VACCINATION 445 



a "breaking out" (eruption) of the skin. Smallpox 

 belongs to the eruptive diseases ; the sores, when they heal, 

 leave the "pock" marks that give the disease its name. 

 Up to the year 1800 almost everybody expected to have 

 smallpox; few seemed to have sufficient resisting power to 

 ward off the disease. The loss of life in smallpox epi- 

 demics was enormous : between the years 1700 and 1800 

 probably 600,000 persons, on the average, died of the 

 disease every year. But the practicing of vaccination 

 and the progress made in sanitary science have combined 

 to reduce the deaths fj-om the disease to comparatively 

 small numbers. 



Vaccination for smallpox was preceded by inoculation, which may 

 be defined as artificial infection. Inoculation consisted in putting 

 some of the ''matter" from the eruptions of a smallpox patient under 

 the skin of a person who was well. The person inoculated chose to 

 have the disease when he was prepared for it, rather than when he was 

 not prepared. He usually had the disease in a mild form, and then 

 was immune for life. The method of inoculating well persons came 

 from China to Constantinople (we do not know when); from Con- 

 stantinople it spread, in about 1720, to Western Europe and to Amer- 

 ica. One disadvantage of this early method of inoculation was that 

 the persons treated could give the disease to others, hence they had to 

 be isolated, or kept apart. There were also some serious accidents 

 in inoculation, because men did not know of the existence of germs, and 

 therefore did not know the meaning of sanitary cleanliness. If the 

 "matter" introduced into the body of the well person was infected 

 with other germs, or if the instruments used were not clean, the person 

 inoculated "caught" other serious diseases. 



435. Vaccination. The discovery of vaccination (vacca 

 means "a cow") by Jenner came in 1796. Jenner took 

 the "matter" formed in cowpox (smallpox of the cow), 



