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Legallois, Julien Jean César

Legallois, Julien Jean César

(b. Cherrueix, near Dol, France, 1 February 1770; d. Paris, France, 10 February 1814),


Legallois was the first of the great French Phyiologists who based their conclusions on animal experiments. (He was followed by Magendie, Flourens, Claude Bernard, and Brown-Séquard, among others.) He is chiefly remembered as the first to localize the respiratory center in the medulla and as one of those who anticipated the internal secretions.

Legallois was the son of a Breton farmer who is said to have worked his land himself. The boy’s mother died when he was very young, but his father secured him a good education. His father died when Legallois was thirteen and a student at the Collège de Dol; he received a modest inheritance that he used to further his education. He won first prize in rhetoric at Dol and then began to study medicine at Caen. His career, however, was interrupted once by illness and again, after he recovered, by his involvement as a student leader in an armed movement in support of the federalists. After the defeat of his party, Legallois returned home to escape punishment but was denounced by a relative and fled to Paris. There he remained unnoticed among the crowed of young men trying to learn medicine in the hospitals after the abolition of the medical faculties.

Denounced a second time, Legallois braved his fate, and presented himself to the Comité des Poundres et Salpêtres. He proved himself satisfactory to the committee and was sent to organize and direct the manufacture of gunpowder in his native district. The following year, after the foundation of the école de Santé, Legallois, who had distinguished himself by his accomplishments, was delegated by the district committee to go to Paris as a wage-earning student. Besides medicine he studied Greek, Italian, and English, graduating in 1801. His dissertation was addressed to the question of whether blood is identical in all vessels through which it flows. In it Legallois pointed out that although blood is identical in all the arteries, it changes as it passes through the various organs and thus one organ may by its products influence all the others. This dissertation revealed Legallois’s interest in experimental physiology and was widely appreciated as a model of physiological discussion.

Even before his graduation Legallois had acquired great experience in practical medicine through working in hospitals for some ten years. While preparing his dissertation he realized the importance of experimental inquiry. For this reason he devoted much of his energy after he qualified to physiological research, although he had no official position in that field. For about ten years he served as physician to the poor of the twelfth civil district of Paris. He wrote two medicohistorical surveys (one on the discovery of galvanism and one on the chronology of Hippocrates) and a review of data on the contagious nature of yellow fever. He then began a long series of physiological experiments to determine the conditions basic to maintaining the life of any part of the body or, indeed, of the organism as a whole—in short, what he called “the principle of life.”

A clinical observation led him to speculate about how long a newborn, fully developed fetus might live without breathing. He was inspired in part by the experiments made by Lavoisier and Laplace in connection with the generation of animal heat and its relation to respiratory exchange, but soon he noticed that life closely depends on two functions, those of the nervous system and the circulation of the blood. Having noted that the interruption of circulation at some specific point led to the death of the part of the body affected, and that stoppage of the heart caused the death of the whole animal, Legallois formed his remarkable idea that it should be possible to maintain life by a sort of injection, “and if there be a continuous supply of arterial blood, natural or artificially prepared—provided such a procedure be possible—life of any portion could be indefinitely maintained…, even in the head after decapitation, with all the functions proper to the brain.” He pointed out in this way life could be reestablished in a part reduced to a state of apparent death after the cessation of circulation. At a time when profuse bloodletting was the therapeutic procedure of choice, Legallois’s idea of revival (or “resurrection,” as he called it) through bringing arterial blood to the tissues was an outstanding one. Although he reached his conclusion from physiological experiments, the technique was developed and applied in practical medicine only much later.

In spite of his severe myopia and short, thick fingers, Legallois was very skillful in experiments on living animals. His general approach was equally important. He recognized both the possibilities and the limitations of the experimental method as well as the conditions that must be observed to reach valid results. He therefore stressed the importance of the choice of animals and the necessity of the controls being of the same species, sex, and age, writing that “The greatest harm to experimental physiology was the negligence of researchers in the choice of experimental animals [which] they took…as they fell into their hands without attention to…species or age, and compared the results of experiments made in this manner as though they had compared animals of the same species and of the same age.” Legallois though that life depended on the impression of blood on the brain and the spinal cord, or on a principal resulting from this impression; death was therefore due to the extinction of that principle and might be only partial if the extinction were incomplete.

It had already been well accepted that locomotion and motility in general depend on the brain, which determines and regulates all animal functions. Legallois, however, concluded from his experiments that the principle of sensation and motility could only reside in the spinal cord, and that the brain is not the unique origin of nervous power. One of his most important achievements was the demonstration of the metameric organization of the spinal cord, by which each segment serves as a center of a specific region, coordinating its sensory and motor activity. “If instead of destroying spinal cord we divide it into its transverse sections, parts of the body corresponding to each spinal-cord segment conserve sensation and motility, but without harmony and each one independent of the others as if the sections were made across the whole body of the animal. In short, there are as many centers of sensation as there are spinal segments.” The brain thus regulates the movements of the body without supplying the immediate principle; this originates in the spinal cord. The brain acts on the spinal cord in the same way that the spinal cord acts on the muscles, the white matter of the brain being composed of filaments which end in the gray matter of the cord. This gray matter, the origin of the spinal nerves, is the seat of the principle of life.

The mechanics of respiration—those movements which make possible the entry of air into the lungs—depend immediately on the brain; since life is maintained by respiration, the life of the animal depends on the brain, through the medium of the spinal cord. Legallois then, in 1812, convincingly demonstrated that respiratory movements originate in a small area of the medulla oblongata near the occipital foramen and near the level of the origin of the vagus nerves. Indeed, if the cranium of a young rabbit is opened and the brain cut off in serial transverse slices, beginning at the stem, the whole of the cerebrum and of the cerebellum—as well as a part of medulla—can be removed; and respiration ceases suddently only when the lesion reaches the level of the vagus nerves. This effect is not due to the elimination of the vagi, since in an adult animal respiration goes on (although in a somewhat modified form) for a long time after their transsection.

Legallois was the first to draw attention to variations according to age in the respiratory reactions to the excitation of the central nervous system of animals of the same species. “Repetition of the same experiments on animals of various ages could throw light on many questions in physiology,” he wrote.

Legallois was cautious in drawing conclusions from his experiments. In dealing with complex phenomena he tried to isolate the elementary features and thus to determine the general laws of nature. His experiments were remarkable in the diversity and ingenuity of their design and arranged in a logical sequence. Legallois’s unshakable belief in the supreme importance of observations and well-performed experiments, together with his reserve in interpreting his data, indicate that he was a scientist of great stature.

Legallois died prematurely, about a year after his appointment to the great hospital and asylum of Bicêtre in the outskirts of Paris. He used to walk there from his home every day and in winter, after one such walk, contracted peripneumonia. Well aware of the physiological role of the blood, he refused the usual treatment of the time, bleeding, objecting that his inflammation was of “adynamic” nature, a theory to which some of his biographers believed that he fell victim. Legallois’s notion was, however, sound, although several decades had to pass before the disastrous practice of therapeutic bloodletting was abandoned.


I. Original Works. Legallois’s works were posthumously collected and edited by his son Eugéne as Oeuvres de J. J. C. Legallois avec des notes de M. Pariset, 2 vols. (Paris, 1824; 2nd ed., 1830). His most important and bestknown work, Expériences sur le principle de la vie, notamment sur celui des movements du coeur, et sur le siège de ce principe (Paris, 1812), was translated into English by N. Nancrede and J. Nancrede as Experiments on the Principle of Life and Particularly on the Principle of the Motion of the Heart, and on the Seat of This Principle (Philadelphia, 1813).

His other works include Le sang est-il identique dans tous les vaisseaux qu’il parcourt? (Paris, 1802), his M.D. diss.; Recherches chronologiques sur l’Hippocrate (Paris, 1804); several articles in the Dictionnaire des sciences medicales; and the posthumous Fragments d’um memoire sur le temps durant lequel les jeunes animaux peuvent etre, sans danger, prives de la respiration (Paris, 1834).

II. Secondary Literature. There is a biographical notice in Legallois’s Oeuvres, I, 1—11; and an anonymous “Notice biographique sur M. Legallois,” in Bulletin et mémoires de la Société de la Faculté de médecine de Paris,4 (1814-1815), 105-109. See also the article on Legallois in Dictionnaire des sciences médicales, biographie médicale, V (Paris, 1822), 565-566; G. Canguilhem, La formation du concept de reflexe aux XVII’ et XVIII’ siécles(Paris, 1955); E. Clark and C. D. O’Malley,The Human Brain and Spinal Cord (Berkeley-Los Angeles, 1968); A. Dechambre, in Dictionnaire encyclopédique des sciences médicales, 2nd ser., II (Paris, 1876), 138-139; P.Huard, “César Legallois (1770-1814) decouvre en 1811 le principe de la resuscitation,” in Histoire de la médecine,4 (1954), 23-25; M. Neuburger, Die historische Entwicklung der experimentellen Gehirnund Rückenmarksphysiologie von Flourens (stuttgard, 1897); and J. Sourry, Systéme nerveux central. Structure et functions (Paris, 1899).

The reports of the National Institute of France on Expériences sur le principle de la vie and on Legallois’s other experiments are trans, in A. P. W. Philip, An Experimental Inquiry Into the Laws on the vital Functions (London, 1817; Philadelphia, 1818).

Vladislav Kruta

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