CHAP. XXIV.] VOMITING. 215 



muscles and to excite to simultaneous and combined action some 

 which usually antagonise each other, and are, therefore, never, 

 excepting in this act, in the same condition at the same time. 

 We allude to the abdominal muscles and the diaphragm; the 

 former as muscles of expiration being the habitual antagonists of 

 the latter, which is the great muscle of inspiration. In short, 

 the excitation of the nervous centre, which is sufficient to cause 

 vomiting, gives rise to a forcible act of respiration, in which the 

 act of expiration is so powerfully opposed by the contracted state 

 of the constrictors of the larynx, the diaphragm also remaining in 

 strong contraction, that the main force of the expiratory muscles 

 is directed to compress the stomach against the latter muscle. 



On the subjects of this chapter see the various works on Anatomy, and the 

 principal system of Physiology previously referred to ; (Euvres de Spallanzani ; 

 Tiedemann et Gmelin sur la Digestion : Hunter's Animal (Economy, by Owen ; 

 Eberle, Physiologic der Verdauung, 1834 ; Simon's Chemistry, by Day ; Dumas, 

 Trait6 de Chimie,tom. viii. (1846); Beaumont on Digestion; Blondlot sur la 

 Digestion ; Dr.Kirkes' excellent Manual of Physiology ; BouchardatandSandras, 

 Comptes Rendus for 1844 ; Bernard and Barreswil, Comptes Rendus, 1844 ; 

 Dr.R. D. Thomson, Lon. Med. Gaz. 1845. 



