Joseph Magrou first studied organ at Conservatoire de Paris with Louis Vierne and then moved to medicine. Under the influence of his cousin, the famous orchidologist Noel Bernard, he specialized in botany and microbiology and becames director of a laboratory at Institut Pasteur and fellow of Académie des Sciences. He was also organist at the church of Hopital militaire du Val de Grâce. The organ there is a Cavaillé-Coll, 1853, with 2 keyboards and 21 stops.