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The Concept of Instinct.
One of the chief examples of instinct, the piercing reaction of the lanneret
(Lanius collurio L.) has since been proved, in complete agreement with my
theory, to be the result of suitable actions according to the principle of trial
and error, knowledge of the thorn being only acquired after long investiga-
tion (Lorenz). Another pillar of the instinct theory has therefore fallen.
It is therefore evident that there is always a personal reason for the
action, and that nothing takes place without such a motive.
The second decisive point is the reaction to emotion, Every action is
always and only the response to an emotion. Where the psychological basis
is very narrow and slight and the physical possibilities very unmistakably
re-formed, the response may be of an exceedingly sterotyped nature. In
such cases the impression gained from superficial observation will be that the
actions are really mechanical.
It is well known that ichneumon flies sting strange caterpillars or grubs
which they find beneath the bark of a tree. The explanation of this mystery
was found by means of an experiment which once more proved the exclusive
effect of personal impulse. In this case, the impulse was provided by the
smell of the victims. It was proved that the ichneumon flies also stung small
paper cornets filled with the blood of the caterpillars or grubs, this blood
providing the characteristic smell. If there were an instinct or some complete
reaction unconsciously serving a vital purpose, it would necessarily include
the strange insect as the object of the action, for without this insect as its
object the action itself would be useless. It is therefore clear that here too
the stimulus merely leads to its own satisfaction irrespective of any object or
purpose, whereupon a true inner organic reflex action takes place, which
causes the laying apparatus to function.
The well-known experiment made in Germany a few years ago with
young storks in order to submit their instinct to an experimentum crucis ended
in a real catastrophe for this conception. The birds, which had been brought
from east Prussia to the Rhine and which had not hitherto migrated, should
have moved in a south-easterly direction, according to the instinct theory.
This is usual with storks the home of which is in eastern Germany, a fact
hitherto explained by the ' instinct of direction ', that is, a south-easterly in-
stinct. The result, however, was that the storks scattered in all directions.
Some were sighted in the Alps, some in France, but not a single one in the east.
The reason for this is that all the storks in eastern Germany, being, ' water
birds', must naturally move along the river valleys, etc., where they find
their food, and finally in the direction of the Black Sea, and the Bosphorus,
whereas when taken to western Germany they pursue the opposite course,
that is, like the west-German storks, they fly along the Rhine-Rhone valley
to the western Mediterranean and North Africa. In this case, however, the
most natural thing was for them to scatter, as storks, traditional flyers, mostly
migrate under the leadership of old ones, and this leadership was lacking.
THE PROBLEM OF PURPOSE
In all these occurrences in Nature as well as in all experiments, we have
repeated evidence of the uncertainty with which biological aims are achieved.
A glance at' fundamental instincts ' will prove this ; for example, the important
and decisive food instinct, where the fundamental divergence between the