REGENERATION I29 



Yet neither part reconstitutes a complete mouth, even if either one 

 is completely removed. If the gullet is severed from the oral pouch 

 and the structures are left adjacent, or if the mouthparts are severely 

 injured in place, in the vast majority of cases the parts will rejoin 

 and perfect mouthparts be reconstituted without the formation 

 of a regeneration primordium. That some remodeling can occur 

 in situ was indicated by the fact that in one case an unusually long 

 and wide gullet was produced. In another case an eyelash was 

 thrust down the gullet and out the side of the cell yet no regenera- 

 tion followed and the stentor was later capable of forming food 

 vacuoles (Fig. 33B). 



Morgan also noted that some of his aboral, anterior fragments 

 formed a small oral pit at the proximal end of the membranellar 

 band remaining (Fig. 33c), and a similar effort toward oral re- 

 generation was also observed by Causin (193 1). I have observed 

 these formations too, as well as the tendency for the cut, proximal 

 end of the membranellar band to form at least a tight little coil (d). 

 I further reported (Tartar, 1956a) a case in which good mouthparts 

 were apparently reconstituted from the buccal pouch alone, as 

 well as the formation at least of an apparently complete gullet 

 instead of merely a pit at the end of an adoral band (Tartar, 1956b). 

 One may at least conclude that the mouthparts are quite capable 

 of repairing themselves. 



This may also be said for the membranellar band. If the band 

 is cut in two or small sections of it removed, the parts simply heal 

 together and no regeneration ensues. Whether some compensatory 

 growth of membranelles occurs if some are excised has not been 

 precisely determined. Stevens (1903) found in oral longitudinal 

 halves "some evidence" that the abbreviated membranellar band 

 increased in length. But the formation of regeneration primordia 

 in stentors from which half the band has been excised speaks 

 against the formation of membranelles in situ. Were this possible, 

 such regeneration would then not be necessar}^ 



In Prowazek's important if miscellaneous paper of 1904, he first 

 reported that the membranellar band in coeruleus is shed when the 

 ciliates are subjected to a weak solution of table salt. Then he noted 

 that after 24 hours a new membranellar band was regenerated in the 

 same place (an derselben Stelle). This is all he says. The point is 

 not developed further, nor was this remark italicized, as was his 



