It was a perfectly conventional tour, once around the Milky Way with stops at several of the major stars. It was supposed to take about eighty-eight million years so they planned to be back for supper. In the beginning the students had remained in a fairly close knot around mundo Karftahiti, their instructor, but as the tour progressed some of the more venturesome strayed further and further from the rest of the class. Dro Orena and Dro Xeluchli had wandered a greater distance than usual from th