(The essays contained in this volume were written on diffe...)
The essays contained in this volume were written on different occasions mostly in response to requests for a popular presentation of the results of the author's investigations.
Jacques Loeb was a German-born American biologist, physiologist, and author. Loeb is remembered for his work on the physiology of the brain, animal tropisms (involuntary orientations), regeneration of tissue, and the duration of life. He is also noted for his arguments in favour of mechanism, the belief that the phenomena of life can be explained in terms of physical and chemical laws.
Background
Jacques Loeb was born on April 7, 1859 in Mayen, Rhine Province, Kingdom of Prussia (now Rhineland-Palatinate, Germany). He was the son of Benedict and Barbara (Isay) Loeb. They were a Jewish family from the German Eifel region. His parents died when he was young.
Education
Jacques Loeb attended the Askanisches Gymnasium in Berlin. He then studied philosophy at the University of Berlin (now Humboldt University of Berlin) and University of Strasbourg, receiving a medical degree in 1884 and passing the Staatsexamen in 1885.
In 1886 Loeb went to Würzburg as an assistant to Adolf Fick. Two years later he became an assistant to Friedrick Goltz in Strasburg. The winters of 1889-1890 and 1890-1891 he spent at Naples, carrying on experiments in heteromorphosis. In 1891 he accepted a position at Bryn Mawr and a year later went to the University of Chicago. He remained there until 1902 when he accepted a call to the University of California. In 1910 he became a member of the Rockefeller Institute for Medical Research and remained there until his death.
Loeb's original bent was toward philosophy but he was not satisfied with metaphysics: rather he demanded that the great questions of philosophy be put to experimental test.
One of the most fundamental of these questions which had a special fascination for him was the freedom of the will. Could this be tested experimentally? In the universities of Berlin and Munich, and in the laboratory of Goltz at Strassburg, he found no answer though Goltz was then experimenting on the brains of dogs by a method which at first seemed promising. At last from Julius von Sachs, the famous botanist of Würzburg, he obtained a clue. Sachs controlled the behavior of plants with great precision on the assumption that plants are simple machines.
Loeb tried similar experiments on animals and found that in many cases they reacted with the same machinelike regularity as plants. He called such reactions tropisms. Before the age of thirty he published the "tropism theory" which was destined to make him famous. An illustration of his method of thought is apparent in the study of the behavior of certain caterpillars that emerge from the ground in spring and climb up trees to the tips of the branches where the opening buds furnish food. What leads them to do this, in some cases before the buds have started to open? The current answer was: A marvelous instinct that directs them to their food without any apparent cause and which is inherited from generation to generation.
Not satisfied with this explanation, Loeb made the following experiment. He placed some of the caterpillars in a test-tube in a darkened room and directed the closed end toward the light. The caterpillars crawled to this end and there remained. Food was then pushed along the tube until it almost touched them but, as Loeb expressed it, they were slaves to the light, just as plants are; they could not turn around to take the food which was beside them and they starved to death within easy reach of it. The reason for their climbing trees was now clear: they were attracted by the light and the only assumption needed in regard to heredity was that they inherited some substance which made them sensitive to the light. To this extent, they were mechanisms, completely under the control of the experimenter. Thus at the outset of his career, Loeb concluded that certain instincts may be resolved into tropisms. He subsequently developed these ideas.
Eventually, he was able, by adding carbonic acid to water, to produce in an aquatic animal, ordinarily indifferent to the light, a reaction drawing it irresistibly toward a source of illumination. This led him to question whether certain psychological problems might be placed upon a physicochemical basis. If behavior might be changed by the addition of an acid why not by the secretions of a gland? "Might not this idea be applied to attraction between the sexes, which may involve a change from a selfish to an altruistic attitude? And why limit the consideration to glandular products? Since Pawlow, the Russian physiologist, and his pupils have produced a salivary secretion in dogs by means of optical or auditory signals it no longer appears strange that what we call an idea should bring about chemical changes in the body".
Loeb believed that a fixed idea may produce a sort of tropism to which the mind mechanically responds without any such process as deliberate choice and this may happen over and over again until a deliberate choice is almost or quite impossible. He even believed that much which appears to be a deliberate choice is really largely mechanical and that in ordinary human actions there is far less freedom of the will than would appear at first sight. When he first announced his ideas in the nineties they created a sensation. They came at a time when the trend toward anthropomorphic thinking was very strong and they had a marked influence upon philosophy, psychology, sociology, and kindred disciplines. But Loeb was not content merely to influence the will of the animal; he wished also to control the entire process of life, the whole course of development from beginning to end, and his experiments in these directions led to some brilliant discoveries.
Development usually commences with the fertilization of the egg. This was regarded as the most mysterious of life processes. The way in which Loeb set to work to solve the mystery is characteristic. He reasoned that the sperm carries into the egg something which starts its development. In an effort to discover whether he could introduce this substance without using sperm, he subjected the egg to treatment of the most varied sort and discovered a number of methods, both chemical and physical, of starting development without the aid of sperm. He found that in some cases these parthenogenetic animals, as they are called, could be raised to full and normal maturity. He also found means of bringing about fertilization between different species and of thus producing hybrids not occurring in nature.
From this beginning, he found means of controlling generation in such a way as to produce at will all sorts of things not ordinarily found in nature, such as Siamese twins and triplets, and two-headed animals. He believed that in this way he could lay the foundation for a theory of development. From this standpoint, he studied regeneration, a field that attracted him because it was so long a stronghold of mysticism. It had often been assumed that when a missing part of the organism is replaced, there must be a "directive force" which ensures that the regenerated part shall be exactly what is needed to complete the organism. Loeb found that this is not always so; under some conditions a hydroid instead of regenerating a lost stolon produces a polyp "so that we have an animal terminating at both ends of its body in a head". Such cases are difficult to explain on the basis of a "directive force" which operates to supply the needs of the animal; they are less difficult to explain if it is assumed that the formation of organs is due to the accumulation of specific substances (as had been postulated in the case of plants) at the place where the organ in question is to be formed. Such an accumulation of substances can be controlled to a certain extent by the experimenter.
Loeb went on to examine from a mechanistic approach the equally important question of adaptation. He found that many characteristics of the organism which are regarded as adaptive may be explained on a mechanistic basis. The reactions of animals to light depend on a photochemical substance that may arise without reference to adaptation. It is not necessary to suppose that heliotropism can arise only in response to a need or under the guidance of a "directive force. " Loeb emphasized the fact that in many cases what are called "adaptations" arose without any "directive force" before they could possibly have been useful. Where adaptations really exist they can often be explained on a physico-chemical basis so that the assumption of a directive force is not necessary.
The process of death, which in higher animals terminates development after a longer or shorter interval, had a great fascination for Loeb. He made experiments that showed that in certain animals death could be postponed by keeping the temperature sufficiently low. He also called attention to the fact that by means of his method of artificial parthenogenesis the life of the egg can be indefinitely prolonged. His brother Leo Loeb, by means of transplantation and tissue culture, had succeeded in doing the same thing for the ordinary cells of the body. Back of his desire to control life processes was his profound belief that the ills of mankind are largely due to ignorance and superstition and that if some of the mysteries of biology could be cleared up the greatest possible good to mankind would result.
The great driving force of his life lay not only in a powerful intellectual urge but also in profound emotion. He spared no effort in his attempt to reduce life processes to mechanism. It may be added that he was often rewarded with startling success. He made extensive use of the dissociation theory of Arrhenius which led him to discover artificial parthenogenesis and the action of balanced solutions, that is, solutions like blood and sea water, in which a salt, which is toxic by itself, serves as an antidote to other toxic salts so that when mixed in proper proportions a non-toxic mixture is obtained. He also found in the principle of the Donnan equilibrium a clue to unraveling certain puzzling features in the behavior of colloids, the study of which is so important for biology. He was actively engaged in this work when, during a visit to Bermuda, he was overtaken by death.
Aside from his numerous papers, Loeb also published the following books: Der Heliotropismus der Tiere und seine Übereinstimmung mit dem Heliotropismus der Pflanzen (1890); Untersuchungen zur physiologischen Morphologie der Tiere, Volume I, Über Heteromorphose, Volume II, "Organbildung und Wachstum" (1891 - 92); Comparative Physiology of the Brain and Comparative Psychology (1900); Studies in General Physiology (1905), containing reprints of several papers previously published; The Dynamics of Living Matter (1906); Untersuchungen über künstliche Parthenogenese und das Wesen des Befruchtungsvorgangs (1906); The Mechanistic Conception of Life (1912); Artificial Parthenogenesis and Fertilization (1913); The Organism as a Whole (1916); Forced Movements, Tropisms, and Animal Conduct (1918); Proteins and the Theory of Colloidal Behavior (1922); and Regeneration (1924). He also founded and edited, in collaboration with W. J. V. Osterhout, the Journal of General Physiology, and in collaboration with Osterhout and T. H. Morgan, edited the Monographs on Experimental Biology.
Loeb believed that the development of scientific knowledge could lead to a philosophy free from mysticism by which the human being could achieve a lasting harmony with itself and its environment. Such a goal he believed could be reached only by research, which would eventually reveal altruism as an innate property of human nature, just as the tropisms and instincts are inherent in lower organisms.
In making his experiments Loeb believed that the only satisfactory method was to follow the procedure of the exact sciences and to try to express all the observed phenomena by equations containing no arbitrary constants. He followed the progress of physics and chemistry with the closest attention and seized upon all that could be made useful in solving his own problems.
Quotations:
"If our existence is based on the play of blind forces and only a matter of chance; if we ourselves are only chemical mechanisms - how can there be an ethics for us? The answer is, that our instincts are the root of our ethics and that the instincts are just as hereditary as is the form of our body. We eat, drink, and reproduce not because mankind has reached an agreement that this is desirable, but because, machine-like, we are compelled to do so. We are active, because we are compelled to be so by processes in our central nervous system; and as long as human beings are not economic slaves the instinct of successful work or of workmanship determines the direction of their action. The mother loves and cares for her children, not because metaphysicians had the idea that this was desirable, but because the instinct of taking care of the young is inherited just as distinctly as the morphological characters of the female body. We seek and enjoy the fellowship of human beings because hereditary conditions compel us to do so. We struggle for justice and truth since we are instinctively compelled to see our fellow beings happy. Economic, social, and political conditions, or ignorance and superstition, may warp and inhibit the inherited instincts and thus create a civilization with a faulty or low development of ethics. Individual mutants may arise in which one or the other desirable instinct is lost, just as individual mutants without pigment may arise in animals; and the offspring of such mutants may, if numerous enough, lower the ethical status of a community. Not only is the mechanistic conception of life compatible with ethics: it seems the only conception of life which can lead to an understanding of the source of ethics."
"What progress humanity has made, not only in physical welfare but also in the conquest of superstition and hatred, and in the formation of a correct view of life, it owes directly or indirectly to mechanistic science."
Personality
Loeb was above all an idealist. Protected by academic life, and by a devoted wife, he lived largely in a world of ideals which dominated his life. He embodied Pasteur's profession of faith before the Academy, in the words now graven on his tomb: "Heureux celui qui porte en soi un dieu, un idéal de beauté, et qui lui obéit." He possessed the austerity which goes naturally with high ideals, and the temper of the aristocrat, but he had also a tender heart which responded to the sorrows of all who suffered and a sympathy for the masses who struggled against oppression, whether economic or spiritual.
His temperament was that of an artist, running the gamut of the creative imagination, its brooding depression, its rare exaltation. He could not remain on the level of mediocrity. The outstanding feature of his intellectual equipment was his creative faculty. But fortunately his imagination was associated with a keen critical sense. The more audacious the conception, the more rigorously he tested it: he repeated his experiments over and over again. Few of his observations of fact had subsequently to be modified. He published only a small part of his experimental work, and few of his many ideas found their way into print. He would often think aloud in the course of a lecture, making and discarding one hypothesis after another. Ideas came to him so rapidly that often he did not know which to follow, but when he had singled one out he was not satisfied until he had thoroughly tested it. To him research was a happy adventure, however much it involved what might be called drudgery. He selected problems on the basis of their importance, and his mind gloried in difficult problems. It was always alert, poised to turn easily in any direction.
He had supreme confidence in the cause to which he consecrated his life: a conviction that mechanism could explain the most baffling mysteries. It almost approached a dogma. It was a militant faith which grew firmer with each new discovery, and if a philosophy be judged by its fruits, his convictions justified themselves. The emotional character of his thought, in conversation, was sometimes bewildering to more phlegmatic natures. A visitor to his laboratory was quite likely to leave in a somewhat breathless state. The rapidity with which he evolved, examined, and rejected ideas was astonishing. But the conceptions that survived were thought through and worked over under an emotional stress which is often evident in his writing. This emotional urge seemed to be capable of lifting him above personal considerations to levels of complete objectivity. And this seemed to him the true scientific attitude.
Interests
philosophy of free will
Connections
Loeb married Anne L. Leonard, a scientist, in October 1890. They had three children.