Biographies de neurologues
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Johannes Müller
professeur de physiologie à l'Université de Berlin
Manuel de physiologie 1851
extrait de : John Talbott (1970)
A biographical history of medicine: excerpts ans essays ont the men


 Les biographies de neurologues
johannes muller
Johannes Müller professor at the University of Berlin in anatomy, physiology, and pathology, was one of the leaders of the 19th century school of physiology in Germany. He was born in Coblenz into a shoemaker's family, was educated in the faith of the Roman Catholic Church in a stormy period of European history, and at 10 years of age, entered a venerable Latin seminary of the Jesuits. Proficiency in Latin and Greek, skill in mathematics, and a self-developed interest in biology and zoology were forces which contributed to his turning from a life in the church to the medical sciences. After serving for a year as a volunteer in the army, in 1819 Muller began his higher education at the University of Bonn. The study of respiration of the fetus based upon experimental observations, which won him a prize in competition, was an early example of his abiding curiosity in the unraveling of physiological phenomena. He graduated MD from Bonn in 1822, presenting an inaugural thesis on the laws of motion. He then proceeded to Berlin to pass the state examination for a physician's license. While in Beilin, Müller made the acquaintance of Rudolphi, physiologist at the university, who spoke for recognition of the importance of anatomy in physiological investigation.
Müller returned to Bonn and established himself in private practice. He was impressed, nevertheless, with opportunities for the full-time professional pursuit of anatomy and the need to strengthen the union between natural philosophy and experimental physiology. In this endeavor, he became privatdocent on the faculty, took up the study of the sense organs and the nervous system, prepared a communication in Latin on the minute structure and anatomy of glands throughout the animal kingdom, and resolved a controversy between the adherents of Malpighi and Ruysch over the structure of glands. It was soon apparent that practice was not Müller's basic interest. Rather, he chose the academic road, where advancement was rapid and productive for him. Only three years after he received senior professorial status at Bonn, he applied for and was successful in obtaining the prized professorship of anatomy, physiology, and pathology vacated by Rudolphi upon retirement in Berlin. Müller remained in Berlin (meanwhile ignoring solicitations from other universities), until he resigned in 1848 while serving as rector of the university. He went into retirement, plagued by despondency and failing health. Because he died ten years later on his appointed day, the evidence suggests suicide. This act is partially understandable. In spite of his complete acceptance of experimental science, he was a dreamy mystic and proponent of the vitalistic theory, believing in the existence of a dynamic force insusceptible to mechanical or physical measurement.
Müller's interpretation of physiology, which exerted a profound influence on scientific medicine, was all-inclusive and embraced biology, comparative anatomy, chemistry, psychology, pathology, zoology, paleontology, and embryology. The number of scientific areas explored was surpassed only by the quantity and quality of his communications to scientific periodicals or prepared as monographs or texts. Several were translated into English for wider dissemination and easier accessibility. If Müller lacked one attribute in academic life, it was the charm of an engaging lecturer. The deficiency was minor, however; as if to compensate, his scientific "inspiration" profoundly influenced a number of brilliant pupils who were trained by him to reason as natural scientists. The list of followers includes Brücke, Du Bois Reymond, Helmholtz, Kölliker, Henle, and especially Schwann, who enunciated the cellular theory, and Virchow, the father of cellular pathology.
The first volume of Müller's most famous treatise, The Handbook of Human Physiology, appeared in 1834 and was translated into English in 1837. He summarized important advances in preceding decades and rendered current each subject, with integration of contributions made by chemistry and physical instruments. Consequently, physiology emerged under his leadership as a specific discipline among the medical sciences. Seizing every method of observation and utilizing mathematics and physics to investigate the intellect and the senses, he entertained the conviction that physiological investigation must exploit psychological understanding in interpreting mind and the soul. Although his law of specific nerve energies was propounded first at Bonn in 1826, his Physiology included a mature presentation of his conclusions.
«If the nerves are mere passive conductors of the impressions of light, sonorous vibrations, and odours, how does it happen that the nerve which perceives odours is sensible to this kind of impressions only, and to no others, while by another nerve odours are not perceived: that the nerve which is sensible to the matter of light, or the luminous oscillations, is insensible to the vibrations of sonorous bodies; that the auditory nerve is not sensible to light, nor the nerve of taste to odours; while, to the common sensitive nerve, the vibrations of bodies give the sensation, not of sound, but merely of tremours? These considerations have induced physiologists to ascribe to the individual nerves of the senses a special sensibility to certain impressions, by which they are supposed to be rendered conductors of certain qualities of bodies, and not of others.
A consideration of such facts could not but lead to the inference that the special susceptibility of nerves for certain impressions is not a satisfactory theory, and that the nerves of the senses are not mere passive conductors, but that each peculiar nerve of sense has special powers or qualities which the exciting causes merely render manifest.
Sensation, therefore, consists in the communication of the sensorium, not of the quality or state of the external body, but of the condition of the nerves themselves, excited by the external cause».
Müller supplied experimental proof in the frog for the Bell-Magendie doctrine of the function of spinal nerves, to wit: anterior roots carry centrifugal fibers and the posterior roots carry centripetal fibers. The correct experimental procedure was selected by Müller to support his physiological experience and intuitive judgment.
«The presence of sensory and motor nerves in the same trunk is one of the most important phenomenon in physiology. Charles Bell was the first to suggest that the posterior roots of a ganglion of the spinal nerves have only sensory functions and the anterior roots have only motor function, and that the fibers of these roots supply the skin and the muscles from one nerve tract.
Frogs seem best suited for the experiments; they withstand the exposure of the spinal canal, the nerves remain sensitive for very long periods, Sand the thick nerve roots of the lower extremities run a protracted and separate course in the spinal canal before they unite into larger trunks.
In each repetitive experiment we come to the conviction that irritation of the posterior root fails to produce the slighest contraction in the lower extremities. The same can be shown for the posterior roots that supply the upper extremities.
On the other hand, at the slighest stimulation of the anterior roots, the muscles twitch and contract. When the roots are separated from the spinal cord, any irritation produces energetic twitching».
The results of these experiments leave no doubt that Bell's law is valid and correct.
Another study in anatomy and physiology led to the discovery, in selecting amphibians, of four distinct hearts of the lymphatic system. The pulsating organs were encountered in the quest for frog lymph for demonstration to students. Posterior lymphatic hearts were identified first.
«These are most easily found in the frog, but they exist also in the toad, the salamander, and the green lizard; probably in all amphibia, the naked as well as those provided with scales. The organ is double, and, in the frog, lies on each side, behind the articulation of the os lemons, near the anus, in the regio iscniadica. The organ lies immediately under the skin Its regular contractions may be seen more distinctly when this is removed. The arteries and vena ischiadica, the largest vessels in the thigh, run immediately underneath the organ, but the motion of the blood in these vessels has no influence upon it. The contractions are neither synchronous with the motions of the heart, nor with those of the lungs . . . . They [contractions] continue after the removal of the heart . . . . The pulsations of the two organs, on the right and left sides, sometimes alternate at irregular intervals.
The anterior lymphatic hearts lie on each side, upon the great processus transversus of the third vertebra . . . . They are round in shape and connected with the contiguous vein. The fluid which is discharged into the vein is colourless».
In physiological chemistry, Müller isolated chondrin and gluten. In zoology, he studied the amphioxus, the starfish, sea cucumbers, and sharks; he became a paleontologist and studied fossil fishes, mammalia, echinites, and snails. In embryology, the paramesonephric duct (Müller's duct) was discovered by him in the developing chick. Müller's law of the eccentric projection of sensations from the peripheral sense organs to other nerve terminals, a theory of color contrast, and his work on strabismus and a comprehension of binocular vision represent borderline subjects between neurology and ophthalmology. An explanation of the color sensations (pressure-phosphenes), produced by pressure on the retina, was described in Physiology of Sight of Men and Animals.
«When pressure is applied with the finger tips to the lateral areas of the closed eyes, light rings appear in the periphery of the darkened field of vision. Lateral pressure on the right eye produces a light ring in the periphery on the medial side, and the lateral pressure on the left eye produces a light ring on the medial side of the field of vision. If the pressure is applied to the medial sides of either eye, the light rings appear again at the extreme periphery of the field of vision.
We conclude from these experiments that the retina of either eye is identical and forms one and the same subjective organ of vision; all parts lying in a certain meridian and at a certain distance from the central point of the eye are identical with the corresponding parts of the retina of the opposite eye, lying in the same meridian and at the same distance from the central point of the retina of that eye».
In demonstrating the harmony which existed between the pathological and the embryonic development of tumors, Müller was one of the first to employ the microscope. Until his time, the prevailing view considered cancer to be a general disease and the tumor a local manifestation. Müller showed that the cancer consisted of a growth of abnormal cells. He began a program of tumor identity, but death prevented its completion.
«According to Schwann, all the tissues in the embryo are formed from cells, which are themselves developed from nuclei; growth being the result of fresh formations of cells, which afterwards undergo transformation into other tissues. These observations led the author to examine morbid growths very carefully; both those in which no cells had hitherto been discovered, and also such as were known to present a cellular structure with a view to determine the presence of nuclei in the walls, or within the interior of the cells; while the author further hoped to verify the truth of that principle which Schwann has laid down. By employing a high magnifying power, cells were observed in many morbid growths in which they were not previously known to exist, as in collonema, in many varieties of carcinoma, and in enchondroma. In most growths presenting a cellular structure, with the exception of cholesteatoma and cellular polypi, the nuclei of the cells were discovered, situated either in their walls or in their interior: in many instances, too, young cells were formed within older ones, as was the case in sarcoma, enchondroma, carcinoma, and collonema. Thus, then, as might have been anticipated, did the examination of morbid structures confirm Schwann's observations touching the development and growth of healthy tissues.
Whether the carcinomatous diathesis be peculiar and distinct from all others, or whether, under certain circumstances, any other structure may pass into the state of carcinoma, still the same question presents itself;-is there any other characteristic of carcinomatous growths than such as are derived from their minute structure, or from the process of their development? The solution of this question must always be the grand problem in the anatomy of morbid growths. The examination of numerous specimens of carcinoma has taught the author that they, are, indeed, possessed of certain peculiar anatomical characters, which may serve to identify them; and, further, that these characters are distinguishable, on making a section of the growth, either by the naked eye, or at any rate by the aid of a common magnifying glass».
In 1834, Muller founded the Archiv für Anatomie, Physiologie und Wissenshaftliche Medicin, later known as Muller's Archiv. He was a member of almost all scientific bodies in Germany and of many foreign societies, including the Philosophical Society of Philadelphia and the American Academy of Arts and Sciences of Boston. He received the Copley medal of the Royal Society of London and was honored by the kings of Prussia, Sweden, Bavaria, and Sardinia.
1. Virchow, R.: Elogy of John nnes Muller (Ger), Berlin: A. Hirschwald, 1858, translated by A. M. Adam, Edinburgh Med J 4:452-463; 527-544 (July) 1858.
2. Müller, J.: Handbook of Human Physiology (Ger), Coblenz: J. Holscher, 1834-1840, translated by W. Baly, London: Taylor & Walton, 1837.
3. MüllIer, J.: Confirmation of Bell's Law (Ger), Notiz Geb Natur Heslk 30:113-122, 1831.
4. Müller, J.: On the Existence of Four Distinct Hearts, Having Regular Pulsations, Connected With the Lymphatic Sys,tem, in Certain Amphibious Animals (Ces), Philos Trans, pt 1, pp 89-94, 1833.
5. Müller, J.: Physiology of Sight of Men and Animals (Cor), Leipzig: K. Knobloch, 1826.
6. Müller, J.: On the Nature and Structural Characteristics of Cancer (Ger), Berlin: G. Reimer, 1838, translated by C. West, London: Sherwood, Gilbert, & Piper, 1840.
johannes muler