PERSONAL AND CIVIC HYGIENE 



PROBLEM LVI 



A study of personal and civic hygiene. 



Note. Disease germs are bacteria, or sometimes protozoa, 

 that develop in the body and set free poisons. Nearly all that 

 attack us come from the bodies of sick people. Therefore, we 

 should endeavor to destroy all that come from such sources. 



I. HOW BACTERIA MAY ENTER THE BODY 



Materials. A dozen sterilized Petri dishes, containing nu- 

 trient gelatin. 



Observations. 1. See that they have been kept well cov- 

 ered. Label them 1 to 12. Set aside No. 1, labeled " not ex- 

 posed," then in a temperature of about 70 F. Examine it for 

 results after a day, two days, three days. 



2. Sweep a corner of the room, thus stirring up a little dust. 

 Open dish No. 2 and expose it to the air for half a minute. 

 Set it aside and observe it daily. 



3. Touch the gelatin of No. 3 with the tip of a lead pencil 

 which has previously been moistened in the mouth. Set it 

 aside and observe it daily. 



4. Touch the gelatin of No. 4 with the tips of the fingers, 

 that have not been recently washed in soap and water. Set it 

 aside and observe it daily. 



5. Moisten the gelatin of No. 5 with water. Set it aside 

 and observe it daily. 



6. Moisten the gelatin of No. 6 with milk. Set it aside 

 and observe it daily. 



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