stoutfellow

True enough, most of my comment rests on things learned since The Caves of Steel was written. (I think the problem of bacterial mutation may have been recognized by then, though.) I wonder, though. I know that Asimov, years later, wrote a number of other books involving Daneel Olivaw, but I haven't read any of them except The Robots of Dawn. Do you know whether he did any retconning on these points (as he did with various questions involving Trantor in Foundation's Edge)?