Where Jenner had not learned to discriminate, the line became clear in the course of general practice; and Pearson was especially explicit as to the right time for taking virus; but to make good his claim to national consideration, Jenner fancied it necessary to exhibit himself as complete master of the art of Cowpox Inoculation, owing nothing to others; and he therefore proceeded to appropriate the fruit of the common medical experience, assigning it to a season when he alone was in the field. Referring to his separation of true from spurious Cowpox, he thus prosecuted his raid—

This impediment to my progress was not long removed before another, of far greater magnitude in appearance, started up. There were not wanting instances to prove that when the true Cowpox broke out among the cattle at a dairy, the person who had milked an infected animal, and had thereby gone through the disease in common with others, was liable to receive the Smallpox afterwards. This, like the former obstacle, gave a painful check to my fond and aspiring hopes; but reflecting that the operations of Nature are generally uniform, and that it was not probable the human constitution (having undergone the Cowpox) should in some instances be perfectly shielded from the Smallpox, and in many others remain unprotected, I resumed my labours with redoubled ardour. The result was fortunate; for I now discovered that the virus of Cowpox was liable to undergo progressive changes from the same cause precisely as that of Smallpox, and that when it was applied to the human skin in its degenerated state, it would produce the ulcerated effects in as great a degree as when it was not decomposed, and sometimes far greater; but having lost its specific properties, it was incapable of producing that change upon the human frame which is requisite to render it insusceptible of the variolous contagion: so that it became evident a person might milk a Cow one day, and having caught the disease, be for ever secure; while another person, milking the same Cow the next day, might feel the influence of the virus in such a way as to produce a sore, or sores, and, in consequence of this, might experience an indisposition to a considerable extent; yet, as has been observed, the specific quality being lost, the constitution would receive no peculiar impression....

This observation will fully explain the source of those errors which have been committed by many inoculators of the Cowpox. Conceiving the whole process to be extremely simple, as not to admit of a mistake, they have been heedless about the state of the Vaccine Virus; and finding it limpid, as part of it will be, even in an advanced state of the pustule, they have felt an improper confidence, and sometimes mistaken a spurious pustule for that which possesses the perfect character.

No one apparently thought it worth while to expose the fictitious character of these statements, invented by Jenner to justify his pretensions and to baffle objections. Any careful reader of the Inquiry of 1798, and the Origin of Vaccine Inoculation of 1801, cannot fail to perceive the radical inconsistency of the earlier and later narratives, and how a few hasty experiments enveloped in unverifiable conjecture and gossip, came to be magnified into years of arduous research.

He wound up his statement with this flourish and prediction—

The distrust and scepticism which naturally arose in the minds of medical men, on my first announcing so unexpected a discovery, has now nearly disappeared. Many hundreds of them from actual experience, have given their attestations that the inoculated Cowpox proves a perfect security against the Smallpox; and I shall probably be within compass if I say thousands are ready to follow their example; for the scope that this Inoculation has now taken is immense. An hundred thousand persons, upon the smallest computation, have been inoculated in these realms. [May, 1801.] The numbers who have partaken of its benefits throughout Europe and other parts of the globe are incalculable; and it now becomes too manifest to admit of controversy, that the annihilation of the Smallpox, the most dreadful scourge of the human species, must be the final result of this practice.

For the end designed—to establish and exalt a claim with the purpose of exacting corresponding recompense, the Origin of the Vaccine Inoculation was an adroitly drawn document: its veracity is a different matter. A just man, not to say a generous, would have had some praise for Pearson, Woodville, and others to whom the extension of the New Inoculation was due; but Jenner was essentially a mean spirit; and for him to have stated his case truly would have been to jeopardise “the fond hope of enjoying independence.”

FOOTNOTES:

[124] Baron’s Life of Jenner, vol. i., p. 140.

[125] Baron’s Life of Jenner, vol. i., p. 448.