244 DISEASES SECT. XXXV. i. 2 



modes of action, and endeavour to {hew, that though the pri- 

 mary and fecondary parts of thefe trains or tribes of motion are 

 connected by irritative aflbciation, or their previous habits of 

 ading together, as defcribed in Ser'l. XX. on Vertigo. Yet 

 that their aling with fimilar or diiiimilar degrees of energy, 

 depends on the greater or lefs quantity of fenforial power, which 

 the primary part of the train expends in its exertions. 



The alions of the (lomach conftitute fo important a part of 

 the aflbciations of both irritative and fenfitive motions, that it is 

 faid to fympathize with almoft every part of the body ; the firfl 

 example, which I (hall adduce to fhew that both the primary 

 and fecondary parts of a train of irritative aflbciations of motion 

 at with increafed energy, is taken from the confent of the fkui 

 with this organ. When the aHon of the fibres of the (lomach 

 is increafed, as by the flimulus of a full meal, the exertions of 

 the cutaneous arteries of the face become increafed by their ir- 

 ritative aflbciations with thofe of the ftomach, and a glow or 

 flufhing of the face fucceeds. For the finall veffels of the ikin 

 of the face having been more accuftomed to the varieties of ac- 

 tion, from their frequent expofure to various degrees of cold and 

 heat, become more eafily excited into increafed aciion, than thofe 

 of the covered parts of our bodies, and thus ac~l with more ener- 

 gy from their irritative or fenfitive aflbciations with the ftom- 

 ach. On this account in fmall-pox the eruption in confequence 

 of the previous affection of the ilomach breaks out a day foonej 

 on the face than on the hands, and two days fooner than on the 

 trunk, and recedes in fimilar times after maturation. 



But fecondly, in weaker conftitutions, that is, in thofe who 

 poffefs lefs fenforial power, fo much of it is expended in the in- 

 creafed actions of the fibres of the ftomach excited by the ftimu- 

 iusof a meal, that a fenfe of chilnefs fucceeds inftead of the uni- 

 verfal glow above mentioned ; and thus the fecondary part of 

 the aflbciated train of motions is diminifhed in energy, in con- 

 fequence of the increafed a&ivity of the primary part of it. 



2. Another inftance of a fimilar kind, where the fecondary 

 part of the train a&s with lefs energy in confequence of the 

 greater exertions of the primary part, is the vertigo attending in- 

 toxication ; in this circumftance fo much fenforial power is ex- 

 pended on the ftomach, and on its neareft or more ftrongly aflb- 

 ciated motions, as thofe of the fubcutaneous veflels, and proba- 

 bly of the membranes of fome internal vifcera, that the irritative 

 motions of the retina become imperfeUy exerted from defi- 

 ciency of fenforial power, as explained in Sed. XX. and XXL 

 3. on Vertigo and on Drunkennefs, and hence the Daggering ine- 

 briate cannot completely balance himfelf by fuchindiftincT; vifion. 



q. An 



