ANATOMY OF THE LACTEAL AND LYMPHATIC VESSELS. 277 



The course of the lymphatics is generally direct. As they pass toward 

 the great trunks by which they communicate with the venous system, they 



FIG 84 Superficial lym- Fia. So. Deep lymphatics of the skin of the FlG 86 _ game finger, lat- 



phaiics of the skin of finger (Sappey). era i view, showing lym- 



the palmar surface of 1, 1, deep net-work of cutaneous lymphatics ; phatic trunks connected 



the finger (Sappey). 2, 2, 2, 2, lymphatic trunks connected with with the superficial net- 



this net-work. * work (Sappey). 



present a peculiar anastomosis with the adjacent vessels, called anastomosis 

 by bifurcation ; that is, as a vessel passes along with other vessels nearly 

 parallel with it, it bifurcates, and the two branches pass into the nearest ves- 

 sels on either side. These anastomoses are quite frequent, and they generally 

 occur between vessels of equal size. In their course, the vessels pass through 

 the so-called lymphatic glands. 



A notable peculiarity in the lymphatic vessels is that they vary very little 

 in size, being nearly as large at the extremities as they are near the trunk. 

 In their course, they are always much smaller than the veins and do not pro- 

 gressively enlarge as they pass on to the great lymphatic trunks. The largest 

 vessels that pass from the skin are -fa to -fa of an inch (1 to 2 mm.) in diame- 

 ter, and the larger vessels, in their course, have a diameter of ^ to -J of an 

 inch (2 to 3 mm.). As in the case of the smallest lymphatics of the primi- 

 tive plexuses, the elasticity of the walls of the vessels renders their diame- 

 ter greatly dependent upon the pressure of fluid in their interior. Many 

 anatomists have noticed that vessels which are hardly perceptible while emp- 

 ty are capable of being dilated to the diameter of half a line (about 1 mm.) 



