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The smaller segment, which forms about one sixth of the whole, is set upon the larger and forms the projecting transparent portion in front. Yellow spot. 2. Blind spot. 3. Retina. 4. Choroid coat. 5. Sclerotic coat. 6. Crystalline lens. 7. Suspensory ligament. 8. Ciliary processes and ciliary muscle. 9. Iris containing the pupil. 10. Cornea. 11. Lymph duct. 12. Conjunctiva. 13.
The opening in the fore part of this opaque coat is filled by the transparent cornea, which resembles a watch crystal in shape, and is received into a groove in the front part of the sclerotic coat in the same manner that a watch-glass is received into its case. But for this arrangement light could not gain admission to the eye.
The cornea, a clear, transparent, circular disk, fits into the sclerotic, somewhat as the crystal fits into the metallic case of a watch, forming a covering for its dial. It projects from the general contour of the eyeball, not unlike a rounded bay-window, and is often spoken of as the "window of the eye." Lining the inner surface of the sclerotic is the second coat, the choroid.
The third book of the Compendium opens with several chapters on the anatomy and physiology of the eye and the phenomena of vision. The conjunctiva 2. The albuginea or sclerotic 3. The cornea 4. though the definitions are not in all cases quite clear and definite.
Jessop mentions the case of a child of eight who suffered a blow on the eye from a fall against a bedpost, followed by compound rupture of the organ. The wound in the sclerotic was three or four lines in length, and the rent in the conjunctiva was so large that it required three sutures. The chief interest in this case was the rapid and complete recovery of vision.
The cornea arises from the sclerotic tunic, the uvea and secundina take their origin from the pia mater, and the conjunctiva from a thin pellicle or membrane which covers the exterior of the cranium and is nourished by a transudation of the blood through the coronal suture.
On the right side, in front of the external half of the sclerotic, was observed a semilunar fold with the concavity inward, and which projected much more when the lower lid was depressed. When the eyelid rolled inward the fold rolled with the globe, but never reached so far as the circumference of the cornea and did not interfere with vision.
Sclerotic, retina, choroid, vitreous humour, lens, aqueous humour, all are present.
If the finger be placed in cold or warm water the temperature appears to rise when a red glass is held in front of the eyes. Experiment 174. Formation of an inverted image on the retina. Take a freshly removed ox-eye; dissect the sclerotic from that part of its posterior segment near the optic nerve.
The real truth is that I was about written out in the matter of visitations, and needed a reinforcement of my uncanny vein, which, far from being varicose, had become sclerotic, so dry had it been pumped by the demands to which it had been subjected by a clamorous, mystery-loving public.
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