172 



Regeneration 



the body wall of a Cerianthus in such a way that 

 one side, a c, of the oblong is parallel to the longitudinal 

 axis of the animal, tentacles will grow on one of the 

 four sides only; namely, on the side ah.^ (Fig. 25.) 

 The other three free edges are not able to produce 

 tentacles. If an incision be made in the body wall of 



a 



Fig. 25 Fig. 26 



a Cerianthus, tentacles will grow on the lower edge of 

 the incision (Fig. 26). 



The writer tried whether or not by tying a ligature 

 around the middle of a piece of an Actinian this polarity 

 could be suppressed; but the experiments did not 

 succeed, inasmuch as the cells compressed by the liga- 

 ture died, and were liquefied through bacterial action so 

 that the pieces in front and behind the ligature fell 

 apart. It is therefore impossible to decide whether or 

 not a current or a flow of substances in a certain direc- 



' Loeb, J., "Untersuchungen zur physiologischen Morphologic der 

 Tiere." 



