An explanatory theory of materialization phenomena that
suggests that the white substance issuing from a mediums
body, which is taken for ectoplasm, is something that the medium
swallowed before the sitting and brought up at the appropriate
moment. The theory was put forward by the Society for
Psychical Research, London, in the case of Eva C., accused of
fraud in 1922. Wide public attention was also aroused by the
case of the British medium Helen Duncan, in which the theory
was considered a satisfactory explanation.
Price, Harry. Regurgitation and the Duncan Mediumship.
Council at the Rooms of the National Laboratory of Psychical
Research, London, 1931.