290 Fischer's Theory of Edema [Dec. 



and not mere blood pressure changes in the edema of the kidney, it does 

 not surprise us to recall the well-known fact that ligation of the portal 

 vein is followed by no grossly apparent morphological changes in the 

 liver — the portal vein carries only venous blood to the liver, and so 

 changes in the parenchyma due to the production of acids and a conse- 

 quent edema of the hepatic tissues is not to be expected. Quite a dif- 

 ferent picture is obtained when the hepatic artery is ligated. In spite of 

 the fall in blood pressure brought about by this means the liver rapidly 

 develops an intense edema. This result is quite expected on the basis 

 of our theory, and indicates very clearly that the real reason why a 

 passive congcstion leads to an edema of the liver is because it inter- 

 feres with the necessary flow of arterial blood through the organ via 

 the hepatic artery. (Page 144.) 



Fischer's views on the cause of edema of the lungs, are stated 

 in part as follows (pp. 149-156) : 



The problem of pulmonary edema is identical with the problem of 

 the edema of such an organ as the liver. The reason for this is at once 

 apparent when we call to mind the fact that the vascular arrangement 

 in the lungs is very similar to that which we previously discussed for 

 the liver. Just as the liver, so is the lung supplied with two blood 

 streams — with a venous stream through the pulmonary artery, which 

 only passes through the lung for purposes of oxygenation, and an 

 arterial stream through brauch es from the thoracic aorta, the bronchial 

 arteries, which supplies the parenchyma of the lung with oxygen. The 

 blood brought through these nutrient arteries leaves the lung in part 

 through the bronchial veins, in part admixed with the blood of the 

 lesser circulation through the pulmonary veins. The various facts at 

 hand on the experimental production of pulmonary edema are all easily 

 interpreted as soon as we say that an edema results whenever the 

 oxygen supply to the parenchyma of the lung is sufficiently interfered 

 with. (Page 150.) 



This conception of edema can be tested in yet another way. If 

 the lung becomes edematous through any condition which interferes 

 with a normal oxygen supply to the parenchyma, then it ought to be 

 particularly easy to produce an edema in a lung that has been removed 

 from the body. As a matter of fact, the most intense edemas of the 

 lung which simulate in every ivay those ohserved at the atitopsy table 

 may be produced in lungs removed from the body, and in the entire 

 absence of any such blood pressures as are considered active in the 

 current theories of pulmonary edema. (Page 153.) 



