Metapsychics is, according to the physiologist Charles Richet, the scientific study of so-called “paranormal” phenomena. Richet was also interested in the materializations of a mysterious substance that certain mediums are said to produce: “ectoplasm.” In order to conduct independent scientific research, he took part in the founding in 1919 of the Institut métapsychique international (IMI), whose existence was challenged by controversies with the scientific teams of the Sorbonne. One of these disputes concerned the medium Marthe Béraud (1886–1968), known as Eva Carrière. Marthe Béraud took part for around twenty years in experiments supervised by the sculptor Juliette Alexandre-Bisson and, from 1909 onward, by the German physician Albert von Schrenck-Notzing. She was never caught in the act of deception. Numerous anonymous photographs were taken during Eva Carrière’s séances in the presence of von Schrenck-Notzing.