270 PRACTICAL HISTOLOGY. 



fibres of the lens, as well as for showing their ar- 

 rangement. Take the fresh eye of any animal 

 that of the ox or sheep for example and cut it 

 across into an anterior and a posterior half. Place 

 the anterior part, having removed what remains of 

 the vitreous humor, in J per cent, solution of bi- 

 chromate of potash. Then scratch through the 

 posterior capsule, which is readily ruptured and 

 curls away from the lens proper. This can easily be 

 shelled out, and is left in the fluid, the remainder 

 of the eye being rejected. The lens is allowed to 

 remain in the bichromate for two or three days, 

 being merely turned over once or twice. It will be 

 found that its substance tends both to separate along 

 the radiating lines which mark the planes of junc- 

 tion of the ends of the fibres, and also to peel into 

 concentric lamellae like the coats of an onion ; and, 

 if a piece of one of these lamellae is taken up with 

 the forceps, it will tear in the direction of the fibres 

 from one of the planes of junction of the anterior 

 surface to the corresponding plane of the posterior. 

 The fibres can be readily separated with needles in 

 a drop of the bichromate solution. For this pur- 

 pose portions should be taken both from the super- 

 ficial and from the more central parts of the lens. 

 In many of the superficial fibres a round or elon- 

 gated nucleus may be detected at one part, and since 

 the nuclei of adjacent fibres are met with in about 

 the same region, when a number of fibres are seen 

 together the nuclei lie in an irregular row. The 

 riband-like shape of the fibres may be made out at 

 parts where they are turned over so as to be seen 

 edgeways. 



Preparation 35. Sections of the Lens, For 

 cutting sections of the lens it is best to harden it in 

 Muller's fluid. The whole anterior half of an eye 

 should be put in this, the cornea having been partly 

 removed so as to enable the fluid to get freely to the 

 front as well as to the back of the lens, but the 

 capsule is not to be ruptured. After two or three 



