Lamarckian

La·marck \lä-ˈmärk\ , Jean–Baptiste–Pierre–Antoine de Monet de (1744–1829), French botanist and biologist. Lamarck produced voluminous botanical writings and also made substantial contributions to comparative anatomy and the study of invertebrates. In 1801 he introduced his classification of invertebrates, a classification that remains largely accepted. From 1815 to 1822 he published his major work, a multivolume natural history of invertebrates. He is credited with being the first to distinguish invertebrates as a taxonomic group from vertebrates. In 1809 he published a work summarizing his views on zoological philosophy. Here he presented two major “laws”: (1) organs are improved with repeated use and weakened by disuse (2) new characteristics are acquired through interaction with the environment and are passed on to progeny. Although his general idea of evolutionary change was later controverted by Darwin, Lamarck is important because his thesis denied the old notion of the immutability of species, thereby preparing the way for later explanations of the transformation and evolution of plants and animals.