The Dawn of Modern Medicine / An Account of the Revival of the Science and Art of Medicine Which Took Place in Western Europe During the Latter Half of the Eighteenth Century and the First Part of the Nineteenth

by Albert H. Buck

April 10, an efflorescence of the size of a shilling spread around the inferior wound.

April 11, the incision assumed a kind of erysipelatous elevation; the efflorescence much increased.

April 12, still further increase in the efflorescence; a vesicle about the size of a large split pea, and containing a brownish clear fluid, had also formed close to the superior incision; and a still larger one was visible near the edge of the inferior incision. The erysipelas extended to the shoulder and then quickly subsided. The child showed no signs of indisposition the whole time.

In March, 1792, a fresh inoculation was made. A well-marked inflammatory reaction followed.

At a later date Jenner learned that there were well-authenticated instances to prove that when the true cow-pox broke out among cattle at a dairy and was communicated to the milkers, even they had subsequently contracted small-pox. The discovery of this fact perplexed him greatly. Indeed, in the case of most men the discovery would probably have led to the abandonment of all further experimentation. But Jenner did not allow himself to be discouraged. It occurred to him that the virus of the cow-pox itself might have undergone some change whereby its specific virtues were lost; that, in this deteriorated state, it might have been capable of producing only a local disease upon the hand, but no such influence upon the constitution as is requisite to render the individual unsusceptible of contracting small-pox. In other words, he believed it possible that the same cow might one day communicate a genuine and efficacious preventive, and, the next, nothing but a local affection that would exert no beneficial influence whatever on the constitution. This most ingenious and forcible reasoning, supported by analogies drawn from the well-known properties of the virus of small-pox itself, received an ample confirmation from experience, and was the basis on which some of the fundamental rules for the practice of vaccination were founded. It was ascertained that it was only in a certain state of the pustule that virus was afforded capable of imparting to the constitution its protecting power; that matter taken after this period might excite a local disease, but not of such a sort as to render the individual proof against the effects of variolous contagion.

In 1796 Jenner had an opportunity to carry his investigations a step further.

“Hitherto,” says his biographer, “he had only observed the casual disease and investigated its laws; it yet remained to be proved whether it was possible to propagate the affection by artificial inoculation from one human being to another, and thereby, at will, communicate security to all who were liable to small-pox. An opportunity occurred, on the fourteenth of May, 1796, of instituting this experiment. Matter was taken from the hand of Sarah Nelmes who had been infected by her master’s cows, and inserted by two superficial incisions into the arms of James Phipps, a healthy boy eight years old. He went through the disease apparently in a regular and satisfactory manner; but the most agitating part of the trial still remained to be performed. It was needful to ascertain whether he was secure from the contagion of small-pox. This point, so full of anxiety to Dr. Jenner, was fairly put to issue on the first of the following July. Variolous matter, immediately taken from a pustule, was carefully inserted by several incisions, but no disease followed.”

Shortly afterward Jenner wrote to his friend Gardner:—

You will be gratified in hearing that I have at length accomplished what I have been so long waiting for, viz., the passing of the vaccine virus (the virus of cow-pox) from one human being to another by the ordinary mode of inoculation.... I was astonished at the close resemblance of the pustules, in some of their stages, to the variolous pustules. But now listen to the most delightful part of my story. The boy has since been inoculated for the small-pox, which, as I ventured to predict, produced no effect. I shall now pursue my experiments with redoubled ardor.

My readers can easily imagine with what deep anxiety mingled with an intense desire for a completely successful result, Jenner, from this time forward, prosecuted his labors. Unfortunately, he was not able, owing to the disappearance of cow-pox from the dairies of the region in which he lived, to resume his experimental work before the spring of 1798. He was also not willing to make a public announcement of the important results which he had obtained until he should have amply confirmed their accuracy by further experimentation. It was therefore not until during the early part of the summer of 1798 that he issued a printed pamphlet of a little more than seventy pages, in the quarto form, and bearing the title “An Inquiry into the Causes and Effects of the Variolae Vaccinae.”