~g 2 NORMAL HISTOLOGY. 



tion of the peripherally situated anterior epithelium at the equator. 



They are elongated compressed six-sided prisms varying in size 



with their position ; those at the 



FIG. 383. periphery of the lens are the 



largest (12 mm. in length by 

 10-12 n in breadth), their size 

 decreasing towards the centre. 

 In the young lens all the fibres 

 contain oval nuclei, but in the 

 adult organ only those recently 

 formed lying in the vicinity of 



FIG. 384. 



Portions of human crystalline lens : A , section 

 through periphery at equator; a, anterior capsule ; 

 b, anterior epithelium converted into lens-fibres (/) 

 at equator (z) ; , nuclei of young lens-fibres. B, 

 fragment of anterior capsule with adherent epi- 

 thelium, viewed from under surface ; h, capsule ; e, 

 epithelial cells. 



Fibres of human crystalline lens : A , 

 portions of young isolated fibres ; B, fibres 

 in transverse section. . 



the equator possess these. The fibres constituting the softer 

 cortical zone have smooth straight contours, while those of 

 the central part display a finely-serrated outline and are with- 

 out nuclei. The lens-fibres are united by albuminous cement- 

 substance, which, after suitable maceration, is dissolved, so that the 

 fibres may be readily isolated ; since the amount of the cement-sub- 

 stance is less between the broader than between the narrow surfaces 

 of the fibres, after suitable maceration the lens evinces a disposition 

 to separate into concentric lamellae, somewhat after the fashion of 

 an onion. The apposition of the ends of the fibres takes place along 

 definite lines which appear on the anterior and posterior surfaces of 

 the lens as stellate figures, the lens-stars. In the simpler con- 

 ditions of the new-born child, as well as in most mammalia, each star 

 consists of three rays, one of which in the anterior star is directed 

 upward, while the others are disposed at an angle of 120 down and 

 outward ; in the posterior star the rays form an angle of 60 with 

 those of the anterior surface, so that the figures of both surfaces 



