VACCINATION AGAINST SMALLPOX 217 



ter the same disease under a peculiar, and at present an 

 inexplicable, modification. 



One experiment tending to elucidate the point under 

 discussion I had myself an opportunity of instituting. On 

 the supposition of its being possible that the cow which 

 ranges over the fertile meadows in the vale of Gloucester 

 might generate a virus differing in some respects in its 

 qualities from that produced by the animal artificially pam- 

 pered for the production of milk for the metropolis, I pro- 

 cured, during my residence there in the spring, some cow 

 pock virus from a cow at one of the London milk-farms. 1 

 It was immediately conveyed into Gloucestershire to Dr. 

 Marshall, who was then extensively engaged in the inocu- 

 lation of the cow-pox, the general result of which, and 

 of the inoculation in particular with this matter, I shall 

 lay before my reader in the following communication from 

 the doctor: 



"DEAR SIR: 



" My neighbour, Mr. Hicks, having mentioned your wish 

 to be informed of the progress of the inoculation here for 

 the cow-pox, and he also having taken the trouble to 

 transmit to you my minutes of the cases which have fallen 

 under my care, I hope you will pardon the further trouble 

 I now give you in stating the observations I have made upon 

 the subject. When first informed of it, having two chil- 

 dren who had not had the smallpox, I determined to inocu- 

 late them for the cow-pox whenever I should be so fortunate 

 as to procure matter proper for the purpose. I was, there- 

 fore, particularly happy when I was informed that I could 

 procure matter from some of those whom you had in- 

 oculated. In the first instance I had no intention of extend- 

 ing the disease further than my own family, but the very 

 extensive influence which the conviction of its efficacy in 

 resisting the smallpox has had upon the minds of the 

 people in general has rendered that intention nugatory, as 



tions. In this opinion Dr. Woodville has concurred The axiom of the im- 

 mortal Hauter, that two diseased actions cannot take Place at the same time 

 in one and the same part, will not be injured by the admission of this theory. 

 It was taken by Mr. Tanner, then a student at the Veterinary College, 

 from a cow at Mr. Clark's farm at Kentish Town. 



