128 Disturbances of Circulation. 



distended by the increased and persistent pressure of the lymph- 

 atic transudate. 



Increased transudation is observed also in connection with in- 

 flammation and changes of the vascular walls caused by toxic 

 chemical agents acting either locally or, when circulating in the 

 blood, widely {irritative or inflammatory dropsy). One should 

 recall in this relation the influence of the slowing of the blood 

 current and vascular dilatation, together with possible shrinkage 

 and separation of the endothelial cells, combining to render the 

 vessel walls more permeable ; moreover, a number of poisons, as 

 some of the products of metabolism, seem to directly stimulate 

 the endothelium to increased secretory activity, to possess what 

 might be called a "lymph-driving" ( lymphogogue) action. In 

 addition it may be pointed out that in inflamed tissues the lymph 

 flow is impaired by the fact that the inflammation occasions 

 coagulation of the lymph and impairs the elasticity of the tis- 

 sues. Such features explain the occurrence of cedema around 

 tissues which are the seat of purulent or hsemorrhagic inflamma- 

 tion (collateral cedema). 



Dropsy is often concurrent with wasting diseases and abnormal 

 states of the blood characterized by poverty of its cellular ele- 

 ments and increase in its jiroportion of water, the so-called 

 cachectic or hydremic wdenia, as seen in cases of pulmonary 

 verminosis, fluke disease of the liver and chronic parenchymatous 

 nephritis. It is an open question in such cases whether the es- 

 sential fault in determining the dropsy is the dilution of the 

 blood which may perhaps make it filter more readily through the 

 vessel walls, or whether we should ascribe it to the presence of 

 metabolic products and other toxic matter in the circulating 

 blood impairing the vascular endothelium and permitting the 

 transudation because of an increased permeability. (Cohnheim 

 and Lichtheim failed to obtain dropsy by introducing large quan- 

 tities of sodium chloride solution into the blood of experiment 

 animals, even when as much as half of the blood was replaced 

 by the saline solution ; Gartner, however, succeeded in causing 

 an oedema in dogs by long continued infusion of salt solution.) 



No satisfactory explanation exists for the rather common 

 congenital anasarca of aborted calves. According to the investi- 

 gations of L. Franks the thoracic duct is sometimes missing in 

 these "watei: calves" (or "Dunstkalbern") : while in other cases 



