DIGESTIVE APPARATUS. 151 



Trauniatic inflammation of the stomach and dia- 

 phragm. 



[All cachectic diseases.] 



[Many cerebral diseases.] 

 Eructation or belching occurs normally fct ruminants 

 only. This consists in audible expulsion of paunch gases 

 through the oesophagus and mouth. [Eructations become 

 distinctly audible and abnormally frequent during fermentation 

 processes in the paunch, slight tympanitis, etc. Sometimes 

 they are accompanied by disagreeable odors (fermentations) 

 but the character of the food also plays a role here (onions).] 



V. Vomiting. 



Vomiting is a reflex (involuntary) spasmodic evacua- 

 tion of the stomach or paunch contents through the mouth 

 or nasal passages. This act is assisted by simultaneous con- 

 traction of the abdominal and inspiratory muscles. Imme- 

 diately preceding the act of vomiting animals make a deep 

 inspiratory movement. Vomiting is caused by indirect 

 (rarely direct) stimulation of the vomiting center in the 

 medulla oblongata. 



The ease with which vomiting occurs in our domestic 

 animals varies with the species according to the anatomical 

 construction and the degree of fullness of the stomach. Car- 

 nivora, pigs, and birds vomit most readily and with greatest 

 ease, ruminants less so. Horses rarely vomit. This is ex- 

 plained by the anatomical structure and position of the stom- 

 ach. [The stomach of the horse is comparatively small and 

 even when filled does not always come, into contact with the 

 floor of the abdomen, hence is not easily affected by abdom- 

 inal contractions.] 



Further, the spiral arrangement of the muscular coats, 

 insertion of the esophagus at the middle of the stomach, its 

 contracted and thickened wall at the point of insertion (in 

 contrast to the funnel shaped thin walled structure of this 



