52 ART. 3. S. IKED A I CONTRIBUTIONS 



divided into four groups, eacli of which consisted of ten eggs from 

 the same egg-mass. As I was most successful with the fourth 

 group, I shall begin with that : 



Fourth Group. (Figs. 67-84). 



This series of eggs was obtained from a mass probably de- 

 posited on the morning of May 4th. When taken on the morning 

 of May 5th, the eggs were near the end of the segmentation 

 process. At 2:20 p.m., of the same day, the first trace of the 

 dorsal blastopore lip appeared. Puncturing operations were com- 

 menced at 2:30 p.m., (i.e. 10 minutes after the first appearance of 

 the dorsal lip), and finished at 4:30 p.m. I will give my remarks 

 on each egg observed in the form of notes 1 * : — 



Egg No. 1. (Figs. 67 a-e, Fig. 76). 



May 5, 2:30 p.m. : — (Fig. a). Punctured just a little to the right of the 

 yolk-pole (as seen in the posterior view). 

 4:04 p.m. : — (Fig. b). Left side of the blastopore lip more inclined 

 downwards than the right, and the ex-ovate moved also slightly 

 to the right. Otherwise normal. (Fig. h). 



May 6, 7:55 a.m. : — (Fig. c). Ex-ovate attached to the right lip of the 

 now circular blastopore. Otherwise normal. 

 4:11 p.m. : — (Fig. à). Medullary folds and groove faintly recog- 

 nizable. Ex-ovate attached to the right margin of the now 

 very much smaller circular blastopore. 



May 7, 4:00 p.m. : — (Fig. c). Blastopore already closed. Medullary 

 groove ready to be closed by the closely approximated folds. 

 Embryo normal, except that the ex-ovate is at the right 

 margin of the posteriormost part of the medullary groove. 



This egg shows that an injury near or at the yolk pole causes 



perhaps the least amount of deviation from the normal course. 



1) The time given in the notes is in many cases only approximate within few minute.s 



