. An introduction to zoology [microform] : for the use of high schools. Zoology; Zoologie. e of irses n to ,the ans- the eat- ir of coat. HIGH SCHOOL zoology. 35 43. Tlio cxaininution of tlio ])ull> itsolf (b^ig. 13)a(i|uo ])art tlio Hulorotio. Witliin tliis is tlio second coat, tlio choroid, wliich cliiefly s(;rv(5S to distrilmto tlio Mood witliin tlio bull*, and to form a dark backgrouiul for the retina, but anteriorly forms a muscular screen—the iris, ptu'forated by tlio pupil, through which the amount of li^lit admitted to the sensitive part of eye may be regulated by the iris. Sus
. An introduction to zoology [microform] : for the use of high schools. Zoology; Zoologie. e of irses n to ,the ans- the eat- ir of coat. HIGH SCHOOL zoology. 35 43. Tlio cxaininution of tlio ])ull> itsolf (b^ig. 13)a(i|uo ])art tlio Hulorotio. Witliin tliis is tlio second coat, tlio choroid, wliich cliiefly s(;rv(5S to distrilmto tlio Mood witliin tlio bull*, and to form a dark backgrouiul for the retina, but anteriorly forms a muscular screen—the iris, ptu'forated by tlio pupil, through which the amount of li^lit admitted to the sensitive part of eye may be regulated by the iris. Suspcmded from the junction of the choroid and iris by a special ciliary muscle, is the lens u globular transparent body which changes tlie course of the ravs of light admitted to the 'eye, and casts an inverted image on the retina or nervous coat, which lines the whole of the choroid coat, and is separat- ed from the lens by th ; fluid and transparent vitreous humor. The optic nerve which terminates in the re- tina, must therefore pierce both the sclerotic and chor- oid coats to do so, and in- deed it perforates the re- tina also, for its fibres form the innermost of the several layers of which the retina Fig. 14.—Diai,'ramniatiG Section of Retina of jy coiUDOSed young Catfish, vinn 1. X400. 1, layer of optio nerve fibres ; 2, of gan!,'lioii cells ; S, internal molecular, 4, internal ^'ranu- liiror },'an,!,'lionic layer (con tainiii;,' nuclei of Mul- ler's fibres); 5, external molecular, (i, external granularlayer,containingnucleiof the rodsand cones, 8. but separated from them by the ex- ternal limitinjf membrane, 7; 9, pigmentary retinal epithelium. 44. Study of the develop- ment of the eye sliowa that the retina is really an outgrowth of the brain, which like the brain has .a cavity, one wall of which 1' ;i :j. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illu
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
