[532] “It has been suggested, and I think in some quarters adopted as a dogma, that the formation of successive septa [in Nautilus] is correlated with the recurrence of reproductive periods. This is not the case, since, according to my observations, propagation only takes place after the last septum is formed;” Willey, Zoological Results, p. 746, 1902.
[533] Cf. Woodward, Henry, On the Structure of Camerated Shells, Pop. Sci. Rev. XI, pp. 113–120, 1872.
[534] See Willey, Contributions to the Natural History of the Pearly Nautilus, Zoological Results, etc. p. 749, 1902. Cf. also Bather, Shell-growth in Cephalopoda, Ann. Mag. N. H. (6), I, pp 298–310, 1888; ibid. pp. 421–427, and other papers by Blake, Riefstahl, etc. quoted therein.
[535] It was this that led James Bernoulli, in imitation of Archimedes, to have the logarithmic spiral graven on his tomb, with the pious motto, Eadem mutata resurgam. On Goodsir’s grave the same symbol is reinscribed.
[536] The “lobes” and “saddles” which arise in this manner, and on whose arrangement the modern classification of the nautiloid and ammonitoid shells largely depends, were first recognised and named by Leopold von Buch, Ann. Sci. Nat. XXVII, XXVIII, 1829.
[537] Blake has remarked upon the fact (op. cit. p. 248) that in some Cyrtocerata we may have a curved shell in which the ornaments approximately run at a constant angular distance from the pole, while the septa approximate to a radial direction; and that “thus one law of growth is illustrated by the inside, and another by the outside.” In this there is nothing at which we need wonder. It is merely a case where the generating curve is set very obliquely to the axis of the shell; but where the septa, which have no necessary relation to the mouth of the shell, take their places, as usual, at a certain definite angle to the walls of the tube. This relation of the septa to the walls of the tube arises after the tube itself is fully formed, and the obliquity of growth of the open end of the tube has no relation to the matter.
[538] Cf. pp. 255, 463, etc.
[539] In a few cases, according to Awerinzew and Rhumbler, where the chambers are added on in concentric series, as in Orbitolites, we have the crystalline structure arranged radially in the radial walls but tangentially in the concentric ones: whereby we tend to obtain, on a minute scale, a system of orthogonal trajectories, comparable to that which we shall presently study in connection with the structure of bone. Cf. S. Awerinzew, Kalkschale der Rhizopoden, Z. f. w. Z. LXXIV, pp. 478–490, 1903.
[540] Rhumbler, L., Die Doppelschalen von Orbitolites und anderer Foraminiferen, etc., Arch. f. Protistenkunde, I, pp. 193–296, 1902; and other papers. Also Die Foraminiferen der Planktonexpedition, I, 1911, pp. 50–56.
[541] Bénard, H, Les tourbillons cellulaires, Ann. de Chimie (8), XXIV, 1901. Cf. also the pattern of cilia on an Infusorian, as figured by Bütschli in Bronn’s Protozoa, III, p. 1281, 1887.