Variola : Cowpox. 343 



The rational conclusion is, that while there is ever}' indication 

 of a primal identity of the two diseases, and indeed of all forms 

 of variola, as shown by a disposition of the virus from one genus, 

 when inoculated upon a totally different genus, to show some in- 

 dication of the characteristic eruption of the latter, yet the 

 generic type, which comes from the long-continued growth in the 

 one class of animal, becomes so fixed, that it cannot be overcome 

 at once, and sometimes apparently not at all, by transferring it to 

 an animal of another class. 



If the unfortunate results obtained by Martin, Reiter, and 

 Chauveau, are insufficient to deter from the use of smallpox 

 lymph which has been passed through the cow, the long experi- 

 ence with humanized vaccine, which in its inoculation from man 

 to man for a century has shown no tendency to revert to small- 

 pox virus should be a sufficient warning against such dangerous 

 optimism. 



No deduction can be safely drawn from the comparative mild- 

 ness of most of the cases caused by reinoculation from cow or 

 horse to man, inasmuch as that all forms of variola can be 

 rendered less severe by resorting to inoculation, which was ex- 

 tensively practised to limit the ravages of smallpox before the 

 days of vaccination, and is still largely resorted to in the case of 

 sheeppox in Europe. In each of these diseases the mortality 

 can easily be reduced to 2 per cent, instead of the 20 to 50 per 

 cent which are lost when the disease is contracted casually. 



As occurring casually, cowpox like horsepox is rare. Yet in 

 Denmark, a dairying country, 1,037 cases were reported in 

 1877-8, and 878 cases in 1888-9. I have found some outbreaks 

 explainable, through the existence of vaccinations in the families 

 of the milkers, and Bollinger says that in Germany, most out- 

 breaks take place in spring, the time when children are vaccinated. 

 He should have added that this is the usual time of parturition 

 in the cow, the time when primipara are first subjected to the 

 danger from the hands of the milker, and when the cow from the 

 non-infected district is brought into an infected stable for the 

 season's milking. In a dairying district in Tompkins Co., N.Y., 

 the affection appeared every spring, in the same barns, in heifers 

 with their first calf and in newly bought cows. All older cows, 

 bulls, steers and tin impregnated heifers escaped. 



