158 
ON ABSCESS. 
and their cysts, dense and much thickened, are not readily capable 
of extension, so that the pus remains inoffensively lodged in its 
cyst. 
I have no doubt that abscesses continue, occasionally, a long 
time unchanged, producing little inconvenience or disturbance to 
the constitution ; and these instances I have observed more parti- 
cular when deep-seated. I recollect a case of this kind, a little 
time past, in a horse destroyed in consequence of an accident, and in 
dissection of which an abscess presented itself of the size of a hen’s 
egg in front of the renal capsule, and which was the only morbid 
appearance that we observed. 
The cyst appears to increase in thickness and firmness, and the 
tissues by which it is environed change their condition. In this 
state, the purulent matter is, as it were, isolated from the surround- 
ing parts, and may so continue to produce no cognizable symp- 
toms, until excited by some fresh circumstance of excitation, when 
the disease will commence the usual course. This character of an 
abscess, however, is comparatively rare. In the general course, pus 
increases instead of diminishing in volume, distends and excites 
the adjoining structures, and, endeavouring to find an outlet, takes 
the direction of the skin, or one or other of the mucous surfaces. 
This is the grand law of the animal economy with regard to the 
formation and continuance and disappearance of pus. Thus, by the 
vital resistance which is ever opposed to such matters as are inju- 
rious and hurtful to the textures of the body, they are thrust, 
by a uniform procession of phenomena, to the nearest and least 
opposing part of the surface, there to be expelled from the system 
altogether. 
It is of importance to the practitioner to know the morbid phe- 
nomena as they progress in succession, in order to relieve the sys- 
tem of these collections of pus, and especially that formed in deep- 
seated or internal abscesses. From extension of the suppuration, or 
continued secretion from the lining membrane of the sac, the fluid 
is constantly augmenting. This increase of matter exercises a dis- 
tending force from the centre of the abscess to the walls, with an 
equal degree of pressure on the whole circumference, thus forcing 
outward the adjoining parts to which the parietes are applied. 
Such of the surrounding textures as exercise the least resistance 
yield to the increasing pressure ; and in this direction the abscess 
extends in the line that is free. It will be readily observed, that the 
parts situated beneath or more deeply than the parietes of the 
abscess must exercise the greatest force of resistance, while the 
textures placed exterior to it, and deprived of such aid, are more 
easily detruded by the accumulation of fluid. 
In further reference to the pointing of abscesses, it may be ob- 
