MORAT, JEAN-PIERRE

(b. St.-Sorlin, Saône-et-Loire, France, 18 April 1846; d. La Roche-Vineuse, near St.-Sorlin, 25 July 1920)

physiology.

Morat contributed to physiological knowledge primarily by his studies of what is now called the autonomic nervous system; in particular, he and Albert Dastre showed in 1880 that stimulation of the cervical portion of the sympathetic nerve led to vasodilation in the gums and hard palate of the dog. His subsequent research emphasized the general significance of vasodilator nerves in the regulation of organic function.

Morat studied at Lyons in the early 1870’s and then in Paris, where he worked in Claude Bernard’s laboratory at the Museum of Natural History and in 1873 received his medical degree from the Faculty of Medicine.

From 1873 to 1876 Morat served as the chef des travaux anatomiques for the medical school at Lyons. A year after the founding of a new Faculty of Medicine at Lille in 1875, he became the chargé de cours for physiology and assistant professor of the subject in 1878. He returned to Lyons in 1882 as professor of physiology at the Faculty of Medicine and Pharmacy, which had been established in 1877. He became an associate member of the Société de Biologie in 1906 and a correspondent of the medical and surgical section of the Academy of Sciences in 1916.

In 1899 Morat received the Academy’s Lacaze Prize for his research career, which was dominated especially by the ideas and techniques of Bichat, Bernard, and Chauveau. In 1877 he had won the Academy’s Montyon Prize in experimental physiology for his first significant research, which concerned muscle physiology.¹

This work was performed with J. J. H. Toussaint in Chauveau’s laboratory and depended on both the graphical recording techniques developed by Chauveau and Marey and the use of Chauveau’s unipolar electrode. It clarified the analogy which had been drawn between induced tetanus and the voluntary contraction of skeletal muscle by showing that the two were comparable only when the tremors composing tetanus were perfectly fused.

Morat and his later, more renowned, collaborator, Dastre, began their joint study of the vasodilator nerves (1876–1882) in Chauveau’s laboratory. They were among the first to employ simultaneous graphical recordings of arterial and venous pressures to study vasomotor action. Chauveau and Marey had previ-ously used a similar method to study other aspects of circulation.

At the beginning of their study of the vasomotor nerves, Morat and Dastre assumed the inverse of what they are best known for having discovered: the vasodilatory effect of excitation of the cervical portion of the sympathetic nerve. In their attempt (1878) to resolve the question of whether the sciatic nerve had vasodilator properties, they used the cervical sympa-thetic nerve as an exemplar of a vasoconstrictor. They argued that since excitation of the sciatic had the same effect on vascular pressures as excitation of the cervical sympathetic, then the sciatic, like the cervical sympathetic, must be a vasoconstrictor.

Two years later, however, Morat and Dastre announced that the cervical sympathetic was a vasodilator.² The reason for the change is unclear; but it seems to have resulted from interpreting the recent studies of other researchers in the light of views they already held, which were based on those of Bernard. In Bernard’s view, vasodilation resulted from nervous inhibition or paralysis of vasocon-strictor nerves. On this basis Dastre and Morat had supposed that if vasodilator nerves were present, they were most likely to be found related to ganglia (where the inhibitory action would be localized), especially those of the sympathetic. At about the same time that they were studying the sciatic nerve, work by others had shown that branches of the submaxillary nerve caused dilation in vessels of certain parts of the face and that the submaxillary nerve’s dilator fibers did not originate in the brain. Their expectation that vasodilators were related to ganglia probably led Dastre and Morat to suppose that the submaxillary dilator fibers arose at the corvical ganglia of the sympathetic and, hence, to test the cervical sympathetic to see whether it caused dilation in the specified regions of the face, which it did.

Morat’s research frequently returned to topics related to vasodilation or to other functions mediated by the sympathetic system. For example, he collab-orated with Maurice Doyon in demonstrating (1891) that sympathetic nerve fibers have an effect opposite to that of the ciliary nerve: they accommodate the lens of the eye for nearby objects.

In their study of the consumption of sugar by resting muscle (1892), Morat and H. Dufourt used Bernard’s chemical test for blood sugar to treat a problem that Bernard’s work had suggested and that Chauveau had explicitly raised: the role of glycogen in the various organs of the body. This work led to a study of nervous control over liver glycogenesis (1894), which showed that liver glycolysis can be stimulated without changing the flow of blood through hepatic vessels and, thus, independently of its vasomotor nerves.

In Morat’s later studies of vasodilation he rejected Bichat’s view that had dominated his early thought about the sympathetic system: that the sympathetic system was independent of the cerebrospinal system and was the sole regulator of visceral organ function. In 1894 Morat expressed the view that vasodilation was localized neither in the spinal nor in the sympa-thetic trunk but was a property of certain nervous elements which compose both these trunks.

In rejecting Bichat’s distinction Morat made no ref-erence to the histological results which had led Gaskell to a similar conclusion a decade earlier. Rather, Morat had come to regard metabolic and functional behaviors as concurrent activities, elicited at the same time by the same fiber. For this reason there was no longer any motive for ascribing all “organic” vasomotor functions to a distinct nervous structure, the sympathetic trunk.

Morat’s last significant research, performed with M. Petzetakis just before the beginning of World War I, showed that cardiac fibrillation can result from a disequilibration between cardiac excitor and inhibitor nerves, and that the rhythms of auricles and ventricles are mutually related but not in a totally dependent fashion.

NOTES

1. The report of the commission awarding the Lacaze Prize appears in Comptes rendus de l’Académie des sciences, 129 (1899), 1140–1144. The Montyon commission report is ibid., 84 (1877), 848–851.

2. Dastre and Morat claimed that this result of work begun in 1876 was first announced to the Société de Biologie in 1878; but there are no citations to Morat in the Society’s 1878 Mémoires et comptes rendus, and the note he alluded to seems to be one of a series submitted in 1880 and published in 1881. The error may have been part of an effort to avoid a priority dispute with Jolyet and Laffont, whose study of dilation in the facial region, published in 1878, may in fact have led immediately to the finding by Dastre and Morat.

BIBLIOGRAPHY

I. Original Works. Morat published about 75 scien-tific papers, more than half of which were written in collab-oration with other physiologists. Papers published prior to 1900 are indexed in the Royal Society’s Catalogue of Scientific Papers, X, 843–844; XII, 184, 519; XVII, 342–343; and XVIII, 278.

Among the most important are “Variations de l’état électrique des muscles dans différents modes de contrac-tion …,” in Archives de physiologie normale, 2nd ser., 4 (1877), 156–182, written with H. Toussaint; “Sur l’expé-rience du grand sympathique cervical,” in Comptes ren-dus… de l’Académie des sciences, 91 (1880), 393–395, written with A. Dastre; “Sur la fonction vasodilatatrice du nerf grand sympathique,” in Archives de physiologie, 9 (1882), 177–236, 337–382, written with A. Dastre; “Le grand sympathique nerf de l’accommodation pour la vision des objets éloignés,” in Comptes rendus … de l’Académie des sciences, 112 (1891), 1327–1329, written with M. Doyon; “Les fonctions vaso-motrices des racines postérieures,” in Archives de physiologie, 5th ser., 4 (1892), 689–698; “Nerfs et centres inhibiteurs,” ibid., 6 (1894), 7–18; “Les nerfs glyco-sécréteurs,” ibid., 371–380, written with E. Dufort; and “Le système nerveux et la nutrition. Les nerfs thermiques. [Les nerfs trophiques.],” in Revue scientifique, 4th ser., 4 (1895), 487–495; 5 (1896), 193–199, 234–241.

In addition to papers indexed in the Royal Society’s Catalogue of Scientific Papers, Morat published the fol-lowing: “Réserve adipeuse de nature hivernale dans les ganglions spinaux de la grenouille,” in Mémoires de la Société de biologie, 53 (1901) 473–474; “La réforme des études médicales,” in Revue scientifique, 5th ser., 5 (1906), 524–526; “Les racines du système nerveux: Le mot et la chose,” in Archives Internationales de physiologie …, 8 (1909), 75–103; “Les variations de la formule sanguine chez les morphinomanes et les héroïnomanes au cours de désintoxication rapide par la méthode de Sollier,” in Mémories de la Société de biologie, 66 (1909), 1025–1027, written with Chartier; and three articles written with M. Petzetakis: “Production de la fibrillation des oreillettes par voie nerveuse, au moyen de l’excitation du pneumo-gastrique,” ibid., 77 (1914), 222–224; “Fibrillation auricu-laire et ventriculaire produite par voie nerveuse,” ibid., 377–379; and “Production expérimentale d’extrasystoles ventriculaires retrogrades, et de rythme inverse, par inver-sion de la conduction des excitations dans le coeur,” in Comptes rendus … de l’Académie des sciences, 163 (1916), 969–971.

Morat also published with A. Dastre a book-length account of iheir study of the vasomotor system: Recherches expérimentales sur le système nerveux vasomoteur (Paris, 1884). With Maurice Doyon he wrote Traité de physiologies, 5 vols. (Paris, 1899–1918). Vol. II, Morat’s treatment of the nervous system, was translated into English and pub-lished under the title Physiology of the Nervous System (London, 1906).

II. Secondary Literature. The longest published account which I have been able to locate of Morat’s life is a paragraph in Biographisches Lexikon der hervorragen-den Ärzte, 1800–1930, II (Munich, 1962), 1065.

Background for Morat’s work on vasodilation is in Donal Sheehan, “Discovery of the Autonomic Nervous System,” in Archives of Neurology and Psychiatry, 35 (1936), 1081–1115, esp. 1102–1105; and E. A. Schafer, ed., Textbook of Physiology, II (London, 1898), 71, 130–136, 618, 626, 659–661.

Michael Gross