62 HUMAN BIOLOGY 



to life than a cut vein. Because of the toughness of the 



arteries, and because they are located close to the bones, 

 they are less likely to be cut than the veins, which are 

 softer and nearer the surface. The veins begin in capil- 

 laries and empty into the auricles ; the arteries begin at the 

 ventricles and empty into capillaries ; and there is a semi- 

 lunar valve at the origin of each artery. 



Cuts and Bruises. — i. Wash a cut under running water. 

 2. Stop the bleeding. The washing in cold water may do 

 this. Elevating an injured arm or leg will aid the blood 

 greatly in forming a clot at the opening. 3. Bandage 

 firmly with a strip of cloth and sew the end. Keep wet 

 the part of the bandage where the cut is ; this lowers the 

 temperature of the wound. It may be necessary to hold 

 a gaping wound closed with strips of surgeon's plaster 

 placed across the cut. A handkerchief folded first 

 into a triangle and then into a narrow bandage is often 

 useful. A cut artery may be known from a cut vein by 

 the brighter color of the blood, and by the flow being 

 stronger at each heart beat, while the flow from a vein is 

 uniform. Pressure to stop the flow of blood from an 

 artery should be applied between the cut and the heart; 

 but when the blood comes from a vein, the pressure should 

 be applied to the side of the cut farthest from the heart. 



Apply hot water immediately for several minutes to a 

 bruise. Either a bruise or a cut may be washed with a weak 

 solution of some antiseptic such as carbolic acid. After 

 washing a bruise it may be bound with a cloth soaked in 

 witch hazel or arnica. 



The Lymphatic System 



This system contains and conveys a liquid called 

 the lymph. It consists of lymph spaces, lymph tubes, 



