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This diagram shows a side view of the right eye of man. a.c., central artery; a.h., aqueous humor; b., blind spot, the entrance of the optic nerve; c, conjunctiva; ch., choroid layer of the eye-ball; c.l., crystalline lens; c.m.c., circular fibers of the ciliary muscles; c.m.r., radial fibers of the ciliary muscles; co., cornea, the transparent portion of the sclerotic; c.p., ciliary process; c.s., canal of Schlemm, a lymphatic vessel; fo., fovea centralis, the point of clearest vision; o.n., optic nerve; o.s., ora serrata, the anterior wavy margin of the visual portion of the retina; r, the retinal layer; sc., sclerotic layer; sh., sheath of theoptic nerve; v.h., vitreous humor.

Human Eye

This diagram shows a side view of the right eye of man. a.c., central artery; a.h., aqueous humor; b.,…

"Diagrams illustrating two stages in the development of the vertebrate eye. A, showing the relation of the ectoderm, the brain vesicle, and the optic vesicle. The right side of the figure shows a later stage than the left. B, later stage, showing the lens, eye-ball and retina in position. b.v., brain vesicle formed by the invagination oof the ectoderm (ect.); l, lens; mes., mesodermal tissue; o.n., optic nerve; o.s., optic stalk; o.v., optic vesicle, a portion of the brain vesicle; r, retinal layer; v.h., interior of eye-ball which comes to contain the vitreous humor." — Galloway

Vertebrate Eye

"Diagrams illustrating two stages in the development of the vertebrate eye. A, showing the relation…

"Section through the lateral eye of Euscorpius italicus. lens, Cuticular lens. nerv.c, Retinal cells (nerve-end cells). rhabd, Rhabdomes. nerv.f, Nerve fibes of the optic nerve. int, Intermediate cells (lying between the bases of the retinal cells)." — The Encyclopedia Britannica, 1910

Euscorpius Italicus

"Section through the lateral eye of Euscorpius italicus. lens, Cuticular lens. nerv.c, Retinal cells…

"Diagram illustrating the points at which incident rays meet the retina. xx, optic axis; k, first nodal point; k', second nodal point; b, point where the image of B would be formed, were the eye properly accommodated for it; a, the retinal point where the image of A would be formed." —Martin, 1917

Retina

"Diagram illustrating the points at which incident rays meet the retina. xx, optic axis; k, first nodal…

Diagram showing relations of the neurons and sensory epithelium in the retina. labels: E, epithelial layer of nucleated rode and cone cells, rods being directed towards choroid coat of retina; N1, neurons of first series receiving by their dendritic impulses from the rod and cone cells and transmitting them by their axons to N2, the neurons of the second series. The axons of the neurons of the second series pass along the inner surface of the retina to the blind spot, where they unite to form the optic nerve.

Neurons and Sensory Epithelium in the Retina

Diagram showing relations of the neurons and sensory epithelium in the retina. labels: E, epithelial…

The right retina as it would be seen if the front part of the eyeball with the lens and vitreous humor were removed. The white disk to the right marks the entry of the optic nerve (blind spot); the lines radiating from this are the retinal arteries and veins. The small central dark patch is the yellow spot, the region of most acute vision.

Retina Blind Spot

The right retina as it would be seen if the front part of the eyeball with the lens and vitreous humor…

Diagram of the structure of the human retina. Labels: I, pigment layer; II, rod and cone layer; R, rods; C, cones; III-IX, intraretinal nerve-elements; X, axons which pass to optic nerve.

Retinal Structure

Diagram of the structure of the human retina. Labels: I, pigment layer; II, rod and cone layer; R, rods;…

"Diagrams showing some of the stages in the increasing complexity of the simple eye in Invertebrates. A, simple pigment spot in epithelium having nerve-endings associated with pigment cells (as in some medusae); B, pigment cells in a pit-like depression (as in Patella); C, with pin-hole opening and vitreous humor in cavity (as in Trochus); D, completely closed pit, with lens and cornea (as in Triton and many other Mollusks); E, pigment area elevated instead of depressed, lens of thickened cuticula (as in the Medusa, Lizzia); F, retinal cells more highly magnified. ep., epidermis; f, nerve fibre; l, lens; op, optic nerve; p, pigment cells; r, retina; v.h., vitreous humor." -Galloway, 1915

Invertebrate Simple Eye

"Diagrams showing some of the stages in the increasing complexity of the simple eye in Invertebrates.…

Transverse vertical section of the eyeball of a human embryo of four weeks. The anterior half of the section is represented: pr, the remains of the cavity of the primary optic vesicle; p, the inner part of the outer layer forming the retinal pigment; r, the thickened inner part giving rise to the columnar and other structures of the retina; v, the commencing vitreous humour within the secondary optic vesicle; v', the ocular cleft through which the loop of the central blood vessel, a, projects from below; l, the lends with a central cavity.

Eye of Fetus of Four Weeks

Transverse vertical section of the eyeball of a human embryo of four weeks. The anterior half of the…

Plan of the retinal neurons.

Plan of the Retinal Neurons

Plan of the retinal neurons.

A, section through the open eyepit of a limpet. B, the two kinds of retinal cells, pigmented and sensory.

Eyepit of Limpet

A, section through the open eyepit of a limpet. B, the two kinds of retinal cells, pigmented and sensory.