Donald Fleming's new edition of Loeb's Mechanistic Conception of Life explains both the former stellar position and the present eclipse of the biologist Jacques Loeb (1859-1924). When the first edition of this book appeared in 1912, Loeb ranged in poplar opinion with Galileo, Newton, and Darwin: he was a great-scientific innovator, who applied the principles of his science to the problems of ordinary men. This second edition of Loeb's most famous book-recalls an alternative to today's canon that the principles of scientific inquiry may be legitimately applied only to the defined problems of science.

Loeb believed in determinism, mechanism, and materialism as The Truth, not as working hypotheses useful for getting good results in limited experimental situations. He was a philosophical monist: he believed one principle, determinism, governed the whole universe. He felt he could therefore, apply his experimental results to political justice, social welfare, and ethics. Mechanistic science was the source of whatever progress men had made, he said, "not only in physical welfare but also in the conquest of superstition and hatred, and in the formation of a correct view of life." The possible social and philosophical applications were Loeb's motivation to experimental.

Loeb first attracted public attention by showing that tropisms govern some kinds of animal behavior as strictly as they had been shown to govern plant behavior by his teachers. (A tropism is an automatic, mechanical orientation of an organism in response to some controlling factor in its environment. A moth which can fly only toward a light and a plant which can grow only in the direction of light both show positive phototropisms.)

By simple chemical alterations of the water in which marine organisms lived, Loeb caused tropisms in animals which, under normal circumstances, appeared to be acting "spontaneously." He concluded that all animal behavior was tropistic, or would be if we only knew the controlling physico-chemical forces.

Novum Ovum

Having "proved" behavior deterministic, Loeb moved on to fertilization, for he found that vitalists (who opposed mechanists) were always using the mystery of the process of fertilization to slip a soul into animals. In 1899, by chemical alterations in water containing sea urchin eggs, he was able to fertilize the eggs and cause them to develop into larvae without any male sperm at all. For this work he gained world renown. Professor Fleming's introduction recounts that maiden ladies stopped bathing at the sea shore for fear of what the water might do to them; barren couples earnestly entreated Loeb to provide them with children.

In The Mechanistic Conception of Life, Loeb describes his experiments on tropisms and fertilization with great clarity. Loeb wanted readers to understand his experiments--they were his tools to convince people of the correctness of his metaphysics.

This jacketing of concrete experiments in metaphysical clothes, Professor Fleming points out, makes Loeb seem scientifically old-fashioned. The experimental procedures Loeb originated are now routine in biology, and many of his experimental results still stand, though viewed with a different emphasis; but Loeb's use of experimentals to divine general Truth has a fin-de-siecl air, and most scientists view similar attempts today with embarrassment.

His life-long attempts were embarrassing to Loeb, too, when World War I broke out, for masses of men seemed to be mechanically controlled forced as if by tropisms to march into battle. Here was mechanism leading men into massacre and mayhem.

By the end of the war, Loeb was not the same scientist; though he reached his greatest acclaim then as a scientific commentator on the issues of ethics and welfare important to everyman, he himself turned to his laboratory because it allowed him to forget the world outside.

In Europe, Vaihinger's philosophy of "as-if"--one should act on the basis of scientific generalizations "as if" they were True--and in America variants of the pragmatism of William James pervaded the credos of most scientists.

A Metaphysical Spasm

What happened to loeb in biology happened, I think, almost across the board in science around the same time. Just as the belief that biology gives the Truth about Life eroded, so did the belief that physics gives the Truth about the real, as opposed to the apparent, physical world.

Einstein shared Loeb's conviction that scientific truths illuminate some real world, and were not merely postulates of convenience. Yet Einstein's own work, like Loeb's contributed to the overthrow of that position. In 1927, the physicist Percy Bridgman questioned how it was possible that Newtonian theory, which had been accepted throughout the nineteenth century, could be overthrown. He answered, in brief, that Einstein had replaced Newton's absolute concepts--absolute space, absolute motion, absolute time--with concepts defined in terms of particular observers, such as time and length relative to an observer. The truth arrived at by these observers were necessarily more limited in scope, more subject to amendment by new experience.

Mathematics had been partially unshackled from the physical world by the discovery of non-Euclidean geometrics in the nineteenth century, but the publication of Principia Mathematica in 1908 burst the chains. This three-volume monument by Bertrand Russell and Alfred North Whitehead expressed the fundamental concepts of mathematics in terms of still simpler concepts of logic, and showed that mathematics may be viewed as a game of manipulating symbols according to rules. Since mathematicians can adopt any rules they want, the truths proved in mathematics can have no necessary connection with the world outside of mathematics.

Biology, physics, and mathematics were not the only sciences whose metaphysical applicability contracted drastically at the beginning of this century. With the contraction came a greater freedom to use scientific techniques to make more science for its own sake. This advantage, however, increased the distance between the daily concerns of everyman and the technical results of science. The few scientists who try today to link the two are rarely highly regarded by their colleagues. It provides an enlightening change of viewpoint to return to a book, such as Loeb's Mechanistic Conception of Life, which views the lay and scientific worlds as inextricable.

Notes on the Notes

Professor Fleming has preserved the original text and index complete, so that we may know exactly what Loeb said and what he thought worthy of reference. Fleming has also supplied notes at the end of each chapter to bring the reader up to date on technical material. Such notes take the edge off Loeb's scientific dogmatism when, as is often the case, he is wrong.

The chapter on the comparative physiology of the central nervous system does require a minor addendum. On page 73, Loeb says that worms do not posses associative memory, that is, the capacity for learning. This was consistent with what was known when Loeb wrote the chapter in 1899. Months after he revised it in 1912, Robert Yerkes reported in the Journal of Animal Behavior an experiment that became famous: Yerkes trained a single earthworm over a period of months to learn a simple maze. Fleming's note at the end of the chapter mentions neither this nor more recent experiments in training planarians.

In all other respects, one can only be grateful to Professor Fleming for making Loeb's work available along with the other important documents of American thought in the John Harvard Library