The Evolution Of Organisms

( Originally Published 1909 )

The General Idea of Evolution. In human affairs what seems to the careless to be quite novel is often revealed to the careful student as the natural out-come of processes which have their origin in antiquity. We see the gradual growth of social organizations, the natural transition from one established order of things to another slightly different position of temporary equilibrium, the trans-formation of one institution into another, and apart from any philosophy of history we sum up what we observe in the general concept of social evolution. It was, indeed, in relation to human affairs that the evolution-formula first became a useful organon, and it is an oft-told tale how it was gradually applied to the heavens above and to the earth beneath and to animate nature in general.' Thence, improved by the using, the formula has returned for reapplication to human history. Now, although there are noteworthy differences between the making of the solar system, the differentiation of the earth, the evolution of living creatures, and the history of societary forms, all cases have this in common, that a process of Becoming leads to a new phase of Being. The study of evolution is a study of Werden and Vergehen and Weiter-Werden. The general idea of evolution is, that the present is the child of the past and the parent of the future.

The evolution-idea is probably as old as clear thinking, which we may date from the (unknown) time when man discovered the year with its marvellous object-lesson of recurrent sequences and realized that his race had a history. Whatever may have been its origin, the idea that the present is the child of a simpler past and the parent of a more complex future was familiar to several of the ancient Greek philosophers, as it was to Hume and Kant; it fired the imagination of Lucretius and linked him to another poet of evolution Goethe; it persisted, like a latent germ, through the centuries of other than scientific preoccupation; it was made actual by the pioneers of modern aetiology men like Buffon, Lamarck, Erasmus Darwin, Treviranus, and Etienne Geoffroy St. Hilaire and it became current intellectual coin when Charles Darwin, Alfred Russel Wallace, Herbert Spencer, Haeckel, and Huxley, with united but varied achievements, won the conviction of the majority of thoughtful men. Since this achievement the fact of organic-evolution has been taken for granted, and there has been a concentration of inquiry on the originative and directive factors in the mysterious process of organic becoming.'

Stated concretely, the general doctrine of descent or organic evolution suggests, as we all know, that the plants and animals now around us are the results of natural processes working throughout the ages, that the forms we see are the lineal descendants of ancestors on the whole somewhat simpler, that these are descended from yet simpler forms, and so on backward, till we lose our clue in the unknown but doubtless momentous vital events of pre-Cambrian ages, or, in other words, in the thick mist of life's beginnings.

Why do we accept this modal interpretation ? The view that things have always been as they are is demonstrably false; the theory of successive cataclysms and subsequent recommencements is hardly thinkable; the only available scientific formulation is the theory of descent. We accept it because it fits the facts we know, because no facts contradict it, because it is congruent with our interpretation of other orders of facts. We can-not verify it as we can verify the indestructibility of matter, the conservation of energy, or the formula of gravitation, but we do know that there is a certain amount of evolution going on under our eyes, and that not confined to Mr. Burbank's garden or the breeders' pens. We extend the idea to the past and find that it works well.

Every one knows how Darwin with sublime patience accumulated evidence of evolution (a) from the distribution of animals in space; (b) from their successive appearance in time; (c) from actual changes observed in domestication, cultivation, and in nature; (d) from facts of anatomical structure, such as homologous and vestigial organs, and (e) from the abbreviated recapitulation of the past which seems to occur in individual development. But magistral as his work was, it did not, and could not, demonstrate the doctrine of de-scent; it simply gave what one may call a cumulative justification by showing how well the formula fitted a vast series of facts. Thus the phrase "evidences of evolution," except as applied to what we actually see going on, is not altogether appropriate. Every differentiation and every adaptation of structure or of function may be interpreted as a product, and may thus become "an evidence of evolution."

Validity of Scientific Interpretation.- It is necessary at this point to interpolate a general consideration. The Theory of Descent tacitly makes the assumption the basal hope of all biology that it is not only legitimate but promiseful to try to interpret scientifically the history of life upon the earth. If any one has good reason for believing that the long process of Becoming, which has eventually led to ourselves and our complex animate surroundings, is altogether too mysterious or too marvellous to admit of successful treatment by ordinary scientific methods, then he denies at the outset the validity of the evolution formula. There is no use going further. Here is the parting of the ways, and there is no via media. The facts of history as the rocks reveal them will remain, but the book is shut for science. The order of Nature remains, but it is no longer the order of scientific intelligibility.

If any one decides on a priori grounds that there is no hopefulness in attempting a scientific analysis of the confessedly vast and perplexing problem of genesis, then let him remain poet or artist, philosopher or theologian. There is no sense in niggling criticism if the scientific method is pre-judged as invalid.

On the other hand, if the scientific attempt at formulating the steps in genesis is legitimate, and if it has made good progress, considering its youth, then let us rigidly exclude from our science all other than scientific interpretations; let us cease to juggle with words by attempting a mongrel mixture of scientific and transcendental formulation; let us stop trying to eke out demonstrable factors by assuming in the same breath alongside of these, "ultra-scientific causes," "spiritual influxes," et hoc genus omne; let us cease writing or reading books with titles like " God or Natural Selection," whose initial false antinomy is sufficient index of their misunderstanding. Not, of course, that we are objecting for a moment to any metaphysical or theological interpretations whatsoever; we are simply stating the commonplace that it is unprofitable to try to talk two languages at once, that we cannot with sanity have scientific formulae mixed up with transcendental formulae in one sentence; and that to place these against one another is to oppose incommensurables and to display an ignorance of what the aim of science is. The great French physiologist Claude Bernard has written, "I am persuaded that the day will come when the physiologist, the poet, and the philosopher will speak the same language and will understand one another." ' We feel sure about the second part of this prophecy, that there will be mutual under-standing; but we cannot even hope for the day when physiologist, poet, and philosopher will speak the same language.

The Actual History as Disclosed by the Palaeontologists.—Returning to the actual history of the forms of life and of course the succession of events remains whether we are scientific evolutionists or not we find that the patience of the paleontologists has been gradually disclosing a majestic pageant, an age-long, ever-changing pro-cession of faunas and floras across the stage of the earth. If we had a series of instantaneous daily photographs of all that has taken place since life began to be, a complete pictorial history of the past would be possible, and evolution would be verified. If even complete remains of past ages had been safely buried in great treasure houses, such as Frederic Harrison has proposed should henceforth be made for the enlightenment of posterity, then paleontology would be an easier business than it is. Then a genealogical tree connecting the Protist and Man would be possible, and we should have under our eyes what is now but a dream a complete record of the past. As it is, we have to eke out our paleontology with hints from comparative anatomy and comparative embryology, which require to be used very carefully.

The fossil-containing rocks have often been compared to a library, with the oldest books on the lowest shelves, but what a library! Spoilt by fire by water, by earthquake, by decay, herb half a shelf awanting and there a series of volumes with most disappointing gaps; pages out of books; words missing in sentences, and the vowels awanting like the points in Hebrew. We are troubled also by palimpsests, one record on the top of another.

We cannot wonder at "the imperfection of the geological record," when we remember how young palaeontology is, how young, for that matter, man is his whole history but a tick of the geological clock; how many areas are still unexplored; how much ground being covered by sea must remain unknown. We cannot wonder that the materials of the history are scrappy when we under-stand that only hard organisms or hard parts are likely to be preserved, that only certain kinds of rocks are suitable tombs, and that many rocks have been unmade and remade many times over. As we walk along the shore and study the jetsam, we see how quickly many of the sea's memoranda are obliterated. The wonder really is that the record is as complete as it is, that from "the strange graveyards of the buried past" we can learn so much about the life that once was.

It is impossible to read even a little about the study of fossils without a thrill of admiration for the patience and insight of the biological archaeologist. He tells us of fossil jellyfishes and of the young stages of Graptolites; he makes from fragmentary specimens a vivid reconstruction of a primitive Vertebrate not much over an inch in length; he makes the great dragons of the prime disport themselves before us; he counts the cuttlefish shells in an Ichthyosaur's stomach and the embryos within the mother; he discovers ancient generalized types, like Phenacodus, uniting widely separate modern orders; he binds birds to reptiles (through the Deinosaurs) and flowering to flowerless plants (through the Pteridosperms); he tracks the transformations of the Ammonites, and works out the pedigree of the horse and the elephant.

General Impressions.—Looking back on the history which the paleontologists have with infinite patience disclosed, we cannot but be impressed by some general facts.

First of all, it is noteworthy that, as Whit-man said, "everything is equally perfect." When we look at a series of human inventions, such as the historical gallery of microscopes at the Paris Ex-position, or a chronological series of bicycles or locomotives, we feel at once that the early stages are crude and clumsy, showing the prentice hand. But this cannot be said of Nature's series. There is no crudity, no suggestion of the half-finished, about the early Graptolites, or Trilobites, about the Ammonites and Nautili, about the Ganoid fishes or the ancient Saurians.

Secondly, no one can think over the evolution of plants and animals without feeling that the fountain of life is practically inexhaustible. All idea of limitation or economy is irrelevant. There is a suggestion of infinite resource. We seem to be in the presence of a great artist who litters his studio floor with priceless sketches. There is no suggestion of pursuing a direct path to some goal. Nature is full of elaborate circuitousness; there are numerous culs-de-sac. If we are to know God through His works, this must enter into our knowledge. We can understand what Tennyson meant when he said, lingering over the crowded life in the brook, "What an imagination God has."

Thirdly, it is undeniable that, in the course of the ages, many types have quite died out, leaving no lineal descendants at all. We visit ancient half-buried cities now the abode of bats and owls, or majestic deserted shrines still sublime in their loneliness, and there comes over us a feeling of awe with the thought that our race is so old that we can sometimes hardly tell what manner of men thronged the now silent streets, or worshipped in these empty shrines. But how is this feeling in-creased when we come to study the remains of races which have been wholly erased from the roll of life lost races whose lineage has come absolutely to an end!

As Gaudry has said: "A host of creatures have vanished; the most powerful, the most fertile have not been spared. There is a sadness in the spectacle of so many inexplicable losses." He was referring, of course, not to extinct species, which are represented to-day by living descendants, but to what we must call extinct types or lost races, such as the Graptolites and Trilobites, the Eurypterids and Pterodactyls. It is true that nothing is ever really lost in this economical world. No scientific student of what is called the circulation of matter can have failed to recognize the deep truth in the reincarnation of Buddha. The grass be.. comes the sheep, the sheep the tiger, the tiger grass again. Atoms that compose part of us may have formed part of a Deinosaur. "The dust of Caesar, dead and turned to clay, may stop a hole to keep the wind away." Yet the physicists' consolation is wan and cold. The fact remains that those particular combinations of elements which we call lost races those particular smiles of creative genius have disappeared as such forever.

In most cases, as far as we can judge, the end came slowly, and not by catastrophes. Races waned and died out; they were not suddenly extinguished. Another striking fact is that while evidences of senescence have been detected in some of the last representatives of dwindling races, there are many cases where a full stop seems to have been put to the history of a stock while it was yet in its prime. Nor is there any reason to think of an elimination of weaklings. As Gaudry says: " While insignificant creatures persist, the primes of the animal world vanish without return." The Ammonites ceased at the time of their finest development; the sea-serpents and the monstrous terrestrial dragons were no weaklings when death gathered them; the flying reptiles, small during the Jurassic, attain large dimensions by the end of the Cretaceous, and then--pass away forever.

We cannot do much more than guess as to the conditions of the extinction of races. Sometimes, perhaps, there were changes of environment, to meet which the plasticity of the creatures was insufficient; sometimes, perhaps, the struggle for existence was to the death, as it may have been between cuttlefishes and trilobites, between Ichthyosaurs and Belemnites; sometimes, perhaps, there were constitutional defects, brought about by over-specialization or the like, such as Lucretius thought of when he pictured races going down to destruction, "hampered all in their own death-bringing shackles."

Sluggish sedentary creatures, walled within their castles of indolence, may have become, as it were, smothered in these. This is suggested by the extreme calcification of certain extinct types like the Cystoids and Blastoids. Others again, like the flying dragons, have perhaps lived too quickly for their constitutions, life's fitful fever proving too much for them. There seems, also, to be a risk involved in being gigantic or in being very highly specialized. As Marsh says, the Iguanodon might have had for epitaph, "I and my race died of over-specialization."

The facts at any rate remain, and they must enter into our picture our conception of Nature. The idea of waste of beauty or fineness of structure is quite irrelevant.

"'So careful of the type,' but no,
From scarped cliff and quarried stone
She cries, 'a thousand types are gone;
I care for nothing, all shall go."'

However we may try to explain it which science never seeks to do in relation to our often very anthropomorphic concepts of End and Purpose the fact remains that Nature is, as we have said, continually painting out her picture, continually breaking her mould.

This, perhaps, was the meaning of that strange stanza in Emerson's "Song of Nature":

"Twice I have moulded an image,
And thrice outstretched my hand;
Made one of day, and one of night
And one of the salt sea-sand."

Perhaps we should infer that a thing of beauty, a smile of creative genius, is sufficient end in itself.

The strange facts as to the entire passing away of animal races, like the parallel facts in regard to particular human races, cannot fail to raise, and ought to raise, a question as to the endurance of our own modern races. It sends a chill to patriotic hearts to think of any human race passing wholly away, and yet such things have been. So far as a race goes on accumulating organic debts (beside which national debts are trifling) and mortgaging in the direst sense future generations, so surely is it doomed to disappear, and justly "in the gathering blackness of the frown of God." Or the other hand, we may strengthen our hands in the assurance that no race is likely to be lost in which it is the loyal endeavor of each pair to leave after them not their worse, but their bettered selves.

Fourthly, the most important impression we get is that of the gradual ascent of life. As the ages passed, higher and higher 1 animals are seen. Fishes were on the scene before Amphibians, Reptiles before Birds.

All theory apart, in the course of the ages life has been slowly creeping upward, finding finer and finer expression, and not along one line only, but along many lines. It is not among backboned animals only that we find the creature reaching toward a greater fulness of life, a greater richness of experience, and an increased freedom from the grip of the environment. Notably there is along many lines an increasing complexity of nervous system, and a correlated liberation of the Psyche.

Let me quote a paragraph freely translated from Gaudry:

"The organic world as a whole has made progress. Suppose a voyager on the oceans of ages; in the Cambrian times his barque meets trilobites, but no fishes; he nears the shore, and there is the silence of death. After long voyaging he finds himself at the end of the Primary era; fishes have replaced trilobites, and on land there is no longer silence. Here is the tramp and cry of reptiles who prophesy the advent of warm-blooded vertebrates. The traveller sails from age to age, and reaches the middle of the Secondary era. Charmingly beautiful ammonites play around his vessel, legions of belemnites mingle with them; ichthyosaurs, plesiosaurs, and teleosaurs follow his track. He goes ashore, and the giant deinosaurs resting on their tails open their huge arms; pterodactyls and other dragons swoop aloft; the first bird tries its wings, and some small mammals show face timidly. Nature, marvellous in the Primary ages, has become yet more marvellous; it has made progress. If our traveller be not fatigued with his long wanderings, he will find in the Tertiary ages the first monkeys and horses, and a thousand other mammals. Later on he will find himself the man artist and poet minister and interpreter of nature —the man who thinks and prays. Truly, the history of the world as a whole is the history of a progressive evolution. Where will this solution lead us?"

Looking back again at the more than plausibly worked out history of backboned animals, we see that the evolution is marked by a progressive differentiation of the nervous system, and that the use made of this is to adapt the organism more perfectly to its environment, and in the higher forms to adapt the environment to the organism. Surely one legitimate deduction so obvious that many miss it is just this, that the primary use of our highly evolved nervous system is not to enable us to construct philosophies, but to empower us to adapt ourselves more perfectly to the inexorables, "moulding the exile to his fate," and to empower us to reach a greater mastery of Nature, to enter into our Kingdom, and to win a firmer control of life. We are all too apt to take an unnecessarily academic view of our destiny.

What do we mean by "entering into our Kingdom" ? We mean that, having gone so far, we must go further in our mastery of natural powers, in our utilization of natural resources, in our revolt against natural selection. Eutopias we want, a replacing of slums by garden cities, a sweeping away of the disfigurements with which we have half-spoiled beautiful places, landscape-gardening on a large scale, instead of the accumulation of ash-heaps. Eutechnics we want, healthful, pleasurable function well distributed, and an ending to occupations which mean miserable lives and untimely deaths. Eugenics we want, an improvement of the human breed, an active pride of race, an enlightened conscience as to marrying and having children, and a more evolutionary education. How much more we want and must have! We have only begun to enter upon our Kingdom.

Factors in Evolution.—When we pass from the modal formula of organic evolution to consider how the process works, we pass from clearness to perplexing uncertainty. Huxley's saying, "If the Darwinian hypothesis (of Natural Selection) were swept away, evolution would still stand where it was," has puzzled some, but it obviously means that while all research strengthens our confidence in the general idea of organic evolution, we are very uncertain as to the actual mechanism. The fact of evolution forces itself upon us; the factors elude us. There can be no dogmatism. The consistent evolutionist knows that he and his interpretation, like the world which he studies, are within the sweep of the evolution process, have been evolved, and are still evolving. He never claims finality of interpretation, for that would be self-contradiction.

Variations : The Raw Materials of Progress.—The first great question concerns what may be called the raw materials of progress the origin and nature of those organic changes or variations on which the possibility of evolution depends. Dar-win started from the broad fact that variability exists, illustrating it chiefly from domesticated animals and cultivated plants; he postulated an ' See Sir E. Ray Lankeater's "Kingdom of Man," 1907.

abundant crop of organic changes, toward tares and toward wheat, and he showed how a process of thinning and singling, sifting and winnowing, would operate upon the ever-growing, ever-changing crop, so that the result was progress.

But all science begins with measurement, and the great step in advance that has been made of recent years is in the dry and tedious, but peremptorily necessary task of accurately recording the variations that do actually occur. Life is so abundant and so Protean that biologists have tended to draw upon the variability account as if there was no limit to it, scarce waiting to see whether their cheques were honored. Without being biologists, simply as clear thinkers, we must feel the unsatisfactoriness of merely postulating variability to meet the demands of particular problems. In ordinary evolutionist discourse, as Mr. Bate-son justly points out, there has been continual use of the argument, "If such and such a variation then took place and was favorable," then ... , a mode of talk which we would ridicule in Paley or Butler, but which we in our inconsistency still tolerate in ourselves. It is obviously our business to be able to say, "such and such variations do occur in Nature, therefore. . . ." But we are now changing all this. The very title " Biometrika " of a new journal is a sign of the times. In hoc sign laboramus. The recording and statistical registration of organic changes that actually occur is rapidly helping us out of the slough of vagueness, in which, to the physicist's contempt, biology has so long floundered. It is too soon to sum up the results of recent studies on variation, but some facts are clear.

(1) Variability is even greater than Darwin sup-posed, and is not less among creatures living in a state of nature than among those domesticated or cultivated forms on which the great master concentrated his attention. Whenever we settle down to measure, to identify, to describe, we find that specific diagnoses are average statements, that specific characters require a curve of frequency for their expression, that the living creature is usually a Proteus. It is true that there are long-lived, non-plastic, conservative types, built, as it were, not for a day, but for all time, like Lingula, and perhaps a score of other well-known organisms, where no visible variability (of hard parts, at least) can be proved even in a million years. But to judge from these as to the march of evolution is like estimating the rush of a river from the eddies of a sheltered pool.

(2) It has become possible to distinguish between minute fluctuations, which seem to be of general occurrence, in which the offspring has a little more or a little less of a given character than its parents had, and discontinuous variations or mutations, in which something new emerges suddenly without gradual stages and with no small degree of perfectness. Using Galton's simile we can picture a polyhedron oscillating or rocking on one of its faces, this would be fluctuation; we can picture it rolling over to a position of equilibrium on another face, this would be mutation.

Though there is some truth in Lamarck's saying that "Nature is never brusque," and though we may justifiably disbelieve entirely in grotesque "Jack-in-the-Box" phenomena, such as Bastian's "Heterogenesis" (e. g., the origin of a large infusorian by the transformation of a Rotifer's egg), which would make Nature magical and irrational, we now know, through the work of Mr. Bateson and others, that discontinuous variations are not rarities. In particular we know through the beautiful work of De Vries on "Evening Primroses and Other Plants," that organisms may give rise to offspring which are distinctively new, and that these are mutations come to stay. Such words as "freaks" and "sports" are not very happy, but they suggest the idea of what Mr. Galton calls "transilient" variations the fact that organic structure may pass with seeming abruptness from one position of organic equilibrium to another. We have, in short, to deal with a Proteus who leaps as well as creeps.

De Vries' Evening Primroses —Let us recall, for a moment, the case of the Evening Primrose (Oenothera lamarckiana), which Professor Hugo De Vries found as an escape in a potato-field at Hilversum in Holland. Its chief interest was its changefulness; it was, so to speak, frolicking in its freedom; it was in a variable mood. Almost all its organs were varying as if swayed by a restless tide of life. It showed minute fluctuations from generation to generation; it showed extraordinary freaks such as fasciation and pitcher-forming; it showed hesitancy as to how long it meant to live, for while the majority were biennial, many were annual, and a few were triennial; best of all, it showed what could hardly be otherwise described than as new species in the making. From this stock, De Vries obtained in a short time half a dozen or more distinct varieties or elementary species, breeding true generation after generation. In short, he was fortunate enough to have found a plant in process of rapid evolution. It is rash to generalize as yet, but other cases of mutation are now being studied, and it may be that in many instances "new varieties are produced from existing forms by sudden leaps." If there are many such cases, the aspect of the evolution theory will have to be changed; we shall attach less importance to the accumulation of minute fluctuations, and we shall not have to lay such a heavy burden on the shoulders of natural selection.

The Organism is a Unity.-(3) It is also becoming more and more evident that the living creature varies, in many cases, as a unity. If there is more of one character, there may be less of another; one change brings another in its train. As Darwin pointed out, there is a "correlation of variation." We see one part varying and we can plausibly say that its changes in a given direction are useful and life-preserving, but meanwhile there may be in the train of this observable variation another which is destined to be of far greater import. Another aspect of the same idea, illustrated for instance by the authors of "The Evolution of Sex," 1 is that changes apparently confined to minute and superficial parts may be, as it were, the correlated out-crop of deeper physiological variations of the whole system or of a large part of the system. As Professor Ray Lankester says,2 "We should, perhaps, more generally conceive of variation as not so much the accomplishment and presentation of one little mark or difference in weight, length, or color, as the expression of a tendency to vary in a given tissue or organ in a particular way. Thus we are prepared for the rapid extension and dominance of the variation if once it is favored by selective breeeding."

Modifications.—Besides variations which spring from within emerging from the penetralia of the germ-cells, where lies the fountain of all lasting organic change there are modifications superinduced from without. They may be defined as changes wrought in the body of an individual during its lifetime, as the direct result of changes in function and environment, which so transcend the limits of organic elasticity that they persist after the inducing conditions have ceased to operate. The peculiarities in our finger prints are variations, but the cahosities on our hands are modifications. The inborn peculiarity of our facial physiognomy is a variation, but sunburning which lasts for years is a modification. These modifications or acquired characters are often of great personal importance and they may also serve as temporary shields or screens for incipient inborn variations in the same direction, but they have not been proved to be of direct importance in the evolution of races, since there is no convincing evidence that they can be transmitted as such or in any representative degree. In short, organic progress is primarily due to changes in heritable Nature, not to changes in Nurture.

Causes of Variations.—As to the causes of variations and mutations we know very little. We must still repeat Darwin's words, "Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part has varied." It is probable that variability is, like growth, a primary quality of living things, and that "breeding true" has arisen secondarily as a restriction. The relation of genetic continuity between successive generations is an economical arrangement which secures relative constancy amid continual flux. In spite of this, however, the Proteus continually asserts itself. There may be, for all we know, a process of growing and varying inherent in the germ-plasm, requiring only an occasional environmental stimulus to keep it agoing. We must remember that the germ-plasm, though marvellously stable in its general architecture, has the instability involved in great complexity. Sur-rounding it there is the very complex, very variable, nutritive environment of the body. In the processes of maturation there is an extraordinarily elaborate shuffling of the cards which we call chromosomes. In fertilization, at the beginning of almost every new life, we see the making of a living mosaic of parental and ancestral contributions, and there is abundant opportunity for new permutations and combinations,

Directive Factors in Evolution.—We must pass now to the directive factors which operate upon the raw material afforded by variability. The only directive factors we know of are included in the terms Selection and Isolation. These are the twin directive genii.

Selection.—The theory of Natural Selection, which Darwin and Wallace first expounded, is very familiar, and admits of brief statement. Variability is a fact of life. The members of a family or of a species are not born alike; some have qualities which give them an advantage, both as to "hunger" and as to "love"; others are relatively handicapped. But a struggle for existence is also a fact, being necessitated especially by the abundance of life and by the changefulness of the environment. Two parents usually produce many more than two children, and the population thus tends to outrun the means of subsistence; more-over, living creatures are at the best only relatively well adapted to the conditions of their life, which are changeful. As the result of this struggle for existence, there is discriminate elimination, the relatively less fit being eliminated before they reproduce. "Of fifty seeds, she often brings but one to bear." The relatively fitter tend to survive and to reproduce, handing on their ad-vantages to their progeny. If advantageous variations are transmitted, if variations in the same direction crop up generation after generation, if there is gradual augmentation of the amount of the profitable peculiarity (through the pairing of similar variants or otherwise), and if the discriminate selection continues consistently, then the process will necessarily work toward the establishment of new adaptations.

Given a sufficient crop of variations and sufficient time, what may a process of selection not effect ?

Conditions of Progress through Selection.—There are two conditions, however; first, that some of the variations continually occurring are in the direction of fitness, and secondly, that the process of elimination, for elimination it comes to, is a discriminate process. Neither of these conditions is to be lightly passed over. The occurrence of variations in a profitable direction is often a great puzzle, which has led some to take refuge in verbalisms, "inherent tendencies to perfection," and the like. Especially when the new departure is not merely quantitative, but qualitatively novel, and exhibited suddenly, is the puzzle great. We have a Mutation Theory, but no theory of mutations. Natural Selection, as some one says, ex-plains the survival of the fittest, but not the arrival of the fittest. As usual, it is a question of the beginnings which gives us pause. And as to the second point, we must be clear that indiscriminate elimination does not count for much in nature's methods. We see the men in the fields thinning or singling turnips. With rapid strokes of the hoe they kill nine and leave a tenth, giving it elbow room, and liberating it from too intense competition. But they do not pause to select out the most vigorous young turnip plant; this would be discriminate selection, which we are familiar with in the more intensive cultivation of the garden. On the whole, the process of thinning turnips is in-discriminate elimination, though, of course, one knows that the survivors are left at regular distances, and so forth, The point is that while this thinning is profitable for the surviving individuals, it does not directly help the race, it does not make for the evolution of superior turnips. So it is in Nature's thinning and singling; it is only consistent discriminate elimination that counts for much.

One hundred and thirty-six English sparrows in America were worsted by a severe storm and were brought benumbed into a laboratory. Seventy-two revived, sixty-four perished. Professor Bumpus made a careful comparison of the eliminated and the survivors with the result of showing that the birds which perished because of the storm were deficient as regards certain qualities in which those that survived were stronger. In other words, this storm, at least, was an agent in discriminate elimination.

Struggle for Existence.—In thinking of the process of Natural Selection, it is of real importance to recognize, with Darwin, that the phrase "struggle for existence" is used "in a wide and metaphorical sense," including much more than an internecine scramble for the necessaries of life including indeed all endeavours for preservation and welfare, not only of the individual, but of the offspring as well. The struggle expresses itself not merely in an elbowing and jostling around the platter, but at every point where the effectiveness of response which the creature makes to the stimuli playing upon it, is of critical moment. It is much more than a long-drawn-out series of family quarrels ending in more room and food for a few surviving members; it may often be more justly de-scribed as an endeavour after well-being. And what may have been primarily self-regarding impulses become replaced by others which are distinctively species-maintaining, the self failing to find realization apart from its family and its kindred.

We may gain some clearness when we notice that struggle is manifold.

(1) It may be between near kin as when a tad-pole eats its brother tadpole, or when the embryos in the dog-whelk's capsule on the shore play the same game, and illustrate cannibalism in the cradle, or when locust devours locust, and rat kills rat. Under this category we have to include the struggles of rival males, as among stags, and the strange struggles of the sexes, as in spiders.

(2) It may be between organisms not nearly related, as between carnivores and herbivores, between plants and snails.

(3) It may be between organisms and the inanimate environment, as between birds and the winter a form of struggle entirely non-competitive.

Or, again, we may distinguish different forms of the struggle according to what is achieved by it —survival from immediate death, a longer life, a more comfortable life, a larger family, a more successful family, and so on.

In regard to the process of elimination, we must carefully notice that it does not necessarily mean that those eliminated come at once to a violent end, as when locust devours locust, or the cold decimates the birds in a single night; it often means simply that the less fit die before the average time, or are less successful than their neighbors in rearing progeny. But whether the eliminative process be quick or slow, gentle or severe, competitive or environmental the result is the same, that the relatively more fit tend to survive. We need not waste time in combating the absurd misunderstanding that fittest means best or highest according to any evolutionary standard; it only means fittest relatively to given conditions. The tape-worm is not exactly what one would call a noble animal, but after it gets settled down in its host it is remarkably well adapted to its own peculiar conditions of material well-being. The golden eagle is a much finer creature than, say, the microbe of grouse disease; but, as things are, the chances of the golden eagle's survival in Britain are much less than those of the grouse-microbe.

There are some naturalists who will not accept the interpretation of the struggle for existence which has been outlined above, which seems on the whole consistent with Darwin's. Thus Professor Ray Lankester writes, it seems to us unwarrantably, "In Nature's struggle for existence, death, immediate obliteration, is the fate of the vanquished." "The struggle between species is by no means universal, but in fact very rare. The preying of one species on another is a moderated affair of balance and adjustment which may be described rather as an accommodation than a struggle." "The 'struggle for existence,' to which Darwin assigned importance, is not a struggle between species, but one between closely similar members of the same species." ("The Kingdom of Man," 1907.) As a matter of fact, Darwin assigned importance to many different forms of the struggle for existence. Even when we take his paragraph headed, "Struggle for life most severe between individuals and variations of the same species; often severe between species of the same genus," we find only five illustrations, and these are not altogether convincing.

Isolation.—Besides selection we can discern an-other directive factor what we call Isolation. One of the early competent critics of Darwin's theory of Natural Selection, Professor Fleming Jenkins, emphasized the difficulty that variations of small amount and sparse occurrence would tend to be swamped out by intercrossing. In artificial selection, the breeder takes measures to prevent this by removing unsuitable forms and by deliberately pairing similar and suitable mates; but what in Nature corresponds to the breeder ? There are several ways of meeting this criticism, but the one that concerns us at present is the theory of isolation, worked out by the late Dr. Romanes, by Mr. Gulick, and others. Attention is directed to the great variety of ways in which, in the course of nature, the range of intercrossing is restricted for instance, by geographical barriers, by differences of habit, by likes and dislikes, which result in assortive mating, by reproductive variations which cause mutual sterility between two sections of a species living on a common area, and so on. According to Romanes, "without isolation, or the prevention of free intercrossing, organic evolution is in no case possible." It has to be confessed, however, that the body of facts in illustration of this thesis is still unsatisfactorily small, though it is interesting to note that each valley in the Sandwich Islands seems to have its own particular species of snail, just as almost every mammal has its own peculiar parasites.

An interesting corollary to the theory of isolation has been pointed out by Professor Cossar Ewart. Breeding within a narrow range often occurs in nature as the result of geographical or other barriers. In artificial conditions, this in-breeding often results in the development of what is called prepotency. This means that certain forms have an unusual power of transmitting their peculiarities, even when mated with dissimilar forms. In other words, certain variations have a strong power of hereditary persistence. There-fore, wherever through inbreeding (which implies isolation) prepotency has developed, there is no difficulty in understanding that even a small idiosyncrasy may come to stay. Reibmayr has developed the interesting thesis that in the evolution of a successful human stock there must be an alternation of long periods of inbreeding, in which characters are fixed and prepotency developed, and periods of outbreeding, in which fresh blood is introduced and the possibility of new departures secured.

General Retrospect.—Nature, Goethe said, is a book whose every page is full of import, and that is particularly true of the pages of the history of the animate world. Here the general trend of things has been progressive. How important if we can spell out the mechanism of progress! In this connection we venture to submit some general considerations.

A Common Error as to Fortuitousness.—Many have recoiled from a theory of evolution which seemed to rely so much on happy chances and on the occasionally apt ending of a chapter of accidents. What have we to say to this ?

It is in part a misunderstanding of words. When an evolutionist speaks of "fortuitous variations," he means that he is ignorant of their antecedent conditions. Fluctuating variations can be arranged so as to form a curve the curve of the frequency of error the curve which we get when we plot out measured results depending on a number of variable conditions. But the mere fact that we can make the curve shows a certain orderliness of distribution. Chance is a most orderly phenomenon. Furthermore, there is often marked definiteness in continuous variation, it accumulates generation after generation, one organ increases, another dwindles. Furthermore, it is by no means certain that any big step has been made by the accumulation of minute fluctuations; it is probable that discontinuous variations or mutations have counted for much, and they are no more accidental than sudden growth is. Furthermore, while there have been catastrophes in the course of nature, the only kind of elimination that counts in evolution is discriminate elimination, and what is discriminable cannot be fortuitous.

There seems to be nothing but misunderstanding in the allegation that the evolutionist interpretation relies on fortuitousness. If a cone falls from the fir tree under which we are sitting and kills a spider creeping on the ground, we say that it is quite fortuitous that cone and spider happen to come together at the same time in the same place. But progress in Nature does not depend on this sort of phenomenon. The elimination that counts is discriminate elimination.

But are not the variations that count fortuitous ? It is difficult to see much meaning in the term except that we are very ignorant of the antecedent conditions. Whether we believe that discontinuous mutations are of most moment, or that the fluctuations Darwin relied on are more important, whether we believe that variation is due to the stimulus of the variable body on the complex germ-plasm or to a germinal struggle of hereditary items, there is no good reason for calling them fortuitous. We must get away from the wooden way of thinking of variations as if they were so many coins which the organism took out of its pockets and staked in the game of life. Variations are always expressions of the creature's individuality, of its creative genius; they correspond to the poet's fancies and the philosopher's hypotheses; they represent organic imagination.

Preciousness of Individuality.—An evolutionary lesson which he who runs may read concerns the preciousness of individuality. Variations supply the raw material of progress, and variations spell individuality. This is one of the biological commonplaces which in human affairs we persistently ignore. In the educational mill whether of school or of college and in our inexorable social criticism, how systematically we pick off the buds of individuality idiosyncrasies and crankiness we say spoiling how many flowers. It is said that we do this to prevent failures and criminals, but are we very successful in this prevention ? How many of both do we make by repressing individuality ?

Importance of Struggle and Endeavour.—If there is one thing that the story of organic evolution teaches us more than another, it is the necessity of struggle or of endeavour. Everywhere she pronounces judgment on slackness, on the unlit lamp and the ungirt loin. Meredith writes of Nature's sifting:

" Behold the life of ease, it drifts,
The sharpened life commands its course;
She winnows, winnows roughly, sifts
To dip her chosen in her source.
Contention is the vital force
Whence pluck they brain, her prize of gifts."

More than Competitive Struggle.— At the same time, we libel nature's method if we picture it as comparable to that of a gladiatorial show with its uncompromising cry Voe victis; if we say that her only word is ruthless self-assertion, every one for himself and extinction take the hindmost; if we see only a thrusting aside and treading down of competitors.

Tennyson, who held such a clear mirror to Nature, writes:

"For Nature is one with rapine, a harm no preacher can heal,
The may-fly is tom by the swallow, the sparrow spear'd by the strike,
And the whole little wood where I sit is a world of plunder and prey."

But this is only one side of the picture.

It appears to us that the facts of mutual aid, of social life, of kin-sympathy and of parental care suffice to show that Huxley was in error in saying that "the cosmic process has no sort of relation to moral ends." This is so important that we must consider the matter more fully.

Ethical Aspect of Organic Evolution.—For untold ages the drama of organic evolution has been in progress, cast succeeding cast without any one having a real grasp of the plot. In comparatively recent times man, though busy on the stage, has become a calm spectator. Is it not significant of his critical spirit that he has come to doubt whether the great drama is a moral spectacle ?

Darwin painted a picture of nature which has impressed itself now on two generations of students. Every competent judge recognizes its strength and insight, but it is anti-Darwinian to call it finished or perfect. The most prominent features which it brought out were that flux of form which we call variation, the tendency of the river of life to overflow its banks, the ceaseless struggle for existence, the discriminate elimination which results, and the subtle interrelations and adaptations of the web of life. It is with the struggle for existence that we have now especially to deal.

Darwin pointed out that the phrase "struggle for existence" was to be taken in a wide and metaphorical sense, and he has a number of very interesting saving clauses. But the general perspective of his picture is clear, and leaves us with the impression of a sombre, more or less sanguinary, ceaseless struggle. We remember that the work of Malthus influenced Darwin (as it also influenced Wallace and Spencer); we may go further and recognize some truth in Geddes' thesis that science is a social phenomenon, and that the Darwinian conception was in part an unconscious projection on nature of the competitive conditions and competitive creed of the early industrial age. A reproduction of the picture has never the subtlety of the original, and the reproductions of the Darwinian picture are often rather hard and ugly prints. Nature is represented as a continuous Waterloo, as an endless gladiatorial show, as a dismal cockpit. And popularizers apart, leaders of thought like Huxley, have strengthened this impression, which is, to say the least, one-sided.

Attempt at a Correction of the Ultra-Darwinian Picture. Let us make a curve of the ascent of Vertebrates from water to dry land, and mark the position of the leading types according to the degree of their brain-development (which is generally a reliable index of structural progress). As the curve ascends, we find that the plummet of marital affection, the intensity of parental care, the expression of the gentler emotions, are all on the increase. The natural conditions in which each is said to be for himself, are evidently not antagonistic to the evolution of other-regarding behaviour.

The non-gregarious mammals are outnumbered by those that are social; the most secure, successful, and highly gifted birds are probably the rooks, the cranes, and the parrots also among the most gregarious; the monkeys most of which are a feeble folk are strong in their sociality. It is not then to self-assertiveness alone that Nature gives her sanction of survival.

When we take a survey of the course of organic nature we see hunger self-assertion competition a nutritive struggle of variable intensity. But organisms are also reproductive, they have species-regarding activities, altruistic impulses. The careful brooding mother-bird is de facto al-truistic. Hence, in part, a reproductive struggle, in which love may be stronger than hunger a reproductive factor in evolution which is not wholly concerned with self-gratification, but with self-sacrifice as well.

The important points are (1) that many of the big lifts in animal evolution, such as the origin of multicellular organisms or the origin of the mammalian type, imply the success of variations which cannot be regarded as of immediate individual advantage; (2) in the process of selection the premium on teeth and claws, or beaks and talons, is no greater than that on "the milk of animal kindness" and the warmth of the maternal heart; (3) the struggle for existence is often a quiet endeavour after well being. There is much gregariousness, there are many peaceful solutions of difficulty, there is frequent combination for defence and attack, there is a strong feeling of kin-ship, there is frequent cooperation and mutual aid. The world, Diderot says, is the abode of the strong; but it is also the home of the loving.'

Just as in the individual body we recognize the cooperation of organs as well as the struggle of parts, so in the great world of organisms we must recognize not only competition but cooperation, not only struggle but mutual aid, if we would draw any sane conclusion as to the ethical import of the great drama. As against Huxley's conclusion that the course of organic evolution through "a materialized logical process " has no ethical suggestion except that man must try to go on the opposite tack, it is interesting to place Geddes' conclusion that "Nature is a materialized ethical process," meaning by this mainly that some of the greatest steps in organic progress are interpretable as subordinations of the nutritive and self-regarding to the reproductive and species-regarding activities.

We must, of course, be careful not to pass from one anthropomorphism to another. We must be careful not to read the man into the beast, still less into the plant. Many animals exhibit self-sacrifice in the sense that they exert themselves often to their own detriment on behalf of their young, but this is not done out of a sense of duty any more than in the case of a human mother. In many cases, among insects, the mothers never see the young for which they labour. The mother mammal has no prevision of the welfare of the species, no control of her behaviour in reference to an ideal standard. Good she is, but not moral. None the less, there is objective self-sacrifice, and there is so much of it and of kindred phenomena that we must in accuracy correct the picture of Nature "all red in tooth and claw with ravine."

It is also evident that all the other-regarding activities pay, and are the subjects of selective direction. The selection-formula which applies to the swiftness of the fox and the correlate swiftness of the hare, applies also to the patient brooding of birds and the carefulness of the mammalian mother. Yet it seems absurd to deny that these mothers love their children, or to assert that physical motives saturate their behaviour. Is there not then some shifting of the theory's centre of gravity when we expressly allow that love pays ? The whole law and gospel of Nature is not to be summed up as "Upstairs on your neighbour's shoulders, living or dead, each for himself in the scrimmage and elimination take the hindmost." On a priori grounds it seems unlikely that struggle is the only word Nature has to say to man, or that what we recognize as one of the great laws of moral development self-realization in self- sacrifice should have no far-off counterpart in the rest of creation. We have hinted at a posteriori reasons for the belief that in this sense there are spiritual laws in the natural world, but what we have said must be followed up by reference to such contributions to the subject as Kropotkin's "Mutual Aid."

It may perhaps be objected that parasitism is a frequent phenomenon among animals, and has Nature's sanction of survival and success. The parasites are indeed legion; they attain conditions of "complete material well-being"; in spite of the enormous odds against them, involved in their usually intricate life-histories, full of hazardous vicissitudes, they hold their own. Fit for certain conditions, they survive, and survive uncommonly well. All this is true, but it is equally true that parasites are stamped with the stigmata of degeneracy.

The reason why we are so much concerned with getting away from an ultra-Darwinian picture of Nature is not merely because it seems to us inaccurate, but because the libellous conception projected from human society upon Nature has been brought back again to society as a guide and sanction of human conduct, even as an ethical and political ideal.

"The conception of the struggle for existence, it has been said, comes back to the explanation of human society with all the added force of its triumph in the solution of the greatest question with which natural science has hitherto successfully dealt."

Let be, they say, let nature alone, let them fight it out. Through struggle all progress has come, contention is the world's vital force, "the survival of the fittest," don't you know, in the struggle for existence. Let be, let be. The law of nature is every one for himself; there is a Hobbesian war of each against all; all creatures are Ishmaelites; and are not the results fair to see ?

Even if this were so, it is difficult to see why man, conscious of all, and in a sense above all, should fold his hands and say that Nature's method is good enough for him. As a matter of fact, Huxley's note-worthy thesis was that ethical progress for man depends upon his combating the cosmic process, pitting his microcosm against the macrocosm.

What we have been trying to show, however, is that Nature has more to say than "Every one for himself." There has been a selection of the other-regarding, of the self-sacrificing, of the gentle, of the loving.

If we wish to draw any ethical deduction from the course of organic evolution, we must have all the facts before us. We must not make idols of phrases, or rest content with partial pictures, or with projecting our social creed on Nature; we must go to Nature itself. When we do so, we find indeed that there is often competition to the death, much pain and suffering, very intense struggle for food and foothold. We may echo Darwin's sad words that the world is "too full of misery." We may say with Huxley that suffering, " this baleful product of evolution, increases in quantity and in intensity with advancing grades of animal organization until it attains its highest level in man." But this is not all. We see the success of self-sacrifice, the rewards of love, the stability of societies, and no end of joie de vivre. We find that the phrase struggle for existence has indeed to be used in a wide and metaphorical sense, that it is descriptive of the course of nature in which the multiplication of organisms and the natural limitations put to their desires for food, foothold, comfort and mates, bring about a state of affairs in which a premium is put on advantageous variations of whatever kind, and in which an elimination more rapid than natural death, or a lessening of the normal number and success of the family, handicaps those which are relatively unfit.

It seems important that we should try to make up our minds whether Huxley's picture of the course of animate nature is adequate. Must we not recognize that progress depends on much more than a squabble around the platter; that the struggle for existence is far more than an internecine struggle at the margin of subsistence, that it includes all the multitudinous efforts for self and others between the poles of love and hunger; that self-sacrifice and love are factors in evolution as well as self-assertion and death; that existence for many an animal means the well-being of a socially-bound or kin-bound creature in a social environment; that egoism is not satisfied until it becomes altruistic ?

Emotional Value of the Evolutionary Picture.

Finally, as to the esthetic value of the evolutionary picture, let us recall Darwin's well-known words: "To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of an individual. When I view all beings, not as special creations, but as lineal descendants of some few beings who lived before the first bed of the Silurian was deposited, they seem to me to become ennobled."

"There is a grandeur in this view of life, with its several powers having been originally breathed 6y the Creator into a few forms or into one, and that while this planet has gone cycling on, according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved."