1907] Jennings. — Behavior of the Starfish. 165 



a, 11; h. 11; c, 9; d, 11; c, 7. The combination c -\- d was 

 used five times \ a -{-h, eight times; d + e, six times; a -\- e, once. 

 Comparing these- results with those of the twenty-five experi- 

 ments before training began, the results of training are still 

 evident. At first, as we have seen, the pair c -\- d was not usea 

 at all, and the starfish could not be induced to employ it. Now 

 it is used in 16% of the cases. 



The innnediate effects of a brief period of training were 

 tested in a considerable number of individuals, by giving them 

 ten lessons on one or two days, then observing the effects when 

 they were allowed to right themselves freely. In almost all cases 

 the animals when tested immediately after one or two such 

 periods of lessons, continued to turn spontaneously on the rays 

 which they had been trained to use. The effects of so short a 

 period of training did not last for twenty-four hours, however. 



In the few cases in which little or no effect of training was 

 apparent, the starfish were large, stiff specimens, evidently older 

 than most of those employed. It seems clear that the behavior 

 of young specimens is more readily modifiable than that of old 

 ones. 



After the series of experiments with the starfish A and B 

 were about half finished, and it was clear that success in pro- 

 ducing more or less lasting modifications was assured, I began 

 work with three other specimens, F, G and H. The work with 

 these three was done in a more summary way than with the first 

 two, less time being devoted to details and to tests of progress, 

 and the course of training was much shorter. As a result, the 

 training was not so entirely successful in all of these cases. I 

 will give a brief sunnnary of results for each specimen. The 

 rays used by these three starfish in the ten preliminary free 

 reactions are given on page 144. 



Starfish F. — Ray b never used in the ten free reactions ; ray a 

 but three times. Training directed toward getting the starfish 

 to turn by the use of a -\- b for attaching and pulling. 



(^n the first day twelve lessons were given in rapid succession, 

 with but about a minute s interval, the starfish being driven to 

 turn on a and b by preventing other rays from getting hold. 

 The ray b invariably turned so as to face away from a, making 



