ust
suffer a morbid degree of dilatation. These appear to be the only
circumstances under which a vessel can suffer such dilatation.

But if, while the powers of the vessels remain the same, the vis a
tergo, or propelling force, be diminished, or the propelling force
remaining the same, the power of the vessels become increased; then
an opposite condition or state of the vessels, viz. a preternatural
diminution of their area, will take place.

In the one case the distending force bears too great a proportion to
the resisting force; and preternatural distention is the consequence.
In the other the resisting force bears too great a proportion to the
distending force, and preternatural contraction is the consequence.

It is not necessary that the vessels should be in a state of greater
debility than in health, in order that an inflammation or distention
may take place: it is only necessary that the proportion which their
action bears to the propelling force be less than in health. If the
propelling force remain the same, the vessels must be in a state of
debility before an inflammation can take place; but if the propelling
force be increased by a fullness of the vessels and sthenic
diathesis, inflammation may take place, although the vessels of the
part act as powerfully as in health, or more so. But after
inflammation has taken place, as the vessels are preternaturally
distended, they must also be debilitated.

The degree of inflammation is not however proportioned to the
debility of the minute vessels of an inflamed part, but to the
diminished proportion of their power to the propelling force.

When, therefore, inflammation arises from an increased action of the
arterial system, or an increased propelling force, while the force of
the capillaries or minute vessels remains the same, it constitutes
what is called an active inflammation, and is to be cured by general
bleedings, and then by gentle applications of tonics to the part, to
increase its action; but when it arises from a debility of the minute
vessels, without any increase of the propelling force, it forms what
is known by the name of passive inflammation; in which general
bleeding is not required, but the application of stimulants and
tonics to the inflamed part to enable the vessels to recover their
lost tone, and restore the balance between their action and the vis a
tergo. From what has been said, it must be evident, that if
inflammation depend on the di