1907] Jennings. — BcJtavior of ilte Starfish. 155 



may be called the remarkable versatility of the starfish. This 

 animal may do in an indefinite number of different ways any- 

 thing that it may do at all. Its locomotion is an excellent type 

 of its entire behavior in this respect. The starfish is not ham- 

 pered by any considerations of anterior and posterior; it may 

 move with any one of its rays in the lead, or with any interradius 

 in advance, or indeed in any intermediate direction, so that its 

 possibilities as to variations of direction of locomotion are really 

 unlimited. In the same way, as we have seen in detail, it may 

 right itself in an indefinite number of different ways. It shows 

 the same versatility when confronted with such a problem as the 

 removal of the rubber tube placed on its arm, or the escape from 

 confinement by tacks. It may and does solve these problems 

 in any one of many different ways; almost any method which it 

 adopts proving effective in the long run. Under these conditions 

 it is evident that there is little occasion for adopting any par- 

 ticular method as a habit, even if habit-formation is possible. ^- 



Conditions Required for Habit-Formation. — These facts lead 

 to a careful consideration of just what conditions are required 

 for habit-formation. These appear to be the following : (1) The 

 organism must be presented with a situation or "problem" that 

 shall cause it to react and to continue reacting till the situation 

 is essentially changed, — the problem "solved". (2) The organ- 

 ism must react in several different ways; it must "try" to 

 "solve the problem" in more than one manner. (3) It must 

 be able to solve the problem or relieve the situation in only one, 

 or at least in only a limited number, of these ways. If this 

 third condition is not fulfilled, there is no strong ground for 

 any special method being selected, and so for the formation of a 

 habit. If any method will work, none is specially preferable. 



It is not easy to devise "problems" fulfilling all these require- 

 ments, for organisms with which we have so little in common as 

 with the starfish or with other animals in a corresponding low 

 position in the scale of development. The problems thus far 



'"These considerations on the "versatility" of the starfish forced upon 

 one by the results of an experimental investigation, are interesting in view 

 of the old idea that the reactions of such lower animals are fixed and un- 

 varying. The behavior of lower organisms differs from that of higher ones, 

 rather in its great indefiniteness and inconstancy. 



