I read recently in the paper that approximately 1,000 frogs rained from the sky on a city in France. Is this actually possible? Do I need to take cover next time I see a dark cloud overhead? Help, I don’t want to croak! –Joe Athey, Annandale, Virginia

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You might think waterspouts or their inland cousins, whirlwinds, would be the source of the expression “raining cats and dogs.” But as usual there are about 50 competing explanations. A sample: (1) It comes from the Greek catadupe, meaning waterfall. In other words, it’s coming down in cataracts. (2) It comes from the Latin cata doxas, “contrary to experience,” i.e., it’s raining unusually hard. (3) In Germanic mythology cats were associated with storms and rain and dogs were symbols of the winds and attendants of Odin, the storm god. Ergo, “raining cats and dogs” meant you had a lot of wind (the dogs’ department) and rain (the cats’). (4) In medieval London storm water would sluice down the narrow streets and drown stray cats and dogs, whose corpses would be discovered in the gutters afterward by emerging humans. Aha! they said, it must have rained C&D.

I enjoy your column but this time I’m afraid you’ve missed. White spots on the fingernails [September 28] are often a sign of zinc deficiency. One source of documentation is Dr. Pfeiffer’s Total Nutrition by Carl C. Pfeiffer, PhD, MD, former director of the Princeton Brain Bio Center (now deceased). He writes, “Remember that one of the easily recognized signs of a zinc deficiency is the appearance of white spots on the fingernails.”