[402] Phil. Trans. CLVII, pp. 643–656, 1867.
[403] Sachs, Pflanzenphysiologie (Vorlesung XXIV), 1882; cf. Rauber, Neue Grundlage zur Kenntniss der Zelle, Morphol. Jahrb. VIII, p. 303 seq., 1883; E. B. Wilson, Cell-lineage of Nereis, Journ. of Morphology, VI, p. 448, 1892, etc.
[404] In the following account I follow closely on the lines laid down by Berthold; Protoplasmamechanik, cap. vii. Many botanical phenomena identical and similar to those here dealt with, are elaborately discussed by Sachs in his Physiology of Plants (chap. xxvii, pp. 431–459, Oxford, 1887); and in his earlier papers, Ueber die Anordnung der Zellen in jüngsten Pflanzentheilen, and Ueber Zellenanordnung und Wachsthum (Arb. d. botan. Inst. Würzburg, 1878, 1879). But Sachs’s treatment differs entirely from that which I adopt and advocate here: his explanations being based on his “law” of rectangular succession, and involving complicated systems of confocal conics, with their orthogonally intersecting ellipses and hyperbolas.
[405] Cf. p. 369.
[406] There is much information regarding the chemical composition and mineralogical structure of shells and other organic products in H. C. Sorby’s Presidential Address to the Geological Society (Proc. Geol. Soc. 1879, pp. 56–93); but Sorby failed to recognise that association with “organic” 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. Kölliker, Icones Histiologicae, 1864, pp. 119, etc.
[409] In an interesting paper by Irvine and Sims Woodhead on the “Secretion of Carbonate of Lime by Animals” (Proc. R. S. E. XVI, 1889, p. 351) it is asserted that “lime salts, of whatever form, are deposited only in vitally inactive tissue.”
[410] The tube of Teredo shews no trace of organic matter, but consists of irregular prismatic crystals: the whole structure “being identical with that of small veins of calcite, such as are seen in thin sections of rocks” (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 animal’s external layer of organic or colloid substance.
[411] C. R. Soc. Biol. Paris (9), I, pp. 17–20, 1889; C. R. Ac. Sc. CVIII, pp. 196–8, 1889.