STRUCTURE OF LENS. 561 



The shape of the lens varies at different times of life, being 

 nearly spherical in the infant and tending to become less convex 



FIG. 220. 



Fragment of lens teased out to show the separate fibres. (Cadiat.) 

 a, 6, and c, show fibres with different-sized nuclei. 



in old age (v. Fig. 217). The lens is developed from the outer 

 layer of the embryo by the gradual thickening and growing in- 



47 



