Life of Dv, J enner. l55 



mics. How else did the terms chicken-pox and swine-pox creep 

 into our language. ** In Bengal," says Dr. Jenner, (p. 237) 

 *' the poultry are subject to an epidemic eruption, which 

 Jjills them by hundreds. The natives have only one name for 

 this disease and the small-pox, gootry.'^ ** A traditionary 

 account is handed down to us by the Arabian physicians, 

 that the small-pox was originally derived from the camel." 

 (P. 522 ; Letter from Dr. Jenner to H. R. H. the Duke of 

 Clarence.) We have an account at p. 238, of some children 

 who were inoculated at Madrid in Marcli 1804, by order of 

 the king of Spain, with a goat-pock. We are not favoured, 

 however, with the result of the test-trials, or contra- proofs 

 as they are called by the professor Heydeck. 



*' It seems certain, then," says Dr. Baron (p. 243), " that 

 there are at least four animals, namely, the horse, the cow, 

 the sheep, and the goat, which are affected by a disorder 

 communicable to man, and capable of securing him (to a 

 certain degree at least) from what appears to be a ma- 

 lignant form of the same disease." Into the many illustra- 

 tions given of this position we cannot here, of course, enter ; 

 but our readers will gather from the remarks now offered 

 some ideas of the reasoning by which Dr. Jenner was in- 

 duced to experiment on the influence of cow-pox. The sum 

 of his doctrine was briefly this. He not only considered 

 small-pox and cow-pox as essentially the same disease, but 

 he imagined ** that the former was only a malignant variety 

 of the latter, the parental root being the cow-pox." (p. 357.) 

 This notion of the identity of cow-pox and small-pox, so fre- 

 quently urged by Jenner, and so pointedly marked by his 

 phrase variolcz vaccince^ has been much questioned in later 

 times, and a few observations upon it may not be misplaced. 

 Diseases that mutually produce each other are clearly 

 referrible to the same source. The identity of swine-pox 

 and small-pox is, therefore, generally admitted. Dr. Adams, 

 however, entertained the opinion, that by successive inocu- 

 lations with a mild matter, a permanent modification of 

 small-pox might ultimately be obtained, and he actually 

 persuaded himself that he had succeeded in the attempt. 

 He called the disease pearl-pox, and it appears to have 

 been intermediate between cow-pox and distinct small-pox. 

 Some notion of the same kind probably influenced Jenner, 

 when, in 1789, he inoculated, his eldest son with the matter 

 of swine-pock. The child took a mild and modified disease, 

 and i-esisted the future action of variolous matter. Dr. 

 Jenner seems to have retained the same opinion as late as 



