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Truth and Error or the Science of Intellection/Chapter 10

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280979Truth and Error — Chapter X.John Wesley Powell


CHAPTER X

HOMOLOGY
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Extension may be defined as exclusive occupancy of space. The particles having extension exclude others from that extension, and thus extension has also been called impenetrability. The particle having motion changes its position to occupy space vacated; hence, change of position is always exchange of position. As the particles are all in motion at an inconceivable rate of speed, one evacuates its position as another enters.

The idea of a plenum of substance was entertained by philosophers in the early history of civilization. Gradually this was abandoned by many, but lately it has been revived as best explaining the phenomena of the ether, and countenance is given to the hypothesis by the demonstration that molecular bodies have internal motions and interspatial ether.

Space is the relation of extension which particles bear to one another in position, when considered without regard to their incorporation in a higher body. If the particles be not ultimate a medium of smaller particles is intercalated. Space, therefore, is the extension of positions.

While space is the relation of positions, positions and relations must vanish if the extensions vanish. These relations may be relations of direction, or they may be relations of distance, but as particles are in motion the relations of direction are changed. In the same manner the relations of distance may change. Thus the boy and the dog may change relation of direction, when one or both move, and they may or may not change relations of distance at the same time. These space relations do not change by reason of intervening bodies. The boy may be a yard from the dog though a wall intervenes.

When positions are considered as established by incorporation, forms are observed having the relations of the particles established, and these established relations constitute structure and figure; thus form is figure and structure. When space becomes form, extension becomes figure and position becomes structure.

By incorporation particles retain in a qualified degree their space relations; that is, the space relations must be fixed within such limits that the incorporation is preserved, for if dissolution supervenes form relations are dissolved. Still, form relations are not fixed with such rigidity as to prevent internal motion. A body may still remain a body within certain degrees of temperature, passing through stages of bulk by contraction and expansion, but if the expansion is increased beyond the critical point the body is dissolved.

We consider bodies as particles when we consider their space relations, and we consider them as forms when we consider their corporeal relations as units. Habits of thought are formed in such a manner that some bodies are usually considered as particles, while other bodies are usually considered as bodies. By like habits of thought it is customary to consider the solar system, not as a body, but as an assemblage of orbs, for the science of astronomy has not yet successfully attacked the problem of the relation of the solar system to other stellar systems. When a body is considered as an individual in shape and structure, form is presented; but when a body is considered as a community of particles, space is considered. Thus it is seen that what is called space in the relations of particles, is called structure in the relations of form. In this treatise the term space is never used to denote the void—the nothing—but is always used to denote something real; so that space relations are the reciprocals of structure relations.

When we consider stars as such they are bodies, the particles of which are molecules. If we could study them as molecules they would present relations of structure; so we may conceive of such relations, though we cannot actually observe them; but we can observe the figures of the bodies. Stars are embodied into systems when they, in turn, become particles and have space relations to one another; this is structure from the standpoint of the system, but the systems as bodies have form as figure and structure. Here in the celestial realm is found a series or hierarchy of individuals and communities.

When we come to the study of the earth as a body, we find it composed of four particles: the atmosphere, the hydrosphere, the lithosphere, and the centrosphere. When we consider it as a body we consider form and structure; when we consider the spheres as particles their relations are those of space, one above another; thus in the body there is form, in the particles there is position, and that which is position in the particle constitutes structure in the body.

Again the stony crust or lithosphere may be considered as a body when its particles are formations of igneous, aqueous, aërial, vegetal, and animal origin. Then as a form its structure is derived from its formations, which are related to one another in structure.

The formations may be considered as bodies; then the blocks of which they are composed, called rocks, are particles. The structure of the formation is the arrangement of the rocks; the relations of the rocks to one another are relations of structure. We may consider rocks as bodies, and omitting ill-defined granulation and incomplete crystallization and also omitting for the present purposes the consideration of the substances of which the rocks are composed, we may consider rocks as bodies with particles of molecules; then the form of the rock is its structure of molecules; the relation of the molecules to one another in position is structure. Omitting various molecular stages in the hierarchy, we find atoms as the particles of molecules, the molecules having form in figure and structure and the atoms having space in their relations of positions to one another. Thus in the geonomic realm there is found a hierarchy of individuals and a hierarchy of communities.

The sciences of geonomy are divided usually into two correlative groups, called geography, in which five departments are pretty well recognized, namely, ethereal geography, stellar geography, aerial geography, hydrographic geography, and land geography; and geology, composed of five well recognized sciences: chemistry, mineralogy, dynamics, structural geology, and paleontology. What I have called geography is approached from the standpoint of quantitative properties, while those sciences which I have called geology are approached from the standpoint of categoric properties. This division into two groups is well recognized when the one is considered as deductive and the other as inductive, or when the one is relegated to the physical division, the other to the natural history division.

We may consider a plant as a body; then the phytons of which it is composed are particles. A phyton may be considered as a body, then the cells are considered as particles; in turn, the cell may be considered as a body, then its blasts may be considered as particles. Then a blast as the nucleus may be the body whose particles are molecules, and the molecule as a body has atoms for its particles. Thus there is a hierarchy of bodies and of particles in the plant realm in which the bodies have form while the particles have space. We do not aspire to a treatise on botany, but stop to consider only certain facts which are essential to this argument; a consideration of the higher plants will serve our purpose. Certain phytons are modified to become roots, which are the organs devoted to the absorption from the earth of the materials which are to be woven into the plant; other phytons become the stem for support; others the branches for expansion; others the leaves for respiration; others pistils and stamens for reproduction, while others become floral envelopes for their protection. Every group of phytons in the plant, therefore, has a separate function, and is an organ. All of these organs, except those for reproduction, have functions relating to the metamorphosis of the individual; but the floral envelope and seed organs are devoted to reproduction. This development of phytons into organisms and organs leads in the study of botany to the consideration of the homologies of the organs. Reproduction in the plant makes a vast stride from ontogeny to phylogeny. Here we are introduced to the subject of heredity. Plants are multiplied in vast numbers and the offspring inherit likeness from parents; this inheritance is put at usury, so that each heir inherits the entire possessions of the legator, and wealth is multiplied by bequest. Then the legatee places his wealth at usury, and with its increments bequeaths it to every individual who is a legatee: so organs and organisms are developed.

The simplest plants are protophytes and unicellular; but these unicellular bodies are still more highly organized in the higher protophytes when unicellular bodies are connected with one another by vegetal threads which are themselves unicellular bodies metamorphosed by elongation, as in the slimes. The protophytes are simple cellate bodies which multiply by fission, and growth itself becomes reproduction.

The cells themselves are organized into tissues and the tissues are arranged in form as planes and combinations of planes. In combining, the planes are sometimes arranged about stems of trunks. These are the thallophytes. The entire thallophyte is a cell with structural parts as nucleus endoblast, mesoblast and exoblast.

In the thallophytes growth is chiefly marginal to a plane. Reproduction is not a division of the whole plant into new plants, but is a division of only portions of the plant which are organs of reproduction. Spores are thrown off from the surface of the reproductive organ.

Systematic botanists seem to be agreed in placing the bryophytes below the pterodophytes.

In the bryophytes a nucleated cylinder is produced which grows mainly by elongation. Special organs of reproduction appear with many devices for the preservation of the spores and their distribution over the soil. In the nature of these reproductive organs I find evidence of high rank. The leaves also are not mere fronds or expansions of the body, but are highly differentiated leaves.

In the pterodophytes the thallophytic structure in planes is still predominant, but roots are developed, the bodies are of more or less cylindrical form, and thallophytic leaves are often found as fronds. The reproductive organs are more highly differentiated. In some the margins of fronds are reflexed to make seed vessels, in others segments of fronds or entire fronds are transformed and there are other methods of forming seed vessels. In all a great variety of seed vessels are found, all exhibiting comparatively simple transformation; the cellate structure of the entire plant is still preserved, though greatly metamorphosed.

The spermatophytes are the flowering plants. In this sub-kingdom the seeds are no longer mere spores, but are plant bodies with microscopically developed forms. The entire plant preserves the cellate structure, while all the organs of the plant are of cellular structure.

The forms of plants are seriated three times:

First, there is the series through which the individual plant passes. Now the forms exhibited in the individual plant at different stages of growth may be compared with the forms of plants of the same species taken at different stages of growth, and the same results reached without waiting for the growth of one plant.

Second, we may study different species of plants and compare them with some one taken as a standard; but this should be a plant of the highest structure. Then in comparing plants of lower structure with it, it will be found that the stages marked in the growth of the higher plant are represented by stages in the order in which the record has been kept in the higher.

Third, a record has been kept in the tome of geology by which the forms of plants have been recorded, not in the language of symbols, but in the language of the forms themselves as fossils. While knowledge of this record is incomplete, in so far as it has been read, it agrees with the individual records and the class records.

The cell of the plant has a structure consisting of a threefold capsule or wall and a nucleus. The seed of the plant has the same structure with the threefold wall or epidermis and nucleus, and the cellular structure is preserved in the plant itself, which retains its envelope of bark divided into three layers which contain a nucleus. We have already found that the earth has a cellate structure, in the air, the sea, the land, and the nucleus; the elements of this structure we have called spheres or cellates. We call the structural elements of the cell, the seed and the plant, blasts or cellates.

Some plants are single celled. These have many forms, but one form is homologous with another, that is, it is composed of the same structural elements. The cells are compounded into phytons and grow into different forms, but one phyton is homologous with another; then phytons are compounded, and still higher plants are produced which are metamorphosed into different forms; but one higher plant is homologous with another. Phytons being composed of cells are homologous with cells, and higher plants being composed of phytons are homologous with phytons, and thus with cells; that is to say, the discovery of homologies in plants is the discovery of the morphologic elements of which they are compounded. As they are compounded, cells are differentiated, and when they are compounded into phytons differentiated cells make differentiated phytons, then differentiated phytons make differentiated higher plants.

In plants there is another set of homologies in the position of the leaves, which is revealed to us in the science of phyllotaxy.

Metamorphosis is growth and decay. One body cannot grow unless another body decays; one crystal cannot increase in size unless some other yields its particles for that purpose; one plant cannot grow unless molecules of water and other substances are used to constitute the molecule of protoplasm; one animal cannot grow unless some other animal or some plant dies; thus metamorphosis is decay of one and growth of another.

Development which supervenes upon metamorphosis is the production of cooperative organs all necessary to the life, growth and reproduction of the individual, and these organs have different powers, which in physiology are called functions. The exercise of functions is accomplished by metabolism, which is the recombination of chemical particles so that new particles come to take the place of those rejected. In this exchange particles do not lose speed, but all have their directions changed. That which is required for present consideration is that exercise stimulates the exchange. Now, activity of function increases metabolism; total rest from activity retards metabolism, and continued rest will ultimately cause atrophy; thus the form of the animal is transformed, for the slow changes that occur in this manner are transmitted to offspring, and if the offspring continue the process, growth or decay are continued in the next generation, and on through many generations, producing results as varieties and fin ally species, as organs are developed and extirpated.

We have now to consider animals and the organs of which they are composed in the transmutations through which they pass as illustrating the subject of morphology.

There are five great classes of animals: Protozoa, Radiata, Mollusca, Articulata, and Vertebrata. The Protozoans are unicellular or simple combinations of cells. Above the Protozoa, animals are organized on four different plans of structure, but they are all compounded of cells, though many of the cells are greatly modified. In these modifications the cellate structure reappears as a fundamental homologue in every organ of all of the higher animals, and it is still found in the animals themselves. The phytons of plants are the homologues of organs in animals. There may be many phytons serving the same functions in plants, as there may be many organs serving the same function in animals; but in animals, as functions are differentiated, kinds of organs are multiplied and the number of organs performing the same functions is diminished from the lower to the higher organism.

In animals the fundamental homologies are found when we discover that all organs are dermal. We cannot stop here to make an exposition of this subject throughout the whole animal kingdom, but will confine ourselves to one small group of vertebrates, namely, the mammals.

First, there are organs of nutrition, constituting all those that take part in the digestion, secretion, and excretion of food. Second, organs of circulation, by which the food when prepared for assimilation is distributed to the tissues. Third, organs of locomotion, constituting the muscular, tendonous, and osseous systems. Fourth, the reproductive organs. Fifth, the organs of mentation, constituting the nervous system.

The organs of digestion which prepare the food are severally sacs and tubes, and conjointly they constitute a system of sacs and tubes, but in this system locomotion must be accomplished, and hence a muscular system is attached to the digestive system. Thus all the organs of digestion are cellate in that they have the cellate elements, for they are composed of encapsulated parts, or inclosing or inclosed envelopes.

The circulating organs are all found to be cellate as tubes or sacs, one or both. In this system extreme variations are found; in the veins and arteries the tubular structure is carried to its highest development, while in the gall, the liver, and the lungs, the sacate form is observed; while the heart is a muscular organ it is still provided with tubes and sacs.

In the muscular system every distinct muscle has a cellate structure, and they are compounded into groups on the cellate plan. Muscles when considered in phytogeny are found to develop into tendons and tendons into bones; the same development is discovered to a limited degree in ontogeny, so that muscles, tendons and bones are homologous. The cellate structure of bones is conspicuous, for they all have the periosteum and nucleus.

In the reproductive systems both sacs and tubes are found, all of cellate structure.

In the nervous system the differentiation between sacs and tubes is carried to its highest degree. The nerves proper are all tubular cellates. In the lowest units they are cellate, and they are compounded as cellates. In the ganglia they are sacate, and are compounded as sacs. Certain of the ganglia have osseous protection as vertebrae, and every vertebra is a cellate structure as a bone with elaborate differentiation in morphology. The vertebrae that have united to form the cranium are extremely differentiated as morphologic elements, but the most extreme of morphologic elements is found in the organs of sense, every organ having a distinct form, and all preserving the cellate structure.

Then the systems of organs which we have just described are themselves compounded into systems, of which hint has already been given. While this subject is vast and tempting, the purpose is subserved merely by giving a few illustrations; and we must forego systematic treatment. In the mouth there are found elements of the digestive apparatus: the circulatory apparatus, the muscular apparatus, as muscles, tendons, and bones, and perhaps elements for reproductive purposes and certainly apparatus for mental functions in the sense of taste. Perhaps in all parts of the body all the five functions are performed by apparatus provided for the purpose. Finally, the entire animal has a sacate and tubular structure, and is thus a grand cellate of a high order of compounding.

The cellate homologies of the man are repeated in all mammals, while the same facts can be seen in birds, reptiles, batrachians and fishes, for all the pentalogic classes present a vast hierarchy of homologies, which illustrate the theme of morphology. Nor does the subject end with vertebrate morphology, for the theme is illustrated in the homologies found through articulates, mollusks, radiates, and protozoa. That which we find in the pentalogic classes of plants we find also in the pentalogic classes of animals—a vast hierarchy of homologies.

Perhaps the great field yet to be cultivated in morphology is in the study of the articulates, especially among insects. The sudden transformations which they undergo in their life history permit the examination of morphologic stages to such an extent that morphology can be studied with all its multitudinous phenomena, and a wealth of science has already been accumulated as a heritage for the army of scientists necessary to give us a complete account of the insects of the world, among whom are found tribes that vie almost with men in demotic development.

We now see how homologies are extended from atom to organism. There are homologies discovered in the atoms, which has given rise to the theory that the atoms discovered in the seventy substances are not ultimate particles, and it must be remembered that it rests only upon the validity of reasoning from homologies, but that all deductive reasoning is based on homologies; it may, therefore, be impossible to reach an inductive demonstration of the complete homology of ultimate particles, but the deductive reasoning is perfect. Then molecules which cannot be seen and cannot be manipulated as individual, but can be discovered only by chemical apparatus, are found by analysis and synthesis to exhibit many homologies, and the science of chemistry undertakes this enterprise.

The earth is a cellate body, and from facts revealed by astronomy it is confidently affirmed that the stars are cellate bodies. Finally, homologies are found in plants and animals; thus there is a hierarchy of homologies throughout the universe which constitute a continuum, and logically no plane of demarcation can be discovered which constitutes an absolute gap. The continuum is not completely demonstrated by induction, but is abundantly demonstrated by deduction.

Homologies have a high development in the organization of demotic bodies discovered in the animals, especially as they are represented among the higher insects, but more fully illustrated in the organization of human society. The forms of organization are various. In the tribes of the world families are organized into clans, and clans into phratries, and phratries into tribes, and tribes into confederacies. In passing from savagery to barbarism, the clan becomes the gens. In all the multitudinous forms of tribal society, homologies have been discovered. In the family husbands and wives, parents and children are found, and sometimes grandparents and more remote kindred are included. In the gens consanguineal kinship is reckoned in the female line; in the tribe it is reckoned in both male and female lines, and ties of affinity are observed. In the confederacy conventional kinship is recognized, and other homologies exist in multitudinous ways. For example, relative age is recognized in the family, in the clan or in the gens, in the tribe and in the confederacy, and to carry out the homology age is often determined by convention.

In national organizations another set of homologies are founded on those of tribal organization. Thus, in the United States we have the family, the township, the county, the state, and the nationality, and homologous units are found in all civilized governments.

Whenever two or more bodies are homologous they are identical, though they may at the same time be different. Homology in form is thus the reciprocal of likeness in kind, so that homologies fall under the same law with kind, and it may be affirmed that whatever is true of an object is true of its homologue in so far as they are identical, which is but another statement of the law already given in classification, that whatever is true of a thing is true of its class identity. We have seen that there is a vast system of homologies extending throughout the universe, commencing with perfect homology in the simple element; but gradually differences appear, becoming more marked as compounding proceeds and differentiation is more marked, that is, there is successive progress in variation from the simple to the compound, and this variation appears as increasing complexity. As things become compound they also become complex.

In the foregoing chapters an attempt has been made to show the relation which exists between extension and unity, position and plurality, space and number, form and kind, together with metamorphosis and metalogisis. Now it remains to show the relation between organism and class, together with a general statement of the relation between morphology and classification. It has been shown that a class is a series of kinds, and as a series it is a disjunct group in a more extended series. It has also been shown that a form undergoes a metamorphosis, and that an organism in its history represents a hierarchy of metamorphisms as exhibited in homology. Now, we must observe that through morphology classes are multiplied, for not only are kinds and series classified, but forms are also systematically grouped.

To investigate the structure of plants we dissect them, and find that when the limit of cell structure is reached and molecular structure appears, we are compelled to pass from dissection to chemical analysis. The highest molecule is protoplasm, but the protoplasmic molecule is composed of molecules of still lower orders until atoms are reached, when chemical analysis fails and only logical analysis seems possible.

In investigating the homologies of plants and plant structure we are thrown back upon the discovery of likeness and unlikeness, or, in other terms, of identity and difference; and we reason about plants, as these identities and differences have been discovered. The discovery of these identities and differences is induction, the application of the laws discovered is deduction.

What, then, is the significance of all these facts, and why should we gather them from the highways of morphology but for the lesson which they teach, that all forms of animals, plants, rocks, and stars are traced to the substrate of extension in the particle? Extension traced through all its complicated relations of space, form, metamorphosis and organism is found to be the ultimate substrate of them all.

Many extended particles incorporated in many bodies have relations of position, space, form, metamorphosis and organization, all of which are included under the term morphology. These relations cannot exist by themselves, but can only be considered by themselves, for relations of morphology are concomitant with relations of classification, dynamics and evolution in the concrete world. Bodies can be analyzed only into particles, and the particles still retain their properties, which may be considered abstractly. If I were called upon to nominate the fundamental error in the logic of transcendental philosophy I should name it the failure to recognize the distinction between analysis and abstraction. The failure to see this distinction seems to have led Pythagoras to found a philosophy upon number; it surely led Plato to found a philosophy on form; it seems to have led Aristotle to found a philosophy on force, and without doubt Spencer fell into this error; while it led the Scholastics to found a philosophy upon being, and finally it led the Idealists to found a philosophy upon thought. Thus the five properties of matter have every one in turn been taken as the substrate of a philosophy, and as the substrate was an abstract the philosophies have been abstractions. Metaphysics has been the attempt to found a philosophy upon an abstract unit, but science is the attempt to found a philosophy upon a concrete unit.

In this chapter an attempt has been made to make a summary exposition of the science of morphology, for the purpose of showing the certitudes which inhere in the science as distinguished from the illusions of mythology defended by speculative philosophy. In transcendental metaphysics the realities of the world are held to be phenomena in the sense that they are illusions, and are distinguished from noumena, which are the realities. Science deals with phenomena, and scientific men hold that phenomena are realities and noumena in the sense of occult substrates are illusions. Transcendental philosophy deals with noumena, and holds them to be realities, and deems phenomena to be illusions.

This is the issue between science and speculation, and the contest is war to the knife of logic against war to the blade of dialectic; but the knife has form, while the blade has void.

In science one noumenon is space, the reciprocal of form; the corresponding noumenon in metaphysic is space as void. Void space is a natural fallacy to men in savagery, while yet the presence of the ambient atmosphere is unknown, and the surface of the earth seems to be an empty theater for breath, wind, and storm existing as disparate bodies having a ghostlike existence. Having imagined an empty space, it still continues to exist in mythology as a void for the theater of gravity, heat, light, electricity and magnetism, after the air itself has been discovered and understood by all civilized men. Now that this notion is dispelled there is no void within the ken of man. All known interspaces have been resolved into forms. If in the depths of the infinitesimal void spaces exist between the particles of ether, it may be well to await their discovery ere we characterize them by assigning properties to nothing.