IX] ON CONOSTATS 659 



Where we have simple aggregates of two or three calcospherites 

 the resulting figure is that of so many contiguous soap-bubbles. 

 In other cases composite forms result which are not so easily ex- 

 plained, but which, if we could only account for them, would be 

 of very great interest to the biologist. For instance, when smaller 

 calcospheres seem, as it were, to invade the substance of a larger one, 

 we get curious conformations which somewhat resemble the outlines 

 of certain diatoms (Fig. 301). Another curious formation, which 

 Harting calls a '"conostat," is of frequent occurrence, and in it we 



Fig. .'iUl. Composite calcospheres. Alter Harting. 



see at least a suggestion of analogy with the configuration which, 

 in a protoplasmic structure, we have spoken of as a "collar-cell." 

 The conostats, which are formed in the surface layef of the solution, 

 consist of a portion of a spheroidal calcospherite, whose upper part 

 is continued into a thin spheroidal collar of somewhat larger radius 

 than the solid sphere; but the precise manner in which the collar, 

 is formed, possibly around a bubble of gas, possibly about a vortex- 

 like diffusion-current, is not obvious. 



Among these various phenomena, the concentric striation of the 

 calcospherite has acquired a special interest and importance*. It 

 is part of a phenomenon now widely known under the name of 

 "Liesegang's Ringst." 



* Cf. Harting, op. cit. pp. 22, 50: "J'avais cru d'abord que ces couches 

 concentriques etaient produites par I'alternance de la chaleur ou de la lumiere, 

 pendant le jour et la nuit. Mais I'experience, expressement instituee pour 

 examiner cette question, y a repondu negativement." 



f R. E. Liesegang, Ueber die Schichtungen hei Diffusionen, Leipzig, 1907, and 

 earlier papers. A periodic precipitate is said to have been first noticed (on filter- 

 paper) by Runge, in 1885; cf. Quincke, Ueber unsichtbare Fliissigkeitsschichten, 

 Ann. d. Physik (4), vii, pp. 643-7, 1902. On a very minute periodicity in the 

 so-called Hookham's crystals, formed by crystallising copper sulphate and salicin 

 in strong syrup, see Rayleigh, Collected Papers, vi, p. 661: "There is much here,"' 

 says Rayleigh, '"to excite admiration and perj)lexity." 



