Johannes Müller

Johannes Peter Müller (14 July 1801 – 28 April 1858), was a German physiologist, comparative anatomist, ichthyologist, and herpetologist, known not only for his discoveries but also for his ability to synthesize knowledge.

He became Privatdozent of physiology and comparative anatomy at Bonn in 1824, extraordinary professor of physiology in 1826, and ordinary professor in 1830. In 1833 he went to the Humboldt University of Berlin, where he filled the chair of anatomy and physiology until his death.

In the century preceding Müller's work, many contributions to physiological science had been made. Müller gave order to these facts, developed general principles and showed physiologists how recent discoveries in physics and chemistry could be applied to their work. The appearance of his magnum opus, Handbuch der Physiologie des Menschen, between 1833 and 1840 (translated into English as “Elements of Physiology” by William Baly, and published in London 1837–1843) marked the beginning of a new period in the study of physiology. In it, for the first time, the results of human and comparative anatomy, as well as of chemistry and other departments of physical science, and tools like the microscope, were brought to bear on the investigation of physiological problems.

The most important portion of the work was that dealing with nervous action and the mechanism of the senses. Here he stated the principle, not before recognized, that the kind of sensation following stimulation of a sensory nerve does not depend on the mode of stimulation but upon the nature of the sense organ. Thus light, pressure, or mechanical stimulation acting on the retina and optic nerve invariably produces luminous impressions. This he termed the law of specific energies of the sense.

The book became the leading textbook in physiology for much of the nineteenth century. It manifests Müller’s interests in vitalism, philosophy and scientific rigor. He discusses the difference between inorganic and organic matter. He considers in detail various physiological systems of a wide variety of animals, but attributes the indivisible whole of an organism to the presence of a soul. He also proposes that living organisms possess a life-energy for which physical laws can never fully account.

Edward Forbes F.R.S. in his A History of British Starfishes, and Other Animals of the Class Echinodermata (1841) in his preface refers to Muller as the "one of the greatest living physiologists, Muller of Berlin".

In the later part of his life he chiefly devoted himself to comparative anatomy. Fishes and marine invertebrata were his favorite subjects. He took 19 trips to the Baltic and North Sea, the Adriatic and the Mediterranean to investigate salt-water life.

He authored a comprehensive work on the anatomy of amphibians, which in his era including reptiles. Also, he described several new species of snakes.

Müller mentored such distinguished scientists and physiologists as Hermann von Helmholtz, Emil du Bois-Reymond, Theodor Schwann, Friedrich Gustav Jakob Henle, Carl Ludwig and Ernst Haeckel. In 1834, he was elected a foreign member of the Royal Swedish Academy of Sciences.

Müller died in Berlin in 1858. In 1899, a bronze statue was erected in his memory at Koblenz.