There are some authentic (i.e. not mocked up especially for the occasion) photos purporting to show ectoplasm in this movie. However, though they were seized upon as authentic at the time; most people now acknowledge that what is shown is regurgitated cheesecloth. (Mary Roach's "Spook")
The "One bright day in the middle of the night" poem comes from a tradition in British and Scottish Folklore and has no real author as such. It's considered more as a moral exercise (a "Lying Song") in the tradition of the Miracle Plays than as true nonsense verse.