Excerpt from
A Stroll Through the Worlds
A Picture of Invisible Worlds
Von Uexkull, J. (1934). A Stroll through the Worlds of Animals and Men. In C. Schiller (ed.), Instinctive Behavior, New York, International Universities Press, 1957.
This
little monograph does not claim to point the way to a new science. Perhaps it should be called a stroll
into unfamiliar worlds; worlds strange to us but known to other creatures,
manifold and caries as the animals themselves. The best time to set out on such an adventure is on a sunny
day. The place, a flower-strewn
meadow, humming with insects, fluttering with butterflies. Here we may glimpse the worlds of the
lowly dwellers of the meadow. To
do so, we must first blow, in fancy, a soap bubble around each creature to
represent its own world, filled with the perceptions, which it alone
knows. When we ourselves then step
into one of these bubbles, the familiar meadow is transformed. Many of its colorful features
disappear, other no longer belong together but appear in new relationships. A
new world comes into being.
Through the bubble we see the world of the burrowing worm, of the
butterfly, or of the field mouse; the world as it appears to the animals
themselves, not as it appears to us.
This we may call the phenomenal world or the self-world of the animal.
To some, these worlds
are invisible. Many a zoologist
and physiologist, clinging to the doctrine that all living being are mere
machines, denies their existence and this boards up the gates to other worlds
so that no single ray of light shines forth from all the radiance that is shed
over them. But les us who are not
committed to the machine theory consider the nature of machines. All out useful devices, out machines,
only implement our acts. There are
tools that help our senses, spectacles, telescopes, microphones, which we may
call perceptual tools. There are also tools used to effect our
purposes, the machines of out factories and of transportation, lathes and motor
cars. These we may call effector tools.
Now we might assume
that an animal is nothing but a collection of perceptual and effector tools,
connected y an integrating apparatus which, though still a mechanism, is yet to
carry on the life functions. This
is indeed the position of all mechanistic theorists, whether their analogies
are in terms of rigid mechanics or more plastic dynamics. They brand animals as mere objects. The proponents of such theories forget
that, from the first, they have overlooked the most important thing, the
subject which uses the tolls, perceives and functions with their aid.
The mechanists have
pieced together the sensory and motor organs of animals, like so many parts of
a machine, ignoring their real functions of perceiving and acting, and have
even gone on to mechanize man himself.
According to the behaviorists, man’s own sensations and will are mere
appearance, to be considered, if at all, only as disturbing static. But we who still hold that our sense
organs serve our perceptions, and our motor organs our actions, see in animals
as well as not only the mechanical structure, but also the operator, who is
built into their organs, as we are into our bodies. We no longer regard animals as mere machines, but as
subjects whose essential activity consists of perceiving and acting. We thus unlock the gates that lead to
other realms, for all that a subject perceives becomes his perceptual world and
all that he does, his effector world.
Perceptual and effector worlds together form a closed unit, the
Umwelt. These different worlds,
which are as manifold as the animals themselves, present to all nature lovers
new lands of such wealth and beauty that a walk through them is well worth while,
even though they unfold not to the physical but only to the spiritual eye. So, reader, join us as we ramble
through these worlds of wonder.
Anyone who lives in the
country and roams through woods and brush with his dog has surely made the
acquaintance of a tiny insect which, hanging from the branches of bushes, lurks
for its prey, be it man or animal, ready to hurl itself at its victim and gorge
itself with his blood until it swells to the size of a pea. The tick, though not dangerous, is
still an unpleasant guest of mammals, including men. Recent publications have clarified many details of its life
story so that we are able to trace an almost complete picture of it.
From the egg there
issues forth a small animal, not yet fully developed, for it lacks a pair of
legs and sex organs. In this state
it is already capable of attacking cold-blooded animals, such as lizards, whom
it way-lays as it sits on the tip of a blade of grass. After shedding its skin several times,
it acquires the missing organs, mates, and starts its hunt for warm-blooded animals.
After mating, the
female climbs to the tip of a twig on some bush. There she clings at such a height that she can drop upon
small mammals that may run under her, or be brushed off by larger animals.
The eyeless tick is
directed to this watchtower by a general photosensitivity of her skin. The approaching prey is revealed to the
blind and deaf highway woman by her sense of smell. The odor of butyric acid, that emanates from the skin glands
of all mammals, acts on the tick as a signal to leave her watchtower and hurl
herself downwards. If, in so
doing, she lands on something warm-a fine sense of temperature betrays this to
her-she has reached her prey, the warm-blooded creature. It only remains for her to find a
hairless spot. There she burrows
deep into the skin of her prey, and slowly pumps herself full of warm
blood.
Experiments with
artificial membranes and fluids other than blood have proved that the tick
lacks all sense of taste. Once the
membrane is perforated, she will drink any fluid of the right temperature.
If after the stimulus
of butyric acid has functioned, the tick falls upon something cold, she has
missed her prey and must again climb to her watchtower.
The tick’s abundant
blood repast is also her last meal.
Now there is nothing left for her to do but drop to earth, lay her eggs
and die.
The tick’s life history
provides support for the validity of the biological versus the heretofore
customary physiological approach.
To the physiologist, every living creature is an object that exists in
his human world. He investigates
the organs of living things and the way they work together, as a technician
would examine a strange machine.
The biologist, on the other hand, takes into account each individual as
a subject, living in a world of its own, of which it is the center. It cannot, therefore, be compared to a
machine, but only to the engineer who operates the machine. If we ask whether the tick is a machine
or operator, a mere object or a subject, the physiologist will reply that he
finds receptors, that is, sense organs, and effectors, that is, organs of
action, connected by an integrating device in the central nervous system. He finds no trace of an operator.
To this the biologist
will reply, “You mistake the character of the organism completely. No single part of the tick’s body has
the nature of a machine; everywhere operators are at work.” The physiologist will continue, undeterred,
“We can show that all the actions of the tick are reflex in character and the
reflex arc is the foundation of all animal machines. It begins with a receptor, which admits only certain
influences such as butyric acid and warmth, and screens out all others. It ends with a muscle which moves an
effector, a leg or proboscis. The
sensory cells that initiate the nervous excitation and the motor cells that
elicit motor impulse serve only as connecting links to transmit the entirely
physical waves of excitation (produced in the nerves by the receptor upon
external stimulation) to the muscles of the effectors. The entire reflex arc works by transfer
of motion, as does any machine. No
subjective factor, no engineer or engineers appear anywhere in this process.”
“On the contrary,” the
biologist will counter, “we meet the operator everywhere, not merely machine
parts. For all the cells of the
reflex arc are concerned, not with the transfer of motion, but with the
transfer of the stimulus. And the
stimulus must be ‘perceived’ by a subject; it does not occur in objects.’ Any machine part, such as the clapper
of a bell, produces its effects only if it is swung back and forth in a certain
manner. To all other agents, such
as cold, heat, acids, alkalies, electric currents, it responds as would any other
piece of metal. The action of
living organs is fundamentally different from this. Since the time of Johannes Muller we know that a muscles
responds to all external agents in one and the same way-by contraction. It transforms all external interference
into the same effective stimulus, and responds to it with the same impulse,
resulting in contraction. Johannes
Muller showed also that all external influences affecting the optic nerve,
whether ether waves, pressure, or electric currents, elicit a sensation of
light. Our visual sensory cells
produce the same perception whatever the source of stimulation. From this we may conclude that each
living cell is an engineer who perceives and acts, and has perceptual or
receptor signs (Merkzeichen) and impulses or effector signs (Wirkzeichen) which
are specific to it. The manifold
perceiving and acting of the whole animal may thus be reduced to the
cooperation of all the tiny cells, each of which commands only one receptor
sign and one effector sign.
In order to achieve an
orderly collaboration, the organism uses the brain cells (these, too, are
elementary mechanics) and groups half of them as “receptor cells” in the
stimulus-receiving part of the brain, or “perceptive organ,” the smaller or
larger clusters. These clusters
correspond to groups of external stimuli, which approach the animal in the form
of questions. The other half of
the brain cells is used by the organism as “effector cells” or impulse cells,
and is grouped into clusters with which it controls the movements of the
effectors. These impart the
subject’s answers to the outer world.
The clusters of receptor cells fill the “receptor organs” (Merkorgan) of
the brain, and the clusters of effector cells make up the contents of its
“effector organs” (Wirkorgan).
The individual cells of
the perceptor organ, whatever their activity, remain as spatially separate
units. The units of information
which they separately convey would also remain isolated, if it were not
possible for them to be fused into new units which are independent of the
spatial characters of the receptor organ.
The possibility does, in fact, exist. The receptor signs of a group of receptor cells are combined
outside the receptor organ, indeed outside the animal, into units that become
the properties of external objects.
This projection of sensory impressions is a self-evident fact. All our human sensations, which
represent our specific receptor signs, unite into perceptual cues (Merkmal)
which constitute the attributes of external objects and serve as the real basis
of our actions. The sensation
“blue” becomes the “blueness” of the sky; the sensation “green,” the
“greenness” of the lawn. These are
the cues by which we recognize the objects: blue, the sky; green, the lawn.