222 PKACTICAL HISTOLOGY [XXIX 



of connective tissue with pigment cells, and with 

 numerous blood vessels (note the transversely cut 

 vessels in the -peripheral part of the iris) and nerve 

 bundles ; (d) a wedge-shaped bundle of transversely 

 cut muscle fibres near the pupillary margin, the 

 sphincter pupillae ; (e) a rather indistinct anterior 

 limiting membrane. 



The cornea, consisting of, (a) the anterior epi- 

 thelium continuous with that of the conjunctiva ; note, 

 the external layer of flattened but nucleated cells, the 

 middle layer of two or three polyhedral cells, and the 

 inner layer of a single row of columnar cells ; (b) the 

 connective tissue arranged in Iamina3, with flattened 

 cells between them, it forms an inconspicuous anterior 

 basement membrane ; (c) the posterior elastic mem- 

 brane (membrane of Descemet), thick and hyaline, 

 with very sharp outlines : (d) the posterior epithelium 

 of flattened cells. 



2. Lens. Take an ox's or sheep's lens which has 

 been in potassium bichromate '2 p.c. for a week. The 

 junctional lines of the lens fibres will be seen as a star ; 

 the fibres readily peel off in laminse. 



3. Antero-posterior section of lens (Miiller's fluid, 

 cut frozen); stain with picrocarmine, mount in glycerine. 

 Note 



The hyaline capsule. 



The columnar epithelium of the anterior surface of 

 the lens; at the sides these rapidly but gradually 

 elongate into fibres. 



At the sides, the nuclei of the fibres forming an 

 irregular band. 



