SECT. XXV. 6. STOMACH AND INTESTINES. 323 



ufual, all their motions, and thofe of the glands 

 and lymphatics, are itimu'ared into ftronger action 

 than ufual, and perform their offices with greater 

 vigour and in lefs time : Inch are the effects cf 

 certain quantities of fpice or oi vinous fpirit. 



6. But if the quantity or duration of thefe (timuii 

 are Mill further increased, the ftomach and throat 

 are (iimulated into a motion, whole direction is 

 contrary to the natural one above defcribed ; and 

 they regurgitate the materials, which they contain, 

 iinltead of carrying them forwards. This retrograde 

 motion of the (tomach may be compared to the 

 firetchings of wearied limbs the contrary wav, and 

 is well elucidated by the following experiment. 

 Look earneftly for a minute or two on an area an 

 inch Iquare of pink (ilk, placed in a ilrong light, 

 the eye becomes fatigued, the colour becomes faint, 

 and at length vaniihes, for the fatigued eye can no 

 longer be itimulated into, direct motions ; then on 

 doling the eye a green fpeclrum will appear in it, 

 which is a colour directly contrary to pink, and 

 which will appear and difappear repeatedly, like the 

 efforts in vomiting. See Section XXIX i r. 



Hence all thole drugs* which by their bitter or 

 aftringent (timulus increale the action of the 

 ftomach, as camomile and white vitriol, if their 

 quantity is increafed above a certain dole, become 

 emetics. 



Thefe inverted motions of the ftomach and throat 

 are generally produced from the fiimulus of unna- 

 tural food, and are attended with the Jenfation of 

 naufea or ficknefs : but as this fenfation is again 

 connected with an idea of the diftafteful food, 

 which induced it ; fo an idea of nauleous food will 

 alfo fometimes excite the action of naufea ; and that 

 give rife by affociation to the inverfion of the moti- 

 ons of the itomach and throat. As fome, who 

 have had horfe-flefh or dogs-fielh given them for 



beef 





