ABSTRACT
Just as the term biology was coined at the beginning of the nineteenth century to replace natural philosophy, the term genetics was coined at the beginning of the twentieth century to separate new forms of scientific inquiry from previous studies of generation, inheritance, or heredity. Although genetics, embryology, and evolution were originally inseparable aspects of biology, during the twentieth century they became complex and separate disciplines. In the 1920s classical genetics, often referred to as Mendelism, was still a tentative and contested branch of natural history, barely separated from embryology, the study of development and growth. By the 1950s genetics had emerged as a powerful new unifying principle at the heart of the life sciences.
