1907] Jennings. — Behavior of the Starfish. 57 



essentially cliffei'ent laws. Second, the movements of organisms 

 form a system which is of such a nature as to assist the internal 

 processes and keep them in progress even under unfavorable and 

 changing, conditions. Behavior is the method of regulating the 

 internal processes by means of external movements. To keep 

 the internal processes going, the animal must do certain outward 

 things. Thus behavior and the internal processes are not two 

 things ; they are a unit and can not be understood separately. 

 The regulatory character of behavior has been so clearly demon- 

 strated by recent studies in both higher and lower animals^ that 

 no apology is required for frankly making it the basis for an 

 account of the behavior of a given animal ; this we shall do in the 

 case of the starfish. 



The unity of the internal processes and behavior is very 

 evident if we include in behavior such movements as the ex- 

 piration and inspiration of air, the movements of the stomach 

 and intestines in digestion, the beating of the heart, and the like. 

 But it is scarcely less evident in the movements which animals 

 make in search of pure air, of food and of other things necessary 

 to keep the internal processes going. These movements make up 

 a large share of behavior in man as well as in other organisms. 



Furthermore, in order that the internal processes constituting 

 life shall be kept in progress, the organism must be retained in 

 certain favorable conditions, and kept out of others that impede 

 the processes. It nuist not be allowed to become too hot or too 

 cool; it must not be poisoned nor crushed; it must not be de- 

 voured by enemies. Strangely enough, we find the movements 

 of all organisms to be of such a character as tends to keep the 

 creature under favorable conditions, to protect and defend it. 

 Sometimes they fail, and the failures are as interesting as the 

 successes. 



The general problem of physiology is: How are the bodily 

 processes kept going? The special problem of behavior is : How 

 are the bodily processes kept going by the aid of movements? 

 And how does it happen that the movements are of such a char- 

 acter as to keep the processes going? 



'See Jennings, Behavior of Lower Organisms (New York, 1906). 



