sunlight because these are the great enemies of all kinds of bacteria. We force his feeding and try to stimulate his appetite, hoping thereby to give him strength so that his blood cells will fight actively in his interest. We take steps to reduce his fever so that his strength may not be wasted and burned up. If we succeed, with the necessary active coöperation of the patient, the blood cells finally overcome the bacteria and the patient recovers from the disease. This is the story of the invasion of almost every disease. It is the story of the white blood cell. The white blood cell is active in another way and it is a very interesting way. When you cut yourself the blood cells immediately surround the entire cut. They line up like an army defending a city. They form a perfect wall, millions of them, ready to pounce upon all enemies in the form of bacteria or microbes, that have the temerity to try to creep into the wound unseen. This is the reason that so very few of the hundreds of little surface wounds and scratches which every one gets, ever become infected or go wrong in any way. When a microbe does get inside, under the skin, and becomes active, as they sometimes will, the white blood cell, appreciating that it cannot defeat the enemy, begins to build a wall around him and locks him in. This compels the enemy to limit his activity within the wall, which he does, and so an abscess is formed, which bursts when the bacteria fill it so full that the wall gives way and empties the poison out on the surface of the skin, thus saving the body from the poison of the microbe which would spread all through the body, were it not for the wall formed by the active, busy little white blood cell. The foregoing simple explanation of "how we catch disease" will no doubt be suggestive to the interested and careful reader. The first and most obvious question that suggests itself is: If we "catch" tuberculosis by inhaling germs from some other person's dried spittle, why are consumptives allowed to spit where it will do harm? Consumptives are not allowed to spit where it will do harm, but they do and they always will. Every department of health in every civilized corner of the globe has secured the enactment of laws making spitting unlawful in any public place. Every sanitary society, every agency whose aim is to work in the interest of public health, has actively aided, and is aiding, in the propaganda for a better universal understanding of the principles of sanitation and hygiene. The individual must be educated to understand the tragic need of such a law. You cannot legislate virtue into the public conscience. It is a profound reflection upon human intelligence to appreciate that the great white plague, for the stamping out of which so many thousands of lives are annually sacrificed, and so much money is spent, could be forever stamped out, if the human race would agree absolutely to stop spitting.