TJir Bfhavior of Loxophvllini 



411 



that accompany these movements which have been previously 

 described. Soon, apparently as a result of these stretching out 

 movements that accompany its swimming forward, the piece began 

 to acquire a more narrow and elongated form. With each for- 

 ward motion the sides would be pushed around more toward 

 the middle of the cut end which gradually became reduced 

 in extent. With each movement ahead it could be seen that not 

 only the body elongated but that it elongated more on the oral 

 than the aboral side, causing it to bend toward the aboral side at 

 each advance. This bend is not the result of the contraction of 

 the aboral side, as one might very naturally suppose, but the exten- 



Fig. 2 Showing the regeneration of the posterior part of the body when cut off obliquely. 



sion of the oral side. Soon the oral side begins to grow longer 

 than the aboral and to become pushed around the anterior end 

 of the body. The striations which originally ran in a longitu- 

 dinal direction are now bent around the anterior end of the body 

 more on the oral side than on the aboral. There is no formation 

 of new tissue here, and no differentiation of new cilia on the cut 

 surface, but the oral margin becomes stretched around the anterior 

 end of the cut piece. Both sides of the body extend and contract, 

 the movements being greater toward the anterior end. This end 

 becomes (in consequence of these movements I) more narrowed 

 and more like that of the normal individual. The cut end of the 

 body is closed in by the gradual extension of the sides which fin- 



