and then black; the skin itself becomes shrivelled and its outer layer stony or like horn because of evaporation. The entire part may become as dry as a mummy, but usually there are spots where some fluid remains, and these spots are soft and moist, and the dead tissue where it joins the living is sure to be moist. The moist areas become foul and putrid, but the dry spots do not. At the point of contact of the dead and living tissue inflammation arises in the latter structure, a bright-red line forms, and exudation and ulceration take place. This line of ulceration in the sound tissues is called the "line of demarcation." It is Nature's effort at amputation, and in time may get rid of a large portion of a limb, and then heal as any other ulcer. In dry gangrene from arterial obstruction there are gastro-intestinal derangement and some fever. The gangrene does not extend up to the point of obstruction, but only to a region in which the anastomotic circulation is sufficiently active to permit of the formation of a line of demarcation. Below this point inflammatory stasis arises, but before this can go on to ulceration the parts die. In cases where the arterial obstruction is sudden and complete the limb may swell considerably. This is due to the sudden loss of vis a tergo in the arterial system, venous reflux occurring and fluids transuding. In such a case, though the tissues contain some fluid and putrefy, the process is pathologically dry gangrene. Dry gangrene attacks the leg more often than the arm. Thrombus in an artery rarely causes gangrene except in the aged, as the circulation has time to adjust itself; but gangrene may follow thrombus, and when it does it comes on more slowly than does gangrene from embolus.

Senile gangrene is a form of dry gangrene due to feeble action of the heart plus obliterating endarteritis or atheroma of peripheral vessels. The vessels do not properly carry blood, and may at any time be occluded by thrombosis. In a drunkard, or in a victim of syphilis or tubercle, the changes supposed to characterize old age may appear while a man is young in years. It was long ago said, with truth, "a man is as old as his arteries." Senile gangrene most often occurs in the toe or the foot.

Symptoms. A man whose vessels are in the state above indicated is generally in feeble health and has a fatty heart and an arcus senilis (a red or white line of fatty degeneration around the cornea). His feet feel cold and numb, and they "go to sleep" very easily. He is dyspeptic and short of breath, and his urine is frequently albuminous. The arte

ries are felt as rigid tubes, like pipe-stems. He is in much danger of edema of the lungs and of dry gangrene. A very slight injury of a toe will produce extensive inflammatory stasis, which completely cuts off the blood-supply and causes gangrene of the part. Gangrene is usually announced by a blue spot, followed by a vesicle which lets out bloody serum and has a dry floor. The tissues adjacent to the dead toe become victims to stasis and gangrene, and the process ascends until it reaches tissue whose circulation is sufficiently good to permit of ulceration instead of gangrene, when a line of demarcation forms. The dry parts do not putrefy. They are anesthetic, hard, leathery, and wrinkled, and resemble a varnished anatomical specimen or the extremity of a mummy (hence the term mummification). Before the line of demarcation forms there is some burning pain; after it forms pain is rarely present. If embolism or thrombus in a diseased vessel caused the gangrene, the pain is severe. In senile gangrene the periphery is always dry, the part nearer the body being generally somewhat moist. A line of demarcation may start, but prove abortive, the tissue mortifying above it. This proves that tissue near the line is in a state of low vitality. An entire leg may become gangrenous. When a limited area is gangrenous constitutional symptoms are trivial or are absent, but when a large area is involved we find the fever of septic absorption. Death may ensue from exhaustion caused by sleeplessness and pain, from septic absorption, or from embolism of internal organs. many cases of senile gangrene thrombosis arises in the superficial femoral artery or its branches (Heidenhain), an observation it is important to bear in mind when amputating.

Treatment of Dry Gangrene.—When injury of a healthy artery causes us to fear dry gangrene the patient should be placed in bed and the part elevated a little, kept wrapped up in cotton-wool and warmed with hot bottles or water-bags. The dying part is dressed antiseptically, and the surgeon sees to it that the patient gets plenty of sleep and nourishment. It is advisable to give tonics and stimulants. Wait for a line of demarcation and amputate well above it. When on amputating no arterial blood flows, perform catheterism of the artery with a filiform bougie or a fine rubber catheter. Insert the instrument into the artery, and work it up and down to break up the clot. Bleeding will occur; wash out the clot and then tie the vessel.' If a person is of the type in which there is danger of senile gangrene, he should 1 See Mancozet's report before second Pan-American Med. Congress.

be cautioned against injuring his feet, especially cutting his corns carelessly, which is highly dangerous; any wound, however slight, requires rest and antiseptic dressing. He must wear woollen stockings, put a hot-water bag to his feet on cold nights, and attend to his general health. A little whiskey after each meal is indicated, and occasional courses of nitroglycerin are desirable.

When gangrene occurs, if it is limited to one toe or a portion of several toes, if it is a first attack, if there is no fever or exhausting diarrhea, if there is no tendency to pulmonary congestion, if appetite is fair and sleep refreshing, we can await the formation of a line of demarcation. While awaiting the line of demarcation dress the part antiseptically and raise it about two inches from the bed, apply warmth, give the patient nourishing diet, stimulants, and tonics; see to it that he sleeps, and watch for fever, diarrhea, pulmonary congestion, and kidney-failure. When a line forms, dress with antiseptic fomentations and iodoform, and every day pick away dead bits with the scissors and forceps. In many cases healing will occur; but even when the parts heal the patient will always be in deadly peril of another attack. If the gangrene shows a tendency to spread, if it involves more than a portion of several toes, if it is not a first attack, if there is sleeplessness, fever, exhausting diarrhea, absent appetite, or a strong tendency to pulmonary congestion, do not delay, but at once amputate high up. If the gangrene shows no tendency to limit itself, or if the patient develops sepsis or exhaustion, at once amputate high up. The best point at which to amputate is above the knee, so that the deep femoral artery, which rarely becomes atheromatous, will nourish the flap. Never amputate below the tubercle of the tibia. Some operators disarticulate at the knee-joint. Heidenhain affirms that so long as the gangrene is limited to one or two toes we should merely treat it antiseptically, elevate the limb, and wait for the dead part to be cast off spontaneously; if, however, it extends to the dorsum or sole of the foot, amputate at once above the knee. He further states that gangrene of the flaps almost always occurs in amputation below the knee, and high amputation is indicated in advancing gangrene with or without fever. When amputation has been performed and no arterial bleeding occurs, clots exist in the femoral artery. If such a condition exist, insert into the artery a fine rubber sound and break up the clot. When blood runs the clot is washed out (Severeanu).

1 Deutsche medicinische Wochenschrift, 1891, p. 1087.

In moist or acute gangrene (Fig. 34) the dead part remains moist and putrefies. It results from interference with venous return or capillary flow, as well as from arterial ingress. It may arise in a limb after ligation or destruction of its main artery and vein, after long constriction, after crushes and lacerated wounds, and after thrombosis of the vein. Moist gangrene may follow acute inflammation, or may be

due to local constriction (strangulated hernia), crushing, chemical irritants, heat, and cold.

Moist gangrene of a limb is seen typically when both vein and artery are damaged or destroyed. The leg swells and is pulseless below the obstruction; the skin becomes cold, livid, and anesthetic, and is raised up into blebs which contain serosanguineous fluid. The extremity swells enormously, there is pain at the seat of obstruction, and sapremic symptoms quickly develop. The bullæ break and disclose the deeper structures, which are swollen and edematous. The fetor is horrible. Portions of the extremity become emphysematous and crepitate on pressure. A line of demarcation soon forms.

Moist gangrene from inflammation is due to pressure of the exudate cutting off the blood-supply, or to loss of bloodcirculation because of microbic involvement of vessels and

clotting of blood. It occurs in phlegmonous erysipelas. When an inflammation is about to terminate in gangrene all the signs of inflammation, local and constitutional, increase; when gangrene occurs they cease, bullæ and emphysema are noted, with great swelling and all the other symptoms of molar death. The sudden cessation of pain is very suggestive of gangrene. The constitutional symptoms are those of suppurative fever and sapremia, or possibly of septic infection.

Treatment of Moist Gangrene.-In extensive moist gangrene of a limb wait for a line of demarcation, and amputate clear of and above it. While waiting for the line to form dress the dead parts antiseptically, wrap in cotton, apply heat, and slightly elevate the limb. Give opium, tonics, nour

ishing food, and stimulants. In inflammatory gangrene relieve tension by incisions and then cut away the dead parts, brush the raw surface with pure carbolic acid, dust with iodoform, and dress with hot antiseptic fomentations. Stimulate freely and feed well.

Gangrene due to infective organisms comprises—(1) traumatic spreading gangrene; (2) hospital gangrene; (3) phagedena; (4) noma vulvæ; and (5) cancrum oris.

Fulminating gangrene, gangrenous emphysema, gangrène foudroyante, or traumatic spreading gangrene, results from a virulent infection of a severe wound by streptococci and organisms of putrefaction. The injury damages the main vessels of the limb, the pulse below the injury is imperceptible, and the surgeon is often at this time uncertain whether to amputate at once or wait. This form of gangrene is commonest after compound fractures, and begins within forty-eight hours after the accident. It does not begin at the periphery, as does ordinary moist gangrene, but at the wound-edges, which turn red, green, and finally black; the extremity soon undergoes a like change and becomes mortified. The entire limb swells because of edema, the skin peels off, emphysema sets in, and the extremity becomes anesthetic and pulpy. The gangrene spreads up and down from the wound, and red lines run from above the wound. These are due to lymphangitis, the adjacent lymph-glands swell, and in thirty-six hours the gangrene may involve an entire limb. No line of demarcation forms. The system is soon overwhelmed with ptomains, and the patient has septic intoxication, or he passes into profound collapse with subnormal temperature. Traumatic spreading gangrene must not be confused with erysipelas. In erysipelas the color is red, pressure instantly drives it out, and on the release of pressure it at once returns. In early gangrene the color is purple, pressure fails to drive it out at all or only does so very slowly, and if the surface is blanched by pressure, on the release of pressure the color crawls slowly back.

Treatment. In treating traumatic spreading gangrene a line of demarcation need not be waited for, as none can form. Amputation should at once be performed high up, the flaps are brushed with pure carbolic acid, and stimulants must be given in large amount.

Hospital gangrene or sloughing phagedena is a disease that has practically disappeared from civilized communities. It formerly occurred in crowded, ill-ventilated hospitals. Some consider it traumatic diphtheria. Koch thinks it is due to