370 SOURCE OF THE LYMPH-CELLS. 



Muscular activity causes increased lymph-production, as well as a 

 more rapid escape of the lymph. The tendons and fasciae of the skeletal 

 muscles, which possess numerous small stomata, absorb lymph from the 

 muscular tissue. With alternate contraction and relaxation of these 

 fibrous tissues, their lymph-ducts suck themselves full and propel the 

 lymph onward. Even passive movements are effective in this direction. 

 If solutions are injected beneath the fascia lata, they can be propelled 

 onward by passive movements, contraction and relaxation, into the 

 thoracic duct. 



SOURCE OF THE LYMPH-CELLS. 



A considerable portion of the lymph-cells are derived from the lymph- 

 glands, out of which the lymph-stream washes them into the efferent ves- 

 sel. Therefore it happens that the lymph-stream, after passing through 

 the lymph-glands, is always found richer in lymph-cells. Within the 

 lymph-glands there are large and small lymphocytes, the -latter being 

 the daughter-cells of the former, and arising by mitosis. In addition, 

 new leukocytes are constantly migrating from the blood-capillaries of 

 the follicular bands into the reticulum. The lymphatic follicles permit 

 cellular elements to enter through the meshes of their limiting layer into 

 the adjacent small lymph- vessels. 



A second seat of lymph-cell production is found in the organs contain- 

 ing adenoid tissue as a basis, in the meshes of which lymph-cells are found 

 in large number, such as the entire mucous membrane of the intestinal 

 tract, the bone-marrow and the spleen. The cells reach the radicles of 

 the lymph- vessels in these organs by ameboid movement. 



Just as the lymph-cells reach the circulation through the large trunks 

 and are there encountered as white blood-corpuscles, so, likewise, 

 numerous leukocytes migrate in turn from the blood-capillaries into the 

 lymph- vessels, especially in their small beginnings, and partly by active 

 ameboid movement, partly by being forced by filtration-pressure exerted 

 by the blood-column. In rare cases even a return movement of lymph- 

 cells from the lymph-spaces into the blood-vessels has been observed. 



Also particles of cinnabar or milk-globules introduced into the blood reach 

 the lymph- vessels from the blood-capillaries in a short time; the nerves of the 

 vessels having no influence in this condition. In case of venous stasis, in analogy 

 with the processes attending diapedesis, this passage takes place more freely than 

 when the circulation is unembarrassed. Inflammatory changes in the vessel- 

 wall also favor the passage. The vessels of the portal system prove especially 

 permeable. 



New lymph-cells result also through multiplication by division of the 

 lymph- corpuscles, and likewise of the so-called fixed connective-tissue 

 cells, as has been demonstrated with certainty especially in the pres- 

 ence of inflammation of certain organs. If irritants which excite inflam- 

 mation are applied to the excised cornea, kept in a moist chamber, 

 a large increase in the wandering cells in the anastomosing lymph- 

 passages of the cornea will be noted ; and as, in the inflamed cornea, the 

 corneal cells permit the recognition of a reproduction of their nuclei by 

 division, the conclusion is probably justified that a division of the corneal 

 corpuscles (fixed connective-tissue cells) is responsible for the increase 

 in the wandering cells. 



That a new-formation of leukocytes must take place by division, as well as 

 by the setting free of divided connective-tissue cells, is shown by their often 



