Caenorhabditis elegans spends most of its life feeding. When feeding, it moves only short distances but intestinal contents are moved to and fro and thus mixed. The nematodes also defaecate and lay eggs during the feeding phase in bacterial culture. Defaecation is one of a series of events which causes the forward and backward movement of intestinal contents. These rhythmic movements, once initiated, appear to be controlled by a pacemaker and are unrelated to feeding rates. Oviposition is associated with movements of the genital tract and it can occur at any posture and does not influence the rate of other activities. After food-deprivation, C. elegans shows no measureable hunger response on being returned to bacteria. Experiments with excised parts of worms showed that isolated anterior ends will feed both in and out of bacteria and move forward and backward. Isolated posterior halves without a pharynx or circumpharyngeal commissure will lay eggs and defaecate.