Dutrochet, René-Joachim-Henri

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Dutrochet, René-Joachim-Henri

(b. Néon, France, 14 November 1776; d. Paris, France, 4 February 1847)

animal and plant physiology, embryology, physics, phonetics.

Dutrochet was born at a seignorial mansion near Poitiers; he was the eldest son of wealthy and noble parents. His early childhood was spoiled by club-foot, which—after unsuccessful medical consultations—was completely healed by a renowned healer, who was also a hangman.

The Revolution brought expropriation of family property after his father emigrated; Dutrochet was therefore forced to rely on his own resources. He volunteered for the navy in 1799, then deserted and joined his brothers in the last Royalist units. Following 18 Brumaire, which with the accession of Bonaparte to the Consulate brought an end to the Royalist resistance and a general amnesty, Dutrochet spent two peaceful years with his family. He was, however, dissatisfied with such an empty and useless life, so in 1802, at the age of twenty-six, he went to Paris to study medicine. Graduating in 1806, he qualified as a military medical officer in 1808 and was sent to Spain. With great devotion and sacrifice and lacking adequate material means, he dealt with a severe outbreak of typhoid in Burgos. He believed that he had found his true vocation until, having contracted the disease himself, he was so weakened that he had to return to France for a long convalescence. He joined his mother in a country house near Château-Renault in Touraine, where he lived in seclusion from society and decided, at the age of thirty-four, to abandon medical practice and devote all his efforts to natural science. In 1819 he was elected corresponding member of the Académie des Sciences; in 1831 he was elected to full membership. After his mother’s death he lived in Paris during the winter months and returned in summer to his country residence. In 1845 he suffered a blow on the head which, after a long illness marked by severe headaches, led to his death.

Dutrochet’s first scientific interest, which he pursued even before he finished his medical studies, was phonetics. In 1806 he repeated Ferrein’s experiments on the larynx and tried to establish the relationship between pitch and tension of the vocal cords under different loads—these experiments, however, have been overshadowed by his subsequent studies and are almost forgotten.

Dutrochet’s investigations into the development of birds, reptiles, batrachians, and mammals, published in 1814, are more important. In them he paid special attention to the hitherto neglected early stages of development of the egg within the ovary, to its detachment, and to the fetal membranes. (One of them, the external yolk membrane of the bird’s egg, whose fibers are continuous with the chalazae, is called “Dutrochet’s membrane.”) He also made several original observations on fetal development, but it was his demonstration of the analogy of fetal envelopes in ovipara and vivipara that suggested a unity of the main features in the development of animals and proved extremely valuable for further studies.

The principal field of Dutrochet’s studies was plant physiology, although he also studied that of animals. He further explored the areas that were common to both, especially the exchange of gases between the atmosphere and plant or animal tissues—the key to the life processes. He asserted that respiration is of the same nature in both plants and animals. Active breathing in animals had been evident to observers since very early times; in plants, however, the existence of respiration was brought to light much later. In 1832 Dutrochet showed that the minute openings on the surface of leaves (the stomata) communicate with lacunae in deeper tissue. He further demonstrated that only the green parts of the plant can absorb carbon dioxide and thus transform light energy into chemical energy that can then serve to accomplish all kinds of syntheses.

In his studies of excitability and motility Dutrochet tried to demonstrate that these widespread phenomena are essentially the same in both plants and animals, since they utilize the same organs and mechanisms. In contrast to the then current explanation of these phenomena—which was based on Naturphilosophie and depended on intervention of the “vital force”—he stressed anatomical and mechanical arguments. For example, he emphasized the importance to plant motility of the turgor of the hinge cells, the passage of water out of the cells on one side into the intercellular spaces, and so forth.

Dutrochet’s research on the phenomena of osmosis and diffusion (or endosmosis and exosmosis, as he not very aptly called them) and their applications to the study of previously unexplained vital phenomena attracted general attention. His chief observation was that certain organic membranes allow the passage of water but stop the molecules dissolved in it, so that between two solutions of different concentration, separated by such a membrane, water passes from the less concentrated to the more concentrated, even against gravity. Although the conditions of Dutrochet’s experiments were rather simple and did not allow of great accuracy, he made the first important steps toward the study of osmosis and diffusion. He constructed an osmometer for measurements of osmotic pressure and pointed to such pressure as the possible cause of circulation and rise of sap in plants, absorption of nutrients in plants and animals. His experiments were developed by many of his younger colleagues, and his ideas played an important role in their thinking, for example, in Carl Ludwig’s hypothesis of the formation of urine in the kidneys (1842).

Among Dutrochet’s other discoveries, it may be noted that in 1831 he demonstrated that mushrooms are in fact the fruiting bodies of the mycelium; they had been previously considered to be a particular genus (called byssus). He was also the first (1840) to detect, by a thermoelectric technique, the production of heat in an individual plant and in an insect muscle during activity.

Dutrochet is also considered to be the founder of the cell theory; but his ideas are actually more in the nature of shrewd, intuitive anticipations rather than conclusions based on his own microscopic observations. His illustrations are not convincing and it seems that, at least in some cases, Dutrochet’s “globules” (cells) were optical artifacts produced by poor lenses and bad illumination. Although he expressed his ideas in language similar to that of the cell theory, these ideas and the observations upon which they were based were not equivalent to it. Dutrochet himself made no claim to priority when Schwann’s book was published in 1839.

Dutrochet’s observations and experiments were often unsatisfactory; his means were largely inadequate. He was often mistaken in his conclusions or made false parallels between plants and animals. His importance lies more in the systematic endeavor to demonstrate that vital phenomena can be explained on the basis of physics and chemistry, that living organisms use physical and chemical forces, and that there is no reason to suppose the existence of some intervention of a “vital force.” He strove to generalize and to show the unity of basic processes in all living things, both plant and animal. His experimental studies and observations led him to the conclusion that there is only one physiology, only one general science of the function of living bodies. His attempt to apply physicochemical forces and phenomena in explanation of physiological processes overcame that mysticism which had been introduced into physiology by teleologically minded physiologists.

A convinced antivitalist, Dutrochet developed a unitary conception of a nature—animate and inanimate, organic and inorganic, all subject to the laws of physics and chemistry. For this reason he had a great influence on his younger colleagues; for example, in 1841 du Bois-Reymond wrote, “I am gradually returning to Dutrochet’s view. The more one advances in the knowledge of physiology, the more one will have reason for ceasing to believe that the phenomena of life are essentially different from physical phenomena.” Dutrochet’s work was also greatly appreciated by the distinguished plant physiologist Julius Sachs.

BIBLIOGRAPHY

I. Original Works. Dutrochet’s writings include Essai sur une nouvelle théorie de la voix, avec l’exposé des divers systèmes qui ont paru jusqu’à ce jour sur cet objet (Paris, 1806); Mémoire sur une nouvelle théorie de la voix (Paris, 1809); Mémoire sur une nouvelle théorie de I’harmonie dans lequel on démontre l’existence de trois modes nouveaux, qui faisaient partie du système musical des Grecs (Paris, 1810); Recherches anatomiques et physiologiques sur la structure intime des animaux et végétaux (Paris, 1824); L’agent immédiat du mouvement vital dévoilé dans sa nature et dans son mode d’action chez les végétaux et animaux (LondonParis, 1826); and Nouvelles recherches sur l’endosmose et l’exosmose, suivies de l’application expérimentale de ces actions physiques à la solution du problème de l’irritabilité végétale, et à la détermination de la cause de l’ascension des tiges et de la descente des racines (Paris, 1828). Further observations on the osmotic phenomena were published as “Nouvelles observations sur l’endosmose et l’exosmose, et sur la cause de ce double phénomène,” in Annales de chimie et de physique, 35 (1827), 393–400; “Nouvelles recherches sur l’endosmose et l’exosmose,” ibid, 37 (1828), 191–201; “Recherches sur l’endosmose et sur la cause physique de ce phénon.ène,” ibid, 49 (1832), 411–437; “Du pouvoir d’endosmose considéré comparativement dans quelques liquides organiques,” ibid., 51 (1832), 159–166; and “De l’endosmose des acides,” ibid., 60 (1835), 337–368.

II. Secondary Literature. On Dutrochet and his work, see Notice analytique sur les travaux de M. Henri Dutrochet (Paris, 1832); A. Brongniart, Notice sur Henri Dutrochet (Paris, 1852); J. J. Coste, Éloge historique de Henri Dutrochet (Paris, 1866); Gazette médicale de Paris, no. 11 (1866); and I, Geoflroy Saint-Hilatre, in Biographie universelle, XII (Paris, 1855). For Dutroehet’s place in the history of the cell theory see A. R. Rich, “The Place of R. J. H. Dutrochet in the Development of the Cell Theory,” in Bulletin of the Johns Hopkins Hospital, 39 (1926), 330–365; F. K. Studnička, “Aus der Vorgeschichte der Zellentheorie. H. Milne Edwards, H. Dutrochet, F. Raspail, J. E. Purkinje,”in Anatomischer Anzeiger, 73 (1931),390–416; and J. W. Wilson, “Dutrochet and the Cell Theoty,” in Isis, 37 (1947), 14–21. His work in plant physiology is discussed by J. Sachs in Geschichte der Botanik (Munich, 1875), English trans. by H. E. Garney (Oxford, 1890).

Vladislav Kruta