44 



the pharynx, is the (Esophagus or gullet, a cylindrical 

 tube lying near the back-bone in the chest, and termi- 

 nating in the stomach. Now, when a morsel of food is 

 ready to be swallowed, it is placed on the superior sur- 

 face of the tongue which is then closely applied to the 

 arch of the palate. The muscles strongly contracting on 

 the food, it is necessarily directed backward, this being 

 the only direction in which it can escape from the sur- 

 rounding pressure. Having now reached the pharynx, 

 contrivances are obviously required to prevent it from 

 falling into any of those apertures which open into that 

 cavity, except the right one. The veil of the palate, 

 therefore, being drawn- back by its muscles, is applied 

 like a valve over the aperture leading to the nasal fossa? 

 and Eustachian tubes, and thus the morsel is effectually 

 prevented from passing into either of them. 



Emily. It does pass through, sometimes, notwith- 

 standing all these obstacles, for it happened to myself 

 this morning while eating my breakfast, filling my eyes 

 with tears, though but the instant before I was heartily 

 laughing: 



Dr. B. And for this very reason was it, for when we 

 are coughing or laughing, and swallowing at the same 

 lime, the air rushing up from the lungs through the chink 

 of the glottis, pushes the food along towards the nasal 

 fossae with considerable force. 



Emily. It is prevented from entering the wind-pipe, 

 I suppose, by the epiglottis shutting down, and permit- 

 ting the food to pass safely over it, as upon a bridge. 

 How admirably this object is effected by this beautiful 

 contrivance ! 



Dr. B. Withhold your admiration a moment, till 

 you are certain that the cause of it actually exists, 

 ^our explanation was the one generally given, until it 

 was proved a few years ago, by Majendie, the distin- 

 guished French physiologist, to be inadequate for the 

 purpose. That the epiglottis shuts down as you have 

 Imagined, is undoubtedly true; but Majendie cutoff the 



