igii] William W einher ger 3^7 



did not lead to anasarca. In extending their studies, however, 

 Cohnheim and Lichtheim observed that the infusions of normal 

 sodium chlorid Solutions would cause an edema of the skin in any 

 part of the body, if the skin was subjected to any moderate Irrita- 

 tion, such as a previous exposure to the sun, the painting of this part 

 with iodine or its immersion in hot water for a short period. 



As most of these procedures are productive of a mild superficial 

 inflammation — a pathological State characterized by a change in 

 the permeability of the vessel wall — a transudation of a clear lymph 

 rieh in proteids results, which is the underlying cause of the so-called 

 inflammatory edema. Cohnheim therefore concluded that the mild 

 Irritation of the skin in the experiments mentioned caused a certain 

 alteration of the endothelia of the capillary walls, which made them 

 more permeable to the fluid of the hydremic plethora. However, by 

 repeated transfusions of salt Solution, a chronic hydremia is pro- 

 duced, which probably leads to an increase of the permeability of 

 the vessel wall, thus becoming instrumental in bringing out edema 

 of the leg after ligation of the femoral vein. 



In this connection mention may be made of the instructive ex- 

 periments performed by Magnus. Transfusion of blood into an 

 animal, immediately after its death, invariably leads to anasarca. In 

 living animals transfusion leads to edema of the skin, if these ani- 

 mals previously received injections of arsenic. The latter being 

 a specific poison for the blood vessels, its aggravating effect upon 

 anasarca is a strong support of Cohnheim's theory of the impor- 

 tance of the permeability of the capillary wall in the production of 

 edema, 



According to Cohnheim the many forms of edema may be re- 

 duced to two classes : ( i ) Edemas which are due to excessive per- 

 meability of the capillary wall, and (2) edemas due to venous con- 

 gestion. Cohnheim lays stress on the fact that even in venous 

 congestion, blood pressure is not the only cause of the resultant 

 edema, the diminished velocity of the blood stream and the in- 

 creased permeability of the endothelial wall being contributing fac- 

 tors. As to the nature of this altered permeability Cohnheim does 

 not think it due to a simple physical process. He expresses the 

 view that the endothelial cell is a living tissue with a metabolism 



