44 * 



on the other, perhaps the stronger, aide. A this continues, 

 due to th comparative rigidity of the animal, there 10 a pull 



(h 1 ^ 



in the direction of the arrows (at the tips of the rays) to which 

 pull the tube feet seem to coordinate themselves. 



Direct pull, exerted throu^i the substrate by the movement 

 of the animal and acting on the tube feet, can,assuming that 

 it orients then, account for the above described behavior. We 

 nail now turn to the evidence for and against the contention 

 that the pull of the substrate does orient the tube feet* 



Direct evidence invoonsluBive. 



The obvious way of testing this is to slowlynpull the animals 

 over the stubs tra to (see Cole 1913&) and ascertain whether a 

 tendency to locomotion in this direction could be built up* 

 About forty treats were made with rigid non-looomotor animals* 

 The tube feet at first caught hold and clung to the substrate* 

 This became less and less manifest and the rigidity of the 

 myodermal sheath gave place to the flexibility that usually 



M* 



accompanies locomotion* Locomotion followed, however, less than 



s^> 



half the trials, the animal more often settling down obstinately 



Tt> W H/cf} 



in the place it was pushed t*. 



o 



Shen the locomotion did fallow it was, unfortunately, in 

 every case but one in the QPPO gi te direction to the puXl. It 

 continued for a few cm* only, <ahen the animal would settle down into 



the rigid state. The one animal that crawled in the direction 



it 

 fe* was pulled, continued to crawl all day* 



These results were complicated by the effects of contact 

 stimulation of the dorsal surfaces which induces close attachment 

 and cessation of locomotion. Hie reactions of the animals, then 

 for the most part may be considered a result of this stimulation 

 rather than a result of the pull. 



