-69- 



In general terms, the above interpretation is that the 

 orienftlted tube feet extend out in the direction of their orientation 

 and in this state are ready to give the step reflex upon contact stim- 

 ulation. In the absence of such contact stimulation there are reflex 

 connections between the myodermal sheath and the ambulaoral nervous 

 system of such a nature that the ray, by twisting or bending or both 

 sets itself more nearly at right angles to the actively oriented tube 

 feet. Fig. 18 illustrates the first movements of an animal inverted 

 during active locomotion toward a e. All of the extended tube feet 

 are protruded in the direction of the former anterior. Figs.. 19 aad 

 20 illustrate the movements of the arms as described already (p$ (, ) 

 wttch result in righting and in the ray assuming a position more nearly 

 at right angles with the oriented tube feet. During the righting pro- 

 cess the un stimulated tube feet remain extended toward the animal's 

 anterior. The rays a e. however, in accordance with the above princi- 

 ple, bend toward one another and down so that the tube feet come in 

 contact with the substrate, execute the step reflex and in the manner 

 outlined above initiate the righting. 



The tube feet, however, have been regarded (Romanes and Swart 

 (1881), Preyer (1886), Loeb (1900), Jennings (1907), Moore (1910^1910^) 

 Cole (1913* )) as taking hold of the substrate and pulling the animal 

 over. Observation of the reaction as it occurs on sand show that this 

 pulling is not a fundamental or necessary part of righting. Pulling 

 by oriented tube feet is, however, a part of the step reflex. Since 

 attachment increases with the resistance to the step (pp-<lft-), and th 

 resistance to the step, in the initiation of the righting reaction, is 

 very great, it follows that attachment is tight and pulling is the most 

 noticable activity of the tube feet. It is this pulling, that has ob- 

 scured the eyes of observers, the more important and fundamental thing, 

 of which this pulling is merely a part, namely the step reflex. 



