With regard to dogs, Mr. Jennings ( "Animal Behaviour", reprinted from
the American Naturalist, Vol. XLII.) quotes a paper by Mr. G. van T.
Hamilton, which unfortunately I have not been able to obtain, describing
an experiment in which a dog had to learn that in order to escape from a
pen he must select for pressing a lever bearing the same sign as one that
he could observe on a sign-board elsewhere in the pen. The dog suc-
ceeded in this, but unfortunately "discovered a much simpler method of
action that accomplished the same results. He merely began at one end
of the series and pressed the levers in order till he came to the one that
worked." When electric shocks were attached to the wrong levers he
decided that he did not care to play that game any longer and the experi-
ments had to end. The dog's method was in fact the same as that
described by Mr. Hamilton as used by animals of various species in
learning to escape from a room, and by my monkey in opening drawers.
It is one in which the animal experimented on at least shows enough
intelligence to outwit the psychologist.

Lastly, Mr. L. W. Cole made some remarkable experiments with
raccoons that have been already referred to. Three signals of different
colours were shown to the raccoons in a certain order. Upon the appear-
ance of the third they had to mount some steps in order to obtain food.
The order could be varied and they had to learn to discriminate between
the series which meant and the series which did not mean food. The
raccoons achieved this rather complicated result ( Jennings, loc. cit., cf.
Gregg and McPheeters, "Behaviour of Raccoons to a Temporal Series of
Stimuli", J.A.B., 1913, p. 241. I regret that I have not been able to lay
hands on Mr. Cole's first paper) and would themselves claw up the
signals and, as will be mentioned elsewhere, tore down the wrong one.
Whether this remarkable result can be quoted as proof of the existence
of images of the unseen signals in the mind of the raccoons I will not
pretend to determine, but that it involved actions directed by relation to
that which was not present on the basis of past experiences in which the
object had been presented I am clear, and so to direct action is the
function which practical ideas perform. Mr. Cole, in his reply to Dr.
Hunter and Messrs. Gregg and McPheeters ( "Chicago Experiments with
Raccoons", J.A.B., 1915, pp. 158, etc.), points out that the explanations to
which his critics are driven come by a roundabout process to the admis-
sion of a function identical with that which he supposes. Thus he quotes
Dr. Hunter as writing: "Some intra-organic (non-orientation) factor not
visible to the experimenter must be assumed in order to explain a number
of the correct reactions of the raccoons and all of the successful reactions
of the children. These cues fulfil an ideational function." And again:
"By applying the term ideas to these cues, I mean that they are similar
to the memory idea of human experience so far as function and mechan-
ism are concerned" This really admits all that is here required. Of
what passes within another organism we can know nothing but the nature
of its functions and its origin. In full logical strictness this applies to
every human being as it does to animals.