361.  Contusion and Bruises.  An injury to the soft tissues, caused by a blow from some blunt instrument, or a fall, is a contusion, or bruise.  It is more or less painful, followed by discoloration due to the escape of blood under the skin, which often may not be torn through.  A black eye, a knee injured by a fall from a bicycle, and a finger hurt by a baseball, are familiar examples of this sort of injury.  Such injuries ordinarily require very simple treatment.

The blood which has escaped from the capillaries is slowly absorbed, changing color in the process, from blue black to green, and fading into a light yellow.  Wring out old towels or pieces of flannel in hot water, and apply to the parts, changing as they become cool.  For cold applications, cloths wet with equal parts of water and alcohol, vinegar, and witch-hazel may be used.  Even if the injury is apparently slight it is always safe to rest the parts for a few days.

When wounds are made with ragged edges, such as those made by broken glass and splinters, more skill is called for.  Remove every bit of foreign substance.  Wash the parts clean with one of the many antiseptic solutions, bring the torn edges together, and hold them in place with strips of plaster.  Do not cover such an injury all over with plaster, but leave room for the escape of the wound discharges.  For an outside dressing, use compresses made of clean cheese-cloth or strips of any clean linen cloth.  The antiseptic corrosive-sublimate gauze on sale at any drug store should be used if it can be had.

Wounds made by toy pistols, percussion-caps, and rusty nails and tools, if neglected, often lead to serious results from blood-poisoning.  A hot flaxseed poultice may be needed for several days.  Keep such wounds clean by washing or syringing them twice a day with hot antiseptics, which are poisons to bacteria and kill them or prevent their growth.  Bacteria are widely distributed, and hence the utmost care should be taken to have everything which is to come in contact with a wounded surface free from the germs of inflammation.  In brief, such injuries must be kept scrupulously neat and surgically clean.

[Illustration:  Fig. 156.—­Dotted Line showing the Course of the Brachial Artery.]

The injured parts should be kept at rest.  Movement and disturbance hinder the healing process.

362.  Bites of Mad Dogs.  Remove the clothing at once, if only from the bitten part, and apply a temporary ligature above the wound.  This interrupts the activity of the circulation of the part, and to that extent delays the absorption of the poisonous saliva by the blood-vessels of the wound.  A dog bite is really a lacerated and contused wound, and lying in the little roughnesses, and between the shreds, is the poisonous saliva.  If by any means these projections and depressions affording the lodgment can be removed, the poison cannot do much harm.  If done with a knife, the wound would be converted, practically, into an incised wound, and would require treatment for such.