ORIGIN OF THE LYMPH-CHANNELS. LYMPHATICS. 361 



ORIGIN OF THE LYMPH-CHANNELS. LYMPHATICS. 



Development by Means of Secretory Spaces. Within the supporting sub- 

 stances (connective tissue, bone) numerous star-shaped or polymorphous spaces 

 are found that are connected with one another by means of delicate tubular 

 processes. This system of communicating spaces contains the cellular elements 

 of the tissues. The cells, however, by no means completely fill the spaces, 

 an interval often existing between the cell-body and the wall of the space, 



FIG. 130. Origin of the Lymph-channels: I, from the central tendon of the rabbit (semi-diagrammatic); s, 

 secretory spaces, communicating with the lymphatic at x; a, commencement of the lymphatic fromlthe 

 confluence of secretory spaces. II, perivascular lymphatics. III. lymph-stomata. 



and varying in size, in accordance with the state of motility of the protoplasmic 

 cells. These spaces are the so-called secretory spaces, or secretory canals, and 

 they represent the commencement of the lymphatics. As adjacent spaces inter- 

 communicate, the propulsion of the lymph is provided for. The eel 

 the secretory spaces are capable of ameboid movement. In part they remain 

 permanently in their spaces (fixed connective-tissue cells, bone-corpuscles); in 

 part they are capable of engaging in active migration through the secretory canal- 



