296 GENERAL SCIENCE 



Smallpox. Smallpox was, until the discovery of vaccination, one 

 of the most dreaded diseases on account of its loathsome appearance, 

 extreme contagiousness and disfiguring consequences. Until a little 

 more than a century ago the disease was a great scourge, for it 

 attacked nearly every one, the loss of life being enormous. At 

 one time a large percentage of people in England were pock-marked. 

 Smallpox was the most common cause of blindness. Instead of 

 occurring in epidemics, as now, the disease was present continuously. 



Smallpox is usually transferred from one person to another 

 through the air, but it may be carried by infected clothing and other 

 objects. The extreme contagiousness of this disease is due to the 

 longevity of the germ. A person suffering from smallpox must be 

 strictly quarantined and everything that has been about him 

 burned or disinfected. 



Vaccination. Dr. Edward Jenner of Berkeley, England, dis- 

 covered the principle of vaccination in 1798. 



The germs of smallpox grown in cattle cause a disease called 

 cowpox. After growing in the cow the germ is changed and weak- 

 ened so that it grows feebly in man, and has only a slight power 

 of producing disease. In vaccination the germs from an infected 

 cow are injected into the human body, where they grow and produce 

 the usual condition following vaccination. The body works up the 

 germicidal substance necessary to kill germs before they make much 

 progress in the body. After this the germicidal substance remains 

 in the blood ready to kill any smallpox germs which may enter 

 the body. This germicidal substance grows weaker and weaker, 

 and after a few years re-vaccination may be necessary for full pro- 

 tection from the disease. The safest way is to be vaccinated every 

 few years. If the germicidal substance is still strong in the blood, 

 the vaccination will not " take." Two successful vaccinations usually 

 protect against smallpox for life. Doctors, nurses, and attendants, 

 if successfully vaccinated, have lived in smallpox hospitals in 

 perfect safety. 



Practically all the accidents of vaccination can be prevented by 

 the selection of the proper vaccine and suitable care of the arm 

 after vaccination. The danger from vaccination has been greatly 

 exaggerated. It is indeed slight as compared with the danger of 



