1^07] Jennings. — Behavior of the Starfish. 55 



PAGE 



Irregular reactions 129 



Diverse methods of beginning the reaction 132 



The righting impulse 132 



Determination of actions before the impulse 135 



Factors in determining the direction of the impulse 135 



Light 135 



Structural differences in the rays 136 



Rays that first come in contact with the substratum 136 



Side of the ray that first comes in contact 137 



Tilting of the body 137 



Contact with an object 137 



Rays that first become attached 138 



Number of opposed attached rays 138 



Relative number of tube feet attached in different rays 139 



Coordinated position and action of the rays 139 



Experimentally releasing certain rays 140 



Intense stimulation of certain rays 141 



Impulse retained from previous reaction 141 



Impulse present before the animal is turned 141 



Permanent tendency to turn toward a certain pair of rays 142 



Summary on the righting impulse and the factors determining it 145 



Persistence of the impulse 145 



Changing an established impulse 146 



Indecision 147 



Formation of Habits in the starfish 148 



Habits in other lower animals 149 



Nervous system of the starfish 149 



Definitions of habit 149 



Preyer's work on "intelligence" in the starfish 150 



Preyer's work on the brittle star 151 



"Why Preyer called the behavior "intelligent" 152 



Glaser's negative results 153 



Negative results of the present author 154 



' ' Versatility ' ' of the starfish as possible cause of lack of habit for- 

 mation 155 



Conditions required for habit formation 155 



Method for training the starfish 156 



Experiments in training the starfish 156 



Positive results 168 



Nature of the habits formed 168 



Why habits are not readily formed 168 



Why they soon disintegrate 169 



The unified impulse and the determination of the varied activities under 



its influence 16" 



The problem 1'''^ 



Effect of external conditions 171 



Action of parts in the interest of the whole 171 



