Such was the doctrine of the Inquiry, “that master-piece of medical induction.”
When the doctrine came to be reduced to practice, difficulties arose. Cowpox was considered wholesome and credible, whilst horsegrease was repulsive and incredible. Still fact was fact; and many were ready to accept horsegrease through the cow, or without the cow, if such indeed were the source of the new salvation. Cowpox proved to be a rare commodity, whilst horsegrease was common, and numerous attempts were made to produce cowpox by means of grease, but ineffectually. At some attempts, Jenner officiated. Marshall records that—
Mr. Sewell, Assistant Professor at the Royal Veterinary College, informs me that he was a witness to a series of experiments, twice repeated, at the College in the presence of Dr. Jenner, Dr. Woodville, Mr. Wachsel, and Mr. Turner, with a view to produce the vaccine disease on the teats of a cow. The matter of grease had been immediately taken from the horse, and variously applied by long continued friction, punctures, scarifications, and by scratching the surface with a needle; but from these trials neither inflammation, nor any affection resembling a pock resulted.[190]
To this discomfiture Jenner had to submit. His ascription of cowpox to horsegrease was stigmatised as an error of which the less that was said the better. It is true that other experimenters were more successful, and that Loy of Whitby and Sacco of Milan dispensed with the cow as a superfluity and used matter direct from the horse for inoculation, passing the virus from arm to arm into general circulation until what was equine was lost sight of and indistinguishable from what was vaccine; but Jenner did not care to be justified at the risk of his popularity and the money on which he had set his heart. He saw how the wind of public favour was blowing, and went with it. Since horsegrease was disliked, he consented to its oblivion. Pearson, the chief promoter and organiser of vaccination, scoffed at horsegrease, and used spontaneous cowpox, which Jenner knew was of no avail against smallpox; but he entered no protest upon that score. On the contrary, he let the futile practice go on; he claimed it as his own; and he set about manufacturing excuses for the failures which were imminent.
Spurious cowpox was one of the most dexterous of these excuses. If injury or smallpox followed vaccination, the disaster was ascribed to spurious cowpox. Jenner’s Further Observations, published in 1799, was designed to teach “how to distinguish with accuracy between that peculiar pustule which is the true Cow Pock and that which is spurious;” and in his Origin of the Vaccine Inoculation in 1801 even greater stress was laid on the distinction. By and bye, however, the excuse worked more harm than advantage. People got terrified with the mischiefs ascribed to spurious cowpox, and as which was genuine and which spurious was only discoverable in their consequences, they began to decline to have either. It then became expedient to deny spurious cowpox, which Jenner did. He confessed to the Royal College of Physicians that there was not a true and a false cowpox; and that by spurious cowpox he “meant nothing more than to express irregularity in the form and progress of the vaccine pustule from which its efficacy is inferred.”
In view of facts like these, there is little cause for surprise that the publication of Jenner’s Inquiry with its two supplements was not continued. What he set forth as essential was treated as illusory, whilst the cowpox in which he had taught there was no security had been brought into use everywhere. Why therefore embarrass himself with proclamations of his own blunders? The believers in vaccination were good-natured and incurious, and he had their homage, which was agreeable and profitable, and why should he dissipate it? The Inquiry was printed for the third time in 1801, but “this master-piece of medical induction” has never been republished; and the probability is, that if ever reproduced, it will be to prove to the world the emptiness of its author’s pretensions.
Jenner’s original promises of immunity from smallpox by inoculation with horsegrease cowpox were absolute. Thus he wrote—
The person who has been affected with Cowpox Virus is for ever after secure from the infection of the Smallpox.[191]
It clearly appears that this disease, Cowpox, leaves the constitution in a state of perfect security from the infection of the Smallpox.[192]
Cowpox admits of being inoculated on the human frame with the most perfect ease and safety, and is attended with the singularly beneficial effect of rendering through life the person so inoculated perfectly secure from the infection of the Smallpox.[193]