What we are reading… Wanderings through the Environments of Animals and Humans | Von Uexküll

by | 26 Dec 2010

(Streifzüge durch die Umwelten der Tieren und Menschen (1933), translated by Stephen Connelly [*])

Translator’s note: In this short introduction von Uexküll outlines his view of passive consciousness and its relation to affective being which would prove so inspirational to among others Heidegger, Deleuze and Agamben.  The selected text speaks suggestively of ‘little machinists’ and, in its terminology of perceptual and motor signs, of the possibility of a ‘biosemiotics’.  Von Uexküll mentions Kant in the final paragraph.  One may view this text as playing for von Uexküll the same role as the ‘Transcendental aesthetic’ plays for Kant in the Critique of Pure Reason.


Figure 1 - The tick (a deer tick)Every country dweller who wanders often with his dog through woods and bushes and certainly come to know a miniscule animal which, hooked to the branches of bushes, watches out for its prey (whether it be man or animal) in order to throw itself upon its victim and gorge on its blood.  The animal, about a millimetre or two in size, then swells until it attains the size of a pea (see Fig.1).

The tick or ixodoidea is certainly not dangerous, but for all that is no less an unpleasant guest for mammals and humans.  The course of the tick’s life has been so well clarified by recent work that we may sketch a rapid and exhaustive portrait of it.

The beast which emerges from the confines of the egg is not completely formed, for it still lacks a pair of legs and genitalia.  At this stage it is already possible of attacking cold blooded animals, such as lizards which is espies from atop a blade of grass.  After numerous moltings, it acquires the missing organs and devotes itself to the tracking down of warm-blooded animals.

After having been fertilised, the female clambers with her full complement of eight legs to the end of an overhanging branch of any kind of tree which has sufficient height to allow it either to fall on small mammals as they run beneath it, or to be carried off by large animals which pass.

Lacking eyes, the beast finds its way to its watchtower with the aid of a generally light-sensitive skin.  The approach of its prey manifests itself to the olfactory organ of this blind and deaf highway bandit.  The weak odour of butyric acid, which is emitted by the sebaceous follicles of all mammals, acts upon the tick like a signal causing it to quit its sentry post and fall.  Should it fall upon something warm, which its acute sense of temperature detects, then it has attained its prey – the warm-blooded animal – and it needs nothing more than to find with its tactile sense the weakest locus upon the pelt so that it may bury its head in the epidermis of its prey.  From there it slowly pumps a flow of warm blood.

Tests with artificial membranes and liquids other than blood have shown that the tick is not provided with a sense of taste, for, once having perforated the membrane, any and every liquid is absorbed so long as it has the correct temperature.

If the tick, activated by the sign of butyric acid, falls on something cold, then it has missed its prey and must once again scale its watchtower.

The tick’s abundant feast of blood is also its last meal, for there remains nothing for it to do save let itself fall upon the ground, deposit its eggs, and die.

The salient events of the life of the tick offer us an appropriate touchstone with which to substantiate the validity of the biological approach against the physiological, insofar as this has been pursued up to now. For the physiologist, each living being is an object situated in his human world.  He examines the organs of living beings and their synergy, just like a technician explores an unknown machine.  On the contrary, the biologist takes into account that each living being is a subject which lives in a world which is proper to itself and of which it forms the centre.  Also, he must not compare it to a machine, but uniquely to a machinist that pilots the machine.

We pose the question simply: is the tick machine or machinist, a simple object or a subject?

Figure 2. Reflexive Arc of Animal MachineThe physiologist will interpret the tick like a machine and will say “One can distinguish in the tick receptors i.e. sense organs [Merkorganen], and effectors i.e. motor organs [Wirkorganen], and these are linked one and the other by an apparatus of control within the central nervous system.  The whole is a machine of which no machinist is visible.  “It is precisely there that the error lies,” the biologist will reply.  Not a single part of the tick’s body possesses the character of a machine; there are machinists acting everywhere. The physiologist will continue, unperturbed: “Precisely, we will easily show that with the tick all its actions rest exclusively on reflexes1A reflex initially designated the uptake and the return of a light beam by a mirror. Applied to living beings one understands by reflex the uptake of an exterior stimulus by a receptor and the response by the effectors of the living being, activated by the stimulus. Thus is this transformed into a nervous excitation which must pass numerous stages between receptor and effector.  The route thus travelled shall be called the reflexive arc., and the reflexive arc forms the foundation of such an animal-machine” (See Fig.2).  This arc commences by a receptor, i.e. an apparatus which permits entry only to certain determined influences, like butyric acid or heat, and hides all the others.  It terminates in a muscle which puts into movement an effector, be it a walking or a foraging apparatus”.

“The sense cells, which provoke sense excitation, and motive cells, which provoke the impulse of movement, serve only as transmission elements, for the conduction of waves of bodily excitation (which are produced in the nerves) right unto the effectors’ muscles.  The ensemble of the reflexive arc functions with the transmission of movement like a machine.  No subjective factor, whether as one or several machinists, appears anywhere in the phenomenon”.

“What happens is precisely the opposite,” the biologist will reply.  “Everywhere here it is a matter of machinists and not pieces of a machine.  For all the particular cells of the reflexive arc function not with the transmission of movement, but with the transmission of the stimulus.  Yet the stimulus must be perceived by its subject and is not offered up to objects”.

Every part of a machine, like the hammer of a bell, only functions like a machine to the extent that it is balanced in a determinate manner on one side and the other.  In respect of all other interventions, such as cold, heat, acidity, alkalinity or electric current, it responds with whatever chunk of metal.  But we presently know, since Johannes Müller, that a muscle behaves entirely differently.  It responds to all exterior interventions in the same manner: by a contraction.  Every exterior intervention is transformed by it into the sole same stimulus of which the response is the sole same impulse which leads the cellular body to a contraction.  Johannes Müller has shown further that all the exterior actions which our optic nerves encounter, whether it be a question of waves, of a pressure or an electric current, provoke a luminous sensation, i.e. that our visual cells respond by the same “perceptual cue” [Merkzeichen].  We can conclude from this that each living cell is a machinist who perceives and acts, and as such it possesses a perceptual index and an impulsion of “motor cue” [Wirkzeichen] which are appropriate to it (specific).  The diversity of the animal subject’s perception and action in its composition must thus be related to the collaboration of little cellular machinists, each only disposing a perceptual cue and a motor cue.

In order to permit an ordered collaboration, the organism avails itself of cerebral cells (these too being elementary machinists), and it groups more or less half of them into associations of perceptual cells in the part of the brain which receives stimuli, “the perceptual organ” [Merkorgan].  These associations respond to groups of stimuli which address themselves like questions to the animal subject.  The organism employs the other half of the cerebral cells as “motor cells” or impulsive cells and groups them in associations with which they dominate the movements of the effectors which deliver the responses of the animal subject to the exterior world.

The associations of perceptual cells fill the perceptual organs of the brain, and the units of motor cells form the contents of the motor cells of the brain.

If in this manner we can represent a perceptual organ as a place of diverse associations of cellular machinists, bearers of specific perceptual cues, these machinists remain however as spatially separated individuals.  Their perceptual cues rest equally isolated if they do not have the possibility of dissolving into new units , outside the spatially defined perceptual organ.  And this is effectively possible.  The perceptual cues of one group are reunited from without by the perceptual organ, from without by the animal body, in units which become the properties of objects situated without the animal subject.  These facts are well know to all.  All our human sensations, which represent our specific perceptual cues, are unified in properties of external things and which serve for us as perceptual signs [Merkmal] for our activity.  The sensation “blue” becomes the “blue” of the sky; the sensation “green” becomes the “green” of the lawn, etc.  We recognise the sky upon the perceptual sign “blue” and we recognise the lawn upon the perceptual sign “green”.

Exactly the same thing occurs in the motor organ.  The motor cells play here the role of elementary machinists, which are in this case ordered in groups articulated according to their cues or motor impulses.  Here too, it is possible to reunite the isolated motor cues into units which act on muscles which are their subordinates, like impulses of movement closed upon themselves or like melodies of rhythmically articulated impulsions.  Following that, the effectors put to work by the muscles impress their “motor sign” [Wirkmal] into objects situated exterior to the subject.

The motor sign which the subject’s effectors confer upon the object is immediately recognisable – as the wound that the tick’s perforating proboscis inflicts on the skin of the mammal it attacks.  However, it is the laborious discoveries of the motor signs of butyric acid and heat which completes the portrait of the tick acting in its environment.  To peak metaphorically, each animal subject learns its object by a two pronged pincer: one prong perceptual and one motor.  It confers on the object with one prong a perceptual sign and with the other a motor sign.  Certain determinate properties of the object become sorts of bearers of perceptual signs and others bearers of motor signs.  All the properties of an object being relayed one and another across the structure of this object, the properties that encounter the motor sign across the object must influence the bearer properties of the perceptual sign and even work upon it a modification.  One could express this more briefly by: the motor sign extinguishes the perceptual sign.

What is decisive for the carrying through of each act of some subject animal, beyond the choice of stimuli that the receptors permit to pass, and beyond the disposition of muscles which offer the determined possibilities of activation, is above all the number and the disposition of the perceptual cells which, with the help of their perceptual cues, indicate objects of the environment by perceptual signs, and the number and the disposition of motor cells which, with their motor cues, fill the same objects with motor signs.  The object is solely to this extent a part linked to action, in that it must possess the necessary properties enabling it to function on one side as a bearer of perceptual signs and on the other as a bearer of motor signs., which must each be in relation across the integrated microstructure [Gegengefüge].

Figure 3 — Functional circleThe relations of the subject to the object are clarified most effectively by the schematic of a functional circle (see Fig.3).  It shows how subject and object are each nested the one in the other and form a whole conforming to a plan.  What is more, if one includes the fact that a subject is relayed to the same object or diverse objects, one thus obtains a first glimpse of the first fundamental principle of the doctrine of the environment: all the animal subjects, the most simple like the most complex, are nested in their environments with the same perfection.  To the simple animal there corresponds a simple environment, just as to a complex animal there corresponds a richly articulated environment.

We now place the tick in the scheme of the functional circle as subject and the mammal as its object.  It appears that three functional succeed each other conforming to a plan.  The sebaceous follicles of the mammal form the bearers of perceptual signs in the first circle, for the excitation of the butyric acid provokes in the perceptual organ specific perceptual cues which are exteriorised in olfactory perceptual signs.  The processes take place in the perceptual organ provoking by induction (the nature of which is unknown to us) a corresponding impulse in the motor organ and which provokes the release of the legs and freefall.2First reflex: fall upon prey. During the fall, the tick gives to the hairs that it encounters the motor sign of collision, a sign which provokes on its side a tactile perceptual sign and through which the olfactory perceptual sign of the butyric acid is extinguished.3Second reflex: confirm that one has attained the prey. The new perceptual sign provokes an initial wandering until the first parcel of naked skin is encountered, relayed by the perceptual sign of heat, following which perforation begins.4Third reflex: find the optimal place for perforation.

It is without doubt a question here of three reflexes taking turns in relay and which are always provoked through physical or chemical actions capable of objective verification.  Yet he who contents himself with this confirmation and supposes that the problem is resolved has seen nothing.  What is in question is not the chemical excitation of the butyric acid, nor even that the mechanical excitation (provoked by the skin), nor the skin’s thermal excitation.  Rather the question is solely the fact that amongst hundreds of actions which emanate from the properties of the mammal’s body, there are only three that become for the tick the bearers of a perceptual sign – why exactly these three and no other?

We do not have here a matter of an exchange of forces between two objects; rather it is a question of relations between living subject and its object: and they take place on an entirely different plane, namely between the perceptual cue coming from the subject and the excitation coming from the object.

The tick remains hooked without moving at the end of a branch in a clearing.  In this scenario, there is given to it the possibility of falling onto a mammal that happens to pass.  From all that surrounds it, not one excitation reaches it.  It is only the approach of the mammal, the blood of which is necessary for the begetting of its offspring.  And it is at this moment that the most marvellous thing is accomplished: of all the actions which emanate from the mammal’s body, there are only three which become excitations, and these in a determined order of succession.  In the boundless world that surrounds the tick, three excitations burn like luminous signals coming from the darkness and functioning for the tick as signposts, which lead to its goal with certitude.  In order to render this possible, outside of its body with its receptors and effectors, the tick has been provided with three perceptual cues.  And, through these perceptual signs, the course of its activities is so strictly prescribed that it is only capable of generating entirely determined motor signs.  The entire richness of the world surrounding the tick shrivels and transforms into a meagre product, composed in its essence by solely three perceptual signs and three motor signs: this is its environment.5Readers of Heidegger may recognise in this the infamous statement in the 1929-30 Freiburg lectures on metaphysics that “the animal is poor in world”. Cf. also “Welt ist immer geistige Welt. Das Tier hat keine Welt, auch keine Umwelt“: Heidegger, Einführung in die Metaphysik (Tuebingen: Niemeyer, 1976), 54. The poverty of the environment conditions however the certitude of its activity; and certainty is more important than richness.

From the example of the tick it is possible to deduce, as will be seen, the fundamental principles of construction of environments which apply to all animals.  But the tick possess yet another very curious aptitude which offers us a more profound glimpse of environments.  It is immediately clear that the happy chance that causes a mammal to pass beneath the tick’s branch is extremely rare.  The great number of ticks watching in the bushes do not compensate for this inconvenience in a way which could assure the perpetuation of the species.  It is necessary to add to that the capacity of the tick to live for a very long time without food in order to increase it’s the probability that its prey crosses its path.  And the tick possesses this capacity in extraordinary proportions.  At the Zoologisches Institut Rostock they have maintained ticks alive which lasted 18 years without eating.  The tick can attain 18 years; we humans cannot.  Our human time consists in a succession of instants, that is very brief periods at the heart of which the world shows no change.  During the duration of an instant , the world holds itself immobile.  The human instant endures 1/18th of a second.6Here von Uexküll makes a reference to the way cinema reels (a quick succession of stills) furnish proof of this fact, in a relatively long note that we do not translate.  Cf. Cinéma-I et II by G. Deleuze.

[…] the duration of an instant changes according to different animals, but whatever the number we put forward for the tick, the capacity to cope with an environment which does not change in 18 years finds itself outside the domain of all possibility.  Consequently we admit that the tick finds itself during its waiting time in a state of which appears to it as sleep, a state which interrupts our own lives during a few hours.  Save that, in the tick’s environment, during its waiting time, time is not suspended for hours but for a great number of years, and becomes efficient when the “butyric acid” cue wakes the tick to a new task.

What have we gained by this knowledge?  Something very significant.  The time which envelops every event seems to us to be the sole objective thing that is established faced with the changing variety of its contents, and now we see that the subject dominates time and its environment.  Although we have said until now: without time, there can be no living subject, we must say from now on: without a living subject, there can be no time.

[…] the same thing applies for space: without a living subject, there can be neither space nor time.  Biology has gained by this a definitive union with Kant’s doctrine that it can exploit scientifically in the doctrine of the environment, placing the accent of the decisive role of the subject.


[*] The translation is relatively free and seeks to emphasise this text’s import for the work of Heidegger, Deleuze and Agamben by steering the translational bias towards a philosophical terminology.  E.g. I use “sign” to represent “Merkmal” and “Wirkmal”.  In the interests of time, I have not included all of von Uexküll’s footnotes.

  • 1
    A reflex initially designated the uptake and the return of a light beam by a mirror. Applied to living beings one understands by reflex the uptake of an exterior stimulus by a receptor and the response by the effectors of the living being, activated by the stimulus. Thus is this transformed into a nervous excitation which must pass numerous stages between receptor and effector.  The route thus travelled shall be called the reflexive arc.
  • 2
    First reflex: fall upon prey.
  • 3
    Second reflex: confirm that one has attained the prey.
  • 4
    Third reflex: find the optimal place for perforation.
  • 5
    Readers of Heidegger may recognise in this the infamous statement in the 1929-30 Freiburg lectures on metaphysics that “the animal is poor in world”. Cf. also “Welt ist immer geistige Welt. Das Tier hat keine Welt, auch keine Umwelt“: Heidegger, Einführung in die Metaphysik (Tuebingen: Niemeyer, 1976), 54.
  • 6
    Here von Uexküll makes a reference to the way cinema reels (a quick succession of stills) furnish proof of this fact, in a relatively long note that we do not translate.  Cf. Cinéma-I et II by G. Deleuze.


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