298 HUMAN PHYSIOLOGY CHAP, xix 



the body can throw off the disease ; but if not, the germs soon 

 gain a foothold, and fevers are the inevitable result. 



9. If the body will not take a certain disease, we say it is 

 immune to that disease. Natural immunity means that an ani- 

 mal cannot take a disease under any circumstances. Artificial 

 or temporary immunity may be brought about by antitoxins, 

 by vaccination, or by an attack of the disease. 



10. An abundance of good pure foods and pure water, an 

 adequate supply of pure fresh air, a sufficient amount of physi- 

 cal and mental exercise and rest, and good sanitary surround- 

 ings, tend to fortify the body against all diseases. 



11. Among the communicable diseases, many of which are 

 due to bacteria, are the following : consumption, diphtheria, 

 pneumonia, typhoid fever, cholera, lockjaw, malaria, grippe, 

 smallpox, scarlet fever, measles, mumps, whooping cough, cere- 

 bro-spinal meningitis, erysipelas, scarlatina, leprosy, chicken pox, 

 yellow fever, dysentery, anthrax, glanders, and relapsing fever. 



