It is a remarkable fact, and well-known to many, that we are frequently foiled in our endeavours to communicate Smallpox by inoculation to blacksmiths, who in the country are farriers. They often, as in the above instance, either resist the contagion entirely, or have the disease anomalously. Shall we not be able now to account for this on a rational principle?
XIV.—James Cole, Farmer.
Was infected with Horsegrease in the same way as Pearce. Some years afterwards was inoculated with Smallpox, but only a few eruptions appeared on his forehead, which passed away without maturation.
XV.—Abraham Riddiford, Farmer.
Was affected with very painful sores in both hands, tumours in each arm-pit, and severe and general indisposition, in consequence of dressing a Mare that had sore heels. He was attended by a surgeon, who recognising a similarity of the sores upon his hands with those of Cowpox, and knowing the effect of Cowpox on the human constitution, assured him that he never need fear Smallpox; but, twenty years afterwards, he caught the disease, which ran its regular course.
From these Cases Jenner drew this conclusion—
Although the absorption of matter from sores on the heels of Horses, secures, or nearly secures, the system from variolous infection, yet it is possible that this cannot be entirely relied upon, until a disease has been generated by morbid matter from the Horse on the nipple of the Cow, and passed through that medium to the human subject.
Which conclusion he repeated thus—
The active quality of the virus from the Horse’s heels is greatly increased after it has acted on the nipples of the Cow; as it rarely happens that the Horse affects his dresser with sores; and as rarely that a milkmaid escapes infection when she milks infected Cows. (P. 45.)