390 
INFLAMMATION. 
Suppose, then, that an animal receives an injury from a con¬ 
tusion, a kick, or a wound in some muscular part; at first, pro¬ 
bably, it is of slight consequence, and the horse continues his 
work as usual, but by and by stiffness and lameness (if it be on 
an extremity) ensue; the disturbance increases, and he is inca¬ 
pable of continuing in the performance of his duty. In this stage 
of the affection we shall find four of the symptoms I have enu¬ 
merated, viz.—heat, redness, swelling, and pain. Before we 
proceed further, let us inquire into these symptoms, chiefly as af¬ 
fording us an elucidation and proof of that which I take to be 
primarily and essentially necessary for the existence of an inflam¬ 
matory state, viz. an increased action of the arterial capillaries. 
In the first place, then, we find heat —heat greater than in a 
state of health, presuming, as I have done, that the inflammation 
is an external one, i. e. that its seat is not in the contents of any 
of the cavities of the body. Do not let me be understood to 
mean that the temperature of a part under local inflammatory 
action ever rises above the natural temperature of the blood in 
other parts, because I do not believe such to be the case. Mr. 
Hunter was the first who denied the hitherto received opinion of 
an increased heat in deep-seated or internal inflammation; and 
this idea, like all others of that truly great man, was founded 
upon direct experiment. He made an incision into the gluteal 
muscles of an ass, two inches deep, and ascertained the tempera¬ 
ture of the wound to be 100® F.; into the cavity he introduced a 
tin canula, one inch and a half long, having first placed at the 
bottom a piece of wood, in order to prevent union of the sides : 
next morning the plug of wood was taken out, and the thermo¬ 
meter introduced, when the mercury again rose to 100°, as it also 
did when introduced into the vagina of the same animal. The 
temperature was ascertained daily for about a week, during which 
time the inflammation was kept up, and was found to vary from 
99° to 101°, but it never exceeded that of the internal parts of 
the body. Other experiments were made with precisely similar 
results. Thus we see that the heat of a part labouring under in¬ 
flammation never exceeds that of the blood, yet, when any exter¬ 
nal portion of the body is so affected, the heat of that portion is 
increased several degrees. How are we to account for this ? It 
admits of very ready explanation by referring to the definition 
with which I set out—an increased action of the arterial capilla¬ 
ries ; but I fancy the supporters of a contrary doctrine would be 
puzzled to bring any physiological principle so to bear as to ex¬ 
plain this most general symptom of inflammation : if their theo¬ 
ries were correct, we should decidedly have the very opposite re¬ 
sult, viz. a decreased heat; but I will endeavour to set this before 
