The phagedaenic ulcer calls for more energetic means of disinfection; the whole of the affected surface is touched with the actual cautery at a white heat, or is painted with pure carbolic acid.  Relays of charcoal poultices are then applied until the spread of the disease is arrested.

For the irritable ulcer the most satisfactory treatment is complete excision and subsequent skin-grafting.

CHAPTER VI

GANGRENE

Definition—­Types:  Dry, Moist—­Varieties—­Gangrene primarily due to
    interference with circulation:  Senile gangrene; Embolic
    gangrene; Gangrene following ligation of arteries; Gangrene
    from mechanical causes; Gangrene from heat, chemical agents, and
    cold; Diabetic gangrene; Gangrene associated with spasm of
    blood vessels; Raynaud’s disease; Angio-sclerotic gangrene;
    Gangrene from ergot.  Bacterial varieties of gangrene.
    Pathology—­clinical varieties—­Acute infective gangrene;
    Malignant oedema; Acute emphysematous or gas gangrene;
    Cancrum oris, etc.  Bed-sores:  Acute; chronic.

Gangrene or mortification is the process by which a portion of tissue dies en masse, as distinguished from the molecular or cellular death which constitutes ulceration.  The dead portion is known as a slough.

In this chapter we shall confine our attention to the process as it affects the limbs and superficial parts, leaving gangrene of the viscera to be described in regional surgery.

TYPES OF GANGRENE

Two distinct types of gangrene are met with, which, from their most obvious point of difference, are known respectively as dry and moist, and there are several clinical varieties of each type.

Speaking generally, it may be said that dry gangrene is essentially due to a simple interference with the blood supply of a part; while the main factor in the production of moist gangrene is bacterial infection.

The cardinal signs of gangrene are:  change in the colour of the part, coldness, loss of sensation and motor power, and, lastly, loss of pulsation in the arteries.

#Dry Gangrene# or #Mummification# is a comparatively slow form of local death due, as a rule, to a diminution in the arterial blood supply of the affected part, resulting from such causes as the gradual narrowing of the lumen of the arteries by disease of their coats, or the blocking of the main vessel by an embolus.