METHODS OF INFECTION 161 



killed by bacteria. A very large portion of the infectious 

 diseases might be prevented if people knew more about 

 the ways by which germs enter the body and were more 

 careful to keep them out. It may help us to see how 

 germs get into the body if we study the way in which an 

 apple is protected against infection and by what means it 

 is infected. 



Experiment. To show how infection takes place. 



Materials: A sound apple. A decaying apple. Toothpicks. 



Method: (a) Make a small irregular hole through the skin of the sound 

 apple. Fill this with decaying pulp from the other apple, (b) Stick 

 a toothpick into the rot of the decaying apple and then stick it into 

 the sound apple, leaving it there, (c) Sterilize a toothpick by pass- 

 ing one end of it through a flame several times without allowing it to 

 take fire. Stick this end of the toothpick into the apple and leave it. 

 (d) In a four-inch area on the unbroken and unbruised skin of the 

 sound apple lay a little of the decaying apple pulp. Set the apple 

 away in a dark, warm place. 



Observation and Conclusion: Examine the apple daily until changes have 

 occurred in one or more of the places. Where does infection occur? 

 Explain what natural defense against infection the apple has, but how 

 conditions may arise in which decay results. 



Methods of infection. When we take germ diseases 

 the germs enter our bodies by means of the nose, mouth, 

 through body openings, or through a break in the skin. 

 They may be carried by means, of food, water, or even 

 through the air, and the germs usually are taken directly 

 from a person who has the disease. The most common 

 method of spreading disease is by sneezing or coughing, or 

 even breathing and talking close to the face of some one 

 else. If you have ever watched a person talk when in the 

 sunshine, you may have observed a constant spray of tiny 

 droplets which are forced out from the mouth. These 

 droplets are sprayed from two to three feet from the 



H.-WHIT. CIV. SCI. IN THE HOME II 



