150 University of California Publications in Zoology. [Vol. 4 



tend to spontaneously right itself in that manner for, say, half 

 an hour, this would be an example of what is meant by a tem- 

 porary habit. 



Preyer (1886) has given in his valuable paper on the move- 

 ments of the starfish certain observations which might bear upon 

 habit-formation. He tried placing specimens of the starfish on 

 a smooth hemispherical surface, from which it would be as easy 

 to crawl in one direction as another, in order to determine 

 whether the animals prefer moving with any particular ray in 

 advance. The general result of many varied experiments, with 

 many specimens, was that no particular ray was preferred above 

 others. But in repeated experiments with single individuals, he 

 found in several cases that the given individual showed a marked 

 preference for movement with a certain ray in advance. Thus, 

 a specimen of Astropecten pentacanthus moved with the ray 4 

 (ray d, fig. 10) in advance fifteen times out of a series of twenty 

 experiments. Such results suggest the possibility that the pref- 

 erence is due to habit, — though this possibility was not men- 

 tioned by Preyer. I endeavored to determine experimentally 

 whether such a habit could be formed. Starfish were placed in 

 such a situation as that described by Preyer, then the tips of 

 one or two rays were strongly stimulated, in order to compel the 

 starfish to move toward the opposite side. By thus compelling 

 the animal to move many times with a certain ray in advance, 

 it was thought possible that a habit might be established, so that 

 the starfish would move with that ray in advance even when not 

 compelled to do so. But unfortunately I found it impossible to 

 drive the starfish in a certain direction. When the tips of certain 

 rays were strongly stimulated, the animal, instead of fleeing, in 

 nine cases out of ten merely contracted its tube feet strongly, 

 so as to shrink close against the surface and cling tightly there. 

 This test for habit-formation was therefore abandoned. 



In certain other experiments Preyer gives a statement of 

 results which if confirmed would amount directly to temporary 

 habit-formation, or to "learning by experience." He tried to 

 confine the starfish by means of large flat-headed pins, placed 

 in the angles between the rays, close to the disk, and driven 

 into the board on which the starfish lay. The animals tried by 



