158 Univei'siiij of California Puhlications in Zoology. [Vol. 4 



The starfish was placed on its back. The rays and tube feet 

 began to twist and endeavor to tal^e hold, but this was prevented 

 in the rays a, d and e, by stinuTlating their tube feet with a glass 

 rod whenever they tried to attach themselves, — so that only the 

 rays h and c were able to take hold. Ten experiments were per- 

 formed in series, with intervals of two minutes between them. 

 As the first few experiments are very instructive, they will be 

 described in detail. 



1. The first experiments showed strongly the tendency of 6 

 to rise up and go over in place of twisting, attaching itself, and 

 pulling. In experiment 1, though h and c were the only rays 

 permitted to attach themselves, h obstinately refused to do so, 

 and persisted in rising and attempting to .swing over in the usual 

 way. After some delay, c attached itself and turned the starfish 

 unaided, — h consistently refusing to play any part but its usual 

 one. 



2. In the second experiment I restrained all the rays except 

 h from attaching themselves. After much threshing about, h 

 finally came in contact with the bottom and took hold. Then c 

 was allowed to assist, and the two turned the starfish. 



3. This time h and c were left equally free to act, whereupon 

 c turned the animal unaided, — h again refusing to attach itself. 



In the next experiments my efforts were concentrated on h, 

 in an attempt to overcome its refusal to attach and pull. 



4. In the fourth experiment I again prevented the attach- 

 ment of all rays but h. But the latter persisted in rising, waving 

 about, and endeavoring to swing over in its usual way. All the 

 other rays made repeated attempts to attach themselves, which I 

 prevented. But the animal kept twisting and squirming about 

 until finally it managed to swing h over in the usual way, — so 

 that by perseverance it had managed to right itself without 

 attaching any of its rays. 



5. Again h was obstinate, but all the other rays were pre- 

 vented from attaching, and finally in the course of its squirming 

 h accidentally came against the bottom. This, as in experiment 

 2, seemed to operate as a stimulus to cause the disposition of h 

 to change; it now attached itself. In order to give h practice 

 in doing the active work of turning, I still prevented all the 



