J. A. LOESER 233
significant reaction to stimuli (taste and smell) and the biological utility of
this procedure is clearly evident. Every living creature, from the protozoon
to man, directs its actions primarily and exclusively according to such sub-
jective stimuli; only in the second place does the problem arise as to how far
satisfaction of the stimulus is conducive to health. Even in the animal
kingdom this problem may become a momentous one, as when certain tribes
of ants cause the downfall of their community through excessive consump-
tion of the intoxicating secretion of the plant-louse. It must be remembered
that there is no question here of abnormal behaviour. On the contrary, it is
in such extreme cases that the fundamental law is most clearly evident, the
law of reaction to a sensation.
The frequently destructive behaviour in the animal's care of its young
is perhaps the most striking example of all. The fact that with many species
the devouring of eggs and off-spring is not an abnormality, but almost a
normal procedure, as with ants, bees, bumble-bees, also with some kinds of
fish, is clearly in favour of the exclusive principle of the subjective satisfaction
of impulse, a principle which rules even in opposition to elementary biological
purposes.
On the other hand, I have already given a detailed description of cases
in which ' genuine ' care of the brood, that is the care of the young animal
itself, as well as genuine friendship and love in animals, are found.
With regard to the problem of the so-called instinctive goal, migration
of birds of passage is of special interest. It used to be said that the true
migratory instinct determined both the passage and its destination. But
there is scarcely another instance which proves so unmistakably that all is
variable. At most it can be said that the impulse of flying is constant, the
impulse which is the fundamental phenomenon of the migration, and which I
have already described in detail elsewhere. This impulse signifies the be-
ginning or breaking forth of a completely undirected storm of motion—pro-
bably due to the action of hormones. In this storm the moving stimulus
is once more recognizable, the stimulus to which all migration is the natural
reaction. But the two factors essential to the instinct, that is, the way and
the goal are by no means pre-formed. On one hand, suitable adaptation to
circumstances is again possible, leading to the only action which is biolo-
gically (relatively) expedient. On the other hand, the loss is naturally very
great, due to the difficulties of the flight and to the inadequate intelligence
of the birds, which are not able to gauge the difficulties that face them. Fre-
quently they make fatal mistakes, as when the great flocks of singing birds
fly over the Black Sea by night and perish in thousands, because their wings
are frozen. The bird knows nothing, it neither recognizes its danger cons-
ciously, for it evidently does not even know that it is flying over a great
expanse of water, nor does instinct guard it unconsciously, but all the more
surely, from destruction.
RESULTS
So the nature of organic action proves to be quite different from what
has always been assumed. For the assumption of instincts makes the living
creature an automaton, which, if properly constructed, cannot make mistakes.
(The famous struggle for existence constitutes only an apparent exception.