Childhood & Early Life
Johannes Peter Müller was born on 14 July 1801, in Koblenz, Germany, into a poor family. His father was a shoemaker.
Müller’s father wanted him to continue his family trade and was about to apprentice him to a saddler, when a Prussian educational reformer, Johannes Schulze, noticed Müller’s skills in mathematics and classical languages and persuaded Müller’s father to send him to the Bonn University.
In 1819, he enrolled in the Bonn University to study medicine. Three years later in 1822, he received his medical degree with a doctoral thesis on animal movement patterns, especially in insects.
He next studied at the Berlin University where he was encouraged to discard those systems of physiology which were not based on a careful study of nature. The Berlin anatomist Carl Asmund Rudolphi inspired him to take up microscopic studies.
Soon, he became an expert microscopist. In 1824, after he had passed the Prussian state medical examination and returned to Bonn, he received the Frauenhofer microscope from Rudolphi to carry out his future researches.
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Meanwhile, in October 1824, he delivered a lecture ‘Uber das Bedürfnis der Physiologie nach einer philosophischen Naturbetrachtung’ (On the Need of Physiology for a Philosophical Contemplation of Nature). In the lecture he defined his scientific strategy of merging careful observation of natural forms with limited philosophical theorization.
Through his years of research at Bonn he provided information in various segments of physiology, especially the voice, speech, hearing, visual, circulatory, endocrine, and reproductive systems. He also elucidated the chemical and physical properties of lymph and blood.
In 1826, he published ‘Zur vergleichenden Physiologie des Gesichtssinnes des Menschen und der Thiere’ (On the Comparative Physiology of Vision in Men and Animals). It described human binocular vision and the structure of insect eyes.
In 1826, he also published ‘Ueber die phantastischen Gesichtserscheinungen’ (On Fantasy Images), which was a study of optical illusions. His work showed that the visual system is active recorder of external events.
Through his studies of the nervous system, he elucidated that nerves are not merely passive conductors of outer stimuli. In ‘Handbuch der Physiologie des Menschen’ (Elements of Physiology), he explained that each nerve responds to stimuli only in a specific way.
He conducted detailed comparative studies of the endocrine and reproductive systems and these observations were published in ‘De glandularum secernetium and Bildungsgeschichte der Genitalien’ in 1830. He explained that glands, and not blood vessels, were responsible for secretions that control bodily functions. He also identified the blood vessels responsible for male erection.
He experimentally demonstrated physician Charles Bell’s and physiologist François Magendie’s theory that the dorsal roots of spinal nerves carry sensory fibres, whereas the ventral ones carry motor fibres.
In 1832, Rudolphi died and Müller expressed a desire to acquire the prestigious position of Berlin professorship. He finally received the position in 1833 and continued till 1858. He worked hard to make Berlin a center for comparative anatomical studies.
As a medical professor at Berlin, he taught physiology, human anatomy, sensory anatomy, comparative anatomy, and pathological anatomy. He also partly managed the medical students' dissecting laboratory and scrutinized Prussian candidates in quest of medical degrees.
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One of his biggest preoccupations at Berlin was to restore the university’s anatomical museum. He was passionate about gathering all known animal forms, in an effort to understand how life was organized.
Between 1833 and 1844, he consolidated his enormous physiological knowledge in the significant publication ‘Handbuch der Physiologie’. It went on to become the most important textbook in the field for much of the 19th century.
Meanwhile in 1834, he established the ‘Archiv für Anatomie, Physiologie und wissenschaftliche Medicin’. The prestigious journal contained annual reports on physiological and anatomical research progresses being made all over Europe. In 1834, he was also elected as a foreign member of the Royal Swedish Academy of Sciences.
After his assistant, Theodor Schwann demonstrated the cell as the basic unit of animal body, Müller studied the cellular structure of tumours with the help of a microscope. His observations were published in ‘Ueber den feineren Bau der krankhaften Geschwülste’ (On the Fine Structure of Pathological Tumours) in 1838.
He also distinguished marine organisms and developed a new classificatory system for the myxinoids (hagfishes) and plagiostomes (cartilaginous fishes such as sharks) in the late 1830s.
In the 1840s, he continued his research on marine organisms such as cyclostomes (lampreys) and ganoid (scaly) fishes. He researched in depth about the echinoderms - animals with radial symmetry such as starfishes.
Apart from teaching and conducting research, he also executed heavy administrative duties. He served as Dean of the Medical Faculty in 1835-36 and 1842-43, and Rector of the Berlin University in 1838-39 and 1847-48.
Throughout his career, he often suffered periods of severe depression. The final spell of hopelessness occurred after a harrowing shipwreck in 1855 in which one of his young students drowned. He felt personally accountable for the student’s death and never completely recovered from the guilt.
Even though he continued teaching and researching after this incident, his health began to deteriorate. He increasingly became dependent on opium to lessen his abdominal pains and fight insomnia.
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During his lifetime, he mentored various famous scientists and physiologists such as Hermann von Helmholtz, Emil du Bois-Reymond, Theodor Schwann, Friedrich Gustav Jakob Henle, Carl Ludwig, Ernst Haeckel, et al.
Müller’s most important discovery was his finding that each of the sensory organs responds to different kinds of stimuli in their own unique way. His research on vision elucidated that the eye as a sensory organ not only responds to external optical stimuli but also internal stimuli triggered by the imagination.
He studied the journey of impulses from afferent nerves to efferent nerves, further explaining the concept of reflex action. He thus confirmed the law named after Charles Bell and François Magendie.
His publication ‘Über den feineren Bau und die Formen der krankhaften Geschwülste’ (On the Nature and Structural Characteristics of Cancer and of Those Morbid Growths Which May Be Confounded with It) established pathological histology as an autonomous branch of science.
A bronze statue by Joseph Uphues was erected at Koblenz in 1899, in Müller’s memory.
Personal Life & Legacy
In April 1827, Müller married the gifted musician Nanny Zeiller.
He was fatigued from his full time teaching profession, wide-ranging researches, and the publication of books. In 1827, 1840, and 1848, he suffered bouts of depression that left him incapable of working for several months.
He died on 28 April 1858, in Berlin, at the age of 56. His recurrent depression is often speculated to be the cause of his death.