DEGLUTITION. 195 



were, moulded over the glottis. With, the parts removed from 

 the human subject or from one of the inferior animals, we 

 can imitate the natural movements of the tongue and larynx, 

 and it is evident that this provision alone must be sufficient 

 to protect the larynx from the entrance of solid or semi-solid 

 particles of food ; particularly when we remember how the 

 alimentary particles are agglutinated by the saliva, and how 

 easy their passage becomes over the membrane coated with 

 a slimy mucus. Experiments on the inferior animals and 

 observations upon the human subject have conclusively set- 

 tled the question that the deglutition of all articles, except 

 liquids, is generally effected without difficulty, when the epi- 

 glottis has been removed or lost by accident or disease. The 

 same is true when, in addition, the intrinsic muscles of the 

 larynx have been paralyzed by the section of nerves, or even 

 when closure of the rima glottidis is forcibly prevented. It 

 has been shown, however, by the experiments of Longet, that 

 when the larynx is in part prevented from performing its 

 movement of ascension, the deglutition of a moist mass of 

 alimentary matter is effected with difficulty and is followed 

 by a sharp cough ; indicating the entrance of a certain quan- 

 tity of foreign matter into the air-passages. 1 



It is impossible for the muscles of the pharynx to con- 

 tract without drawing together the sides of the larynx, to 

 which they are attached, and assisting to close the glottis. 

 At the same time, as the movements of respiration are ar- 

 rested during deglutition, the lips of the glottis fall to- 

 gether ; as they always do except in inspiration. This fact 

 we have repeatedly observed in demonstrating the respira- 

 tory movements of the glottis; for when the larynx is 

 thus exposed, the animal makes frequent efforts at degluti- 

 tion. In addition to this passive and incomplete approxi- 

 mation of the vocal cords, it has repeatedly been observed 

 that the lips of the glottis are accurately and firmly closed 

 during each act of deglutition. This fact was first actually 



1 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 112. 



