VOMITING. /r>l 



the human subject. Several instances are recorded in which, 

 either under the control of the will or involuntarily, food is 

 returned to the mouth after a meal. 



All the persons who have referred to the subject of the 

 difficulty of vomiting in the horse, have overlooked, to a great 

 extent, the point which my brother has justly insisted on, 

 that the emesis, or the tendency to vomiting, is not readily 

 excited in this animal. Nevertheless there are cases in 

 which it is observed, and vomiting is possible. These are, 

 1st, Cases of inordinate distention of the stomach; 2ndly, 

 Cases of dilatation of the lower end of the oesophagus ; Srdly, 

 Cases of obstruction to the pylorus; 4thly, Ruptures of the 

 stomach; 5thly, Hering refers to cases of vomiting due to 

 ulceration of the mucous membrane of the stomach. 



The mechanical impediments to vomiting, insisted on by 

 many physiologists, with the exception of two, and which are 

 the disadvantageous direction of the oesophagus into the 

 stomach, and the tendency of the mucous membrane to fold 

 on itself and plug the cardiac orifice, are all false. 



Many have described a spiral valve at the cardiac opening 

 of the stomach, and I here reproduce a drawing of it from 

 Leyh's Anatomy, but no such valve exists. It is simply a 



Fig. 78. 



