Mutter Krause, her daughter Erna and her son Paul live in a tenement in the poorer section of Berlin's Wedding district. Along with them lives "the Tenant", his soon-to-be bride Friede, who works as a prostitute, and her child whose name isn't revealed in the film. Mutter Krause is a quiet, long-suffering old woman who earns what little she can delivering newspapers. However, Paul is an alcoholic and spends all her money on drink. Mutter Krause can't pay back the money she owes the man whose newspapers she delivered and he accuses her of stealing and threatens her with arrest. Mutter Krause must then pawn her last valuable possession, a treasured memento of her late husband. Paul then breaks into the same pawn shop. He gets away but is later arrested. Meanwhile, Erna begins dating a young man with Communist views, who turns Erna to Communism and also helps her earn the money her mother needs by more honest means.
A Socialist Realist distortion of Dr. Paul Kammerer's experiments in the inheritance of acquired character(istic)s -- the (not entirely anti-Darwinian) conjecture that certain changes the environment produces in an individual may spontaneously appear in the next generation. As recounted in Arthur Koestler's The Case of the Midwife Toad (1971), Kammerer (1880-1926) claimed that darkened footpads he had artificially induced in a toad had been passed on to its offspring. When it was discovered that his critical specimen had been injected with ink (though why and by whom is still unknown), his credibility was destroyed and he apparently suicided. Richard Goldschmidt's synopsis of the film in "Research and Politics," Nature (1949), mocks it as Soviet propaganda in support of the inheritance of acquired characters: The importance attached to the subject is revealed by the facts that none other than the then all-powerful [People's] Commissar for [Public] Education, the highly ...
