DECEPTIVE APPEARANCES OF INTELLIGENCE 161 
modify the irritability of the tentacles for some time it 
might explain the change of behavior. This may not be 
the true explanation of the phenomenon, but it will serve 
to show how careful we must be, in studying the behavior 
of lower organisms, about inferring the presence of associa- 
tive memory. There have been almost no studies of the 
power of association in the Ccelenterates, where the various 
possibilities of error have been carefully excluded. 
Darwin in his work on earthworms attributes a certain 
degree of intelligence to these creatures on account of their 
peculiar habits of plugging up their burrows with dead leaves. 
The worms pull in the leaves of the linden by their tips, while 
the leaves of the rhododendron which are smaller at the base 
are pulled in by the petiole. Pine needles which frequently 
occur in pairs with a common base are not seized by the 
small end, which would cause difficulity in getting both 
needles into the hole, but’ by the enlargement at the basal end. 
Darwin gave the worms triangles of paper and found that 
they usually seized these by the most acute angle in carrying 
them to their burrows. The conclusions of Darwin that the 
behavior of the earthworms indicates a certain degree of 
intelligence was a very natural one. Hanel, however, 
who has repeated and verified Darwin’s experiments and 
performed a number of others, finds no ground for assuming 
any intelligence in the earthworm and ascribes the behavior 
of the animal to a series of more or less complex reflexes in 
relation to the form and chemical nature of the objects 
drawn in. There is no evidence of profiting by experience 
in the earthworm’s behavior and, however complex the acts 
performed, there is nothing that is thus far known that 
precludes us from considering them as belonging entirely 
to the reflex type. 
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