Florence li. Sabin 195 



lial lining which bud off from previous lymphatic ducts, the original 

 ones coming from the endothelium of the veins. The development has 

 been traced by making injections along the lines in which the lymphatics 

 grow to the skin. In the neck the ducts grow toward the skin along 

 the jugular vein and come to the surface at three points; in the posterior 

 part of the neck, at the angle of the jaw and in the front of the neck. In 

 the posterior part of the body the ducts follow the femoral and its 

 branches and come to the surface first over the crest of the ilium, and 

 secondly in the inguinal region. From these points the ducts invade 

 the skin and form a primary plexus in the subcutaneous tissue and a 

 secondary one in the chorium. From the plexus in the chorium sprouts 

 grow outward into the center of the papillae. In their entire growth 

 the lymphatics follow the blood vessels. 



The lines of growth of the lymphatics to the various organs are along 

 the course of the aorta and its branches. For example, by injecting 

 into the edge of the wall of the aorta it is possible to inject the ducts 

 as they are entering the heart and the lungs. The early ducts to the 

 kidney are large and easy to olitain. By the time the pig is 4 cm. long 

 the ducts can be injected to the stomach wall and have grown between 

 the folds of the mesentery to the intestinal wall. Repeated injections 

 would probably show tlie growth of the ducts into the different layers 

 of the intestinal wall to their end in the central chyle vessel of the villi. 



