VACCINATION AGAINST SMALLPOX 181 



a single case which I think can be called an exception to 

 the fact I was so firmly impressed with that the cow-pox 

 protects the human body from the smallpox. I have myself 

 received some further confirmations, which shall be subjoined. 

 I have lately also been favoured with a letter from a gentle- 

 man of great respectability (Dr. Ingenhousz), informing me 

 that, on making an inquiry into the subject in the county of 

 Wilts, he discovered that a farmer near Calne had been in- 

 fected with the smallpox after having had the cow-pox, and 

 that the disease in each instance was so strongly characterized 

 as to render the facts incontrovertible. The cow-pox, it 

 seems, from the doctor's information, was communicated to 

 the farmer from his cows at the time that they gave out an 

 offensive stench from their udders. 



Some other instances have likewise been represented to 

 me of the appearance of the disease, apparently marked with 

 its characteristic symptoms, and yet that the patients have 

 afterwards had the smallpox. On these cases I shall, for 

 the present, suspend any particular remarks, but hope that 

 the general observations I have to offer in the sequel will 

 prove of sufficient weight to render the idea of their ever 

 having had existence, but as cases of spurious cow-pox, 

 extremely doubtful. 



Ere I proceed let me be permitted to observe that truth, 

 in this and every other physiological inquiry that has occu- 

 pied my attention, has ever been the object of my pursuit, 

 and should it appear in the present instance that I have been 

 led into error, fond as I may appear of the offspring of my 

 labours, I had rather see it perish at once than exist and do a 

 public injury. 



I shall proceed to enumerate the sources, or what appear 

 to me as such, of a spurious cow-pox. 



First : That arising from pustules on the nipples or udder of 

 the cow; which pustules contain no specific virus. 



Secondly: From matter (although originally possessing the 

 specific virus) which has suffered a decomposition, either 

 from putrefaction or from any other cause less obvious to 

 the senses. 



Thirdly : From matter taken from an ulcer in an advanced 

 stage, which ulcer arose from a true cow pock. 



