STRUCTURE OF LYMPHATIC GLANDS. 201 



lymphatic system, and may, indeed, be regarded as nothing more 

 than exaggerated lymph spaces. In most parts of the endothelial 

 surface of serous cavities are a number of so-called stomata, or 



FK;. 87. 



Endothelium from serous surface without stomata (nitrate of silver). 



small apertures surrounded by a few cells, which differ from the 

 ordinary endothelial cells in every respect, and probably have 

 to control the passage of the fluid from the serous cavity into 



FIG. 88. 



Endothelium from serous surface with stomata surrounded with granular protoplasmic 



cells. 



the lymph vessels. These stomata may be regarded as the com- 

 mencement of the dense network of lymph capillaries, which 

 lie in the subserous tissue. 



