PURPURA. 



499 



mark between a roseola or urticaria pulicosa, and other forms of roseola 

 and urticaria, it cannot be used to distinguish between purpura puli- 

 cosa and other forms of purpura. Besides the discovery of fleas and 

 of fresh flea-bites, the mere consideration of the region upon which the 

 purpuric spots are situated will often enable us to estimate their origin 

 correctly. Fleas generally lodge in positions from which they can 

 crawl between the folds of the shirt. Hence, when we find petechise 

 upon the neck and shoulders, and about the waist in women, while 

 few or none are visible upon other regions, especially upon surfaces 

 which are usually exposed, we may conclude that the haemorrhagic 

 spots are the vestiges of old flea-bites. 



2. Haemorrhage into the skin may proceed from over-distention and 

 rupture of its blood-vessels. Thus, after severe coughing, or after vio- 

 lent vomiting, we often see the face speckled with purpuric spots ; and, 

 when the venous circulation of the lower extremities is obstructed, we 

 often find purpura upon them, accompanied by varicosities of the veins. 

 Even intense fluxionary hyperaemia seems sometimes to cause rupture 

 of blood-vessels in the skin. At all events, the English physicians 

 describe an affection called purpura simplex, which appears in healthy 

 and robust subjects, particularly in those who indulge freely in spirit- 

 uous liquors. 



3. The most frequent source of haemorrhage into the skin is a nu- 

 tritive derangement of the walls of the blood-vessels. Under this 

 head comes the purpura senilis, one of the symptoms of senile maras- 

 mus, as well as the purpura which appear in severe constitutional dis- 

 ease, such as typhus, small-pox, measles, and scurvy, and that which 

 is the chief symptom of the morbus maculosus of Werlhoff. The pe- 

 liosis rheumatica, a form of purpura accompanied by rheumatic pains, 

 and which is only met with upon the lower extremities, is probably of 

 this class likewise. 



SYMPTOMS AND COURSE. Red spots resulting from haemorrhage 

 may be distinguished from similar spots caused by mere vascular dis- 

 tention, by the fact that the latter disappear under pressure of the 

 finger, while the former remain unchanged. They vary considerably 

 in size, situation, and duration ; but these variations, as well as the 

 subjective symptoms which accompany them, depend principally upon 

 the character of the original disease, or its complications. Hence, we 

 must refer to the chapters upon typhus, small-pox, measles, scurvy, 

 and morbus maculosus Werlhofii for a further account of these haemor- 

 rhages, and shall now merely add a few words about peliosis rheumat- 

 ica. This affection, first observed and recognized as a distinct disease by 

 Schonlein, usually attacks young subjects with delicate skin, who have 

 already suffered from rheumatism. It is generally accompanied bj 



