(b. Paris, France, 1853; d. Paris, 30 December 1922)
During the last half of the nineteenth century, botany changed from a descriptive science to an experimental one; Gaston Bonnier was one of the botanists responsible for this transformation. A fervent advocate of the experimental approach, he made several discoveries that, although not revolutionary, were of considerable importance to the growth of the science.
Bonnier’s father and grandfather were both professors of law, but he seems to have been interested in botany from the very beginning of his academic career. He was a student at the École Normale in Paris and taught there for several years before succeeding to the chair of botany at the Sorbonne in 1887.
In 1879, Bonnier received the D.S.N. upon publication of his thesis, an anatomical and physiological study of the nectary organs. This thesis earned him the Prix de Physiologie Expérimental of the Paris Academy of Sciences (of which he was made a member in 1896). Traditionally the nectary organs had been one of the best weapons in the arsenal of teleology; it was said that they existed solely to produce nectar, which itself existed solely to attract bees, the agents of cross-fertilization. Bonnier demonstrated the absurdity of this argument by proving that in many species of plants a bee can easily collect nectar without going near the pollen-carrying stamens. He proved that the nectaries are important to the plant chiefly because they store the excess sugar that is needed during periods of increased physiological activity, nectar being only an incidental by-product of transpiration.
The decade after the publication of his thesis was the most productive period of Bonnier’s career. Between 1880 and 1882 he studied (in collaboration with Philippe van Tieghem) the physiological activity of seeds, grains, and bulbs and discovered that they are not physiologically “dead,” as had been thought. From 1883 to 1885, he published several lengthy papers on plant respiration in collaboration with Louis Mangin. At that time botanists had just begun to realize that respiration and photosynthesis are different processes. Bonnier and Mangin were particularly interested in the relationship between respiration and various environmental conditions. Of their many discoveries, the most crucial was the fact that respiration proceeds most rapidly in the absence of light. They also developed an apparatus for determining the ratio of carbon dioxide discharged to oxygen absorbed at any given moment and demonstrated that this ratio remains constant for each species, no matter what the respiration rate may be at any given time. Finally, toward the end of this decade, Bonnier branched out into an entirely different field—lichenology—and settled a long-standing botanical debate by proving that lichens are composed of two symbiotic forms, an alga and a fungus, the latter reproducing by means of spores.
Bonnier became increasingly involved in administrative affairs. He was deeply concerned about the development of botany as a discipline, and he had helped to organize a separate faculty in natural sciences while at the École Normale. Botanical facilities were inadequate al the Sorbonne, and in 1889 Bonnier was able to remedy that situation by founding and directing the Laboratoire de Biologic Vegetale at Fontainebleu. In 1890 he took on the additional burden of editing a new botanical journal, Revue generate de botanique. He continued in that post, as well as in the others, until his sudden death.
From 1890 to 1922, most of Bonnier’s scientific work was concerned with the relationship between structure and environment. In this connection he studied the differences between alpine and arctic plants, and attempted to find correlations with differences in their habitats. He also undertook studies of heat production and pressure transmission in plants. During this time he wrote extensively, producing several botanical handbooks, a few popularizations, a basic text, and, finally, his twelve-volume masterpiece, Flore complète . . . de France, Suisse et Belgique, some of which was published posthumously.
Articles by Bonnier include “Les nectaires,” in Annales des sciences naturelles (botanique), 6th series, 8 (1879), 5–212, and “Recherches sur la vie ralentie et sur la vie latents,” in Bulletin de la Societé Botanique de France, 27 (1880), 83–88, 116–112; 29 (1882), 25–29, 149–153. A summary of the work done by Bonnier and Mangin can be found in “La function respiraoire chez les végétaux,” in Annales des sciences naturelles(botanique) 7th series, 2 (1880), 365–380; the original papers are in Annales, 6th series, 17 (1884), 210–306; 18 (1884), 293–381; 19 (1885), 217–255. A representative article of several on alpine and arctic plants is “Les plants arctiques comparées aux mêmes espèces des Alpes et des Pyrennées,” in Revue générale de botanique, 6 (1894), 505–527. Of his books, other than practical guides such as Nouvells flore pour la détermination facile des plants (Paris, 1887), the most important are his text, Cours de botanique, 2 vols.(Paris, 1901), and his Flore complète illustée et en couleurs de France, Suisse et Belgique, 12vols.(Paris, 1912–1934).
For a discussion of Bonnier’s work, see M. H. Jumelle, “L’oeuvre scientifique de Gaston Bonnier,” in Revue générale de botanique, 36 (1924), 289–307.
Ruth Schwartz Cowan