66- 



O) 



the passive movement of the middle x ray which will be 



A 



discussed in connection with the fourths type* ifte impulse 

 spreads to the tube feet of the two unattached rays* The 

 coordination of these is followed by their raising up over the 

 diso and moving toward the initiating rays in the Mae way and 

 according to the same principles* as described above* 

 (types 1 and 2), 



The fourth type is as follows* 



4. "Four of the rays take hold, two extending to the right, 

 two to the left. Then the fifth ray, (which we nay eall the 

 posterior one) is lifted straight up and swings directly over 

 till its ventral surface reaches the bottom, while the anterior 

 attached pair walks backward beneath the posterior attached 



pair the latter walking forward over the surface of the (former)" 



f-M if 

 mis type of righting is sketched en p. In oase 



of Plaaster it is more apt to scour if the animal is very much 

 relaxed* The sequence of the events as I have observed it is as 

 follows. The anterior rays twist toward each other and the 

 coordinated impulse spreads over (or is already in) the starfish 



a * in type ! This results in the twisting toward them of the 



p*t 

 lateral rays and the bending up of the posterior ray* fate to 



the relaxed state of the starfish ersoroe other physiological 

 factor which prevents the lateral arms assuming their usual state 

 of ventro flexion, these droop to the atubstrate and become the 



e,e 

 "posterior attached arms" (rays fc in fig] 1 *) How the fadtor 



which causes the moving forward of the back rays xhen the direc* 

 tion of the coordinated impulse* as seen by the activity of the 

 Initiating rays causes locomotion in the opposite direction is 

 the same factor, X think, which amuses the complex coordination 

 of the deviation reaction, I have presented the evidence which 

 leads me to think that the factor in question has to do with 



