A brief, informal and popular treatment of the biology of sex. Sex, declares the author in a cooling plunge into elementary reproduction, is a matter of single cells. She then discusses various methods of asexual and sexual reproduction among the lower orders, observing that in exchange of chromosomes the individual is sacrificed for the sake of the species, unlike the duplication in binary fission. ""Genetic cards are shuffled"" increasing the adaptivity potential of the species. Secondary sex characteristics, based on the mechanics of reproduction, are discussed and human mating is viewed as purposeful journeys of sperm and egg. Ms. Keller reviews historical discoveries and bloopers concerning the mystery of conception, and birth control methods are presented clearly. Unfortunately the author tends to be overly cute at times and unprofessionaly simplistic -- Is the male sea horse really the wild brother of a male babysitting in a laundrymat?