(b. Lyons, France, 2 October 1835; d. Vendranges, Loire, France. 22 March 1922)
Ranvier was the foremost histologist in France in the latter part of the nineteenth century. A student of Claude Bernard, he combined the German histological tradition with the French physiological tradition. Ranvier’s father, Jean-Françtjois-Vietor Ranvier, was a businessman who had retired early to devote himself to public administration.
After studying medicine at Lyons, Ranvier went to Paris, and passing the examination to become an intern, entered the Paris hospitals in 1860. He received his medical degree in 1865. Shortly thereafter he and a friend, Victor Cornil, founded a small private laboratory where they offered a course in histology to medical students. Continuing the work of the Paris clinical school on the microscopical level, Cornil taught pathological anatomy while Ranvier taught normal anatomy. From this collaboration resulted the Manuel d’histologie pathologique, a unique work in France, where the leading pathological anatomists still disdained the microscope.
Ranvier’s collaboration with Cornil ended in 1867 when Ranvier became préparateur for Bernard at the Collège de France. Ranvier made his lodgings there into a small histology laboratory, which in 1872 was annexed to Bernard’s chair of experimental medicine and given official recognition as the Laboratoire d’ Histologie of the École des Hautes Études. In 1875, through Bernard’s influence, Portal’s defunct chair of anatomy at the Collèege de France was recreated for Ranvier as the chair of general anatomy; and for a time the histology laboratories at the Ecole des Hautes Études and at the Collège de France were combined. But eventually the laboratories were separated, with Ranvier’s student Louis Malassez becoming director of the laboratory at the École des Hautes Études. In 1887 Ranvier became a member of the Academy of Sciences.
Ranvier’s teaching, which he conducted mainly in the laboratory, tended to be dryly technical and focused on his own research. He therefore attracted only a small audience, but his printed leçons were widely read. For several decades his Traité technique d’histologie (1875–1882) was a leading textbook in the field. At the beginning of his career, Ramón y Cajal took Ranvier’s text as his scientific “Bible.” From 1875 until about 1890 Ranvier’s laboratory was a center of activity for a large number of students, both French and foreign, including Malassez, Louis de Sinéty, Maurice Debove, Renaut, William Nicati, and E. Suchard. After 1890 biological research moved away from morphology to chemistry, physical chemistry, and microbiology. For several years thereafter (until 1895) Ranvier continued his work, producing particularly important studies on cicatrization and on the development of the lymphatic vessels. In 1897 he and Balbiani founded the Archives d’anatomie micro-seopique, the first journal in France devoted exclusively to microscopical studies. By 1900 Ranvier felt isolated from the scientific community in France and retired to his estate in Thélys, where he spent the next twenty-two years almost totally removed from the scientific scene. He never married.
When Ranvier began his career, histology was well established in Germany but little pursued in France. Because he inherited the physiological tradition established by Bernard, Ranvier’s work was not as strictly morphological as much of the work in Germany. He supplemented histological techniques with those of physiological experimentation, namely, ligation, excitation of nerves and muscles by electricity, nervous section, and graphical registration of movements. His biographers have looked upon his work as an extension into histology of Bernard’s method.
Ranvier’s work was noted for its precision, thoroughness, and simple but effective techniques. He preferred disassociations (or fine dissections) to sectional cuts; and whenever possible he worked with thin membranes that were naturally disassociated. His few sectional cuts were usually made by hand rather than with the microtome. Osmic acid, alcohol, and bichromates were his usual fixating agents. The remainder of his reagents included a few coloring agents for injections and solutions of gold and silver for impregnations. Most often Ranvier worked with adult tissues; he took little interest in histogenesis. Like Bernard, he had only contempt for statistics. Although he recognized the necessity of forming hypotheses in his experimental work, he disliked theorizing.
Ranvier’s work embraced all organic systems, but he is best known for his researches on the peripheral nervous system. His earliest and most celebrated achievement was his discovery in 1871 of the annular constrictions of medullated nerves, now known as the nodes of Ranvier. Ranvier showed that the medullated nerves are not regularly cylindrical—at approximately equal distances there are constrictions in the form of rings where the myelin sheath, but not the cylinder axis, is interrupted. The nodes divide the nervous fiber into interannulary segments possessing a nucleus and protoplasm (neurilemma nucleus). Ranvier prepared his specimens either by the osmic acid method first employed by Schultze or by impregnation with silver nitrate.
Ranvier also investigated the degeneration and regeneration of sectioned nerves. In spite of Waller’s earlier studies (1852), many scientists continued to believe that the cylinder axis persisted in the peripheral segment after section and therefore had an independent life. Ranvier’s work, confirming Wallerian degeneration, showed that the cylinder axis of the peripheral segment does fragment and disappear, while the cylinder axis of the central segment hypertrophies and emits buds that are the point of departure for new nervous fibers. Ranvier believed that regeneration of nerves was a particular case of the general law of growth from the center to the periphery.
Using an improved method of impregnation by gold, Ranvier did extensive research into the nervous terminations in the skin, the muscles, the cornea, and the sensorial organs. His other notable work on the nervous system includes a description of the “laminous sheath” (perineurium) connecting bundles of nervous fibers and his discovery that the apparently unipolar cells of the spinal ganglia of mammals bifurcate in a T-branch. This research tended to support the theory that the cylinder axis is a prolongation of the nervous cell. Much of Ranvier’s work on the nervous system was later used to support the neuron theory, but Ranvier himself did not become involved in the famous neuron-reticulum controversy. He did, however, support the controversial doctrine of the fibrillary structure of nerve cells.
Ranvier also studied the differences between the nervous terminations of voluntary and involuntary muscles. To study muscle contraction he devised a method for utilizing a spectrum of diffraction set up by an extended muscle, which he then subjected to a tetanizing current.
Ranvier studied the secretion of the salivary glands in the dog on a microscopical level. He obtained secretions by electric stimulation of the tympanic cord. He also investigated the nature of connective tissue and refuted Virchow’s theory by the novel method of disassociation by an edematous papule (boule d’oedème) He studied the problem of the origin of the lymphatics and invented a cardiograph for measuring the movements of lymphatic hearts.
Because Ranvier rarely discussed the theoretical implications of his works, he is almost unknown to historians today. Independent, unsociable, often rude, and seemingly insensitive, he was admired and feared more often than loved by his students and colleagues.
I. Original Works. Ranvier’s works include Manuel d’histologie pathologique (Paris, 1869; 2nd ed. 1881–1884), written with Victor André Cornil; and Traité technique d’histologie (Paris, 1875–1882; 2nd ed., 1889). Several of Ranvier’s courses at the Collège de France were edited and published: Leçons d’anatomie générale faites au Collège de France, par L. Raniver: Année 1877–1878. Appareils nerveux terminaux des muscles de la vie organique: coeur sanguin, coeurs lymphatiques, oesophage, muscles lisses, leçons recueillies par MM. Weber et Lataste; Année 1878–1879. Terminaisons nerveuses sensitives; cornée, leçons recueillies par M. Weber, 2 vols.(Paris, 1880–1881); Leçons sur l’histologie du système nerveux, par M. L. Ranvier, …recueillies par M. Ed. Weber, 2 vols. (Paris, 1878); Leçons d’anatomie generale sur le système musculaire, par L. Ranvier, …recueillies par M.J. Renaut (Paris, 1880). Exposé des titres et des travaux de M. L. Ranvier (Paris, 1885) was written by Ranvier to support his candidacy for the Académie des Sciences and is a useful source of information of Ranvier’s work.
The Royal Society Catalogue of Scientific Papers, V, 96; VIII, 699–700; XI, 104–105; and XVIII, 51–52, lists Ranvier’s memoirs through 1900. A more complete list can be found in Jolly. (See below.)
II. Secondary Literature. The most extensive biography of Ranvier is J. Jolly, “Louis Ranvier (1835–1922): Notice biographique,” in Archives d’anatomie microscopique, 19 (1922), i–lxxii, with bibliography. Jolly’s analysis of Ranvier’s work is largely based on Ranvier’s Exposé.…. Jolly, a student of Ranvier’s, also wrote “Ranvier et la methode expérimentale,” in Le Collège de France (1530–1930) (Paris, 1932), 209–219. See also J. Nageotte, “Louis-Antoine Ranvier,” in Comptes rendus des séances de la Société de biologie, 36 (1922), 1144–1152. The Isis Cumulative Bibliography contains a list of obituary notices on Ranvier.
Toby A. Appel