fee*. XXXVI. 2. i. OF DISEASES. 353 



into ftronger action by the ftimulus of a lefs degree of Heat, 

 than would previoufly have produced that effect. 



From hence the periods of fome fever-fits may take their ori- 

 gin, either (imply, or by their accidental coincidence with lunar 

 and folar periods, or with the diurnal periods of heat and cold, 

 to be treated of below ; for during the cold fit at the commence- 

 ment of a fever, from whatever caufe that cold fit may have 

 been induced, it follows, 1. That the fpirit of animation muft 

 become accumulated in the parts, which exert during this cold 

 fit lefs than their natural quantity of action. 2. If the caufe 

 producing the cold fit does not increafe, or becomes diminifhed ; 

 the parts before benumbed or inactive become now excitable by 

 fmaller ftimulus, and are thence thrown into more violent ac- 

 tion than is natural *, that is a hot fit fucceeds the cold one. 3. 

 By the energetic action of the fyllem during the hot fit, if it 

 continues long, an exhauftion of the fpirit of animation takes 

 place ; and another cold fit is liable to fucceed, from the moving 

 fyftem not being excitable into action from its ufual ftimulus. 

 This inirritability of the fyftem from a too great previous ftimu- 

 lus, and confequent exhauftion of fenforial power, is the caufe of 

 the general debility, and ficknefs, and head-ach, fome hours af- 

 ter intoxication. And hence we fee one of the caufes of the 

 periods of fever-fits ; which however are frequently combined 

 with the periods of our diurnal habits, or of heat and cold,, or of 

 folar or lunar periods. 



When befides the tendency to quiefcence occafioned by the 

 expenditure of fenforial power during the hot fit of fever, fome 

 other caufe of torpor, as the folar or lunar periods, is neceffary 

 to the introduction of a fecond cold fit ; the fever becomes of 

 the intermittent kind 5 that is, there is a fpace of time intervenes 

 between the end of the hot fit, and the commencement of the 

 next cold one. But where no exterior caufe is neceflary to the 

 introduction of the fecond cold fit ; no fuch interval of health 

 intervenes j but the fecond cold fit comrrlences, as foon as the 

 fenforial power is fumciently exhaufted by the hot fit ; and the 

 fever becomes continual. 



II. 1. The following are natural animal actions, which are 

 frequently catenated with our daily habits of life, as well as ex- 

 cited by their natural irritations. The periods of hunger and 

 third become catenated with certain portions of time, or degrees 

 of exhauftion, or other diurnal habits of life. And if the pain 

 of hunger be not relieved by taking food at the ufual time, it is 

 liable to ceafe till the next period of time or other habits recur j 

 this is not only true in refpect to our general defire of food, but 

 the kinds of it alfo are governed by this periodical habit ; info- 



Vol. I. X x much* 



