CHAPTER IX ON CONCRETIONS, SPICULES, AND SPICULAR SKELETONS
406 There is much information regarding the chemical composition and mineralogical structure of shells and other organic products in H. C. Sorbyãs Presidential Address to the Geological Society (Proc. Geol. Soc. 1879, pp. 56ã93); but Sorby failed to recognise that association with ãorganicã matter, or with colloid matter whether living or dead, introduced a new series of purely physical phenomena.
407 Vesque, Ann. des Sc. Nat. (Bot.) (5), XIX, p. 310, 1874.
408 Cf. KûÑlliker, Icones Histiologicae, 1864, pp. 119, etc.
409 In an interesting paper by Irvine and Sims Woodhead on the ãSecretion of Carbonate of Lime by Animalsã (Proc. R. S. E. XVI, 1889, p. 351) it is asserted that ãlime salts, of whatever form, are deposited only in vitally inactive tissue.ã
410 The tube of Teredo shews no trace of organic matter, but consists of irregular prismatic crystals: the whole structure ãbeing identical with that of small veins of calcite, such as are seen in thin sections of rocksã (Sorby, Proc. Geol. Soc. 1879, p. 58). This, then, would seem to be a somewhat exceptional case of a shell laid down completely outside of the animalãs external layer of organic or colloid substance.
411 C. R. Soc. Biol. Paris (9), I, pp. 17ã20, 1889; C. R. Ac. Sc. CVIII, pp. 196ã8, 1889.
412 Cf. Heron-Allen, Phil. Trans. (B), vol. CCVI, p. 262, 1915.
413 See Leduc, Mechanism of Life (1911), ch. X, for copious references to other works on the artificial production of ãorganicã forms.
414 Lectures on the Molecular Asymmetry of Natural Organic Compounds, Chemical Soc. of Paris, 1860, and also in Ostwaldãs Klassiker d. ex. Wiss. No. 28, and in Alembic Club Reprints, No. 14, Edinburgh, 1897; cf. Richardson, G. M., Foundations of Stereochemistry, N. Y. 1901.