It is commonly taught in Continental schools that the internal causes probably operate after the manner of a deleterious substance, which, being introduced into the circulation, occasions a putrefaction of the fluids. However, the doctrine is supported by no sort of proof, and may be considered as entirely hypothetical, if not decidedly erroneous. Certain poisonous, acrid, caustic substances taken inwardly, or introduced under the skin, may have the same effect by annihilating the vital action, or destroying the texture of the parts. But though these observations may all be entirely correct, they by no means justify the conclusion that the internal causes of mortification ever act by inducing a putrefaction of the fluids.

There is, however, an unquestionable specimen of mortification from an internal cause, and that is the introduction of rye into the stomach of herbivorous animals. It occurs in districts only after wet seasons in which the grain is affected with a particular disease; in this disease the grains of rye grow to a large size, acquire a black colour, and have a compact horny consistence. The species of mortification produced by eating this substance produces the following symptoms - the part affected becomes insensible and cold, and, in the progress of the disorder, dry, hard, and withered; stupidity and delirium finally ensue.

The external causes of mortification which are manifest, and act mechanically or chemically, are as follows: - Burns, excessive cold, the application of caustics, the presence of any ichorous, urinary, or faecal matter effused in the cellular substance, violent contusions, bad fractures, a high degree of inflammation, and everything that has the power of stopping the circulation and nervous energy in parts.

Inflammation must, therefore, be looked upon as one of the most frequent causes of mortification. But it will be as well to bear in mind that death of a part may take place without any well-marked appearance of previous inflammatory disorder, and the latter, even when present, has frequently less share in the mischief than other incidental circumstances, and is in reality only an effect of the very same cause which produces the sphacelus itself. It is often a matter of doubt whether actual inflammation precedes the occurrence or not, for a part before it mortifies is in certain instances only affected with pain, and with no degree of preternatural redness. Lastly, when mortification is unquestionably preceded by inflammation, there are so many varieties of the disorder, depending on incidental causes, that these latter demand more attention than the inflammation.

The following circumstances are, therefore, capable of influencing in a very great degree the disposition of inflammation to terminate in mortification: -

1. The powers of the part in which the inflammation occurs being naturally weak, as in fibrous membranes - for example, the scrotum, etc.

2. The remote supply of blood, or nervous energy, as in the lower extremities.

3. Obstruction to the return of blood.

4. To the supply of blood.

5. Disease in the heart, or vessels.

6. Debility from age, disorder of the digestive organs, or fever.

7. Poor living, foul air, improper food.

8. Impairment of organisation from external injury.

9. Impairment of the nervous power by poisons.

10. Undue excitement of weakened parts.

11. Depressing remedies.

12. Pressure and tension.

13. Excessive violence of inflammatory action, and

14. Peculiar disposition in the constitution.

Healthy phlegmonous inflammation seldom ends in mortification, except when it is unusually violent and extensive.

The symptoms of mortification from inflammation take place variously, yet generally as follows.

The pain and sympathetic fever suddenly diminish, the part affected generally becomes soft, and of a livid colour, losing at the same time more or less of its natural warmth and sensibility. In some places the cuticle is detached, while in other situations vesicles arise, filled with a clear or turbid fluid. Such is the state to which we apply the term gangrene, and which stage of the disorder too often rapidly advances to sphacelus, when the part becomes cold, black, fibrous, senseless substance, called in technical language a slough.

Again, it merits notice, that in cases in which gangrene immediately succeeds inflammation, these two morbid states may, in some measure, be regarded as stages or periods of the same disease. They pass insensibly into one another. Nor is it possible to say precisely where the one state ends and the other commences. The symptoms of inflammation in these cases do not disappear before those of gangrene come on, but seem rather to undergo a gradual and almost imperceptible change or conversion into one another. The redness acquires a deeper tinge and spreads farther than formerly, the swelling increases and becomes more doughy, and in this incipient stage, the gangrene, particularly when it attacks the cutaneous texture, often bears a considerable resemblance to erysipelas. It must also be observed that the part of the body which becomes affected with gangrene does not immediately lose its sensibility, for the pain, on the contrary, is often very much aggravated by the approach of this state. The blood also still continues to circulate, at least in the larger vessels of the part, but perhaps with less force, and, from the resistance which it meets with in passing through the capillaries, in less quantity than formerly. The serous effusion into the cellular membrane continuing to increase, and the action of the absorbents and sanguiferous vessels to diminish, the part becomes at length incapable of being restored to its former office in the animal economy. It is, therefore, in its earlier stages only that gangrene is to be considered a* an affection admitting of cure, for there are limits, beyond which if it pass, recovery becomes impossible. These limits it may not be easy to define in every instance, but they form the boundaries between incipient gangrene and the ultimate termination of that state in sphacelus.

Mortification often arises from a mechanical obstacle to the circulation of the blood; thus, the blood may be hindered from arriving at or returning from a part. In both cases mortification is the consequence of the cessation of the functions of nutrition, either from a deficiency of the arterial or a stagnation of the venous blood. A deficiency of the arterial blood may be occasioned by ligature, by coagulated blood, organised or unorganised fibrine, and in several other ways. Therefore there is no tissue nor organ of the body which may not become affected with mortification as the immediate or mediate effect of inflammation. Mortification is, however, much more frequently observed in those organs in which the vascular system predominates, or in which an inordinate accumulation of blood is readily produced on account of their greater sensibility, and their direct exposure to the influence of those causes which give rise to inflammation. Hence the reason why gangrene and sphacelus occur more frequently in the skin and cellular tissue, mucous membranes, and lungs than in any other tissue or organs of the body as immediate effects of inflammation, and why they are so rarely observed in serous and fibrous tissues, which contain few or no bloodvessels. In fact, these tissues are never found in a state of gangrene or sphacelus unless the cellular tissue, with which they are in contact, and from whose vascular system their nutrition is derived, has previously been diseased.

The red line appears in the form of a narrow circle, indicating the "boundary between the dead and living parts, and the commencement of the adhesive inflammation, which nature employs to stop the progress of the disorder. Ulceration then takes place along the internal border of the inflamed skin, and a separation is thereby affected between the living and dead tissues, the latter falling off in what is termed a slough. A groove is first formed by the ulcerative process on the surface, and advancing by degrees more and more deeply, at length accomplishes the perfect separation. The loss of substance which is thus occasioned, is repaired to a greater or less extent by means of coagulable lymph which is thrown out on the denuded surface, and which, becoming organised, assumes a membranous or granular form, according to the situation of the part, or the nature of the tissue to be repaired, and constituting ultimately what is denominated a cicatrix.

Treatment Of Mortification

In the treatment we must always have one thing under consideration, namely, whether the case is acute mortification, attended with inflammation and inflammatory fever, or whether it is a chronic mortification beginning without fever, or attended with a sinking fever and great prostration of strength. By arriving at a correct decision you establish a useful general principle for your guidance, especially in the commencement of the treatment

When mortification is acute, and seems to depend on the violence of inflammation, the first indication is to moderate the inordinate action of the sanguiferous system, by the prudent employment of such means as are proper for counteracting inflammation. In short, relief must be sought in the administration of purgatives, diaphoretics, and diluents, and in abstinence from all substances which have a tendency to excite, or to augment, the febrile action. Opium must be given to allay the pain, and aconite to reduce the frequency of the pulse. When there is great prostration, the strength must be supported by tonics and good food. Now, of all the medicines hitherto recommended for the stoppage of mortification, none ever acquired such a character for efficacy as Peruvian bark. It is said that this remedy often stops, in a very evident and expeditious manner, the course of the disorder. Being a powerful tonic, it is thought to operate by strengthening the system, and thus maintaining in every part the necessary tone for resisting the progress of mortification. But whatever be its mode of acting, it ought to be amployed in almost all cases of mortification as soon as the violence of the inflammatory symptoms has been subdued.