438 Charles R. Stockard 



My former results are in harmony with those recorded above 

 and all go to indicate that functional activity exerts no influence 

 over the rate of regeneration in Cassiopea. 



IV FORM REGULATION AND ARREST OF REGENERATIVE ACTIVITY 

 IN PIECES OF THE MEDUSA DISK 



Many experiments w^ere performed to test primarily whether 

 heteromorphosis occurs in the regeneration of disk tissue in Cas- 

 siopea. It was thought, for example, that narrow peripheral 

 strips might regenerate a heteromorphic border or periphery and 

 thus form two parallel lines of sense organs instead of regenerat- 

 ing a new center or an entire disc. No indication whatever of 

 heteromorphic regeneration was observed from strips or pieces 

 cut in various patterns. A most striking regulatory tendency 

 was, however, discovered in these pieces. 



Pieces of the disks of various shapes, V-shape, bias-cut strips 

 and equilateral triangles all regenerate new tissue from their cut 

 edges. Before the process of regeneration has proceeded far these 

 pieces begin to twist and bend in such a manner as to approach 

 as nearly as possible the circular disk shape of an entire medusa. 

 After the circular shape is attained the miniature disk pulsates 

 like an ordinary disk. The new regenerative growth which had 

 begun so vigorously suddenly ceases and only the tissue necessary 

 to cement the cut edges into the disc form is proliferated. If, 

 however, any of these pieces be prevented from assuming the cir- 

 cular disk-like shape the regeneration from the cut edges contin- 

 ues for some time forming a broad mass of new tissue. It is con- 

 ceivable, although it has not been observed, that the new tissue 

 might continue to grow until a disk was formed in which the old 

 piece would occupy an area comparable to its former position in 

 the original disk provided enough reserve substance was present 

 to make so extensive a growth possible. 



A long bias-cut strip of disk border (Fig. 4A) regenerates tissue 

 from its cut edge most rapidly at the wide end and gradually 

 slower as the narrow end is approached, being slowest at that 

 point. Such a strip when forced to maintain its linear shape 



