REGENERATION 



109 



A 



C 



Fig. 26. Experiments concerning holdfast regeneration. 



A. Removal of posterior portion of primordium-site sector 

 is followed by temporary tail formation from cut ends of the 

 lateral striping; but the anteriorly located extension is later 

 resorbed in favor of holdfast reconstitution at original posterior 



pole. (After Weisz, 1951b.) 



B. Temporary tail-pole formation at suture may occur when 

 anterior is rotated on posterior half. Misaligned stripes do not 

 rejoin and projection occurs in oral meridian of anterior half, 



but is soon resorbed as stripe patterns interpenetrate. 



C. a: Sector with stage-3 regeneration primordium grafted 

 heteropolar into a non-differentiating host, b : Anlage is resorbed 

 and temporary pedal pole formation occurs from posterior end 

 of graft, c: Extra tail resorbed, graft patch diminished, and 

 specimen reorganizing doubly, d: Short, anterior primordium 

 contributes only a sector {x) of membranellar band, forming no 



mouthparts. 



