2 34 DISEASES SECT. XXXIL 2. 2. 



the body is much exhaufted by haemorrhages, or by fatigue, as 

 well as in nervous fevers, the pulfe becomes quick and imall ; 

 and fecondly, in all thofe cafes if an increafe of flimulus be ad- 

 ded, by giving a little wine or opium ; the quick fmall pulfe be- 

 comes flower and larger, as any one may eaGly experience on 

 himfelf, by counting his pulfe after drinking one or two glafTes 

 of wine, when he is faint from hunger or fatigue. 



Now nothing can fo ftrongly evince that this quick fmali 

 pulfe is owing to defet of irritability, as that an additional 

 ftimulus, above what is natural, makes it become flower arid 

 larger immediately ; for what is meant by a defect of irritabili- 

 ty, but that the arteries and heart are not excited into their ufual 

 exertions by their ufual quantity of ftimulus? but if you increafe 

 the quantity of ftimulus and they immediately aft with rheir 

 ufual energy, this proves their previous want of their natural de- 

 gree of irritability. Thus the trembling hands of drunkards in 

 a morning become fteady, and acquire iirength to perform their 

 ufual offices, by the accuftomed ftimulus of a glafs or two of 

 brandy. 



2. In deep and in apoplexy the pulfe becomes flower, which 

 is not owing to defect of irritability, for it is at the fame time 

 larger ; and thence the quantity of the circulation is rather in- 

 creafed than diminifhed. In thefe cafes the organs of fenfe arc 

 clofed, and the voluntary power is fufpended, while the motions 

 dependent on internal irritations, as thofe of digeftion and fecre- 

 tion, are carried on with more than their ufual vigour ; which 

 has led fuperficial obfervers to confound thefe cafes with thofe 

 arifing from want of irritability. Thus if you lift up the eyelid 

 of an apoplectic patient, who is not actually dying, the iris 

 will, as ufual, contract itfelf, as this motion is aflbciated with 

 the ftimulus of light ; but it is not fo in the laft ftages of ner- 

 vous fevers, where the pupil of the eye continues expanded in 

 the broad day light : in the former cafe there is a want, of volun- 

 tary power, in the latter a want of irritability. 



H nee alfo thofe conftitutions which are deficient in quantity 

 of irritability, and which poflefs too great fenfibiiity, as during 

 the pain of hunger, of hyfteric fpafrns, or nervous headachs, are 

 generally fuppofed to have too much irritability ; and opium, 

 which in its due dofe is a mod powerful ftimulant, is errone- 

 oufly called a fedative ; becaufe by increafing the irritative mo- 

 tions it decreafes the pains arifing from defect of them. 



Why the pulfe (hould become quicker both from an increafe 

 of irrigation, as in the fynocha irritativa, or irritative fever with 

 itrong pulfe; and from the decreafe of it, as in the typhus irrita- 

 tivus, or irritative fever with weak pulfe ; feems paradoxical* 



The 



