My thanks to charles and the two Tims for authoritative apostrophic
information. I will now have to go over my manuscript to delete my
over-correctness. Having been warned,I will avoid the doctors who object
to the abbreviation of "Saint" and the patients who object to the
apostrophe. I take it this information comes from someone intimately
acquainted with the place? -- in whatever role?
        Apostrophes are having a bad time these days.  They
disfigure the plurals of proper names --"the Smith's" and get into
compromising positions in pronouns -- "her's" and "their's." Now I have to
reluctantly accept tradition instead of virtue -- how often we are called
upon to do this!