74 ART. 3. S. IKEDA : CONTRIBUTIONS 



blastopore on the ventral side. Neural groove, though not 

 neural folds, recognizable. At 7:00 a.m., fourth day (May 1), 

 embryo formation not advanced. Blastopore completely closed 

 at about the place of the exuded yolk-plug. 



This egg must somehow have been damaged by the puncturing 

 operation more than at first appeared. The final closing point of 

 the blastopore was not at the point of puncture, which was the 

 yolk-pole in this case, but at a point about 20° dorsad of that 

 pole on the blastopore meridian, and the incomplete embryo 

 stretched forward from that point. This is undoubtedly to be 

 accounted for in this way : the ex-ovate stood for a time in the 

 Avay of the growth of the ventral lip, but a greater obstacle in the 

 shape of a peculiar yolk-plug effectually stopped the downward 

 progress of the dorsal lip. Thus the ventral lip had time to over- 

 come its obstacle and to grow up toward the dorsal lip, where the 

 blastopore closed. 



Egg No. 2. 



Punctured about 20° below the dorsal blastopore lip in 

 the middle line (as in the corresponding number of the other 

 groups). Exudation little and injury seemed not very great. 

 Four hours later, dorsal lip grown down close to the ex- ovate. 

 Blastopore region somewhat bulged outward. At 8:23 a.m., 

 next day (April 29), a large new tubercle-like ex- ovate had 

 been produced hanging down from the dorsal region, in 

 front of the dorsal blastopore lip. Original ex-ovate now 

 attached to the middle basal part of the new tubercle, an- 

 teriorly from the dorsal lip. At 5:35 p.m., blastopore circle 

 completed but acuminate toward the tubercle, as also the area 

 of the segmentation-cavity from above. At 9 a.m., third day 

 (April 30), area of the segmentation cavity disappeared. 

 Blastopore area still large. At 5 p.m., blastopore greatly 

 reduced in size. Tubercle-like ex-ovate smaller and grown in 

 length, whereby the original ex-ovate was pushed further 



