PURPURA SIMPLEX.--This is the mildest form of purpura, and may in many cases readily escape observation. It may begin abruptly, in the midst of health, without the slightest subjective symptom, or the extravasations may be preceded for several days by some discomfort, aching of limbs, sluggishness, anorexia, even a small amount of fever. The eruption usually appears first upon the lower extremities, preferably the flexor surfaces of the thighs (Duhring), but frequently upon the legs. It extends from these points to the upper extremities and trunk, usually sparing the face. The lesions vary in size from that of a pin-head to that of a fingernail (petechiæ), or they may be linear (vibices). They remain discrete, and do not increase in size throughout their course. Each spot of hemorrhage will endure for from one to two weeks. At first the lesions are of a livid red color, and declare their extra-vascular nature by remaining unaltered when subjected to pressure. The color of these spots changes, as in ordinary ecchymosis, in consequence of the metamorphoses of the hæmatin preparatory to its final absorption, from crimson to purple, to blue, to green, to yellow, and finally fades away. When recent, the spots appear sharply outlined, with sometimes a faint encircling zone of hyperæmia, but as they become older their margins grow indistinct. While the early lesions slowly disappear, others continue to develop, and the affection may thus be protracted for weeks. At times the petechiæ appear in crops, recurring every few days, the patient at one time apparently nearly well, at another time worse than ever. Finally, the symptoms definitely disappear, to return no more, or they pass into those of other forms of purpura. During the course of purpura simplex the blood-vessels of the skin alone are affected, the deeper tissues and mucous membranes probably remaining unchanged. Throughout the attack the general health may--usually does--remain good. As an occasional symptom there will be observed a few vesicles or blebs, containing blood, upon the skin. The extent of the general eruption may vary from a few scattered petechiæ to a copious and startling {188} number of purpuric spots. The maintenance of the upright position tends to perpetuate the evolution of the lesions. In elderly persons purpura simplex is sometimes observed, and has been described by many writers as purpura senilis. Hillier, following Bateman, describes it as occurring in old women "upon the outside of the forearms in successive dark, purple blotches of an irregular form and various magnitude."[1] Aged men as well as women are liable to the affection, which may quite as well appear upon the lower extremities of either sex. It is altogether likely, however, that in such cases degenerations of the vascular walls alone may cause the extravasations. [Footnote 1: Reynolds's _System of Medicine_, vol. i. p. 792.]