The Blood and Lymph. 93 



The Lymphatic System. This system consists of ves- 

 sels and nodes (glands), the latter term nodes being sub- 

 stituted for glands, owing to the fact that these nodes do 

 not secrete, hence it would be wrong to term them 

 glands. The system might be compared to a line of 

 railway with the nodes as the stopping places. The nodes 

 are bean shaped and can be readily found in the animal 

 after death, e. g., between the lungs, on the inside of the 

 limbs, thighs and in the folds of the mesentery, when if 

 cut in halves the outer part is seen to be lighter in color 

 than the inner, they resemble a very small kidney in 

 fact; from these nodes are sent out leucocytes (white 

 blood cells). The vessels. originate as very small chan- 

 nels in the spaces between the cells of the body, especially 

 those of the serous membranes. Lymphatic vessels are 

 found in all parts of the body, those in the limbs possess 

 valves; these vessels unite and gradually form larger 

 vessels, until the thoracic duct is formed, which runs 

 along underneath the back bone and empties into the 

 vena cava. The lymphatic nodes are markedly affected 

 in many diseases, such as tuberculosis, etc. 



