VERMES, FLY LARVAE, AND ECHINODERMS 213 



After I had completed this part of the work, Cowles 

 reported to me personally that he found that positive star- 

 fish, when placed on the dorsal surface, always extend the 

 tube feet toward the shaded side of the body and turn from 

 the source of light, whereas in the normal position they 

 extend the tube feet toward the light. This seems to show 

 clearly that the direction of locomotion is not regulated by 

 the direct effect of light on these structures, as suggested 

 above. 



