Peristalsis consists of a travelling wave of contraction of the circular and longitudinal layers of muscle in the gut wall such that material inside the gut is moved along. The pharmacology of this system has been investigated in isolated trout intestine demonstrating that an intrinsic nerve network exists to control peristalsis; i.e., cholinergic drugs stimulated and adrenergic drugs inhibited peristaltic movements. The oesophagus arid stomach are also innervated extrinsically by branches of the vagal (cranial X) nerve. No studies appear to have been made so far concerning details of food transport through the teleost gut except for measurements of gastric evacuation time and total food passage time, although gut stasis has been hypothesized to occur in the Pacific salmon, as in domestic animals.