AREOLAR TISSUE. 
131 
form a border composed of the largest vessels of the 
net- work, which are probably veins, joining those of 
the iris. Whilst on this subject, I will point out what 
I consider the true structure of the membrana pupil- 
laris , which, as you are well aware, is generally looked 
upon as a distinct membrane closing the pupillary 
aperture, and when injected, differs from every other 
known membrane in the peculiarity of the arrangement 
of its blood-vessels. In three specimens of injected 
capsules of the lens in the Histological Series, the follow- 
ing peculiarities may be observed. In the first, the entire 
capsule is seen by the naked eye to be covered with 
vessels, those on the poste- 
rior surface represented by b , 
in Fig. 106, being smaller 
than those on the anterior a ; 
but when carefully examined 
with the microscope, the two 
sets will be found to com- 
municate; those on the an- 
terior surface a , are the so 
called vessels of the mem- 
brana pupillaris , and may 
readily be known by their 
forming a series of loops 
near the centre, but leaving 
, that spot without anv vessels. 
Vessels of the capsule of the " 
lens of a Puppy: a. anterior layer It therefore appears that at 
of the capsule ; b, posterior layer. 
one stage of development of 
K 2 
FIG. 106 , 
