EDWARD JENNER 153 



consideration of the change which the infectious matter undergoes 

 from producing a disease on the cow, may we not conceive that many 

 contagious diseases, now prevalent among us, may owe their pres- 

 ent appearance not to a simple, but to a compound origin? For ex- 

 ample, is it difficult to imagine that the measles, scarlet fever, and 

 the ulcerous sore throat with a spotted skin, have all sprung from 

 the same source, assuming some variety in their forms according to 

 the nature of their new combinations ? The same question will apply 

 respecting the origin of many other contagious diseases, which bear 

 a strong analogy to each other. 



There are certainly more forms than one, without considering the 

 common variation between the confluent and distinct, in which the 

 Small-pox appears in what is called the natural way. About seven 

 years ago a species of Small-pox spread through many of the towns 

 and villages of this part of Gloucestershire : it was of so mild a nature 

 that a fatal instance was scarcely ever heard of, and consequently so 

 little dreaded by the lower orders of the community that they scrupled 

 not to hold the same intercourse with each other as if no infectious 

 disease had been present among them. I never saw nor heard of an 

 instance of its being confluent. The most accurate manner, perhaps, 

 in which I can convey an idea of it, is, by saying that had fifty in- 

 dividuals been taken promiscuously and infected by exposure to this 

 contagion, they would have had as mild and light a disease as if they 

 had been inoculated with variolous matter in the usual way. The 

 harmless manner in which it showed itself could not arise from any 

 peculiarity either in the season or the weather, for I watched its prog- 

 ress upwards of a year without perceiving any variation in its general 

 appearance. I consider it then as a variety of the Small-pox. 



[In some of the preceding cases I have noticed the attention that 

 was paid to the state of the variolous matter previous to the experi- 

 ment of inserting it into the arms of those who had gone through the 

 Cow-pox. This I conceived to be of great importance in conducting 

 these experiments, and were it always properly attended to by those 

 who inoculate for the Small-pox, it might prevent much subsequent 

 mischief and confusion. With the view of enforcing so necessary a 

 precaution, I shall take the liberty of digressing so far as to point out 

 some unpleasant facts relative to mismanagement in this particular, 

 which have fallen under my own observation.] 



