70 BULLETIN OF THE 
pigment layer extends on either side beyond the lens, its outer edge be- 
coming on one side (the lower one in the figure) continuous with the 
inner layer of pigment, and on the other side with the pigment layer of 
the retina. The connection with the outer is shown rather indistinctly 
in the section figured, but much more distinctly in some of the other 
sections of the series, as is also the fact that at places the iris is entirely 
cut off from the retinal pigment. If, then, these layers of pigment have 
come neither from the lens nor the retina, the only other structures 
in this region that they could come from are the vitreous body and the 
hyaloid membrane. In other. respects this eye does not differ appre- 
ciably from the usual structure already described, with this exception, 
that the undifferentiated layer of the retina shows somewhat less differ- 
entiation than usual. I have studied these sections in vain to find 
convincing evidence of actual degeneration within the retinal elements 
themselves, in addition to the pigmentation. 
I now present a table showing some of the results of measurements 
that have been made of the retina, lens, and optic nerve : — 
Two Speci- | Spec. | Spec. Ion, of 
mens,each |50mm. | 60mm, | Cleve- 
19mm, long. | long. | long.! landia. 
4 2 8 4 5 
mm. mm, mm. mm, mm, 
Entire retina nans. Pigment A . +. | 096 | .076 | .110 | ‚146 | .186 
Pigmentlayer . . . „3° « | 056 | 046) -068 | .078 | .042 
Nerve fibre layer. ecs « +... + . + | 0029 .0014¥ .0048| .0058| .05 
Ganglion cell layer .004 | .0029| .0072| .0058) .05 
Inner reticular layer . + a Er °.0198150088 OTIO a 018 c 02 
.0817 
Undifferentiated layer. . . +. + . + + + | 017 5.001 | .0208 
“ Undifferentiated layer” of Nos. 1, 2, and 8: 
Outer nuclear layer . , .0058| .016 
Basal nuclei in outer nuclear layer . .0029' .0029 
Inner nuclear layer (including c outer retic- 
ular layer) . . + " . .0023 
Outer reticular layer EN 0018 
Tangential cell layer . . . « rau +. + + 0029 
Inner nuclear layer . . s . 6 + + 0 0. 029 
Diameter of lens . + . .205 A184 
"Thickness of optic nerve at entrance to retina .011 | 117 
Length of rods . . + + + + + «+ i 082 
Perhaps the most important thing that these measurements reveal is 
the fact that the eyes are subject to great variation, as well in the pro- 
1 The same specimen from which Figures 13 and 21 were drawn. 
