(b. Paris, France, 21 October 1866; d. Nancy, France, 7 January 1951)
zoology, general biology.
The son of a postal employee, Cuénot was a brilliant student at the Collège Chaptal. After receiving the baccalauréat ès sciences, he enrolled in 1883 at the Faculty of Sciences of the Sorbonne, where the courses given by Lacaze-Duthiers led him toward zoology. He placed first on the licence examination in 1885 and became docteur ès sciences naturelles at twenty-one with a thesis on Asteriidae (1887). Cuénot was appointed préparateur in comparative anatomy and physiology at the Faculty of Sciences in Paris in 1888 and began his medical studies. He quickly abandoned them, however, when he was offered a post as lecturer in Lyons. Through a change in plans, however, he was appointed to a course in zoology at the Faculty of Sciences of Nancy in 1890. He spent the rest of his career there, becoming assistant professor in 1896, deputy professor in 1897, and full professor of zoology in 1898; he held that professorship until his retirement in 1937. He consistently refused all appointment offers from Paris.
Knowledgeable in the interpretation of organic structures and able to discern the affinities between living fortas and to increase understanding of present species by comparing them with fossil species, Cuenot studied completely different groups, from Protista and Echinodermata to Siphunculata and Tardigrada. He made detailed observations of the fauna of Lorraine and the Arcachon Basin, describing many new species and detailing their ecology and ethology.
Cuénot defined the phases of the sexual cycle of the Gregarina; and using ingenious and sophisticated methods, he analyzed the absorption and excretion processes of Invertebrata. He also studied reflex bleeding, regeneration of antennae, caudal autotomy in rodents, and the homochrome phenomenon. Cuénot became interested in sex determination at a time (1893) when the chromosome was still unknown; he proved experimentally that sex was not influenced by exterior conditions and acknowledged that determination took place as early as the egg stage. He believed that armadillos from the same litter are true twins born of polyembryony; this was later confirmed.
Cuénot next studied heredity. Through crossbreeding mice he discovered that Mendel’s laws were applicable to animals; at almost the same time Bateson conducted similar research on the hen and guinea pig. By extending Mendelism to the animal kingdom, Cuénot became a pioneer in genetics. In analyzing the heredity of pigmentation he discovered that “albinism is a mask” capable of hiding profound genetic differences in coloring; thus he offered an explanation of the phenomenon of atavism, the reappearance of an ancestral characteristic.
Crossbreeding of yellow mice provided Cuénot with the first example of lethality and the discovery of lethal genes (1905); he attributed the impossibility of obtaining pure yellow mice to selective fertilization; this hypothesis was incorrect, but the phenomenon was nevertheless real. Later Kirkham discovered that the pure yellow embryos died in the mother’s uterus. Cuénot’s genetic studies are still of interest in the heredity of variegation, experimental production of atavism, the intransmissibility of cataract caused by naphthalene, and the heredity of predisposition to cancer. He was one of the first to suggest a comparison between the activity of a gene and that of an enzyme.
After World War I, Cuénot became interested in evolution, especially in adaptation and speciation. He attributed an important role to mutation, but disputed the all-powerful role of natural selection. In an attempt to explain the harmony between form and environment he proposed the theory of preadaptation: the “empty space” or “ecological niche” is populated with mutants already showing characteristics adapted to the conditions of the “empty space.”
Cuénot disliked getting involved in the question of the transmission of acquired characteristics. A “dissatisfied mutationist,” he would not admit that the randomness of mutations by natural selection could have led to the development of complex organs. He was especially interested in the small but numerous function-specific assemblages of organs in living creatures that, by their structure and function, suggest tools made by man. This principle led Cuénot to a purified neo-finalism, removed from any sort of absolute providentialism; at the end of his life he favored a broad type of pantheistic monism. He was skeptical and independent, refusing to accept illusory solutions.
I Original Works. Cuénot’s papers include “Contribution à l’étude anatomique des astérides,” Archives de zoologie expérimentale, 2nd ser., supp. 5 (1887); “Études physiologiques sur les gastéropodes pulmonés, sur les orthoptères, sur les oligochètes,” in Archives de biologie, 12 (1892), 683–740; 14 (1895), 293–341; 15 (1897), 79–124; “L’excrétion chez les mollusques,” ibid., 16 (1899), 49–96; “Sur la détermination du sexe chez les animaux,” in Bulletin scientifique de la France et de la Belgique, 32 (1899), 462–535; “Recherches sur l’évolution et la conjugaison des grégarines,” in Archives de biologie, 17 (1901), 581–652; “La loi de Mendel et l’hérédité de la pigmentation chez les souris,” in Compte rendu hebdomadaire des séances de l’Académie des sciences, 134 (1902), 779–781, and Compte rendu des séances de la société de biologie, 54 (1902), 395–397; “Sur quelques applications de la loi de Mendel,” ibid., 397–398; “Hérédité de la pigmentation chez les souris noires,” ibid., 55 (1903), 298–299; “Transmission héréditaire de pigmentation par les souris albinos,” ibid., 299–301; “Sur quelques anomalies apparentes des proportions mendéeliennes (Géme note),” in Archives de zoologie expérimentale, 4th ser., 9 (1908), vii-xvi; “Théorie de la préadaptation,” in Scientia, 16 (1914), 60–73; “Sipunculiens, échiuriens, priapuliens,” in Faune de France, 4 (1922); “Tardigrades,” ibid., 24 (1932); “Contribution à la faune du Bassin d’Arcachon, IX,” in Bulletin de la station biologique d’Arcachon, 24 (1927), 229–308; “L’inquiétude métephysique,” in Mémoirs de l’Académie de Stanislas, 6th ser., 25 (1928); “Génétique des souris,” in Bibliographia genetica, IV (1928), 179–242; Echinodermes, Traité de zoologie no. 11 (Paris, 1948); Onycophores, tardigrades, pentastomides, Traité de zoologie no. 6 (Paris, 1949); Phylogenèse du régne animal, Traité de zoologie no. 1 (Paris, 1952); Echinodermes fossiles (hétérostélés et cystidés), Traité de paléontologie no. 3 (Paris, 1952); and Phylogenèse du règne animal, Traité de paléontologie no. 1 (Paris, 1952), written with A. Tétry.
His books are Les moyens de défense dans la série animale (Paris, 1892); L’influence du milieu sur les animaux (Paris, 1894); La genèse des espèces animales (Paris, 1911, 1932); L’adaptation (Paris, 1925); L’espèce (Paris, 1936); Introduction à la génétique (Paris, 1936), written with J. Rostand; Invention et finalité en biologie (Paris, 1941, 1946); and L’évolution biologique (Paris, 1951), written with A. Tétry.
II. Secondary Literature. An article on Cuénot’s life and works was published by R. Courrier in Académie des sciences (Paris, 1952); it consists of a biography, complete bibliography, and references to obituaries. A memoriam on the centennial of his birth was published in Académie des sciences (Paris, 1967); it consists of texts of speeches by A. Tétry, W. Delafosse, P. Marot, F. Moreau, J. Rostand, P.-P. Grassé, and P. Brien. The following were written by A. Tétry: “Le sort de la notion de préadaptation,” in Proceedings of the XIV International Congress of Zoology, Copenhagen 1953 (Copenhagen, 1956), pp. 159–160; “La place du laboratoire d’Arcachon dans l’oeuvre de L. Cuénot. Colloque international sur l’histoire de la biologie Marine,” in Vie et milieu, supp. 19 (1965), 265–273; and “Les ‘incertitudes’ de l’évolution biologique,” in Année biologique, 6 (1967), 573–578.