Jacques Loeb

Jacques Loeb, around 1915

Jacques Loeb (born April 7, 1859 in Mayen near Koblenz ; † February 11, 1924 in Hamilton on the Bermuda Islands) was a German-American biologist who, as one of the founders of the experimental research direction in biology that developed around 1880, of physiology. He was a representative of the extremely mechanistic or physico-chemical conceptions of the phenomena of life.

Life

Loeb came from the family of a Jewish businessman who felt strongly connected to France and its culture. After he lost his father and mother at the age of sixteen, he grew up with his uncle in Berlin and worked in his bank. He attended the Askanische Gymnasium in Berlin and from 1880 studied philosophy with Friedrich Paulsen . He broke off this course and then studied medicine in Berlin, Munich and Strasbourg . In Strasbourg he worked for the brain researcher Friedrich Leopold Goltz in his laboratory.

He received his doctorate in 1884 and passed his medical state examination in 1885. He then went back to Berlin and became an assistant to the physiologist Nathan Zuntz at the Agricultural University. In 1886 he moved to Würzburg and worked for the physiologist Adolf Fick . Here he made close contact with Julius Sachs , who founded the newer experimental plant physiology. In 1888 he went back to Goltz in Strasbourg. He worked several times at the zoological station in Naples .

An invitation to the Bryn Mawr College for women in Pennsylvania he accepted in 1891. From 1892 he took a position at the University of Chicago as a professor of physiology. He worked several times in the Woods Hole Marine Biology Laboratory . In 1902 he followed a call from the University of California, Berkeley , to switch to the Rockefeller Institute for Medical Research in 1910.

In 1909, on the occasion of its 500th anniversary, the University of Leipzig, together with Wilhelm Roux and Edmund B. Wilson, awarded him the title of honorary doctorate in philosophy. He was a co-founder of the Journal of General Physiology .

Loeb was nominated seventy-eight times for the Nobel Prize in Medicine or Physiology between 1901 and 1924 , but never received that award.

Loeb was married to the American Anne Leonard, whom he had met in Zurich.

Sinclair Lewis and Paul de Kruif created for him with their novel Dr. med. Arrowsmith is an enduring literary portrait.

Work and research

He took a strictly mechanistic view of life, according to which all life phenomena can be reduced to physical and chemical processes. Under the influence of the French materialists of the 18th century, he saw in living things a kind of chemical machine. Like Sachs, he also considered experimental research into the factors currently influencing living beings to be the most important task of biology and the resulting “physiological morphology” as a step forward over “formal morphology”. In his view, “physiological morphology” leads to a mastery of living nature, because that is the goal of science.

He thought dealing with the evolution of species made little sense. While still a student of Sachs, he transferred the theory of tropisms to animals via the directed movements of certain parts of plants (1888 and 1890). The flight of an insect towards the light or the light-dependent vertical movements of animals in the sea, as in the larvae of a balanus (barnacle) species he examined in Naples, should be chemically-physical through photochemical processes in the eye, subsequent nerve stimulation and the muscle contraction that this ultimately causes be quantitatively fully understandable. He recognized that individual stimuli guide the animals, so the flies to lay eggs z. B. be attracted only by a certain odor (i.e. by chemotropism ).

He also wanted to call simple reflexes tropisms , but this term did not catch on . During research on regeneration , the 1889/1890 found in Cerianthus , a polyp , that instead of a removed (extirpated) body part or organ, the same part does not have to regress, but a different structure can also arise. Loeb called this phenomenon heteromorphosis (1891), and its discovery stimulated new discussions about the development of germs. In 1892 he observed that isolated hydrocaulus pieces of Tubularia form new hydrant at both ends, but faster at the apical end than at the basal end. If the apical regeneration is prevented, the basal regeneration proceeds faster. The same could be achieved by lacing the hydrocaulus piece in its middle (1904). Loeb tried to explain his results with the assumption of “formative substances”, while Thomas Hunt Morgan assumed an inhibitory influence of the apical over the basal end.

His research on the influence of external factors such as light, oxygen and electrical waves on living beings was numerous. Loeb was one of the first to apply Svante Arrhenius' theory of ions to biology and researched (1897) the role of ions in life.

Loeb explained the specific effects of certain salts on the organism through the binding of the ions to the protoplasm and the resulting changes in the protoplasm properties. He dealt in depth with the "artificial parthenogenesis " discovered by Richard Hertwig and found numerous agents that stimulate an egg to develop instead of sperm (1899). In his simplistic view, Loeb saw processes of the same nature in the nerve excitation and developmental stimulation during fertilization - but not factually correct. By explaining the concept of fertilization, he believed he could come to an understanding of nerve excitation.

Most recently he researched the colloidal nature of proteins. In 1909 he met Otto Warburg in Heidelberg , whom he then supported financially in his research. With regard to humans, he said that “we owe our ethics to our instincts, which are chemically and hereditary in us in the same way as the form of our body” (1911). Loeb expressed the naive hope that the investigation of human behavior could one day enable it to be controlled and help to prevent irrational nationalist mass agitation as a cause of war. In the USA, Loeb was long considered the prototype of a modern biologist. In 1910 he was elected to the National Academy of Sciences , 1914 to the American Academy of Arts and Sciences and the Académie des Sciences in Paris.

Works

• The heliotropism of animals and its correspondence with the heliotropism of plants, 1890
• Investigations on the physiological morphology of animals, 2 volumes, (Volume I: On Heteromorphosis), 1891, 1892
• On a simple method of producing two or more fused embryos from one egg, 1894
• Introduction to Comparative Brain Physiology, 1899
• On the transformation and regeneration of organs, in: American Journal of Physiology , 4, 1900, pp. 60-68
• On the production and suppression of muscular twitchings, 1906
• Lectures on the dynamics of life phenomena, 1906
• The dynamics of living matter. New York 1906
• The chemical developmental excitation of animal eggs (artificial parthenogenesis). 1909
• The importance of tropisms for psychology. Lecture given on the VI. International Congress of Psychologists in Geneva 1909 Leipzig, 1909
• The life. Lecture at the 1st Monisten Congress , Hamburg, September 10, 1911. Leipzig 1911
• The mechanistic conception of life. Chicago 1912. Reprint, ed. Donald A. Fleming. Cambridge (Massachusetts) , 1964
• Is species-specifity a Mendelian character ?, in: Science , 45, 1917, pp. 191-193
• Regeneration from a physico-chemical viewpoint. 1924
• The protein bodies. Berlin 1924

literature

• H. Fangerau: Spinning the scientific web. Jacques Loeb (1859-1924) and his program of international basic biomedical research. Akademie Verlag, Berlin 2010
• H. Fangerau, I. Müller: National Styles? Jacques Loeb's Analysis of German and American Science Around 1900 in his Correspondence with Ernst Mach . In: Centaurus - International Journal of the History of Mathematics, Science, and Technology . 47 (2005), No. 3, pp. 207-225
• Ilse Jahn : history of biology . 2004, p. 454
• Irmgard Müller:  Loeb, Jacques. In: New German Biography (NDB). Volume 15, Duncker & Humblot, Berlin 1987, ISBN 3-428-00196-6 , p. 17 f. ( Digitized version ).
• Philip J. Pauly: Controlling Life: Jacques Loeb and the Engineering Ideal in Biology . Oxford University Press, New York 1987

Individual evidence

1. ^ H. Fangerau: The novel Arrowsmith, Paul de Kruif (1890-1971) and Jacques Loeb (1859-1924): A literary portrait of "medical science" , Medical Humanities 32 (2006), pp. 82-87
2. ^ List of members since 1666: Letter L. Académie des sciences, accessed on January 15, 2020 (French).