302 



ORIGIN OF THE LYMPHATICS. 



ducts of the tissues, proofs of their retrogressive metabolism, become mixed with; 

 the lymph-stream, so that the lymphatics are at the same time absorbing vessels. 

 Substances introduced into the parenchyma of the tissues in other ways, e.g., by 

 subcutaneous injection, are partly absorbed by the lymphatics. A study of these 

 conditions shows that the lymphatic system represents an appendix to the blood- 

 vascular system, and further that there can be no lymph system when the blood- 

 stream is completely arrested ; it acts only as a part of the whole, and with the whole. 

 Lacteals. When we speak of the lymphatics proper as against the chyle-vessels 

 or lacteals, we do so from anatomical reasons, because the important and consider- 

 able lymphatic channels coming from the whole of the intestinal tract are, in a 

 certain sense, a fairly independent province of the lymphatic vascular area, and are 

 endowed with a high absorptive activity, which, from ancient times, has attracted 

 the notice of observers. The contents of the chyle-vessels or lacteals are mixed 

 with a large amount of fatty granules, giving the chyle a white colour, which dis- 

 tinguishes them at once from the true lymphatics with their clear watery contents. 

 From a physiological point of view, however, the lacteals must be classified with 

 the lymphatics, for, as regards their structure and function, they are true lymphatics, 

 and their contents consist of true lymph mixed with a large amount of absorbed 

 substances, chiefly fatty granules. [The contents of the lacteals are white only 

 during digestion, at other times they are clear like lymph.] - 



196. ORIGIN OF THE LYMPHATICS. (1) Origin in Spaces. Within the connective- 

 tissues (connective-tissue proper, bone) are numerous stellate, irregular, or branched spaces, 



which communicate with each other by 

 numerous tubular processes (fig. 216, s) ; 

 in these communicating spaces lie the 

 cellular elements of these tissues. These 

 spaces, however, are not completely filled, 

 by the cells, but an interval exists between 

 the body of the cell and the wall of the 

 space, which is greater or less according 

 to the condition of movement of the proto- 

 plasmic cell. These spaces are the so- 

 called "juice canals" or'Saft-canalchen," 

 and they represent the origin of the lym- 

 phatic vessels (v. Recklinghausen). As 

 they communicate with neighbouring 

 spaces, the movement of the lymph is 

 provided for. The cells which lie in the 

 spaces exhibit amoeboid movements. 

 Some of these cells remain permanently 

 each in its own space, within which, 

 however, it may change its form these 

 are the so-called "fixed connective- 

 tissue corpuscles," and bone corpuscles 

 while others merely wander or pass into 

 these spaces, and are called ' ! wandering 

 cells," or "leucocytes"; but the latter 

 x lg. 21o. are mere jy lymph-corpuscles, or colourless 



Origin of lymphatics from the central tendon of the blood-corpuscles which have passed out of 

 diaphragm stained with nitrate of silver, s, the the blood-vessels into the origin of the 

 juice-canals, communicating at x with the lym- lymphatics. These cells exhibit amoeboid 

 phatics ; a, origin of the lymphatics by the couflu- movements. These spaces communicate 

 ence of several juice-canals. w ith the small tubular lymphatics the 



so-called lymph- capillaries (L). The spaces lie close together, where they pass into a lymph- 

 capillary (a). The lymph-capillary, which is usually of greater diameter than the blood- 

 capillary, generally lies in the middle of the space within the capillary arch (B). The finest 

 lymphatics are lined by a layer of delicate, nucleated, endothelial cells (e, e), with characteristic 

 sinuous margins, whose characters are easily revealed by the action of silver nitrate (fig. 217, L). 

 This substance blackens the cement-substance which holds the endothelial cells together. 

 Between the endothelial cells are small holes, or stomata, by means of which the lymph-capil- 

 laries communicate (at *) with the juice-canals. 



