While only a relatively small percentage of us ever have the bad luck to be attacked by typhoid fever, rheumatism, or appendicitis, to say nothing of cholera and smallpox, the vast majority of us have gone through two or more of these diseases of childhood; so that, though the death-rate of each and all of them is low, yet the number of cases is so enormous that the absolute total mounts high. But the pity and, at the same time, the practical importance of this heavy death-roll is that _at least two-thirds of it is absolutely preventable_, and by the exercise of only a very moderate amount of intelligence and vigilance. It is, of course, obvious that in a group of diseases which numbers its victims literally by the million every year there will inevitably occur a certain minute percentage of fatal results due to what might be termed unavoidable causes, like a badly nourished condition of the child attacked, unusual circumstances preventing proper shelter or nursing, or an exceptional virulence of the disease, such as will occur in two or three cases of every thousand in even the most trifling infectious malady. But even after making liberal allowance for what might be termed the unavoidable fatalities, at least two-thirds, and more probably nine-tenths, of the deaths from children's diseases might be prevented upon two grounds:-- First, that they are contagious and absolutely dependent upon a living germ, whose spread can be prevented; and secondly, and practically even more important, that more than half the deaths from them are due, not to the disease itself, but to complications occurring during the period of recovery, caused, for the most part, by gross carelessness on the part of the mother or nurse. A large majority, for instance, of the nearly thirteen thousand deaths attributed to measles are due to bronchitis, caught by letting the child go out-of-doors too soon after recovery, which means, of course, either a chill falling upon the irritated and weakened bronchial mucous membrane, or an infection by one of the score of disease-germs, such as those of influenza, pneumonia, bronchitis, and even tuberculosis, which are continually lying in wait for just such an emergency as this--just such a weakening of the vital resistance. It is a sadly familiar statement in the history of fatal cases of tuberculosis that the trouble "began with an attack of measles," or whooping-cough, or a bad cold, and was mistaken for a mere "hanging on" of one of these milder maladies until it had gained a foothold that there was no dislodging. As breakers of the wall of the hollow square of the body-cells, drawn up to resist the cavalry charges of tuberculosis, pneumonia, and rheumatism, few can be compared in deadliness with the diseases of childhood and "common colds."