160 MODIFICATIONS OF BEHAVIOR 
carried by the tentacles to the mouth and there swallowed, 
to be ejected as inedible after a longer or shorter period. 
After a few days, the number varying in different individuals 
from two to five days, the fragment is no longer swallowed 
and, in about an other two days, the tentacles will no longer 
take hold of it. This procedure is more regular in the case 
of pellets of paper than in the case of India rubber, in which 
results were very variable. The results seem to indicate a 
certain amount of persistence of impressions, when the latter 
are received several times in succession at short intervals. 
“The first impression which persists is one in the mouth 
region leading to refusal of the pellet. As this is strengthened 
the sequence is further abbreviated, an inhibitory stimulus 
would seem to proceed from the mouth to the tentacles 
preventing them from gripping, when the stimulation due to 
contact with the filter-paper has passed from them to the 
mouth. 
“A further point of interest is that what does persist seems 
to remain a property of the tentacles affected, and of that 
part of the mouth directly related to them. It does not 
appear to be a possession of the entire animal, for other 
tentacles, on the opposite side for instance, can be tricked 
subsequently, at any rate once or twice, before they too 
exhibit the inhibitory reaction.” The effects of the ex- 
perience were found to be lost after from six to ten days. 
Whether or not we have in this instance the formation of 
a new association, as the behavior of the anemone seems 
to indicate, is not entirely certain. It is possible that the 
seat of the change of behavior is in the tentacles alone. 
Allabach has shown that after the tentacles of Metridium 
have responded to a stimulus a few times their production 
of mucus becomes much diminished and this probably 
affects tHeir subsequent activity. If this factor would 
