Loeb

Jacques Loeb is dead--the greatest exponent Since Haeckel of what he called "the mechanistic conception of life." And because Loeb lived in the age of rigorously experimental biology, he contributed far more to the scientific verification of materialistic theories than did the greatest iconoclasts of an earlier day. The thesis to which he 'devoted his life of research might be stated briefly thus: "The activities as well as the origins of all living organisms, including human beings, are determined and motivated by physicochemical forces in their environments or inheritance." His experiments in support of this lay in two main directions:

Artificial Fertilization. Biologists had long known that certain low invertebrates, such as rotifers or plant lice, normally reproduce themselves without fertilization by the male, by a process called parthenogenesis (virgin birth). Loeb proved that in many other species parthenogenesis can be induced artificially by treating the egg in various ways, i.e., keeping it in sea water, in salt or sugar concentrations at a certain temperature, in certain acid solutions, pricking it with a needle. In 1899 he caused the unfertilized eggs of sea-urchins to 'develop into swimming larvae and remain alive. Similar results were obtained with starfish, worms, mollusks. In 1916 he developed full-grown frogs (a highly organized animal) of both sexes, by the same artificial process. His frogs were not limited to a single sterile generation, but continued to have offspring. Specifically, said Loeb, individual life begins with the acceleration of the rate of oxidation in the egg, and ends with the cessation of oxidation.

Tropisms or Forced Movements. Loeb discovered that many animals, as well as plants, contain in their eyes and sometimes in their skin, photosensitive substances which are chemically altered by light. The products formed influence the contraction of the muscles. If the animal is illuminated on one side only, it is compelled to turn in the direction of the light and move forward in a straight line. Thus the marine worm is "positively heliotropic" (to sun-light). These reactions are quantitatively graded to the strength and distance of the light.

Carrying out the broader applications of tropisms, Loeb says: "Our wishes and hopes, disappointments and sufferings have their sources in instincts which are comparable to the light instinct of the heliotropic animals. The need of and the struggle for food, the sexual instinct with its poetry and its chain of consequences, the maternal instincts with the felicity and the suffering caused by them, the instinct of workmanship, and some other instincts are the roots from which our inner life develops. For some of these instincts the chemical basis is at least sufficiently indicated to arouse the hope that their analysis from the mechanistic point of view is only a question of time."

Dr. Loeb was born in Germany of Jewish ancestry in 1859. He studied at Berlin, Munich, Strasbourg, received the degree of M. D. from the latter University in 1884. He taught physiology in various European institutions and conducted researches at the Naples Zoological Station, where he met and fell in love with an American girl student, Anne L. Leonard, of Easthampton, Mass. Upon their marriage in 1891, he came to the U. S., became an instructor at Bryn Mawr College. From 1892 to 1903 he taught at the University of Chicago, rising to the professorship of physiology, and then went to the University of California. In 1910 he became a member of the Rockefeller Institute for Medical Research, Manhattan, and was, until his death, head of the division of general physiology there. He was perhaps as widely known internationally as any American scientist, receiving honorary degrees from Cambridge, Geneva, Leipzig, and being honored with membership in scores of scientific societies in the U. S., England, France, Germany, Austria, Netherlands, Belgium, Russia, Italy. He was a prolific author and editor of books and periodical literature, his more; important full-length works including: Physiological Morphology; Comparative Physiology of the Brain and Comparative Psychology; The Dynamics of Living Matter; The Mechanistic Conception of Life; Artificial Parthenogenesis and Fertilization; The Organism as a Whole; Forced Movements, Tropisms and Animal Conduct; The Chemistry of Colloids.

Dr. Loeb died in Bermuda, whither he was accustomed to go annually for research in his marine laboratory there. He leaves, besides Mrs. Loeb, a daughter and two sons.