One of the most striking developments of recent years, a development which may be seen in most countries of the civilised world, is that of the recognition of the necessity for preventive measures against disease. This necessity is not only felt in medical and scientific circles, but is, in many instances, quite as keenly appreciated by members of the general public. Few people are now indifferent to an outbreak of a serious infectious disease even in a distant land; and, in case of an outbreak in our own land, we no longer patiently watch it run its course far and wide without making strenuous efforts to check it, but by investigation we try to ascertain its cause, and by segregation and fumigation we keep it somewhat under control. The report of the spread of the “plague” in Eastern Asia at once led to an inquiry as to our preparedness to prevent its being introduced into this country, and to combat it if it gained an entrance. We have now an army of inspectors whose duty it is to watch our food-stuffs, and the way they are handled, to investigate the conditions under which our working classes are asked to labour, to inquire into the surroundings in which the people live, and to prevent pollution of the air and water. We have a service in many parts of the country to instruct mothers how to feed and attend to their children, and the children, when they go to school, are examined to discover whether they are suffering from any disability which would hinder their making use of their opportunities, or which, if not corrected, would tend to become aggravated.