 In order to treat patients of other species , doctors must download into their brains " Educator tapes " containing the necessary medical knowledge , and these tapes also transmit the personalities of their donors . As a result doctors have to struggle with the tastes imported from their donors , ranging from a dislike of their own species ' normal food to sexual attraction for members of the donor 's species . Other running gags include the acerbic tongue of the Chief Psychologist and one very senior non @-@ human doctor 's love of gossip , especially about the sexual behavior of other species . 
