36 



ELEMENTS OF HISTOLOGY, [ciiap. xxxvin. 



margin of the lens, where its cells, gradually elonga- 

 ting, pass into the lens-fibres. The nuclei of these 

 lie in a curved plane belonging to the anterior half of 

 the lens : this is the nuclear zone. The lens-substance 

 consists of the lens-fibres. These are band-like, hexa- 

 gonal in transverse section ; their outline is beset 

 with numerous fine ridges and furrows, which in 

 neighbouring fibres, fitting the one into the other, 

 form a firm connection between the fibres (Valentin, 

 Henle, Kolliker, and others). The fibres of the 

 peripheral portion are broader and thicker, and their 

 substance less firm than those of the centre i.e., of 

 the lens-nucleus. The substance of the lens-fibres is 

 finely granular and delicately and longitudinally 

 striated. 



430. The lens fibres (Fig. 156) are arranged in 

 concentric lamellae, each consisting of a single layer of 

 fibres joined by their broad 

 surfaces. Each fibre is slightly 

 enlarged at the extremities ; 

 and in each lamella the fibres 

 extend from the anterior to the 

 posterior surface. Their ex- 

 tremities are in contact with 

 the ends of the fibres of the 

 same lamella in the sutures, or 

 the rays of the so-called lens 

 stars. In the lens of the new- 

 born child, the stars of both 

 anterior and posterior lamellae 

 possess three such rays, while 

 in the adult each of these rays 

 has secondary rays. In these 

 rays there is a homogeneous thin layer of an albu- 

 minous cement substance ; a similar substance in 

 minute quantity is also present between the lamellae, 

 and in it occur smaller or larger clefts and channels, 



Fig. 156. From a Section 

 through the Lens of 

 Dog. 



Showing four lamellae ; in 

 each the component lens- 

 fibres are cut across ; they 

 appear as flattened hexa- 

 gons. (Atlas.) 



