Operations, such as vasectomy and oviduct transfer, are performed on anesthetized animals. It is essential that the experimenter is familiar with this procedure and that the anesthetic has been tested: A lethal dose of anesthetic administered prior to an oviduct transfer is an unfortunate end to a day spent collecting and microinjecting eggs. The anesthetic described here is Avertin (administered ip); other anesthetics, perhaps routinely used in the experimenter's animal house, may be used.