Regeneration in Cassiopea 



269 



came on June 17, and the second on July 16, twenty-nine days 

 later. Twelve days were allowed after the second operation. 

 In individual A about one-sixth of the margin was removed. 

 The regenerated margin was 2.c mm. in width twenty-nine days 

 later. It w^as then removed a second time and a similar segment 

 was removed from a part of the circumference which had not been 

 injured. Twelve days later the animal was killed and showed 

 a second regeneration width equal to 1.8 mm. and a first regenera- 

 tion width of 1.6 mm. 



^ 



B 



Fig. I 



Fig. 2 



Fig. I Outline of disk of Cassiopea xamachana in which segment B is a second regeneration and 

 segment A a first regeneration of the margin. 



Fig. 2 Outline of the disk of Cassiopea xamachana in which the unbroken line between B' and 

 lower A is a second regeneration of the margin to be compared with a first regeneration shown between 

 B and lower A. 



In individual B the character of the operation was the same as 

 in A but the removed portion of the margin was one-fourth of the 

 whole for each regeneration, and the regenerated margin was 2.7 

 mm. wide as compared with the uninjured 4.2 mm. In this case 

 the second regeneration width is 2.0 mm., and the first i.i mm. 

 The relative widths are shown in Fig. i, where A represents the 

 first regeneration and B the second. 



In individual C as shown in Fig. 2 in semidiagrammatic form 

 the original outer circumference is shown by the dotted line and 



