i8 



THE BIOLOGY OF STENTOR 



Fig. 2. Behavior of Stentor. 



A. Avoiding response : {a) normal swimming with left rotation 

 and slow spiraling; {b) contraction on adverse stimulation; {c) 

 backward movement even if stimulated at the base ; {d) turning 

 to aboral side with resumed forward swimming in new direction. 



B. Graded response of feeding animal to adverse stimuli: {a) 

 undisturbed posture ; {b) turning away ; {c) feeding vortex stopped 

 and beating of body cilia reversed; {d) sharp contraction; {e) 

 holdfast released and animal swims away, abandoning lorica {e) 

 if present. With repeated stimuli the response decreases in the 

 direction e-^a. (After Jennings, 1902). 



