. The microscope and its revelations. ws a tendency tosplit into thin lamina1 along the lines of striation. whilst we occa-sionally meet with an excessively thin natural lamina lying betweenthe thicker prismatic layers, withone of which it would haveprobably coalesced but for someaccidental cause which preservedits distinctness. That the prismsare not formed in their entirelength at once, but that they areprogressively lengthened andconsolidated at their lower ex-tremities, would appear alsofrom the fact that where the shell presents a deep colour (as Df . . L . FIG. 695.—Section of the shell
. The microscope and its revelations. ws a tendency tosplit into thin lamina1 along the lines of striation. whilst we occa-sionally meet with an excessively thin natural lamina lying betweenthe thicker prismatic layers, withone of which it would haveprobably coalesced but for someaccidental cause which preservedits distinctness. That the prismsare not formed in their entirelength at once, but that they areprogressively lengthened andconsolidated at their lower ex-tremities, would appear alsofrom the fact that where the shell presents a deep colour (as Df . . L . FIG. 695.—Section of the shell of Pinna in / tuna mgmna) this colour in the direction of its prisms. is usually disposed in distinct strata, the outer portion of each layer being the part most deeplytinged, whilst the inner extremities of the prisms are almost colourless. This prismatic arrangement of the carbonate of lime in theshells of Pinna and its allies has been long familiar to coiicholo-gists, and regarded by them as the result of crystallisation. When.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
