602 THE TISSUES. 



and, being here less coherent than on their largest surfaces, they 

 are more easily separated into laminae in this direction. 



In the separate lamellae, both the superficial and the deeper tubes 

 generally radiate from the centre of the lens towards the margin, 

 and then curve round upon the other surface, anterior or posterior; 

 but never extend through the entire semi-circumference of the 

 lens. Indeed, a peculiar appearance called the "star" is produced 

 where they terminate on both surfaces of the lens, as shown "by 



Fig. 434. 





Lens of the adult (after Arnold), to show the "star." 1 Anterior aspect. 2. Posterior aspect. 



(Kittiker.) 



Fig. 484. In these there are no tubes, but a substance partly clear 

 and partly finely granular. 



The capsule of the lens is formed of simple membrane, and is 

 perfectly transparent and very elastic. It admits neither vessels 

 nor nerves to the completely inclosed lens. It is, however, readily 

 permeable to fluids; and it is the transmission through it, after 

 death, of the aqueous humor of the eye, that mainly gives rise to 

 the "liquor Morgagni" this not being a normal condition, as has 

 been supposed. A single layer of clear, polygonal, epithelial cells, 

 however, covers the anterior half of the inner surface of the cap- 

 sule; and these, disintegrated, also help to form the "liquor." 



Chemical analysis (of the lens) detects the presence of crystalline, 

 described on page 97. It contains about 58 per cent, of water. 



The crystalline lens is not vascular at any period of its develop- 

 ment. The capsule is so, however, during early foetal existence; 

 the central artery of the retina expanding upon its posterior layer 

 (after having traversed the vitreous humor), and sending branches 



