Regeneration in Cassiopea 



267 



the same surface as before. The measurements were made after 

 death. The animals were stupefied in CO, sea-water and pre- 

 served in 10 per cent formahn: 



TABLE I 



* Not strictly comparable with the others because the regenerating surface is at a deeper level. 



The average lengths of the regenerated arms are 1.66 mm. for 

 the individuals with one removed arm, 2.65 for those with two 

 removed arms, 3.24 for those with four, 3.17 for those with six, 

 2.40 for those with, eight and 2.45 for those with the whole mouth 

 apparatus removed. Since the individuals of a group are not 

 exactly alike, and since the amount of regeneration is dependent 

 on the size, the specific amount, /. ^., the regenerated length 

 divided by the disk diameter was obtained in each case. The 

 average specific amount of regeneration for each degree of injury 

 is given in Table I in italic type. It is seen that from a minimum 

 for the case with the lowest injury it increases to an optimum when 

 six arms are removed, beyond which it again decreases. Thus 

 with one removed arm the specific amount is .058, with two arms 

 removed it is .112, with four .144, with six .157, and with eight 



•117- 



A series of individuals with different extents of removed mar- 



