142 ANATOMY FOR NURSES. [CHAP. XII. 



These united lymph vessels form very irregular labyrinths, 

 communicate freely with one another, and are altogether wider 

 than the blood capillaries. They form the link between the 

 lymph in the tissues outside pf themselves and the regular 

 lymphatic vessels into which they open. 1 



FIG. 101. A SMALL PORTION OF A LYMPHATIC PLEXUS. Magnified 110 diam- 

 eters. (Ranvier.) L, lymphatic vessel with characteristic endothelium ; (7, cell 

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



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 to the larger lymphatics, and from these 

 into the veins, and obstruct the flow of anything in the oppo- 

 site 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 stomata into the lymphatics, and the fluid which 

 moistens their surfaces is really lymph and not serum. 



