DEGLUTITION. 205 



was empty ; though during digestion, the contractions were 

 frequent in proportion to the quantity of food in the 

 stomach. The contraction was always increased by press- 

 ing the stomach and attempting to pass some of its contents 

 into the oesophagus. 1 This provision is undoubtedly im- 

 portant in preventing regurgitation of the contents of the 

 stomach, especially when the organ is exposed to pressure, as 

 in urination or defecation. We have already noted the 

 action of the crura of the diaphragm, which have a tendency 

 to close the oesophageal opening during inspiration. 2 



The length of time occupied in the third period of deglu- 

 tition was noted by Magendie in the inferior animals, but we 

 have been unable to find any definite observations on this 

 point in the human subject ; though this would have been 

 easy in the cases of gastric fistula which, from time to time, 

 have come under the observation of physiologists. Magendie 

 found that the alimentary bolus sometimes occupied two or 

 three minutes in its passage, and that it was often momenta- 

 rily arrested in its course. It frequently seems as though we 

 were ourselves cbnscious of a very slow passage of food down 

 the oesophagus, and not infrequently a piece of bread or a 

 mouthful of liquid is taken to hasten it ; but it is not prob- 

 able that every alimentary bolus remains for two or three 

 minutes in the oesophagus, and liquids undoubtedly are 

 swallowed with considerable rapidity, as they can soon be 

 recognized in the stomach by their temperature. As the 

 lower part of the oesophagus is composed chiefly of un- 

 striped muscular fibres, it is probable that here the contrac- 

 tions are more gradual than in the upper portions. 



As we have already had occasion to remark, the muscular 

 movements which take place during all the periods of deglu- 

 tition are peculiar. The first act is generally involuntary from 



1 MAGENDIE, Memoire sur VCEsophage, lu d Vlnstitut de France, le 11 octo- 

 bre, 1813. 



2 See Tol. i., Respiration, p. 370. 



