Rate of Regeneration in Cassiopea xamachana. 



67 



Table i. — Regeneration from tlie cut periphery of the medusa-disk after removal 

 of circular strips of various width. 



Date 



June 13 

 June 13 

 June 19 

 June 21 

 June 23 

 June 25 

 June 27 

 June 30 

 July 

 July 

 July 

 July 



Jvly 



July 18 

 July 18 



Remarks. 



Exp. I Exp. 



Disk diameter before operation. 



Width of removed margin 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Disk diameter 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Disk diameter 



Width of new tissue 



86.7 



10 

 3-3 

 3-3 

 3-3 

 4-3 

 4-7 

 4-7 

 4-7 



51-5 

 5 

 5 

 5 



40.6 



5-1 



86.7 



10 

 3-3 

 3-3 

 3-3 

 4-7 

 5 



4-7 

 4-7 



45-5 

 4-5 

 4-5 

 5 



33-3 

 4-7 



Exp. 

 4- 



90 



28 

 4.2 

 4.2 

 Dead. 



Date. 



June 13 

 June 13 



June 19 

 June 21 



June 23 

 June 25 



June 27 



June 30 



July 3 



July 6 



July 6 



July 9 



July 12 



July 18 



July 18 



Remarks- 



Disk diameter before 



operation. 

 Width of removed 



margin. 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Disk diameter 



Width of new tissue 



Width of new tissue 



Width of new tissue 



Disk diameter 



Width of new tissue 



Exp. 4a. 



93-3 



Disk center 

 only re- 

 mained. 



6.7 

 6.7 



6.7 



5-3 



(thick) 4 



3 



3 



21 



4 



3-3 

 4.6 

 20 

 6.5 



Exp. 5. 



96.6 



Exp. 5a. 



77 



All of disk I Small strip of 

 removed. I disk tissue 



left. 



None j None 



None Regenerating 



from disk 



tissue. 

 None Same as on 



2ist. 

 None Film of tissue 



over entire 



I top- 



None ! Same as on 



25th. 



Exp 5* 



None.. 

 None. 



None. 



None., 

 Dead. 



As on 25th. 

 As on 25th. 



Same as ^17. 



None. 

 Regenerating 



from disk 



tissue. 

 Same. 



Almost same 

 as 5«. 



Same. 



As on 25th. 

 Dead. 



Thin film over top (aboral) 

 surface of mouth-arms, 

 regenerated from small 

 pieces of disk tissue. 



* Mouth-arms also removed. 



t Arched aborally, not measured. 



It was observed that those portions of the regenerating rim which were 

 touched or pressed against by the mouth-arms of the medusae regenerated 

 faster or grew out wider in a radial direction than the intermediate portions 

 which were not so pressed by the arms (fig. 2). This condition may pos- 

 sibly be due to the mechanical pressure of the mouth-arms against such 

 places causing them to thin or flatten out, thus giving a more rapid radial 

 growth, whereas the entire mass of tissue may be no greater here than from 

 other parts of the regenerating surface. I made no observations, however, 

 at the time of the experiments to ascertain whether the new tissue was thin- 



