BONNET, CHARLES (172o-1793), Swiss naturalist and philosophical writer, was born at Geneva on March 13 1720, of a French family. He made law his profession, but his favourite pursuit was the study of natural science. In 1740 his paper to the Academy of Sciences containing a series of experiments estab lishing what is now termed parthenogenesis in aphides or tree-lice, obtained for him the honour of being admitted a corresponding member of the academy. In 1741 he began to study reproduction by fusion and the regeneration of lost parts in the freshwater hydra and other animals; and in the following year he discovered that the respiration of caterpillars and butterflies is performed by pores, to which the name of stigmata has since been given. In he was admitted a fellow of the Royal Society; and in the same year he became a doctor of laws.
In 1745 appeared his Traite d'insectologie, and in 1754 his Recherches sur l'usage des feuilles dans les plantes; in which he suggests that plants possess powers of sensation and discern ment. But Bonnet's eyesight, which threatened to fail altogether, caused him to turn to philosophy. In 1754 his Essai de psychologie was published anonymously in London. This was followed by the Essai analytique sur les facultes de fame (Copenhagen, 1760), in which he develops his views regarding the physiological condi tions of mental activity. He returned to physical science, but to the speculative side of it, in his Considerations sur les corps organises (Amsterdam, 1762), designed to refute the theory of epigenesis, and to defend the doctrine of pre-existent germs. In his Contemplation de la nature (Amsterdam, 1764-65) he sets forth the hierarchy of all creatures, and in his Palingenesie philo sophique (Geneva, 1769-70), treats of the past and future of living beings, and supports the idea of the survival of all animals.
Bonnet's life was uneventful, and he seems never to have left Switzerland. Between 1752 and 1768 he was a member of the council of the republic. He died at Genthod, near Geneva, May 20, 1793. (See EVOLUTION, history.) Bonnet's complete works appeared at Neuchatel in 1779-83, partly revised by himself. An English translation of certain portions of the Palingenesie philosophique was published in 1787, under the title, Philosophical and Critical Inquiries concerning Christianity. See also A. Lemoine, Charles Bonnet (185o) ; the duc de Caraman, Charles Bonnet, philosophe et naturalists (1859) ; Max Offner, Die Psychologie Charles Bonnet (Leipzig, 1893) ; Joh. Speck, in Arch. f. Gesch. d. Philos. x., xi. (1897) , p. 58 f oll., xi. (1898), pp. 1-211 ; J. Trembley, Vie privee et litteraire de Charles Bonnet (Bern,