Jacques Loeb
Loeb argued that life phenomena, including development, regeneration, heredity and animal orientation, can be explained in physicochemical terms13. He induced membrane formation in unfertilized sea-urchin eggs with fatty acids2. He also proposed a continuous-action theory of tropisms5 and put instinct on a physiological footing6.
- Born
- 7 April 1859
- Died
- 11 February 1924
- Country
- Kingdom of Prussia
- Field
- physiologist, biologist, zoologist
- In the library
- 2 works, named in 12 passages elsewhere
- Facts from
- Wikidata · Wikipedia · Open Library
Mechanism and the whole organism
Loeb traced scientific biology to Lavoisier and Laplace, who equated the heat of an animal with that of a candle burning the same carbon1. He held that the organism as a whole needs no separate explanation. He said Claude Bernard separated individual processes from the harmony of the whole only because specificity, developmental physiology, Mendelian heredity and tropisms were not yet known3. In the egg work he reported that butyric acid made unfertilized eggs form a fertilization membrane as if a spermatozoon had entered2.
Tropisms and instinct
Loeb held that orientation of animals to light is like that of plants. It depends on the continuous action of light, not on changes in intensity5. Driesch credited Loeb with first putting instinct on a physiological basis6. Driesch also faulted this for treating complex movements as simple additive chains of reflexes. Child argued that tropisms as Loeb conceived them need more organismic pattern than trial reactions do7.
Specific claims and responses
Loeb suggested that pieces of cell without a nucleus fail to regenerate because oxidation is too low. Morgan cited this and opposed it with non-nucleated amoeba pieces that stayed alive for fourteen days4. William James reported Loeb's arm-movement observations: the more contracted arm made the shorter movement when the two seemed equal. Loeb read this as support for a feeling of innervation. James was not convinced8.
Scientific biology, defined in this sense, begins with the attempt made by Lavoisier and Laplace (1780) to show that the quantity of heat which is formed in the body of a warm-blooded animal is equal to that formed in a candle
Loeb, J., 1912 · The Mechanistic Conception of Life · open at passage 4Six years ago while experimenting on the Californian sea-urchin, Strongylocentrotus purpuratus, I succeeded in finding a method of causing the unfertilized egg to form a membrane without injuring the egg.
Loeb, J., 1912 · The Mechanistic Conception of Life · open at passage 12the phenomena of specificity, the physiology of development and regeneration, the Mendelian laws of heredity, the animal tropisms and their bearing on the theory of adaptation were unknown.
Loeb, J., 1916 · The Organism as a Whole, from a Physicochemical Viewpoint · open at passage 12Loeb ('99) has suggested that the lack of power of non-nucleated pieces may be due to a lack of oxidation.
Morgan, T. H., 1901 · Regeneration · open at passage 168Loeb maintains the view that the tropism or oriented response of animals to light is dependent on the continuous action
Washburn, M. F., 1908 · The Animal Mind: A Textbook of Comparative Psychology · open at passage 324Jacques Loeb was the first to see the inadequacy of both these methods, and to put the problem of instinct on its clear physiological basis.
Driesch, H., 1908 · The Science and Philosophy of the Organism · open at passage 87the tropisms, as conceived by Loeb, require a greater degree of development of organismic pattern and mechanism than do the trial reactions.
Child, C. M., 1924 · Physiological Foundations of Behavior · open at passage 596that movement always turns out really shorter which is made with the arm whose muscles (in virtue of the arm's position) are already the more contracted.
James, W., 1890 · The Principles of Psychology, Vols. 1-2 · open at passage 2887
