 In the early 20th century the psychical researcher Albert von Schrenck-Notzing investigated the medium Eva Carrière and claimed her ectoplasm "materializations" were not from spirits but the result of "ideoplasty" in which the medium could form images onto ectoplasm from her mind.Schrenck-Notzing published the book "Phenomena of Materialisation" (1923) which included photographs of the ectoplasm.Critics pointed out the photographs of the ectoplasm revealed marks of magazine cut-outs, pins and a piece of string.