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- 
