t =8 Si 
Hikewife their regular periods and duration* 
Van Swieten gives the hiftory of a girl, 
who, when in perfect health, was fright¬ 
ened at the fight of a fquirrel, and feized 
with a quartan ague. She was cured of it; 
but by feeing a dead fquirrel was again 
attacked by a return of it. The Abderites 
were all taken ill of a fever, when the 
celebrated tragedian Archelaus reprefented 
the fable of Andromeda, and all were re¬ 
covered of it on the feventh day. 
When a difeafe ceafes after having run 
through its ordinary courfe, it does not 
ceafe becaufe the miafma has loft its 
power, but becaufe the nervous fyftem is 
no longer fenfible of its impreffion, or 
becaufe the morbific impreffion made upon 
the brain ceafes of itfelf. This propo- 
fition may be confidered a confequence of 
the foregoing fadts and cafes. 
That a convalefcent retains within him 
the feeds of the diforder from which he 
has 
