his right hand eight
times, his left twice. In the second series, given the following day, he
used the right hand three times and the left seven times. From this we
should have to infer that he is ambidextrous.

A female _rhesus_ monkey which had been brought to the laboratory only a
few days previously showed a preference for the right hand by the use of
it fourteen times to six.

In connection with these data which are, I should repeat, too scanty to
be of any considerable value, I wish to describe my own experience.
Although naturally left-handed, I am by training right-handed to the
extent of having been able to use my hands in writing and in various
other activities equally well at the age of twelve. I am at present
ambidextrous in that there are many things which I do with equal
readiness and skill with either hand. Delicate, exact, and finely
coordinated movements, such as those of writing and using surgical
instruments, I perform always with my left hand while grosser movements
involving the whole hand or arm, I am rather likely to perform with my
right hand.

It seems not improbable in the light of my own experience that we shall
find some specialization among the lower animals with respect to
preference for right and left hand or arm. I should not be at all
surprised to discover that it is the rule for animals to possess or to
develop readily definite preference for one hand in connection with a
given act of skill and to have quite as definite a preference for the
other hand in connection with a radically different kind of act.

2. _Instinct and emotion_

Of the many presumably instinctive modes of behavior which were
observed, only those which have to do with social relations seem
especially worth reporting. From among them I shall select for
description a few which have already been referred to in connection with
the experimental observations.

_Maternal Instinct_

Aspects of the maternal instinct I had opportunity to observe in Gertie,
who on February 27 gave birth to a male infant, I present below the
substance of a previously published note on her behavior (Yerkes, 1915).

"On February 27 one of the monkeys of our collection gave birth, in the
cages at Montecito, to a male infant. The mother is a _Macacus
cynomolgus rhesus_ (_P. irus rhesus_) who has been described by Hamilton
(1914, p. 298) as 'Monkey 9, Gertie, _M. cynomolgus rhesus_ (_P. irus
rhesus_). Age, 3 years 2 months. (She is now,