August Weismann and the Growth of Biological Understanding Between Darwin and the Rediscovery of Mendel

Abstract

The last four decades of the nineteenth century, between the publication of Darwin’s On the Origin of Species in 1859 and the rediscovery of Mendel’s work by Carl Correns, Erich von Tschermak and Hugo de Vries in 1900, were quite tumultuous for biology. Our understanding of the living world was greatly enhanced, both in detail and conceptual nuance, during this period, especially with regard to heredity, development, and evolution. The German biologist August Weismann (see accompanying Article-in-Box for a biographical sketch) was one of the most important figures in biology during those eventful decades and is considered by many to be the most significant evolutionist in the first fifty years after Darwin. He is perhaps best known for his opposition to the admissibility of any inheritance of acquired characteristics. This was based on his notion of the sequestration of germline cells (that would eventually give rise to gametes) early in embryonic development, making it impossible for changes in somatic cells to be transmitted to offspring. However, his work also addressed many other fundamental issues in heredity, development and evolution.