disease," even though the infant nursed the mother throughout the illness.
Experience has abundantly proved that, when babies not vaccinated, are so exposed, the result has invariably been directly the opposite. In fact, the evidence in this matter is so abundant and of so conclusive a character that all who have taken the trouble to observe or study it during the past five years must be convinced that perfectly vaccinated persons are absolutely protected from small-pox, at least to the same extent as if they had already experienced the disease.
Why, then, it may be asked, do vaccinated persons have the disease at all? Simply because, in order to have the protection perfect, the vaccination must be perfect; and to this end two things are absolutely necessary: 1. The primary vaccine vesicle must be of proper size and character, and must run its proper and normal course. 2. Revaccination must be performed at proper intervals, namely, within five years after the primary, and again soon after puberty in those who are vaccinated in infancy, and at least one revaccination in those whose first vaccination was after maturity.
It is here that the great fallacy of statistics upon this subject is found; and this is why the English statistics before quoted show that, out of 22,000 cases of small-pox treated in the hospitals, 17,000 had been vaccinated. They had been vaccinated in infancy—perhaps properly, perhaps improperly—but in all probability had never been revaccinated. It should be once for all understood that, in order to have full protection, revaccination at the proper periods is just as necessary as the original vaccination.
It should be understood that a primary vaccination is not expected to protect for a long series of years, but only for a few years; and that after a limited time, although it may modify more or less the severity of the disease, it ceases to be absolutely protective, and must be renewed.
Statistics, however, show that, of persons attacked with small-pox, from three to four times as many deaths occur among those who have not been vaccinated at all as among those who are reckoned as vaccinated, though it may have been only in infancy. They also show that such vaccinations are nearly worthless as protection against smallpox after several years have elapsed, and very uncertain even in their power to modify the disease.
II. Concerning the transmission of other diseases by means of vaccination.
It may be presumed that if bad results of any kind were to follow vaccination, it would happen in primary cases, where the virus exerts its full influence of every kind. It has been seen with what care all these primary vaccinations have been watched during the past few years, the oversight extending even beyond the perfect healing of the arm. A circular was left in each family, requesting that any unfavor-
