Sect. XIV. 8- OF IDEAS. - 93 



or fenfations produced by the momentum of the progrefTrve par- 

 ticles of blood in the arteries, as in inflammatory fevers, or by 

 acrid fubftances on other fenfible organs, as in the flrangury, or 

 tenefmus, or cholera. 



We fliall conclude this account of the fenfe of extenfion by 

 obferving, that the want of its object is attended with a difagree- 

 able fenfation, as well as the excels of it. In thofe hollow muf- 

 cles, which have been accuftomed to it, this difagreeable fenfa- 

 tion is called faintnefs, emptinefs, and finking ; and, when it 

 arifes to a certain degree, is attended with fyncope, or a total 

 quiefcence of all motions, but the internal irritative ones, as 

 happens from fudden lofs of blood, or in the operation of tap- 

 ping in the dropfy. 



VIII. Of the Appetites of Hunger •, Thirf, Heat, Extenfion , the 10 ant 

 of Frefh Air, Animal Love, and the Suckling of Children. 



Hunger is moil probably perceived by thofe numerous rami- 

 fications of nerves that are fcen about the upper opening of the 

 ftomach ; and thirft by the nerves about the fauces, and the top 

 of the gula. The ideas of thefe fenfes are few in the generality 

 of mankind, but are more numerous in thofe, who by difeafe, or 

 indulgence, defire particular kinds of foods or liquids. 



A fenfe of heat has already been fpoken of, which may with 

 propriety be called an appetite, as we painfully defire it, when it 

 is deficient in quantity. 



The fenfe of extenfion may be ranked amongfl thefe appe- 

 tites, fince the deficiency of its object, gives difagreeable fenfa- 

 tion ; when this happens in the arterial fyftem, it is called faint- 

 nefs, and feems to bear fome analogy to hunger and to cold ; 

 which like it are attended with emptinefs of a part of the vafcu- 

 lar fyftem. 



The fenfe of want of frefh air has not been attended to, but 

 is as diftinct as the others, and the firft perhaps that we experi- 

 ence after our nativity \ from the want of the object, of this 

 fenfe many difeafes are produced, as the jail-fever, plague, and 

 other epidemic maladies. Animal love is another appetite, 

 which occurs later -in life, and the females of lactiferous animals 

 have another natural inlet of pleafure or pain from the fuckling 

 their offspring. The want of which, either owing to the death 

 of their progeny, or to the fafhion of their country, has been fa- 

 tal to many of the fex. The males have alfo pectoral glands, 

 which are frequently turgid with a thin milk at their nativity, 

 and are furnifhed with nipples, which erect on titillation like 

 thofe of the female j but which feem now to be of no further 



ufc, 



