THIS is the fourth time the British Association for the Advancement of Science has met in Canada-first in 1884 in Montreal, in this city in 1897, and in Winnipeg in 1909. The addresses given on these occasions dealt with the advancement of knowledge in archaeology and physics. It is now my privilege, as a member of the medical profession, to address you on the advances made during the same period in our knowledge of disease and our means of coping with and preventing it.