390 Dr. Marshall Hall on the Act of Vomiting, 



ing, by which, indeed, the contents of the stomach are frequently 

 expelled : the larynx, in the former, is, however, permanently^ 

 — in the latter, only momentarily closed; and there is, doubtless, 

 a different condition of the cardiac orifice and of the oesophagus. 



It appeared to me, from these views of this subject, that, if 

 an opening were made into the trachea, or through the pa- 

 rietes of the thorax, the effort of expiration constituting the 

 act of vomiting, would issue in expelling the air through these 

 orifices respectively, and the evacuation of the stomach would 

 be prevented ;. and I determined to submit the fact to the test 

 of experiment. I took a little dog, made an ample opening 

 into the windpipe, and gave a few grains of the sub-sulphate of 

 mercury. The animal soon became sick. The first efforts to 

 vomit induced a forcible expulsion of air through the orifice 

 in the trachea. These efforts soon became very violent, 

 however, and the stomach at length yielded a part of its con* 

 tents. It was perfectly evident that the violent contractions of 

 the abdominal muscles pressed upon the viscera of the abdomen 

 so as to carry the diaphragm upwards to its fullest extent, and 

 that at this moment vomiting was effected. The act of ex- 

 piration was so forcible, that a lighted candle placed near the 

 tracheal orifice was several times extinguished. In a second 

 experiment, a free opening was made into the thorax between 

 the sixth and seventh ribs of the right side. The lung col- 

 lapsed partially only. During the first efforts to vomit, air was 

 forcibly expelled through this orifice, the lung was brought 

 almost into contact with it, the stomach was not evacuated. 

 But as the efforts to vomit became extreme, a portion of lung 

 was driven through the thoracic opening with violence and a 

 sort of explosion, and at the same instant the stomach yielded 

 its contents. These experiments appear to admit only of one 

 explanation, of one conclusion, — that the act of vomiting is 

 a forcible expiratory effort, the larynx being firmly closed, and 

 the diaphragm perfectly inert. 



It must be regarded as singular that M. Bourdon, by whom 

 the action of the expiratory muscles, in their various " efforts," 

 has been so well investigated*, should have adopted other 

 views of the act of vomiting. 



* Recherches sur le M^chanisme de la Respiration, &c, Par Isid, Bourdon, A 

 Paris, 1820. 



