PRIMITIVE TYPES OF INTELLIGENCE 181 
The criterion of intelligence which we have adopted—the 
power of forming associations—is one which is accepted by 
a considerable number of comparative psychologists. Un- 
fortunately the term intelligence is used in a variety of senses 
by different writers—a fact which is in part responsible for 
the different expressions of opinion as to where in the animal 
kingdom intelligence makes its beginning. The acute 
Father Wasmann will have none of intelligence in any 
animal below man, but as he defines it, the term connotes 
the power of reasoning by the use of general concepts. 
The controversy which has arisen over this employment of 
the term is a matter for the lexicographer instead of the 
psychologist, and so long as a writer makes his peace with 
the dictionary we have no quarrel with him. We prefer, 
however, to employ the term in its more widely accepted 
meaning. 
As stated in a previous chapter, there is no evidence that 
there is any power of forming associations in the Protozoa. 
In the Ceelenterata behavior, although of the reflex type, 
is often highly plastic and capable of being modified in 
many ways as the result of previous experience; but while 
intelligence has often been claimed for these forms, there is, 
in the opinion of the writer, no case in which the formation 
of associations is satisfactorily proven. The same state- 
ment may also be risked for that large and miscellaneous 
assortment of animals grouped under the term Vermes. 
The behavior of Echinoderms is certainly complex and plastic 
to a remarkable degree, but even in this group the power 
of forming associations is very doubtful. Preyer, who has 
made a very thorough study of the behavior of the starfish, 
claims to have discovered indubitable indications of intelli- 
gent action, but the later studies of Jennings and Glaser on the 
behavior of starfish and ophiurans failed to confirm Preyer’s 
