THE EYE. 249 



the removal of the lens, the form and attachment of 

 the iris are readily seen. 



In the same half of the eye, the layers of the choroid 

 may be demonstrated. For this purpose the retina is 

 pulled off, and the pigmented cells, which are apt to ad- 

 here to the inner surface of the choroid, are brushed or 

 scraped off. The choroid is now removed by breaking 

 its attachment to the sclero-corneal junction, with the 

 handle of the forceps, and carefully pulling it away 

 from the sclera. This will be found to be an easy 

 matter until the optic-nerve entrance is reached. Here, 

 on account of its blending with the sclera, .it is to be 

 cut away with scissors. The removed choroid is now 

 immersed in a dish of water when the membrana supra- 

 choroidea will be seen as a brown, loose tissue floating 

 from the surface of the choroid. Bits of this are pulled 

 off with the forceps, stained with haematoxylin, floated 

 smoothly on to a slide immersed in water, and mounted 

 in glycerin. The floating shreds of the supra-choroidea 

 which remain after suitable specimens have been ob- 

 taind, should now be pulled from the eye, when the 

 vascular layer of Haller will come into view. 



The separation of the three remaining layers is not 

 easy under the most favorable conditions, and is espe- 

 cially difficult in the eye of the ox and sheep, where the 

 layers are rendered more complicated and difficult of 

 separation by the presence of a mass of interlacing fibres. 

 Haller's layer, however, and the membrana chorio- 

 capillaris may be, with care, stripped off in pieces suffi- 

 ciently thin for demonstration ; sometimes a fragment 

 will be obtained, which, especially at the edges, will show 



