462 H. S. ^Jennings. 



tracted animal. Now on expanding, all parts extended more or 

 less proportionately to their extension in the contracted animal, 

 so that the original curved form was regained. In other words, 

 the structural conditions resulting in the curved form were not 

 really given up even in contraction, and were only made evident 

 when extension occurred. 



If the animal was compelled by repeated strong stimulation to 

 contract maximally in 11 parts, then in extension there was no 

 greater tendency to bend in the direction previously occupied than 

 in any other. And in about half the individuals this result 

 followed (after once the first habitual position found in nature 

 had been given up) even after a single stimulation, so that there 

 was no indication of anything like the formation of a new habit. 



What is the interpretation to be given to the numerous cases in 

 which bending in a certain direction when extended does induce, 

 in the way set forth above, bending in the same direction on a new 

 extension? Is this the formation of a habit? It is certainly a 

 condition of affairs that gives the same result as habit formation. 

 The anemone might indeed be looked upon as a sort of structural 

 model, illustrating the principles on which habit formation might 

 occur. A certain action (extension in a certain direction) leaves 

 structural peculiarities, persisting even in the intervals of action 

 (in the contracted state), which result in a repetition of the same 

 action. Is not this the picture that we commonly make for our- 

 selves of the real nature of habit formation? In the sea anemone 

 this seems to occur in a relatively gross way, but it appears difficult 

 to point out any difference in principle between this and habit 

 formation. If the persisting structural peculiarities were of such a 

 nature as to be hidden from observation, there would be no ground 

 for hesitation in calling these phenomena the formation of habits. 

 There can hardly be doubt that the striking individual peculiarities 

 of action and structure, described above, have arisen in precisely 

 this way, so that it plays, the part taken by habit formation in 

 higher animals. 



It would be well if the study of this matter could be extended 

 to the same individual for a long time, beginning with a young, 

 still regular, specimen, compelling it to live in a position where it 

 would have to extend in a definite irregular way. In this way the 

 development of the structural correlates of the habits (J) could 

 doubtless be observed. 



