BEHAVIOR 19 



Like those of other ciHates, stentor fragments which are not of 

 bizarre shape continue normal swimming behavior. Jennings and 

 Jamieson (1902) observed that isolated heads, tails, and mid-body 

 fragments of coeruleus rotate and spiral to the left. This indicates 

 that the direction of beating of the membranellar band during 

 swimming is not contradictory to the movement produced by the 

 body cilia, as well as that it is not the asymmetric oral structures 

 which produce the rotation. Rather, it is to be inferred that the 

 body cilia do not beat directly backward but obliquely, as Parducz 

 (1953) has elegantly demonstrated for Paramecium. Not only is 

 the direction of beating of each cilium oblique, the whole ciliation 

 is so coordinated that metachronal waves move slant-wise over 

 the surface of the cell, giving the appearance of rows of grain 

 moved in succession by the same gusts of wind. This apparently 

 calls for a wave-like impulse passing over the cell surface or the 

 successive '' firing " of adjacent ciUa down each ciliary row, as well 

 as coordination between adjoining rows. 



When a swimming stentor encounters a noxious stimulus it 

 swims backward a little, reversing the beat of the body cilia and 

 stopping the membranelles while pointing them forward, turns 

 toward the aboral side and swims forward again, quite as with 

 Paramecium (Fig. 2a). The membranelles then begin beating again 

 as they are pointed backwards presumably to aid in the forward 

 progression. Merton (1935) avers that the membranelles sometimes 

 help in swimming backwards but I find them always held quiet 

 then. He confirmed that posterior fragments can spiral forward 

 and also noted that they, too, are able to swim backward '' at will ". 



A common behaviour of stentors is to scoot over the bottom of 

 the dish with the oral surface apphed thereto, apparently to explore 

 for and break loose food particles like a vacuum cleaner. This is 

 the preferred method of feeding in the related genus Condylostoma. 



The effect of various chemicals in narcotizing and reversing the 

 ciliary beat, as well as cutting experiments concerning ciliary 

 coordination, will be considered in Chapter XIV. 



3. Avoiding reaction and learning 



After feeding, the next commonest response of stentors is to 

 manage to remove themselves from the reception of noxious 

 stimuli. Jennings (1902) made a careful and interesting study of 



