25 
of the Heart and Arteries. 
to a morbid extent, may also be a principal cause of another 
general derangement of the circulation, the motion of the blood 
being accelerated, and the arteries emptied, so that the pulse 
may be small and weak, while the veins are overcharged, and 
the heart exhausted by violent and fruitless efforts to restore 
the equilibrium ; and this state appears to resemble, in many 
respects, the affections observed in typhus. When, on the 
contrary, the capillary vessels are contracted, the arteries are 
again distended, although without the excess of heat which 
must attend their distension from an increased action of the 
heart, and possibly without fever : an instance of this appears 
to be exhibited in the shrinking of the skin, which is frequently 
observable from the effect of cold, and in the first impression 
produced by a cold bath : nor is it impossible, that such a con- 
traction may exist in the cold fit of an intermittent, although 
it seems more probable that a debility of the heart is the pri- 
mary cause of this affection. 
Besides these general causes of derangement, which appear 
to be more or less concerned in different kinds of fever, there 
are other more partial ones, which seem to have a similar re- 
lation to local inflammations. The most obvious of these 
changes are such as must be produced by partial dilatations 
or contractions of the capillary vessels ; since, as I have en- 
deavoured to demonstrate, any supposed derangement in the 
actions of the larger vessels must be excluded from the num- 
ber of causes which can materially affect the circulation. It 
cannot be denied, that a diminution of the elastic, or even of 
the muscular force of the small arteries, must be immediately 
followed by such a distension as will produce a resistance 
equal to the pressure : the distension will occasion an increase 
MDCCCIX. E 
