Nor was the doctor in much happier plight. Even when the life at stake was not one of his own loved ones,--though from the deadly contagiousness of the disease it sadly often was (I have known more doctors made childless by diphtheria than by any other disease except tuberculosis),--he faced his cases by the hundred instead of by twos and threes. The feeling of helplessness, the sense of foreboding, with which we faced every case was something appalling. Few of us who have been in practice twenty years or more, or even fifteen, will ever forget the shock of dismay which ran through us whenever a case to which we had been summoned revealed itself to be diphtheria. Of course, there was a fighting chance, and we made the most of it; for in the milder epidemics only ten to twenty per cent of the patients died, and even in the severest a third of them recovered. But what "turned our liver to water"--as the graphic Oriental phrase has it--was the knowledge which, like Banquo's ghost, would not down, that while many cases would recover of themselves, and in many border-line ones our skill would turn the balance in favor of recovery, yet if the disease happened to take a certain sadly familiar, virulent form we could do little more to stay its fatal course than we could to stop an avalanche, and we never knew when a particular epidemic or a particular case would take that turn. "Black" diphtheria was as deadly as the Black Death of the Middle Ages. The disease which caused all this terror and havoc is of singular character and history. It is not a modern invention or development, as is sometimes believed, for descriptions are on record of so-called "Egyptian ulcer of the throat" in the earliest centuries of our era; and it would appear to have been recognized by both Hippocrates and Galen. Epidemics of it also occurred in the Middle Ages; and, coming to more recent times, one of the many enemies which the Pilgrim Fathers had to fight was a series of epidemics of this "black sore throat," of particularly malignant character, in the seventeenth century. Nevertheless, it does not seem to have become sufficiently common to be distinctly recognized until it was named as a definite disease, and given the title which it now bears, by the celebrated French physician, Bretonneau, about eighty years ago. Since then it has become either more widely recognized or steadily more prevalent, and it is the general opinion of pathologists that the disease, up to some thirty or forty years ago, was steadily increasing, both in frequency and in severity. So that we have not to deal with a disease which, like the other so-called diseases of childhood, has gradually become milder and milder by a sort of racial vaccination, with survival of the less susceptible, but one which is still full of virulence and of possibilities of future danger.