So6 DISEASES OF ASSOCIATION. SECT. XXXV. i; 



deduced j when an emetic medicine is adminiflered, 

 it produces the pain of ficknefs, as a difagreeable 

 tafte in the mouth produces the pain of naufea ; 

 thefe patns, like thofe of hunger, or of cold, or 

 like thofe, which are ufually termed nervous, as the 

 head r ach or hemicrama, do not excite the organ in- 

 to greater aclion ; but in this cafe I imagine the 

 pains of ficknefs or of naufea counteracl or deflroy 

 the pleafurable fenfation. which feems neceffary to 

 digeition, as fhewn in Sett. XXXIII. i. f. The pe- 

 riftaltic motions of the fibres of the ftomach be- 

 come enfeebled by the \vant of this ilimulus of 

 pleafurable fenfation, and in confequence flop for a 

 time, and then become inverted ; for they cannot 

 become inverted without being previoufly flopped. 

 Now that this inverfion of the trains of motion of 

 the fibres of the ftomach is owing to the deficiency . 

 of pleafurable fenfation is evinced from this circum- 

 fiance, that a naufeous idea excited by words wilt 

 produce vomiting as effectually as a naufeotis drug. 



Hence it appears, that the act of naufea or vo* 

 miting expends lefs fenforial power than the ufual 

 periflaltic motions of the ftomach in the digeftion 

 of our aliment ; and that hence there is a greater 

 quantity of fenforial power becomes accumulated 

 in the fibres of the flomach, and more of it in 

 confequence to fpare for the action of thofe parts 

 of the fyftem, which are thus affociated with the 

 ilomach, as of the whole abforbent feries of veflels, 

 and which are at the fame time excited by their 

 ufual flimuli. 



From this we can underftand, how after the ope- 

 ration of an emetic the flomach becomes more irri- 

 table and fenfible to the ftimulus, and the pleafure 

 of food ; fince as the fenforial power becomes ac- 

 cumulated during the naufea and vomiting, the 

 digeftive power is afterwards exerted more forcibly 

 for a time. It mould, however, be here remarked, 



that 



