Cytogenetic "Plasmas," Hereditary Elements Revisited, and the Sonderweg of Botanical Genetics

What did it mean for something to be the “material basis” of life, or heredity, permeability, or metabolism before molecular biology? What conceptions of matter did biologists rely on as they tackled new research topics? In the latter half of the nineteenth century (and well into the twentieth) it was biological orthodoxy that protoplasm was the “material basis of life,” so much so that the protoplasm’s protean nature spawned what Robert Brain has called “protoplasmania”—an aesthetic, cultural, and scientific obsession with the so-called “living substance.” But life was not the only thing biologists in the nineteenth century studied, and in this paper I will show how other areas of biology even more particular “plasmanias” took hold, as other vital phenomena gained their own “plasms” in due course. The idioplasm, germ plasm, nucleoplasm, stereoplasm, endo- and ecto-plasms, even cytoplasm, became the calling cards for newly emerging (and contested) problem areas in cellular anatomy and physiology. In particular, I will argue that botanists, far more so than zoologists, insisted on tying hereditary and developmental phenomena to their material bases within the cell. From the beginning with Carl Nägeli’s idioplasm theory, botanical theories of “genetics” always made reference to the material reality of hereditary factors via physical chemistry—albeit a physical chemistry specific to plant physiology. By shifting the historiographical locus of cell theory and hereditary theory to the history of botany, I will show how hereditary theory encountered chemical theory, several generations before the revolution in molecular genetics.