which make the outer air pass through an antidote. They must be as easily accessible as a subway—even more accessible. This virtually involves rebuilding modern cities, if the inhabitants expect to survive a war. It is absurd, of course.
Unless some General Staff in Europe is hugging a deep and sinister secret, we have not yet found the killing ray. That lies beyond the present frontiers of science; its discovery involves pioneer work. If it comes, it may change and intensify warfare in many ways which we cannot at present conceive. But warfare by disease-bearing bacilli is already preparing in the laboratories. Here, for example, is one method which I have heard suggested and which, I learn from men of science, seems quite possible: Find some rather rare disease, preferably one which flourishes in a far corner of the world, so that people of your own region have no natural immunity against it, just as the American Indians have no immunity against measles. Experiment until you find a good, practical serum which may be manufactured on a wholesale scale. Cultivate the bacilli until they are strengthened to that malignant stage with which the recent influenza epidemic made us familiar—that can be done with some species of bacilli. Innoculate your own army; if necessary your own civilian population. Then by night-flying aeroplanes, by spies, by infected insects, vermin or water, by any other means which ingenuity may suggest, scatter the germs among the enemy forces. In a
