PHYSICAL AND LITERARY. 497 



diminution of the fenfibility of this or- 

 gan. 



$. In time of lleep, as the exercife of 

 the leveral fenfes is either fufpended or 

 inuch impaired ; fo the fenfibility or feel- 

 ing, with which the organs of the body 

 are more or lefs endued, feems to be ren- 

 dered lefs acute. Thus we feel ourfelves 

 afFedled with a kind of flupor, when we 

 are juft falling afleep, and are then infen- 

 fible of lefTer ftimuli. The thin rheumy 

 ■which, by irritating the windpipe, keeps 

 us almoft perpetually coughing when a- 

 i^ake, gives us little or no difturbance id 

 fleep ; any extraordinary flimulus in the 

 guts is alfo lefs perceived then ; and hence 

 it is, that a dofe of any purgative taken 

 at night, is much longer before it ope- 

 rates, than when it is fwallowed in the 

 morning. If the heart, therefore, like the 

 other organs of the body, becomes lefs 

 fenfible or irritable in time of fleep, it will 

 not be fo quickly excited into corltrac- 

 tion as ufual, by the venous blood rufh-*- 

 ing into its cavities ; and hence its con- 



Yo L. I. R r r tra(^ions 



