The parts of biology which we may make thoroughly our own are very few. It may be profitable, therefore, occasionally to take a general survey of the field to see what its sphere of influence may be, what phases of life are being advanced by its discoveries or by the distribution of knowledge which follows. It has seemed to me therefore that it would be appropriate this evening to attempt some such survey of biology, even though it be fragmentary and inadequate. For convenience in arrangement we may group this survey along the lines of practical applications of service to mankind, such as occur in medicine, agriculture and kindred industries, domestic and social life, and those which have to do with the acquisition of knowledge and with education. Applications of biology in medical science, in agriculture and in domestic life have in many cases assumed such intimate and essential character that we often look upon them as applied sciences more than in any other way. While biology has been the foundation of all rational systems of medicine and the constant servant of this most beneficent of human professions, the forms of its uses and the wide reach of its service have so increased in recent years that we almost have excuse in feeling that it is a modern acquisition. Could the ancient disciples of Esculapius, with their views of physiology and anatomy, have seen the present scope of these subjects and the marvelous results in cure and control of diseases by the discoveries and applications in bacteriology, I doubt if they would have recognized it as any part of their biology. Still harder would it have been to appreciate the relations of malarial parasite, mosquito and man whereby a serious disease in the latter is occasioned. Intimate relations of two kinds of life, as evidenced in the common parasites, must have been familiar from early times and their effects duly recognized, though their means of access and necessary life cycles were long misunderstood. But such relations as are found to exist in the production of malaria, Texas fever and yellow fever have been so recently discovered that we count them among the triumphs of our modern science. Indeed the discovery of such a relationship may be considered as having been impossible until the methods of modern research and the basis of knowledge as to life conditions were acquired, and which made it possible to put the disjointed fragments together. With the fragments thus related the riddle seems so simple that we wonder it was not solved before, but we must remember that it is knowledge which makes knowledge possible. These direct advantages in medical science are however but part of the great gift to modern methods of disease control, for the possibilities in the control of disease by sanitation, quarantine, vaccination, etc., and other methods are all based on biological data.