In the early twentieth century, Tatsuo Aida in Japan, Øjvind Winge in Denmark, Richard Goldschmidt in Germany, and Calvin Bridges in the United States all developed different experimental systems to study the genetics of sex reversal. These locally specific experimental systems grounded these experimenters’ understanding of sex reversal as well as their interpretation of claims regarding experimental results and theories. The comparison of four researchers and their experimental systems reveals how those different systems mediated their understanding of genetic phenomena, and (...) influenced their interpretations of sex reversal. (shrink)