I 277 ] 
ful as when made by a large vein j and 
that it is fometimes even ufeful,as has been 
obferved by fome practitioners, among 
whom we may count Ramazzini. An 
evacution made from a large vein is fre¬ 
quently followed by faintnefs and fwoon- 
ing, fymptoms which announce a change 
in the nervous fylfem, and which does not 
happen when the blood is taken from 
fmaller veffels. It is to this change that 
the bad confequences are owing. And 
this, if I am not miftaken, is the reafon 
why perfons who have been attacked by 
the plague in certain cafes, have expired 
immediately after having’ been bled in the 
arm, or during the operation. 
But thefe diforders themfelves, and very 
adtive medicines, may fometimes give rife 
to fuch a favourable revolution in the 
fyftem, as to bring back the aCtion of 
health. Many perfons are in this way 
cured of periodical fevers, and of other 
T 3 difeafes, 
