THE EYE. 249 



stream of distilled water, and the eye is placed in 

 water in the sunlight. When sufficiently stained it 

 is removed from the window, fastened under water 

 to a loaded cork by a long pin passed through the 

 cornea, and a piece of the capsule of Tenon is dis- 

 sected off the globe, floated flat on to a slide, and 

 removed from Ithe fluid. After the excess of water 

 has been got rid of, the piece is covered in glycerine 

 and examined for the epithelioid markings. 



Preparations 5 and 6. Lamina fusca. The 

 epithelioid layer lining the lamina fusca is also pre- 

 pared by nitrate of silver. A square piece of the 

 sclerotic is dissected off from a fresh eye ; the convex 

 outer surface of the piece is then pressed in and made 

 concave, the previously concave inner surface being 

 made the convex one, and the piece is first dipped 

 in water, then placed for two minutes in silver solu- 

 tion, then, after being again rinsed in water, trans- 

 ferred to spirit and placed in the light, with the 

 inner surface or lamina fusca uppermost. After half 

 an hour, by which time even in diffused daylight 

 the silver will probably be reduced, although owing 

 to the natural brown color this cannot well be seen, 

 it is removed, and in twenty-four hours, or when 

 hard enough for the purpose, sections are made from 

 the brown surface, placed in water, and mounted in 

 glycerine. The pigment cells usually obscure the 

 silver markings to a certain extent. This inconve- 

 nience can be obviated by using the eye of an albino 

 rabbit. Here, moreover, the sclerotic is not too 

 thick to admit of the piece being mounted entire 

 in glycerine ; the immersion and hardening in spirit 

 are then not necessary, for the piece may be exposed 

 in water to the light, and mounted without further 

 preparation, two or three radial slits being made in 

 it if necessary with the object of causing it to lie 

 flat on the slide. 



Besides this preparation of its epithelioid layer 

 the lamina fusca may itself be displayed in an eye, 

 or portion of an eye, that has been prepared with 



