difficult enemy to conquer than typhus, we may confidently hope that before long it will be as rare. Here I would like to say a word or two upon one of the most terrible of all acute infections, the one of which we first learned the control through the work of Jenner. A great deal of literature has been distributed, casting discredit upon the value of vaccination in the prevention of small-pox. I do not see how any one who has gone through epidemics as I have, or who is familiar with the history of the subject, and who has any capacity left for clear judgment, can doubt its value. Some months ago I was twitted by the Editor of the Journal of the Anti-Vaccination League for maintaining a curious silence on the subject. I would like to issue a Mount Carmel-like challenge to any ten unvaccinated priests of Baal. I will take ten selected vaccinated persons, and help in the next severe epidemic, with ten selected unvaccinated persons (if available!). I should choose three members of Parliament, three anti-vaccination doctors, if they could be found, and four anti-vaccination propagandists. And I will make this promise--neither to jeer nor to jibe when they catch the disease, but to look after them as brothers; and for the three or four who are certain to die I will try to arrange the funerals with all the pomp and ceremony of an anti-vaccination demonstration. A blundering art until thirty or forty years ago, preventative medicine was made a science by the discovery of the causes of many of the serious epidemic diseases. To any one of you who wishes to know this side of science, what it is, what it has done, what it may do, let me commend Radot's _Life of Pasteur_, which reads like a fairy tale. It is more particularly in connection with the great plagues of the world that man's redemption of man may be in the future effected; I say in the future because we have only touched the fringe of the subject. How little do we appreciate what even a generation has done. The man is only just dead, Robert Koch, who gave to his fellow-men the control of cholera. Read the history of yellow fever in Havana and in Brazil if you wish to get an idea of the powers of experimental medicine; there is nothing to match it in the history of human achievement. Before our eyes to-day the most striking experiment ever made in sanitation is in progress. The digging of the Panama Canal was acknowledged to be a question of the health of the workers. For four centuries the Isthmus had been a white man's grave, and during the French control of the Canal the mortality once reached the appalling figure of 170 per thousand. Even under the most favourable circumstances it was extraordinarily high. Month by month I get the _Reports_ which form by far the most interesting sanitary reading of the present day. Of more than 54,000 employés (about 13,000 of whom are white), the death rate per thousand for the month of March was 8.91, a lower percentage, I