Before operating on subjects past middle life, it should be a routine practice to note the color and temperature of the foot, both in the dependent and horizontal positions. The _anterior tibial pulse_ should also be felt for and its absence or intensity noted. A question to the patient as to diabetes or thickened arteries may also elicit valuable information. A very weak or absent anterior tibial pulse (the knack of feeling the pulse here must be acquired), or peculiar nodules about the nail grooves, are evidences of an encumbered arterial supply. Extreme redness or blueness in a foot in the hanging position, and pallor when elevated, also indicate a similar condition, or one in which the valves in the veins are impaired. It is in such conditions that the greatest care should be taken to avoid deep incisions except in the presence of positive indications. +Treatment.+ In general, amputation through healthy tissue is the rule in gangrene affecting any extremity through its entire thickness. The complete devitalization of even a digital phalanx requires that amputation be made beyond the next joint above. In traumatic gangrene it is the rule to amputate immediately through healthy tissue when restitution of the injured parts is known to be impossible. In senile gangrene the appearance of the line of demarcation indicates the extent of the devitalized area and establishes the point of amputation beyond the next joint above. Diabetic gangrene presents the peculiarity of a slow and steady advance, unless an unusually high amputation be performed. Thus, if the great toe is the site of the beginning of a true diabetic gangrene, amputation through the lower third of the thigh is indicated; otherwise the prognosis is very bad. Inflammatory gangrene, or as it is more properly called _gangrenous cellulitis_, is a rapidly spreading infective process which destroys tissue as it advances. It is an acute suppurative process causing large sloughs. It is a form of cellulitis requiring drainage and disinfection. Frost bite may involve tissues to any depth and to any surface extent. Lesions of circumscribed contour result in the sloughing away of the area involved and never require amputation. (See “Frost bite.”) In the event of a phalanx, toe, finger, foot, or hand being involved, the same rules as above laid down must apply. In this variety, however, it is important to allow sufficient time to elapse in order that the depth of the gangrenous process may be ascertained. Should the line of demarcation be apparent, after a few days the complete death of the tissues below is certain, and amputation becomes necessary. If, however, after a few days some slight bleeding or the appearance of a red point be apparent, the bone, and in all probability some tissue around it, is still viable. Haste in these cases should therefore be avoided. CHAPTER XII +DISEASES OF VEINS+