Jaques Loeb

(1859 - 1924)

Compiled by Jason Micenko (May 1999)

Loeb Biography
Time Line

In the early years on animal psychology in the United States, there was not a great deal on interest in the animal's consciousness. Romanes and Morgan were the pioneers of early animal, or comparative psychology. Jacques Loeb made a giant step toward objectivity in animal psychology. Loeb reacted against Romanes tradition of anthropomorphic, and his method of introspection by analogy, Loeb developed a new theory of animal behavior called tropism, or forced movement. Loeb was the third major figure in animal psychology, he was also a Physiologist and Zoologist from Germany. Jacques Loeb was born of a Jewish family in Rhine Providence of Prussia in 1859. Loeb's father was a prosperous merchant, an ardent Francophine and an admirer of the Enlightenment and French Revolution, he encouraged Jacques to read eighteenth century classics of free thought. When Loeb went to college he had intentions of becoming a philosopher. In 1880 Loeb entered the University of Berlin for Philosophy, after some time he thought that the Philosophy professors weak and just talked about the problems instead of solving them. So then Loeb switched his concentration to Biology. Later on during the 1880's Loeb went to work with Goltz at the University of Strasbourg on localization of the function of the brain which was intended to "starting point for an experimental analysis of the will."

When Loeb started out he was destine to find if there was any such thing as a freedom of will? Loeb was very much appealed of Sachsian tropism of plants and was bound up with his highly equivocal attitude toward Darwin. Loeb believed that the phenomena of life could be explained in terms of physical and chemical laws.


Loeb became involved in Psychology when he compared the activity of animals with the tropism effect of plants. He found that animals are structured so that they would react to certain kind of energy - mechanical and chemical. Loeb developed a theory of animal behavior based on the concept of tropism, an involuntary forced movement. He found that an animal's response is a direct and autonomic function of a reaction to a stimulus. In other words, behavior is said to be forced by a stimulus, it does not require any explanation in terms of an animal's consciousness. Loeb's theory was very influential for the time of Biological sciences, which represented a change from the work of Romanes and Morgan. At the time Loeb's work was viewed as an objective and mechanistic approach to animal Psychology. Loeb argued that the consciousness among animal's was by association of memory, which is when and animal learns to act to a desired stimuli in a certain or desired way. He used examples of jellyfish, starfish, and worms, then with his findings he extended the results to higher forms of life. He did not deal with human behavior but of human consciousness. His question, whether or not a particular species was capable of associative memory, if so, would it have consciousness. Otherwise in Loeb's mechanistic system the mind reacts throughout the association of ideas while still being invoked (1918).

In addition to his work on the physiology of the brain and animal tropisms, Loeb studied the regeneration of tissue and life span. He is noted for his argument that the phenomena of life can be explained in terms of physical and chemical laws. And, he made important contributions to the theory of colloidal behaviour of proteins. Graph

Time Line
1859 - born in born in Mayen, Germany
1880-84 - earned M.D. at the University of Strasbourg
1886-88 - worked in Biology at University of Wurzburg
1888-96 - continued Biology at the University of Strasbourg where his controversial research on caterpillars (1888) demonstrated that animals, like plants, possess similar mechanistic physiological responses (tropisms) to environmental stimuli.
1889-91 - worked at Naples Biological station
1890 - conducted important research on sea urchins, discovering artificial parthenogenesis in sea urchin eggs
1890 - married an American, Anne Leonard (a Ph.D. in Philosophy)
1891 - migrated to America at the age of 32 to teach at Bryn Mawr College (PA)
1893 - released paper "On some facts and principles of physiological morphology"
1892 professor at University of Chicago
1902 professor at University of California, Berkeley
1910-24 professor of physiology at the Rockefeller Institute for Medical Research where his studies on protein chemistry revealed that proteins can react as acids or bases.
1911 - won at the First International Congress of Monists
1912 - published his classic text, The Mechanistic Conception of Life 1924 - Jacques Loeb dies

Schultz, D. (1981) A History of Modern Psychology, Third Edition, New York, Academic Press.
Schults, D. (1992) A History of Modern Psychology, Fifth Edition, New York, Harcourt Brace Jovanovich College Publishers
Lundin, R. W. (1996) Theories and Systems of Psychology, Fifth Edition, Massachusetts, D. C. Heath and Company
Loeb, J. (1964) The Mechanistic Conception of Life, Massachusetts, The Belknap press of Harvard University Press

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