Bonnet, Charles

(b. Geneva, Switzerland, 13 March 1720; d. Geneva, 20 May 1793)

natural history, biology, philosophy.

Bonnet was the son of Pierre Bonnet, whose family lived at Thônex, near Geneva, and of Anne-Marie Lullin. A mediocre student, he was gifted neither in languages nor in mathematics; moreover, he was hindered by increasing deafness, which exposed him to the taunts of his playmates. His father decided to engage a private tutor, a Dr. Laget, who played a prominent part in stimulating the boy’s early interest in the natural sciences. In 1736, Bonnet avidly read Pluche’s study Le spectacle de la nature. The following year, he read the memoirs of René Réaumur and began a correspondence with the great scientist. These were decisive steps. In 1738 he submitted an essay on entomology to the Academy of Sciences of Paris. His father, however, looked unfavorably upon a career in the natural sciences, and Bonnet agreed to study law instead. In 1744 he received a doctorate in law. He married Jeanne-Marie de La Rive in 1756 and retired to his wife’s estate at Genthod, near Geneva. All his life Bonnet had to contend with precarious health. In addition to being deaf, he became, while still young, almost completely blind, then began to suffer severe asthma attacks.

Bonnet is considered one of the fathers of modern biology. He is distinguished for both his experimental research and his philosophy, which exerted a profound influence upon the naturalists of the eighteenth and nineteenth centuries.

Bonnet was twenty-six when he made his first and greatest discovery, the parthenogenesis of the aphid. He very carefully raised a female spindle-tree aphid, then observed that she produced ninety-five offspring without mating. Virginal generation was therefore possible. Bonnet wrote a note for the Academy of Sciences, which, on Bernard de Fontenelle’s recommendation, appointed Bonnet a corresponding member Then, taking up Réaumur’s (1712) and Abraham Trembley’s (1740) research on regeneration, Bonnet began his observation of rainwater worms of the species lumbriculus. He demonstrated that one of these worms, cut into twenty-six pieces, would become twenty-six perfectly constituted new worms. In 1745, he published several monographs on this subject. Bonnet devoted another work to the regeneration of a snail’s head (1769), and in 1777 he dealt with regeneration of the limbs of a triton.

Bonnet’s research induced him to study the breathing of caterpillars and the locomotion of ants. In 1745 he published the comprehensive Traité d’insectologie, a work that entitles him to consideration as an early exponent of experimental entomology. After 1750 Bonnet published only a few studies on zoology; henceforth, his research was in plant physiology. In the preface to a remarkable work entitled Recherches sur l’usage des feuilles dans les plantes (1754). Bonnet wrote:

Insects held my attention for some years. The strenuousness with which I worked on this study strained my eyes to such an extent that l was forced to interrupt it. Deprived thus of what had so far been my greatest pleasure, I tried to console myself by changing subjects. I then turned toward the physics of plants—a matter less animated, less fertile in discoveries but of a more generally recognized usefulness.

In the Recherches, Bonnet grouped five memoirs, all of which were of prime importance for plant biology: He precisely described the characteristics of the nutrition of leaves and of their transpiratory phenomena. Although he did not know the kinds of gases (oxygen and carbon dioxide) produced and absorbed by green leaves exposed to light, Bonnet made very careful observations on their production. For his masterly experimentation, Bonnet should be considered one of the first naturalists to investigate experimentally the question of photosynthesis. He studied the movement of leaves and discovered the epinastic phenomena; he observed the position of leaves on the axis of the stalk and collected a great many anatomic facts; he returned to experiments on etiolation, on the movement of the sap, and on teratology. Bonnet could no longer observe with his own eyes, so he surrounded himself with collaborators, all of whom later became distinguished naturalists—for example. François Huber, the bee specialist, and Jean Sénebier, famous for his research on photosynthesis. The collaborators performed innumerable tests on hybridation of corn, wheat, and darnel. Bonnet was opposed to the theory of transmutation of the species and may rightly be considered a forerunner of Lamarckism through his definition of his original concept of the “chain of beings”—parts of which, it is true, he had borrowed from Leibniz.

Next Bonnet turned to philosophy and methodology. A true theoretician of biology, he exercised an enormous influence in this field and maintained a correspondence with almost all the scientists of his time. He published works that caused a considerable stir—among them Essai de psychologie (1754) and Essai analytique sur les facultés de l’âme (1759). Bonnet then returned to theoretical biology, publishing Consiéderations sur les corps organisés (1761), Contemplation de la nature (1764), Palingenesiegénésie philosophique (1769), and Recherches philosophiques sur les preuves du chirstianisme (1771).

Bonnet was an enthusiastic champion of preformation, the theory postulating that the animal already existed in miniature in the germ cell. His discovery of parthenogenesis was, to him, proof that the female germ cell contains the preformed individual. Thus Bonnet became a fervet partisan of ovism. Many other naturalists, such as Albrecht von Haller, supported this thesis—a surprising one nowadays—of preformation. Yet Bonnet was less doctrinaire than his colleagues; he supported, for example, a very elastic thesis of the germ cell, which, according to him, was not only “an organized body reduced in size…” but “every kind of original preformation out of which may result an organic whole, as of his immediate principle.” This theory, which Bonnet christened “palingenesis,” set forth the functional and structural notion of the cell, which was not stated formally until a hundred years later.

Bonnet was not only a remarkable experimentalist in his younger years and a theoretician with fertile ideas: he was the instigator of a whole series of fundamental experiments. His extraordinary imagination suggested projects that his poor eyesight prevented him from carrying out; he treated these projects in numerous works, and above all he discussed them with his many correspondents. For instance, he suggested to Lazzaro Spallanzani that he carry out experiments on artificial insemination.

Mention must be made of the importance of Bonnet’s methodological work. Of course he was—particularly in his more important writings—a theoretician, but a theoretician who experimented widely. Every observed fact, every proposed theory, gave Bonnet the opportunity to suggest the technique best suited for progress toward a solution. In his voluminous correspondence (he purportedly wrote over 700 letters annually), philosophical treatises, notes submitted to the Academy, and his most important monographs, he showed himself constantly preoccupied with methodological problems. Well before Claude Bernard, Bonnet attributed a preponderant role in scientific research to the “art of observing.” The quality of his work fluctuates greatly, so it is not surprising that Bonnet is not appreciated without preservations. He sought after truth with courage and preserverance, was distrustful of his own hypotheses, and was ready to accept the conclusions of his strongest adversaries, if convinced that they were right. The personal qualities of Charles Bonnet, as much as his writings, justify the extraordinary reputation that he enjoyed in his lifetime and that survives today.

BIBLIOGRAPHY

I Original Works. Bonnet’s writings include Triaté d’insectologie (Paris, 1745); Essai de psychologie (Leiden, 1754); Recherches sur l’usage des feuilles dans les plantes (Leiden, 1754); Essai analytique sur les facultés de l’ame (Copenhagen, 1760); Considérations sur les corps organisés (Amsterdam, 1762); Contemplation de la nature, 2 vols. (Amsterdam, 1764); La palingénéssie philosophique (Geneva, 1769); Recherches philosophiques sur les preves du chirstianisme (Geneva, 1771); and Oeuvre d’histoire naturelle et de philiosophie, 8 vols, in 4°, 18 vols. in 8° (Neuchâtel, 1779–1783).

II. Secondary Litterature. Works on Bonnet include G. Bonnet, Charles Bonnet (Paris, 1929), a thesis; R. de Caraman, Ch. Bonnet, philosophe et naturaliste, sa vie et ses oeuvers (Paris, 1859); E. Claparéde, La psychologie animale de Ch. Bonnet (Geneva, 1909); J. Rostand, Esquisse d’une historie de la biologie: Un preformationniste—Ch. Bonnet (Paris, 1945), pp. 65–80, and Hommes d’autrefois et d’aujourd’hui: Ch. Bonnet de Genéve (Paris, 1966), pp. 65–80, and Hommes d—autrefois et d—aujourd—hui: Ch. Bonńet (Paris, 1966), PP. 7—45; R. Savioz, La philosophic de Ch. Bonnet de Genève (Paris, 1948); A. Schubert, Die psychologie von Bonnet und Tetens (Zurich, 1909), a thesis; and J. Trembely, Mémorie pour servir á l’histoire de la vie et des ouvrages de M. Ch. Bonnet (Bern, 1794).

P. E. Pilet