JOHN MARCA, an eminent Italian physician, was born at Rome in 1654. From his earliest years he had a turn to natural history; and studied botany, chemistry, anatomy, and medicine, with great vigour. In 1688 Pope Innocent XI. appointed him his physician and private chamberlain, notwithstanding his youth; and Cardinal Altieri Camerlinga made him his vicar for the installation of doctors in physic, which Pope Clement XI. gave him as long as he lived, as well as continued to him the appointments conferred on him by his predecessor. He died in 1710, after giving his fine library of more than 20,000 volumes to the hospital of the Holy Ghost for the use of the public. This noble benefaction was opened in 1716, in the presence of the pope and most of the cardinals. He wrote many works which are esteemed, the principal of which were collected together, and printed at Geneva in 1718, in two volumes quarto.