58 SECRETS OF ANIMAL LIFE 



were given ninety-six hours after the end of the 

 training. Other members of the class behaved in 

 a similar way, but beyond the limit of ninety-six 

 hours no answer could be wrung out of any of them. 

 There was a sudden and final declinature to answer, 

 which further experimentation showed to have no 

 necessary connection with fatigue. 



In some of the many sets of experiments, the 

 punctilious carefulness of which deserves high 

 praise, there was an interesting waning in the 

 number of mouth-movements in any one answer. 

 Following a maximum number of mouth-move- 

 ments in a response towards the middle of the series 

 of trials, the number gradually diminished to the 

 end of the series. This indicated that the snails 

 were becoming adapted to a stimulus which was 

 not being followed by any reward. But the general 

 result stands out clearly, and considering the humble 

 creatures involved, is of very considerable interest. 

 Snails which gave no mouth response to pressure 

 on the foot were so affected by the simultaneous 

 application of pressure to the foot and food to the 

 mouth that they then gave the mouth answer to 

 pressure on the foot. The effect of training with 

 the simultaneous stimuli persisted for ninety-six 

 hours after the training stopped. The snail learned 

 its lesson, but the registration of experience, memory 

 in psychological language, was shortlived. 



Those who have some acquaintance with fresh- 

 water snails may be inclined to think that Miss 

 Thompson's pupils were extraordinarily well be- 



