NUNNELEY, ON THE CRYSTALLINE LENS. 151 
overcome the aberration of parallax, resides in the lens itself. 
It was this preconceived notion that led Sir E. Home, to 
describe the structureless suspensory ligament of the lens as 
muscular, and determined the celebrated Dr. Young to see 
true muscle in the serrated albuminous fibres of the lens 
itself, and Porterfield to assert the contractile property of 
the ciliary processes ; but that the complicated interlockings 
of millions of serrated fibres, arranged in planes of varying 
curvature and number, should conduce to easy and constant 
modifications in the form of the lens is not a very probable 
supposition. The contrary idea, that they are for the purpose 
of preserving under every circumstance an unchanging sur- 
face would seem the more plausible notion. 
The capsule of lens is a perfectly transparent structure, 
which, though apparently so dense, is very permeable, and, 
like most animal membranes, allows exosmose and endosmose 
very readily to go on. If placed in air the lens soon desic- 
cates ; if put in water the capsule in a short time becomes 
swollen and ultimately bursts from the fluid which passes 
through it; if then punctured, its elasticity forces the water 
in a jet through the aperture. Doubtless it is through its 
pores the lens receives nutriment, as it is non-vascular. In 
structure the capsule differs 7m toto from the lens; none of 
the agents which render the lens opaque affect in the least 
the transparency of the capsule, which it retains for long 
after death. It is highly elastic, and closely embraces the 
lens, whose form, I imagine, it tends most importantly to 
preserve by an equable pressure. It is hard, dense, and 
strong; yet it is readily torn, and is cut with a grating noise. 
Itis so elastic that when divided it at once curls up, and that 
always in a plane opposite to what it is laid down in. If 
injured in the living eye, by even a very small wound, it 
often forces the lens to escape into the aqueous chamber. In 
its physical and chemical characters it appears to be identical 
with the inner elastic layer of the cornea. It is quite struc- 
tureless, and like it has a single layer of epithelial cells upon 
its inner surface. Though when in a normal condition it 
long remains unchanged by either reagents or decomposition, 
very slight injury during life, as the least puncture, at once 
renders it opaque, its elasticity is then lost, and it frequently 
becomes a source of great annoyance to the surgeon by the 
persistency with which it will remain expanded across the 
pupil. 
The inner surface is lined throughout by a single layer of 
cells, similar to those found on the inner aspect of the cornea. 
The cells are very transparent, are nucleated, and polygonal 
