344 DISEASES Skct. XXXV. u z; 



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

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

 connected by irritative ailoeiation, or their previous habits of 

 acting together, as defcribed in Seel:. XX. on Vertigo. Yet 

 that their acting with fimilar or difhmilar degrees of energy, 

 depends on die greater or lefs quantity of fenforial power, whi< 

 the primary part of the train expends in its exertions. 



The actions of the itomach conftitiue fo important a part of 

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

 faid to fympathize with almoft every part of the body ; the fir ft 

 example, which I fhall adduce to mew that both the primary 

 and fecondary parts of a train of irritative afTociations of motion 

 act with increafed energy, is taken from the confent of the fkiii 

 with this organ. When the action of the fibres of the ftomach 

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

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

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

 flushing of the face fucceeds. For the fmall veflels of the fkin 

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

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

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

 of the covered parts of our bodies, and thus act with more ener- 

 gy from their irritative or fenfitive aflbciations with the ftom- 

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

 of the previous affection of the ftomach breaks out a day fooner 

 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 

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

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

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

 versal glow above mentioned; and thus the fecondary part of 

 the afTociated train of motions is diminifhed in energy, in conie- 

 cuence of the increafed activity of the primary part of it. 



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

 part of the train acts with lets 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 nearelt or more ftrongly afTo- 

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

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

 motions of the retina become imperfectly exerted from defi- 

 ciency of fenforial power, as explained in Sect. XX. and XXI. 

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

 briate cannot completely balance himfclf by fuch indiilinct vifion. 



3- A 



