. The fundus oculi of birds, especially as viewed by the ophthalmoscope [microform] : a study in comparative anatomy and physiology. Ophthalmoscopy; Eye; Ophtalmoscopie; Oiseaux; Oeil; Birds. 22 THE FUNDUS OCULI OF BIRDS in food-searching in such u fashion that ?hey are to see one object very distinctly iiNd neighboring objects (in a restricted field of vision) more distinctly than is permitted l>y the comparatively insensitive retina of the roniaininj; fundal areas. IiifulaiHiiullary angle. The relations, es- JKcially of fundal position, between the optic nerve entrance, the pect
. The fundus oculi of birds, especially as viewed by the ophthalmoscope [microform] : a study in comparative anatomy and physiology. Ophthalmoscopy; Eye; Ophtalmoscopie; Oiseaux; Oeil; Birds. 22 THE FUNDUS OCULI OF BIRDS in food-searching in such u fashion that ?hey are to see one object very distinctly iiNd neighboring objects (in a restricted field of vision) more distinctly than is permitted l>y the comparatively insensitive retina of the roniaininj; fundal areas. IiifulaiHiiullary angle. The relations, es- JKcially of fundal position, between the optic nerve entrance, the pecten, and the areas of distmct vision are, as we have nireadv seen, of some biological importance. I'pon the locality of the macular regions depend, in great measure, the qualify and precision of the eyesight o. each particular bird. That one may facilitate references to the location in the eyegrou'id of the retinal band the writer proposes to measure what he has the nifulapapillary angle {in/ula, a band, papilla, the optic <lisc), made by the junction of the major axis of the ovoid eiitrnnte of the optic nerve prolonged until it meets the retinal band on the nasal side of the point of contact. In the case of the Hudsonian Curlew (see Fig. 125) it is 50°. The Optic Nerve of Birds In all Vertebrates the oi)tic nerve has the form of a cord, sometimes very short, as in Birds, and occasionally long, as in Man. which extends from the optic foramen to the posterior segment of the eyeball, where its expansion forms the retina. In Birds, whose ocular movements displace the eyeball very little, the nerve takes the form of a short, almost rectilinear cord; while in animals with mobile eyes, such as the large Mamnufers, the nerve is long, round and b-sha{)ed, to follow the displacements of the posterior hemisphere without pulling or drag- ging. Its diameter greatly varies; it may reach 8 mm., as in the Whale. The rule is that it roughly corresponds in size and length to the volu
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbirds, booksubjecteye
