Santiago Ramón y Cajal Image | April 15, 2009May 29, 2018 | Paul Greer Drawing of Purkinje cells (A) and granule cells (B) from pigeon cerebellum by Santiago Ramón y Cajal, 1899. Instituto Santiago Ramón y Cajal, Madrid, Spain From “Structure of the Mammalian Retina” Madrid, 1900 via