62 ART. 3. — S. IKEDA : CONTRIBUTIONS 



first appearance of the dorsal lip, and the embryo is formed almost 

 entirely on the i^per hemisphere of the egg (Fig. 78). The 

 results are therefore identical with those of the es;«; of the cor- 

 responding number in Group IV. 



Egg No. 4. (Figs. 85 a-c, Fig. 85'). 



April 17, 2:30 + p.m. : — (Fig. a). Punctured on both sides of the dorsal 

 blastopore lip, slightly below its level and at equal distances 

 from it (as in Group IV., Egg No. 4, Fig. 70 a). Right 

 puncture heavier than left in this egg also, but the two 

 punctures further from the dorsal lip and from each other 

 than in that egg. Ex-ovate produced from the punctures in 

 profile in the posterior view and about 20° below the equator. 

 Another unexpected small and transverse ex-ovate formed 

 directly beneath the dorsal lip which, however, disappeared 

 next day. 



April 18, 2:30 p.m. : — (Fig. b). Right and left ex-ovates somewhat 

 nearer each other. Blastopore oval and closer to the right 

 (larger) ex-ovate. Main axis of the future embryo-body some- 

 what curved toward the right side. This state of things can 

 probably be explained by unequal growth of blastopore lips. 

 Punctures and ex-ovates must check the growth of the blasto- 

 pore lips, when they are reached in the downward growth. 

 In this case, the growth has not entirely ceased but been 

 only retarded, longer on the right side than on the left, 

 because the injury was severer on the former side. Dorsal lip 

 was also somehow checked in its further downward growth, 

 when it reached the level of the ex-ovates, and overgrowth 

 must have been done mostly by the ventral lip. Hence the 

 position of the blastopore at the level of the ex-ovates ; its 

 shape is transversely oval, because retarded at the ex-ovates; 

 it is nearer the right ex-ovate because the left lip was, so to 

 speak, released sooner at the left ex-ovate and had grown 

 more than the right. 



April 19, 2:30 p.m. : — (Fig. c). Blastopore nearly closed, leaving only a 

 small yolk-plug. Right ex-ovate detached from the punctured 



