ntly imitative behavior in _P. irus_.

The work of Shepherd (1910) agrees closely, so far as evidences of
ideation are concerned, with that of Thorndike. He obviously strives for
conservatism in his statements concerning the adaptive intelligence of
his monkeys, all of which belonged to the species _P. rhesus_. At one
point he definitely states that they exhibit ideas of a low order, or
something which corresponds to them. Satisfactory evidences of reasoning
he failed to obtain.

Franz's (1907, 1911) studies of monkeys, unlike those mentioned above,
have for their chief motive not the accurate description of various
features of behavior but instead knowledge of the functions of various
portions of the brain. His results, therefore, although extremely
interesting and of obvious value to the comparative psychologist, throw
no special light upon the problem of ideation.

The investigation by Hamilton (1911) of reactive tendencies in _P.
rhesus_ and _irus_ yielded preeminently important data concerning
complex behavior. For the ingenious quadruple-choice method devised by
this observer showed that mature monkeys exhibit fairly adequate types
of response. As Hamilton's interest centered in behavior, he did not
discuss ideation, but this does not prevent the comparison of his data
with those of the present report, and the agreement of his findings with
my own is obvious.

My work contrasts sharply with that briefly mentioned above in that I
applied systematically and over a period of several months an
experimental method suited to reveal problem solving ability.
Previously, the so-called problem or puzzle-box method had been used as
a means of testing for the presence of ideas. For this I substituted the
multiple-choice method. One of the chief advantages of this new method
is the possibility of obtaining curves of learning for the solution or
attempted solution of relational problems of varying difficultness. I am
confident that these curves of learning will prove far more valuable
than such data as are yielded by the puzzle-box method.

The Pithecus monkeys, which I studied intensively, yielded relatively
abundant evidences of ideation, but with Thorndike I must agree that of
"free ideas" there is scanty evidence; or rather, I should prefer to
say, that although ideas seem to be in play frequently, they are rather
concrete and definitely attached than "free." Neither in my sustained
multiple-choice experiments nor from