HEALTH AND WELL-BEING 21 



The microscope is to the bacteriologist very much what 

 the telescope and its accessories are to the astronomer. As- 

 certain the literal meaning of the terms (a) microscope ; (6) 

 telescope. 



2. Fortunately the number of kinds of germs which cause 

 disease in persons is relatively small. The symptoms of 

 the ailment and the degree of danger to the life of the patient 

 vary with the kind of germ, its vigor, and the state of 

 health of the person. In some cases the development of 

 the germs after their introduction into the body can be 

 checked or prevented ; in other cases the disease must run 

 a course dependent upon the life changes through which 

 the germ passes. In such cases whether the patient lives 

 or not depends in large measure upon his powers of endur- 

 ance. Explain the weakness of body incident to long-con- 

 tinued sickness. Aside from feeling a need for it, why is it 

 better when sick to keep quiet, even remaining in bed ? 



3. When persons recover from a germ disease the sys- 

 tem often seems to remain for a considerable period of time 

 in a condition unfavorable to any new development of the 

 kind of germs that caused that disease. Ill effects may not 

 be experienced from them for a long time. One is then 

 said to be immune to that particular disease. 



A like condition is often brought about under direction of 

 a physician by processes of inoculation, or vaccination. There 

 is introduced into the system a specially prepared virus, or 

 serum. This causes a mild form of the ailment, and leaves 

 the patient for a time immune to any severe attack, and pos- 

 sibly to any attack at all of that disease. 



The life products of the disease germs within the human 



