82 ART. 3. S. IKEDA I CONTRIBUTIONS 



The results of the above experiments by the puncture of eggs 

 may be summed up as follows : — 



1). When the puncture is single and is at or below the 

 level of the dorsal blastopore lip at its first appearance, the blasto- 

 pore always closes at the point of puncture. Group I., No. 5, 

 Group IL, No. 1, Group III., Nos. 1, 2, and 3 appear to be 

 exceptions to this general statement, but in these cases there were 

 disturbing conditions such as the detachment of the ex-ovate 

 formed, or the formation of unexpected accidental ex-ovates on 

 other parts of the egg-surface. 



2). When two or more punctures are made at the same 

 time on different parts of an egg, the blastopore closes at the one 

 which causes the greatest injury. In Eggs No. 4 of Groups I., 

 III., and IV., the right puncture was always the severer of the 

 two : hence the blastopore closed at that point, The egg of the 

 same number in Group IL, is only an apparent exception, for 

 an accidental ex-ovate had been produced near the ventral lip 

 which hindered its further growth. 



3). The extent to which various portions of the blastopore 

 lip grows is not constant in punctured eggs but depends entirely 

 on the position of the pierced point. When the blastopore arrives 

 in its downward growth at any injury, the portion of its lip which 

 touches the injury is hindered in its further course, and while 

 this portion is, so to speak, trying to get over the obstacle, the 

 other parts of the lip have time to grow over a larger extent 

 than is normal. If the obstacle is not serious (Group I., No. 5), 

 or is in some way detaehed (Group I., Nos. 4, 9, and 10, Group 

 III., No. 7), the hindered portion may get over it and grow 

 beyond, showing only more or less retardation. If the obstacle 

 si serious, the downward growth may be entirely stopped and 



