[442] Descent of Man, II, pp. 132–153, 1871.
[443] As a matter of fact, the phenomena associated with the development of an “ocellus” are or may be of great complexity, inasmuch as they involve not only a graded distribution of pigment, but also, in “optical” coloration, a symmetrical distribution of structure or form. The subject therefore deserves very careful discussion, such as Bateson gives to it (Variation, chap. xii). This, by the way, is one of the very rare cases in which Bateson appears inclined to suggest a purely physical explanation of an organic phenomenon: “The suggestion is strong that the whole series of rings (in Morpho) may have been formed by some one central disturbance, somewhat as a series of concentric waves may be formed by the splash of a stone thrown into a pool, etc.”
[444] Cf. also Sir D. Brewster, On optical properties of Mother of Pearl, Phil. Trans. 1814, p. 397.
[445] Biedermann, W., Ueber die Bedeutung von Kristallisationsprozessen der Skelette wirbelloser Thiere, namentlich der Molluskenschalen, Z. f. allg. Physiol. I, p. 154, 1902; Ueber Bau und Entstehung der Molluskenschale, Jen. Zeitschr. XXXVI, pp. 1–164, 1902. Cf. also Steinmann, Ueber Schale und Kalksteinbildungen, Ber. Naturf. Ges. Freiburg i. Br IV, 1889; Liesegang, Naturw. Wochenschr. p. 641, 1910.
[446] Cf. Bütschli, Ueber die Herstellung künstlicher Stärkekörner oder von Sphärokrystallen der Stärke, Verh. nat. med. Ver. Heidelberg, V, pp. 457–472, 1896.
[447] Untersuchungen über die Stärkekörner, Jena, 1905.
[448] Cf. Winge, Meddel. fra Komm. for Havundersögelse (Fiskeri), IV, p. 20, Copenhagen, 1915.
[449] The anhydrite is sulphate of lime (CaSO4); the polyhalite is a triple sulphate of lime, magnesia and potash (2 CaSO4 . MgSO4 . K2SO4 + 2 H2O).
[450] Cf. van’t Hoff, Physical Chemistry in the Service of the Sciences, p. 99 seq. Chicago, 1903.
[451] Sphärocrystalle von Kalkoxalat bei Kakteen, Ber. d. d. Bot. Gesellsch. p. 178, 1885.