12- 



discussed in connection ith the step reflex, a 

 extension sometimes occurred due probably to an increased 

 tension of the ampullar muscles. Next/ in sequence in the 

 non-loco -otor tube feat was the retraction of the tube foot 

 and a consequent mo Ting of the piece of celluloid toward 

 the ray* Thin does not involve release of the substrate by 

 the disc as does the withdrawing on stimulation of the side 

 of the column yind is probably the response of the tube feet 

 t *t is involved when the ani.rul shrinks^ down on the substrate 

 after having ben disturbed* 



and wi thdra'al oj; isolated tubft 



An isolated tube foot preparation does not show typical 

 withdrawal reactions, because of course, the reciprocal action 

 of the ampulla is absent* Harsh stimulation of the column of 

 the attached tube foot preparation was fount to cause release* 

 Shortening by a slow contraction of the longitudinal 

 nusculnture was found to follow sever* stimulation f any part 

 of the tube foot, even against a strong water pressure , 



Response jfco internal changes 



Release and withdrawal nc of attached tube feet may occur 

 as a response to a change of internal physiological conditions* 

 Thus tin animal all of whose feet were tightly attached, one 

 minute, may the next minute be seen in active locomotion about 

 the aquarium* The factors governing this response will be 

 taken up elsewhere* 



with withdrawing reaponsa* 



The step reflex * is I think, merely a notification of 



The first description that "l can find o'^ 1 the*steprefiex*" 

 is that Given by Reamur &71CJ, After describing the morpho- 

 logical connection of the ampullae ("tiny pearl like* balls') and 

 the "legs" (tube feat? he goes on to say "But one brings out 

 the whole ingenious mechanism of it when one presses the finger 

 on one of the MMlls**^ It is seen to empty and at the same 



