ON INFLAMMATION. 
383 
labour in this morbid degree must begin to pulsate more forcibly ; 
and, as a natural consequence, it receives and propels more blood 
than in a state of health. When this morbid exertion has been 
continued some time, the heart sympathizes with the inflamed 
part, the pulse is increased in frequency, and we have sympathetic 
inflammation. 
The symptoms of local inflammation are heat redness, swell¬ 
ing, and pain. I shall consider these symptoms ’separately, in the 
order in which I have enumerated them. 
Heat .—I must premise that the actual temperature of the part 
is not increased, or, if increased at all, only in a very slight de¬ 
gree. The sensation of heat to our feelings is greater, because 
under inflammation more blood passes through the capillaries, 
and is changed from arterial to venous, and is able to retain less 
caloric; and, therefore, a greater quantity of heat, but still at the 
same temperature, is given off than the skin can readily dispose 
of. The fact of this increased quantity of caloric being evolved 
from an inflamed part goes a great way to overturn the theory of 
congestion ; for if the blood were stagnant in the vessels, instead 
of increased heat, we should have a diminution of temperature, 
since change of the blood is the source of the animal heat. The 
increased heat of an inflamed part is, therefore, dependent upon 
the increased quantity of blood passing through the part; not 
merely resting m the part, but absolutely passing through it. 
Redness .—In our patients we are only seldom able to avail 
ourselves of this symptom, on account of the hair which exists in 
most parts ; but in the eye and some other parts it is very evi¬ 
dent. Redness is, if possible, more conclusive on the subject of 
congestion than heat. It is impossible for a part to be more red 
than natural if the blood be stagnant or detained in its course ; 
for, instead of being red, it would immediately change to black. 
The increased redness must be referred to the same cause as 
increased heat,—a greater flow of arterial blood through the 
part. 
Swelling .—I have said that in inflammation there is an increased 
quantity of blood flowing through the part; the vessels which 
before were too minute to admit of the red globules become en¬ 
larged, and these globules flow through them without interrup¬ 
tion ; independent of this, it is said fresh vessels are often formed, 
'and these vessels also contain a portion of the circulating fluid. 
These circumstances alone would account for some portion of the 
swelling; but, besides this, we have some interstitial deposit, or 
an effusion of coagulable lymph into the surrounding cellular 
structure. 
«. Pain .—Pain is accounted for by the pressure of the distended 
