II.--In the same line of defence, we have the claim made for an extraordinary salvation of human life. Thus Sir Spencer Wells in a recent speech observed, “Jenner is immortal as a benefactor of mankind. It may not be generally known, but it is true, that Jenner has saved, is now saving, and will continue to save in all coming ages, more lives in one generation than were destroyed in all the wars of Napoleon.” The answer to such a statement is to call for proof of the lives saved. There is no proof. At the close of last century, 20 per cent. of the mortality of Glasgow was due to smallpox. Smallpox abated, but did mortality abate? Not in the least. Dr. Robert Watt in 1813 recorded the fact with amazement over it. And what was true of Glasgow was true of other cities and other populations. There may be a cessation of smallpox, but (unless the result of sanitary improvement) the work of death is merely transferred to cognate agencies. There is no saving of life. What was a mystery to Watt is less of a mystery since the development of sanitary science. Zymotic disease in its various forms is a definite evolution from definite insanitary conditions. It is not affected by medical repression, nor by the spontaneous substitution of one variety of fever for another. In the words of Dr. Farr, “To save people from smallpox is not enough whilst exposed to other forms of disease. Thus in a garden where the flowers are neglected, to keep off thistle-down merely leaves the ground open to the world of surrounding weeds.” To lower the zymotic death-rate it is necessary to reduce the conditions in which zymotic disease is generated. Citing Dr. Farr once more, “To operate on mortality, protection against every one of the fatal zymotic diseases is required; otherwise the suppression of one disease-element opens the way for others.” Dr. Watt and Dr. Farr alike believed that vaccination stopped smallpox, and alike realised that the disappearance of smallpox was accompanied with no saving of life. Sir Spencer Wells is of a contrary opinion, which he shares with a number of people who prefer the free, play of the prejudiced imagination to the sobriety of exact information. WHO ARE THE UNVACCINATED? III.--Then we are asked to believe that though vaccination may not keep off smallpox, it makes it milder, and in proof we are entertained with low rates of mortality among the vaccinated and high rates among the unvaccinated. We reply, to make a fair comparison between the vaccinated and the unvaccinated, it would be necessary to compare class with class, physique with physique, age with age. In other words, the subjects of smallpox should be constitutionally equal, their difference being limited to vaccination present or vaccination absent. So much is obvious.