TO THE EMBRYOLOGY OF AMPHrBIA. 23 



at 2:15 p.m., on the same (2nd) day, (May 12th). The right, 

 and left side views were respectively at 97 c and 277° ( = 97 + 180), 

 and the posterior view at 187° (=97 + 90) of the rotating dish. 

 In this case, the spot where the dorsal lip of the blastopore first 

 appeared was far below the egg-eqnator, being about 20° below 

 that line. By 5:25 p.m., on that day, the lip had travelled about 

 15° further downward and the edges of the blastopore hardly 

 extended to the lateral meridian of the egg (i.e. the meridian 

 90° from that of the dorsal lip at its first appearance). During 

 the night which was quite warm, a great progress was, however, 

 made, and when observed next morning (the 3rd day or May 

 loth) the blastopore was completely encircled and the rotation 

 of the egg had begun. At 6:50 a.m., the egg was resting, just 

 on the ventral lip of the blastopore, which was very much smaller 

 in diameter than (only about i) that of Egg C at the corre- 

 sponding stage. 



At 8:40 a.m., the resting point of the egg was found at a 

 certain distance ventrad of the ventral lip of the blastopore so that 

 the whole of it could be seen in the posterior view of the egg. 

 The position of the dorsal lip at the time was about 30° below r 

 the equator. 



During this day, I was able to look at the egg every hour 

 up to 5:30 p.m., and had thus the opportunity of observing the 

 actual closure of the blastopore under microscope, which event 

 took place at 4 p.m. The shape of the gradually diminishing 

 blastopore was always circular, while the yolk-plug ready to be 

 withdrawn into the interior was elongated a little dorso-ventrally. 

 Also, no doubt owing to the small size of the blastopore to start 

 with, its closure in this egg was finished sooner than the rotation 

 of the egg, which was continued after that event over an arc of 



