NUNNELEY, ON THE CRYSTALLINE LENS. 147 
12,500, which is, however, by no means certain. He assumes 
that the breadth of all the fibres in each layer is uniform, 
that the breadth of the fibres throughout the whole of the 
layers is five times the thickness, and that the serrations 
uniformly equal the thickness of the fibre, all of which 
assumptions are incorrect, for, while the thickness is tolera- 
bly uniform throughout all the layers, the breadth of the 
fibres not only varies very much in the different layers, but 
the fibres in the same layer vary very considerably im their 
breadth, and the serrations are irregular in number and 
boldness ; some being scarcely perceptible, while others pass 
boldly and deeply, even bifurcating, into the adjoining fibre. 
In the haddock and the cod I found a fibre, taken from 
near the middle layer (equidistant from the margin and axis), 
to measure in breadth 3:5 of an inch, of which the ser- 
rations on each side measured z;355, or the two together 
ss09, Or just equal to the breadth of the solid part of the 
fibre. In this part of the lens I found 2700 fibres to the 
inch linear, while close to the axis there were 5500 to the 
inch; while at the extreme surface the fibres were so indis- 
tinct as hardly to be formed; where they were, they measured 
at least twice, or more, as much as in the middle layers. 
(PL V1, Fie. 3.) 
In the frog, from the middle layer of the lens, I found the 
fibres to be about ;j5, thick and 3,55 wide, but by no 
means uniform in size. The ribbon-shape of these is well 
shown in fig. 4, where two fibres are twisted over upon 
themselves. In the turtle and the alligator there is a 
great difference in the size of the fibres, the outer being very 
broad and flat as compared with those near the axis. (Fig. 5.) 
In the fowl the fibres of the outer layers are very wide, as 
much as 7755 of an inch, as compared with WES from near 
the axis, most of which are not more than ;;155 of an inch, 
but some are considerably broader. The smaller are eylin- 
drical or slightly hexagonal, from pressure against each 
other, while the larger are ribbon-shaped (fie. 65), Ani 
the al the serrations are very sight, and the granules 
composing the fibres are very minute. 
In rodents, as the rat, squirrel, Bere and rabbit, the fas 
measure at the oe of the lens sso, Im the middle 30009 
near the axis sp/95 of an inch; the first bemg deeply serrated, 
the latter very slightly so. 
In a lens taken from a sheep just Sed I found its fibres 
from outer EEGs to be oes z000 tO +345 wide; in the 
ae layer z7s5p Wide, z3'55 thick; at the axis ,75. wide, 
and sz!55 thick. In the ox the Sere vary as we proceed 
