ORIGIN OF COW-POX. 327 



In 1828 Dr. McMichael reported that several physicians in 

 Egypt had obtained similar results, and children were successfully 

 " vaccinated." 



In 1836 Dr. Martin, in America, inoculated the cow's udder with 

 variolous lymph, and by inoculating children produced an epidemic 

 of small-pox with fatal cases. In 1839 Reiter of Munich, after fifty 

 unsuccessful attempts, succeeded in producing a vesicle, and a child 

 inoculated from the vesicle contracted small-pox. 



In 1839 Dr. Thiele, after a number of unsuccessful attempts to 

 inoculate cows with variolous virus, succeeded in producing a vesicle 

 with the physical characters of the vaccine vesicle, and from it a 

 stock of lymph was raised from which over three thousand persons 

 were inoculated. Thiele's method was to inoculate the udder with 

 lymph, and to select for the purpose young cows which had recently 

 calved and had delicate skins. In England Ceely succeeded by 

 inoculating the vulva of a heifer. One of the punctures developed 

 into an enormous vesicle, which was undoubtedly variolous. His 

 assistant punctured his hand with the lancet which had been used 

 to open the vesicle, and febrile symptoms appeared, followed by an 

 eruption on the face, neck, trunk, and limbs, at first papular, then 

 vesicular, and finally pustular. The lymph was used in children, 

 and " vaccine " vesicles were produced. One child suffered from 

 vomiting delirium, and extensive roseola, but there was no eruption 

 in any other case. 



In 1840 Badcock of Brighton inoculated a cow successfully, and 

 later succeeded in variolating thirty-seven out of two hundred cows 

 upon which he experimented. 



In 1847 variolation of the cow was successfully performed at 

 Berlin, but the virus produced variola, and one of the children 

 inoculated died of confluent small-pox. 



In 1864 Chauveau inoculated seventeen animals with virulent 

 small-pox lymph. Very small papules resulted, and the virus from 

 the papules produced variola in a child, which was infectious to others. 

 Klein in this country until recently was uniformly unsuccessful. 

 Yoigt, Fischer, King, Eternod, Haccius, Hime and Simpson, have 

 all succeeded in inoculating cows and producing variola-vaccine. 



The results of these experiments have been very generally misin- 

 terpreted, and claimed by some as conclusive evidence of the identity 

 of cow-pox and small-pox. Instead of the vesicle being regarded as 

 the most attenuated form of variola, the experimenters are said to 

 have succeeded in producing cow-pox. 



It is quite true that they produced phenomena indistinguishable 



