There has been but one other period in the history of medicine when so many systems of the healing art were in vogue. In the seventeenth century, during the Reform Period, following the many epoch-making discoveries, as the blood and lymph circulation; when alchemy was abandoned and chemistry became a science; when Galileo regenerated physics, and zoology and botany were largely extended; when Newton enunciated the laws of gravitation; when cinchona bark, the great febrifuge, was introduced into Europe, and the cell doctrine was founded by Hooke, Malpighi and Grew, the old Hippocratic, Galenic and Arabic systems of medicine were undermined. In that transition period, when the medical profession was trying to adjust its practice with the many new theories, its authoritative voice was lost, and in the struggle for something tangible, innumerable new systems sprang up.