3. Possible physiological explanation in the traction on the 

 tube feat resulting frora the movement of the rays over th 

 substrata. 



a, Application of this to Uangold*s starfish, to the right- 

 ing starfish and to the deviating tarfish. 



b. Svidenoe that the traction of the substrate does orient 

 the tubo feet. 



1. Direct evidence inconclusive. 



2. evidence from neurotoiaized animals* 



5. Evidence from the behavior of the animal when its parts 



are placed on separate substrates. 

 4* Evidence from the deviation reaction. 



1. Deviation reaction not interfered -.vith by cutting nervous 

 connections *ith int^r-radial area. 



2. Deviation reaction not elicited by prodding inter- 

 red ial area, 



3. Quantitative aspects of the "deviation rush* with 

 different weights on the animal vary irith mechanical 

 conditions while quantitative aspects of stimuli re- 

 quired to initiate the negative reaction do not* 



4. Operation of a tendency to return to original direction. 

 XI. Coordination of mov3mants of the tube fet with those of the 



arm as a whole* 

 1* Illustrations of the tendency of an arm to set itself more 



nearly at right angles to its actively oriented tubo feet, 



when such movements involve dorsal and ventral flexion and 



lateral twisting. 

 2. Ventral flexion of riid, of injured, and of nicotinized 



starfish* 



