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Müller, Johannes Peter


(b. Coblenz, Germany, 14 July 1801; d. Berlin, Germany, 28 April 1858)

physiology, anatomy, zoology.

Müller introduced a new era of biological research in Germany and pioneered the use of experimental methods in medicine. He overcame the inclination to natural-philosophical speculation widespread in German universities during his youth, and inculcated respect for careful observation and physiological experimentation. He required of empirical research that it be carried out “with seriousness of purpose and thoughtfulness, with incorruptible love of truth and perseverance.” Anatomy and physiology, pathological anatomy and histology, embryology and zoology—in all these fields he made numerous fundamental discoveries. Almost all German scientists who achieved fame after the middle of the nineteenth century considered themselves his students or adopted his methods or views. Their remarks reveal his preeminent position in medical and biological research. Helmholtz, one of his most brilliant students, termed Müller a “man of the first rank” and stated that his acquaintance with him had “definitively altered his intellectual standards.”

Life . Müller came from a family of winegrowers in the Moselle Valley. His father learned shoemaking and moved to Coblenz, where he became fairly well-to-do. Müller distinguished himself as a student through his unusual gifts, methodical and assiduous work habits, and craving for knowledge. From the works of Aristotle to Goethe’s scientific writings, he devoured all the books he could obtain. His most striking trait was evident from childhood: a powerful ambition that drove him to be first, on the playing field as in the classroom. In the winter semester of 1819–1820 he entered the University of Bonn, which, founded in 1818, prided itself on being open to the latest intellectual currents. The Ministry of Education in Berlin had selected the professors chiefly according to their opinions of Schelling’s Naturphilosophie. Almost all the members of the Faculty of Medicine were adherents of the latter. Some embraced the Romantic belief in supernatural cures; others endorsed Mesmer’s animal magnetism.

During his second year at Bonn, Müler’s father died; and henceforth he had to appeal to his family, friends, native city, and the state for support. He then attracted the attention of Philipp Jakob Rehfues, curator of the University of Bonn, who assisted his academic career. Rehfues applied, on Müller’s behalf, to the authorities in Berlin—he could only give the grounds for such requests, not grant them himself—for stipends, travel allowances, and printing subsidies; later, money for vacations, remission of a loan, and a new microscope; and, finally, an increase in salary. Nevertheless Müller had financial problems even after he had become famous, since he unhesitatingly spent money for scientific purposes, for printing, and for books and instruments.

Müller received his medical degree in December 1822 and went to Berlin to continue his studies for another year and a half. In Berlin he came under the influence of Carl Rudolphi, Germany’s most distinguished anatomist. Rudolphi sought to lead scientific research out of the “turbid mire of mysticism” and endow it with an exact method. Müller credited Rudolphi with having enabled him to escape the dangers of natural-philosophical speculation and to cease adorning his writings with the fashionable vocabulary of electrical, magnetic, and chemical polarities, and positive and negative forces. In 1824 Muuml;ller passed the state medical examination in Berlin and then returned to Bonn, where in the same year he qualified as lecturer in physiology and comparative anatomy. A year later the Faculty of Medicine assigned him to lecture on general pathology as well. In 1826, not yet twenty-five years old, he became extraordinary professor; and in 1830 he was appointed full professor at an annual salary of 1,000 talers. In April 1827, after a long engagement, Müller married Nanny Zeiller of Coblenz; they had a daughter, Maria, and a son, Max.

The recognition that Müller enjoyed in the scientific world resulted in an offer from the University of Freiburg in 1832. He turned it down, even though it would have considerably improved his financial situation. He knew that Rudolphi was deathly sick and probably assumed that he would succeed him. Rudolphi died at the end of 1832. Since the Berlin Faculty of Medicine first offered the post to the Heidelberg anatomist Friedrich Tiedemann—who, however, did not accept it—Müller decided on a most unusual step for a German professor. In a letter to the Prussian minister of education, he proposed himself for the position and described the tasks that the holder of the Berlin chair of anatomy ought to fulfill. He must survey human, comparative, and pathological anatomy and must have done distinguished work in physiology, the foundation of all medicine. He must be familiar with microscopic observation, with experimental techniques in physioligy, and with studying problems from an embryological perspective. Furthermore, he must be able to attract and encourage talented students. All this was necessary if Berlin were to take its rightful place in the international competition for scientific predominance. He convinced the minister of the brilliance of his own attainments, and during the Easter season of 1833 he assumed the Berlin professorship of anatomy and physiology.

At Berlin, Müller lost interest in experimental physiology. The appearance of the last section of his two-volume Handbuch der Physiologie des Menschen in 1840 more or less marks this shift. Henceforth he devoted himself almost exclusively to comparative anatomy and zoology, especially to research on marine animals—down to the protozoans. In the last years of his life he also contributed to paleontology through his publications on fossil fish and echinoderms. He gathered the material for these studies on numerous expeditions in the North Sea and in the Mediterranean.

By 1834 Müller had become a member of the Prussian Academy of Sciences. In 1841 and in 1853 he received offers from the University of Munich, both of which he declined. He was elected rector for the years 1838–1839 and 1847–1848. This position burdened him with many difficulties during the Revolution of 1848. As rector he was caught between those students who longed for a new German Reich and those who demanded reforms in the university and in the state. At the same time, he stood between the government and the student body. Considering himself a loyal servant of the state, he did not contemplate a revolutionary change in the form of government and could not grasp the thinking of the students, who were filled with new ideals. Furthermore, he was dominated by the fear that the university, and with it the irreplaceable treasures of his anatomical collection, might go up in flames.

At the end of 1857 Müller complained of insomnia, with which he had been afflicted for years. He is reported to have wandered through backstreets in Berlin, driven by inexplicable anxiety. On the morning of 28 April 1858 his wife found Müiller dead in his bed. Since he had forbidden an autopsy, the cause of death remains unknown.

In his lifetime Müller experienced several periods of depression, which, like his periods of intense productivity, are traceable to a manic-depressive condition. The first depression, lasting for about five months, occurred in the summer of 1827. He was unable to work and ceased lecturing. The minister of education, when informed of Müller’s condition, granted him a leave of absence and provided him with money for a trip. In 1840 Müller again became depressed, but he did not suffer as much as the previous time. This depression may have been precipitated by his realization that he was no longer the leader in physiological research. He lacked a thorough knowledge of chemistry and physics, which was becoming a necessity in an age that had set out to investigate causal relationships among vital phenomena.

The depression that Müller experienced at the end of his year as rector in 1848 was far more serious. Incapable of working, he obtained an indefinite leave of absence, gave up his residence in Berlin, and fled with his family to Coblenz; but, unable to find peace in his native city, he traveled on to Bonn. In a state of extreme despair, he finally sought refuge in Belgium, at Ostend. He did not lecture during the winter semester of 1848–1849, returning to Berlin only at the end of March 1849. The end of his life was also marked by depression. He was obsessed by the fear that his field of research was exhausted and that his productivity was ended. Many of his contemporaries suspected that his sudden death was a suicide, a hypothesis that accorded with the clinical record of his depression. Ernst Haeckel, his last close student, had no doubt that he had ended his life with an overdose of morphine.

Physiology. Müller’s first publication and the doctoral dissertation based on it, De phoronomia animalium (1822), dealt with locomotion in animals. The investigation began with the movements of arthropods but continued in a comparative physiological manner, involving other classes of animals. He couched his excellent observations in terms of the doctrines of Naturphilosophie, which he had fully assimilated.

In 1820 the Bonn Faculty of Medicine posed its first prize question: Does the fetus breathe in the mother’s womb? Müller entered the competition and sought to clarify the problem through experiments on live animals. Experiments on pregnant cats were not successful. He was first able to demonstrate that the fetus breathes in an experiment on a ewe. Observing the umbilical cord, he ascertained that bright red blood flows to the fetus through the umbilical vein and that dark blood flows back to the placenta through the umbilical artery. Fetal respiration is one of the few problems that Müller solved through vivisection on warm-blooded animals. Later he had harsh words for this crude, “knife-happy” type of experimentation.

In 1826 Müller published an extensive work that attracted the attention of the scientific world: Zur vergleichenden Physiologie des Gesichtssinnes des Menschen und der Tiere nebst einem Versuch über die Bewegungen der Augen und über den menschliehen Blick. The book, in nine parts, reported on Müller’s various studies and interests. It opened with his inaugural lecture, “Von dem Bedürfnis der Physiologie nach einer philosophischen Naturbetrachtung,” in which he outlined his views on science at the time of his habilitation. The succeeding sections offered a wealth of new findings on human and animal vision, brilliant investigations into the compound eyes of insects and crabs, and truly perceptive analyses of human sight. Moreover, the book recorded the young physiologist’s most important achievement, the discovery that each sensory system responds to various stimuli only in a fixed, characteristic way—or, as Müller stated, with the energy specific to itself: the eye always with a sensation of light, the ear always with a sensation of sound, and so forth. This “law of specific nerve energies” led to the insight that man does not perceive the processes of the external world but only the alterations they produce in his sensory systems: “In intercourse with the external world we continually sense ourselves.” This statement had important implications for epistemology.

Later, in the Handbuch der Physiologie (4th ed., I 534), Müller maintained that all stimuli acting on the nerves have the same effect, whether they be mechanical chemical, thermal, or galvanoelectric; each nerve can react only with its “specific energy.” The reaction is determined by the properties of the stimulated organic substance, not by the quality of the stimulus. Müller conducted many experiments on isolated nerve-muscle preparations. Those on frog legs, employing galvanic electricity, were designed to determine the general conditions under which muscle contraction occurs. He utilized both changes in the galvanic stimulus and the effect of closing and opening the electric circuit. These experiments, along with those of Humboldt and Johann Wilhelm Ritter, constituted the first advances in electrophysiology. Matteucci’s research in this field led Müller to encourage his student Emil du Bois-Reymond to enter it.

Müller’s second book, Über die phantastischen Gesichtserscheinungen (1826), is still of interest. In it he showed that the sensory system of the eye not only reacts to external optical stimuli but also can be excited by interior stimuli arising from organic malfunction, lingering mental images, or the play of the imagination. He himself found it easy to make luminous images of people and things appear suddenly, move about, and disappear whenever he closed his eyes and concentrated on his darkened field of vision. With such self-observation and self-experimentation, supplemented with reports of earlier and contemporary authors—including Goethe, who in his scientific research likewise commenced from subjective experience—Müller demonstrated that optical perceptions can arise without an adequate external stimulus. When the stimulus is mistakenly assumed to have originated outside the body, the result— depending on the situation— is the reporting of religious or magical visions, or the seeing of ghosts.

Embryology . In the following years Müller’s research made him the most celebrated member of the Bonn Faculty of Medicine. During a period of extraordinary productivity he investigated problems of physiology, embryology, and comparative anatomy and was usually busy with several investigations at once. In 1830, under the title De glandularum secernentium structura penitiori earumque prima formatione, he published his studies on the emergence and structure of the glands; in the course of this research he employed anatomical preparations, injections, and especially the microscope. The book considerably fostered the advance of embryology and histology. In it he demonstrated that glands are invaginations of the covering membranes that are closed at one end and that blood vessels do not open into the glandular ducts but lie like capillaries in the walls of these ducts.

Simultaneously, Müller studied the origin of the omentum and its relation to the peritoneal sac (1830) in the human embryo and the embryonic development of the sexual organs in man and other vertebrates. In his Bildungsgeschichte der Genitalien he clarified the very complicated relationships between the initial form of the kidneys and their ducts, on the one hand, and the sexual organs, on the other. He discovered that the embryonic duct (described by Heinrich Rathke) now called “Müller’s duct” forms the Fallopian tubes, uterus, and vagina: only rudiments of it are found in the male.

Neurophysiology and Neurology . Müller was respon- sible for a remarkable advance in neurophysiology: confirmation of the Bell-Magendie law by means of a simple experiment performed on the frog. In 1822 Magendie had reported experiments indicating that the anterior roots of the spinal nerves conduct motor impulses outward, while posterior roots transmit sensations from the periphery to the central nervous system. Bell thereupon interpreted, in this sense, experiments that he had published in 1811, claiming priority of discovery. Unfortunately, in remarks made shortly afterward, Magendie partially retracted his findings. Since the research of several others had further complicated the situation, in 1831 Müller took up this important subject. At first he experi- mented on rabbits, but the work was difficult and yielded ambiguous results. Consequently he continued his investigation on frogs, the use of which in the laboratory had almost entirely ceased. In the frog the spinal cord was far easier to remove, the relationships between the nerve roots were much more apparent, and the results unambiguous and always reproducible. Cutting through the posterior roots leading to a hind leg, he found that the limb became insensible but was not paralyzed. When he cut through the anterior roots, however, he observed that the limb was paralyzed but not rendered insensible. The simplicity, conclu- siveness, and memorableness of the experiment— which has been repeated countless times in physiology courses—made a marked impression on Müller’s contemporaries. To be sure, Müller, who was driven by ambition throughout his life, did not hesitate to make his experiment widely known. In that very year (1831) he reproduced it in Paris for Cuvier and Humboldt and, in Heidelberg, for Tiedemann. He also had his friend Anders Retzius perform the experiment in Stockholm.

Closely related to the demonstration of the Bell- Magendie law were Müller’s efforts to determine the sensory and motor portions of the cranial nerves. He established experimentally that the first and second branches of the trigeminal nerve are sensory and that the third branch contains, in addition to sensory fibers, motor fibers for the jaw muscles. He also asserted, again on the basis of his own research, that the glossopharyngeal and vagus nerves are of the mixed type. In opposition to Magendie, however, Müller held that the hypoglossal nerve is of the motor type. This research led to the first comprehensive scientific conception of the nervous system as a unit. At the same time he postulated motor and sensory fibers for the autonomic nervous system; otherwise, it would be incapable of governing the intestinal functions under its control. Its motor function was demonstrated, he contended, by the fact that when a caustic is lightly applied to the celiac ganglion in the opened abdominal cavity of a rabbit the peristaltic movements of the intestine become far stronger.

In 1833 Müller studied the phenomenon of reflection, by which he meant the involuntary transition—occurring in the spinal cord or brain—of excitation from the centripetally conducting nerves to the centrifugally conducting ones. He took up this subject independently of Marshall Hall, who, shortly before Müller presented his results, had published On the Reflex Function of the Medulla Oblongata and Medulla Spinalis. … That the stimulation of an afferent or sensory nerve can provoke involuntary movements had already been asserted by Descartes. Müller provided the experimental proof that no communication exists between the afferent and efferent fibers, even though they are in the same nerve. Only the spinal cord or brain, he held, can mediate between the site of stimulation and the effector organ. According to Müller, the sensory organ, which receives the stimulus, can lie in the skin, the mucous membrane, or a muscle. As soon as the stimulus has reached the spinal cord, the impulse goes directly to the appropriate motor nerves—it does not pass up through the entire spinal cord: “The easiest path for the current or vibration of the nervous principle is from the posterior root of a nerve to its anterior root or to the anterior roots of several neighboring nerves.”He thought that the simplest type of reflex movement was the quick jerk with which one withdraws an injured limb when the skin has been burned. He also described coughing, sneezing, hiccuping, vomiting, and ejacu- lation as reflex arcs located along the spinal cord and medulla oblongata, thereby contributing a funda- mental new insight into the study of such phenomena.

To elucidate reflex action, physiology no longer had to fall back upon the old concept of “sympathies,”as Boerhaave had been constrained to do. Even Procháska, professor of anatomy and physiology at Prague and later at Vienna, who had observed the reflex mechanism in 1784, still spoke of the consensus nervorum or the “polar interaction of the organs."

Hall preceded Müller by some months in the publication of his Reflex Function, but he diminished the practical value of his observations by assuming the existence of a special “excitomotor”nervous system— leading only to the spinal cord—that supposedly carried stimuli to the central nervous system. With his reflex theory Müller was able to explain many processes in the human organism and was also able to demonstrate his ideas on animals—an achievement that his era, so fond of experimentation, considered of no less importance.

Handbuch der Physiologie . While at Bonn, Müller had planned to write a handbook of human phys- iology. The first section appeared in 1833, shortly before he moved to Berlin; the last section of the second volume was published in 1840. The work became a milestone in the history of European medicine. In Germany it established a fruitful interaction between physiology and clinical practice. Beyond a critical examination of the established knowledge of the subject, it furnished a wealth of new findings derived from his own work. Among the many topics in which Müller was able to draw upon the results of his own research, or upon his verification of the work of others, were the composition and coagu- lation of the blood, the origin of fibrin, the nature of lymph, the occurrence of the retinal image, the origin of the voice in the human and animal larynx, the propagation of sound in the tympanic cavity, the process of secretion, the nerves of the erectile sexual organs, and the function of the sympathetic nerve and other elements of the nervous system.

Müller’s Handbuch der Physiologie was a powerful stimulus to physiological research and one of the sources of the mechanistic conception of the life processes that prevailed in the second half of the nineteenth century. Yet the book’s fundamental tendency was vitalistic. For Müller, the cause and supreme organizer of life phenomena—the vital force (Lebenskraft)—acted in accord with the law of rational adaptation to function and had nothing in common with the forces of physics and chemistry. He attributed to this vital force the peculiar nature of the physiology experiment, which sets it apart from every other type. In the chemical experiment, both the reagents and the substance under consideration enter into the final product; in the result of a physiology experiment, however, the applied stimulus is by no means a more important component than is living nature: the result is determined solely by the vital energies of the organism. In whatever manner a muscle is stimulated, it always reacts with a contraction. A stimulus, however, can only provoke something fundamentally different from itself. This vitalistic tendency explains why Müller took a very critical view of the validity of physiological experi- mentation. Consequently, he underestimated the importance of Magendie, who must be considered the true creator of the techniques of experimental physiology.

The Soul . Müller’s Handbuch der Physiologie contains an extensive section on the soul (II, 505–588). This emphasis is understandable, in the light of his initial adherence to the ideas of Naturphilosophie. Starting from the philosophy and psychology of Aristotle, Giordano Bruno, Spinoza, Schelling, Hegel, and especially Herbart, he approached the questions of the identity of the psychic principle and the vital principle, the divisibility of the soul, and the seat of the soul. He arrived at the following alternative: The soul, which utilizes the organization of the brain in its activity, is either foreign to the physical body, not a force of organic nature, and only temporarily united with the body; or else it is inherent in all matter, a force of matter itself. Müller appears to have inclined more to the panpsychic conception when he wrote:

The relationship of the psychic forces to matter differs from that of other physical forces to matter solely because the spiritual forces appear only in organic and especially animal bodies, [whereas] the general physical forces, which are also called imponderables [light, electricity], are much more commonly active and widespread in nature. Since, however, the organic bodies take root in inorganic nature and draw their nourishment from it, … it remains uncertain whether or not the rudiments [Anlage] of psychic activities, like the common physical forces, is present in all matter and attains expression in a definite manner through the existing structures [brain and nervous system] [Handbuch, II, 553].

This panpsychism accounts for the fact that Müller considered the brain to be the seat of the soul but still suspected that it “might perhaps be more widespread in the organism.”To support this suppo- sition, he pointed out that lower animals like polyps and worms are divisible; and that therefore among such lower creatures, and thus in organic matter in general, the life principle and psychic principle can be separated.

Pathological Anatomy . At Berlin, Müller displayed a new interest in pathological anatomy as a result of his access to the holdings of the Anatomisch- zootomische Museum, which had come under his direction when he assumed his professorship. The surgeons of Berlin had contributed many operation preparations, tumors, and deformities. Through studying these specimens Müller realized that the traditional description of the external form of tumors could lead to no further advance. It had to be supplanted by the chemical analysis and microscopic examination of the pathological elements and by the study of their development. He saw the desirability of establishing a system able to distinguish between benign and malignant growths.

At the end of 1837 Müller’s student Theodor Schwann began working on his new cell theory, according to which the cells were the ultimate constituents of the animal body. On this basis Müller investigated pathological tumors, observing the similarity between the development of embryonic tissue and the formation of tumors from cells and showing that elements of normal tissue could be detected in the tumors. In 1838 he published the first, and only, part of his über den feineren Bau und die Formen der krankhaften Geschwüste. The publication of this work fostered the use of the microscope in the study of pathological formations. Müller thus founded pathological histology as an independent field and provided physicians with diagnostic procedures that are now used in daily clinical work. Several decades later his brilliant student Rudolf Virchow—to whom, in 1856, Müller entrusted the lectures on pathological anatomy at Berlin—greatly expanded research on pathological growths.

Zoology . After 1840 Müller devoted himself primarily to comparative anatomy and zoology, and his research in these fields made him the most respected scientist of his day. Collecting, describing, and classifying were now virtually the only methods he employed. He accomplished little of interest in physiological experimentation, which was by then drawing increasingly on the methods of physics and chemistry.

As early as 1832 Müller published a systematic classification of the amphibians and reptiles. In 1834 he turned his attention to the Cyclostomata, members of the most primitive class of vertebrates. In broadly conceived comparative anatomical studies, completed in 1842, he examined their skeleton and musculature, sensory organs and nervous system, and vessels and intestines. His considerations ranged from the muscles of the Cyclostomata to human trunk musculature and to the homology of the cranial and spinal nerves.

Müller placed the Cyclostomata among the fishes. He was thus led to study the sharks (which he called Plagiostomi) and the rays; he published the results of his research jointly with his student Jakob Henle as Systematische Beschreibunng der Plagiostomen (1841). A further product of this investigation was “Über den glatten Hai des Aristoteles”(1842). In Historia animalium, Aristotle had reported that the embryos of the “so-called smooth shark”are attached to the uterus of the mother by a placenta, as is the case among mammals. Rondelet had described such a shark in 1555 and Steno had observed one in 1673 off the coast of Tuscany, but it had not been referred to in more recent times. Müller was the first who was able to corroborate the earlier testimony.

In conjunction with the study of the shark, Müller constructed a natural system of the fishes based on work as painstaking as it was perceptive. He also devoted attention to the systematics of the songbirds, employing the vocal apparatus as his chief criterion of classification.

In the introduction to his account of the Cyclostomata Müller emphasized that the animals most apt to provoke the curiosity of the scientist are those “standing on the border of a class.”This was doubly true of the Cyclostomata because they stood at the border of the fishes and at that “of the verte- brates in general.”This curiosity led him to study the lancelet, especially the Branchiostoma lanceolatum. The latter could serve, Müller stated, as the simplest model of the basic plan of the vertebrate subphylum. A flexible member which serves as an axial skeleton, the Chorda dorsalis, extends through the animal’s body. This same skeleton is also found in the embryos of birds and mammals, The lancelet had been described in 1774, but Müller was the first to recognize its great systematic importance. In 1841, with Retzius at Stockholm—who had been his close friend since the Berlin scientific congress of 1828—he studied this primitive animal in Bohuslan, Sweden, and on the Felsen Islands near Göteborg and in the same year sent a description of it to the Prussian Academy of Sciences. This research, to which later work could add but little, became of great importance for knowledge of general vertebrate structure.

In his zoological research, Müller at first was satisfied to rely on the material in the collections available to him or that had been sent to him, but beginning in 1845 he traveled to the seashore to examine its animal life, especially the microscopic forms, in situ. During vacations he made many trips to the coasts of the North Sea and the Baltic, Adriatic, and Ligurian seas. He was rewarded with many unexpected results. In carefully executed studies, some of them lasting for years, Müller explored the echinoderms and sea slugs. Through observation and comparison he was able to elucidate their complex metamorphoses. He recognized the connection, bordering on the fantastic, between the double-ray larvae of the echinoderms, which are microscopic, transparent plankton animals, and the squat, five-ray, sexually mature animals of the same phylum. Thus, from the bilaterally symmetric larva that he named Pluteus paradoxus he was able to derive the radially symmetric sea urchin. In short, Müller not only opened this field, with its wealth of forms, to research but also penetrated its secrets conceptually. It is characteristic of the way he worked that he never attempted to clarify the development of the echi- noderms through experimentation, which might have led him to his goal more quickly.

These studies, which revealed the extraordinary creative powers of nature in a unique manner, received greater recognition than any of Müller’s previous achievements. He was awarded the Copley Medal of the Royal Society and the Prix Cuvier of the Académie des Sciences. His last research was devoted to the single-celled marine animals the Radiolaria and the Foraminifera. Haeckel continued this work.

Research Methods . Müller began his scientific career with vivisection in order to demonstrate that the fetus breathes in the uterus. He also utilized vivisection later when he was convinced that it could elucidate a question. Yet in setting forth his views on the study of living nature in his Bonn inaugural lecture, he stressed the technical difficulties of physiological experimentation and dissociated himself from the fondness for experiment characteristic of Magendie’s school. Müller’s scientific ideal was not Magendie or brilliant experimentalists like Haller or Spallanzani, but Cuvier, who devoted himself to the description and comparison of the forms and species of living creatures.

In the same inaugural lecture Müller spoke against the speculative interpretation of biological processes. Accordingly, he criticized the ideas of Natur philosophie, the temptations of which he had escaped through Rudolphi’s influence. He advocated a physiology that united ‘"exact empirical training”in all the methods suited to the investigation of living nature with a philosophical penetration of the data. Such a union, he claimed, would uncover the Urphänomene, the ideas underlying everything in the universe.

As he grew older, Müller expressed his methodology in much more modest terms in the Handbuch der Physiologie. He remained convinced that a strictly empirical approach to physiology could not solve the ultimate questions of life, but he conceded that philosophy could not yield results usable in an empirical science. Only a union of the two paths to knowledge, which he termed “critically evaluated experience”(“denkende Erfahrung”), could lead to scientific truth, although he added that there would

always he something unsolved. He no longer expressed the hope of penetrating to the Urphänomence. At Berlin, holding that the researcher’s principal instrument was “conceptual empiricism,”not experiment, Müller increasingly shifted his attention from functional to morphological issues. While his students sought to elucidate vital phenomena with the methods of physics and chemistry he was satisfied to describe them. In opposition to this new generation of scientists, he remained a vitalist throughout his life, never doubting the existence of the “vital force."


I. Original Works. A complete list of Müller’s 267 writings is in Abhandlungen der K. Preussischen Akademie der Wissenschaften for 1859 (1860), 157–175: it was reprinted in Koller’s biography (see below), pp. 241–260.

His works include De phoronomia animalium (Bonn, 1822); De respiratione foetus (Leipzig, 1823); Von dem Bedürfnis der Physiologie nach einer philosophischen Naturbetrachtung (Bonn, 1825), his inaugural lecture, repr. in Müller’s Zur vergleichenden Physiologie and in Adolf Meyer-Abich, Biologie der Goethezeit (Stuttgart, 1949), 256–281; Über die phantastischen Gesichts- erscheinungen (Coblenz, 1826), repr. in vol. XXXII of Klassiker der Medizin (Leipzig, 1927) and in Ülrich Ebbeeke, Johannes Müller (see below), 77–187; Zur vergleichenden Physiologie des Gesichtssinnes des Menschen und der Tiere nebst einem Versuch über die Bewegunfgen der Augen and über den menschlichen Blick (Leipzig, 1826); Bildungsgeschichte der Genitalien aus anatomischen Unter suchungen an Embryonen des Menschen and der Tiere (Düsseldorf, 1830); De glandularum secernentium structura penitiori earumque prima formatione in homine atque animalibus (Leipzig. 1830): and “Über den Ursprung der Netze and ihr verhältnis zum Peritonealsacke beim Menschen, aus anatomischen Untersuchungen an Em- bryonen,”in Archie für Anatomie und Physiologie (1840), 395–411.

See also “Bestätigung des Bell’schen Lehrsatzes dass die doppelten Wurzeln der Rückenmarksnerven ver- schiedene Funktionen haben, durch neue und ent- sehetdene Experimente”in Notizen aus dem Gebiete der Naturund Heilkunde30 (1831), 113–117; Handbuch der Physiologie des Menschen für Vorlesungen, 2 vols, (I. Coblenz, 1833–1834; 4th ed., 1841–1844; II, Coblenz, 1837–1840), also trans. into English by Baly, 2 vols. (London, 1840–1843) and into French by Jourdan, 2 vols. (Paris, 1845; 2nd ed., 1851); “Vergleiehenden Anatomie dei Myxinoiden (Cyclostomen),”in Abhandlungen der K. Preussischen Akademie der Wisscuschaften, Phys. Kl., for 1834, 1837–1839, 1843(1836–1845); Über den feineren Bau und die Formen der krankhaften GeschWülste (Berlin, 1838); Systematische Beschreibung der Plagiostomen (Berlin, 1841), written with Jakob Henle; “Über den glatten Hai des Aristoteles und über die Verschiedenheiten unter den Haifischen und Rochen in der Entwicklung des Eies,”in Abhandlungen der K. Preussischen Akademie der Wissen- schaften, Phys. Kl., for 1840 (1842), 187–257; and “Über den Bau und die Lebenerscheinungen des Branchiostoma lubricum Costa, Amphioxus lanceolatus Yarrell,”ibid., for 1842 (1844), 79–116.

Müller’s many publications on echinoderms began with his description of a sea lily—"Über den Bau des Pentacrinus caput Medusae,”in Abhandlungen der K. Preussischen Akademie der Wissenschaften, Phys. Kl., for 1841 (1843), 177–248— and was followed by eight papers on larvae, metamorphoses, and the structure of echinoderms, ibid., for 1846, 1848, 1850–1854(1848–1855).

II. Secondary Literature. Although the writings of du Bois-Reymond and Virchow on their teacher are limited by the thinking of their generation and do not always do justice to Müller, they are nevertheless indispensable: Emil du Bois-Reymond, “Gedáchtnisrede auf Johannes Müller,”in Abhandlungen der K. Preussischen Akademie der Wissenschaften, for 1859 (1860), 25–191, repr. with additional material in du Bois-Reymond’s Reden, 2nd ed., I (Leipzig, 1912), 135–317; and Rudolf Virchow, Johannes Müller. Gedächtnisrede (Berlin, 1858).

Among the more recent literature, see Wulf Emmo Ankel, “Branchiostoma ist ein Wirbeltier—eine 130 Jahre alte Erkenntnis,”in Natur und Museum, no. 101 (1971), 321–339; Ulrich Ebbecke, Johannes Müller, der grosse rheinische Physiologe (Hannover, 1951), which includes a reprint of Müller’s Über die phantastischen Gesichts- erscheinungen; Wilhelm Haberling, Johannes Müller. Das Leben des rheinischen Naturforschers (Leipzig, 1924), a detailed biography with letters from Müller to his family, friends, and colleagues; Gottfried Koller, Das Leben des Biologen Johannes Müller (Stuttgart, 1958), with a bibliography of secondary literature, pp. 261–263; Walther Riese and George E. Arrington, Jr., “The History of Johannes Müller’s Doctrine of the Specific Energies of the Senses,”in Bulletin of the History of Medicine, 37 (1963), 179–183; Robert Rössle, “Die pathologische Anatomie des Johannes Müller. Nach einem aufge- fundenen Kollegheft aus dem Jahre 1834,”in Sudhoffs Archiv für Geschichte der Medizin und Naturwissenschaften, 22 (1919), 24–47; Johannes Steudel, Le physiologiste Johannes Müller, Conférences du Palais de la Découverte, D85 (Paris, 1963); and Manfred Stürzbecher, “Auf dem Briefwechsel des Physiologen Johannes Müller mit dem preussischen Kulturministerium,”in Janus, 49 (1960), 273–284.

Johannes Steudel

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Johannes Peter Müller

Johannes Peter Müller

The German medical scientist Johannes Peter Müller (1801-1858) made important contributions to several branches of medicine, including anatomy, physiology, embryology, and pathology.

Johannes Müller the son of a shoemaker, was born in Coblenz, Rhineland-Palatinate, on July 14, 1801. He went to school in Coblenz before studying medicine at the University of Bonn from 1819 until 1822. At Bonn he was influenced by Naturphilosophie, including the belief that the smallest part of nature reflected grand themes running through the whole of creation. After taking his degree at Bonn, he spent 18 months in Berlin studying for the state medical examination. Although he never gave up his belief in a purposeful universe and the large generalizations of Naturphilosophie, he increasingly taught that experimental research was the way forward in medicine.

From 1824 until 1833 Müller taught medicine at Bonn, reaching the rank of professor in 1830. There his main achievements were in embryology and physiology. In 1825 he discovered the duct named after him and went on to make a pioneer study of the development of the genital glands in the embryo. He put forward a theory of color vision based on the study of a variety of animals and also investigated the way in which different nerves functioned.

In 1833 Müller became professor of anatomy and physiology and director of the Museum of Comparative Anatomy at the University of Berlin. He built up a famous school, and his students dominated German medical science in the second half of the 19th century. In 1833 Müller published the first part of his Manual of Human Physiology. It became the leading textbook on its subject and was revised and re-published many times. At Berlin he continued his research on nerve physiology but also undertook extensive investigations in comparative anatomy, writing large works on fishes and echinoderms. He was one of the first to make extensive use of the microscope in pathology, and in 1838 he published a volume on the pathology of tumors. In 1834 he had founded the journal known as Müller's Archiv.

Müller was rector of the University of Berlin during the revolutionary year of 1848, and the strain caused by the political upheavals impaired his health. In 1855 he was rescued from a sinking ship on a return voyage from Norway. He died in Berlin on March 28, 1858, without ever fully recovering from the shock of these two events.

Further Reading

A short account of Müller's life is in Henry E. Sigerist, The Great Doctors: A Biographical History of Medicine (1932). □

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Salomon, Johann Peter

Salomon, Johann Peter (b Bonn, 1745; d London, 1815). Ger.-born violinist and impresario. Played in Bonn court orch. 1758–65. Violinist and composer in royal orch. at Rheinsberg 1764–80. Settled in London 1781, winning special fame as qt. player. Began to organize concerts and introduced Haydn and Mozart syms. at series in 1786. Brought Haydn to Eng. 1790–1 and 1794–5 (hence name ‘Salomon symphonies’ for Haydn's last 12). Suggested The Creation to Haydn. Friend of Beethoven. Co-founder Phil. Soc. of London 1813, leading orch. at first concert. Comp. operas, oratorio, vn. concs. Buried in Westminster Abbey.

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Müller, Johannes Peter

Johannes Peter Müller (yōhän´əs pā´tər mŭl´ər), 1801–58, German physiologist and anatomist. From 1833 until the end of his career he was professor at Berlin. He was famed as a teacher; for his extensive research in many fields, including embryology, general and microscopic pathology, biochemistry, comparative anatomy, psychology, and marine zoology; and for his theories on color vision and voice production. As a result of his experiments in neurology he proposed the law of specific energies, i.e., that each sensory nerve produces its own specific sensation (e.g., any stimulation to the optic nerve results in a sensation of light).

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