Mark! Here was a third definition of Spurious Cowpox by Jenner.
First, in the Inquiry of 1798, he described Spurious Cowpox as eruptions on the cow underived from horsegrease, producing no erysipelas when inoculated on the human subject, and without effect against Smallpox. True Cowpox was generated from horsegrease, and from horsegrease only.
Second, in the Origin of the Vaccine Inoculation of 1801 all reference to horsegrease was dropped for commercial reasons, whilst the existence of Spurious Cowpox was reasserted “as some varieties of spontaneous eruptions upon the cow.”
Third, before the Physicians in 1807, he removed the spurious disease from the cow altogether, saying, nothing more was meant by Spurious Cowpox than variations in the form and progress of vaccine pustules on the arms of the vaccinated!
In short, to vary the phrase of Betsy Prig, “There never was no Spurious Cowpox.” Slippery, very slippery, was the immortal Jenner.
With the report of the Royal College of Physicians were delivered reports from the London College of Surgeons, and from the Edinburgh and Dublin Colleges of Physicians and of Surgeons.
The report from the London College of Surgeons was considered most unsatisfactory, and could its tenor have been foreseen, the Jennerians might never have asked for it. 1100 circulars were dispatched on 15th December, 1806, to all the members of the College whose addresses were known in the United Kingdom, submitting the following questions—
1st. How many persons have you vaccinated?
2nd. Have any of your patients had Smallpox after Vaccination?