{192} DIAGNOSIS.--The affection bearing the closest resemblance to spontaneous purpura is scurvy; indeed, its supposed relationship to this disease has given purpura one of its synonyms, land scurvy. The two affections, however, are probably without the slightest relationship. They possess in common the hemorrhagic symptoms, both in the tissues and from free surfaces, but the resemblance does not extend much beyond this. Scurvy depends upon deprivation of fresh vegetable food and the use of unsuitable and insufficient food generally, and upon bad hygienic surroundings. Purpura may--frequently does--appear in broken-down constitutions, but it equally attacks the strong and vigorous, while the character of food exerts no special influence on its production. Scurvy only follows long-continued privations and as a culmination of a train of distressing symptoms. Purpura appears in the midst of health, or after brief premonition, or during convalescence from totally unrelated diseases. In scurvy there is a decided tendency toward ulceration, which is absent in purpura. In scurvy the mouth and gums inflame and ulcerate, the latter becoming swollen, spongy, and of a bluish-red color. In purpura, ulceration of the buccal mucous membrane does not occur, and the gums are pale and intact. The curative influence of fresh vegetables, lime-juice, etc. in the treatment of scurvy is not observed in purpura. It has been claimed that purpura is but a mild degree of scurvy: this cannot be so, for we may have a mild scurvy or a severe, even fatal, purpura. The hemorrhagic diathesis, or hæmophilia, presents points of analogy with purpura. Here, however, is found the almost constant history of heredity and the implication only of persons of the male sex. The disposition to bleed at all times upon the receipt of the smallest injury is quite unlike the suddenly-developed and transitory hemorrhages of purpura, which are also more generally distributed. With the secondary hemorrhagic effusions and ecchymoses that occur in conditions of profound alterations of the blood and blood-vessels in cases of malignant small-pox, scarlatina, typhus fever, etc., and in some cases of poisoning, as from phosphorus, spontaneous purpura presents identities, but the history of the complaint and the condition of the patient will prevent error. A knowledge of the circumstances will serve to distinguish purpura simplex from the petechiæ and small ecchymoses produced by fleas, by diminished atmospheric pressure, by coughing, in the course of Bright's disease, etc.