Skcr. XVill. 15. OF SLEEP. 251 



other mufcles are, by their antagonids, but by the 

 weight of' the whole body on the balls of the toes ; 

 and that weight applied to great mechanical advan- 

 tage on the heel, that is, on the other end of the 

 bone of the foot, which thus acts as a lever. 



Another difeafe, the periods of which generally 

 commence during our fleep, is the a'thma. What- 

 ever may be the remote caufe of paroxyfms of afth- 

 ma, the immediate caufe of the convulfive refpira- 

 tion, whether in the common ai^hina, or in what is 

 termed the convulfive afthma, which are perhaps 

 only different degrees of ihe fame difeafe, mud be 

 owing to violent voluntary exertions to relieve pain, 

 as in other corivulfions ; and the increafe of irrita- 

 bility to internal flimuii, or of fenfibility, during 

 Deep mud occafion them to commence at this time. 



Debilitated people, who have been unfortunately 

 accuftomed to great ingurgitation of fpirituous po- 

 tation, frequently part with a great quantity of 

 water during the night, but with not more than ufual 

 in the day-time. This is owing to a beginning tor- 

 por of the abforbent fyftem, and precedes anafarca, 

 which commences in the day, but is cured in the 

 night by the increafe of the irritability of the abfor- 

 bent fyliem during ileep, which thus imbibes from 

 the cellular membrane the fluids, which had been 

 accumulated there during the day ; though it is pof- 

 fible the horizontal pofition of the body may con- 

 tribute fomething to this purpofe, and alfo the 

 greater irritability of fome branches of the abforbent 

 veflels, which open their mouths in the cells of the 

 cellular membrane, than that of other branches. 



As foon as a perfon begins to ileep, the irritability 

 and fenfibility of the fyltern begins to increafe, 

 owing to the fufpenfionof volition and the exclufion 

 of external ftimuli. Hence the actions of the veflels 

 in obedience to internal Simulation become ftronger 

 and more energetic, though lefs frequent in refpecl: 

 to number. And as many of the fecretion$ are in. 

 VOL. I, .S creafed 



