Except in asylums, dysentery in this country is a rare disease to-day. Yet it was once far otherwise, and to our ancestors the “bloody flux” was a household word. It was endemic here from the earliest times, and as we follow it down we find that it always presents the same characteristics of bursting out in an epidemic form at fairly regular intervals, then dying down to isolated cases for a longer period until the cycle was complete for the next outbreak. It was only in the latter half of the nineteenth century that it vanished from our midst, and so complete has been its departure that it has also disappeared from our memories, and to-day we have forgotten what a virulent pestilence it once was.