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as something which is beyond modification, unchanging so long as it exists.

"I believe," said the rose to the lily in the parable, “that our gardener is immortal. I have watched him from day to day since I bloomed, and I see no change in him. The tulip who died yesterday told me the same thing."

As a flash of lightning in the duration of the night, so is the life of man in the duration of nature. When one looks out on a storm at night he sees for an instant the landscape illumined by the lightning flash. All seems at rest. The branches in the wind, the flying clouds, the falling rain, are all motionless in this instantaneous view. The record on the retina takes no account of change, and to the eye the change does not exist. Brief as the lightning flash in the storm is the life of man compared with the great time record of life upon earth. To the untrained man who has not learned to read these records, species and types in life are enduring. From this illusion arose the theory of special creation and permanence of type, a theory which could not persist when the facts of change and the forces causing it came to be studied in detail.

But when men came to investigate the facts of individual variation and to think of their significance, the current of life no longer seemed at rest. Like the flow of a mighty river, ever sweeping steadily on, never returning, is the movement of all life. The changes in human history are only typical of the changes that take place in all living creatures. In fact, human history is only a part of one great life current, the movement of which is everywhere governed by the same laws, depends on the same forces, and brings about like results..

Organic evolution, or bionomics, is one of the most comprehensive of all the sciences, including in its subject matter not only all natural history, not only processes like cell division and nutrition, not only the laws of heredity, variation, segregation, natural selection, and mutual help, but all matters of human history, and the most complicated relations of civics, economics, and ethics. In this enormous science no fact can be without a meaning, and no fact or its underlying forces can be separated from the great forces whose interaction from moment to moment writes the great story of life.

And as the basis to the science of bionomics, as to all other science, must be taken the conception that nothing is due to

chance or whim. Whatever occurs comes as the resultant of moving forces. Could we know and estimate these forces, we should have, so far as our estimate is accurate and our logic perfect, the gift of prophecy. Knowing the law, and knowing the facts, we should foretell the results. To be able in some degree to do this is the art of life. It is the ultimate end of science, which finds its final purpose in human conduct. “A law,” according to Darwin, “is the ascertained sequence of events.” The actual sequence of events it is, in fact, but man knows nothing of what is necessary, only of what has been ascertained to occur. Because human observation and logic can be only partial no law of life can be fully stated. Because the processes of human mind are human, with organic limitations, the study of the mind itself becomes a part of the science of bionomics. For it is itself an instrument or a combination of instruments by which we acquire such knowledge of the world outside of ourselves as may be needed in the art of living, in the degree in which we are able to practice that art. The necessary sequence of events exists, whether we are able to comprehend it or not. The fall of a leaf follows fixed laws as surely as the motion of a planet. It falls by chance because its short movement gives us no time for observation and calculation. It falls by chance because, its results being unimportant to us, we give no heed to the details of its motion. But as the hairs of our head are all numbered, so are numbered all the gyrations and undulations of every chance autumn leaf. All processes in the universe are alike natural. The creation of man or the growth of a state is as natural as the formation of an apple or the growth of a snowbank. All are alike supernatural, for they all rest on the huge unseen solidity of the universe, the imperishability of matter, the conservation of energy, and the immanence of law. We sometimes classify sciences as exact and inexact, in accordance with our ability exactly to weigh forces and results. The exact sciences deal with simple data accessible and capable of measurement. The results of their interactions can be reduced to mathematics. Because of their essential simplicity, the mathematical sciences have been carried to great comparative perfection. It is easier to weigh an invisible planet than to measure the force of heredity in a grain of corn. The sciences of life are inexact because the human mind can never grasp all their data. The combined effort of all men, the flower of the altruism of the ages, which we call science, has made only a beginning in such study. But, however incomplete our realization of the laws of life, we may be sure that they are never broken. Each law is the expression of the best possible way in which causes and results can be linked. It is the necessary sequence of events, therefore the best sequence, if we may imagine for a moment that the human words “good" and “bad” are applicable to world processes. The laws of nature are not executors of human justice. Each has its own operation and no other. Each represents its own tendency toward cosmic order. A law in this sense cannot be “broken.” “If God should wink at a single act of injustice,” says the Arab proverb, “the whole universe would shrivel up like a cast-off snake skin.” The laws of nature have in themselves no necessary principle of progress. Their functions, each and all, may be defined as cosmic order. The law of gravitation brings order in rest or motion. The laws of chemical affinity bring about molecular stability. Heredity repeats strength or weakness, good or ill. with like indifference. The past will not let go of us; we cannot let go of the past. The law of mutual help brings the perpetuation of weakness as well as the strength of coöperation. Even the law of pity is pitiless, and the law of mercy merciless. The nerves carry sensations of pleasure or pain, themselves as indifferent as the telegraph wire, which is man's invention to serve similar purposes. Some men who call themselves pessimists because they cannot read good into the operations of nature forget that they cannot read evil. In morals the law of competition no more justifies personal, official, or national selfishness or brutality than the law of gravitation justifies the shooting of a bird. The science of bionomics centers about the theory of descent, the belief that organs and species as we know them are derived from other and often simpler forms by processes of divergence and adaptation. According to this theory all forms of life now existing, or that have existed on the earth, have risen from other forms of life which have previously lived in turn. All characters and attributes of species and groups have developed with changing conditions of life. The homologies among animals are the results of connon descent. The differences

are due to various influences, one of the leading forces among these being competition in the struggle for existence between individuals and between species, whereby those best adapted to their surroundings live and reproduce their kind.

This theory is now the central axis of all biological investigation in all its branches, from ethics to histology, from anthropology to bacteriology. In the light of this theory every peculiarity of structure, every character or quality of individual or species, has a meaning and a cause. It is the work of the investigator to find this meaning as well as to record the fact. “One of the noblest lessons left to the world by Darwin,” says Frank Cramer, “is this, which to him amounted to a profound, almost religious conviction, that every fact in nature, no matter how insignificant, every stripe of color, every tint of flowers, the length of an orchid's nectary, unusual height in a plant, all the infinite variety of apparently insignificant things, is full of significance. For him it was an historical record, the revelation of a cause, the lurking place of a principle.” It is therefore a fundamental principle of the science of bionomics that every structure and every function of to-day finds its meaning in some condition or in some event of the past.

CHAPTER II

VARIETY AND UNITY IN LIFE

L'espèce, c'est un être qui dans ses générations successives présente toujours les mêmes caractères d'organisation; il faut ajouter dans les mêmes localités, et les mêmes circonstances extérieures.”— RAMBUR, 1842.

“That mystery of mysteries as it has been called by one of our greatest philosophers ”—this is Darwin's phrase regarding

the problem before us, the origin of species-the origin or cause of variety in the life of the globe.

That variety exists, that there are many kinds and types, grades and grada tions in animal and vegetable life is evident to all. Birds and trees, beetles and butterflies, fishes and flowers, ferns and blades of grass, all these are objects of constant recognition. The green cloak which covers the brown earth is the shield under which myriads of organisms, brown and green, carry on their life work, and still

farther below the level of l'ig. 1.-Long-horned boring beetle from our Ordinary

our ordinary notice exists

OLI Central America (one-half natural size). a range of life scarcely less

1 This figure and the others in this chapter are introduced simply to illustrate graphically the variety of animal form.

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