PEYSSONNEL, JEAN ANDRé

(b. Marseilles, France, 19 June 1694; d. Guadeloupe, 24 December 1759)

botany, zoology.

The eighth child of a physician at the Hotel-Dieu in Marseilles, Peyssonel visited the Anatilles at the age of fifteen and Egypt three years later. He studied medicine at the University of Aix, where he defended his dissertation before a jury headed by his father. He began practice in Marseilles, which in 1720 suffered a severe epidemic of plague; Peyssonnel’s effors on behalf of the stricken were rewarded by a royal pension. During his year in Marseilles, Peyssonnel and some friends founded an academy devoted to belles lettres, in the tradition of the“ancient academy” of Marseilles.

A naturalist by inclination, Peyssonnel was interested in marine natural history. He observed the Mediterranean currents and studied corals, confirming the “flowering” established twenty years earlier by Count Luigi Marsigli. How the plant produced the red, stony portion, however, remained a mystery. Peyssonnel informed the president of the Paris Academy of Sciences, the Abbé Jean-Paul Bignon, of the progress of his research. In 1723 he became a correspondent of the Academy, to which he presented a paper on coral, which he then considered to be a flowering plant, in 1724.

Sent by the king to the Barbary Coast “to make discoveries in natural history” and to visit the country around Tunis and Algiers, Peyssonnel described his travels in letters to Bignon and in 1726 sent him two papers concerning his research on madrepores and other corals. The essence of his findings was that corals are not plants, but animals. The so-called flowers retract on contact with air but reappear when returned to the sea. It is animal matter, soft and milky, that covers the organism’s stony parts. Further, Peyssonnel believed that “insects,” such as the sea anemone, are also corals and madrepores. Peyssonnel’s text, transmitted by Bignon to Reaumur, was read at the Academy on 8 and 28 June and 3 July 1726, Reaumur did not mention the author’s name for fear of subjecting a distinguished person to ridicule: the idea seemed unacceptable to everyone, as Peyssonnel was informed in letters from Reaumur and Bernard de Jussieu.

Undaunted, Peyssonnel continued his studies in marine natural history. His pamphlet of 1726, Memoire sur les courans de la Mediterranee was the first work written on the Mediterranean currents. Distributed by the municipal magistrates of Marseilles to ship captains, it stimulated them to communicate their own observations.

In 1727 Peyssonnel departed for Guadeloupe as“royal botanist to the American islands” He spent the rest of his life on that island, where he married and fathered a son and several daughters. Although prevented by administrative difficulties from mining the sulfur of the Grande Soufriere volcano, which he had explored, he continued his research on marine life. His results provided him with complete confirmation of his earlier assertions, a fact he communicated in a letter of 1733 to Antoine de Jussieu.

In 1740 Trembley discovered the green hydra that Reaumur called a polyp, and the analogy with “marine plants” was cited. Guettard and Bernard de Jussieu confirmed, on the French coast, Peyssonnel’s findings, and Reaumur admitted his own error (Memoires pour servir a l’histoire naturelle des insectes, VI[1742], preface). Although he regained the exteem of the Academy, of which he was a corresponding member, it was to the Royal Society of London that Peysonnel sent a manuscript on coral(in French). A resume of it was presented to the Society on 7 May 1752 by W.Watson, who stressed the high quality of Peysonnel’s work (Philosophical Transactions[1753]) In 1756 Peyssonnel published in London a translation of Watson’s article, supplemented by various writings on a plan to establish an annual prize at the Academy of Marseilles, to be awarded for the best paper on a subject in marine natural history. From 1756 until his death in 1759 he presented ten further articles recording his scientific observations to the Royal Society.

BIBLIOGRAPHY

I. Original Works. Peyssonnel’s published works are La contagion de la peste expliquee et les moyens de s’en preserver, par le S***, Docteur en Medecine (Marseilles, 1723); Memoire sur les courans de la Mediterraneé (Marseilles, 1726), 600 copies of which were printed at the expense of the Chambre de Commerce de Marseille, repr. in the 1756 collection under the title“Essai de physique ou conjectures fondees sur quelques observations qui peuvent conduire a la connaissance et a l’explication des courans de la mer Méditerranée”, and Traduction d’un article des Transactions Philosophiques sur le Corail—Project propose a l’Academie de Marseille pour l’establishment d’un Prix... et response de l’Academie. Diverses observations sur les courants de la Mer, faits en diffents endroits (London, 1756).

II. Secondary Literature. For the coral controversy see Rergistre de l’Academie des sciences8 and 28 June and 3 July 1725;“Sur le corail,” in Histoire de l’Academie royale des sciences (1727), 37-39; Reaumur,” Observations sur la formation du corail et des autres productions appelees plantes pierreuses,” in Memoires de l’Academie royale des sciences (1727), 269-281; Bernard de Jussieu,“Examen de quelques productions marines qui ont etemises au nombre des plantes et qui sontl’ouvrage d’une Flourens, “Analyse d’un ouvrage manuscrit intitule Traite du Corail,” Annalels Sc. nat. Zoologie, ser. 2, 9 (1838), 334; and “Analyse d’un ouvrage manuscrit intitule Traite du Corail par le Sieur de Peyssonnel,” in Journal des Savants (Feb. 1838). See also Dureau de la Malle, Peyssonnel, and Desfontaines, Voyages dans les Regences de Tunis et d’Alger (Paris, 1838); Alfred Lacroix, “Notice historique sur les cinq de Jussieu,” in Mémoires de l’Institut,63 (1941), 24; and Noel Duval, “La solution d’une enigme: les Voyageurs Peyssonnel et Gimenez a Sbeitla en 1724,” in Bull. Soc. Nat. Antiquaires France (2 June 1965).

Lucien Plantefol