MAN'S PLACE IN NATURE 405 



and plants which are most destructive to mankind are 

 the ones which are so small that a microscope is needed 

 to find them. These animals and plants which have 

 become parasites to man produce many dangerous 

 diseases; and unless man is able to adapt himself to 

 the conditions which these parasites produce, or can 

 exterminate them by preventing their growth, they will 

 greatly hinder his progress or may even exterminate him. 

 In order to cope with these germs it is necessary for every 

 person to use all the knowledge which he possesses con- 

 cerning how to live so that he may keep himself clean, 

 healthy, and free from all germs. The blood of most 

 healthy people is able to kill nearly all disease germs as 

 fast as they get into their bodies. A person who is indul- 

 gent in several ways, or who is in other than good health, 

 cannot expect to be immune from the attacks of disease 

 germs. In order to have good health we should be as 

 regular as possible in our habits of rest, exercise, and times 

 for eating. The environment of the places where we rest 

 (sleep), exercise (work), and take our meals has a great 

 influence upon health. Since man is by nature endowed 

 with the capacity to select or to modify his environment 

 to some extent, it is necessary for him to make it as 

 favorable as possible for his existence. 



The way to change our environment is to -remove all 

 filth and decaying matter from our homes, have the rooms 

 properly ventilated, lighted, and heated, make our homes 

 attractive and beautiful inside and outside, with flowers 

 and decorations of various kinds, and see that the sources 

 of water supply such as springs and wells are properly 

 covered and protected from contaminating sources. 



280. Selecting a Home. Since so many people change 

 their location every year, it is very important that all 



