222 DIGESTION. 



does not take place until this is already in contact with the tracheal or bronchial mucous 

 membrane." These experiments strikingly illustrate the conservative function of the 

 acute sensibility of the mucous membrane above the glottis. No foreign substance can 

 find its way into the air-passages by simply dropping into the cavity situated above the 

 vocal cords when respiration is interrupted, but can only enter by being drawn in forcibly 

 and suddenly with an act of inspiration, when the glottis is widely opened. It is now 

 well known to the practical physician that direct applications cannot be made to the in- 

 terior of the larynx, unless an instrument be suddenly introduced with the inspiratory act ; 

 and, at this time, a little dexterity will enable an operator to introduce bodies of consider- 

 able size below the vocal chords. 



Before the experiments of Magendie, in 1813, physiologists were generally of the 

 opinion, judging from anatomical relations, that the epiglottis had the function of pro- 

 tecting the larynx from the entrance of particles of food during the second period of deg- 

 lutition. Magendie extirpated the entire epiglottis in dogs and found that the animals 

 swallowed liquids and solids without difficulty, the act being very seldom followed by 

 cough. The observations on deglutition were made an hour after the removal of the 

 epiglottis. In other animals, the superior and inferior laryngeal nerves were divided, 

 thus paralyzing the muscles of the glottis. The deglutition of liquids especially be- 

 came difficult and was followed generally by cough. As the result of these observations, 

 Magendie came to the conclusion that the larynx is protected during deglutition by clos- 

 ure of the glottis itself. 



Although the experiments on animals were apparently conclusive, observations on 

 the human subject have been cited, in which, after destruction of the epiglottis by dis- 

 ease, there existed persistent difficulty in swallowing liquids. As numerous pathological 

 observations of this character have been reported, the question could not be regarded as 

 entirely settled by the researches of Magendie. It was with the view of determining 

 this more rigorously, that farther experiments were instituted in 1841, by Longet. 



In investigating this question, Longet removed the epiglottis from six dogs. He found 

 that, in the animals kept until the parts were perfectly cicatrized, more or less cough 

 followed the deglutition of liquids. One of these he kept for six months and found that 

 when he drank milk or water cough never failed to follow. The same fact was noted in 

 three of the animals that were killed on the nineteenth day and in one that was killed 

 on the thirtieth day. In all, the complete excision of the epiglottis was verified by post- 

 mortem examination. In one of the animals, killed two days after the operation, that 

 generally swallowed liquids without coughing, there was found a swelling at the base of 

 the tongue which projected over the larynx. 



Several cases of loss of the epiglottis in the human subject are quoted by Longet in 

 support of his view that this part is necessary to the complete protection of the air-pas- 

 sages, particularly in the deglutition of liquids. Two of the most striking of these cases 

 were observed by Larrey, in Egypt. One of these was the case of General Murat, who 

 was wounded by a ball passing through the neck from one angle of the jaw to the other, 

 cutting off the epiglottis, which was expelled by the mouth. In this instance, the diffi- 

 culty in the deglutition of liquids was so great, that it became necessary to introduce 

 them through a tube passed into the oesophagus. In the other case, the epiglottis was 

 entirely removed by a wound and was preserved and presented to the surgeon. In 

 this instance, the difficulty in the deglutition of liquids was even greater than in the 

 former; each effort at swallowing being followed by convulsive and suffocating cough. 

 This difficulty persisted after the parts had become completely cicatrized. In these cases, 

 it is possible that the injury to muscles and other parts from such severe wounds might 

 interfere with the movements of the larynx or the closure of the glottis and thus disturb 

 deglutition. In a case in which the epiglottis had entirely sloughed away as a conse- 

 quence of syphilitic disease, observed by Dr. Austin Flint, the difficulty in swallowing 

 liquids, although sufficiently well marked, was by no means so great as in the cases men- 



