230 



JENNINGS AND JAMIESON. 



tion at one end of the body it would be natural to conclude that 

 the turning is due to them alone. 



1. The entire anterior disk, with the adoral cilia and the mouth, 

 was removed by a transverse cut near the anterior end (Fig. 3). 

 The posterior portion (b, Fig. 3), having only the body cilia, 

 swam through the water as usual, in a spiral, revolving from 

 right over to left. The aboral side in Stcntor ctendcus is usually 



curved in a very different manner 

 from the oral side, so that it is pos- 

 sible to distinguish the two sides 

 even when the disk is removed. 

 The specimen deprived of the disk 

 and anterior cilia reacted to me- 

 chanical and chemical stimuli by 

 backing and turning toward the 

 aboral side, just as does the unin- 

 jured specimen. 



After a time the specimen attach- 

 ed itself by the foot, and extended 

 in the usual manner. Currents, 

 due to the ciliary action, then 

 passed backward toward the foot, 

 or at times they were reversed, 

 passing in the opposite direction. 

 There was, however, no evident 

 FIG. 3. Stentor, cut transversely whirlpool formed, with a definite 



iust behind the disk. , \ j 



center, as in the uninjured speci- 

 men. The animal from which the disk had been removed, after 

 becoming attached, reacted to mechanical stimuli by turning into 

 a new position, and later by contracting, just as happens in the 

 uninjured specimen. (On the behavior of Stcntor, see Jennings, 

 1902.) 



2. The disk portion (Fig. 3, a), bearing the adoral cilia and the 

 mouth, also moved and reacted in the usual manner revolving 

 to the left as it swam, and responding to stimuli by backing and 

 turning toward the aboral side. 



3. Posterior one fourth comprising about one half the slen- 

 der "stalk" of Stcntor. This swims about, revolving to the 



