Linnaeus' Peloria: The history of a monster.

The so-called Peloria case has been discussed repeatedly in world literature since the discovery of the five-spurred Linaria in 1742 and its description by Linnaeus in 1744. In 1742 a young Uppsala botanist found a peculiar specimen of the common toad-flax (now named Linaria vulgaris L.) on an island in the Stockholm archipelago. The plant, which had spread vegetatively, possessed five spurs instead of one spur, a characteristic of the common toad-flax. The material was presented to Linnaeus, who became quite excited. The finding was contrary to his concept that genera and species had universally arisen through an act of original creation and remained unchanged since then. In a famous thesis of 1744, Linnaeus called the deviating plant 'Peloria', Greek for 'monster'. The case of pelorism was discussed later on by a great number of famous writers and scientists including, for example, Goethe, Darwin, Naudin, De Vries and Stubbe. Parallel types were found in numerous species of other genera and families. Such aberrant forms are caused by spontaneous mutation. The history, mode of origin, morphology, inheritance and distribution of different Peloria mutants are discussed in the paper.