Bonnet, Charles, naturalist and philosophical writer, was born at Geneva in 1720, never left his native country, and died in 1793. Nominally in the legal profession, he early devoted himself to natural history. In 1740 he communicated to the Academie des Sciences his experiments on aphides (q.v.), showing their parthenogenetic reproduction. He then experimented on the reproduction of lost parts in worms, and the respiratory stigmata of insects, publishing in 1745 his Traite d'Insectologie, with an introduction on embryonic development, and the existence of a graduated scale of living beings. In 1754 he published his Traite de l'usage des feuilles, in which he showed, among other points, the heliotropism and hydrotropism of leaves when growing. Failing eyesight caused Bonnet to turn his attention to speculative science. In 1754 he published Essai de Psychologie: in 1760, Essai sur les facultes de l'Ame; in 1762, Considerations sur les corps organises; in 1764-5, Contemplation, de la Nature; and in 1769, Palingenesie Philosophique. He held that a multitude of germs were originally created, containing in themselves a power of advance towards, though not to, perfection; that we have an immaterial mind, but that all knowledge originates in sensations, memory being conditioned by the increased flexibility produced in nerves by sensation; and that happiness is the end of human existence.