XXVI.] THE EYE. 273 



d. The molecular layer, consisting of a close 

 network of fine fibrils ; under a moderately 

 high power it may appear simply granular. 



c. The inner nuclear layer, consisting of two 

 to four rows of somewhat large, spherical or 

 oval nuclei with nucleolL 



/. The outer molecular layer or fenestrated 

 membrane of the same appearance as d. 



fj. The outer nuclear layer. In this the 

 nuclei are spherical or oval, smaller but more 

 numerous than in c. 



h. The outer limiting membrane, seen as a 

 sharp well-defined line. 



i. The layer of rods and cones. Both limbs 

 of the more numerous rods may be easily 

 seen ; the cones are shorter than the rods 

 and are less obvious. 



k. The pigment of the choroid with the fine 

 pencils of processes enveloping the outer 

 limbs of the rods and cones. 



11. Tear off a small piece of the retina from a 

 sheep's eye preserved in Miiller's fluid ; probably 

 the pigment-layer of the retina will be left ad- 

 hering to the choroid. Take a small piece of 

 this pigment-layer, and mount it in glycerine. 

 Observe en face the single layer of hexagonal 

 cells with large pigment-granules (cp. 12, b). 



12. Remove the retina of a frog immediately after 

 death, and place it in osmic acid for 30 minutes 



L. 18 



