and quite insensitive when touched. The skin around is generally congested or eczematous. The base is covered with a thin, sanious discharge, while there are either no granulations, or such as are present are small, flabby, pale and ill-formed. These ulcers often exist for years, and are usually attended with little pain, and though they are at times small, at other times extend nearly round the whole leg. They are often adherent to the periosteum, fascia or bone. Treatment.-The callous edges should first be softened by emollient dressings, and uniform pressure subsequently applied by a Martin's bandage, or by strapping and a bandage after Baynton's method. When very large, amputation under some circumstances may be called for.

The Varicose and Eczematous Ulcer.-These terms are applied to any ulcer, whatever its other characters, when associated respectively with a varicose state of the veins, or an eczematous condition of the skin. Both conditions frequently occur together, and are generally dependent on a varicose state of the veins, and will be described under Diseases of the Veins.

The Irritable or Painful Ulcer.-Though any ulcer may be irritable or painful, the above terms are generally restricted to a small, painful fissure about the anus (see Diseases of Rectum), and to a small, superficial, generally congested ulcer, commonly situated about the ankle, and occurring chiefly in women beyond middle life. The pain is often intense, and is generally believed to depend upon the involvement of the nerve endings. Treatment. The improvement of the general health, small doses of opium, and cauterization with nitrate of silver will often suffice to cure the ulcer. In inveterate cases an attempt may be made to divide the nerves subcutaneously after the manner of Hilton.

B. Ulcers whose Characters Depend upon their Specific Origin.

Strumous ulcers are generally due to the breaking down of enlarged tuberculous lymphatic glands, the bursting of subcutaneous strumous abscesses, or the ulceration of the so-called strumous nodules. They are generally multiple and often confluent, forming an irregular indolent sore. The edges are pale, bluish-pink, thin and undermined. The granulations are pale, oedematous, protruding, and readily bleed when touched. The discharge is thin, yellowish-green and scanty. Enlarged glands and cicatrices of ulcers are frequently present in their near neighborhood. The cicatrices are generally raised, pale pink or white, while the skin is often puckered in around them. Treatment. -Constitutionally that for struma. Locally the sore should be destroyed by paring away the edges, and scraping the base with

a Volkmann's spoon. The cicatrices may sometimes be dispersed by repeated blisterings.

Syphilitic Ulcers.-Primary ulcers or chancres are described under syphilis. Those occurring in the course of constitutional syphilis may be divided into the superficial and deep.

a. The superficial occur in the course of tubercular and pustular syphilides, and are often associated with patches of these eruptions on other parts of the body. They are usually circular or crescentic in shape, spreading by their convex margin, and healing on their concave. Their edges are sharp-cut and often surrounded by an areola of dusky redness; their base is but slightly depressed, and of a dark-red color, and is often covered by a yellow slough, or a rupial or ecthymatous scab. Several of these ulcers frequently coalesce, giving rise to a serpiginous or annular form of ulceration, which is very characteristic of syphilis. Treatment.-See SYPHILIS.

b. The deep are due to the breaking down of gummata. They are circular or oval in shape; their edges are steep, sharp-cut, slightly scooped out, and of a dull-red color; and their base is depressed and covered with a yellow slough and the débris of breaking-down tissue. They leave slightly depressed, white cicatrices, often surrounded with pigmentation. Treatment.Constitutionally, iodide of potassium should be given in full doses, and in obstinate cases mercury; while locally a poultice may be applied till the slough has separated, and then black wash, iodoform, or the red oxide of mercury ointment.

Gouty ulcers are such as are met with over gouty parts. They are small and superficial, and the discharge as it dries leaves a chalk-like deposit of urate of soda on the surface of the ulcer.

The Scorbutic Ulcer.-Should an ulcer exist in a person affected with scurvy, its surface becomes covered by a spongy, dark-colored, strongly-adherent, fetid crust, the removal of which is attended with free bleeding, and is followed by the rapid reproduction of the same material.

Lupous, epitheliomatous, rodent, carcinomatous and sarcomatous ulcers will be found described in the sections on Lupus, Tumors, etc.

GANGRENE OR MORTIFICATION.

Although gangrene may occur from causes other than inflammation, it is, as we have seen, one of its results, and is therefore described here. It differs from ulceration in that the affected tissue dies en masse instead of in a molecular

manner.

General Outline of the Process.-Let us take as our type gan

grene as it occurs in a superficial part as the result of inflammation. The part which was previously hot, red, painful and swelled becomes cold, gradually falling to the temperature of the surrounding medium. The pain, which just before the gangrene sets in, is often of a peculiar burning character, ceases, and sensation is completely lost both to the touch and all other external stimuli. The skin, formerly red, becomes of a peculiar pale earthy color, mottled in places with patches of green or red. Now the cuticle separates in the form of blebs, or can be removed by gentle touching, leaving the dermis below wet and slippery. A peculiar crepitant sensation is felt on pressure, on account of the formation of putrescent gases in the tissues, which, if cut into, are found stained and infiltrated with a red fluid. The part now becomes blackish-brown, and exhales the peculiar odor of decomposing animal matter. Supposing the process ceases to spread, ulceration is set up at the expense of the living tissue bordering upon the gangrenous part; a bright-red line (the line of demarcation as it is called) is thus formed between the living and the dead; this deepens, and finally the gangrenous part is thrown off in the form of a sphacelus or slough, leaving a healthy granulating wound which cicatrizes in the usual way. The minute changes which occur during the above process are as follows: The infiltration of the leucocytes is so excessive that the blood supply of the tissue at the focus of inflammation is cut off and the part loses its vitality and dies; the red corpuscles break down, and their hæmoglobin is dissolved in the albuminous fluid infiltrating the parts, and stains the tissues a deep red. Septic bacteria make their way through the skin and putrefaction sets in. The tissues disintegrate and liquefy, sulphuretted hydrogen and other putrescent gases are generated, and the part rapidly passes through changes similar to those it would undergo if it were no longer in connection with the body.* When the gangrene ceases to spread, the living tissues immediately in contact with the dead part, owing to the irritation of its presence, become intensely congested (hence the red line of demarcation) and, subsequently, in consequence of their infiltration with leucocytes, soften and break down into pus; and their cohesion being thus lost, the dead part is thus cast off. Hemorrhage, during the process of separation, is prevented by the thrombi filling the vessels, which, subsequently, become permanently sealed as explained in the section on hemorrhage. Granulations in the meanwhile spring up on the surface of the

* Unless bacteria enter, the tissues undergo fatty changes (necrobiosis), not putrefaction.

ulcer left on the removal of the slough, and cicatrization is effected in the way described under ulceration. In the meanwhile, if the gangrene is at all extensive, or affects a vital organ, as a knuckle of intestine, it exercises a marked effect on the constitution. The vital powers are depressed; the heart's action is feeble, the pulse small, soft and quickened, the tongue dry and brown, the lips are covered with sordes, and the appetite is lost; while later, as the products of putrefaction are absorbed into the system, symptoms of septic poisoning (sapræmia) set in.

The above may be taken as a type of what is called inflammatory gangrene. Gangrene, however, may result from causes other than inflammation, and the dead part, instead of becoming swollen and infiltrated with fluids, may shrivel up and become quite dry and mummified. Hence the division sometimes made

into moist and dry gangrene.

The moist or dry appearance of the part depends upon whether the tissues at the time that gangrene supervenes are charged with blood, as in inflammatory gangrene and in gangrene from venous obstruction; or, whether they are more or less deprived of blood, as in gangrene from the blocking of the main artery supplying the part. The two conditions sometimes run into one another, the dead part at first being moist, and subsequently becoming, as the fluids evaporate, more or less dry. The different appearances presented by the gangrenous part will be further described under Varieties of Gangrene, as it varies according to the cause producing it. The causes of gangrene, therefore, must first be considered.

Causes. The immediate cause of gangrene, whether the process is induced by inflammation, as described above, or otherwise, may be said to be any agent which is capable of destroying the vitality of the tissues or cutting off their nutrient supply. The agents capable of inducing one or other or both. of these conditions are very numerous. Some of them are in themselves alone sufficient to act in this way. For others, however, to become operative, certain prior changes in the tissues would appear to be necessary. The causes of gangrene, therefore, may be considered under the heads of predisposing and exciting.

The Predisposing Causes are such as impair the vitality of the tissues, and render them less able to resist injurious influences. They, therefore, include those already given under Inflammation (page 13), and among them may be especially mentioned old age, feeble action of the heart, chronic congestion of a part, deteriorated blood as in diabetes and Bright's disease, and impairment

or loss of nerve influence from injury or disease of the nervecentres or nerve-trunks.

Exciting Causes.-These may be considered under the following heads: 1. Physical or chemical agencies, which act by directly destroying the vitality of the tissues. Among these may be mentioned mechanical violence, as a severe crushing of part of a limb; excessive heat, as in burns and scalds; intense cold, as in frost-bite; chemical action from strong acids, alkalies, putrid secretions, and the like. Although these may act by directly killing the tissues of the part, their action is often aided by inflammation, as seen, for instance, in a crushed foot, where both the injury and the subsequent inflammation determine the death of the member. 2. Inflammation causes gangrene in part by the pressure of the inflammatory exudation and the stasis in the vessels cutting off the nutritive supply, and in part by the action of the irritant causing the inflammation. The latter is especially the case in the septic and infective inflammations, the noxa here being either the products of putrefaction (ptomaines) or micro-organisms (bacilli or micrococci). Some inflammations always terminate in gangrene, as carbuncle and malignant pustule. The manner in which micro-organisms act in producing gangrene is not determined. 3. Obstruction to the arterial supply, as from ligature of the main artery, embolism, thrombosis or rupture of the artery supplying the part, and spasms of the arterioles due to long ingestion of ergot. 4. Obstruction to the capillary circulation from thrombosis or pressure. As examples of this may be mentioned, bed-sores from pressure of the part between the bed and a point of bone; the death of the skin and bone in cellulitis and periostitis respectively from compression of the capillaries by the inflammatory effusion; local sloughing from the pressure of a splint or a new growth; cancrum oris from thrombosis of the capillaries, etc. 5. Obstruction to the venous return as seen in strangulated hernia, paraphimosis, tight bandaging, etc. Obstructed venous return, however, is generally associated with obstruction to the arterial supply as well. The Signs of Gangrene vary considerably according to the The general symptoms in the acute inflammatory form have already been given in the outline of the process (page 37). Those of the special forms will be further mentioned under varieties of gangrene and elsewhere, as in the section on Cancrum Oris, etc.

cause.

The Treatment, like the symptoms of gangrene, depends so much upon the cause and nature of the gangrene, that its details can only be given under the special varieties. Here, however, it may be said that the general indications for treatment, what