THE RETINA. 20 7 



such as may be seen in many pails of the brain ; of numerous 

 cellules, with distinct nuclei, nucleoli, and two, three, or four 

 i-adiating and branching prolongations, as in the cerebrospinal 

 axis ; of numerous blood-vessels ; and of prolongations of the 

 filaments of tlie rods and cones, passing inwards to the inner 

 surface of the retina. It is extremely probable that the 

 nucleated cellules of this layer are connected by ceiiaiu of 

 their prolongations to the filaments of the rods and cones ; the 

 prolongations of the fonuer being continuous with tlie branches 

 of the latter in tlie white cellular layer. It may also be con- 

 fidently stated that, by means of others of their prolongations, 

 the nucleated cellules of this layer are connected with the 

 ultimate filaments of the optic nen-e, wliich form the next 

 layer of the retina. 



The filamentary layer is composed essentially of the 

 ultimate filaments of the optic nerve. These filaments, as 

 soon as they pass off from the spot, enter the retina, lose their 

 medullaiy sheath and dark margins, and assume a delicately 

 transparent gi'ey tint, and somewhat varicose form. They 

 radiate in gradually diminishing anastomosing bundles all 

 round ; but, on the outer side of the optic nerve, they sweep 

 in curves from above, and from below to a line which passes 

 from the centre of the nerve outwards through the yellow 

 spot, converging at the same time somewhat towards that 

 spot. The tenuinations of the constituent filaments of this 

 layer are probably all continuous with certain of the radiations 

 of the nucleated cellules of the grey cellidar layer. The 

 meshes fonned by the bundles of this layer atl'ord passage 

 inwards to the continued prolongations of the filiuuents of the 

 rods and cones. 



The limitary layer completes the retina on the inner side. 

 It is an extremely thin, perfectly transparent membrane, 

 which, although continuous throughout, can only be detached 

 in minute portions, in connection with the terminal attach- 



