seems someone does not want me to respond as I have lost 3 posts
Many "medical" organisations use a symbol of a short rod entwined by two snakes and topped by a pair of wings, which is actually the caduceus or magic wand of the Greek god Hermes (Roman Mercury), messenger of the gods, inventor of (magical) incantations, conductor of the dead and protector of merchants and thieves. It is derived from the Greek karykeion = "herald's staff", itself based on the word "eruko" meaning restrain, control.
It is interesting to see that most of organisations using this symbol are generally either commercial or military (or American). New Zealand examples include drug and pharmaceutical companies. A study by Friedlander confirms this impression.
The link between the caduceus of Hermes (Mercury) and medicine seems to have arisen by the seventh century A.D., when Hermes had come to be linked with alchemy. Alchemists were referred to as the sons of Hermes, as Hermetists or Hermeticists and as "practitioners of the hermetic arts". There are clear occult associations with the caduceus.
The caduceus was the magic staff of Hermes (Mercury), the god of commerce, eloquence, invention, travel and theft, and so was a symbol of heralds and commerce, not medicine. The words caduity & caducous imply temporality, perishableness and senility, while the medical profession espouses renewal, vitality and health. [link to drblayney.com
I had much more but keep getting censured-baned as it were...