Nature's Enigma: The Problem of the Polyp in the Letters of Bonnet, Trembley and Reaumur

Two striking discoveries made 1740 a turning point in the history of eighteenth-century biology. Charles Bonnet established that aphids could reproduce without male fertilization. Shortly afterwards Abraham Trembley proved that a tiny aquatic animal, the fresh water polyp, or hydra, could regenerate from cuttings like some plants. The discovery of the polyp was important because of the disturbing metaphysical issues it raised. In their letters written during the decade of the 1740s to Reaumur, the great French Academician, both Trembley and Bonnet referred to the polyp as an enigma. Not only did it seem to present a new mode of animal reproduction, previously unsuspected, but it called into question the prevailing mechanistic view of animal biology and brought into focus the problem of animal soul.