. Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget ... Biology; Physiology; Plant physiology; Natural theology. 400 THE SENSORIAL FUNCTIONS. line lens of the Cod, to which he was led by noticing some remarkable optical appearances presented by thin layers of this substance when transmitting polarised light. He found that the hard central portion is composed of a succession of concentric, and perfectly transparent, sphe- roidal laminae, the surfaces of which, though apparently smooth, have the same kind of iri- descence as mother-of-pearl, and


. Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget ... Biology; Physiology; Plant physiology; Natural theology. 400 THE SENSORIAL FUNCTIONS. line lens of the Cod, to which he was led by noticing some remarkable optical appearances presented by thin layers of this substance when transmitting polarised light. He found that the hard central portion is composed of a succession of concentric, and perfectly transparent, sphe- roidal laminae, the surfaces of which, though apparently smooth, have the same kind of iri- descence as mother-of-pearl, and arising from the same cause ; namely, the occurrence of re- gularly arranged lines, or strice* These lines, which mark the edges of the separate fibres composing each lamina, converge like meridians from the equator to the two poles of the sphe-. roid, as is shown in Fig. 431. The fibres them- selves are not cylindrical, but flat; and they taper at each end as they approach the points of convergence. The breadth of the fibres in the most external layer, at the equator, is about the 5,500th of an inch. The observation of another optical phenomenon, of a still more delicate kind, * See vol. i. p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Roget, Peter Mark, 1779-1869. London : W. Pickering


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