482 MAN CONTROLS HIS ENVIRONMENT FOR HEALTH 



Practical Exercise 16. Study the diagram on page 480. Show exactly why 

 the changes noted there occurred. 



Practical Exercise 17. What is the principle underlying the antitoxin 

 treatment for diphtheria? The Schick test? The Dick test? What is the 

 principle underlying vaccination against smallpox ? Against typhoid ? Against 

 boils? Explain. 



Practical Exercise 18. Make a list of all germ diseases that are now treated 

 by the passive method of immunity ; the active method of immunity. 



Positive health the goal. In the preceding pages we have seen 

 what science has done in combating disease. But many of these 

 diseases can be avoided simply by keeping in good condition. 

 If we keep our bodies in good physical condition through the use 

 of proper food, exercise, and sleep ; if we maintain a calm poise 

 and untroubled mind ; if we avoid worry and are cheerful in spite 

 of difficulties ; then we have gone far toward keeping well. We 

 now have the knowledge about communicable diseases and how to 

 fight them ; let us use this knowledge if it is necessary. But for 

 most of us health is something that can be earned, if we are willing 

 to pay the price. All that we have to do is to treat our bodies in 

 such a way that they will give us the most efficiency, for very few of 

 us have really poor bodily machines to start with. 



Self-Testing Exercise 



When poisons enter the body, the cells react by forming 



(1). The two kinds of acquired immunities are (2) 



and (3) . In the first, immunity is acquired through the 



use of (4) ; and in the second through the use of (5). 



The Schick test is used to determine whether a person is (6) 



to (7). This disease may be eradicated by the use of 



(8). Diseases that may be stamped out by the use of 



vaccination are : (9), (10), ......... (11), and 



(12). 



PROBLEM VII. HOW IS MALARIA CAUSED AND 

 TRANSMITTED? 



The cause of malaria. The study of the life history and the 

 habits of the Protozoa has resulted in finding many parasitic 

 forms, and the consequent explanation of some diseases. An 

 amoeba-like parasite, of which at least three species exist, causes 



