MOVEMENTS OF THE LYMPH AND THE CHYLE 267 



system, it is probable that the vessels contract on their contents, when 

 they are unusually distended, and thus assist the circulation, the action 

 of the valves opposing a regurgitating flow. This action, however, can 

 not have any considerable and regular influence on the general current. 

 Contractions of voluntary muscles, especially compression of the 

 abdominal organs by contraction of the abdominal muscles, peristaltic 

 movements of the intestines and pulsations of large arteries situated 

 against the lymphatic trunks, particularly the thoracic aorta, are all 

 capable of increasing the rapidity of the circulation of the lymph and 

 chyle. The contractions of voluntary muscles assist the lymphatic 

 circulation in precisely the way in which they influence the flow of 

 blood in the venous system ; and there is nothing to be added to what 

 has been said on this subject in connection with the venous circulation. 

 While a vis a tergo must be regarded as by far the most important 

 agent in the production of the lymphatic circulation, movement of the 

 contents of the thoracic duct receives constant and important aid from 

 the respiratory acts. 



