ON INFLAMMATION. 
323 
lion of a change in the texture of the blood itself—it became 
thicker and viscid. Cullen imagined that there was spasm of 
the capillaries or their orifices. Allen adopted the Italian theory 
of increased determination of blood to the capillaries, and dimi¬ 
nished action of these vessels on their contents, producing stag¬ 
nation of the fluid which they contain. Dr. Philip supposes that 
the vessels are dilated, and, therefore, the velocity of their con¬ 
tents diminished. Dr. Thompson imagines that there may be 
alternations of increased and diminished velocity ; and Dr. Hast¬ 
ings maintains that there is increased action of the larger arte¬ 
ries, while the capillaries are in their natural state. The oldest 
opinion, however, is the simplest and the best,—that inflamma¬ 
tion is an increased action of the capillaries. Not only a deter¬ 
mination of more blood to them, but the actual passage of more 
blood through them, and an increased discharge of all their 
functions. 
From a blow, or wound, or change of temperature, or various 
other causes, the nervous fibrils supplying the capillaries of a 
greater or smaller portion of the frame, and on, sometimes, a 
minute and circumscribed spot, are irritated. They act more 
powerfully on the muscular coat of the vessel; and the conse¬ 
quence of this is, that the capillary contracts more powerfully 
on its contents, and it more perfectly empties itself, and drives 
the blood forward with increased velocity. The elastic coat, 
which forms the external covering of the capillary as well as 
the artery, being closely connected with the muscular, is con¬ 
tracted with it, contracted likewise beyond its usual limit. The 
contraction being performed, the muscle ceases to act, and then 
the clastic coat, obeying the law of elasticity, returns again to 
its former calibre, and with an increased force and velocity 
equal to the contraction of the muscle. It does more than this: 
the vibrating string proceeds beyond the point from which it at 
first started, and the elastic coat of the capillary expands be¬ 
yond its natural calibre. There is thus rapidly formed, or 
would be formed, a vacuum, and of greater extent than usual ; 
and, by a mechanical law,—by the pressure of the atmosphere,— 
by the principle of derivation , more blood is solicited, flows on, 
and flows on more rapidly, and fills the vessels, and the tubes 
which were previously enabled to carry red blood carry more, 
and those whose calibre would not before give passage to the 
red particles are dilated and carry red blood too ; and so, as 
has been stated, not only more blood flows to the inflamed part, 
but through it. The proof of this is incontestible. If one limb 
only be inflamed, and a vein be opened in both the diseased 
limb and the sound one, and between the seat of inflammation 
