Theoretical biology by Uexküll, Jakob von, 1864-1944; Mackinnon, Doris L. (Doris Livingston)
This is especially necessary in the case of carnivorous animals ; rats, for instance, will immediately devour their own legs, if the sensory nerves to these have been severed.
Moreover, we must learn to regard the function-rule as a real natural factor, and attempt to investigate its effects in all subjects.
Even the "psychoid,” introduced by Driesch into natural science, is to be understood in this sense. The psychoid is an objectively active rule, which we must observe in operation. The word psychoid indicates that here we have to do with a creation by the psyche, for a super-spatial law comes in, not belonging to the body, but controlling it. Can it be that in the function-rule we have come upon something that speaks for the existence of an animal psyche ? A something that justifies the psychologists in setting their science on an objective basis ?
I do not think that such an assumption is justified. There can be no doubt that there are super-spatial rules to which in the last instance the control of even the animal body is assigned. But knowledge of these rules, just as of those governing the animal body itself, must be referred to the laws of our own mind : and the term “ psychoid ” may easily mislead us into supposing that we have here the proof of an apperception by the animal subject. This is not the case. All we can make sure of is the operation of a rule controlling the material of the central nervous system. We have absolutely no knowledge as to whether that is apperceived by the animal.
To appreciate rightly what the effector organs perform in the function-circle, we must consider in more detail the laws that govern our human implements. Hitherto we have considered only our unified tools (such, for instance, as the ladder), and shown that they have a framework constructed in accordance with a function-rule, which fits them for a counter-action in support of our human activities — in this case, the act of climbing.
In comparison with the general rhythm of the impulses which controls the whole life, the beat-rhythm is very insignificant, for it plays an important part only in the higher animals. A certain beat, it is true, can be observed in all forward movements by animals, because, in these, antagonistic movements of the limbs release one another in regular alternation. But there is nothing to indicate that the beat according to which these movements are set going, is fixed in the interior. On the contrary, the ease with which the limbs of the animal adapt themselves, in their to and fro movement, to the difficulties presented by the ground, depends on the lack of an internally fixed beat. As a rule, the free extension of the limbs takes place quicker than the pushing back of the ground, by which the body is driven forward.
The rhythm of the gait is, in most cases, so well adapted to the condition of the ground, because the excitation flows to the "antagonist," only when that is actually on the stretch. That happens, however, only when the " agonist " has contracted, and its representatives have been " locked " against excitation, while those of the extended antagonist are " unlocked."
The rate at which the extension and contraction in the muscles of the limbs alternate, depends in considerable degree on the obstacles on the path at the time, obstacles which the muscles must overcome by their contraction. If an internal beat were trying here to regulate the movements, this would only add to the difficulties.
We find an interiorly determined beat only in those effector organs that have always the same obstacle to overcome, such as the hearts of vertebrates, the margin of the umbrella of jelly-fishes and the wings of insects. The hearts of invertebrates move according to the general law of tension ; their beat, therefore, is not in constant dependence on the amount of blood they contain. The stroke of the wing in a bird is regulated all the time by the receptors, while in insects it is only the beginning and the end of the rhythmical wing-beat that depend on these ; the rhythm itself is quite automatically exerted from the wing-muscle centres.
The effector organs which preserve their own beat-rhythm have for this an arrangement of their own, which is expressed in the so-called "refractory period." The refractory period rhythmically lowers to zero the threshold-value for the regular waves of excitation flowing to the points where the nerves enter the muscles. In what the arrangement consists has not yet been ascertained.
We must try to expand the far too narrow idea of a subjective plan dwelling within all organisms which we involuntarily set in the place of its direct activity. We must take a general view of the sphere of that plan's influence as a whole. And then we shall perceive that the plan is able to shape relations in time exactly as it can shape those in space, so that it cannot be transferred to a point, limited in time and space, within the germ. The impulse-systems, which we may call subjectplans, or, briefly, subjects, in their arrangement control the time-relations, not only during the genesis of the organism, but also throughout the rest of its life. Youth and old age, sleeping and waking, the period of sexual maturity, — these are just as firmly linked as is the arrangement of the limbs in the body.
In contrast to the doctrine of adaptation, which places time outside the life of the organism, and regards it as the actual former of the species, the theory of congruity regards time as a factor under the control of the organising power.
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