Popular Science Monthly/Volume 13/September 1878/Monera, and the Problem of Life II
|MONERA, AND THE PROBLEM OF LIFE.|
LET us suppose that we have before us a living spherule of the uniform viscid material of so-called protoplasm. It is seen slowly to push forth, at some part of its circumference, a conical process; and, after a while, it is seen still more slowly to retract the same. We are here brought face to face with the initial and fundamental manifestation of one of the chief properties of life. For, what we are observing is living motion, incipient motility. How is it accomplished? What changes in the protoplasm have given rise to this duplex movement, first of protrusion, and then of recoil, on the part of a peculiar portion of the living material?
When the phenomenon is closely watched in different kinds of monera, it becomes evident that the conical projections are formed by a portion of the protoplasm, in which the bonds of cohesion are in some way being loosened; for the matter flows out into space with a certain pushing force—it liquefies and expands. This view is quickly corroborated by the unmistakable recontraction and resolidification of the material forming the projections, when retrogression is taking place. It is plain, then, that alternate expansion and contraction are the visible elements of motility.
Strange to say, biologists have as yet only realized the importance of the latter, less fundamental part of this twofold process. They have been so struck with the peculiar contractile power, with the seemingly sensitive shrinking exhibited by the living substance, that they have deemed it the most salient and characteristic manifestation of life. To convey this notion, they generally give to the protoplasm the name of contractile substance.
Now, "contractility" may be a very expressive term for the property by which the protoplasm is enabled to accomplish the second part, the retrograde half of motility; but, even thus restricted, it includes too much vitalism to suit our present purpose, which is to link the organic to the inorganic world.
We, therefore, cannot allow our scientific inquisitiveness to be arrested by the interposition of a mere name, or qualitas occulta. We do not wish to make known to others that contraction actually occurs in the living substance, for that is notorious. We wish to ascertain for ourselves how this contraction is effected—whether it is the work of entirely new forces exclusively appertaining to life, or whether it is the mechanical expression of molecular forces, with which we are already familiar in the domain of inorganic activities. Is it a specifically vital force which executes the contraction of motility? Or is it a molecular activity of a known kind which gives rise to vital motion?
This simple question may appear to some very unexciting; yet, upon its answer turns, nevertheless, the entire problem of life; for it is just at this point that the doom of vitalism has to be sealed. Vitalism or evolution: these two conceptions of Nature are incompatible. Vitalism means essentially the era of metaphysical agencies, the sway of extraneous powers coercing a resisting world of stubborn matter. Evolution means the era of inherent efficiency, the interaction of intrinsic powers ever elevating the constant realm of transient existences. It is of great importance, then, not to be deceived with regard to the exact manner in which this decisive vital act, the contraction of motility, is at all times being performed in Nature.
Fortunately, our monera give us plain information upon this point. It can be proved that it is chemical decomposition by which the liquefied and expanded material of the conical projection is caused to assume its former condition and place in space. The living substance contracts because it suffers decomposition, as can be directly witnessed. On the strength of this observation it would be quite legitimate to infer that it must have been chemical composition which also caused the reverse activity—which made a portion of the protoplasm start out from its globular limitation, and form a projection measuring in length in some cases more than three times the diameter of the main body. But we are not reduced to mere inference in this instance, so important to the understanding of vitality. By means of various accompanying appearances we can visibly ascertain that it is really a process of chemical composition which underlies the liquefaction and expansion of motility. This leading property of vitality is brought into actual play by the expansion of a certain substance in course of composition, and by the contraction of the same substance in course of decomposition, expansion and contraction being merely the physical concomitants of a definite chemical occurrence. This is shown on the one hand by the products of decomposition being separated and eliminated under our view, and on the other hand by the combining substances being brought together, and effecting their union during inspection. We have no occasion, then, to appeal to the intervention of any specific force in order to understand motility; that is, to understand it in the same manner as we understand other natural processes not belonging to vitality. We have here evidently only a display of specific chemistry. But, then, chemistry is specific all through down to H2O, CO2, and NH3, and who knows how much further?
Expansion and contraction are, as is well known, no uncommon physical concomitants of mere chemical activity, even without addition or subtraction of masses; and it is of fundamental importance clearly to comprehend that vital expansion and contraction are of the same chemical kind, being due to the intrinsic nature of the compound, not to the mere addition or subtraction of mass.
A part of the protoplasm of a moner expands. Chemical composition of a specific kind has taken place, and now it is the physical property of this peculiar compound to occupy more space than before; then the same part of the moner contracts in consequence of chemical decomposition. It is the physical property of the less complicated organic molecule to occupy so much less space. The mass of the added or separated material fills but a very small part of the entire space of expansion or contraction. The expansion as well as the contraction forms part of the specific nature of those different kinds of protoplasm. The organic substance of the moner, plus the separating molecule, is the expanded material. The organic substance of the moner, minus the separating molecule, is the contracted material. The activities of expansion and contraction are merely the physical expression of the gradual process of composition or decomposition occurring within the living substance; they are marks of the shifting of the special relation existing between the protoplasm and its medium during the transitional stages from one state of equilibrium to another.
The great truth which I wish to make quite evident is, that the specific nature of the acting substance constitutes the real power in motility, and not, as is usually believed, the addition of something from outside.
Vital processes will never become intelligible until it is clearly perceived that all vital efficacy resides in the living substance itself, forms an integral part of its specific nature. Many serious misconceptions are afloat with regard to the source of vital power. Science has as yet scarcely penetrated into the outermost precincts of the laboratory of life. The so-called vital dynamics of the present day are beggarly conceptions when measured against the actual wealth of vital manifestations. All we know is, that if so much pressure, so much heat, etc., will effect a new molecular equilibrium in a certain substance, that substance will return to the medium what it has received from it in reassuming its former state.
Will any one pretend to compute the value of the influences which the living substance in the course of ages has absorbed from its medium, in order to become what it at present is? Yet it is these assimilated, equilibrated influences which constitute its real wealth, its source of power, its store of potential energy, whence all its performances emanate.
In the execution of vital motion matter is to some extent "consumed." During expansion it is consumed—taken up by the expanding substance at the cost of the medium. During contraction it is consumed—taken up by the medium at the cost of the contracting substance.
Now, in conformity with the prevailing one-sided view of motility, which attributes the entire phenomenon to so-called contractility, it is generally supposed that the force displayed during living motion is derived exclusively from the consumption of matter on the part of the medium; and it is also generally supposed that this consumption consists in a process of oxidation. Oxidation, it is said, generates a certain amount of heat; this heat is the real motor power in the case.
It does not much affect the bearings of this view whether the oxidizing material be derived, as some maintain, from the contracting substance itself, or whether, as others think, it be derived from food ingredients. The combustion of matter, with accompanying evolution of heat, is deemed to be the true source of power; and the contracting substance—the muscular fibres in higher animals—are stated to be playing merely the part of machinery.
Thus viewed, the problem of life may be considered altogether hopeless. The organism then represents nothing but a force-directing engine, in which the combustion of compounds previously put together in vegetables constitutes the actual driving force. Vital manifestations, accordingly, can be only due to the action of the force liberated from vegetable compounds and applied to the organic machinery. Poor Science, of all-powerful vitality, thou art very young yet, and amazingly unconscious withal!
The moving substance, the protoplasm, plays just so much or just so little the part of machinery as the steam does in the steam-engine. The substance H2O in a calorific medium from about 32° to 212° Fahr., under ordinary atmospheric pressure, occupies a certain space. In a calorific medium above 212°, under the same pressure, it occupies an enormously larger space. This specific property of filling such different spaces, under these different thermal conditions, is the very source of its power—of that motor power which sets the engine going. Whoever wishes to become fully convinced of the fact that it is not the heat of combustion, but the specific expansibility and contractility of H2O, by which the engine is driven, may just throw, instead of so much H2O, a proportionate weight of Au into the boiler.
If this remark should happen to appear far too commonplace for the purposes of scientific illustration, I can merely state in defense of it that, perhaps, in pondering over its meaning, the reader will find himself initiated into a deeper view of force than is usually accepted.
It is for the sake of a somewhat commensurate appreciation of vitality, of high-wrought molecular organization, that it is necessary, again and again, to point out the might of potentiality intrinsic to matter, the vast and specific stores of force locked up in the peculiar molecular entanglements which constitute our different substances. All forms of matter are essentially magazines of equilibrated energies: inert against such other energies as have no power to disturb their equilibrium, but seething with incalculable commotion against such other energies as have power to disturb their equilibrium.
What H2O is to the steam-engine, the moving substance, the protoplasm, is to the living engine. Machinery is fastened on to both these motor powers exactly in the same manner. The expansion and contraction of H2O give motion to the prearranged and molecularly unyielding levers of the steam-engine. The expansion and contraction of the protoplasm give motion to the prearranged and molecularly unyielding levers of the animal engine. We see the correspondence between an engine and a higher organism is even more complete than is generally conceived by philosophers of the purely mechanical school.
Only, the specific power of the slightly complicated molecule H2O cannot possibly afford any standard for the estimation of the specific power of the immensely more complicated molecule constituting protoplasm. Protoplasm differs from water in proportion to its synthetical wealth. Whatever synthetical wealth may be the symbol of, in its gradations is to be sought the source of all difference in Nature. This is the gist of what chemistry teaches: the work of Nature consists in molecular synthesis. It has required the ceaseless toil of endless ages to build up the molecule of living matter. Let us then value it accordingly, and nevermore view it under the degrading aspect of stolid machinery.
Motility, then, consists in the alternate expansion and contraction of protoplasm, which expansion and contraction are incited by a process of chemical composition and decomposition occurring within the protoplasm. The property of occupying so much more or so much less space, under these different conditions, belongs entirely to the respective organic substances, which alternately fill the larger and the smaller space. The forces which are brought into activity during the process are forces of a known kind, but essentially inherent in the living substance. They are stimulated, not transferred. They are a display of intrinsic power, not an application of extrinsic power. They are not the heat of combustion pushing together or dragging asunder the molecules of the organic substance; they are part of the expression, i. e., of the influence on the medium, of those most specific chemical affinities which synthetical elaboration has ingrained into the constitution of the protoplasm.
If, in contemplating this truth, so positively disclosed by the study of living matter, it should become evident that the display of all other force is exactly of the same stimulated and not transferred nature, then, surely, a great advantage will have been thus gained toward a correct understanding of natural phenomena and their relation to each other.
It would then be clearly perceived that Nature does not consist of so many particles of inert matter, held together or pushed about by a set of mysterious agents; but that it rather consists in the disturbance, the overthrow, and the new formation, of equilibrated states of energies.
I have found myself reluctantly compelled to advance this general statement, in order to fulfill the obligations undertaken in this section. For, how am I to establish the gradual, unbroken development of the organic world from inorganic beginnings, when already in the domain of inorganic activity there are believed to exist so many different modes of force, so many kinds of self-sustained and transferable agents? It is true, the so-called forces, the specific motive activities, by diving into certain substances, are said to be in some unknown way "transformed "or" converted "into each other: so much friction into so much heat, or so much electricity. In this conception the identity of a supposed agent or force is evidently sustained in thought. Struck by the definite proportionality found to obtain between the changes occurring simultaneously in the substratum from which the force is thought to have been transferred, and the substratum to which it is thought to have been transferred, the mind is induced by means of a fictitious entity substantially to connect the changes as such, losing sight of the true substances, of which the changes are in reality mere affections. However much the notion may be formally repudiated, the forces are nevertheless in science still conceived as specific entities; to which the current expressions "correlation of forces, "equivalence of forces," "transmutation of forces," etc., bear sufficient witness.
If friction can become electric force, why cannot heat become vital force? And this is exactly what is generally maintained. If it be the rubbing that is or makes the electricity in the sealing-wax, then, surely, it must be the heat that is or makes the vitality in the hen's egg. This also, but somewhat more reservedly, is at times advanced. So much mechanical force converted into so much electric force, in the former instance, whereby—as easily perceived—the preëstablished specific molecular constitution of the sealing-wax is counted for nothing: so much heat converted into so much vital force, in the latter instance, whereby the preëstablished most specific molecular affinities within the egg-substance are counted for nothing. Is not even the proportionality between the changes entirely limited and quantitatively determined by the nature and state of the manifesting substances?
Whether the forces be conceived as specific entities, as definite modes of motion, or as different affections of matter, the idea of their equivalence and convertibility is just as unwarranted, though not so palpably incongruous, as the idea of the equivalence and convertibility of air-vibrations and sound-perception, of ether-vibrations and light-perception. A certain, even quantitatively definite relation obtains between the intensity of stimulation and the stimulated effect, but that relation is neither one of equivalence nor of convertibility. This fact is universal in Nature, but becomes the more obvious the less the mutually affecting substances resemble each other. It is just as impossible that one kind of force can be converted into another kind of force, as it is impossible for any kind of force to originate out of nothing, or to exist without substratum.
A "force-directing" machine or apparatus corresponds to a well-known intelligible fact. A "force-transforming" machine or apparatus corresponds to something altogether unintelligible. If substances had really any such transforming effect on forces, even then they would themselves constitute specifically intervening powers. But this also is hyperbolical, for it does not adequately express the part which substances actually play in the manifestation of forces.
The now so famous notion of the equivalence and convertibility of forces indicates certainly a desirable attempt to bring under the grasp of Science the subtile balance of energies constituting our phenomenal world, but it partakes still too much of the old metaphysical weakness, under which we are wont to seize the shadow and lose the substance. By admitting molecular affections into the vicious circle of mechanical equivalence, it has, however, imported into it an insuppressibly qualitative element, that sooner or later, by its intense expansiveness, will break the narrowing spell, and open to scientific knowledge new fields of unexpected wealth.
The whole mechanical view of Nature rests chiefly on the supposition that effects are equal to their causes, that they are indeed the causes themselves, metamorphosed in appearance. This notion is radically erroneous, and can never lead to an understanding of reality. Causa non æquat effectum. In Nature there exists nothing corresponding to the so-called efficient causes of science, whether single or plural. The scientific conception of cause is a dynamical fiction, made to suit a realm of phantasmal inertia, in which molecularly imperturbable masses pursue forever an unopposed course in a resistless medium. How can we gain an insight into reality by always mathematizing it away?
In Nature all manifestations are the work of opposition and perturbation; agitation of preexisting states, and subversion of the same. It is in this intrinsic potentiality and mutualof so-called masses that Nature has its being, its subsistence, and its perfectibility. The substrata of reality are not merely ponderable or imponderable vehicles of locomotion; but concentrations of actual and potential energies, thrilling through and through with consonant sensitiveness, reverberating with an accent of their own every commotion from the centre of the skies to the centre of the earth.
The entire result of development is preserved in the synthetical intricacies of matter and ether, the sensible and the supersensible substratum. All developmental achievement is embodied in what we chemically call complexity of composition. The more complex a substance, the greater its intrinsic value, the more specific its inherent power, and the less congruous in consequence its response to outside influences.
We cannot make any considerable progress in the philosophy of reality, of which the understanding of our own life is the consummation, before we have first formally reënthroned into their actual seat of power the sovereign energies, so strangely slighted during the long reign of visionary potentates—the eras of anthropomorphism and metaphysics.
Now that we are avowedly appealing to Nature for knowledge, it behooves us to become natural in our mode of thinking. To fix our attention merely on changes and their relation to each other is to grasp at the shadow of reality. That which changes is in every respect the substance, the potentiality and actuality in the case; and it is essentially its specific molecular constitution which determines the nature of the change qualitatively and quantitatively. The scientifically ascertained, most specific behavior shown by the various substances, with regard to their manifestation of different modes of force, or even of one and the same mode of force, is in itself abundant proof that that which we call forces are merely specific modes of reaction on the part of the various substances.
This somewhat lengthy but indispensable discussion on the nature and seat of force will save us the far greater labor of attempting to account for life by computing the foot-pounds of mechanical energy of which it is supposed to be the transformation; or of seeking a standard for the valuation of brain-power, or any other vital activity, by accurately determining the units of heat obtainable from the substances which exhibit these activities.
"But," it will be asked, "if combustion is in no way essential to the manifestation and production of motility, what part is actually played by the oxygen, which is known to permeate all protoplasm, and which is inhaled in such vast quantities by higher organisms?"
Oxygen is the mighty scavenger in the vital economy, the general purifier and clearer. Everywhere among the crevices and interstices of the vital nexus it lies in wait, seizing upon all stray stuff—waste products of function and unassimilable matter of all kinds—and converting the same forthwith into harmless and eliminable compounds. Besides, the heat evolved during this entirely depurative process helps essentially to compose the calorific medium of the organism. But oxidation is in no manner directly conducive to vitality. Within the organism combustion merely hides away death; does not kindle the flame of life; belongs to the domain of destruction, not to that of construction.
Having thus to some extent prepared the way for a more strictly chemical and physical appreciation of vital phenomena, we will proceed, in the next paper, to inquire by what agencies the chemical composition and decomposition of the living substance are effected.
[To be continued.]