148 Universitij of California Publications in Zoology. [Vol. 4 



During the moments before the unified impulse appears, 

 often several rays have attached themselves and are pulling 

 against one another. Now the unattached tube feet show great 

 diversity of action. Those of a given ray stretch out in the 

 direction in which the attached ones of that ray are pulling, so 

 that there is a sort of partial unity of impulse for the single ray. 

 In an unattached ray the tube feet point usually in the direction 

 pulled by the nearest attached ray. If two rays near by are pull- 

 ing in different directions, often the tube feet of the unattached 

 rays, or of the disk, stretch out first toward one side, then toward 

 the other. 



This state of indecision usually lasts but a short time; but 

 sometimes it is prolonged. Thus, in a certain case, one ray (c) 

 did not attach itself, while the other two pairs became attached 

 in a symmetrical way on its right and left. These four rays 

 became attached nearly simultaneously, and about the same num- 

 ber of tube feet were holding on each. There was thus little to 

 determine an impulse to one side rather than the other, so that 

 the starfish remained for several minutes on its back, the rays 

 vainly pulling against one another. Sometimes all the five rays 

 become attached and pull against each other for several min- 

 utes in the same way. As might be expected from the great 

 variety of factors which may determine the impulse, the state 

 of indecision never lasts indefinitely; finally the unified impulse 

 appears ; certain rays release their hold and allow themselves to 

 be pulled over by the attached rays. 



Further account of the unified impulse is reserved till we 

 have investigated habit formation, since the latter throws much 

 light on the determination of the impulse. 



Formation of Habits in the Starfish. 



We have seen above that when the starfish begins to act in 

 a certain way, it persists in that action for some time, even in 

 spite of opposing conditions. Furthermore, we have seen that 

 individual starfish have a more or less permanent "set" toward 

 acting in certain ways, — toward using certain rays in one man- 

 ner, others in another, in the righting reaction and the like. 

 These facts naturally suggest the possibility that the starfish 



