624 ACTIVE IMMUNIZATION 



in Constantinople, observing this practice among the Turks, had her 

 own son and daughter inoculated and was largely instrumental in estab- 

 lishing the practice in Europe. 



As regards the prophylactic value of this method of inoculation in 

 England and continental Europe, statistics are incomplete, but the 

 literature of contemporary writers shows that protection was usually 

 complete. The induced disease was not, however, always mild, and not 

 infrequently assumed an unexpected virulence that not only proved dis- 

 tressing and even fatal to inoculated individuals, but also constituted a 

 source of infection to a community. While, therefore, the underlying 

 principles were sound, and while these early attempts at preventive 

 immunization mark an epoch in the history of medicine and of the world, 

 it was not until Edward Jenner made his investigations into a theory 

 held by farmers and by experimental evidence established it as true that 

 a satisfactory method of immunizing the body against smallpox was 

 introduced. 



The peasantry in various parts of Europe, and especially in England, 

 had generally observed that those who had had sores on their hands con- 

 tracted from similar lesions on the teats of cows, usually escaped small- 

 pox infection when the disease was epidemic in a community. In fact, 

 it is said that several farmers deliberately inoculated members of their 

 family with cowpox lesions and that these escaped smallpox. 



Edward Jenner was a physician practising in Berkeley, Gloucester- 

 shire, and frequently used the method of direct inoculation from a mild 

 case of smallpox among his patients. While a student he was impressed 

 with the traditions of cowpox vaccination, and finding that they were 

 largely true, determined to make' experimental tests. On May 14, 

 1796, he vaccinated a boy, James Phipps, with virus from a cowpox 

 lesion on the hand of a dairy maid, Sarah Nehnes, and on July 1st he 

 inoculated the same boy with pus from a smallpox patient without re- 

 sulting infection. In 1798 he furnished further proof that cowpox will 

 afford protection against smallpox by inoculating a child direct from a 

 vesicle on the teat of a cow, and continued the inoculation from arm to 

 arm through a series of five children, after which all were inoculated 

 with smallpox virus, without a single case developing. In the same year 

 he published "An Inquiry into the Causes and Effects of the Variolse 

 Vaccinse," illustrated by four plates, and within a year or two vaccina- 

 tion became general over Europe. 



Vaccination was introduced into the United States in July, 1800, by 

 Dr. Benjamin Waterhouse, Professor of Physic at Harvard University, 



