Professor Lenoir's excellent paper has provided me with a welcome opportunity to revisit, so to speak, a landscape with which I was closely familiar some twenty years ago, and to review it through the eyes of a more recent visitor. The landscape — nineteenth-century German physiology — has not changed of course; but every pair of eyes sees things somewhat differently, and every visitor looks at different things. Even when using an already existing map, the enterprising visitor will enter still uncharted roads and try to see more than appears on the map. Ultimately, he will have traveled the old roads and beyond, bringing back a new, more comprehensive map and a picture drawn from a broader perspective.