It is a most singular thing that a problem which was certainly as abstruse and unusual as any which I have faced in my long professional career should have come to me after my retirement, and be brought, as it were, to my very door. It occurred after my withdrawal to my little Sussex home, when I had given myself up entirely to that soothing life of Nature for which I had so often yearned during the long years spent amid the gloom of London. At this period of my life the good Watson had passed almost beyond my ken. An occasional week-end visit was the most that I ever saw of him. Thus I must act as my own chronicler. Ah! had he but been with me, how much he might have made of so wonderful a happening and of my eventual triumph against every difficulty! As it is, however, I must needs tell