466 Charles R. Stockard 



condition than it would when four or five long arms are present 

 to be fed. Recognizing this, it might be possible for the speci- 

 mens regenerating four or five arms to increase in size so as to 

 equal those regenerating fewer arms and at the same time the larger 

 number of regenerating arms may have inhibited the increase in 

 size to a greater extent than did the fewer new arms. The actual 

 amount of new tissue formed is much more in the specimens grow- 

 ing the larger number of arms even though the rate of growth for 

 each arm is less. 



It seems then that the regenerating tissue in medusae and ophiu- 

 rans exerts a debilitating influence over the old body tissue in 

 consequence of an excessive power to absorb nutriment. This 

 excessive ability to appropriate nutriment seemingly possessed 

 by regenerating tissue is most significant and deserves careful 

 investigation. Experiments are now under way which I trust 

 may add something towards an analysis of this problem. 



VIII SUMMARY AND CONCLUSIONS 



1 Circular preparations made from the disks of the medusa 

 Cassiopea, regenerate tissue at equal rates whether in periodic 

 pulsation or in a condition of rest. Circular preparations in which 

 one-half pulsates and the other half is at rest regenerate tissue at 

 equal rates from the two halves. The halves are as near as pos- 

 sible identical, being equal portions of one individual still organ- 

 ically connected. Therefore, the process of regeneration in Cas- 

 siopea not only takes place independently of functional activity 

 but the rate of regeneration is also uninfluenced by such a factor. 



2 Peripheral pieces of the disk of Cassiopea cut in sundry 

 patterns, bias-strips, equilateral triangles and V's show decided 

 regulatory ability and tend to assume the original circular shape 

 of the entire disk in the most direct way that their forms will per- 

 mit. The attainment of a circular form either a disk or a cup- 

 shape inhibits the process of regeneration in the pieces, yet regen- 

 eration will continue for a much longer time if such shapes be 

 prevented. The factors here evinced are probably comparable 

 to those which coordinate the growth of tissues and organs in such 

 a manner as to insure the specific body form. 



