270 



Charles Zeleny 



outer unbroken line between B and A. At the first operation the 

 half of the margin shown in the figure by the part to the right of a 

 line between A and A^ was removed. This was allowed to regen- 

 erate until it had a width of 3.5 mm. as compared with 4.5 mm. 

 in the uninjured margin. The second operation was then made 

 and consisted of a cut along the heavy line between B and B' 

 including five-sixths of the whole margin. This second operation 

 included a strip ofregenerated margin, and an equal strip of margin 

 which had previously been uninjured. After twelve days the animal 



Fig. 3 



Fig. 4 



Fig. 3 Regeneration of inner and outer margins in a non-pulsating individual of Cassiopea xama- 

 chana. Compare with Fig. 4. 



Fig. 4 Regeneration of inner and outer margins in a pulsating individual of Cassiopea xamachana. 

 Compare with Fig. 3. 



was killed and the average width of the second regeneration 

 [B' to lower A) was 1.4 mm. as compared with a first regenera- 

 tion width {B to lower A) of .8 mm. 



In all three individuals there is a well marked diflPerence between 

 the second and the first regeneration in favor of the former. The 

 character of the operation to a very large extent eliminates chance 

 of individual error, and makes the result reliable. The five 

 individuals of the other series strengthen the conclusion that in 

 Cassiopea a second regeneration of the margin occurs more rap- 

 idly than the first. 



