Purpura rheumatica (also called _peliosis rheumatica_) is usually preceded by symptoms of malaise, rheumatic pains and sometimes swelling about the joints; these phenomena abate and frequently disappear upon the outbreak of the eruption. The lesions are pea- to dime-sized, smooth, non-elevated, or slightly raised, and of a reddish or purplish color; the eruption may be more or less generalized, most abundant upon the limbs, or it may be limited to these parts. It may end in a few weeks, or may persist for several months, new spots appearing irregularly or in the form of crops. As somewhat allied to this is another form (_Schoenlein's disease_), quite alarming in its symptoms. It is rare. It is characterized by symptoms partaking of the nature of rheumatism, purpuric spots, blotches and ecchymoses, erythema multiforme, and often associated with considerable edema. The throat is also usually invaded, and indeed the first symptom is commonly in this region. Considerable constitutional disturbance, of a threatening character, is commonly observed. Recovery usually takes place. _Henoch's purpura_, observed chiefly in children, resembles the above, with the erythema multiforme character and the [oe]dematous swellings more pronounced, while the actual purpuric symptoms are less conspicuous. Gastric and intestinal symptoms and hemorrhages from the mucous membrane are commonly noted. It is fatal in about 20 per cent. of the cases. #Describe the symptoms of purpura haemorrhagica.# Purpura haemorrhagica (also called _land scurvy_) is characterized usually by premonitory, and frequently accompanying, symptoms of general distress, and by the appearance of coin to palm-sized, red or purplish hemorrhagic spots or patches, smooth, non-elevated or raised. Hemorrhage from the mouth, gums and other parts, slight or serious in character, may occur. New lesions continue to appear for several days or weeks; and in exceptional instances, repeated relapses take place, and the disease thus persists for months. It may end fatally. #State the etiology of purpura.# In most instances no cause can be assigned. The disease occurs at all ages from childhood to advanced life, and in individuals, apparently, in good and bad health alike. The hemorrhagic type is oftener seen in subjects debilitated or in a depraved state of health. A microorganism is also looked upon as a factor by some observers, especially in the grave type of disease. #State the diagnostic characters of purpura.# The appearance, irregularly or in crops, of bright-red or purplish spots, evidently of hemorrhagic nature, and not _disappearing upon pressure_, and as they are fading, going through the several changes of color usually observed in any ecchymosis. #How does scurvy (scorbutus) differ from purpura?#