APPENDIX G : JENNER 427 



Pox or the Small Pox. Several months afterwards he was again 

 inoculated with variolous matter, but no sensible effect was pro- 

 duced on the constitution. . . . 



I shall now conclude from this Inquiry with some general observa- 

 tions on the subject, and on some others which are interwoven 

 with it. 



Although I presume it may be unnecessary to produce further 

 testimony in support of my assertion " that the Cow Pox protects the 

 human constitution from the infection of the Small Pox," yet it affords 

 me considerable satisfaction to say, that Lord Somerville, the Presi- 

 dent of the Board of Agriculture, to whom this paper was shown by 

 Sir Joseph Banks, has found upon inquiry that the statements were 

 confirmed by the concurring testimony of Mr. Dollan, a surgeon, 

 who resides in a dairy country remote from this, in which these ob- 

 servations were made. With respect to the opinion adduced "that 

 the source of the infection is a peculiar morbid matter arising in the 

 horse," although I have not been able to prove it from actual experi- 

 ments conducted immediately under my own eye, yet the evidence 

 I have adduced appears sufficient to establish it. 



They who are not in the habit of conducting experiments may not 

 be aware of the coincidence of circumstance necessary for their being 

 managed so as to prove perfectly decisive ; nor how often men engaged 

 in professional pursuits are liable to interruptions which disappoint 

 them almost at the instant of their being accomplished. However, 

 I feel no room for hesitation respecting the common origin of the 

 disease, being well convinced that it never appears among the cows 

 (except it can be traced to a cow introduced among the general herd 

 which has been previously infected, or to an infected servant) unless 

 they have been milked by some one who, at the same time, has the 

 care of a horse affected with diseased heels. 



The spring of the year 1797, which I intended particularly to have 

 devoted to the completion of this investigation, proved from its dry- 

 ness, remarkably adverse to my wishes ; for it frequently happens, 

 while the farmers' horses are exposed to the cold rains which fall at 

 that season that their heels become diseased, and no Cow Pox then 

 appeared in the neighborhood. 



The active quality of the virus from the horses' heels is greatly 



