Etienne-Jules Marey: the medical innovation

Claude Debru
Professeur à l'école normale supérieure

Décembre 2004

On December 17th, 1912, at the Académie de Médecine, Charles François-Franck pronounced the following words in praise of Marey: "Marey (Etienne-Jules), born in Beaune (Côte d’Or) on March 5th, 1830, died in Paris on May 15th, 1904, after a fifty-year-long scientific career. He was a Professor at the Collège de France, a member and former President of the Académie des Sciences and of the Société de Biologie; he joined the Académie de Médecine in 1872 and presided over it in 1900. I have been called on today to talk about this man, who was so eminent on account of his functions and responsibilities, and even more so on account of what he did in Physiology. However difficult a task this may be, I felt it was my duty to accept it, out of respect for the memory of the man who once was my master, and out of deference to the Académie that entrusted me with it". Through his work, Marey, a century after his death, appears as an exceptionally inventive pioneer. Unfortunately, it is impossible to talk about the totality of his work within the time limits that I have been given. I will therefore merely present those aspects that are related to medicine, and comment on the singularity of this work that bridges medicine, science, technology and art.

Marey studied medicine and may be said to have received its imprint. He came in first at the entrance examination for the internship in 1854 and was assigned to Professor Joseph-Simon Beau’s service in Cochin hospital. He published seven articles, of which three appeared in the Comptes rendus de l’Académie des Sciences and one in the Comptes rendus de la Société de Biologie; he then defended his medical doctorate on March 4th, 1859. This thesis, Research on blood circulation in the physiological state and in diseases , is a beautifully written, strikingly clear classic work. In it, the 29-year-old candidate already shows himself to be a master, as his chief examiner Jules Gavarret wrote. Marey was bent on following the path of Physiology. He wrote: "Physiology only began to play its important role in medicine after it grasped the innermost functions of organic life... Today, the benefits of physiology have to be extended to all the branches of medicine". The young scientist always kept in mind medical practice, which he wanted to render easier thanks to new, better-adapted instruments. He did physiological reseach precisely to achieve this goal. His judgement was both sound and harsh, his preoccupations both philosophical and experimental. "In the beginning, every science is cluttered with hypotheses; any newly discovered fact is attributed its own cause, power or property. Bichat exemplified for us that propensity for using words that in fact explain nothing". But if he judged harshly, he was also endowed with an inventive mind, which allowed him to develop original new physiological instruments made to help understand the subtleties of physiology as the science of movement. Marey, who somehow reminds one of Da Vinci in his analysis of animal movement, or of Harvey whose conclusions on the movements of the heart he confirmed, is a very good illustration of a remark that Henry Sigerist, a historian of medicine, made: the physician of the baroque age "does not see the muscle, but its contraction and the effects it produces. This is how anatomia animata, or physiology, was born. What this science studies is movement. It opens doors on limitless horizons. Every physiological problem brings us back to the sources of life and reveals infinity". Marey was seized by the passionate desire to understand the conditions, the mechanisms and the paces of vital movements. In his thesis, he presented original research work on the elasticity and contractility of blood vessels. As a physicist, he reasoned upon artificial models, namely elastic tubes in which he intermittently injected a liquid – thus imitating the intermittent character of the blood influx in the vessels. He added two measuring apparatuses: a manometer built by himself to indicate average pressure, and a sphygmograph, an improved version of the apparatus built by Karl Vierordt in Tübingen (Germany) to record the pulse. The sphygmograph measured the shape of the stroke output at more or less distant points. Three manometers and three sphygmographs were placed at various distances along the tube so that, as Marey explained, "the graphic indications of the movement are recorded in several places at the same time, which allows one to see, in one glance only, what on each curve corresponds to one given moment". Marey, young though he was, participated in the European race (with physiologists such as Karl Ludwig, Wilhelm Volkmann or Karl Vierordt) to understand blood circulation; he even took the lead thanks to his inventiveness. He was well aware that his problem was not only to measure or to record but to record without perturbing the system. It was therefore necessary to capture even the slightest pulsations of life, which he did thanks to the new dialogue between physics and clinical medicine. Marey came to understand better the active role of elasticity, a physical property, in blood circulation. He understood even better that of contractility, the vital property that helps regulate circulation in the vessels (notably by using himself as the subject of various experiments). Contractility modifies elasticity, but the latter maintains its role in blood flow. The point of his studies was to explain how the two conditions combine. Naturally, Claude Bernard’s discoveries on the vasomotor action of the sympathetic nervous system were turned to good account. Marey would subsequently never stop exploring through measurement the various phenomena of blood pressure, and defining the most appropriate ways to measure them. In 1878 he set down the rules we know today, demonstrating why both the minimum and the maximum have to be established, and leaving it to his colleagues to design the corresponding apparatuses.

Marey soon produced a physical and anatomical explanation of the dicrotic pulse. He had observed the double-beating pulse in the service of his master Joseph-Simon Beau, who had discovered that dicrotism does not affect the inferior limbs. As an independent, self-assured mind, Marey in his thesis did not always agree with Beau’s views. He did not agree either with those of Jean-Baptiste Auguste Chauveau, Chef des travaux d’anatomie et de physiologie (head of anatomy and physiology) at the Ecole impériale vétérinaire in Lyon, who studied the arterial pulse of horses. When confronted with vitalist criticisms, Marey showed a flawless logic and a biting irony that recalled those of Louis Pasteur. In 1860, Marey submitted to the Société de Biologie his Investigations on the pulse via the sphygmograph, a recording apparatus , the latest in a series of devices created to record the pulse. The previous one, Vierordt’s, indicated only the number of beats, their regularity and their amplitude. Marey’s sphygmograph was much lighter, hence portable; it was an armband placed on the forearm; the pressure it exerted on the artery could be modulated; the device was quite sensitive, and indicated not only the variations in the pulse, but also blood pressure: the shape of the beats only had to be compared with the shape recorded when the sphygmograph was attached to an artificial system (an elastic tube submitted to various pressures). Marey concluded that the shape of the pulse "is usually a good way to appreciate (...) blood pressure". Marey would later come back to the use of the sphygmograph to measure blood pressure directly – which is an erroneous use of the device. The sphygmograph, however, illustrates how much physical model and physiological research echo and explain each other. Physiology is physics endowed with vital properties, the conditions of which should be sought, according to Marey’s positivistic philosophy, without trying to understand the inaccessible causes. And how can the vital movements be understood without resorting to mechanical models? This is why he used elastic tubes and sphygmographs.

But Marey went further. Thanks to Chauveau, he moved from vascular circulation to cardiac motricity. Although Marey criticized Chauveau in his thesis, the two men, who were roughly the same age, admired each other, and they collaborated actively and fruitfully. The Dutch physiologist Frans Cornelius Donders, who was an admirer of Marey’s, was instrumental to the meeting of the two scientists, which took place at the Ecole vétérinaire in Alfort in 1859. From 1855 to 1857, Chauveau had studied the movements and the sounds of horses’ hearts. The graphic method used by Marey provided Chauveau with new instruments for studying the heart’s movements. The two scientists therefore initiated an intense collaboration in cardiography and published a series of remarkable articles between 1861 and 1864, among them, Cardiographic devices and experiments. A new demonstration of the mechanism of the heart’s movements by the use of recording apparatuses with continuous indications , published in the Mémoires de l’Académie de Médecine in 1863. In this article, Chauveau and Marey described the cardiograph, made with sphygmographs that record the movements of the atrium, the ventricle and the heart beat. The three sphygmographs were connected to a recording device. A particularly important innovation was catheterism, or the introduction of probes into the atrium and the right ventricle through the jugular vein, the third one being inserted in the chest where the heartbeat is clearest; the purpose of the probes was to relay movements. This apparatus was used on horses. The simultaneous graphing of the three types of movement as curves allowed the scientists to answer important questions about the cycle of cardiac movements. Cardiac pulsation corresponds to ventricular contraction, and not to dilatation, as Beau thought (he believed that the heart beat when it relaxed). The ensuing controversy between master and former student occupied the Académie de Médecine for about a year, from 1863 to 1864. Chauveau and Marey did not really participate in the debate, which mainly took place between Beau and Bouillaud. The two passionate orators engaged in violent arguments – now outmoded in the Académies. Jules Gavarret, who had introduced Marey and Chauveau’s thesis with great enthusiasm on April 21, 1863, ended the controversy on July 12, 1864. The physiological cardiography of Chauveau and Marey was an illustration and a continuation of Harvey’s theory of the movements of the heart.

From 1863 on, Marey, fortified by the success encountered with his friend Chauveau, started building artificial hearts and circulatory apparatuses. His book Medical physiology of blood circulation based on the graphical study of the heart’s movements and of the arterial pulse with application to the diseases of the circulatory system , published in 1863, aimed precisely at "studying the various forms of movement in vital functions" (p. 11). Indeed, according to Marey, "it would be a real hindrance for medecine not to take advantage of these discoveries", referring to those made with the recording apparatuses that provide continuous indications (p. 13). Movement becomes "absolutely clear" to the physicist who records and analyses it. But analysis is not enough to establish the fact that some physiological mechanisms do take place. For this, a "synthetic counter-test" is necessary, and one has to build not only recording, but also producing apparatuses. Marey therefore imagined a device that imitated the left side of the heart, with the ventricular contraction produced by a hand-controlled pneumatic system (p. 42). This "synthetic reproduction" of the heart’s movement aimed at "making us understand the cause of the exterior signs that reveal blood circulation in a healthy or unhealthy man." It thus becomes possible to associate the knowledge of what happens in the heart with the knowledge of its exterior manifestations, which allows one to infer, from exterior signs only, the functioning of the heart, be it normal or pathological. Marey showed extraordinary virtuosity when he created these apparatuses, modifying them and refining them constantly. He mastered physiology as if it were a children’s game. In his book he provided an impressive diagram of arterial circulation (p. 164), just as he had done for the left side of the heart. Sounds, murmurs, constrictions no longer have any secrets. Physiology and pathology are accounted for thanks to simulation.

Although he was involved in research work on motricity in general, and worked at developing the graphic method and later chronophotography applied to all sorts of problems, Marey never stopped progressing in his first subject of interest. The graphic method in the experimental sciences and more specifically in physiology and medicine , published in 1878, presents countless methods, discoveries and applications, but also Marey’s work on circulation, the heart and blood pressure. His most important book, Blood circulation in the physiological state and in diseases , published in 1881, was a continuation and an amplification of his 1863 Medical physiology of blood circulation . Modifications of the existing apparatuses were introduced for the pulse and the sounds of the heart to be better reproduced. But the most remarkable feature is probably the invention of an artificial system of double circulation, the purpose of which was to "reproduce the form of the heart beat and of its variations, according to the arterial or venous tension, to the strength of the heart, the amplitude of its movements, the state of its orifices or of its valvules" (p. 710). "When I built this apparatus, after countless trials and errors, I did not give in to the childish desire of building an automaton; I considered that our knowledge of circulation would be all the clearer for this experimental control. I have not been disappointed in my expectations " (p. 712). But that was not all. In his book Movement, published in 1894, Marey applied chronophotography to the movements of the heart, using for this purpose the heart of a turtle removed from the animal and placed in artificial circulation; "an energetic circulation is established; it lasts from six to ten hours, and even longer, according to the season" (p. 279). The images thus obtained, at a rate of ten per second, enabled one to describe each phase and to deduce its duration. The cardiographic method had been indirect. The chronophotographic one was direct but, unfortunately, it was also intermittent. To see better, Marey used a procedure already in use to photograph movement: he painted the turtle’s heart white, which allowed him, using lights and shadows, to have a better view of how the heart’s parts change shapes. The last chapter of his book was devoted to microscopic chronophotography, which would later become microcinema. Physiology, technology and art intermingle. An almost limitless field is opened.

Marey lived in a time of pioneers. He was first among the pioneers and gave rise to many controversies. Beau’s attacks on his theory of the movements of the heart, which took place at the Académie de Médecine in 1863-64, were not unique. In 1878, Colin did not show any more respect for Marey and his graphic method than he did for Pasteur.

In 1883 and 1884, the leap of men and the flight of birds antagonised Marey and Marc-Antoine Giraud-Teulon. The research on the flight of birds led straight to the development of planes via the artificial bird tested in Marey’s laboratory.

One can understand why Marey was compared to Da Vinci. Their inventiveness and their visionary character made them scientists, technicians and artists. Marey’s graphics have influenced some futuristic schools of modern art. Marey was surprisingly creative. He developed to the utmost man’s ability to analyse visually and spatio-temporally. As he scrutinized what was real, he also saw what was possible, and understood how close the one was to the other. Analysing and developing what is real makes what is possible come true. Marey was a great visualizer, but he was also a great visionary who still inspires us today.

Première publication : Bull. Acad. Natle. Méd., 2004, 188, n° 8, 1413-1421. Nous remercions le Professeur Jacques Louis Binet, Secrétaire perpétuel de l’Académie nationale de médecine, ainsi que M. Debru, d’avoir autorisé la reproduction de cette communication sur le site de la BIUM. Tous droits réservés.

Translation by Karine Debbasch, Université René Descartes - Paris 5