54:0 ABSORPTION. 



The general rapidity of the current in the .lymphatic 

 vessels has never been accurately estimated. As a natural 

 consequence of the variations in the distention of these ves- 

 sels, the rapidity of the circulation must be subject to con- 

 stant modifications. Beclard, making his calculation from 

 the experiments of Colin, who noted the quantity of fluid dis- 

 charged in a given time from fistulous openings .into the 

 thoracic duct, estimates that the rapidity of the flow in this 

 vessel is about one inch per second. 1 This estimate, how- 

 ever, can be only approximative ; and it is evident that the 

 flow must be much less rapid in the vessels near the pe- 

 riphery than in the large trunks, as the liquid moves in a 

 space which becomes rapidly contracted as it approaches the 

 openings into the venous system. 



Causes of the Movements of the Lymph and Chyle. 



Various influences combine to produce the movements of 

 fluids in the lymphatic system, some being constant in their 

 operation, and others intermittent or occasional. These will 

 be considered, as nearly as possible, in the order of their rel- 

 ative importance. 



Influence of the Forces ofEndosmosis and Transudation 

 (vis a tergo). The forces of endosmosis and transudation are 

 undoubtedly the main causes of the lymphatic circulation, 

 more or less modified, however, by influences which may 

 accelerate or retard the current ; but this action is capable in 

 itself of producing the regular movement of the lymph and 

 chyle. It is a force which is in constant activity, as is seen 

 in cases of ligation of the thoracic duct, an operation which 

 must finally abolish all other forces which aid in producing 

 the lymphatic circulation. "When the receptaculum chyli is 

 ruptured, as a consequence of obstruction of the thoracic duct, 

 the vessel gives w r ay as the result of the constant endosmotic 



1 BECLARD, Iraite tilementaire de Physiologic Humaine, Paris, 1859, p. 180. 



