Today, when I gave blood, the petite, Hispanic technician informed me that I was now a member of the Gallon Club. She explained that I had made eight visits to the blood center over the years, and, having given eight pints, was now in the ranks. Opening a white file cabinet, she removed a gaudy gold plastic pin in the shape of a drop of blood. It was emblazoned with a red cross on a white field, and in nearly invisible writing below the insignia, it said GALLON (1) DONOR. I graciously accepted the honor. Now, however, I was curious…