310 THE DISEASES AND DISORDERS OF THE OX. 



The first recorded epidemics of small-pox occurred in the 

 sixth century. Early in the eighteenth century the disease 

 was deprived of a great deal of its terrors by reason of the 

 practice of inoculation, which was at that time introduced into 

 this country by Lady Mary Wortley Montague, who had seen 

 the efficacy of the method in Constantinople, to which place it 

 had been imported from Persia and China. In the latter half 

 of the same century a belief in the protective power of cow-pox 

 against variola seems to have been entertained in Gloucester- 

 shire. It is said that a schoolmaster named Plett, in HolsteiU; 

 vaccinated two cliildren in the year 1771 ; and it seems to be 

 established than an English farmer named Benjamin Jesty per- 

 formed the same operation on his wife and two sons in the year 

 1774. The value of vaccination was, however, first really proved 

 by Edward Jenner, whose first publication on this subject 

 appeared in 1798. 



In the ninety-one years which have elapsed since that date 

 the practice of vaccination as a preventive of small-pox has been 

 adopted throughout the whole civilised world. Experience has 

 shown that successful vaccination is as protective against sub- 

 sequent attacks of small-pox as an attack of that disease itself 

 is. Where vaccination is in vogue, small-pox has become 

 comparatively rare and unimportant. The protective influence 

 of the vaccine matter is not diminished by its continued trans- 

 mission from man to man. The immunity becomes less sure 

 as years pass by ; but if a person who has been vaccinated does 

 contract small-pox, the disease is as a rule mild, and but very 

 rarely fatal. The mortality among those suffering from small- 

 pox who have not been vaccinated has been found to be as much 

 as 37* per cent., whereas of those who had as many as four or 

 more vaccination marks the mortality was only 0*55 per cent.; 

 and even among those who were said to have been vaccinated 

 but had no cicatrix, the fatal cases were in the proportion of 

 only 23*67 per cent. These Fesults were obtained by Mr. 

 Marson, and represent an experience of twenty years at the 

 Small-pox Hospital in London, collected from an examination 

 of 5,000 cases. It has, however, been held that syphilis, 

 scrofula, and perhaps other diseases may possibly be imparted 



* In Seaton's account of Marson's work, I find 35 per cent, instead of 37. 



