Etiology. 217 



monia, pliaiyngitis, influenza, in rare cases catarrli of the upper 

 air passages or of the intestines, and pyemia of the sinuses of 

 the head, caries of bone, exanthema of the skin, abscesses from 

 any cause, and gangrenous areas in the subcutaneous connective 

 tissue, or in the internal organs. As all of these diseases are 

 associated Avitli the presence of micro-organisms, and as the 

 purpura hemorrhagica sometimes occurs in the form of an en- 

 zootic, it may be accepted that micro-organisms are either 

 directly or indirectly incriminated in the development of the 

 disease. The indirect influence of the microbes, and the appear- 

 ance of the disease, is substantiated by the fact that the affec- 

 tion is not transmitted from infected to healthy animals, and 

 cannot be transmitted artificially either by inoculation of secre- 

 tions from the affected animals, or with blood (Haubner, Her- 

 ing), nor by direct transfusions of blood (Arloing). 



The characteristic hemorrhages and serous exudations in 

 the disease indicate a severe affection of the vessel walls which 

 in all probability may be explained by the fact that chemical 

 substances wdiich circulate in the blood reduce the normal elas- 

 ticity and resistance of the vessel walls. While this may be 

 the result of a change in the blood, through which the nutrition 

 of the walls of the vessel becomes diminished, and the watery 

 consistency of the blood in itself facilitates the transudation of 

 the blood plasma, a direct toxic action appears much more 

 probable in consideration of the quick, sometimes very abrupt 

 hemorrhages and serous infiltrations. Since, according to 

 observations, pathogenic bacteria produce toxic substances, 

 poison of similar origin may be suspected as the etiological fac- 

 tor of this disease. 



According to Dieckerhoff 's conception these toxins form in 

 necrotic or suppurative lesions which develop in any part of the 

 body through the action of the micro-organisms during the 

 course of the primary disease. This supposition is very prob- 

 able, as the diseases preceding petechial fever as a rule are 

 those in which the abscesses or gangrenous areas which develop 

 in the course of the disease communicate either originally or 

 later with the outside world, whereby micro-organisms may 

 readily gain entrance into the body. These organisms may then 

 multiply in the exudates or the necrotic tissues, and produce 

 chemical poisons which are later absorbed by the circulation. 

 In rare cases petechial fever apparently develops independently 

 of other diseases, or in connection with fresh injuries (castra- 

 tion), but even in such cases local necrotic processes cannot be 

 excluded with certainty. Accordingly purpura hemorrhagica 

 should be considered as an infectious disease in which, however, 

 the incriminated virus (probably the pyogenic streptococcus 

 which because of its ubiquity easily gains entrance into the 

 necrotic tissue), exerts its pathogenic action indirectly with 

 its specific toxic products. 



