212 EDWARD JENNER 



me by Dr. Pearson and Dr. Woodville, this appears to 

 be the fact; and what strikes me as still more extraordin- 

 ary with respect to those inoculated in London is the ap- 

 pearance of maturating eruptions. In the two instances 

 only which I have mentioned (the one from the inoculated, 

 the other from the casual, cow-pox) a few red spots ap- 

 peared, which quickly went off without maturating. The 

 case of the Rev. Mr. Moore's servant may, indeed, seem 

 like a deviation from the common appearances in the coun- 

 try, but the nature of these eruptions was not ascertained 

 beyond their not possessing the property of communicat- 

 ing the disease by their effluvia. Perhaps the difference 

 we perceive may be owing to some variety in the mode 

 of action of the virus upon the skin of those who breathe 

 the air of London and those who live in the country. That 

 the erysipelas assumes a different form in London from 

 what we see it put on in this country is a fact very gen- 

 erally acknowledged. In calling the inflammation that is 

 excited by the cow-pox virus erysipelatous, perhaps I may 

 not be critically exact, but it certainly approaches near 

 to it. Now, as the diseased action going forward in the 

 part infected with the virus may undergo different modi- 

 fications according to the peculiarities of the constitution 

 on which it is to produce its effect, may it not account 

 for the variation which has been observed? 



To this it may probably be objected that some of the 

 patients inoculated, and who had pustules in consequence, 

 were newly come from the country; but I conceive that 

 the changes wrought in the human body through the medium 

 of the lungs may be extremely rapid. Yet, after all, further 

 experiments made in London with vaccine virus generated 

 in the country must finally throw a light on what now 

 certainly appears obscure and mysterious. 



The principal variation perceptible to me in the action 

 of the vaccine virus generated in London from that pro- 

 duced in the country was its proving more certainly in- 

 fectious and giving a less disposition in the arm to inflame. 

 There appears also a greater elevation of the pustule above 

 the surrounding skin. In my former cases the pustule 

 produced by the insertion of the virus was more like one 





