HEALTH AND DISEASE 417 



ened germs of that disease are sometimes 'injected into 

 the body. 



Vaccination (vacca, cow) was discovered in 1796 by 

 Jenner. He found at that time that if pus from sores 

 found on cows, suffering from the disease cowpox, was 

 injected into the human body, the person was pro- 

 tected from smallpox. 



The methods at first employed in securing this pus, 

 or vaccine, were very crude and the results from its 

 use were sometimes disastrous. It is now secured by 

 injecting into a healthy young cow germs which give 

 the cow the disease known as cowpox. This results 

 in the formation of sores from which pus is taken. 

 It is preserved in small tubes and is injected into the 

 skin when a person is vaccinated. If this l ' takes, ' ' the 

 person has a mild disease which produces in the blood 

 germicides for the smallpox germ. Vaccination is now 

 being successfully carried out against typhoid fever. 

 This is done in cases of epidemics in cities, and also 

 in armies. 



Medicines. Very few drugs can be used to destroy 

 germs. Those which are successful are in most cases 

 also destructive to the tissues. Physicians give medi- 

 cines to aid the body in the destruction of the germs, 

 the substances for which must come from the body 

 itself. In some cases medicines are administered to 

 produce immediate, but only temporary, relief. This 

 does not cure the disease, but it is often an advantage. 

 To accomplish such relief drugs are sometimes used to 



