Chapter I: The Concepts of Evolution (1)

The preceding considerations have made it evident that the idea of Evolution has undergone a broadening process since Darwin first brought it before the world. It is necessary to glance briefly at some of the chief phases and the general significance of this process in order to define the extent and intent of the concept as far as science has made such definition possible.

To Darwin himself the struggle for existence was always between the unities represented by complete organisms whether as isolated individuals, or in family, tribal, or national groups. Everywhere in his calculations, appearing unchanged in his results, is found the unknown quantity of variation from ancestral type, the known factors being heredity, and natural and sexual selection in the struggle for existence. Wallace's ideas as to color in birds deprive the theory of sexual selection of one of its most important points of application in Darwin's work. It is, in fact, easy to see that sexual selection cannot neutralize natural selection, that any particular form of sexual selection can arise and finally survive only by a harmony with the direction of natural selection, and that the two must therefore appear, even from any standpoint of freedom of the will, as continually attaining coincidence. It has been said, above, that the struggle for existence was, for Darwin, between the organisms as unities. This consistent position of the specialist has been criticised, from a more general point of view, by Lewes in his essay on the Nature of Life,[96] in which he asserts that we must logically "extend our conception of the struggle for existence beyond that of the competition and antagonism of organisms--the external struggle; and include under it the competition and antagonism of tissues and organs--the internal struggle." "Mr. Darwin," he says, "has so patiently and profoundly meditated on the whole subject, that we must be very slow in presuming him to have overlooked any important point. I know that he has not altogether overlooked this which we are now considering; but he is so preoccupied with the tracing out of his splendid discovery in all its bearings, that he has thrown the emphasis mainly on the external struggle, neglecting the internal struggle; and has thus, in many passages, employed language which implies a radical distinction where--as I conceive--no such distinction can be recognized. 'Natural Selection,' he says, 'depends on the survival, under various and complex circumstances, of the best-fitted individuals, but has no relation whatever to the primary cause of any modification of structure.'[97] On this we may remark, first, that selection does not _depend_ on the survival, but _is_ that survival; secondly, that the best-fitted individual survives because of that modification of its structure which has given it the superiority; therefore, if the primary cause of this modification is not due to selection, the selection cannot be the cause of species. The facts which are relied on in support of the idea of 'fixity of species' show, at any rate, that a given superiority will remain stationary for thousands of years; and no one supposes that the progeny of an organism will vary unless some external or internal cause of variation accompanies the inheritance. Mr. Darwin agrees with Mr. Spencer in admitting the difficulty of distinguishing between the effects of some definite action of external conditions, and the accumulation through natural selection of inherited variations serviceable to the organism. But even in cases where the distinction could be clearly established, I think we should only see an _historical_ distinction, that is to say, one between effects produced by particular causes now in operation and effects produced by very complex and obscure causes in operation during ancestral development.... Natural Selection is only the expression of the results of obscure physiological processes."

The last statement is one to which Darwin himself would certainly not have objected. It is an extension of the principle implicitly involved in all his work and explicitly stated in his later work, although the chief emphasis is laid on outer conditions. The extension of the idea of competition from the outer condition of organisms to the more ultimate physiological unities of organ and tissue is a philosophic gain. It is evident, however, that that for which Darwin is seeking is not a philosophical generalization which shall include outer and inner change under one highest law, but, first of all, the particular causes of particular variation interesting to the specialist in biology. It is made too clear for mistake in "The Variation of Animals and Plants under Domestication" that the uncertainty with regard to such particular forms of cause is the spring of his declaration of our ignorance as to variation. The possibility of an inclusion of lower in higher generalizations he would not deny; though the special laws first occupy his attention. Doubtless, his work is not, as is no man's, wholly free from inconsistencies and contradictions,--which are due, in part, to the fact that every scientific theory is, even in the thought of the individual, an evolution. But the declaration of mystery in the question of variation is not equivalent to a theory of accident, of transcendental mystery, or of some special organic or vital force, such as Claude Bernard especially opposed; it is merely and simply a statement of the mystery of present ignorance. This fact is expressly stated in Darwin's later work. We find, for instance, in the introduction to a letter to the editor of "Nature," written in 1873, the origin of many instincts referred to "modifications or variations in the brain, which we, in our ignorance, most improperly call spontaneous or accidental;" and we have, in "The Variation of Animals and Plants under Domestication,"[98] such passages as the following: "When we reflect on the individual differences between organic beings in a state of nature, as shown by every wild animal knowing its mate; and when we reflect on the infinite diversity of many varieties of our domesticated productions, we may well be inclined to exclaim, though falsely, as I believe, that variability must be looked at as an ultimate fact, necessarily contingent on reproduction. Those authors who adopt this latter view would probably deny that each separate variation has its own proper exciting cause. Although we can seldom trace the precise relation between cause and effect, yet the considerations presently to be given lead to the conclusion that each modification must have its own distinct cause." It is "probable that variability of every kind is directly or indirectly caused by changed conditions of life. Or, to put the case under another point of view, if it were possible to expose all the individuals of a species during many generations to absolutely uniform conditions of life, there would be no variability.... The causes which induce variability act on the mature organism, on the embryo, and, as we have good reason to believe, on both sexual elements before impregnation has been effected." Darwin further considers, in this same book, some of the probable particular causes of variation, as given in climate and food. And it may be remarked, in this connection, that Rolph's criticism of the impossibility of progress under conditions of want is irrelevant as applied to Darwin, since the latter himself says expressly: "Of all causes which induce variability, excess of food, whether or not changed in nature, is probably the most powerful";[99] again: "We have reason to suspect that an habitual excess of highly nutritive food, or an excess relatively to the wear and tear of the organization from exercise, is a powerful exciting cause of variability."[100] Rolph's criticism is probably due to forgetfulness of the fact that Darwin limited the struggle for existence to that of complete organisms with one another, and that, under such a limitation of the conception to external struggle, a condition of want cannot be conceived as necessarily precluding a monopoly of abundance by best-fitted individuals.

Theories with regard to the special outer causes and resulting physiological conditions of variation have been gradually added to, as facts on this score have accumulated. But, as investigation advances, the question is seen to involve all the problems of the intricate chemical and mechanical nature of physiological structure in its manifold forms and degrees of organization. The field stretches out in this direction, under our contemplation, to an indefinite distance; and science appears as yet to have passed only the outer limits of its territory.

It is certain that the comparatively recent science of Physiological Chemistry will have many of the decisive words to say on this score, in the future. "When we see the symmetrical and complex outgrowths caused by a single atom of the poison of a gall-insect, we may believe that slight changes in the chemical nature of the sap or blood would lead to extraordinary modifications of structure," says the great seer of evolution himself.[101]

Among special theories of Evolution, a distinction may be made between: (1) such special theories as aim at biological simplification by reduction of all organic variation to one primary form of cellular process; (2) such theories as are content with less ultimate laws, by which the various ascertained forms of change are included in one general statement not involving special physiological or physical theory but applicable to all forms of life; (3) such theories as aim to give distinctive philosophic expression to a generalization like the last named, including in this statement both psychical and physiological phenomena; and (4) such theories as aim at an ultimate expression of the direction of evolution that shall include the phenomena of life, both physiological and psychical, under one head with all other natural phenomena. To the first class belong only "provisional" hypotheses, among the best known of which are those of Pangenesis, Perigenesis, and the Continuity of the Germ-Plasm. To the second, which are not merely tentative but have a broad foundation in known fact, belongs Haeckel's theory of Inheritance and Adaptation, a theory restated in substance, from independent research, by Eimer, whose ultimate general factors of analysis are the same with Haeckel's, though he deals, beyond these, with special facts and special theories of his own. Phases of the second class often entitle them to inclusion in the third. An example of the third class is found in Spencer's definition, "Life is the continual adjustment of inner relations to outer relations." The fourth and last class includes Fechner's "Tendency to Stability" and Spencer's theory of the rhythm of motion (see his "First Principles"), similar to which are certain ideas of Zoellner, Du Prel, and others; and similar elements to which are to be found in Haeckel's "Plastidule-Theory." In connection with this class, reference may be made to an article by Dr. J. Petzoldt in the "Vierteljahrschrift fuer wissenschaftliche Philosophie" under the title "Maxima, Minima, und Oekonomie," in which, among others, Fechner's views especially are discussed with reference to an ultimate principle of evolution. The first pages on the "Tendency to Stability" in Fechner's "Ideas concerning the Evolution of the Organic" ("Einige Ideen zur Schoepfungs- und Entwicklungsgeschichte der Organismen") are as follows:--

"For the sake of brevity I call relations of position and motions recurring at regular periods, that is after like intervals, in the particles forming a material system or in the centres of whole masses conceived as forming a larger system, 'stable relations.' Among such relations is to be reckoned the condition of rest of the particles or masses in relation to each other, as the extreme case, which we may call the state of 'absolute stability'; while a dissipation of the particles or masses, to infinity, in different directions, constitutes the other extreme of absolute instability.

"We do not speak of 'absolute stability,' but of 'full stability,' in cases where motion still takes place, but this brings continually, in exactly the same periods of time, the same relations of particles or masses, not only as regards position, but also as regards velocity and direction of the motion and change of velocity and direction....

"To absolute and full stability may be added, as third case, that of greater or less approach to full stability, which we may term briefly 'aproximate stability'... and of which we have an example in the chief bodies of our solar system.

"It may serve as a simplification of the consideration of stable relations of motion to remark... that, in an isolated system or one under constant outer conditions, exactly or very nearly the same relations of velocity and direction recur when exactly or very nearly the same relations in the position of the particles or masses return. As regards the velocity, this follows directly from the principle of the conservation of energy; as regards the direction, it is indisputably possible to assume the connection of its recurrence with that of the other relations, although I cannot remember that a direct general proof of this has been found.

"With these introductory specifications in mind, let us assume any number of material particles to be restricted, by forces of some sort, to motion within limited space, and the system either withdrawn from outer influences or under such as are constant; let us, moreover, suppose the system undisturbed by the interference of psychic freedom, or the latter impossible. In such case, certain initial positions, velocities, and directions of the parts of the system being assumed, all following states will be determined by these. And now, if there are among these conditions, either present at the beginning, or attained in the course of the motion, any such as have for their result a return of the same states after a given time, then the motion, and so also the positions of the parts conceived as at first undergoing alteration in form and velocity, will, unless they contain the immediate condition of periodic recurrence, continue altering until those of all the possible states are reached which contain the condition of recurrence; until this point is attained, the system will, so to speak, know no rest. Has the recurrence once taken place within a given time, then it must always take place anew within the same time, because the same conditions are there to determine it. And since these conditions are determinative of the whole course of motion from one recurrence to the next, the same course must be repeated; that is, in every like phase of the period a like state of motion will exist. But this gives us full stability of the system, a change, a deviation from the attained stability being possible only through changes in outer influences, the assumed constancy of which rendered the attainment of stability possible.

"This principle appears at first purely _a priori_; but the assumption should not be overlooked that there are among the conditions determining the motion such as lead to their own recurrence, and this is to be taken for granted, since it is necessary to assume that a system must continue to change until, but only until, the conditions of full stability are attained, in case it is attainable; and that this full stability, when once reached, cannot be again destroyed by the action of the system itself. The question presents itself as to how far calculation and experience permit us to lay down a more general principle.

"In a system in which only two particles or masses, withdrawn from outer influences, are determined to motion by mutual attraction and the influence of a primary impulse in another direction, calculation shows us that, motion to infinity being excluded, the attainment, and indeed the immediate attainment, of full stability is a necessity; and for swinging pendula and vibrating strings it may be calculated, from the nature of the moving forces, that they would remain in a condition of fully stable motion if outer resistance were removed; for, such obstacles present, they pass through an approximately stable condition to one of absolute stability. The power of purely mathematical calculation does not go beyond such comparatively simple cases....

"But if we call experience to our aid, it may be asserted, in accordance with very general facts, that, in a system left to itself or under constant outer conditions, and starting from any conceivable state, if not full stability at least a greater or less approximation to it is reached as final condition, from which no retrogression takes place through the inner workings of the system itself. The tendency to approximately stable conditions appears, or the actual state is attained, according to the measure in which variable outer influences are withdrawn. So that so little is lacking to our hypothesis, that, although it has at this point to make up for the impossibility of perfect demonstration, we are nevertheless justified in laying down the following law or principle:--

"In every system of material parts left to itself or under constant outer influences, so, then, in the material system of the universe, in so far as we regard it as isolated, there takes place, motion to infinity being excluded, a continuous progress from more unstable to more stable conditions, up to the attainment of a final condition of full or approximate stability."

From the union of the principle thus stated and that of the conservation of energy "it follows that no unlimited progress of the universe to absolute stability, which consists in perfect rest of the parts, can take place.... The energy manifested in the universe cannot be altered, in general, in its amount, but only in the form in which it manifests itself." "It cannot be asserted that the attainment of full stability in the universe would be the attainment of an eternal rest, but only of the most perfectly adjusted motions, and therefore such motions as would give rise to no variations.... But a condition which brings with it eternal repetition cannot be reached in finite time."

"To elucidation of this principle of the Tendency to Stability," says Dr. Petzoldt analyzing Fechner's work, "we have only to call to remembrance a number of natural phenomena, such as the ebb and flow of the tide, the circulation of moisture, periodic changes of temperature, and so forth, which exhibit great periods of approximate stability and in which we notice in general no retrogression.

"Not less does the constitution of organisms which are, 'so to speak, constituted dependent upon periodicity of their functions, and so upon stable relations of their life,' serve to confirm the theory. Only the concept of stability must be extended in their case, since not always the same, but only substitutive parts of the organic systems tend towards stability.

"Experience never gives us an example of an isolated system; on the contrary, every system is a part of higher systems. The inner relations of its stability are not conditioned by its own parts only, but also, more or less, by those of other systems, so that the destruction of one part-system is always only in the direction towards the stability of a higher, ultimately of the highest, system; that is, of the system of the universe."

"Thus the teleological principle coincides with the principle of the Tendency to Stability, and at the same time the latter constitutes the link between the former and the law of Causality. Though, in truth, this manner of looking at the matter signifies a generalization of the concept of 'end,' since it defines _all_ stable conditions as ends. The view is justified, however, by the fact that the greatest possible physical satisfaction--for us, the criterion of teleology--is always bound up with the longest possible preservation or slow change of a stable organic condition. The _physical_ Tendency to Stability 'bears with it a _psychical_ tendency to the attainment and conservation of just those conditions' towards which the physical tendency is directed."

Of the fact that Lange "feels the lack of the proof of this 'Tendency to Stability,'" Dr. Petzoldt says: "But how is there a need of proof here? To prove is to refer back to known facts. But what is there in Fechner's remarks that stands in need of such a reference? They simply draw our attention to the result of evolution as a state which bears, in itself, the guarantee of some continuance. Can any one contest this? Is there anything further to prove? It is said that Gauss once remarked that Lagrange's equations of motion are not proved, but only historically stated. The case is exactly the same here. The fact is attested, merely, that evolution ends in a stable condition; and herein lies the pith and the great merit of the theory of the Tendency to Stability."

Dr. Petzoldt criticises, among other things, especially Fechner's concept of approximate stability, in that no distinction is made by the author between three different cases. The first case comprises forms of motion in which periodicity is only approximate, but in which, nevertheless, no retrogression in stability takes place; this case is illustrated by our solar system. The second case comprises forms of motion in which the stability increases up to a certain point, but beyond this, despite relative constancy in outer conditions, decreases again until complete destruction of the system supervenes; an illustration of this form of motion is found in all organisms. The third case comprises forms of motion which we cannot concede to be stable. "For, if we ascribe periodic motion to pendula and musical strings which vibrate in a resisting medium, this is nevertheless a periodicity, which continually changes _in the same sense_, and we certainly cannot say that pendula and strings approach, in a resisting medium, a condition of absolute, through a condition of approximate, stability. We recognize in these vibrations, decreasing in amplitude, merely unstable changes which tend toward a final stable condition,--namely that of rest."

The author finds a further ground of criticism in Fechner's assertion that organisms are entirely dependent upon the periodicity of their functions. Only a part of such functions are periodic. Periodicity is not conceivable without stability, but stability is conceivable without periodicity.

In the process of evolution towards a stable form of movement, Dr. Petzoldt recognizes briefly two factors, "Tendency and Competition."[102] Tendency is defined, in general, as the direction, actual or potential, of material parts or of mental or physical function; competition, as the conflict of tendencies, from which a tendency of a higher order results. "The concept of Competition is, like that of Tendency, to be taken in a general significance. A number of forces which act upon a single point compete. Different mental images, observations, concepts, laws, come into competition, from which result concepts and laws of lower and higher orders. The struggle for existence is only a special case of competition. Though this often ends with the immediate or gradual destruction of systems entering upon it, nevertheless only a middle worth between all the competing tendencies can be ascribed to the resultant. Even the conqueror is, after the struggle, other than what he was before it; a part of the tendency destroyed by him lives on in him, has combined with his original tendency to a resultant. Tendencies can as little disappear without compensation as can forces, whether the compensation consists in a strengthening or in a weakening of others, and the _conservation of competing tendencies_ might be regarded as a further qualitative addition to the law of the conservation of force. Hence, in the examination of the effects of the struggle for existence, the like claim of all tendencies taking part in it is not to be left out of consideration. Each makes its full force felt. But not all attain to competition; of the numerous tendencies bound up in one organism, only a few unite, in the single case, to a resultant, which has a direction towards a definite issue." The less the opposition of competing tendencies of concepts or laws, the less the deviation of the resultant from its components, and the less the change these have to undergo. The higher concepts and laws are, the less are the number of distinguishing marks which they take from all single conceptions; for they are the resultants of very strongly opposed components.[103]

Fechner's views are related to, and, to some extent, dependent upon, certain ones of Zoellner adduced in connection with a consideration of sun-spots.[104] Du Prel, who also acknowledges special indebtedness to Zoellner, attempted in his "Struggle for Existence in the Heavens" ("Der Kampf ums Dasein am Himmel") to demonstrate the fact of a struggle and selection among the heavenly bodies analogous to that claimed for life upon the earth. The title of the book was afterwards changed to "The History of the Evolution of the Universe,"[105] its scope having "grown far beyond the limit of the former title." Du Prel finds one of the chief advantages of an application of Darwinian ideas to astronomy in the fact that, unlike our earth, the heavens in their immensity afford us existing, or to our eye existing, examples of the various stages of their evolution, in nebular mist, comets, suns, fixed stars, planets, rings, and moons,--all subject to processes of development, which we may to some extent observe. In the first chapter of this book, Du Prel says: "The existing condition of the Cosmos with respect to all forms of the Purposeful[106]--whether we regard the realm of the organic or the inorganic--can be looked upon only as an attained, moving equilibrium of forces. Immanent in Nature lies the capacity to develop from chaotic conditions to teleologic forms; for, in the ceaseless play of forces, all other than such combinations are by their nature given over to destruction, while it lies, on the contrary, in the essence of all purposeful combinations to be preserved. In every system of mechanical forces an adjustment of the same must finally be arrived at through the removal of all immanent oppositions." "_It is impossible_ for nature to remain in chaotic conditions." "Every system of forces tends to a state of equilibrium. This is as true of the conflict of images in a human brain, from whose mutual accommodation the resultant of a unified theory of the universe arises, as of oppositions in the social organism, of the conditions of power and civilization of neighboring peoples, of the meteorologic states of the earth, of the mechanical forces of a solar system, or the atoms of a cosmic mist. Every war of the elements ends with an adjustment of ideal justice, for every 'moment' of force has influence proportioned to its power and the duration of its activity."[107]

There is one portion of Fechner's theory as above stated (its metaphysical phases being beyond the scope of the present chapter have not been touched upon) that raises a question which may perhaps appear to have in itself no special significance, but which nevertheless opens up, by its implications, new fields of inquiry, and may possibly lead to further theory. The condition of stability which evolution in the universe as a whole gradually approaches but can never attain to in finite time is declared, namely, to be one not of rest, but of motion. A question might be raised, here, as to the definition of the "infinite time" asserted to be necessary to the attainment of such full stability,--whether the phrase be used in the mathematical or the philosophic sense; and the question would be found, I believe, to involve the unanswerable problem of the finite or infinite character of the universe in space. Of a universe conceived under the philosophic concept of spatial infinitude, obviously no final state as the result of evolution can be predicated, the evolution supposing a progress which, as involving infinite matter, cannot be accomplished in finite time. If we, however, conceive the universe as occupying finite space and undergoing continual evolution as a whole in the direction of equilibrium, it is a question whether the end must not be attained in finite time. For a universe conceived as finite, however immense, there must be a finite number, however great, representing the changes necessary to the attainment of final equilibrium; and if progress in the direction of such equilibrium is of necessity continual, the final equilibrium must be attainable in finite time. The question of the nature of such a state of final, universal stability is bound up with the problem of motion through a perfect void, and of the possibility of the formation of such a void through the concentration of matter. Leaving out of consideration the problem in its metaphysical form, which concerns the possibility of conceiving inter-material space, it may be said that it is not now supposed that the heavenly bodies move through an absolute void; and the existence of any medium opposing resistance, however slight, is a condition rendering impossible the attainment of absolute stability of motion or a full stability which suffers no diminution and is, therefore, in effect, an absolute stability. It may be questioned whether the very nature of motion is not coincident with change, and this with action and reaction, or competition. Such a view would reduce evolution to a single ultimate principle, in place of Darwin's Variation and Selection through struggle, or Petzoldt's Tendency and Competition. We should have left, instead of these, only the final principle involved in moving matter considered in its ultimate parts. The metaphysical problem of the infinite divisibility of matter need not here concern us; the ultimate parts of an organism could not be, however, its organs as Lewes defined them, but rather, from a positive standpoint, the ultimate units recognized by science in cell and cell-parts. We may, indeed, since we know no beginning of motion, legitimately regard all tendency as itself resultant. Just as we cannot separate matter and motion, except by abstraction from reality, so, too, we cannot conceive of motion except as having definite direction; and thus we arrive, by a final analysis, at the ultimate philosophic principles of matter and its motion. I use these terms in no metaphysical sense, but merely as generic terms including under one head specific forms of material combination and the specific forms of motion of their wholes or parts.

The question of the character of a conceived state of final equilibrium may be approached from a somewhat different side, though the emphasis falls, as before, on the solidarity of the universe and the nature of motion as change. We may, for instance, regard the earth as an isolated system whose isolation makes possible the continual progress of the evolution taking place on its surface. But this whole evolution is, on the other hand, dependent upon the light and heat of the sun. Again, the sun is undergoing an evolution whose continuous progress may be regarded as in a certain sense dependent upon isolation; but we see, on reflection, that this very process is the result of the cooling nature of the sun's surroundings, and that it is sending its motion in every direction through space. The moon, which has passed through both the evolution that the sun is undergoing and that which is in progress upon the earth, is now passing through another stage which the earth must reach in time by diffusion of its atmosphere, in case its destruction is not accomplished by some catastrophic event before the arrival of that distant period. Suns and planets, all the heavenly bodies, are sending their influence in every direction through the unfathomable depths of space; and just as the capacity of the earth to be warmed by the influence of the sun involves its reciprocal capacity to act as a cooling medium for that body, so the conditions throughout the universe must be regarded as everywhere interdependent and mutually implying one another. Thus we again arrive finally at a universal action and reaction among the parts of the universe, all motion implying change of the direction of motion. Or, since we may and are, in fact, obliged to regard every direction or form of motion as a resultant,--for of motion as of matter we know no absolute beginning,--even this simple assumption may supply us with the conclusion which we have reached in a more roundabout way. We may regard motion in any direction as counterbalanced by a resistance in every other direction sufficient to produce it in this one; in other words, motion takes place at every instant, in the direction of least resistance, even though this direction may represent, in the next instant, through the action of new "moments" of force, the greatest resistance. Any direction as well as any change of direction implies, then, resistance; resistance is equivalent to the interference of force, or, in other words, to competition; and competition may, at any moment, become catastrophe. The difference between competition and catastrophe is one merely of degree, or rather it is a subjective difference depending upon the point of view of the observer. In other words, all that we can testify to is a certain periodicity of motion, all motion meeting with resistance, the accumulation of which finally induces motion in another sense. Larger periodicities are made up of smaller periodicities, and, according to the point of view taken, any period of such motion may be regarded as an evolution, that which Fechner terms "full" stability being only the maximum towards which motion during that period tends. Absolute stability can be conceived only as perfect rest, whether we conceive it as merely an abstraction, its realization as rendered impossible by the conservation of energy, or whether we conceive it as possible in a universe regarded as finite; an absolute stability of motion is a self-contradiction, and a full stability which knows no retrogression is equally a self-contradiction. Periodicity is, then, all into which the Tendency to Stability resolves itself for nature as we know it.

We perceive, in the actual universe, the fact of a certain imperfect periodicity. This wave form of movement in great and little plays, as Spencer has shown far more elaborately than Fechner, a large part in the universe.

But the evident fact of a present periodicity of imperfect form suggests another possible conception. We are under no necessity to regard the universe as finite either in space or time. On the contrary. We tend naturally to conceive of it as finite after the analogy of particular things which we perceive continually to arise and perish; but as concerns space, we have no knowledge of any limit, and, as concerns time, the conception of any actual beginning or end to the universe as a whole is only the ancient naive idea which science has disproved in showing that neither matter nor motion ever perish. An infinite universe is conceivable, in which not exactly the same but very similar forms, or forms of which the successive ones closely resemble each other though those widely separated may be very dissimilar, continue to arise and be destroyed to all eternity. The conception of a primal nebular mist is not a necessary inference from astronomic phenomena; it is as easy and as logical to regard the various phases of planetary development revealed to us by the telescope as so many phases of an evolution and dissolution continually recurring in different parts of the universe, one extreme of which is represented by the nebular mist, the other by the cold and lifeless remains of planets gradually suffering dissolution as they revolve through space. The greater the immensity of the universe is conceived to be, the nearer our conception of it must approach to this type. But the term Tendency to Stability is misapplied when applied to such infinite and imperfect periodicity--to the motion, thus conceived, of the universe as a whole.

The periodicity in the life of organic species may be compared to the wave-motions of light and heat as distinguished from those of water, the individual representing the single wave-length. The analogy is not, however, intended--to speak with Bacon--as one of nature, but merely as one of mind. And just here it may be questioned whether Fechner may not have been right, after all, in his assertion of the dependency of the organism upon periodicity of function, whether the periodic character of the individual life, dependent, as it must be supposed to be, on adaptation to a medium to some degree resisting, does not sacrifice its stability in so far as the increments of resistance lack uniformity. This is evidently the case in large relations; is it not logically necessary to suppose it so in minute relations, though the fact may not be so evident to the coarse measurement of the senses? Experience seems to prove that an approximate periodicity in larger relations, is most consistent with health; and it must be remembered that the non-periodic relations are subordinated to periodic ones, that not only in the case of waking and sleeping, working and eating, but also in those of rest and labor, a certain uniformity is necessary to the best mental and physical condition. A close observation will, I think, reveal a greater periodicity than was at first suspected; since much of it is of so-called "automatic," "unconscious," or "half-conscious" nature. It is to be noticed, here, that the termination of individual lives is often in the nature of a catastrophe, and a uniform periodicity of individual development and decay cannot be assigned, except in the form of an average that falls much below the figure attained by the thoroughly healthy individual. There is every reason to believe that if we could sleep, rise, eat, bathe, exercise, work, and rest with the regularity of a clock, we should be the better for it physically. But the irregularities outside the province of our will-power render it impossible for us to order our lives in this manner. Nor do we desire to do so. For these very irregularities, as representing greater or less change to which adaptation is necessary, are, in many cases and within certain lines, the conditions and signs of progress; though they may constitute in other cases and beyond these lines--that is, where they are of too great intensity or duration--conditions of retrogression, the imperfection in periodicity becoming catastrophe, which may extend beyond the individual to his offspring. We may thus infer that the final destruction of the individual organism is conditioned by its own progress and the progress of its species, but that on the other hand, when the destruction of the individual is too abrupt, it may mean catastrophe to the species also, or at least to a part of it, through heredity.

Our considerations so far have been of a nature to convince us that not isolation, but a constancy in the continual action of like relatively small increments of force in the same directions, is the condition of steady evolution. The less constant and the larger the increments, the nearer the changes involved resemble catastrophe, though the catastrophes themselves may be regarded in another light as forming part of an evolution of a higher order. The changes the sun is undergoing may be regarded as evolution in so far as the influence of the cooling medium is a constant one. The earth as a whole and in its parts may be regarded as passing through a process of evolution towards full stability in so far as the sun's heat is a constant quantity, the periodic changes of seasons and of day and night the same. The relation would seem, therefore, to be one of time--the time-relation involved in the duration of outer conditions as constant with reference to the period required for the attainment of stability. Thus the sun's influence upon the earth might appear approximately constant to the human individual, but might represent a rapid change in relation to some stupendous and long-continued evolution in some other part of the universe. Considerations which we have already noticed forbid our regarding any conditions of "full" as distinguished from absolute stability as anything other than peculiar states single in the system and thus unenduring maxima succeeded by decrease, although the process may be, with reference to any other particular process, so slow, the retrogression from the culminating point so gradual, as to be, with respect to this other process, inappreciable.

And while we are busied with matters which involve the whole multiplicity of relations in the universe, just a word with reference to cause and effect. Which one of these myriad material parts interacting at any moment shall we single out as the cause of the succeeding state? The solidarity of the universe as far as the complete interdependence of all its parts is concerned is clear to us. It is true we cannot reckon with all factors of the universe at once; and the concept of cause and effect is therefore a useful one. But the cause of anything must be, from a positive point of view, just what the methods prescribed for its discovery in any particular case shows it to be: namely, a factor, merely, in the manifold conditions determining a following state, the removal of which means the prevention of the succession of exactly that state. Which, for instance, shall we regard as the cause of an evil act--the character of a man or the temptation offered by circumstances? The change or removal of either means the change or removal of the act. Neither is complete without the other, and both are involved in the whole complexity of the universe, through heredity on the one hand and the action of nature external to life on the other.

And just here we may glance at Spencer's definition of life as "the continual adjustment of inner relations to outer relations." Though emphasizing an important side of evolution, it is evidently incomplete. Evolution is not only the adjustment of inner relations to outer relations, it is also the adjustment of outer relations to inner relations as well as of inner relations among themselves; or it is a process of mutual adjustment of all the parts engaged in it.

Our analysis, though crude and imperfect, may now be regarded as complete. Our scope will not allow of a more elaborate one. It is fitting, therefore, that we proceed to synthesis. The first matter which presents itself to us, in this connection, is the theory of Heredity and Adaptation mentioned above.

The theory is not a new one, wholly outside Darwin's conception of evolution. The concept of Adaptation represents simply the generalization of all those special causes with which Darwin more particularly occupied himself, and is, in essence, only a proclamation of that universal subjection to natural law which Darwin himself plainly asserted. As such a. generalization it is, however, a useful one; it furnishes us with an expression, for the organic world, of that universal action and reaction through which opposing forces move towards stability by mutual adjustment.

The law of Heredity, again, may be regarded as an organic expression of the more general principle according to which motion that, in the sense defined above, suffers only a minimum of interference, that is, motion which, by a certain equilibrium of mutual relations, is "approximately" or "fully" stable, tends to continue to take place in nearly the same directions, or nearly to repeat itself. It is thus apparent, also, that Heredity is closely related to the more special principle of Habit, or also of Use and Disuse, if only we remember that, whatever the metaphysical truths of Freedom or Determination, the psychical is always accompanied by what may be called equivalents of the physical under natural law. The special laws of Heredity are still enveloped in mystery; I refer, not to that mystery which may be regarded as surrounding all ultimate facts, if we choose to conceive them as expressing or concealing something further unknowable, but to the scientific mystery of ignorance, which time may dissolve. Biologists disagree on this question, the ultimate decision of which must be left to them. Still some general criticism on the results of research in this direction may be allowable from a philosophic standpoint.

The chief point at issue between various theories of Heredity seems to be the degree of importance to be attached to Adaptation: however we may express the question, this is the ultimate form to which it is reducible. Now it is obvious, from the foregoing analysis, that the form of theory which would be most useful to us, if such were attainable, would be one in which the degree of tendency to inheritance as well as the strength of inherited tendency is expressed in terms of the intensity and duration of exercise, use, function, habit, or form of motion or action (however we may choose to term it); and variation is regarded as the resultant of such tendency and change in the environment, or, in other words, deviation from constancy of influence. It may be useful to inquire to what extent such a general theory is authorized by special ones.

We have the testimony of two of the acknowledged greatest authorities--Darwin and Haeckel--as well as that of a score of other biologists, and specialists in related branches, to the inheritance of peculiarities acquired during the life of the individual.[108] Eimer lays especial stress on the fact, long witnessed to by one class of specialists, of the hereditary character of brain-diseases, among which may be reckoned some that are without doubt due to direct influence of the environment.[109] Haeckel and Eimer even instance cases in which mutilation has been inherited.[110] One such instance would be sufficient, in overthrowing the general denial of the inheritance of individual adaptation, to make probable the direct influence of the environment in other cases, the uniformity discoverable in the workings of natural law leading us to suppose that the one instance would not be isolated. It must have weight, too, as an argument, in the judgment of many doubtful cases. Not one such case alone is furnished us, however, but many well-authenticated ones. And it is to be remarked that even Weismann has gradually parted from his original theory, recognizing more and more clearly the element of adaptation in inheritance. It seems open to question, indeed, whether Weismann's theory, in withdrawing the germ-plasm from the direct influence of the environment with which the parent individual is in contact does not exempt it from the universal law of action and reaction. Eimer designates such an opposition as Weismann postulates of the germ-plasm to the rest of the organism as a "physiological miracle," and the artificial line thus drawn between the germ-cells before and after the beginning of development as "opposed to that conformity to law shown in the morphological and physiological unity of living beings."[111] Ancient ideas seldom conceived of a universality of action and reaction; and ancient belief, isolating phenomena, invested each with some special guiding power. This belief was maintained as the conception of a special vital force long after the increasing knowledge of nature had caused it to be abandoned with regard to inorganic phenomena; and the theory of the continuity of the germ-plasm seems to be a survival, with regard to the comparatively unexplored province of Embryology, of the idea of such a force.

The elements of which the organism is composed are not strange essences or entities peculiar to the organic; they are the same with those of inorganic matter, though their combinations differ somewhat from these, both in chemical composition and in the morphological arrangement of the composites. We can easily conceive these differences as cooerdinate with differences of general form and function; but it is inconceivable that the continual assimilation of matter in growth should be at any time without result in function, however comparatively small this result may be in higher forms representing an accumulation of energy from previous conditions. The separation of form and function is an abstraction, as is that of matter and motion; we cannot suppose the connection of particular functions with particular forms,--particular organization,--to be accidental, any more than we can suppose the particular properties of particular inorganic composites and elements to be accidental or these particular properties to be without result in the organic matter into which the particular composites and elements are taken up.

The environment must contain complementary conditions of function in order that the individual may even come into existence and survive at all. The great question is, then, how much is to be allowed for original tendency in primal organisms and how much is to be reckoned to the account of the action of the environment in the course of evolution. Even if we go back beyond the organic, assuming a development of the organic from the inorganic, we must come, in the last analysis, to irresolvable elements whose motion, as distinct and particular action and reaction, must have definite form. If we begin with a supposititious simple organism conceived as lowest,--the primal form to which the name "organism" may be applied,--we must likewise conceive of this as embodying motion distinctive as its form, which may be regarded as concomitant and cooerdinate with that form,--or, that is, as function. The ultimate elements of this organism represent positive factors and the primal organism itself must be regarded as a positive factor (or positive composite) without which the evolution of highest organisms would be impossible. We may, therefore, regard it as in this sense embracing the potentialities of evolution. But are we to regard it as representing potentiality in a further sense--in the sense that, beyond the particular life-motion cooerdinate with its particular composition and form, it represents an independent force that prefigures the whole animate evolution? To such an assumption the analogy--which is something far more than a mere analogy--of Embryology logically reduces us, on Weismann's theory, unless we assume a fixity of species that practically does away with the whole theory of Evolution and returns to the original darkness that on which Darwin threw light. Or, if we leave out of account this analogy and begin with sexual propagation, the problem, on Weismann's theory, is very nearly as difficult. Are we to look upon the conditions involved in the environment as mere negatives and simply developing the positive potentialities of the germ-plasm? If we resolve the environment into its elements, even the ultimate analysis must show it composed of positive factors of matter and motion, each one of which has its full worth in any resultant of incidence. The positivity of these elements takes from the primal germ-plasm any superiority of potentiality; the potentiality lies also in the environment. That the organism is in constant contact with the environment is evident; and that this contact, involving incidence of force, cannot be without result, and result representing a full equivalent of all the factors, is also evident. It may seem as if we could understand human progress, or progress in other species, in the limited province open to direct observation, on Weismann's theory; but evolution as a whole becomes, on this theory, a mystery, and indeed, as Eimer terms it, a miracle. Logical consistency thus tells against the theory; and undeniable exceptions to its fundamental conception, furnished by such authorities as Darwin and Haeckel, raise a further presumption against it, that, taken in connection with the logical inconsistencies noticed, constitutes the strongest probability against its truth.

The general experience of mankind has recognized, in a thousand ways, that the individual is "a creature of habit." The strength of the muscle, the cunning of hand or eye or ear, mental acuteness, and even liability to temptation in any direction, or, on the other hand, moral strength, all are coincident with exercise within the bounds set by the normal of the organ,--that is, within its ability to repair its waste in labor, an ability defined by the food-supply and its power of assimilation; for even the moral struggle that is so great as to exhaust physically ends in a weakness which may represent the very condition of conquest by the temptation opposed, if this present itself again before the system has had time to repair its loss. We may regard this weakness as a lessening of force in one particular direction, the resultant of action deviating in favor of the other of the opposing forces or tendencies manifested in the struggle. In this connection I cannot do better than refer to the "Kritik der reinen Erfahrung" already mentioned, in which the influence of the environment on the individual is minutely traced. The special feature of the work is its entire freedom from the thousand metaphysical implications which have gradually gathered about our philosophical vocabulary and which render it well-nigh impossible to write from any new standpoint without danger of misunderstanding. This perspicuity and exactness are secured by a new vocabulary which may seem at first glance, on account of its unfamiliarity, elaborate and incomprehensible, but which is, when mastered, the greatest possible aid to understanding. Nevertheless, the terminology of the book and the exceeding closeness of its analysis, while rendering it peculiarly valuable to the expert in Philosophy, place it beyond the grasp of the average reader; and Ethics is a science which concerns, not the specialist in Philosophy alone, but all thinking minds.