Müller , Johannes Peter

(1801–1858) German physiologist

Müller, a shoemaker's son from Koblenz in Germany, graduated in medicine from the University of Bonn in 1822. He worked as a pathologist in Bonn until 1833 when he moved to the University of Berlin as professor of anatomy and physiology, a post he retained until his death.

Müller was the most important figure in 19th-century German physiology. Not only did he number among his pupils such figures as Hermann von Helmholtz, Carl Ludwig, Rudolf Virchow, and Max Schultze but those he did not teach were reached by his influential work, Handbuch der Physiologie des Menschen (2 vols., 1834–40; Handbook of Human Physiology).

It was in the field of neurophysiology that Müller made his major contribution to science. In 1831 he neatly and conclusively confirmed the law of Charles Bell and François Magendie, which first clearly distinguished between motor and sensory nerves. Using frogs and dogs, Müller cut through the posterior roots of nerves from a limb as they entered the spinal cord. The limb was insensible but not paralyzed. When however Müller severed the anterior root he found that the limb had become paralyzed but had not lost its sensibility.

He also worked on the cranial nerves and succeeded in showing that the first two branches of the trigeminal nerve are sensory while the third branch, to the jaw, contains motor fibers also. The vagus and the glossopharyngeal were, Müller claimed, mixed nerves.

Müller also formulated, in 1826, the law of specific nervous energies, which claimed that nerves are not merely passive conductors but that each particular type of nerve has its own special qualities. For example, the visual nerves, however they may be stimulated, are only capable of transmitting visual data. More specifically, if such a nerve is stimulated, whether by pressure, electric current, or a flashing light, the result will always be a visual experience.

After the completion of the Handbuch in 1840 Müller turned more to problems of anatomy and physiology. He worked with Robert Remak on embryological problems and was the first to describe what later became known as the Müllerian duct. This is a tube found in vertebrate embryos, which develops into the oviduct in females; it is found only vestigially in males. He also spent a large amount of time collecting and classifying zoological specimens.

Müller was much given to fits of depression, frequently feeling that his own creativity was exhausted. Consequently when he was found dead in bed, although no autopsy was ever performed, it was widely assumed that he had died by his own hand.