Zoology

Basic Morphologic Types

Johann Wolfgang von GOETHE. From Erster entwurf eine allgemeinen einleitung in die vergleichende anatomic ausgehend von der osteologie,* (= Heft 2 in) Zur morphologie, vol. 1, Stuttgart and Tübingen, 1817 (Heft 1) and 1820 (Heft 2); tr. by V. and M. Hamburger and T. S. Hall for this volume.

CONCERNING TYPES TO BE ESTABLISHED FOR THE FACILITATION OF COMPARATIVE ANATOMY

The similarity of animals to each other and to man is obvious and already recognized in a general way. With regard to particulars, however, it is more difficult to observe, not always immediately demonstrable in detail, often misunderstood, sometimes even denied. Hence, the various opinions of observers are difficult to unify, since a norm against which to test the different parts is lacking, as is a sequence of principles which would also have to be acknowledged.

We have compared the animals to man and to each other, and in this way with much effort, made only detailed advances, but this accumulation of detail has made any kind of survey only more and more impossible. Since, by this method, one had to compare all animals with each and each with all, we realize at once the impossibility of ever achieving unification in this way.

For this reason, there is herewith proposed an anatomical Type—a general image in which the forms of all animals are potentially contained, and according to which the description of each animal would follow a certain order. As far as possible, the Type should be constructed with due regard to physiological considerations. It follows at once from the general idea of the Type that no single animal can be set up as such a canon of comparison; no single one can be the model for all.

Man in his high state of organic perfection must, because of that very perfection, not be set up as a measure for imperfect animals. Rather one should proceed as follows:

First, experience must teach us the parts common to all animals and wherein these parts differ. The Idea must govern the whole, must abstract the general image in a genetic way. Once such a Type has been set up, even though tentatively, then to test it we may employ the formerly customary modes of comparison.

We used to compare: animals with each other, animals with man, human races with each other, the two sexes, the main parts of the body (for instance upper and lower extremities), subordinate parts (for instance one vertebra with another).

All such comparisons can still be made after the Type is established; however, one will undertake them with better consequences and with a greater influence on the whole of science; one will judge what has been done heretofore and assign verified observations to their proper places.

Having established a Type, one precedes to the comparison in two ways: firstly, one describes individual animal species in terms of it. After this has been done, one need no longer compare animal with animal; one merely holds the descriptions against each other and the comparison takes care of itself.

One may also describe some one part throughout the principal genera, and in this manner an instructive comparison is perfectly effected. Both kinds of monographs ought to be as complete as possible to be fruitful; particularly in the latter, several observers might join forces. However, one should first of all agree on a general scheme whereafter the mechanical part of the labor could be expedited by a table on which each observer could base his work and so he would have worked for all, for science. As the matter now stands, it is sad to see that everyone must begin all over again.

General presentation of the Type

In the preceding, we have actually spoken only of mammalian anatomy from the comparative point of view and of possible ways of facilitating its study; now that we undertake the construction of the Type, however, we must look about us more widely in organic nature, because without such a survey we should be unable to establish a general image of the mammals, and because this image, if we consult all nature for its construction, can later be reversely modified in such a way that the images of imperfect organisms can be derived from it.

All fairly well developed creatures manifest in their outward structure three main divisions. Look, for example, at the highly developed insects! Their body consists of three parts which perform different vital functions and which, by their connection with each other and action upon each other, represent organic existence on a high level. These three divisions are: the head, middle, and hind regions; auxiliary organs are found attached to these in different ways.

The head is always anterior in position, is the meeting place of the different senses, and contains the ruling sensory instruments combined into one or several nerve nodes which we are accustomed to call the brain. The middle part contains the organs of the inner vital drive and of unceasing outward motion; the organs of the inner vital drive are less significant because in these creatures every part is apparently endowed with a life of its own. The hindmost division contains the organs of nutrition and reproduction as well as of cruder excretion.

If the three designated divisions are separate and, as often happens, connected only by threadlike tubules, this indicates a perfect state. Therefore, the chief event in the progressive metamorphosis of caterpillar into insect is the progressive separating-off of systems which in the worm still lay concealed under the general covering and were in a largely ineffective, indeterminate state; but now that development has occurred, now that the final and most effective forces operate independently, free motion and action of the creature come into play and, as a result of manifold determination and separation of the organic systems, reproduction is possible.

In perfect animals, the head is more or less distinct from the second division, but by a continuation of the vertebral column, the third is combined with that anterior to it, and enveloped in a common cover. Dissection shows, however, that it is separated from the intermediate system, the chest, by a septum.

The head has the auxiliary organs needed for acquisition of food; they present themselves either as divided pincers or as a more or less connected pair of mandibles. In imperfect animals [e.g., insects—Ed.], the middle region has a great variety of auxiliary organs: legs, wings, and wing coverings; in the perfect animals, (quadrupeds) this middle region has attached to it the middle auxiliary organs: arms or forelimbs. The hind region has no auxiliary organs in insects in their developed stage; however, perfect animals, where the two systems are approximated and crowded together, the most posterior auxiliary organs (called feet) are located at the hind end of the third section, and it is in this fashion that we shall find all mammals organized. Their last and hindermost part possesses, in greater or less degree, a continuation, the tail, which may be considered as suggesting the infinity of organic existences.

Application of the general representation of Type to specific cases

The parts of the animal, their respective forms, their relations, and their special character determine the vital needs of the individual; hence the definite, but limited, mode of life characteristic of each animal genus, and species. If according to the Type we have set up, so far only in a very general way, we examine the different parts of those most perfect of animals which we call mammals, then we shall find that, though the formative sphere of nature is indeed restricted, yet, because of the number of parts and their manifold modifiability, an infinite variety of form becomes possible.

When we know and study the parts accurately, we shall find that their manifoldness of form derives from the fact that this or that part is conceded dominance over the others.

For instance, in the giraffe, neck and extremities are favored at the expense of the body, whereas in the mole the reverse holds true.

From this point of view we are at once confronted by the law that no one thing can be added to any part unless something be deducted from another, and vice versa.

There exist limitations of animal nature within which the formative force apparently moves in a most admirable and almost arbitrary way yet without being in the least capable of breaking the circle or overstepping. The formative drive is here made ruler over a domain which, though limited, is nevertheless well ordered. The balance sheet over which its expenditures are to be distributed is outlined for it. It is free, to a certain degree, to decide how much to turn over to each item. If it wishes to bestow a relatively greater amount on any one part, it is not entirely hindered from doing so, but it is obliged to withdraw something from another immediately; in this way nature can never incur debt or become bankrupt.

With the help of this guide we wish to try to find our way through the labyrinth of animal formation. In the future we shall discover that it extends down even to the most formless organic natures. We wish to test it, first, on form, so that we may later on be able to apply it also to forces. We think, then, of the self-contained animal as a microcosm which exists for its own sake and entirely through itself. Thus, not only is each creature an end in itself; but also, since all its parts are in the most immediate interaction and are all related to each other and in this way continually renew the circle of life, each animal must be considered physiologically perfect. Although parts may appear to be useless viewed externally since the inner correlations in the nature of the animal molded them in this way without consideration of external relations. No part of it is useless when viewed in its internal relations nor, as is sometimes imagined, is it produced by the formative drive arbitrarily, as it were. Hence, in the future, one will not inquire of such parts, for example, as the canines of Sus barbirussa, what do they serve for: but, where do they originate? One will not contend that a bull has been endowed with horns "in order to" butt, but one will investigate how he could have horns with which to butt. The general Type which we shall first construct, on exploring into its parts, we shall find to be on the whole invariable. We shall find the highest class of animals, the mammals themselves, despite their most variable forms, still most conformative.

But now, though our concepts remain constant as regards that which is constant, we must at the same time learn to change our views and acquire manifold mobility as regards that which changes, so that we may be skilled in the pursuit of the Type in all its variability and so that the proteus may nowhere escape.

But if one inquires concerning the causes through which such a manifold capacity for being determined appears, the answer is: the animal is formed by circumstances for circumstances; hence its perfection, and hence its purposiveness viewed externally.

Now, in order to make apparent this idea of an economical give and take we adduce a few examples. The snake ranks quite high in organization; it has a definite head with perfect auxiliary organ, namely the lower mandible joined in front. However, its body is, as it were, infinite, and it can afford to be so because it has to invest neither matter nor energy in auxiliary organs. As soon as the latter appear, when for instance in lizards short arms and legs are produced, then the absolute length must at once contract and a shorter body occur. The long legs of the frog force the body of this creature into a very short form, and the misshapen toad is extended in width according to the same law.

The only remaining question is how far one wishes to pursue this principle, in cursory fashion, through the different natural classes, genera, and species, and make this idea generally evident and attractive by an appraisal of habitus and external character, so that our desire and courage may be stimulated to explore details with attention and pains.

But first the Type ought to be considered with reference to the way in which the different elementary natural forces affect it and also as to how it must submit, to a certain degree, to general external laws.

Water, decidedly, swells up the bodies which it surrounds and into which it penetrates to a greater or less degree. Thus the trunk of the fish, especially the flesh of it will become swollen up according to the laws of the element. Now according to the laws of the organic Type, this swelling up of the body must, no matter what other organs may arise, be followed by the contraction of the extremities or auxiliary organs.

Air by absorbing water, dries things out. Therefore the type which develops in air, will, the purer and the less humid the air is, become that much drier inside; and a more or less lean bird will originate, whose flesh and bony skeleton will be amply covered, and whose auxiliary organs will be sufficiently provided for, because enough material has been left over for the formative force. What is formed into flesh in the fish, is here left for the feathers. Thus the eagle is formed by air for air, by mountain height for mountain height. The swan, the duck, amphibious types, betray their inclination to water already by their shape.

How wonderfully the stork, the sandpiper, indicate both their proximity to water and their inclination to air. This merits bur unceasing attention.

Thus we shall find the effects of climate, mountain height, warmth and cold, besides those of water and ordinary air, to exert a powerful influence in the formation of the mammals. Warmth and humidity cause swelling and produce seemingly inexplicable monsters even within the limits of the type, whereas heat and dryness produce the most perfect and highly developed creatures, however opposed those may be to man in nature and form; for example, lion and tiger. Thus the hot climate alone is capable of imparting some human likeness to even imperfectly organized beings, as occurs, for instance, in monkeys and parrots.

^* Written Jena, 1795.