The fifth chapter documents the active growth during the first two decades of the twentieth century of a British ‘national’ eugenics initiated by Francis Galton and the formation of a transnational eugenics movement that spread rapidly around the world, including to Russia. The infiltration of eugenics (in its Anglo-American ‘eugenics,’ French ‘eugénnétique,’ and German ‘Rassenhygiene’ versions) into Russian professional and popular discourse on human reproduction, heredity, development, and evolution became the major stimulus for the ‘resurrection’ of Florinskii’s long-forgotten work in the new, Soviet Russia that emerged out of the firestorms of World War I, the Bolshevik Revolution, and the ensuing Civil War, which engulfed the former empire from 1914 through 1921. Mikhail Volotskoi, an anthropologist and a founding member of the Russian Eugenics Society established in Moscow in 1920, discovered, actively popularized, and in 1926 issued a new edition of Florinskii’s treatise. For Volotskoi, this tract was more than a historical curiosity. He found in Florinskii’s book a model and justification for what, in contrast to Galton’s ‘bourgeois’ eugenics, he saw as a ‘proletarian’ eugenics. Building on Florinskii’s ideas, he advanced a pointed ‘Marxist’ critique of Galtonian eugenics and its numerous followers in Russia and elsewhere. Volotskoi elaborated a concept of ‘bio-social’ eugenics and launched several research projects inspired by Florinskii’s notion of ‘conditions conducive’ to either perfection or degeneration, investigating the ‘eugenic’ effects of various factors, ranging from occupational hazards to women’s fashion. In contrast to the first publication of Florinskii’s book, the new edition did not go unnoticed.