59 3 SCIENCE PROGRESS 



The oldest and still the greatest prophylactic measure is 

 vaccination against small-pox, and from this the whole method 

 takes its name. Before this was introduced prophylactic in- 

 oculation against small-pox with matter from small-pox pustules 

 was for some time in use. This was a common practice in the 

 East long before it was introduced into England. It was 

 observed in Constantinople by Lady Mary Wortley Montagu, 

 wife of the British Ambassador, who subjected her own son to it. 

 She introduced the method into England in 172 1, in the teeth of 

 bitter opposition, and her grandson during a severe epidemic 

 made extensive use of it with brilliant results. He inoculated 

 over two thousand persons, of whom only three died. Direct 

 inoculation, however, was open to this serious objection — that 

 although the patient himself suffered only from a mild attack, 

 which was followed by immunity, he could none the less convey 

 the infection in a virulent form to others ; and the practice was 

 finally prohibited by law. 



In 1780 the attention of Edward Jenner was drawn to a 

 vesicular disease of the udders of cows which sometimes infected 

 the hands of dairy workers, who were found to be afterwards 

 immune to small-pox. Instances are recorded of farmers who 

 successfully inoculated their families. Jenner investigated the 

 subject, and in 1796 inoculated a boy with cow-pox and after- 

 wards with small-pox, to which he proved immune. He published 

 his results in 1798, a long controversy followed, and in about 

 1800 the systematic practice of vaccination began. The results 

 were immediately visible : in London in the two last decades of 

 the eighteenth century the mortality from small-pox was 17,867 

 and 18,477 respectively, while in the first two decades of the 

 nineteenth it fell to 12,534 and 7,856. 1 



It is remarkable, in view of the wide employment and success 

 of vaccination, that the causal organism of both cow-pox and 

 small-pox is still not certainly determined, so that it is not 

 possible to state definitely whether they are identical or not. 

 It is probable that they are descended from a common origin, and 

 that the organism is modified by passage through a refractory 

 animal. The great principle established by Jenner is that it is 

 possible, by using a modified materies morbi, to confer artificial 

 immunity to an infective disease. 



A century elapsed from the date of Jenner's first observations 



1 Councilman, article "Small-pox," Osier's System of Medicine. 



