. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ORGAN OF SIGHT IN FISHES. 333 217 P c: c L. :i.^nilled, showing inter- Lied margiDS. ccxiii meridians of a globe, to two opposite points or poles of tlie sphe- roid : in the Sahnonidce and Shark, they converge to a linear tract or septum at each pole, as in fig 218. In the fibres of the lens of a cod Brewster discovered the marginal teeth, like those of rack-work, by which the fibres are interlocked together, as in fig. 217. This acute observer computes five millions of fibres and sixty- two thousand five hruidred mil- l
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ORGAN OF SIGHT IN FISHES. 333 217 P c: c L. :i.^nilled, showing inter- Lied margiDS. ccxiii meridians of a globe, to two opposite points or poles of tlie sphe- roid : in the Sahnonidce and Shark, they converge to a linear tract or septum at each pole, as in fig 218. In the fibres of the lens of a cod Brewster discovered the marginal teeth, like those of rack-work, by which the fibres are interlocked together, as in fig. 217. This acute observer computes five millions of fibres and sixty- two thousand five hruidred mil- lions of teeth in the lens of a cod : yet in the living and fresh state this organ is transparent. The radiatino; fibres and elona:- ated cells of the hyaloid tissue,' with the interstitial ' vitreous hiunour,' present a firmer con- sistency than in the human eye, and show their intimate structure and arrangement more clearly under the microscope than in Mammalia. The membranes situated between the retina and sclerotica, called collectively ' choroid tunic,' are three in num- ber : the external layer in Osseous Fishes, called' mem- hrana argentea^ fig. 216, e, is composed chiefly of micro- scopical acicular crystals reflecting a silvery, or some - times a golden lustre, with a delicate cellular basis, which assumes more firmness where it is continued upon the iris. The second or middle layer is the ' membrana vasculosa,'' seu ' Halleri,^ ib. f, and, as its name implies, is the chief seat of the ramifications of the choroid vessels: it also supports the ciliary nerves. The 218. Arrangem 11 f. 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 Owen, Richard, 1804-1892; Cornell University. College of Veterinary Medicine. Flower-Sprecher Veterinary Library. fmo. London, Longmans, Green
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