No department of medical science has made greater advances in modern times than that which is termed "Preventive Medicine." Nor is there any in which the public at large is more deeply interested, and the knowledge of which it is of more importance should be diffused as widely as possible. The devoted and zealous service rendered by the medical profession in all questions relating to the maintenance of health and the prevention of disease is a sufficient answer, if any be needed, to the ignorant and prejudiced statements that are sometimes made, that in support of various scientific theories and proceedings medical men are actuated by interested and selfish motives. No name stands, or will ever stand, out more brilliant among the benefactors of mankind than that of Edward Jenner, by whose genius and labours untold multitudes of human lives have been saved, and an incalculable amount of human suffering and misery prevented. At the present time various circumstances, both social and scientific, have combined to recall attention to this illustrious man and his remarkable scientific and beneficial labours. It is not, however, our intention on the present occasion to give either a complete sketch of his life, or a detailed account of his work. But in order to show the connection between his discoveries and more recent advances in the same field of scientific investigation, it will be necessary to give a brief _resume_ of Jenner's life-work, and the benefits which he conferred on the human race throughout the world.