Mind Switch
Damon Knight
 In the year 2002, the Berlin Zoo acquires a new specimen: "Fritz", a biped from "Brecht's planet." Fritz is intelligent, and his keepers treat him with a mix of courtesy and disdain; he is kept in a display with another (presumably female) biped and the two are required to work for a living, transcribing tapes made by explorers to their planet. One day, Martin Naumchik, a human male, is visiting the zoo when his personality and that of the biped are interchanged. The switch is the unintended consequence of an experiment in time travel that takes place at another location. The remainder of the story follows the two characters as they come to terms with their new bodies and new feelings. Martin quickly becomes aware of the degradation of being a zoo animal, while Fritz is forced to cope with life in a confusing and threatening alien society. Martin tries, and fails, to convince his captors that he is imprisoned in the biped's body; the biped, in Martin's body, eventually comes into contact with Martin's colleagues and his lover, and manages to continue with Martin's life. The novel also deals wryly with the theme of sexual identity. Because Fritz is provided with inguinal glands resembling a human male's, he is presumed to be male. But it turns out that the organ has nothing to do with reproduction: Fritz is a female, and the smaller primate with whom he shares a cage is a male. To reproduce, the female aggressively bites off an egglike knob from the male's forehead containing the semen. Martin (in Fritz's body), and the reader, only learn this at the end of the novel, when he is overcome by passion and commits the act.