“The word ‘ectoplasm’ was not known to the Victorians, and after it was coined by the French spiritualist Charles Richet it vied in favour with ‘teleplasm’ and ‘ideoplasm’. Richet had thought up the term after a seance in 1903.

“There are many descriptions in spiritualist literature of a misty vapour issuing from a medium which sometimes solidifies. When the medium Slade was in Australia in 1878 he produced a cloud-like whitish-grey vapour, ‘Dr’ Monck produced a white patch that turned into a cloudy pillar, and D D Home managed to extrude a variety of clouds that formed into hands. In 1885, Eglinton managed a dingy white-looking substance that swayed and throbbed. Madame d’Esperance, an almost forgotten medium born in 1849 and noted for her looks rather than her phenomena, described the production of ectoplasm as though fine threads were being drawn out of the pores of her skin and woven about her face and hands like a spider’s web. The ‘red, sticky matter’ described by Bournemouth medium, Vincent Turvey, was an unusual variation on the theme, and when Florence Cook was manifesting Katie King the latter ‘was connected with the medium by cloudy, faintly luminous threads’.

“Ectoplasm is supposed to have exuded from any or all of the medium’s orifices, and to have been responsive to light, when it would retract. ‘Ectoplasm’ was captured by an investigator early in this [i.e., the twentieth] century; it burned to an ash, leaving a smell as of horn. Chemical analysis revealed the presence of salt and phosphate of calcium. It is perhaps unfortunate that modern chemists have not had the opportunity to try their skills on this mysterious substance.”

Ronald Pearsall, The Table-Rappers (1972)

Sometimes, ectoplasm could appear inexplicably like a piece of net curtain, as in this 1948 photograph of the Middlesbrough medium Minnie Harrison: