RESPIRATION AND EXCRETION 345 



Cuts, Bruises, and Burns. - In case the skin is badlv broken, 



9 \J 



it is necessary to prevent the entrance and growth of bacteria. 

 This may be done by washing the wound with weak antiseptic 

 solutions such as 3 per cent carbolic acid, 3 per cent lysol, or per- 

 oxide of hydrogen (full strength). These solutions should be ap- 

 plied immediately. A burn or scald should be covered at once 

 with a paste of baking soda, with olive oil, or with a mixture of 

 limewater and linseed oil. These tend to lessen the pain by keep- 

 ing out the air and reducing the inflammation. 



Summary of Changes in Blood within the Body. - We have 

 already seen that red corpuscles in the lungs lose part of their load 

 of carbon dioxide that they have taken from the tissues, replacing 

 it with oxygen. This is accompanied by a change of color from 

 purple (in blood which is poor in oxygen) to that of bright red (in 

 richly oxygenated blood). Other changes ta,ke place in other parts 

 of the body. In the walls of the food tube, especially in the small 

 intestine, the blood receives its load of fluid food. In the muscles 

 and other working tissues the blood gives up food and oxygen, 

 receiving carbon dioxide and organic waste in return. In the liver, 

 the blood gives up its sugar, and the worn-out red corpuscles which 

 break down are removed (as they are in the spleen) from the 

 circulation. In glands, it gives up materials used by the gland 

 cells in their manufacture of secretions. In the kidneys, it loses 

 water and nitrogenous wastes (urea). In the skin, it also loses 

 some waste materials, salts, and water. 



" The Effect of Alcohol on Body Heat.- -It is usually believed that 

 1 taking a drink ' when cold makes one warmer. But such is 

 not the case. In reality alcohol lowers the temperature of the 

 body by dilating the blood vessels of the skin. It does this 

 by means of its influence on the nervous system. It is, therefore, 

 a mistake to drink alcoholic beverages when one is extremely cold, 

 because by means of this more bodily heat is allowed to escape. 



" Because alcohol is quickly oxidized, and because heat is pro- 

 duced in the process, it was long believed to be of value in main- 

 taining the heat of the body. A different view now prevails as 

 the result of much observation and experiment. Physiologists 

 show by careful experiments that though the temperature of the 



