Mangin, Louis Alexandre

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MANGIN, LOUIS ALEXANDRE

(b. Paris, France, 8 September 1852; d. Grignon, France, 27 January 1937)

botany.

Mangin was professor of cryptogamy at the Muséum National d’Histoire Naturelle in Paris from 1906 to 1932; he served as director of that institution concurrently from 1920. He was a member of the Académie des Sciences, its vice-president in 1928, and its president in 1929. His researches were not limited to the cryptogams, although he did write on micromycetes, species of Penicillium, and the phylogeny of Atichiales, as well as studying the composition and seasonal and geographical variations of the phytoplankton collected on the Antarctic expedition of the Pourquoi-Pas? (directed by J.-B. Charcot) and on the North Sea expedition of the Scotia. He also did significant work in plant anatomy and physiology and phytopathology, and made important contributions to plant histology.

Mangin’s work in plant anatomy included a study of the vascular system of the monocotyledons. He also established that adventitious roots arise from a special meristem (which he called “souche dictogène”) which is seated in the pericycle; he thought, however, that only the central core and the bark of the adventitious root are formed by this apical meristem, the root cap being constituted from the internal layers of the bark.

In plant physiology Mangin observed the waxy cuticle and determined thereby the importance and function in respiration of the stomata. In collaboration with Gaston Bonnier he published a series of papers on their joint researches into plant respiration within various experimental environments. Mangin and Bonnier also devised an apparatus—consisting of a gas bubble imprisoned between two columns of mercury and subjected successively to the actions of caustic potash and pyrogallic acid—for the purpose of rapidly analyzing the atmosphere surrounding plants. They were particularly concerned with the ratio that existed between the oxygen absorbed and the carbon dioxide discharged by each species (which they found to be constant).

Mangin may be considered one of the founders of phytopathology; he furthered its study as the guiding spirit of the Société de Pathologie Végétale et d’ Entomologie Agricole de France. He published studies on mycorrhiza of fruit trees (1889); on wheat foot-rot (which he showed to be a consequence of the association of the grain with several species of fungus, including Ophiobolus graminis and Leptosphaeria herpotrichoides); and, with P. Viala, on vine diseases, especially “phtyriose,” which they found to be due to a cochineal insect associated with a polypore, Bornetiacorium. He also did research on root rot in chestnut trees and needle-shedding disease in firs.

As a histologist, Mangin pioneered in the use of color reactives for microscopic investigation. In 1890 to 1910 he employed a whole series of azoic dyes in the work on the composition of plant membranes whereby he established the characteristics of cellulose and pectin materials and showed that the young membranes of vascular plants always contain these compounds. In 1890 he reported his discovery of callose to the Academy, and went on to describe its microchemical properties and to define its diverse forms according to the condensation of the molecule. He showed callose to exist in all membranes and in such special calcified formations as cystoliths; demonstrated gums and mucilages to be the end products of the jellification of cellular membranes; and recorded important observations on the constitution of the membranes of pollen grains. In his final investigations on the subject Mangin ascertained the essentially variable constitution of the cellular membranes in mushrooms—cellulose and callose in Peronosporaceae, cellulose and pectin compounds in Mucoraceae, and various combinations of callose in other groups.

BIBLIOGRAPHY

I. Original Works. Mangin’s report on callose is “Surla callose, nouvelle substance fondamentale existant dans la membrane,” in Comptes rendus hebdomadaires de l’Académie des sciences, 110 (1890), 644–647. His collaborative work with Bonnier is summarized in “La fonction respiratoire chez les végétaux,” in Annales des sciences naturelles (botanique), 7th series, 2 (1885), 365–380, which draws upon the papers that appeared in Annales, 6th series, 17 (1884); 18 (1884), 293–381; and 19 (1885), 217–255.

Mangin was the author of several textbooks, including Botanique élémentaire (1883); Éléments de botanique (1884);Cours élémentaire de botanique(1885); and Anatomie et physiologie végétale (1895).

II. Secondary Literatur. Magnin’s work with Bonier is discussed in M. H. Jumelle, “L’oeuvre scientifique de Gaston Bonnier,” in Revue générale de botanique, 36 (1924), 289–307.

Maurice Hocquette