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MAGNALIA NATURE: OR THE GREATER PROBLEMS OF

BIOLOGY.1

By D'ARCY WENTWORTH THOMPSON, C. B.,

Professor of Natural History in University College, Dundee (University of St. Andrews).

The science of zoology, all the more the incorporate science of biology, is no simple affair, and from its earliest beginnings it has been a great and complex and many-sided thing. We can scarce get a broader view of it than from Aristotle, for no man has ever looked upon our science with a more farseeing and comprehending eye. Aristotle was all things that we mean by "naturalist" or "biologist." He was a student of the ways and doings of beast and bird and creeping thing; he was morphologist and embryologist; he had the keenest insight into physiological problems, though his age lacked that knowledge of the physical sciences without which physfology can go but a little way; he was the first and is the greatest of psychologists; and in the light of his genius biology merged in a great philosophy.

I do not for a moment suppose that the vast multitude of facts which Aristotle records were all, or even mostly, the fruit of his own immediate and independent observation. Before him were the Hippocratic and other schools of physicians and anatomists. Before him there were nameless and forgotten Fabres, Roesels, Réaumurs, and Hubers, who observed the habits, the diet, and the habitations of the sand wasp or the mason bee; who traced out the little lives and discerned the vocal organs of grasshopper and cicada; and who, together with generations of bee-keeping peasants, gathered up the lore and wisdom of the bee. There were fishermen skilled in all the cunning of their craft, who discussed the wanderings of tunny and mackerel, swordfish or anchovy; who argued over the ages, the breeding places, and the food of this fish or that; who knew how the smooth dogfish breeds, two thousand years before Johannes Müller; who saw how the male pipefish carries its young, before Cavolini; and who had found the nest of the nest-building rockfishes before

1 Presidential address delivered to the zoological section of the British Association Aug. 31, 1911. Reprinted by permission from author's printed copy.

Gerbe rediscovered it almost in our own day. There were curious students of the cuttle fish (I sometimes imagine they may have been priests of that sea-born goddess to whom the creatures were sacred), who had diagnosed the species, recorded the habits, and dissected the anatomy of the group, even to the discovery of that strange hectocotylus arm that baffled Della Chiaje, Cuvier, and Koelliker, and that Vérany and Heinrich Müller reexplained.

All this varied learning Aristotle gathered up and wove into his great web. But every here and there, in words that are unmistakably the master's own, we hear him speak of what are still the great problems and even the hidden mysteries of our science; of such things as the nature of variation, of the struggle for existence, of specific and generic differentiation of form, of the origin of the tissues, the problems of heredity, the mystery of sex, of the phenomena of reproduction and growth, the characteristics of habit, instinct, and intelligence, and of the very meaning of life itself. Amid all the maze of concrete facts that century after century keeps adding to our store, these, and such as these, remain the great mysteries of natural science—the magnalia naturæ, to borrow a great word from Bacon, who in his turn had borrowed it from St. Paul.

Not that these are the only great problems for the biologist, nor that there is but a single class of great problems in biology, for Bacon himself speaks of the magnalia naturæ, quoad usus humanos, the study of which has for its objects "the prolongation of life or the retardation of age, the curing of diseases counted incurable, the mitigation of pain, the making of new species and transplanting of one species into another," and so on through many more. Assuredly, I have no need to remind you that a great feature of this generation of ours has been the way in which biology has been justified of her children in the work of those who have studied the magnalia naturæ, quoad usus humanos.

But so far are biologists from being nowadays engrossed in practical questions, in applied and technical zoology, to the neglect of its more recondite problems, that there never was a time when men thought more deeply or labored with greater zeal over the fundamental phenomena of living things; never a time when they reflected in a broader spirit over such questions as purposive adaptation, the harmonious working of the fabric of the body in relation to environment, and the interplay of all the creatures that people the earth; over the problems of heredity and variation; over the mysteries of sex and the phenomena of generation and reproduction, by which phenomena, as the wise woman told, or reminded, Socrates, and as Harvey said again (and for that matter, as Coleridge said, and Weismann, but not quite so well)—by which, as the wise old woman said, we gain our glimpse of insight into eternity and immortality. These, then, together with

the problem of the origin of species, are indeed magnalia naturæ; and I take it that inquiry into these, deep and wide research specially directed to the solution of these, is characteristic of the spirit of our time and is the password of the younger generation of biologists.

Interwoven with this high aim which is manifested in the biological work of recent years is another tendency. It is the desire to bring to bear upon our science, in greater measure than before, the methods and results of the other sciences, both those that in the hierarchy of knowledge are set above and below and those that rank alongside of our own.

Before the great problems of which I have spoken the cleft between zoology and botany fades away, for the same problems are common to the twin sciences. When the zoologist becomes a student not of the dead but of the living, of the vital processes of the cell rather than of the dry bones of the body, he becomes once more a physiologist, and the gulf between these two disciplines disappears. When he becomes a physiologist, he becomes, ipso facto, a student of chemistry and of physics. Even mathematics has been pressed into the service of the biologist, and the calculus of probabilities is not the only branch of mathematics to which he may usefully appeal.

The physiologist has long had as his distinguishing characteristic, giving his craft a rank superior to the sister branch of morphology, the fact that in his great field of work and in all the routine of his experimental research, the methods of the physicist and the chemist, the lessons of the anatomist, and the experience of the physician, are inextricably blended in one common central field of investigation and thought. But it is much more recently that the morphologist and embryologist have made use of the method of experiment and of the aid of the physical and chemical sciences-even of the teachings of philosophy-all in order to probe into properties of the living organism that men were wont to take for granted or to regard as beyond their reach under a narrower interpretation of the business of the biologist. Driesch and Loeb and Roux are three among many men who have become eminent in this way in recent years, and their work we may take as typical of methods and aims such as those of which I speak. Driesch, both by careful experiment and by philosophic insight; Loeb, by his conception of the dynamics of the cell and by his marvelous demonstrations of chemical and mechanical fertilization; Roux, with his theory of autodetermination and by the labors of the school of Entwickelungsmechanik which he has founded, have all in various ways, and from more or less different points of view, helped to reconstruct and readjust our ideas of the relations of embryological processes, and hence of the phenomenon of life itself, on the one hand, to physical causes (whether external to or latent in the mecha

nism of the cell), or, on the other, to the ancient conception of a vital element, alien to the province of the physicist.

No small number of theories or hypotheses, that seemed for a time to have been established on ground as firm as that on which we tread, have been reopened in our day. The adequacy of natural selection to explain the whole of organic evolution has been assailed on many sides; the old fundamental subject of embryological debate between the evolutionists or preformationists (of the school of Malpighi, Haller, and Bonnet) and the advocates of epigenesis (the followers of Aristotle, of Harvey, of Caspar Fr. Wolff, and of Von Baer) is now discussed again, in altered language, but as a pressing question of the hour; the very foundations of the cell theory have been scrutinized, to decide, for instance, whether the segmented ovum, or even the complete organism, be a colony of quasi independent cells or a living unit in which cell differentiation is little more than a superficial phenomenon; the whole meaning, bearing, and philosophy of evolution has been discussed by Bergson, on a plane to which neither Darwin nor Spencer ever attained; and the hypothesis of a vital principle, or vital element, that had lain in the background for near a hundred years, has come into men's mouths as a very real and urgent question, the greatest question for the biologist of all.

In all ages the mystery of organic form, the mystery of growth and reproduction, the mystery of thought and consciousness, the whole mystery of the complex phenomena of life, have seemed to the vast majority of men to call for description and explanation in terms alien to the language which we apply to inanimate things; though at all times there have been a few who sought, with the materialism of Democritus, Lucretius, or Giordano Bruno, to attribute most, or even all, of these phenomena to the category of physical causation.

For the first scientific exposition of vitalism we must go back to Aristotle, and to his doctrine of the three parts of the tripartite soul; according to which doctrine, in Milton's language, created things "by gradual change sublimed, to vital spirits aspire, to animal, to intellectual." The first and lowest of these three, the fʊxǹi OpeлTIKÝ, by whose agency nutrition is effected, is ǹ лρúτη fʊxý, the inseparable concomitant of life itself. It is inherent in the plant as well as in the animal, and in the Linnæan aphorism, vegetabilia crescunt et vivunt, its existence is admitted in a word. Under other aspects it is all but identical with the ψυχή αυξητική and γεννητική, the soul of growth and of reproduction; and in this composite sense it is no other than Driesch's "Entelechy," the hypothetic natural agency that presides over the form and formation of the body. Just as Driesch's psychoid or psychoids, which are the basis of instinctive phenomena, of sensation, instinct, thought, reason, and all that directs that body

which entelechy has formed, are no other than the aloŋteký, whereby animalia vivunt et sentiunt, and the deavontekh, to which Aristotle ascribes the reasoning faculty of man. Save only that Driesch, like Darwin, would deny the restriction of vous, or reasoning, to man alone, and would extend it to animals, it is clear, and Driesch himself admits,1 that he accepts both the vitalism and the analysis of vitalism laid down by Aristotle.

The лευμа of Galen, the vis plastica, the vis vitæ formatrix, of the older physiologists, the Bildungstrieb of Blumenbach, the Lebenskraft of Paracelsus, Stahl, and Treviranus, "shaping the physical forces of the body to its own ends,' ""dreaming dimly in the grain of the promise of the full corn in the ear" (to borrow the rendering of an Oxford scholar), these and many more, like Driesch's "Entelechy" of to-day, are all conceptions under which successive generations strive to depict the something that separates the earthy from the living, the living from the dead. And John Hunter described his conception of it in words not very different from Driesch's, when he said that his principle, or agent, was independent of organization, which yet it animates, sustains, and repairs; it was the same as Johannes Müller's conception of an innate "unconscious idea."

Even in the Middle Ages, long before Descartes, we can trace, if we interpret the language and the spirit of the time, an antithesis that, if not identical, is at least parallel to our alternative between vitalistic and mechanical hypotheses. For instance, Father Harper tells us that Suarez maintained that in generation and development a divine interference is postulated, by reason of the perfection of living beings; in opposition to St. Thomas, who (while invariably making an exception in the case of the human soul) urged that, since the existence of bodily and natural forms consists solely in their union with matter, the ordinary agencies which operate on matter sufficiently account for them.3

But in the history of modern science, or of modern physiology, it is, of course, to Descartes that we trace the origin of our mechanical hypotheses-to Descartes, who, imitating Archimedes, said: "Give me matter and motion and I will construct the universe." In fact, leaving the more shadowy past alone, we may say that it is since Descartes watched the fountains in the garden and saw the likeness

1 Science and Philosophy of the Organism (Gifford Lectures), ii. p. 83, 1908.

2 Cit. Jenkinson (Art. “Vitalism" in Hibbert Journal, April, 1911), who has given me the following quota. tion: "Das Weitzenkorn hat allerdings Bewusstsein dessen was in ihm ist und aus ihm werden kann, und traümt wirklich davon. Sein Bewusstsein und seine Traume mögen dunkel genug sein"; Treviranus, Erscheinungen und Gesetze des organischen Lebens, 1831.

3 "Cum formarum naturalium et corporalium esse non consistat nisi in unione ad materiam, ejusdam agentis esse videtur eas producere, cujus est materiam transmutare. Secundo, quia cum hujusmodi formæ non excedant virtutem et ordinem et facultatem principiorum agentium in natura, nulla videtur necessitas eorum originem in principia reducere altiora." Aquinas, De Pot. Q., iii. a 11. Cf. Harper, Metaphysics of the School. iii. 1. p. 152.

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