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I. The new ilhsory h u r e consists essentkdly of 'units of direction.'Properties of a black and white twisted cord.The Simple unit of direction.II.The properties of the illusoryjigure as illustrated by Fig. 1.TJbe illusion persists wnder all conditions of exawdnation.Fys. 1 and 2 compared.The peculia?. r81e of the chequer-work bmkground. III. The construction descq-ibed a triple seriesof variants oj the illusory jigure.I V. TJhe construction described of two coloured variants.The properties of the coloured variants.Certain visual properties of red and gremishblue demonstrated by two experiments with each of the cotowred variants.The construction qf tJbe circular fisures described (witlh certain properties of some of these jguree).The Compound unit of direction.Properties of these variants.V. VI. General properties oj tAe circular jgures. VII. A n illusoryjigure examined in relation to a corresponding VIII.The Mcnsterberg or chequer board illusion as related to IX.The imture of the unit OJ' dii.ection illusion.CertaiiL non-alusory jigure.tke ' twisted cord on chequer-work background ' illzwio?t.They athe and positive cliaracters indicccted.
James D. Fraser (Wed,) studied this question.