3io 



MOVEMENT OF CHYLE AND LYMPH. 



lymphatics arise. The presence of the fibrin-factors in the lymph formed as they 

 are from the breaking-up of lymph-corpuscles seems to indicate this. In inflam- 

 mation of connective-tissue, in addition to the formation of numerous new lymph- 

 corpuscles, a considerable number seems to be dissolved ; hence the lymph, and 

 also the blood, in this case contains more fibrin. Lymph-corpuscles are also dis- 

 solved within the blood-stream, and help to form the fibrin -factors. 



201. MOVEMENT OF CHYLE AND LYMPH. The ultimate cause of the 

 movement of the chyle and lymph depends upon the difference of the pressure at 

 the origin of the lymphatics, and the pressure where the thoracic duct opens into 

 the venous system. 



(1) The forces which are active at the origin of the lymphatics are concerned 

 in moving the lymph, but these must vary according to the place of origin (a) 

 The lacteals receive the first impulse towards the movements of their contents 

 the chyle from the contraction of the muscular fibres of the villi (pp. 292, 297). 

 When these contract and shorten, the axial lacteal is compressed, and its contents 

 are forced in a centripetal direction towards the large lymphatic trunks. When the 

 villi relax, the numerous valves prevent the return of the chyle into the villi, (b) 

 Within those lymphatics which take the form of perivascular spaces, every time the 

 contained blood-vessel is dilated the surrounding lymph will be pressed onwards, (c) 

 In the case of the pleural lymphatics with open mouths, every inspiratory move- 

 ment acts like a suction-pump upon the lymph, and the same is the case with 

 the openings or stomata of the lymphatics on the abdominal side of the diaphragm, 

 (d) In the case of those vessels which begin by means of fine juice canals, the move- 

 ment of the lymph must largely depend upon the tension of the juices of 



the parenchyma, and 

 this again must depend 

 upon the tension or 

 pressure in the blood- 

 capillaries, so that the 

 blood-pressure acts like 

 g a vis a tergo in the 



Fig. 223. rootlets of the lym- 



Section of central tendon of diaphragm. The injected lymph-spaces, phatics. 



h and h, are black. At/ the walls of the space have collapsed. [In some organa peculiar 

 jumping arrangements are brought into action. The abdominal surface of the central tendon 

 of the diaphragm is provided with stomata, or open communications between the peritoneal 



cavity and the lym- 



phatics in the sub- 

 stance of the tendon. 

 Von Recklinghausen 

 found that milk put 

 upon the peritoneal 

 surface of the central 

 tendon showed little 

 eddies, caused by the 

 milk-globules passing 

 through the stomata 

 and entering the lym- 

 phatics. The central 

 *'*> 224, tendon consists of 



Injected lymph-spaces (black) from the fascia lata of the dog. two layers of fibrous 



tissue arranged in different directions (fig. 223, b, c). When the diaphragm" moves during 

 respiration, these layers are alternately pressed together and pulled apart. Thus the spaces 

 are alternately dilated and contracted, lymph being drawn into the lymphatics through the 

 stomata (fig. 223, h). The same kind of pumping mechanism exists over the costal pleura. 

 The fascia covering the muscles is another similar mechanism. The fascia consists of two layers 

 of fibrous tissue, with intervening lymphatics (fig. 224). When a muscle contracts, lymph is 

 forced out from between the layers of the fascia, while when it relaxes, the lymph from the 



