Jacques Loeb

Jacques Loeb ( born April 7, 1859 in Mayen near Koblenz, † February 11, 1924 in Hamilton, Bermuda ) was a German -American biologist who, as one of the founders of approximately 1880 developing experimental research direction in biology physiology, applies. He was a representative of the extremely mechanistic and physicochemical interpretations of the phenomena of life.

Life

Loeb was born into the family of a Jewish businessman who felt strongly connected with France and its culture. After he lost his father and his mother at the age of sixteen, he was raised by his uncle in Berlin and worked in the bank. He attended in Berlin the Askanische high school and studied from 1880 Philosophy of Friedrich Paulsen. He broke from this study and then studied medicine in Berlin, Munich and Strasbourg. In Strasbourg, he worked at the Friedrich Leopold Goltz brain researcher in the laboratory. In 1884 he received his doctorate in 1885 and put his medical state examination. Then he went back to Berlin and became an assistant to the physiologist Nathan Zuntz at the Agricultural College. In 1886 he moved to Würzburg and worked at the physiologist Adolf Fick. Here he took a close contact with Julius Sachs, who founded the recent experimental plant physiology. In 1888 he went to Strasbourg back to Goltz. Several times he worked at the Zoological Station in Naples.

One invitation to the Bryn Mawr College for Women in Pennsylvania, he followed in 1891. From 1892 he took a position at the University of Chicago as Professor of Physiology. Several times he worked in the Hole Marine Biological Laboratory Woods. In 1902 he was appointed professor of the University of California, Berkeley, to change around 1910 at the Rockefeller Institute for Medical Research.

1909 awarded him the University of Leipzig on the occasion of their 500th anniversary, along with Wilhelm Roux and Edmund B. Wilson the title of Honorary Doctor of philosophy. He co-founded the Journal of General Physiology.

Sinclair Lewis and Paul de Kruif created him with her novel Dr. Arrowsmith a lasting literary portrait.

Work and research

He represented a strictly mechanistic conception of life, according to which all phenomena of life on physical and chemical processes are reducible. Under the influence of the French materialists of the 18th century, he saw the creatures a kind of chemical machinery. How Sachs, he also held the experimental exploration of the creatures currently influencing factors for the most important task in biology and the resulting solid " physiological morphology " for an advance on the " formal morphology ". In his view, the lead " physiological morphology " To Mastering The living nature, because that is the goal of science.

The study of the evolution of species he considered little sense. While still a student of Sachs He aired Tropismenlehre on the directional movements of certain parts of the plants to the animals (1888 and 1890). The flight of an insect to the light or the light-dependent vertical movements of animals in the sea, as in the examined him in Naples larvae of Balanus ( barnacles ) nature, should be chemically and physically by photochemical processes in the eye, subsequent nerve impulses and thereby eventually caused muscle contraction be quantitatively fully understood. He recognized that individual stimuli of guiding animals, the flies to lay eggs themselves eg can attract only by a particular odor (ie chemotropism ).

Even simple reflexes he wanted to be called tropisms, but did not sit through this designation. In studies on the regeneration of the 1889/1890 took place at Cerianthus, a polyp that instead of a wegoperierten ( extirpated ) body part or organ does not have to regress the same part again, but can also have a different structure arise. Loeb called this phenomenon heteromorphosis (1891 ), and their discovery stimulated new discussions on the development of germs. He observed in 1892 that form isolated Hydrocaulus pieces of Tubularia at both ends new hydranth, but at the apical end faster than the basal. Prevents you the apical regeneration, so runs the basal faster. The same could be by lacing the Hydrocaulusstückes in its middle reach ( 1904). Loeb tried with the assumption to explain his results " formative substances ", while Thomas Hunt Morgan of an inhibitory influence of the apical went out on the basal end.

Many were his research on the influence of external factors such as light, oxygen, and electric waves on living organisms. As one of the first Loeb turned to the ion theory of Svante Arrhenius on the biology and explored (1897 ) the role of ions in life events.

The specific effects of certain salts on the organism Loeb explained by the binding of ions to the cytoplasm and thus triggered changes in the protoplasm properties. Incoming he dealt with the discovered by Richard Hertwig " artificial parthenogenesis " and found numerous agents that stimulate an egg to develop instead of sperm (1899 ). In the nervous excitement and development stimulation at fertilization Loeb saw in his simplistic approach - but objectively not applicable - consubstantial operations. He believed Through education fertilization, to gain an understanding of nervous excitement.

Most recently, he conducted research on the colloidal nature of the proteins. In Heidelberg he met Otto Warburg in 1909, whom he subsequently also financially supported in his research. In relation to man he said, " that we have an ethic that we owe only our instincts, which are defined in the same way chemically and hereditary in us as the shape of our body " (1911 ). Loeb expressed the naive hope that the study of human behavior could even be used to command and help prevent irrational nationalist Massenaufputschung as a cause of war. In the U.S., Loeb was long regarded as the prototype of a modern biologists.

Works

  • Studies on the physiological morphology of animals, 2 volumes, ( Volume I: About heteromorphosis ), 1891, 1892
  • A simple method to produce two or more coalesced embryos from an egg, 1894
  • Introduction to comparative brain physiology, 1899
  • On the transformation and regeneration of organs, in: American Journal Physiology, 4 ( 1900) 60-68
  • On the production and suppression of muscular twitchings, 1906
  • Lectures on the dynamics of the phenomena of life, 1906
  • The dynamics of living matter, New York, 1906
  • The chemical excitation of the development of animal eggs (artificial parthenogenesis ), 1909
  • Is species - specifity a Mendelian character, in: Science 45 (1917 ), 191-193
  • Regeneration from a physico- chemical viewpoint, 1924
  • The protein bodies, Berlin 1924
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