SECT. XIV. 7. PRODUCTION OF IDEAS. 131 



tract, and exclude their contents, and many other 

 ynufcles by affociation act along with them ; but if 

 thefe evacuations are not foon complied with, pain 

 is produced by a little further extenfion of the 

 mufcular fibres : a fimilar pain is caufed in the 

 ynufcles, when a limb is much extended for the 

 reduction of diflocated bones ; and in the punifli- 

 ment of the rack : and in the painful cramps of the 

 calf of the leg, or of other mufcles, for a greater 

 degree of contraction of a mufcle, than the move- 

 ment of the two bones, to which its ends are af- 

 fixed, will admit of, muft give fimilar pain to 

 that, which is produced by extending it beyond 

 its due length. And the pain from punctures or 

 incifions arifes from the diftention of the fibres, as 

 the knife pafles through them ; for it nearly ceafes 

 as foon as the divifion is completed. 



All thefe motions of the mufcles, that are thus' 

 paturally excited by the flimulus of diftending bo- 

 dies, are alfo liable to be called into ftrong action 

 by their catenation, with the irritations or fenfa- 

 tions produced by the momentum of the progref- 

 five particles of blood in the arteries, as in inflam* 

 matory fevers, or by acrid fubftances on other fen- 

 fible organs, as in the ftrangury, or tenefmus, or 

 cholera. 



We mall conclude this account of the fenfe of 

 extenfion by obferving, that the want of its object 

 is attended with a difagreeable fenfation, as well as 

 the excefs of it. In thofe hollow mufcles, which 

 have been accuftomed to it, this difagreeable fenfa- 

 tion is called faintnefs, emptinefs, and finking; 

 ^nd, 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 tapping 

 in the dropfy. 



VIII, 



