. The microscope and its revelations. . 671.—Section of shell of Echinusshowing the calcareous network ofwhich it is composed: <t a, portionsof a deeper layer. FIG. 672.—Transverse section of cen-tral portion of spine of Heterocen-t rot us, showing its more open net-work. smaller plates interposed between the larger spine-bearing plates ofits box-like shell. If the entire disc be cut off. and be mountedwhen dry in Canada balsam, the calcareous rosette may be seensufficiently well ; but its beautiful structure is better made out whenthe animal membrane that incloses it has been got rid of by
. The microscope and its revelations. . 671.—Section of shell of Echinusshowing the calcareous network ofwhich it is composed: <t a, portionsof a deeper layer. FIG. 672.—Transverse section of cen-tral portion of spine of Heterocen-t rot us, showing its more open net-work. smaller plates interposed between the larger spine-bearing plates ofits box-like shell. If the entire disc be cut off. and be mountedwhen dry in Canada balsam, the calcareous rosette may be seensufficiently well ; but its beautiful structure is better made out whenthe animal membrane that incloses it has been got rid of by boilingin a solution of caustic potass; and the appearance of one of thefive segments of which it is composed, when thus prepared, is shownin fig. 674. The most beautiful display of this reticulated structure, however,is shown in the conformation of the spines of Echinus, Cidfiris, &c.,in which it is combined with solid ribs or pillars, disposed in such amanner as to increase the strength of these organs, a, regular andelabo
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
