TO THE EMBRYOLOGY OF AMPHIBIA. 61 



and covered the posterior portion of the egg so that the 

 blastopore could not he seen. 

 April 19, 2:20 p.m.: — Head portion of the embryo seen beneath, and 

 in front of, the exuded matter. 



Although exact observation could not be made, there is no 



reason to suppose that the course of development was, in the 



main, otherwise than was seen in Group TV., Egg No. 2, or 



Nos. 6 and 7. 



Egg No. 3. 



April 17, 2:30 + p.m. : — Punctured as in Group IV., Egg No. 3, (Figs. 

 G9 a-f), but somewhat higher. Liquid-contnets forced out 

 of the segmentation cavity whose roof became shrunken. 

 Exudation, however, scon ceased, and the roof recovered its 

 usual appearance. Then the distance between the punctured 

 point and the dorsal lip became reduced to about J. This is 

 in all probability due to the upward movement of the 

 blastopore toward the punctured point as in Group IV., Egg 

 No. 3. 



April 18, 2:15 p.m. : — Area of the segmentation cavity and blastopore 

 area reduced in size in equal proportions. But the distance of 

 the ex-ovate from the dorsal lip remains the same. 



April 19, 2:30 p.m. : — General outline of the embryonic body evident. 

 Blastopore completely closed, and at the same distance from 

 it as before, the ex-ovate. 



How the ex-ovate keeps its distance from the dorsal lip 



unaltered, after the first rather sudden approximation of the two 



may probably be explained in this way. After the first pulling 



upward of the dorsal lip toward the injured point, it ceases 



to grow any further downward, due somehow to the injury 



inflicted above it and the consequent exudation of the contents 



within, and the overgrowth of the blastopore lips over the yolk 



is performed mostly by the ventral and lateral lips. The final 



point of the blastopore closure is therefore near the point of the 



