remains strictly 

 unaltered. 



The egg-mass from which Egg H was taken, was deposited 

 early on the morning of May 11th. As the eggs were in the 

 first cleavage stage, I tried to fix an egg in haste in order to 

 determine, if possible, the relations of the plane of the first 

 cleavage to the future axis of the embryo. But the three eggs I 

 mounted one after another all showed abnormalities and in the 

 mean time the first cleavage processes were passed. I therefore 

 on the next morning fixed a new egg (Egg H) on the mirror 

 surface and made the following observations. 



The first appearance of the dorsal blastopore lip was noticed 



