SUMMARY 455 



of getting the gas into a room is to sprinkle 40% ' ' forma- 

 lin" solution (a solution containing formaldehyde) upon 

 sheets placed in the room to be disinfected. The sheets 

 may be hung upon clothes lines. The room should be 

 closed tightly for several hours to give the disinfectant 

 time to complete its work. Separate articles may be 

 disinfected by placing them in a trunk, between cloths 

 wet with formalin solution. 



Many accidents occur every year because some people 

 keep disinfectants in the family medicine closet, or have 

 them about the house, without a warning label. All such 

 substances should be kept by themselves, in a locked case, 

 and should be distinctly marked. They should also be 

 colored by the addition of a tiny amount of some bright 

 dye, so that no one will mistake them for something else. 



439. Summary. Contagious diseases are caused by germs. Germs 

 may be bacteria or protozoa. The science of germs is bacteriology. 



Hygiene is the science of keeping the body in good health; sanita- 

 tion deals especially with the health of the community. 



Germs grow in the body because they find favorable conditions 

 there. The body's defenders against germs that are in the blood are 

 the white corpuscles and the germicides. 



The effect of germs is due to the toxins which they produce. From 

 the time we are exposed to a disease until we "come down" with it, the 

 germs are multiplying; this is the incubation period. 



Germs can be destroyed, outside of the body, by cleansing the 

 body and its surroundings, by removing dust, by letting light and air 

 into our houses, and by disinfectants. 



Disinfection is the destruction of harmful germs. Fumigation is 

 disinfection by gases. 



Flies hatch in filth, visit dirty places, and infect our surroundings 

 and our food. Houses should be screened against them, those inside 



