fikcT. XXXIII. i, $. OF SENSATION. 30$ 



to external objects, neither of which exifts in the delirium of 

 levers or in dreams. 



5. It would appear, that the vafcular fyftems of other animals 

 are left liable to be put into action by their general furn of 

 pleafurable or painful fenfation ; and that the trains of their 

 ideas, and the mufcular motions ufualiy aflbciated with them, 

 are lets powerfully connected than in the human fyftem. For 

 other animals neither weep, nor fmile, nor laugh ; and are 

 hence feldom iubiecl to delirium, as treated of in Sect. XVI. on 

 Inftin£r. Now as cur epidemic and contagious diieaies arc 

 probably produced by difagreeable fenfation, and not {imply by 

 irritation ; there appears a reafon why brute animals are icis 

 liable to epidemic or contagious difeafes ; andfecondly, why 

 none of our contagions, as the.fmall-pox or meafles, can be com- 

 municated to them, though one of theirs, viz. the hydrophobia, 

 •as well as many of their poifons, as thofe of makes and of in- 

 fects, communicate their deleterous or painful effects to mankind. 



Where the quantity of general painful fenfation is too great 

 in the fyftem, inordinate voluntary exertions are produced either 

 of our ideas, as in melancholy and madnefs, or of our mufci^ 

 as in convulfion. From theie maladies alio brute animals are 

 much more exempt than mankind, owing to their greater inapti- 

 tude to voluntary exertion, as mentionedin Sect. XVI. onLifdnct. 



II. 1. When any moving organ is excited into fuch violent 

 motions, that a quantity of pleafurable or painful fenfation is 

 produced, it frequently happens (but not always) that new mo- 

 tions of the affected organ are generated in confequence of the 

 pain or pleafure, which are termed inflammation. 



Thefe new motions are of a peculiar kind, tending to diftend 

 the old, and to produce new fibres, and thence to elongate the 

 ftraight mufcles, which ferve locomotion, and to form new vef- 

 fels at the extremities or fides of the vafcular mufcles. 



2. Thus the pleafurable fenfations produce an enlargement of 

 the nipples of nurfes, of the papilke of the tongue, of the peni>j 

 and probably produce the growth of the body from its embryon 

 ftate to its maturity •, whilft the new motions in confequence of 

 painful fenfation, with the growth of the fibres or vellels, which 

 they occafion, are termed inflammation. 



Hence when the ftraight mufcles are inflamed, part of their 

 tendons at each extremity gain new life and fenfibility, and thus 

 the mufcle is for a time elongated ; and inflamed bones become 

 foft, vafcular, and fenfible. Thus new veiTels fhoot over the 

 ■cornea of inflamed eyes, and into fcirrhous tumours, when thev 

 become inflamed ; and hence all inflamed parts grow together 

 Iby intermixture, and inoculation of the new and old veflel;. 



The 



