 McCay destroyed many of his original cans of film to create more storage space . Of what film he kept , much has not survived , as it was photographed on original 35mm nitrate film , which deteriorates and becomes inflammable in storage . Mendelsohn 's son and a friend , both young animators , discovered the film in Mendelsohn 's possession in 1947 and rescued what they could . In some cases , such as The Centaurs , only fragments could be saved . A negative and incomplete positive was discovered of Performing Animals , a film of animals playing instruments that may have been intended for McCay 's vaudeville act ; it was deemed unsalvageable and destroyed . 
