PREVENTIVE INOCULATION. 117 



in them was infectious to others, and unprotected persons coming in 

 contact with the inoculated were likely to get infected from them. The 

 latter result was largely avoided by the practice adopted by the Brah- 

 nians of inoculating all the inhabitants of a family or village at the 

 same time. The benefits secured under the above precautions were 

 considered far to outweigh the risks of inoculation. 



With the extension of smallpox westward the system of artificial 

 protection spread toward Europe through the intermediary of travelers 

 and merchants. The Arabs and Turks appreciated its benefits at an 

 early date. The slave dealers supplying the bazaars and harems 

 of Constantinople adopted the system to protect against disfigurement 

 their Circassian and other live stock. In the early part of the eight- 

 eenth century the method was made known to the English practitioners 

 by Lady Mary Wortley Montagu, the wife of the English ambassador at 

 Constantinople, who had her two children inoculated according to the 

 Turkish system. Curiously enough, it was soon afterward discovered 

 that a similar method was in practice among the peasants of some of 

 the districts in Wales and the Highlands of Scotland, and had long 

 been known there as 'buying the smallpox.' When inoculation was 

 given a more extensive trial it was found, in England as in the East, 

 that the effect of it was decidedly beneficial, but fraught with danger. 

 At first one in every fifty of those operated upon succumbed to the 

 consequences of inoculation. By improved methods the mortality was 

 gradually reduced to one in a thousand; but the most serious danger lay 

 in the spread of infection to healthy persons. The precaution of inocu- 

 lating whole groups of inhabitants at one time, or of keeping the in- 

 oculated apart from the healthy, as had been practiced by the Brahmans 

 ages ago, was overlooked, and the result was often disastrous to the 

 community. 



It was at this time that Jenner achieved great progress and threw 

 a vast amount of new light on the question. As is well known, he 

 started from a belief that existed in the west of England, that cowpox 

 was a bovine form of smallpox, and that the milkers who attended on 

 cows suffering from that disease and who became infected with the 

 eruptions on the teats and udders, passed through a mild illness, which 

 rendered them immune against smallpox. Jenner determined to put 

 this tradition to the test, and succeeded in establishing, by a few accu- 

 rate and well-planned experiments, a series of most important facts. 



He showed, first, that cowpox could be artificially given to the 

 cow by infecting it with virus from a smallpox patient, and that the 

 disease thus produced was transferable by inoculation from cow to cow. 



He showed further, that by having been bred in the tissues of the 

 cow, the virus lost its intense infective properties for man. When 



