204 RESPIRATION, BLOOD, AND EXCRETION 



spaces, however, form a sort of mesh, or net, the parts of 

 which join, forming larger vessels, and finally all the 

 lymph is collected into two large vessels which open 

 into veins. Thus there is the lymphatic circulation which 

 differs from that of the blood in several ways. (1) There 

 is no special organ for forcing the lymph along, the circula- 

 tion depending mainly upon the movement of the muscles. 



Figure 219. — Superficial Lymphatics of Arm and Hand. 



(2) The lymphatic vessels are imperfect in the beginning, 

 being only irregular spaces. (3) The lymph contains 

 no red corpuscles and only a few white corpuscles. 



Cuts. — Since every part of the body inside the skin is 

 traversed by blood vessels, we cannot injure any part 

 without breaking at least some of the blood vessels. A 

 small cut causes the blood to flow only from capillaries, 

 and it flows slowly and in small quantities. If a vein is 

 cut, the blood will be dark in color, and will flow in larger 

 quantities, but steadily. A severed artery sends out 

 bright red blood in waves corresponding to the beat of 

 the heart. To stop the flow of blood from a vein, com- 

 press the vein beyond the cut ; from an artery compress 

 the artery between the cut and the heart. In either case 

 remain quiet to aid the blood to form a clot. 



Exercise. — The object of a circulatory system and of a 

 circulatory fluid is to supply every cell in the body with 



