Mortification is of two kinds; the one without any or much inflammation, the other preceded and accompanied by it To this last species of mortification, the terms inflammatory, humid, or acute gangrene are often applied; while the second, or that which is preceded by little or no inflammation, has been distinguished by the epithets dry, or chronic, and sometimes idiopathic, when no external cause for the origin of the disease can be assigned. The expression hot gangrene has also been applied to mortification attended with inflammation, and cold to that which seems scarcely to be connected with it. at least in its commencement According to Hunter, inflammation is an increased action of that power which a part naturally possesses; and in healthy inflammation, at least, it is probably attended with an increase of power. In cases, however, which are to terminate in mortification, there is no increase of power, but, on the contrary, a diminution of it. This, when joined to an increased action, becomes a cause of mortification, by destroying the balance which ought to subsist between the power and action of every part There are, besides, cases of mortification preceded by inflammation which do not arise wholly from that as a cause; of this kind are the carbuncle, and the slough formed in cow and sheep, pox pustute.

The first general division of mortification, therefore, is into two kinds, namely, the inflammatory,humid, hot, or acute, and the dry, cold, or chronic. But the disorder is also subdivided into many species, which are determined by the nature of the particular exciting cause, and these are referred to the three following heads: First, Mortification from the cessation of the circulation; second, From the violent operation of mechanical, chemical, and physical agents; third, From the deleterious influence of certain poisons. It is remarked also that acute or rapid mortification is not necessarily humid, as the slough from the application of caustic potassa proves. Again, the doctrine that any case of mortification is entirely without inflammation has sometimes been deemed questionable; but whether mortification be a consequence of inflammation or not, it may perhaps with reason be considered as standing in the same relation to inflammation as adhesion, suppuration, or ulceration; they may all be preceded by a high degree, or it may be scarcely sensible.

When any part of the body loses all motion, sensibility, and natural heat, and becomes of a brown, livid, or black colour, it is said to be affected with sphacelus, that is, complete mortification; and so long as any sensibility, motion, or warmth continue, the state of the disorder is termed gangrene. This word is here made use of to signify only a degree of sphacelus, or rather the process by which any local disorder falls into the state of complete mortification. Frequently the terms are used synonymously, but it is to be observed that gangrene does not invariably end in sphacelus, nor is the latter always preceded by the former.

Dr. Thomson says, "I shall employ the term gangrene to express that state of mortification in inflamed parts which precedes the death of the part, a stage in which there is a diminution but not a total destruction of the powers of life, in which the blood appears to circulate through the larger vessels, in which the nerves retain a portion of their sensibility, and in which the part affected may still be supposed to be capable of recovery. The word sphacelus I shall use to denote the complete death or mortification of a part, that state in which the powers of life have become extinct, in which the blood ceases to circulate, and in which the sensibility of the nerves is lost; whether the dead or mortified part has or has not become actually putrid, or shown any tendency to separate and fall away from the living and sound parts."

Putrefaction, or the spontaneous process by which animal bodies are decomposed, is an accidental, and not a necessary, effect of the state of mortification. It takes place at very different periods after the death of particular parts, and these periods, it may be remarked, are always regulated, not only by external circumstances such as the humidity and temperature of the atmosphere, but also by the peculiar structure and morbid conditions of the animal structure, or organ, in which the putrefaction occurs.

The term sphacelus has, I know, been employed to express that a part is not only dead and completely mortified, but also that the part has become putrid, and is in a state of separation from the surrounding and living parts. But as putrefaction is not a necessary or immediate consequence of mortification or partial death in animal bodies, this use of the term sphacelus is obviously improper.

It is an interesting observation, made by one of the greatest pathological anatomists, that "as the descriptive characters of mortification were originally drawn from the appearance which this disease presents when it attacks the external parts of the body, they have ever since been employed by the pathologist as the means of enabling him to detect it in internal organs after death. It may, however, be fairly questioned whether the application of the term mortification has not been too restricted, and whether parts deprived of their vitality, and separated from the living tissues, should not be designated by the same appellation as those which, similarly circumscribed, differ from them only in point of colour, and perhaps smell. Softening of the cerebral substance of the mucous, and frequently of the serous membranes, constitutes a state of positive death; but the softened substance in those instances presenting neither the peculiar colour nor odour of the external parts when mortified, it has been considered proper to distinguish softening from mortification by a term expressive of its principal character - that of softness."

Now the causes of mortification are either internal or external.