138 PATHOLOGY 



detached, form emboli. Purulent softening may occur, 

 followed by infectious emboli and pyemia. 



Edema or dropsy is that condition in which there is 

 an excessive amount of fluid in the tissues. The most 

 important causes of edema are: Increased blood-press- 

 ure, the result usually of heart disease or the pressure of 

 tumors upon the veins, etc. The fluid constituents of 

 the blood are thus forced through the vessel walls into 

 the tissues. Another cause is found in increased per- 

 meability of the vessel walls in Bright's disease, which 

 causes extensive changes in the vessel walls. The tis- 

 sues the seat of edema present a pale, swollen appear- 

 ance, of doughy feeling, and upon pressure an indenta- 

 tion remains behind. 



Ascites. Edema of the abdominal cavity is known as 

 ascites. 



Hydrothorax is the term applied to edema of the thor- 

 acic cavity. 



Inflammatory edema refers to edema around an in- 

 flamed area. 



