188 EDWARD JENNER 



in such a way as to infect him. What confusion should we 

 have were there no other mode of inoculating the smallpox 

 than such as would happen from handling the diseased skin 

 of a person labouring under that distemper in some of its 

 advanced and loathsome stages! It must be observed that 

 every case of cow-pox in the human species, whether com- 

 municated by design or otherwise, is to be considered as a 

 case of inoculation. And here I may be allowed to make 

 an observation on the case of the farmer communicated to 

 me by Dr. Ingenhousz. That he was exposed to the matter 

 when it had undergone the putrefactive change is highly 

 probable from the doctor's observing that the sick cows at 

 the farm gave out an offensive stench from their udders. 

 However, I must remark that it is unusual for cattle to 

 suffer to such an extent, when disordered with the cow- 

 pox, as to make a bystander sensible of any ill smell. I 

 have often stood among a herd which had the distemper 

 without being conscious of its presence from any particular 

 effluvia. Indeed, in this neighbourhood it commonly re- 

 ceives an early check from escharotic applications of the 

 cow leech. It has been conceived to be contagious with- 

 out contact; but this idea cannot be well founded because 

 the cattle in one meadow do not infect those in another 

 (although there may be no other partition than a hedge) 

 unless they be handled or milked by those who bring the 

 infectious matter with them; and of course, the smallest 

 particle imaginable, when applied to a part susceptible of 

 its influence, may produce the effect. Among the human 

 species it appears to be very clear that the disease is pro- 

 duced by contact only. All my attempts, at least, to com- 

 municate it by effluvia have hitherto proved ineffectual. 



As well as the perfect change from that state in which 

 variolous matter is capable of producing full and decisive 

 effects on the constitution, to that wherein its specific prop- 

 erties are entirely lost, it may reasonably be supposed that 

 it is capable of undergoing a variety of intermediate 

 changes. The following singular occurrences in ten cases 

 of inoculation, obligingly communicated to me by Mr. Trye, 

 Senior Surgeon to the Infirmary at Glocester, seem to indi- 

 cate that the variolous matter, previously to its being taken 





