654 ON CONCRETIONS, SPICULES, ETC. [ch. 



shewing, as they grew larger, the typical Brownian movement. So 

 far, much the same phenomena were witnessed whether the solution 

 were albuminous or not, and similar appearances indeed had been 

 witnessed and recorded by Gustav Rose, so far back as 1837*; but 

 in the later stages the presence of albuminoid matter made a great 

 difference. Now, after a few days, the calcium carbonate was seen 

 to be deposited in the form of large rounded concretions, each with 

 a more or less distinct central nucleus and with a surrounding 

 structure at once radiate and concentric; the presence of concentric 

 zones or lamellae, alternately dark and clear, was especially charac- 

 teristic. These round " calcospherites " shewed a tendency to 

 aggregate in layers, and then to assume polyhedral, often regularly 

 hexagonal, outhnes. In this latter condition they closely resemble 

 the early stages of calcification in a molluscan (Fig. 296), or still 

 more in a crustacean shell f; while in their isolated condition they 



* Cf. Quincke, Ueber unsichtbare Flussigkeitsschichten, etc., Ann. der Physik 

 (4), VII, pp. 631-682, 701-744, 1902. 



t See for instance other excellent illustrations in Carpenter's article "Shell," 

 in Todd's Cyclopcedia, iv, pp. 556-571, 1847-49. According to Carpenter, the 

 shells of the mollusca (and also of the Crustacea) are "essentially composed of 

 cells, consolidated by a deposit of carbonate of lime in their interior." That is 

 to say, Carpenter supposed that the spherulites or calcospherites of Harting were, 

 to begin with, just so many living protoplasmic cells. Soon afterwards, however, 

 Huxley pointed out that the mode of formation, while at first sight "irresistibly 

 suggesting a cellular structure. . .is in reality nothing of the kind," but "is simply 

 the result of the concretionary manner in which the calcareous matter is deposited"; 

 ibid. art. "Tegumentary organs," v, p. 487, 1859. Quekett (Lectures on Histology, 

 II, p. 393, 1854, and Q.J. M.S. xi, pp. 95-104, 1863) supported Carpenter; but^ 

 Williamson (Histological features in the shells of the Crustacea, Q.J. M.S. viii, 

 pp. 35-47, 1860) amply confirmed Huxley's view, which in the end Carpenter 

 himself adopted {The Microscope, 1862, p. 604). A like controversy arose later 

 in regard to corals. Mrs Gordon (M. M. Ogilvie) asserted that the coral was built 

 up "of successive layers of calcified cells, which hang together at first by their 

 cell-walls, and ultimately, as crystalline changes continue, form the individual 

 laminae of the skeletal structures" {Phil. Trans, clxxxvii, p. 102, 1896): whereas 

 von Koch had figured the coral as formed out of a mass of " Kalkconcremente " 

 or "crystalline spheroids," laid down outside the ectoderm, and precisely similar 

 both in their early rounded and later polygonal stages (though von Koch was not 

 aware of the fact) to the calcospherites of Harting (Entw. d. Kalkskelettes von 

 Astroides, Mitth. Zool. St. Neapel, iii, pp. 284-290, pi. xx, 1882). Lastly, W. H. 

 Bryan finds all ordinary corals {Hexacoralla) to be mineral aggregates formed by 

 "spherulitic crystallisation," due in turn to the presence of a colloid matrix secreted 

 by certain areas of ectoderm; see Prof . R.S. Queensland, Lu, pp. 41-53, 1940; Univ. 

 of Queensland Papers, Geology, u, 4 and 5, 1941. Cf. J. E. Duerden, On Siderastraea . 

 Carnegie Inst. Washington, 1904, p. 34. 



