The rediscovery of Mendelism in agricultural context: Erich von Tschermak as plant-breeder.

Why was Mendelism rediscovered? One way in which historians have addressed this issue is to look at wider trends in research during the 1890s of which the rediscoverers were part. Quite a lot is known about one such research tradition, namely the attempts to resolve the question of evolutionary mechanism through the use of varietal crosses. But another relevant research tradition is still largely unknown: the work of commercial breeders, several of whom were using hybridisation by the 1890s. In this paper I begin by looking at Tschermak's initial career, the sequence of events by which he came upon Mendel's work, and why he was excited by what he read. Then I place Tschermak's early work in the context of commercial plant-breeding in German-speaking Europe toward the end of the 19th century. Finally I look again at the question of Tschermak's somewhat ambivalent relationship to Mendelism after 1900. I argue that his initial misunderstanding of the concept of segregation was due to the fact that he approached Mendel's work with the perspective of a breeder rather than that of a geneticist.