STAR-FISH AND SEAUrtCHINS. 279 



available can be at once appreciated on witnessing 

 the performance, so that one is surprised, notwith- 

 standing the co-ordination displayed by all the 

 suckers, that they are able to accomplish the work 

 assigned to them. That the process is in truth a 

 very laborious one is manifest, not only from the 

 extreme slowness with which it takes place, but 

 also because, as already observed, in the case of not 

 perfectly strong specimens complete failure may 

 attend the efforts to reach the position of resting on 

 the equator — the Echinus, after rearing up a certain 

 height, becoming exhausted and again falling back 

 upon its ab-oral pole. I\roreover, in some cases it 

 is interesting to observe that when the equator 

 position has been reached with difficulty, the 

 Echinus, as it were, gives itself a breathing space 

 before beginning the movement of descent — drawing 

 in all its pedicels save those which hold it securely 

 in the position to which it has attained, and 

 remaining in a state of absolute quiescence for a 

 prolonged time. It then suddenly begins to protrude 

 all its feet again, and to continue its manoeuvre. 

 At any time during such a period of rest, a stimulus 

 of any kind will immediately determine a recom- 

 mencement of the manoeuvre. 



It will be perceived that as soon as the position 

 just described has been attained, gravity, which had 

 hitherto been acting in opposition to the righting 

 movement, now begins to favour that movement. 

 It might, therefore, be anticipated that the Echinus 

 would now simply let go all its attachments and 

 allow itself to roll over into its natural position 



