. The anatomy and physiology of the human body. Containing the anatomy of the bones, muscles, and joints; and the heart and arteries . he rays for transmission and reflection would not beperceptible, did the converging powers of the cornea and lensbring the focus of the rays exactly to the surface of the re-tina ; but as the focus is formed at e, some way before the re-tina, the rays have decussated and spread out again before theyform the image upon the bottom of the eye. Instead, there-foie, of forming an accurate image, they are spread out intoconcentric circles; or in a lesser degree, the
. The anatomy and physiology of the human body. Containing the anatomy of the bones, muscles, and joints; and the heart and arteries . he rays for transmission and reflection would not beperceptible, did the converging powers of the cornea and lensbring the focus of the rays exactly to the surface of the re-tina ; but as the focus is formed at e, some way before the re-tina, the rays have decussated and spread out again before theyform the image upon the bottom of the eye. Instead, there-foie, of forming an accurate image, they are spread out intoconcentric circles; or in a lesser degree, the person experi-ences a confused outline of the object, which becomes sur-rounded with several rings or false outlines.* * Qyfits of easy transition, it was not meant by Sir Isaac Newton that the raysmust necessarily be transmitted tlirough every pellucid medium, and at anyobliquity of incidence, but only that the ray was more easily transmitted, andmore difficultly reflected; nor was it meant that, during itsj?^ of easy reflection^it was absolutely incapable of beings transmitted, but only more readily rCfleeted than C 20 )CHAP. II. OF HIE COATS OF THE EYE. The coats of the eye are to be divided into three classes, 1. The anterior and external coats, viz. The conjunctivaand the albuginea. 2. The proper coats, viz. The sclerotica, the choroides, the RETINA., 3. The transparent tunics of the eye. As the first class belongs to the external apparatus of thee3e, we shall begin with the proper coats. Speaking generally, and without considering the minuterdivisions of anatomists, we may say, that there are three pro-per coats of the eye, viz. the sclerotic coat, giving strength;the CHOROID COAT, being the vehicle of the chief vascularstructure of the eye ; and the retina, or expanded nerve, be-ing the organ itself. These are the proper coats of the eye. Although many of these coats may be capable of being di-vided by the art of the anatomist, either by the knife, by injec
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Keywords: ., bookcentury1800, bookidanatomyphysiolog, booksubjecthumananatomy
