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MANUAL OF PHYSIOLOGY. 



but little denser than a stiff jelly. It is inclosed by a firm elastic 

 capsule, which is drawn tightly over the anterior surface, and 

 influences its shape. The lens is held in its position by a thick- 

 ened part of the soft, elastic hyaloid membrane, called the sus- 

 pensory ligament, which is attached to the anterior surface of the 

 capsule, near its margin. The lens and its capsule, together with 



FIG. 219. 



./*-. 



A further stage of the development of the lens. (Cadiat.) a, Elongating 

 epithelial cells forming lens; b, Capsule ; c, Cutaneous tissue becoming con- 

 junctiva; rf, e, Two layers of optic cup forming retina; /, Cell of mucous 

 tissue of the vitreous humor ; g, Intercellular substance ; h, Developing 

 optic nerve. 



the vitreous humor, may be said to be inclosed in the hyaloid 

 membrane, which is thickened and fixed to the capsule, and to 

 the ciliary part of the choroid. Thus any tension exercised by 

 the suspensory ligament tends to tighten the anterior part of the 

 capsule, and flatten the anterior surface of the lens. 



