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Titre : A course in experimental psychology. Part 1 / by Edmund C. Sanford,...
Auteur : Sanford, Edmund Clark. Auteur du texte
Éditeur : D. C. Heath (Boston)
Date d'édition : 1897-1898
Sujet : Sens et sensations
Notice d'ensemble : http://catalogue.bnf.fr/ark:/12148/cb372735278
Type : monographie imprimée
Langue : anglais
Format : 2 vol. (IV-183, VIII-p. 184-449) : ill. ; in-8
Format : Nombre total de vues : 280
Description : Collection numérique : Originaux conservés à la Bibliothèque H. Ey (C. H. Sainte-Anne, Paris)
Description : Contient une table des matières
Droits : Consultable en ligne
Droits : Public domain
Identifiant : ark:/12148/bpt6k77076b
Source : Bibliothèque H. Ey. C.H. de Sainte-Anne, 720-98
Conservation numérique : Bibliothèque nationale de France
Date de mise en ligne : 15/10/2007
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115. Thé YeUow Spot, thé 3ï<M~o. LM~a. The projection of the yellow spot in the visual field eau be made visible in several wa.ys. Two have aiready been mentioned in Ex. 111 others are as follows Close thé eyes for a few seconds and then look through a nat-aided bottle of chrome alum solution at a brightiy lighted surface or at thé clear sky. In the blue-green solution a rose-colored spot will be seen which corresponds to the yellow spot. Thé light tliat cornes through the chrome a.lum solution is chiefly a mixture of red and green and blue. The pigment of the yellow spot absorbs a portion of the Mue and green and transmits thé rest, which! makes a, rose-colored mixture, to the visua.1 orga.ns behind it. The sa.me ca.n be very beautifuUy demonstra-ted with violet or purple gélatine slieets. Helmhokz, ~4, Fr. 548-&51 (419-421); M&xwen; Sachs; Henng, C. 116. Intermittent Illumination. Thé region of the yellow spot can be seen, together with many other curious figures and patterns, when the illumination of a single eye is made intermittent by moving thé spread nngers rapidiy to and fro before it. Something may be seen when the open eyes are fixed on a uniformiy lighted surface, but more when they are turned with elosed lidstoward a bright sky or the sun itself. Thé ngures probably differ in différent eyes and some are beautiful and plaborate. Sometimes with steady fixation thé ngures give place more or less completely to a général streaming of hne particles, suggesting thé nying specks of Ex. 112, but nner and of less regular course. Vierordt credited the appearance to thé circulation of thé blood in thé retinal vessels; Helmholtz is inclined to think the fine particles lymph corpuscles rather than blood corpuscles. Similar phenomena are to be observed with black and white disks when rotated at less speed than that required for uniform mixing of tlie black and white.
Helmholtz, .i, 532 f., Fr. 502 (~81) f.; Exner,