120 ANATOMY FOR NURSES. [CHAP. XI. 



united lymph vessels form very irregular labyrinths, communi- 

 cate freely with one another, and are altogether wider than the 

 blood capillaries. They form the link between the lymph in 



FIG. 84. A SMALL PORTION OF A LYMPHATIC PLEXUS. Magnified 110 diam- 

 eters. (Ranvier.) L, lymphatic vessel with characteristic epithelium; C, cell 

 spaces of the connective tissue abutting here and there against the lymphatics. 



the tissues outside of themselves and the regular lymphatic 

 vessels into which they open. 1 



In structure, the larger lymphatic vessels closely resemble 

 the veins, except that their walls are somewhat thinner and 

 more transparent, and are more abundantly supplied with 

 valves. The valves are constructed and arranged in the same 

 fashion as those of the veins, but follow one another at such 

 short intervals, that, when distended, they give the vessel a 

 beaded or jointed appearance. They are usually wanting in 

 the smaller networks. The valves allow the passage of mate- 

 rial from the smaller lymphatics to the veins, and obstruct 

 the flow of anything in the Apposite direction. The lymphatics 

 do not carry to the tissues. /Their office is to carry away from 

 the tissues into the veins all the material the tissues do not need. 



1 The serous cavities may be regarded as expanded lymph spaces, as they 

 open by means of their stpmata into the lymphatics, and the fluid which 

 moistens their surfaces is really lymph and not serum. 



