Edward Jenner — "The deviation of the Cow Pox from its true character appears to be very frequent…"
The deviation of the Cow Pox from its true character appears to be very frequent; and when it does appear, it is, as far as I have seen, uniformly in the following manner: The vesicle, instead of being pellucid, and having a circular form, with its edges a little elevated, becomes of an opaque white, and its edges are more depressed than its centre, so that it resembles a small pearl. Sometimes it is surrounded by an erysipelatous inflammation.
