AIR AND HEALTH 163 



fecting wounds or cuts iodine is much used ; while for use 

 on hands, a weak (i to 25 parts water) solution of carbolic 

 acid followed by scrubbing with green soap is safe and sure. 



Our body defenses against disease. Germ diseases 

 are usually caused by poisonous toxins. These are waste 

 materials given off by bacteria which act upon the individ- 

 ual like snake venom. Some people are very much more 

 resistant to these toxins than others, and therefore are less 

 likely to take " catching diseases." This resistance to or 

 defense against disease, when powerful enough to kill the 

 germs or offset the harm from toxins, produces an immu- 

 nity. Immunity may be natural, or it may be acquired in 

 the case of some diseases. This, for example, is done in 

 the case of diphtheria by means of antitoxin treatment, 

 and in the case of small pox and typhoid, by means of 

 vaccination. The theories underlying immunity will be 

 discussed more fully in the next book. Natural immunity, 

 however, may be increased by keeping the body in just 

 as good condition as possible. Proper habits of health as 

 suggested in the following paragraphs will assist greatly 

 in maintaining one's health. 



Air and health. We have already referred to the need 

 of oxygen. It is generally agreed at the present time that 

 we must have as much fresh air as possible, that our rooms 

 must be well ventilated, that porous clothes must be worn 

 so that the body can have a constant air bath, for the skin 

 under the clothes needs air as well as the parts exposed. 

 We have come to depend upon outdoor play and outdoor 

 sleeping as means of good health. We should always 

 practice good posture and acquire good breathing habits. 

 An excellent habit is that of morning exercise with the win- 

 dows thrown open. Remember that the lungs need exercise 



