The Physical Basis of Mind / Being the Second Series of Problems of Life and Mind.

by George Henry Lewes

ORGANISM AND MEDIUM.

53. But we have only one half of the great problem of life, when we have the organism; and it is to this half that the chief researches have been devoted, the other falling into neglect. What is that other? The Medium in which the organism lives. Every individual object, organic or inorganic, is the product of two factors:—first, the relation of its constituent molecules to each other; secondly, the relation of its substance to all surrounding objects. Its properties, as an object or an organism, are the results of its constituent molecules, and of its relation to external conditions. Organisms are the results of a peculiar group of forces, exhibiting a peculiar group of phenomena. Viewing these in the abstract, we may say that there are three regulative laws of life:—(1) The Lex Formationis—the so-called nisus formativus, or “organizing force”; (2) the Lex Adaptationis, or adaptive tendency; (3) the Lex Hereditatis, or tendency to reproduce both the original form and its acquired modifications. We have always to consider the organizing force in relation to all surrounding forces—a relation succinctly expressed in the word Adaptation. Just as water is water only under a certain relation of its constituent molecules to the temperature and atmospheric pressure—just as it passes into other forms (ice or steam) in adapting itself to other conditions; so, likewise, the organism only preserves its individuality by the adjustment of its forces with the forces which environ it.

54. This relation of Organism and Medium, the most fundamental of biological data, has had a peculiar fortune: never wholly unrecognized, for it obtrudes itself incessantly in the facts of daily experience, it was very late in gaining recognition as a principle of supreme importance; and is even now often so imperfectly apprehended that one school of philosophers indignantly rejects the idea of the Organism and Medium being the two factors of which Life is the product. Not only is there a school of vitalists maintaining the doctrine of Life as an entity independent both of Organism and Medium, and using these as its instruments; but there is also a majority among other biologists, who betray by their arguments that they fail to keep steadily before them the fundamental nature of the relation. Something of this is doubtless due to the imperfect conception they have formed of what constitutes the Medium; instead of recognizing in it the sum of external conditions affecting the organism—i. e. the sum of the relations which the organism maintains with external agencies,—they restrict, or enlarge it, so as to misapprehend its significance—restrict it to only a few of the conditions, such as climate, soil, temperature, etc., or enlarge it to embrace a vast array of conditions which stand in no directly appreciable relation to the organism. Every one understands that an organism is dependent on proper food, on oxygen, etc., and will perish if these are withheld, or be affected by every variation in such conditions. Every one understands that an animal which can devour or be devoured by another, will flourish or perish according to the presence of its prey or its enemy. But it is often forgotten that among external existences, all those which stand in no appreciable relation to the organism are not properly to be included in its Medium. In consequence of this oversight we frequently hear it urged as an objection to the Evolution Hypothesis, that manifold organisms exist under the same external conditions, and that organisms persist unchanged amid a great variety of conditions. The objection is beside the question. In the general sum of external forces there are certain items which are nearly related to particular organisms, and constitute their Medium; those items which are so distantly related to these organisms as to cause no reactions in them, are, for them, as if non-existent.[17] Of the manifold vibrations which the ether is supposed to be incessantly undergoing, only certain vibrations affect the eye as light; these constitute the Medium of Sight; the others are as if they were not. Only certain vibrations of the air affect the ear as Sound; to all other vibrations we are deaf; though ears of finer sensibility may detect them and be deaf to those which affect us.

55. “The external conditions of existence” is therefore the correct definition of the Medium. An animal may be surrounded with various foods and poisons, but if its organism is not directly affected by them they cannot be food or poison to it. An animal may be surrounded with carnivorous rivals, but if it is not adapted to serve them as food, or is too powerful to be attacked by them, they only indirectly enter into its Medium, by eating the food it would eat. The analogy is similar with anorganisms and their relation to their media. Every physical or chemical phenomenon depends on the concurrence of definite conditions: namely, the substance which manifests the change, and the medium in which the change is manifested. Alter the medium, solid, liquid, or gaseous, change its thermal or electrical state, and the phenomenon is altered. But although similar alterations in the medium notoriously influence the organism, yet, because a great many variations in external conditions are unaccompanied by appreciable changes in the organism, there are biologists who regard this as a proof of Life being independent of physical and chemical laws; an error arising from their not recognizing the precise nature of organic conditions.

56. To give greater precision to the conception of a Medium it will be desirable to adopt the distinction much insisted on by Claude Bernard, namely, 1°, an External or Cosmical Medium, embracing the whole of the circumstances outside the organism, capable of directly affecting it, and 2°, an Internal or Physiological Medium, embracing the conditions inside the organism, and in direct relation with it—that is to say, the plasma in which its tissues are bathed, by which they are nourished. To these add its temperature and electrical conditions. Bernard only includes the nutritive fluid; but inasmuch as each organism possesses a temperature and electrical state of its own, and these are only indirectly dependent on the external temperature and electricity, and as it is with these internal conditions that the organism is in direct relation, I include them with the plasma among the constituents of the Physiological Medium. Any change in the External Medium, whether of temperature or electricity, of food or light, which does not disturb the Internal Medium, will of course leave the organism undisturbed; and for the most part all the changes in the External Medium which do affect the organism, affect it by first changing the Internal Medium. External heat or cold raises or depresses the internal temperature indirectly by affecting the organic processes on which the internal temperature depends. We see here the rationale of acclimatization. Unless the organism can adapt itself to the new External Medium by the readjustment of its Internal Medium, it perishes.

57. We are now enabled to furnish an answer to the very common objection respecting the apparent absence of any direct influence of external conditions. Let the objection first be stated in the words of a celebrated naturalist, Agassiz: “It is a fact which seems to be entirely overlooked by those who assume an extensive influence of physical causes upon the very existence of organized beings, that the most diversified types of animals and plants are everywhere found under identical circumstances. The smallest sheet of fresh water, every point of the sea-shore, every acre of dry land, teems with a variety of animals and plants. The narrower the boundaries which are assigned as the primitive home of all these beings, the more uniform must be the conditions under which they must be assumed to have originated; so uniform indeed that in the end the inference would be that the same physical causes can produce the most diversified effects.”

Obviously there is a complete misstatement of the argument here; and the excess of the misstatement appears in the following passage: “The action of physical agents upon organized beings presupposes the very existence of those beings.” Who ever doubted it? “The simple fact that there has been a period in the history of our earth when none of these organized beings as yet existed, and when, nevertheless, the material constitution of our globe and the physical forces acting upon it were essentially the same as they are now, shows that these influences are insufficient to call into existence any living being.”[18] Although most readers will demur to the statement that because the material constitution of our globe was “essentially the same” before and after animal life appeared, therefore there could have been no special conditions determining the appearance of Life, the hypothesis of Evolution entirely rejects the notion of organic forms having been diversified by diversities in the few physical conditions commonly understood as representing the Medium. Mr. Darwin has the incomparable merit of having enlarged our conception of the conditions of existence so as to embrace all the factors which conduce to the result. In his luminous principle of the Struggle for Existence, and the Natural Selection which such a struggle determines, we have the key to most of the problems presented by the diversities of organisms; and the Law of Adaptation, rightly conceived, furnishes the key to all organic change.

58. In consequence of the defective precision with which the phrase “Medium,” or its usual equivalent “physical conditions,” is employed, several biological errors pass undetected. Haeckel[19] calls attention to the common mistake of supposing the organism to be passive under the influence of external conditions, whereas every action, be it of light or heat, of water or food, necessarily calls forth a corresponding reaction, which manifests itself in a modification of the nutritive process. He points out the obverse of this error in the current notion that Habit is solely due to the spontaneous action of the organism, in opposition to the influence of external agency,—as if every action were not the response to a stimulus. Corresponding with the fluctuations in the Medium there must necessarily be fluctuations of Adaptation, and I think we may safely assume that it is only when these fluctuations cease that the Adaptation becomes Habit. This is the interpretation of the phrase “Habit is second Nature,” and is very different from the common interpretation which attributes it to the use or disuse of organs; as if use or disuse were a spontaneous uncaused activity.

59. The organism, simple or complex, is, we have already seen, built up from materials originally derived from the External Medium, but proximately from the Internal Medium. This statement, however, requires some qualification, especially in view of the hypothesis that organized substance was originally created such as we now find it, and not evolved from inorganic materials. Whether this hypothesis be adopted, or rejected, we have the fact that the immense majority of organisms now existing—if not all—are products of pre-existing organisms; and therefore organized matter is now mainly, if not solely, formed by organized matter.

We take, therefore, as our point of departure, the protoplasm; this is the first of the three terms of the vital synthesis: Structure, Aliment, and Instrument. The evolution of this is proximately dependent on the pabulum afforded it in the Internal Medium, which is the true nutrient material, and to which what is usually called food stands in an external relation: for between the reception of food and its assimilation by the organite, there is an indispensable intermediary stage, through which matter passes from the unorganized to the organized state. This intermediate is now recognized in plants as in animals. The old belief that plants were nourished directly from the soil and atmosphere can no longer be sustained. The process of Nutrition is alike in both: in both the materials drawn from the External Medium are formed into proximate principles and organic substances. It is daily becoming more and more probable that the inorganic materials, water and oxygen, so freely entering into the organism, never pass directly from the External Medium to the tissues, but have to pass through the Internal Medium where they are changed, so that the water is no longer free, but exists in a fixed state which has no analogue out of the living substance. Only a part of the water can be pressed out mechanically; the rest—that which is already incorporated with the other elements—can only be got rid of in a vacuum and at a high temperature. Oxygen, also, comports itself differently in the tissue; as is proved by the fact that its physiological absorption is markedly different from any chemical oxidation in a dead or decomposing tissue.[20] Be this as it may, we know that organic substances have to be unbuilt and rebuilt in the organism; that the albumen of our food never passes directly into the albumen of our tissues; any more than the milk drunk by a nursing mother will pass into her breasts, and increase her supply, except by nourishing her.

60. In the First Series of these Problems the term Bioplasm was employed to designate this organized part of the Internal Medium. I was led to adopt it as a corresponding term to that of Psychoplasm, by which I wished to designate the sentient material of the psychological medium. There can be little doubt that the term Bioplasm was an unconscious reproduction of the title of Dr. Beale’s work, which I must have seen advertised. I withdraw it now that I have read Dr. Beale’s work, and see that the signification he attaches to the term is almost identical with Protoplasm. In lieu thereof, the term Plasmode (from plasma, anything formed, and odos, a pathway) may be substituted: it represents the nutrient material on its way to form Protoplasm, which is formative material; while the materials formed may be termed Organites and Products: the organite being the cell or cell-derivative (fibre, tube); the products being the gaseous liquid and solid derivatives of vital processes, which are secretions when they form intercellular substance or return into the plasmode and re-enter the vital circle; excretions when they are rejected, as incapable of further assimilation. The liver-cell will furnish an example of each kind of product. The bile, though containing principles serviceable in the chemical transformations, is for the most part excreted; but besides bile, the liver-cell produces starchy and saccharine principles which are true secretions, and re-enter the plasmode.

61. The organite is thus composed of sap, substance, and product; the organism, of plasmode, tissue, and product. A glance at the vegetable-cell shows it to be constituted by the primordial utricle, or protoplasm, the outermost layer of which is condensed into a membrane, or cell-wall, and the cavity thus enclosed is filled with sap. The cell-wall grows as the protoplasm grows, and the protoplasm draws its material from the plasmode. A glance at the blood, the great reservoir of the river of life, shows us plasmode in the serum, and organites in the corpuscles; the one distinguished by sodic salts, the other by potassic salts. The plasmode, or serum, is in a constant change of composition and decomposition, giving up to the various tissue-organites and intercellular plasmodes the requisite materials, and receiving from organites and plasmodes the products of their changes. The serum is fed from the food and the tissues; and it feeds the several plasmodes which bathe the several tissues. Passing into the capillaries, it becomes transformed as it passes through their walls into the intercellular spaces, saturating the acid products of the cell-activities with its alkalies, and furnishing the protoplasms with their needed materials.

62. It will be understood that, although in appearance these stages are sharply defined, in reality they are insensible. But from the analytical point of view we may regard Nutrition as the office of the plasmode, and Evolution as the office of the protoplasm. Although evolution or genesis of form depends on assimilation, it is not a necessary consequence: the plasmode or the protoplasm might preserve such perfect equality in the waste and repair, such complete equilibrium, as not to undergo any development. The ova, for example, which exist in the ovaries at birth are not all subsequently developed; and if with modern embryologists we conclude that there is no replacement of these by proliferation we shall in them have examples of organites remaining unchanged through a period of fifty years.[21] But such an equilibrium is perhaps only possible in complete inactivity.

63. Again, although the office of the plasmode is primarily that of forming protoplasm, I think there is evidence to suggest that it not only does this, but that some of it is used in the direct development of energy, especially heat and electricity. The various forms of starch and sugar taken in with the food or formed in the liver, certainly do not as such enter into protoplasm. The same with alcohol.

64. It is perhaps in forgetfulness of the artificial nature of analytical distinctions that controversies rage respecting what are called intercellular substances and cell-walls. Now that the wall is no longer regarded as an essential constituent of the cell, but as a secondary formation, two opinions are maintained: first, that it is merely a concentration of the external layer of protoplasm; secondly, that it is a product of secretion from the protoplasm. Both positions may be correct. Certainly in some cases there is no other appreciable difference between wall and protoplasm than that of a greater consistence; whereas in many other cases there exists a decided difference in their chemical reactions, showing a difference of composition. Taking both orders of fact, we may conclude that the cell-wall is sometimes part of the organite, and sometimes product: a blood-cell and a cartilage-cell may be cited as examples of each. And this argument applies to the intercellular substance also.

65. The terms plasmode and protoplasm are general, and include many species. There are different plasmodes for the different tissues, so that we find phosphates of soda in the blood-serum, phosphates of potash in the nerve-plasma, phosphates of magnesia in the muscle-plasma, and phosphates of lime in the bone-plasma; having severally to form the specifically different protoplasms of these tissues. Observe, moreover, the gradations of these in respect of their physical state: the blood being the most liquid, the nerve a degree more solid, the muscle still more solid, and the bone almost entirely solid; and since solubility of material is a necessary condition of the chemical changes, we can understand how the blood, the nerve, the muscle, and the bone represent degrees of vital activity: the greater the instability of organized substance, the more active its molecular renovation. Many serious errors result from overlooking the specific differences of protoplasms; among them may be mentioned that very common one of asserting that the ovum of a man is not distinguishable from the ovum of any other mammal, nor the ovum of a mammal from that of a reptile; nay, we sometimes see it stated that the protoplasm from which a mammal may be developed is the same as that which is the germ of an oak. So long as this simply asserts that we have at present no means of distinguishing them by any chemical or physical tests, there can be no objection raised; but it is a serious misconception, which any embryological investigation ought to rectify, to suppose that the ovum is not specific from the first.

66. Between the organites and their plasmodes there is the necessary relation, which corresponds with the relation between organisms and their mediums. Once formed, the organites are arranged side by side, or end on end, into textures or tissues, and these are grouped into organs, every organ being constituted by a collection of tissues, as every apparatus is by a collection of organs, and the organism by the federation of all the parts. We have more than once insisted on the necessity of synthetic interpretation to complete the indications of analysis: which means that no account of vital phenomena is real unless it takes in all the co-operant factors, both those of the organism and the medium. Neglect of this canon vitiates Dr. Beale’s otherwise remarkable labors.