284 DISEASES Sect. XXXII. 2. 2. 



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

 well as in nervous fevers, the pulfe becomes quick and fmall 5 

 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 eafily experience on 

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

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



Now nothing can fo flrongly evince that this quick fmall 

 pulfe is owing to defecl: of irritability, as that an additional 

 ftimulus, abov« what is natural, makes it become flower and 

 larger immediately : for what is meant by a defecl: 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 act with their 

 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 ftrength to perform their 

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

 brandy, 



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

 Lo not owing to defecl 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 are 

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

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

 tion, arc 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 alfociated 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. 



Hence alfo thofe conftitutions which are deficient in quantity 

 of irritability, and which pofiefs too great fenfibility, as during 

 the pain of hunger, of hyiteric fpafms, or nervous headachs, are 

 generally fuppofed to have too much irritability ; and opium, 

 which in its due dole is a moft powerful ftimulant, is errone- 

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

 ms it decreases the pains arifing from defect of them. 

 Why the pulfe (hpuld become quicker both from an increafe 

 F irritation, as in the fynocha irritativa, or irritative fever with 

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

 U6, or irritative fever with weak pulfe ; feems paradoxical. 



The 



