88 



ELEMENTS OF HISTOLOGY. 



[Chap. XI. 



capillaries and lymphatic vessels, represents the natural 

 current of lymph irrigating the tissues. 



115. Lymph cavities. In some places the lym- 

 phatic vessels of a tissue or organ are possessed of, or 

 connected with, irregularly-shaped large sinuses, much 

 wider than the vessel itself ; these cavities are the 

 lymph sinuses, and their wall is also composed of a 

 single layer of more or less polygonal endothelial 

 plates with very sinuous outlines. Such sinuses are 

 found in connection with the subcutaneous and sub- 

 mucous lymphatics, in the diaphragm, mesentery, liver, 

 lungs, &c. On the same footing i.e., as lymph 

 sinuses stand the comparatively large lymph cavities 

 in the body, such as the subdural and subarachnoidal 



spaces of the central 

 nervous system, the 

 synovial cavities, the 

 cavities of the tendon- 

 sheaths, the cavity of 

 the tunica vaginalis 

 testis, the pleural, 

 pericardial, and peri- 

 toneal cavities. In 

 batrachian animals, 

 e.g., frogs, the skin all 

 over the trunk and 

 extremities is sepa- 

 rated from the sub- 

 jacent fasciae and 

 muscles by large bags 

 or sinuses the sub- 

 cutaneous lymph sacs. 

 These sinuses are shut 



off from one another by septa. Between the trunk 

 and the extremities, and on the latter, the septa 

 generally occur in the region of the joints. In 

 female frogs in the mesogastrium smaller or larger 



Fig. 54. Stomata, lined with Germi- 

 .nating Endothelial Cells, as seen 

 from the Cisternal Surface of the 

 SeptumCisternse Lymphaticse Magnae 

 of the Frog. (Handbook.) 



