SOCIETY MEETINGS. 
370 
it is rapidly consummated. Like normal textures, new formations of every kind, 
tumors, exudates, pus, are liable to become necrosed. Fluids degenerate through 
necrosis into gangrenous ichor, the most infectious and destructive of its tribe. 
A general characteristic of gangrene is not easily given, so manifold are its 
forms, and so various are its causes. Soft parenchymata commonly breaks 
down into a diffluent pulp, marked by a bight degree of discoloration and of 
foetor. As decomposition proceeds, gases are generated in the part, principally 
sulphuretted hydrogen, ammonia, nitrogen and carbonic acid. These give rise 
to the emphysematous crackling which is so often associated with the gangrenous 
processes. The tissues at the same time undergo a process of softening or 
liquefaction, the limb becomes exceedingly offensive, and, owing to alterations in 
the transuded haemoglobin, changes from a reddish color to a brownish or greenish 
black. The characters of the dead part vary with its structure, its vascularity, 
the cause of the gangrene, the acuteness of the process, and the possibility of the 
access of atmospheric air. The more vascular the part, the softer the structure, 
and the more it is exposed to the atmosphere, the more rapidly and completely 
does it undergo decomposition. 
Bones, cartilages, and tendons, which are firm, hard tissues, containing com. 
paratively but few vessels, undergo very little alteration in structure and form; 
whereas softer parts are much more rapidly and completely destroyed. 
The occurrence of decomposition manifests itself in the first place in the blood 
contained in the part. The hemoglobin escapes from the red blood corpuscles, 
partly by exudation, and partly by the destruction of the corpuscles themselves, 
and dissolved in the liquor sanguinea, permeates the surrounding tissues. The 
corpuscles are ultimately completely annihilated, nothing remaining but a few 
minute granules. The staining of the tissues with the haemoglobin is known as 
post mortem staining, .and the appearances it presents are very characteristic. 
All the tissues may be more or less affected, but the living membranes of the 
heart and large blood vessels, being in immediate contact with the blood after 
death, are naturally more so than other parts. 
The staining is of a uniform pinkish red color, thus differing from the puncti- 
form and stratiform redness of hyperaemia, from which it must be carefully dis¬ 
tinguished. 
The amount of staining is in proportion to the rapidity with which the de¬ 
composition has taken place, and to the amount of blood contained in the part at 
the time of death. Gangrene has the import sometimes of a local, sometimes a 
symptom, of general disease. The conditions necessary to the former case are 
nearly reducible to arrested afflux of blood ; that is, stasis. It may begin by at¬ 
tacking fluid parts, and especially the blood, and extend from these to solid struc¬ 
tures, or it may affect them all at once. 
DEVELOPMENT OF GANGRENE. 
Gangrene is developed— 
First .—Out of absolute blood stasis, which may occur under various circum¬ 
stances. 
. (a) Every hyperaemia in organs, or sections of organs, particularly in para¬ 
lyzed or enfeebled, or obnoxious to debilitating influences, may degenerate into 
absolute stasis. This applies particularly to asthenic, hypostatic, hyperaemia in 
