/ 16 aide of the aquarium no 



3h^th will. She tube feet at 



tretched out toward the wall, 

 tatfish still farther over 

 V__-- rays a e nexed dorsally and 



began migrating in their own direction. In the meantime the 

 coordination of the tube feot had spread so as to include all 

 the extended tuba feet in animal, which were soon all pointed 

 directly toward the wall of the aquarium* As the tube feet 

 became oriented in this direction, there was a coordinated 

 movement of the rays. Hay twisted to the left and bent over 

 toward the wall, ray & twisted to the right and bent over to 

 the wall and ray g bent directly over the disc toward the 

 wall, isacfli ray was seen to set itself more at right angles to 



Cnin^j^i^d 



the actively -extended tube feet whiOh had become coordinatedly 

 pointing toward the wall* 



As the rays a e continued their activity, the disc was 

 brought closer to the wall and with it, the other arms* As they 

 touted the wall, since the tube feet were oriented in the direo- 



tion of a e beaan executing the step reflex in this direction 

 and the animal started perfectly coordinated and normal locomotion 

 in the direction of ft e (the suspending thread having been out) 

 go rr elation oj these movements with the rj.ffrtinff reaction* 

 The *ove experiment is merely a simplification of the 

 righting reaction of the uncoordinated active Pisaster. If we 

 assume that two adjacent rays initiate the reaction by 

 attaching to the substrate with their ventral sides turned toward 

 each oth^r, the above description will fit the rioting reaction 

 with the change of only a few words. The same dorsal flexion 

 of the initating rays and their migration toward their tips will 



