ME. J. W. HULKE ON THE CHAMELEON'S RETINA. 225 



a name which I give to a thin band of connective tissue that bounds the outer surface 

 of the inner granule-layer, and which corresponds to the intergranule-layer of other 

 reptiles (fig. 5 i). 



A second set of fibres, corresponding to those which in the Turtle's retina I named 

 the outer radial fibres, crosses the cone-fibre plexus nearly perpendicularly. These 

 vertical radial fibres are most developed where the plexus is thickest (fig. 5). Near 

 the fovea they are very conspicuous, particularly in carmine preparations, in which 

 they are almost colourless, while the bundles of cone-fibres have a deep red tint. In 

 sections parallel to the cone-fibre bundles we see the vertical radial fibres traversing the 

 meshes of the plexus ; while in sections across the bundles, the cut ends of these are 

 packed in long vertical spaces between the radial fibres, which last appear as stout ver- 

 tical pillars that divide at acute angles, and becoming fine and numerous, end at the 

 inner surface of the membrana limitans externa. Near the inner surface of the plexus, 

 tlie stout pillar-like fibres also repeatedly divide, the resulting fibrillse spread in a fan- 

 like manner, and interweaving with others from neighbouring trunks, form the thin 

 band which I call the intergranule-layer. Through this layer the primitive cone-fibres 

 pass to the inner granules. 



The above description of the outer vertical radial fibres and intergranule-layer applies 

 particularly to the central region of the retina; in the periphery, where the retina is 

 thin, a distinct intergranule-layer is not present, and the outer vertical radial fibres are 

 replaced by vertical radial fibres which pass from the inner to the outer limiting 

 membrane. 



4. The Layer of Inner Granules. — This layer throughout the retina is thicker than 

 that of the outer granules. It reaches its greatest development around the fovea cen- 

 tralis, and diminishes towards the periphery in a more gi-adual manner than the outer 

 granule-layer. Several distinct forms of cells and nuclei, and two sets of fibres, a vertical 

 and an oblique, are distinguishable in it. Near the outer surface of the layer, in the 

 central region in close relation to the vertical set of fibres just mentioned, we find small 

 oat-shaped nuclei which carmine scarcely stains. Besides these, other minute nuclei, 

 bright, angular, and also scarcely tinted by carmine, are scattered throughout the layer, 

 apparently in relation with the vertical fibres and interstitial connective tissue. 



Of the cells, some are of a round and roundly oval form, from 9^00" to 45^00 " ^ <iia- 

 meter. Carmine stains them deeply, and many contain a minute nucleus (figs. 6 & 7). 

 In rather thick sections, in which the relations of the elementary parts are less dis- 

 turbed, these cells are often seen disposed in linear series parallel to the oblique fibril- 

 lation to be presently described. Where the layer is broad, they are most numerous 

 in its middle third. There are other cells which are much larger and of an irregular 

 figure (figs. 8, 9, & 10). These have a faint single outline, a pale, finely granulated 

 texture, and contain a large, round, sharply-defined nucleus which nearly fills them, 

 averaging 3^50"- They occur principally near the inner surface of the layer, and 

 are less numerous than the smaller cells. I have frequently seen a broad, flat, pale 



MDCCCLXVI. 2 I 



