the gale be sufficiently furious and the billows sufficiently huge. As it is necessary to admit that even one attack of smallpox does not confer absolute immunity against a second, seeing that some men have had two and even more of such attacks in a lifetime, equally must it be admitted that vaccinated persons, and even many times revaccinated persons, have had attacks of smallpox. In ordinary seasons when smallpox is not prevalent a larger protection is conferred by vaccination than that conferred by the lightning-rod upon the dweller beneath the roof above which it rises. But in seasons of epidemic influence, even though the epidemic be as mild as that which furnishes the theme of this paper, such an influence is appreciable and in many cases highly effective. At these times those who previously were incapable of being vaccinated (even the vaccini culturists occasionally find heifers which cannot be made to serve as vaccinifers) are inoculated with ease; at such times also vaccination can be made effective even after the onset of unmistakable symptoms of smallpox; at such times also even those who have had smallpox can be vaccinated, and that after the recent establishment of convalescence. The ardent advocates of the position that the mild epidemic through which this country has just passed was not one of smallpox pointed with what seemed to them convincing force to the fact that they had successfully vaccinated the victims of the disease immediately after recovery. But the argument was without force. The skin of a person convalescent from smallpox is in an exceedingly irritable state and readily is excited to the production of local symptoms at the point where the needle of the vaccinator has been at play. It has to be borne in mind that the actual introduction of a disease by inoculation is a far more rigid test than mere exposure to a volatile poison, the kind of exposure through which, as a rule, smallpox is acquired. What physician, for example, would dare to inoculate a patient with the virus of smallpox after the most classically perfect vaccination? He would be held criminally liable for the result if, as might happen, in this way he should disseminate the disease throughout the community in which he lived.
But the spurious results cited of vaccination of convalescents from modified smallpox prove nothing. Even highly typical results would not disprove the fact of a previous attack of modified or unmodified smallpox. It has been shown that both the vaccination process and the variolous process may pursue their career at one and the same time in the same body. But Dr. Mosely, of Kentucky, put the question to a decisive test last year when he vaccinated three negroes, each convalescent from smallpox, immediately on his release from quarantine. Each subsequently exhibited classical results of successful vaccination in due time and course.
Respecting the enormous value of vaccination to the human race, it
