VOMITING. SOT 



plished chiefly by contractions of the stomach and oesopha- 

 gus. It is generally accompanied or preceded by sensible 

 convulsive movements of the oesophagus, involving, possibly, 

 contractions of its longitudinal fibres, which would favor re- 

 laxation of the cardiac opening. Though usually involun- 

 tary, this act is sometimes under the control of the will. 

 When it occurs, while it is difficult or impossible to prevent 

 the discharge of the gas, the accompanying sound may be 

 readily suppressed. Eructation is frequently a matter of 

 habit, which in many persons becomes so developed by prac- 

 tice, that the act may be performed voluntarily at any time. 



