ANATOMY OF POSTERIOR ELASTIC LAMINA OF CORNEA. 227 
parts here concerned in the human subject, and how far 
my own observations on the eye of the sheep and ox are at 
variance with it will be seen at a glance. 
** The thickness of Descemet’s membrane” (posterior elastic 
lamina) “amounts to 0:06” to 0°08, and towards the 
borders of the cornea it passes into a peculiar system of 
fibres, which were first observed by Reichert, and described 
more at length by Bowman. ‘This system of fibres com- 
mences at a small distance from the border of the cornea 
at the anterior surface of Descemet’s membrane, and first 
forms an elongated network of fine fibrille, like fine elastic 
fibrils; these then become gradually denser till, at the 
border of the cornea itself, Descemet’s membrane has 
broken up in its entire thickness into a network of thick 
fibres and trabecule, which divides into three portions. 
The one part turns round in the whole circumference of 
the anterior chamber of the eye in the form of numerous 
processes which pass freely through this chamber upon the 
anterior border of the iris; these constitute the lig. iridis 
pectinatum, and coalesce with the anterior part of this 
structure. Another portion passes into the ciliary ligament, 
or rather into the musculus ciliaris ; and the remainder of 
the network prolonged from Descemet’s membrane is lost in 
the inner wall of the canal of Schlemm.” 
From the facts already mentioned it is clear that the 
membrane of Descemet, though much reduced in thickness, is 
traceable beyond the marginal pectinations of the iris into 
the outer wall of the canal of Schiemm. Indeed it may be 
fairly inferred that the delicate lining of the inner wall of 
that canal is an extension of the same coat, after having 
passed in front of the ciliary ligament. This would carry 
the basement of the membrane of the aqueous humour 
farther than is at present admitted ; and to continue a similar 
line of argument, as the conical tubular processes arising 
within the margin of the posterior elastic lamina, visibly 
invest the pectinations of the iris, and a fine plexus of the 
same nature immediately behind them, to a very considerable 
extent, it would not be unreasonable to assume that they 
are in continuity with the delicate but unequivocal tunic of 
the iris itself. 
The membrane of the aqueous humour was formerly 
represented as lining the walls of the anterior and posterior 
chambers of the eye throughout. But a doubt has of late 
been cast upon this view, and the whole extent of the mem- 
brane in question is now supposed to be simply commen- 
surate with the posterior surface of the cornea, upon which 
