1902.] The Inter-relationship of Variola and Vaccinia. 121 



of it. Extreme care has been taken, however, to make the number of 

 the dots bear fairly accurately a general proportion to the density of 

 the degeneration, and the same proportion in one drawing as in 

 another. 



" The Inter-relationship of Variola and Vaccinia." By S. Monck- 

 ton Copeman, M.A., M.D. Cantab., F.E.C.P. Communicated 

 by Loed Lister, F.B.S. Eeceived November 13, — Eead 

 November 27, 1902. 



The term " variolse vaccinae " employed by Jenner, as a synonym 

 for cow-pox, has been generally accepted as affording evidence that 

 in so naming this disease, " small-pox of the cow," he was desirous of 

 placing on record his belief that cow-pox, or vaccinia, was intimately 

 related to human small-pox, if indeed it were not directly derived 

 from it. 



This theory, however, appears to have found but scanty favour in 

 Jenner's day, and even at the present time the value of the practice 

 of vaccination is, by some, impugned on the plea that inoculation of 

 one disease — cow-pox—could not be expected to exert any really pro- 

 tective influence against the ravages of small-pox — a disease considered 

 by them of totally different origin. 



In the hope of obtaining definite information on the subject, many 

 observers, during the long period which has elapsed since the intro- 

 duction of vaccination, have set themselves the task of attempting to 

 solve, by experimental methods, the problem of the true relationship 

 of vaccinia to variola. 



These attempts have been, for the most part, directed to the 

 possibility of giving rise to cow-pox by the introduction, in one or 

 another manner, of the virus of small-pox into the system of the 

 bovine animal. In the great majority of such attempts, which have 

 been much more numerous than is generally supposed, the results 

 have been entirely negative, although so numerous have been the 

 experimenters, who from time to time have attacked the problem, 

 that the total number of instances in which an apparently successful 

 result has been obtained, is now considerable. 



So far as I am aware, the first recorded experiments are those of 

 Gassner of Gunsberg, who, in 1801, succeeded, after no less than ten 

 fruitless attempts, in directly variolating a cow with small-pox virus. 

 The lymph thus obtained was employed for the vaccination of four 

 children, from whom other seventeen were subsequently vaccinated. 

 None of these exhibited any signs of small-pox. 



