662 MR. youatt’s veterinary lectures. 
and harmlessly over each other, and friction is prevented by 
easiness of motion. In disease they adhere to each other, and 
friction is destroyed by the impossibility of motion. Inflammation 
of a serous membrane is quickly followed by adhesion ; there was 
design in this, for from the increased sensibility of the membrane, 
and in spite of the polished surface and the lubricating fluid, pain 
and aggravated disease would result from the attrition of the parts. 
This does not so often take place in the quadruped as in the 
human being; for the lungs here resting on the sternum, instead 
or the elastic diaphragm, the motion is not so extensive. We oc¬ 
casionally, however, see in all our patients the lungs bound to the 
intercostals, or the opposed reflections of the pleura, not only by 
interposed bands, but their whole surfaces are agglutinated to¬ 
gether by firm organized adhesions. 
The Exhaled Fluid. —Every serous membrane has innumerable 
exhalent vessels upon its surface, from which a considerable 
quantity of fluid is poured out. This fluid, I have said, is of a 
serous character; it resembles the serum of the blood. In life 
and during health it perhaps exists in the chest only as a kind 
of dew, just sufficient to lubricate the surfaces. When we open 
the chest soon after death, we recognize it in the steam that 
arises, and in the few drops of fluid, which, being condensed, are 
found at the lowest part of the chest. 
The Absorbents. —The quantity, however, which is exhaled 
from all the serous membranes, must be very great; it is perhaps 
equal to or superior to that which is yielded by the cutaneous 
vessels. If so little is found in ordinary cases, it is because the 
absorbents are as numerous and as active as the exhalents, and, 
during health, that which is poured out by the one is taken up 
by the other: but in circumstances of disease, either when the 
exhalents are stimulated to undue action, or the power of the 
absorbents is diminished, the fluid rapidly and greatly accumu¬ 
lates. Thus we have hydrothorax or dropsy of the chest, as 
one of the sequelae, of thoracic inflammation ; and the same dis¬ 
turbed balance of action will produce similar effusion in other 
cavities. 
Nature of occasional Adhesions.—The character of the fluid varies 
under different circumstances of disease. Although albuminous— 
disposed to coagulate at certain temperatures, and under certain 
influences—it is easily and completely absorbed during health. 
Even in disease it sometimes retains its perfect fluidity ; but at 
other times, whether from actual increase of temperature pro¬ 
duced by inflammation, or from a degree of vitality or tendency 
to organization communicated to it, it coagulates over the 
whole of the surface of the pleura, or on spots of it, forming ex- 
