[236] Physiol. Optik, pp. 562-71.
[237] Physiol. Psych., pp. 107-8.
[238] Grundtatsachen des Seelenlebens, pp. 526-30.
[239] Cf. supra, vol. I. p. 515 ff.
[240] See Archiv f. Ophthalm., v. 2, 1 (1859), where many more examples are given.
[241] Untersuchungen, p. 250; see also p. 242.
[242] I pass over certain difficulties about double images, drawn from the perceptions of a few squinters (e.g. by Schweigger, Klin. Untersuch über das Schielen, Berlin, 1881; by Javal, Annales d'Oculistique, lxxxv. p. 217), because the facts are exceptional at best and very difficult of interpretation. In favor of the sensationalistic or nativistic view of one such case, see the important paper by Von Kries, Archiv f. Ophthalm., xxiv. 4, p. 117.
[243] Physiologische Untersuchungen im Gebiete der Optik, v.
[244] Cf. E. Mach, Beiträge zur Analyse der Empfindungen, p. 87.
[245] Cf. V. Egger, Revue Philos., xx. 488.