192 ELEMENTARY BIOLOGY 



distribution of many kinds of bacteria, however, it is wise to 

 look after even small cuts and scratches. 



The festering of sores and cuts, which was formerly looked 

 upon as a normal and necessary condition of healing, we now 

 know to be the result of the action of various kinds of 

 microbes, some of which, at least, produce serious blood 

 poisons (see p. 195). To prevent the festering of a sore, and 

 to prevent the invasion of the body by more injurious micro- 

 organisms, it is well to treat every cut with an antiseptic, or 

 sterilizing, solution, such as a solution of carbolic acid or 

 bichlorid of mercury, or with tincture of iodin or alcohol. 

 The cut should then be covered with clean cotton or gauze, 

 to prevent the entry of microbes later. 



With larger wounds it is sometimes necessary to use 

 special means to stop the bleeding. When the flow of blood is 

 too strong, the adhesion of the clot to the sides of the wound 

 may be prevented. When the flow is from an artery (which 

 may usually be recognized by the pulsation), the limb should 

 be tied above the cut ; that is, on the side toward the heart. 

 When the flow is from a vein, the attempt to stop the flow 

 should be made on the side away from the heart. 



222. Nose bleeding. In very many cases nose bleeding may 

 be stopped by snuffing cold water. The old-fashioned remedy 

 of dropping a key down the person's back rested on the fact 

 that the chill causes the capillaries to contract. A piece of ice 

 applied for a few moments to the back of the neck will be 

 more likely to have the desired effect. Where bleeding con- 

 tinues after such a simple treatment, it is probable that some 

 small artery has been broken, or that the person's blood is 

 incapable of clotting. An astringent is then advisable. Powdered 

 alum, tannin, or ferric chlorid may be applied on a tuft of cotton. 

 These substances cause the fine blood vessels to contract and 

 thus stop the bleeding. In extreme cases a physician will use 

 adrenin, an extract of the capsules lying above the kidneys 

 (see p. 189). 



