30 
Structure of the' 
fMonthly Microscopical 
L Journal, July 1, im 
YII. — Structure of the Adult Human Vitreous Humour* 
By David Smith, M.D., M.E.C.S. 
The almost perfect transparency of the vitreous body has all along 
been the chief impediment which anatomists have felt in investi- 
gating its structure. When it is examined in the fresh state, 
nothing but a few processes and granules can be detected in it 
even with the highest magnifying power, and therefore no hope 
can be entertained of elucidating its structure without the assist- 
ance of reagents. Its minute structure may be demonstrated by 
removing a small fragment from the centre of the humour (thereby 
avoiding any part of its containing envelope), and placing it on a 
glass sHde, to which is then added a drop of concentrated alcohol. 
This has the effect of instantaneously rendering the tissue of the 
humour opaque. Thus treated and subjected to a low magnifying 
power, a network of reticular tissue is observed in the field of the 
microscope, dragged about in all directions from the commotion 
produced by the combination of the alcohol with the fluid of the 
humour. As this motion soon whips the delicate network of tissue 
into irregular ropy fibres, which no amount of maceration can 
again separate, it is necessary, in order to observe the structure 
more minutely, to cover it immediately after the addition of the 
alcohol with a thin pellicle of 
^' glass. Examined with a power 
of three hundred diameters, the 
network of reticular tissue re- 
solves itself into minute tubes 
or canals, intersected by cells at 
variable, but still very minute 
distances apart, thus establishing 
an anastomosis between cell and 
cell, as well as between the re- 
ticulations (Fig. la). The tubes 
are about the size of the elements 
of connective tissue, and the 
cells about ten-thousandth of an 
inch in diameter. 
No matter what part of the 
vitreous humour is examined, the 
same structure is observed ; but 
in and near the circumference of the humour, and particularly near 
the zone of Zinn, another set of fibres is superadded. These consist 
* By the kind permission of Dr. Wakley, we are enabled to reproduce the fol- 
lowing remarks, with illustrations, from the pages of the ' Lancet.' — Ed. M. M. J. 
A a a. Anastomosing cellular tissue of the vitreous 
humour. Bb b, Strong, smooth fibres of the 
cortical portion of the vitreous humour. (Mag- 
nified 300 diameters.) 
