In the early stages of the development of mankind it was all that each individual could do to supply his own necessities. As he advanced in civilization, he produced more than he himself needed, and thereby had a surplus to exchange with his neighbors for things which he desired. As his productive capacity increased, a larger number of men were enabled to apply themselves to the arts and sciences. The degree of civilization to which a community can reach is in the main governed by the amount of the necessities of life that the labor of one man applied to the land can produce. If one man’s labor can produce enough of the necessities to support himself and one other man, we have a certain degree of civilization and refinement. If his labor produces enough to support himself and two other men, a higher degree of civilization results. In the tropics one man’s labor applied to natural opportunities is able to support more men than the same amount of labor applied in any other part of the world. In the long run, therefore, the great civilizations of the future will be located in the tropics. No doubt the great centers of civilization will remain for centuries much as they are at present. The white settlers will go to the valleys of the Amazon and Congo, building up large agricultural communities which will supply the European and American centers located as they are at present with their food supply. But in the course of ages the centers of civilization will move to where a given amount of labor will produce the largest amount of food. Of course, other things must be equal. I am assuming that the government in these new communities is as good as the government with which we are comparing it in the temperate zone. When this great migration of population has fully commenced, I believe that the peoples of that day will look back upon the sanitary work done at the Canal Zone as the first great demonstration that the white man could live as well in the tropics as in the temperate zone. I am inclined to think that at this time the sanitary phase of the work will be considered more important than the actual construction of the Canal itself, as important to the world as this great waterway now is, and will be for generations to come. The discovery of the Americas was a great epoch in the history of the white man, and threw large areas of fertile and healthy country open to his settlement. The demonstration made at Panama that he can live a healthy life in the tropics will be an equally important milestone in the history of the race, and will throw just as large an area of the earth’s surface open to man’s settlement, and a very much more productive area. INDEX Agramonte, Dr., 11, 16, 41. Albertini, Dr. Antonio, 12. American Medical Association, interest of, in Panama sanitation, 142.