TO THE EMBRYOLOGY OF AMPHIBIA. 19 



29th), they had already united in a circle. The area enclosed by 

 them is circular in shape as may be seen in Fig. 24 which gives 

 a view of the lower half of the egg seen from below at 7 a.m. 

 The egg is resting upon the exact middle point of this area 

 (Figs. 26 and 27). The upper view of the egg is given in Fig. 

 25 which shows that the somewhat diminished but still large 

 area of the segmentation cavity is in the center and stands in 

 exact opposition to the blastoporic area of the lower view (Fig. 24). 

 Figs. 26 and 27 represent respectively the left, and right side 

 views of the egg at 8:10 a.m., on the same day : the dorsal and 

 ventral lips of the blastopore are exactly equidistant from the 

 standard line (the mirror-surface), showing that the rims of the 

 blastopore are growing over the yolk mass at the same rate of 

 progress all around its circumference. 



When seen at 9:43 a.m., on the same day, the egg was seen 

 to have rotated about 20° backward (Fig. 28, left side view) so 

 that instead of resting on the middle point of the blastoporic 

 area as heretofore, it was now resting nearly on the ventral lip 

 of the blastopore, and the dorsal lip had again moved slightly 

 upward. The area of the segmentation cavity at the upper pole 

 had also rotated slightly forward and kept its position exactly 

 opposite the blastoporic area of the lower pole. Both these areas 

 had now dwindled to about two-thirds of their original size. Note 

 on the right edge of the egg-outline the faintly marked embryonic 

 body stretching between these two areas. Figs. 29 and 30 give 

 respectively the lower, and upper views of the egg sketched fifteen 

 minutes later, and in them the eccentric position of the blastoporic 

 area, and of the area of the segmentation cavity is well brought out. 



At 11:27 a.m., on the same day, the dorsal lip of the blasto- 

 pore (Fig. 31, left side view) had moved upward greatly, and 



